Ataxia Child

Ataxia Child. MRV Head There is no relevant literature to support the use of MRV head in the initial evaluation of a child with recurrent ataxia. Variant 4: Child. Chronic progressive ataxia. Initial imaging. Chronic progressive ataxia is a frequent presentation of ataxia in children. Signs and symptoms are typically of >2 months duration, but occasionally only a few weeks of symptoms may be present [5,14,34]. Cerebellar tumors, brain stem gliomas, and inflammatory disorders are collectively a common cause of chronic progressive ataxia in childhood [1,4,5,25]. Less commonly, inherited ataxias cause chronic progressive ataxias in children [1,4,5,25]. Inherited ataxias are a heterogenous group of clinically and genetically distinguished neurodegenerative disorders, which include autosomal dominant cerebellar ataxias, such as spinocerebellar ataxias, and autosomal recessive cerebellar ataxias, such as Friedreich ataxia. Imaging plays an important role in children with chronic progressive ataxias. Brain imaging is crucial in the assessment of children with suspected brain tumors. In children with inherited chronic progressive ataxias, certain imaging findings can be helpful in the diagnostic workup [1,4,11,28,39-47]. Several hereditary cerebellar ataxias disorders have a progressive clinical course and varying progression of cerebellar hemispheric and vermian volume loss. In addition to cerebellar and vermian atrophy, associated signal abnormality and atrophy of the spinal cord and additional areas of the brain may be seen in certain conditions. Initial imaging provides a baseline for assessment of these abnormalities. Because of the phenotypic heterogeneity and the progressive nature of hereditary cerebellar ataxias, imaging in early childhood may be normal or subtly abnormal with imaging abnormalities becoming more apparent on follow up [14,46,48].


Ataxia Child

Ataxia Child. CT Head Few studies describe the utility of CT in identifying intracranial calcifications in specific conditions such as Cockayne syndrome, which can present with chronic progressive ataxia in children [14,28]. Although CT may identify major structural abnormalities or intracranial mass lesions, MRI is more sensitive for this purpose. CT Complete Spine There is no relevant literature to support the use of CT complete spine in the initial evaluation of a child with chronic progressive ataxia. CTA Head and Neck There is no relevant literature to support the use of CTA head and neck in the initial evaluation of a child with chronic progressive ataxia. CTA Head There is no relevant literature to support the use of CTA head in the initial evaluation of a child with chronic progressive ataxia. CTA Neck There is no relevant literature to support the use of CTA neck in the initial evaluation of a child with chronic progressive ataxia. CTV Head There is no relevant literature to support the use of CTV head in the initial evaluation of a child with chronic progressive ataxia. MRI Head MRI of the head is useful in the clinical workup of children with chronic progressive ataxia and can identify brain tumors and hereditary neurodegenerative disorders [1,4,11,28,39-47]. In a study of 82 patients with spinocerebellar ataxia type 1, 3, or 6, and 32 normal controls, Schulz et al [46] identified significant atrophy of the brainstem, Ataxia-Child cerebellar vermis, and cerebellar hemispheres in affected children. Contrast-enhanced MRI of the head is useful in characterization of brain tumors that are a common cause of chronic progressive ataxia in children [1,4,5,25]. MRI Complete Spine MRI of the spine may be helpful in children with chronic progressive ataxia due to certain causes, such as central nervous system tumors and spinocerebellar ataxias. Postcontrast imaging may be required depending on case specifics, such as in the setting of central nervous system tumors to identify spinal metastatic disease.


Ataxia Child

Ataxia Child. MR Spectroscopy Head There is no relevant literature to support the use of MR spectroscopy head in the initial evaluation of a child with chronic progressive ataxia. Altered metabolite ratios or presence of specific metabolites on MR spectroscopy may be useful in distinguishing posterior fossa tumor types and molecular subtypes. MRA Head and Neck There is no relevant literature to support the use of MRA head and neck in the initial evaluation of a child with chronic progressive ataxia. MRA Head There is no relevant literature to support the use of MRA head in the initial evaluation of a child with chronic progressive ataxia. MRA Neck There is no relevant literature to support the use of MRA neck in the initial evaluation of a child with chronic progressive ataxia. MRV Head and Neck There is no relevant literature to support the use of MRV head and neck in the initial evaluation of a child with chronic progressive ataxia. MRV Head There is no relevant literature to support the use of MRV head in the initial evaluation of a child with chronic progressive ataxia. Variant 5: Child. Chronic nonprogressive ataxia. Initial imaging. Chronic nonprogressive ataxias are comprised of a heterogenous group of cerebellar ataxias with early onset of cerebellar symptoms and no clinical change in severity during follow-up [1,4,25]. Commonly, symptom onset in these cases is within the first year of life, and this group of ataxias are referred to as chronic nonprogressive congenital ataxia [49]. Chronic nonprogressive ataxia in children may be due to syndromic, nonsyndromic, genetic, and acquired etiologies. In some syndromic causes such as Joubert syndrome and related disorders, ataxia is characteristic [50]. There are genetic causes of nonprogressive congenital ataxia with autosomal dominant, autosomal recessive, and x-linked inheritance patterns but with poor correlation between genotype and phenotype defined by imaging and clinical status [49].


Ataxia Child

Ataxia Child. Mutations in the Reelin signaling pathway are one of the autosomal recessive nonprogressive congenital ataxias with marked cerebellar and vermian hypoplasia and gyral simplification [4]. Developmental causes of nonprogressive congenital ataxia include posterior fossa malformations, such as rhombencephalosynapsis, Dandy-Walker syndrome, and Chiari II malformations [4]. Acquired causes of nonprogressive congenital ataxia include prenatally acquired cerebellar injury such as congenital cytomegalovirus infection, in utero cerebellar stroke, and perinatal disrupted development of the cerebellum as can be seen in premature infants and those with perinatal ischemic injury [51]. In the setting of chronic nonprogressive ataxia, imaging can be helpful in identifying the presence of congenital cerebellar, vermian, brainstem, and supratentorial brain malformations and acquired cerebellar disruptions due to prenatal or perinatal insult, although imaging can be normal in genetic etiologies [1,4,25,40]. CT Head Although CT may provide an assessment of major structural abnormalities in the posterior fossa, CT is less sensitive than MRI for assessment of intracranial structures [14,28]. The use of IV contrast is generally not warranted in assessment of brain structural abnormalities that present with chronic nonprogressive ataxia in children. Ataxia-Child CT Complete Spine There is no relevant literature to support the use of CT complete spine in the initial evaluation of a child with chronic nonprogressive ataxia. CTA Head and Neck There is no relevant literature to support the use of CTA head and neck in the initial evaluation of a child with chronic nonprogressive ataxia. CTA Head There is no relevant literature to support the use of CTA head in the initial evaluation of a child with chronic nonprogressive ataxia. CTA Neck There is no relevant literature to support the use of CTA neck in the initial evaluation of a child with chronic nonprogressive ataxia.


Ataxia Child

Ataxia Child. CTV Head There is no relevant literature to support the use of CTV head in the initial evaluation of a child with chronic nonprogressive ataxia. MRI Head MRI is the most widely utilized imaging method to evaluate chronic nonprogressive ataxia [4,32]. In a child with chronic nonprogressive ataxia, MRI is useful in identifying cerebellar and brainstem malformations to aid diagnosis. Imaging can be particularly useful in the diagnosis of certain syndromic causes of chronic nonprogressive ataxia such as rhombencephalosynapsis, Dandy-Walker or Joubert syndrome, and related disorders that have characteristic imaging findings [50]. Diffusion tensor imaging can facilitate assessment of white matter tract structure in congenital brainstem and cerebellar anomalies [4,6,43,52]. For example, absence of decussation of the superior cerebellar peduncles in Joubert syndrome and abnormal dorsal pontine transverse white matter bundles in pontine tegmental cap dysplasia are seen on diffusion tensor imaging [4]. There is no literature to support the use of IV contrast in this setting. MRI Complete Spine Because some congenital brainstem and cerebellar anomalies that present with chronic nonprogressive ataxia are associated with spinal anomalies, MRI of the complete spine may be helpful in individual cases [44]. There is no literature to support the use of contrast-enhanced imaging of the spine in this scenario. MR Spectroscopy Head There is no relevant literature to support the use of MR spectroscopy head in the initial evaluation of a child with chronic nonprogressive ataxia. MRA Head and Neck There is no relevant literature to support the use of MRA head and neck in the initial evaluation of a child with chronic nonprogressive ataxia. MRA Head There is no relevant literature to support the use of MRA head in the initial evaluation of a child with chronic nonprogressive ataxia.


Postmenopausal Subacute or Chronic Pelvic Pain.  Subacute or chronic pelvic pain is a broad clinical presentation common to a variety of gynecologic, urinary, gastrointestinal, and musculoskeletal disorders. There are specific ACR Appropriateness Criteria documents pertaining to many of these diagnoses, which are detailed in Appendix 1. In particular, we emphasize the importance of both vaginal bleeding and suspected adnexal mass in postmenopausal women because of the prevalence of endometrial and ovarian neoplasia in this age group. These clinical features, if present, should take precedence over the general complaint of pelvic pain in directing the management algorithm. Patients with acute pain, suspected pelvic floor dysfunction, or urinary complaints may be managed in accordance with the respective algorithms for those conditions. Imaging evaluation for suspected endometriosis is not considered here as endometriosis is estrogen dependent and usually regresses after menopause [3]. If a postmenopausal woman is experiencing pain from endometriosis, it is likely secondary to scarring or reactivation that is due to postmenopausal hormonal therapy. In cases of persistent endometriosis-related symptoms after menopause, readers are referred to ACR Appropriateness Criteria guidance for the premenopausal age group (see Appendix 1). Finally, like other types of chronic pain, pelvic pain is a complex process with incompletely mapped cognitive and neurologic contributors. As such, there is a growing body of literature regarding potential use of neurologic imaging in patients with chronic pelvic pain [4-7]. However, central nervous system functional imaging remains in the research domain for evaluation of chronic pelvic pain at this time, so we will not consider it formally among the discussed imaging procedures. When all of these aspects of subacute and chronic pelvic pain in postmenopausal women are excluded from direct consideration, a handful of clinically significant conditions remain.


Postmenopausal Subacute or Chronic Pelvic Pain. We group these according to location of clinical symptoms: pain localized to the deep or internal pelvis, with potential etiologies and associated conditions, including pelvic venous disorders (commonly termed pelvic congestion syndrome), intraperitoneal adhesions, hydrosalpinx, chronic inflammatory disease, or cervical stenosis versus chronic pain localized to the perineum, vulva, or vagina that arises from suspected vaginal atrophy, vaginismus, vaginal or vulvar cysts, vulvodynia, or pelvic myofascial pain. Special Imaging Considerations When there is suspected local pathology in the vulva, perineum, or vaginal wall, translabial/transperineal ultrasound (US) or side-firing transvaginal probes may provide better visualization than end-firing transvaginal The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Postmenopausal Subacute or Chronic Pelvic Pain US probes [8]. There is scant evidence for imaging recommendations at this level of specificity, and it is assumed that the performing sonographer and sonologist will make appropriate technical adjustments to optimize imaging in these relatively uncommon clinical scenarios. Discussion of Procedures by Variant Variant 1: Postmenopausal subacute or chronic pelvic pain, localized to the deep pelvis. Initial imaging. Radiography Abdomen and Pelvis To our knowledge, there is currently no evidence to support the use of radiography to evaluate postmenopausal subacute or chronic pelvic pain localized to the deep pelvis.


Postmenopausal Subacute or Chronic Pelvic Pain. US Pelvis Transvaginal Pelvic US using a combined transabdominal and transvaginal approach is the initial imaging study of choice to evaluate postmenopausal subacute or chronic pelvic pain localized to the deep pelvis [9-12]. US can provide anatomic information about uterine size and endometrial canal distension, fallopian tube dilation, ovaries, and adnexal masses. Regarding the sequencing of examinations, several authors have pointed out that if the etiology of pelvic pain remains obscure after CT, a subsequent US has the capacity to provide additional information about the adnexa in particular [13,14]. US is broadly used and clinically accepted worldwide. However, high-quality evidence, such as clinical trials supporting specific usefulness of US, is lacking. Chronic pelvic inflammatory disease may be associated with pelvic fluid, hydrosalpinx or pyosalpinx, inflammatory adnexal masses, and peritoneal inclusions visible by US [15]. When pelvic adhesions are suspected, real-time dynamic US or cine clips may document abnormal adherence or lack of mobility of structures, particularly transvaginally. However, adhesive disease is a notoriously difficult diagnosis to confirm nonoperatively [16], and the evidence basis is anecdotal [15,17]. Furthermore, the causal linkage between adhesive disease and chronic pelvic pain remains unclear. Many women with pelvic venous disorders have morphologic findings of polycystic ovarian syndrome (enlarged ovaries with exaggerated central stroma and multiple small peripherally located follicles), but the associated clinical features of hirsutism and amenorrhea are rare [11,18]. Multiple investigators have identified a component of estrogen overstimulation in pelvic venous disorders, and symptoms may subside after menopause in some women [15]. There is a lack of clear definition and high-quality evidence in the clinical domain of pelvic venous disorders.


Postmenopausal Subacute or Chronic Pelvic Pain. CT Abdomen and Pelvis When pelvic venous disorders are clinically suspected, contrast-enhanced CT of the abdomen and pelvis may demonstrate engorged periuterine and periovarian veins, venous anatomic variants, and occasional compression of the left renal vein resulting in asymmetric left-sided pelvic varicosities [10,19-22]. However, CT lacks the capacity of US or MR to provide dynamic flow information [18]. CT Pelvis When pelvic venous disorders are clinically suspected, contrast-enhanced CT of the pelvis may demonstrate engorged periuterine and periovarian veins, although their drainage into the renal vein or cava will not be evaluated without CT coverage of the abdomen [10,19-22]. In chronic inflammatory disease, CT may demonstrate pelvic fluid, peritoneal thickening, hydrosalpinx or pyosalpinx, and tubo-ovarian abscess [23]. MRI Pelvis MRI is widely regarded as the problem-solving imaging examination of choice for chronic pelvic pain, particularly when US findings are nondiagnostic or inconclusive [11,15,24]. When MRI is clinically indicated, the use of a gadolinium-based IV contrast agent is preferred. Please see the ACR Manual on Contrast Media for additional information [25]. The diagnostic performance of MRI/MR angiography is comparable to conventional venography for identifying pelvic venous disorders [26,27]. The use of MRI for this indication is growing accordingly [28], necessitating standardized interpretation and reporting [29]. T2-weighted imaging has the capacity to demonstrate pelvic varices, but signal intensity varies with flow velocity. Vein conspicuity and flow directional assessment are superior using time-resolved postcontrast T1-weighted imaging, which can directly demonstrate ovarian vein reflux [10,30]. Noninvasive imaging with MRI has largely supplanted conventional venography for diagnostic purposes, but venography may still be performed in the context of intended intervention.


Postmenopausal Subacute or Chronic Pelvic Pain. In chronic pelvic inflammatory disease, MRI with T2-weighted imaging may demonstrate edema, fluid collections, and distension of endometrial canal or fallopian tubes [15]. When infection is long standing, distinguishing between inflammatory and neoplastic masses is particularly difficult. Postcontrast T1-weighted imaging and diffusion-weighted imaging are particularly important in this setting [23]. Adhesive disease may be directly evident at MRI as low-signal bands between structures on nonfat saturated T2-weighted imaging or inferred in the presence of peritoneal inclusion cysts [11,15]. Variant 2: Postmenopausal subacute or chronic pelvic pain, clinically suspected pathologies in perineum, vulva, or vagina. Initial imaging. Physical examination is the foundation of clinical evaluation of suspected pathology in the perineum, vulva, or vagina. The evidence supporting the use of imaging procedures in this clinical context largely assumes that the physical examination is abnormal. Radiography Abdomen and Pelvis To our knowledge, there is currently no evidence to support the use of radiography to evaluate postmenopausal subacute or chronic pelvic pain localized to the perineum, vulva, or vagina. US Pelvis Transvaginal Physical examination is the basis of diagnosis for most conditions localized to the vulvar skin [31]. Perineal and vaginal cysts are subcutaneous but often palpable and are appropriately evaluated with either translabial or transvaginal US, or both [8]. As with pelvic pain localized to the deep pelvis, US is widely regarded as the initial imaging study of choice for pelvic pain localized to the perineum, vulva, or vagina, but there is little high-quality evidence specifically supporting its use. Postmenopausal Subacute or Chronic Pelvic Pain US Duplex Doppler Pelvis Color and spectral Doppler are routinely used in pelvic sonography to evaluate internal vascularity of pelvic observations and distinguish cysts from soft tissue.


Postmenopausal Subacute or Chronic Pelvic Pain. Although it is rated as a separate imaging procedure per ACR methodology, the expert panel considers Doppler imaging to be a standard component of pelvic sonography. Special considerations for women with chronic pelvic pain may include evaluation of uterine artery blood flow, with low-resistance waveforms having been described in women with chronic pelvic pain [12]. CT Abdomen and Pelvis To our knowledge, there is currently no evidence to support the use of CT for primary evaluation of postmenopausal subacute or chronic pelvic pain localized to the perineum, vulva, or vagina. CT Pelvis To our knowledge, there is currently no evidence to support the use of CT for primary evaluation of postmenopausal subacute or chronic pelvic pain localized to the perineum, vulva, or vagina. MRI Pelvis When MRI is clinically indicated, the use of a gadolinium-based IV contrast agent is preferred. Please see the ACR Manual on Contrast Media for additional information [25]. When a cyst or mass is identified by US in the perineum, vulva, or vagina, MRI provides additional anatomic detail and evaluation of any enhancing soft-tissue components that might favor infection or neoplasia [11,24,32,33]. MRI has an important role as a problem-solving examination for lesion characterization and surgical planning, but there is, to our knowledge, no direct evidence to support the use of MRI as the initial or primary imaging examination for evaluation of pelvic pain localized to the perineum, vulva, or vagina, particularly when the physical examination is normal. However, there is emerging evidence to support the first- line utility of MRI when endometriosis or fistulizing disease are suspected [34]; readers are again referred to specific ACR Appropriateness Criteria guidelines for these clinical scenarios (see Appendix 1). MRI also enables accurate depiction of pelvic floor muscular anatomy, integrity, and function [35,36].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease.  Introduction/Background Nontraumatic aortic disease can be caused by a wide variety of disorders, including congenital, inflammatory, infectious, metabolic, neoplastic, and degenerative diseases. Such conditions include, but are not limited to, atherosclerosis, aortic dissection, intramural hematoma, penetrating aortic ulcer, aortic aneurysms of various etiologies (degenerative, mycotic, or vasculitis-related), aortic rupture, thrombosis, aortobronchial fistula, congenital disorders, and extrinsic compression from adjacent masses. Diagnostic imaging is essential to assess the anatomy and extent of morphological changes involving the aorta. Nontraumatic aortic diseases may affect the lumen, wall, or perivascular structures. When there is aortic branch vessel involvement, end organ perfusion may be compromised. Often, aortic disorders involve both the thoracic and abdominal aortic segments, thus requiring imaging of both regions. The clinical symptoms of aortic diseases vary widely. For example, acute aortic syndrome presents acutely with chest pain and elevated blood pressure, whereas atherosclerosis may be asymptomatic and detected incidentally. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. aUniversity of Alabama at Birmingham, Birmingham, Alabama. bPanel Chair, Massachusetts General Hospital, Boston, Massachusetts. cPanel Vice-Chair, Emory Healthcare, Atlanta, Georgia. dSt. Francis Hospital, Catholic Health Services of Long Island, Roslyn, New York; Society for Cardiovascular Magnetic Resonance. eTufts University School of Medicine, Boston, Massachusetts; Society for Vascular Surgery.


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. fKnight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon; Society of Cardiovascular Computed Tomography. gMassachusetts General Hospital, Boston, Massachusetts. hMayo Clinic, Rochester, Minnesota. iUniversity of Virginia, Charlottesville, Virginia. jLoyola University Medical Center, Maywood, Illinois. kThe Warren Alpert School of Medicine at Brown University, Providence, Rhode Island; Nuclear cardiology expert. lMassachusetts General Hospital, Boston, Massachusetts. mUT Southwestern Medical Center, Dallas, Texas. nStanford University Medical Center, Stanford, California. oSpecialty Chair, Emory University Hospital, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org OR Discussion of Procedures by Variant Variant 1: Congenital aortic disease. Initial imaging. Aortography Chest and Abdomen Catheter-based aortography is considered the reference standard for the diagnosis of congenital aortic diseases [10]. Aortography provides information regarding flow and allows hemodynamic measurements to be taken; however, several noninvasive studies can provide similar information. As such, the role of aortography in diagnosing aortic diseases is decreasing as the sensitivity of other noninvasive modalities, such as transthoracic echocardiography (TTE), CTA, and MR angiography (MRA) improves [11-18]. Aortography is now most commonly performed when an intervention is planned. CT Chest and Abdomen There is no relevant literature available to examine the use of CT chest and abdomen with intravenous (IV) contrast alone in the management of congenital aortic disease.


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. There is no relevant literature available to examine the use of CT chest and abdomen without and with IV contrast in the management of congenital aortic disease. CTA Chest and Abdomen with IV Contrast As a modality, CTA provides excellent spatial resolution, fast acquisition times, and the ability for 3-D reconstruction [6,16]. Another advantage of CTA is the ability to visualize cardiac structures and coronary arteries, as several congenital aortic processes are associated with cardiac abnormalities [19]. One study found that a prospectively triggered, dual-energy, high-pitch protocol CTA was more accurate than echocardiography in the diagnosis of coarctation [20]. Another series found CTA to be 100% accurate compared with operative findings in evaluating the diameter and length of aortic coarctation [18], whereas others have demonstrated CTA to compare favorably to both operative and catheter-based angiographic findings [11-14]. These findings make CTA a valuable, noninvasive imaging study for aortic characterization that can help to guide future interventions [19]. However, CTA does not provide direct hemodynamic information [10]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature for the use of PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)- PET/CT imaging in the evaluation of congenital aortic disease. MRA Chest and Abdomen The relevant literature focuses on cardiac MRI, rather than MRA of the chest and abdomen, for evaluating congenital aortic disease. Cardiac MRI is becoming standard practice in evaluating patients with suspected congenital aortic pathology [21]. Even though it has lower spatial resolution than CT, MRA provides important physiologic information, including pressure gradients, extent of collateral flow, contractility of the myocardium, and evaluation of the valves [22].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. Physiologic measurements are especially critical in evaluating coarctation where the smallest cross-sectional diameter of the aorta and flow deceleration in the descending aorta measured on velocity-encoded cine MRI are excellent predictors of a hemodynamically significant stenosis [15,17]. Newer 4-D sequences may improve the evaluation of vascular flow and hemodynamics, such as shear stress, pressure gradients, and turbulence [23-25]. Because of cardiac motion, 3-D noncontrast navigator MRA, steady-state 3-D contrast- enhanced MRA, or gated first-pass contrast-enhanced MRA is preferable to evaluate the aortic root [26,27]. Nontraumatic Aortic Disease The addition of IV contrast for MRA can be beneficial in evaluating congenital aortic diseases. For example, contrast-enhanced MRA has a higher sensitivity, specificity, and accuracy for detecting obstructive aortic anomalies when compared with either TTE or MRA without IV contrast [28]. Contrast-enhanced MRA may also improve visualization of the aorta when compared with fast spin-echo sequences [29]. US Echocardiography Transthoracic TTE is a useful modality during the evaluation of congenital aortic abnormalities, given its association with cardiac abnormalities. For example, the reported incidence of bicuspid aortic valve in the setting of aortic coarctation ranges from 30% to 40% [19]. TTE is often the initial imaging modality when coarctation of the aorta is suspected [16], even though its utility can be reduced in the adult population because of its limited acoustic windows [21]. These limitations can be overcome somewhat through the use of the suprasternal view and Doppler imaging [20]. In addition to anatomic information, TTE can provide valuable physiologic parameters. For instance, Doppler can estimate peak velocities and pressure gradients across a stenosis [39,40]. TTE can also provide information regarding cardiac contractility, direction of flow, and valvular disorders [41].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. Despite these advantages, TTE is limited in its ability to evaluate the aortic arch and proximal descending aorta [42,43]. US Echocardiography Transesophageal Transesophageal echocardiography (TEE) can provide views of the descending aorta, but physiologic information derived from these views can be inaccurate [21]. TEE is invasive and may not provide additional information than that gained from TTE [10]. Variant 2: Inflammatory or infectious or neoplastic or metabolic nontraumatic aortic disease. Initial imaging. Aortography Chest and Abdomen Catheter-based aortography provides high spatial and temporal resolution, but because of its invasive nature and inability to detect changes to the vessel wall, it is considered inferior to cross-sectional imaging modalities. For example, a recent meta-analysis found that CT, MRI, and US were better than catheter-based angiography in detecting vascular lesions resulting from Takayasu arteritis [44]. Aortography is of most benefit when an intervention is planned. Overall, the addition of a contrast-enhanced CT scan after an unenhanced CT scan may be of benefit. For suspected vascular infection, one small series found rim enhancement to be the only finding associated with infection that required the administration of IV contrast [45]. Other findings in this series associated with infection did not need Nontraumatic Aortic Disease For suspected vascular infection, CT imaging without IV contrast has some value in identifying signs associated with infection, including perivascular stranding, gas, wall thickening, aneurysmal dilatation, and involvement of adjacent bony structures [45,48]. Similarly, periaortic hemorrhage from ruptured aneurysm can be identified on CT without IV contrast [49]. Benign and malignant aortic tumors are exceedingly rare and often difficult to prospectively diagnose on imaging [50]. For suspected primary vascular neoplasms, an irregular soft-tissue density adjacent to the vessel wall may be seen [46,47].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. CT imaging without IV contrast has little value in the diagnosis of inflammatory or metabolic aortic diseases. MRA Chest and Abdomen Contrast-enhanced MRA techniques have evolved with the introduction of k-space and image-based acceleration techniques, higher field strengths, ultra-fast gradients, and the use of 3-D gradient-echo techniques. Double or triple inversion recovery and balanced steady-state free-precession pulse sequences are acquired before applying contrast- enhanced MRA. Additionally, delayed high-resolution T1-weighted images are acquired to assess aortic wall enhancement, especially in the cases of suspected inflammatory or infectious processes. Contrast-enhanced MRI can be particularly useful in the evaluation of inflammatory conditions as it can detect wall enhancement, which is a sign of active Takayasu arteritis [66]. Moreover, a recent meta-analysis reported that the addition of contrast- enhanced sequences improved the sensitivity of MRA in detecting Takayasu arteritis from 79% to 92% [44]. The same study showed that contrast-enhanced MRA outperformed catheter-based angiography. Similarly, contrast- enhanced MRI allows for improved detection of wall enhancement in both GCA [67-70] and Behcet disease [55,71]. For suspected neoplasms, contrast-enhanced MRI may be able to help differentiate between atheromatous plaque and tumor as well as help to delineate extravascular extension [72]. Regarding infection, the utility of contrast- enhanced MRA is similar to that of CTA in its ability to detect aneurysms, edema, perivascular stranding, gas, and disrupted calcifications [50]. MRA without IV contrast has some utility in the diagnosis of inflammatory vascular conditions. For example, one meta-analysis found MRA to be 79% sensitive and 97% specific in the diagnosis of Takayasu arteritis, outperforming catheter-based angiography [44]. MRA without IV contrast is able to identify extracranial Nontraumatic Aortic Disease involvement in GCA [73].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. As discussed above, this modality is unable to provide an assessment of wall enhancement, which is an important marker in many inflammatory conditions. Similar to unenhanced CT, MRA without IV contrast is able to identify aneurysms, edema, perivascular stranding, gas, and disrupted calcifications that may be associated with aortic infections [50]. For suspected neoplasms, an irregular soft-tissue structure may be identified that may or may not enhance after IV contrast administration [46,47]. Radiography Chest Chest radiography may be helpful in evaluating the contour, size, and location of the thoracic aorta and the great vessels, which, if abnormal, would prompt further investigation [10,21]. Radiography is not considered an adequate modality to evaluate for inflammatory, infectious, neoplastic, or metabolic aortic diseases. Vascular duplex US can identify vascular wall thickening, which is an important marker in patients with generalized vascular inflammation [74], GCA [73,75], Behcet disease [76], and Takayasu arteritis [44]. Additionally, US is better than catheter-based angiography for detecting stenoses, occlusions, and aneurysms from Takayasu arteritis [44]. Nonetheless, it must be remembered that these evaluations primarily focused on nonaortic vessels. In fact, one study compared duplex US to FDG-PET/CT for the detection of extracranial large vessel vasculitis and found that US was only 26% sensitive for detecting aortic involvement. Other authors have also recognized the limitations of US for measuring wall thickness of the aorta [44,75]. For suspected neoplastic processes, US is of little value because it is not able to reliably differentiate between malignant and benign tissue [50]. There is no relevant literature available to examine the use of US in suspected aortic infection.


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. US Echocardiography Transthoracic TTE can view the thoracic aorta (mainly the ascending aorta and, to some extent, the proximal descending aorta and arch) and the aortic valve (for presence and quantification of aortic regurgitation). There is no relevant literature supporting TTE as the initial imaging modality when evaluating infectious, inflammatory, metabolic, or neoplastic processes in the aorta. US Echocardiography Transesophageal TEE may provide views of the descending aorta not appreciated on TTE, but there is no relevant literature supporting TEE as the initial imaging modality when evaluating infectious, inflammatory, metabolic, or neoplastic processes in the aorta. Aortography Chest and Abdomen Aortography no longer has a significant role as the initial imaging modality for suspected degenerative or atherosclerotic disease of the aorta, as the availability and accuracy of noninvasive methods continues to increase. Catheter-based angiography remains a critical component of care when an intervention is planned. Nontraumatic Aortic Disease CTA Chest and Abdomen with IV Contrast CTA with IV contrast is an important tool when evaluating the aorta for suspected degenerative and atherosclerotic changes as it provides information about the aortic lumen, the aortic wall, and surrounding aortic structures [86,87]. CT can also be used to detect other pathologies in the lungs, chest wall, and pleura, which can mimic the symptoms of aortic disease [88]. The addition of a venous phase to the CTA appears to increase its ability to identify both benign and malignant incidental pathology in nonvascular structures. [89]. Electrocardiograph (ECG)-gated aortic CTA decreases pulsation artifacts of the ascending aorta, which allows for a more accurate measurement of the ascending aortic diameter and potentially increases diagnostic confidence [90]. CTA provides information about the aortic root [91], aortic valve area and function, aortic wall elasticity, and morphology in general [92,93].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. The CTA 3-D data set can be postprocessed and manipulated perpendicular to the flow lumen, allowing for accurate measurements for longitudinal evaluation of aortic growth and lumen diameters as well as planning for endovascular or surgical treatment [87,94,95]. Even though the maximum diameter of the aorta is the most consistent predictor of future rupture, other CTA findings, such as luminal contrast heterogeneity, intraluminal thrombus volume, aortic wall distensibility, and aneurysm geometry, help identify patients at risk for rupture [96-98]. Geometric models from CTA examinations can be used to create computational flow dynamics, which may also be useful in identifying patients with thoracic aortic aneurysms who are at risk for rupture [99]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature for the use of FDG-PET/CT imaging as an initial evaluation of degenerative or atherosclerotic aortic diseases. MRA Chest and Abdomen Similar to MRA without IV contrast, MRA without and with IV contrast can be used to obtain hemodynamic information about aortic aneurysms from computational flow dynamics or 4-D flow MRI [99]. The addition of IV contrast improves visualization of the aorta and great vessels and decreases overall acquisition time [100-104]. However, there is no definitive evidence that the addition of IV contrast improves the overall accuracy of MRA for degenerative aortic diseases. MRI without IV contrast using double-inversion recovery T1-weighted imaging and balanced steady-state free- precession MRA allows for imaging of the aorta, especially when acquisition is ECG-gated [105]. The accuracy of balanced steady-state free-precession MRA is close to 100% for detecting thoracic aortic aneurysm, dissection, intramural hematoma, and penetrating aortic ulcer when measured against the reference standard of MRA with IV contrast material [101,106]. It can be used to evaluate the entire thoracic aorta and its branches [107].


Nontraumatic Aortic Disease

Nontraumatic Aortic Disease. MRA without IV contrast can also be used to create geometric models for computational flow dynamics [99]. Additionally, 4-D flow MRI sequences can be obtained [99]. These sequences are the acquisition of 3-D phase-contrast images in a time-resolved, ECG-gated manner with 3-D velocity encoding. Both computational flow dynamics and 4-D flow MRI can be used to examine hemodynamic information in thoracic aortic aneurysms, such as wall shear stress, flow patterns, and helical flow that may help to identify patients at risk for rupture [99]. For aortic atherosclerotic disease, both MRA without IV contrast and MRA without and with IV contrast can be used to collect physiologic information about aortic flow in order to provide an assessment of aortic wall stiffness and to generate 4-D flow MRI [42,99]. One disadvantage of MRI of the chest and abdomen without and with IV is that it may underestimate the thickness of atherosclerotic plaques compared with other modalities [108]. One advantage of MRI of the chest and abdomen is that it can be used to evaluate the composition of atherosclerotic plaques for lipids, fibrosis, calcifications, and intraplaque hemorrhage [95,109]. Because of improved visualization and decreased acquisition times, the use of IV contrast for MRA of the chest and abdomen is preferred, but sufficient information can also be obtained without the use of IV contrast [100-104,110]. Radiography Chest The chest radiograph is a helpful initial imaging evaluation for the diagnosis of degenerative aortic disease, especially if an acute complication is suspected. However, because of the lack of sensitivity in assessing the extent of disease [35], more definitive tests are required. Regarding atherosclerotic aortic disease, some studies have used lateral lumbar radiographs to both quantify and correlate atherosclerotic disease in the aorta to bone mineral density Nontraumatic Aortic Disease [111], patient diet [112], and more generalized atherosclerotic disease [113].


Acute Pancreatitis

Acute Pancreatitis.  Introduction/Background Acute pancreatitis (AP), an inflammatory process affecting the pancreas, is the third most frequent gastrointestinal cause of hospital admissions in the United States [1]. AP results in approximately 300,000 hospital admissions each year, with associated costs of approximately $2.6 billion [1,2]. The incidence of AP is increasing and is estimated at 40 per 100,000 people. The clinical diagnosis of AP requires 2 of the following 3 features: 1) abdominal pain consistent with AP (acute onset of persistent, severe, epigastric pain often radiating to the back); 2) serum lipase or amylase levels at least 3 times the upper limits of normal; and 3) characteristic findings of AP on contrast-enhanced CT, MRI, or transabdominal ultrasound (US) [3]. As such, if the abdominal pain is characteristic of pancreatitis and the amylase or lipase levels are not elevated to at least 3 times above normal, imaging is required for diagnosis. Imaging is also performed in AP to investigate the etiology, complications, and extent of disease. Imaging AP requires an understanding of the disease subtypes, evolution, and associated complications. Familiarity with the appropriate radiologic nomenclature as defined by the Atlanta symposium in 1992 and, more recently, modified by the Acute Pancreatitis Classification Working Group in 2008 is also essential [3]. Special Imaging Considerations Radiographs Conventional radiographs and upper gastrointestinal series currently have a limited role in the evaluation of a patient with AP. Radiographic signs of AP, such as dilated air-filled duodenum or jejunum, are secondary and nonspecific. Similarly, thickened rugal or duodenal folds or dilation of the duodenal C-loop are nonspecific findings of AP seen on upper gastrointestinal series or follow-through studies.


Acute Pancreatitis

Acute Pancreatitis. Occasionally, radiographs may be useful when obtained for evaluation of nonspecific abdominal pain, as one can quickly assess for the presence of bowel obstruction or calcified gallstones in the gallbladder or common bile duct. Radiographs can also be useful for evaluating the presence of biliary or pancreatic duct stents. aUniversity of Alabama Medical Center, Birmingham, Alabama. bJohns Hopkins Hospital, Baltimore, Maryland. cPanel Chair, Johns Hopkins University School of Medicine, Baltimore, Maryland. dPanel Vice-Chair, Northwestern University, Chicago, Illinois. eUniversity of Arizona, Banner University Medical Center, Tucson, Arizona. fGlobal Advanced Imaging, PLLC, Little Rock, Arkansas. gDuke University Medical Center, Durham, North Carolina. hThe University of South Florida Morsani College of Medicine, Tampa, Florida. iUniversity of Texas Health Science Center at Houston and McGovern Medical School, Houston, Texas; American Gastroenterological Association. jMontefiore Medical Center, Bronx, New York. kUMass Memorial Medical Center, Worcester, Massachusetts. lUniversity of Florida College of Medicine, Gainesville, Florida. mRush University Medical Center, Chicago, Illinois; American College of Surgeons. nNew York University Medical Center, New York, New York. oStanford University Medical Center, Stanford, California. pUniversity of Alabama Medical Center, Birmingham, Alabama. qSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org


Acute Pancreatitis

Acute Pancreatitis. Acute Pancreatitis for evaluation of gallstones and it is nondiagnostic, possibly because of obesity, gas, etc, and an MRI could not be performed. Patients with acute biliary pancreatitis may undergo early ERCP for removal of stones causing common bile duct obstruction to reduce disease severity and risk of complications [9,10]. The appropriate timing of ERCP is controversial [9,11]. Some authors argue that if ERCP has to be performed in patients with gallstone-related AP, it should be performed within 72 hours to have the highest chance of mitigating the pancreatic inflammatory process and reducing systemic complications [10]. However, the majority of patients with gallstone pancreatitis suffer from transient obstruction with spontaneous resolution [9]. Approximately half of the patients with cholestatic liver biochemistry and a dilated common bile duct on US or CT did not have a common bile duct stone detected during ERCP [10]. Because ERCP is an invasive procedure that can sometimes lead to complications, including perforation and hemorrhage, accurately identifying those patients with choledocholithiasis who are most likely to benefit from early therapeutic ERCP is important. MRCP images of the biliary system are more sensitive and specific than US for the detection of choledocholithiasis [9,12]. MRCP has a high concordance rate with ERCP for the detection of biliary origin of AP [9]. As such, MRCP prior to ERCP in patients at high risk for choledocholithiasis is common, replacing diagnostic ERCP in many cases. There is conflicting evidence regarding whether the selective use of MRCP in patients at high risk for choledocholithiasis reduces hospital stay and resultant hospital charges [9,13]. MRCP has the added advantage of detecting anatomic anomalies that may contribute to the etiology of AP, such as pancreas divisum or bile duct or pancreatic duct strictures. Therefore, for the assessment of biliary pathology on MRCP, MRI without IV contrast with MRCP may serve as a problem-solving tool.


Acute Pancreatitis

Acute Pancreatitis. US Abdomen with IV Contrast Contrast-enhanced US (CEUS) is emerging as a potential option for focal evaluation of the pancreas, and it is well suited to the evaluation of perfusion with its use of intravascular contrast agents [15]. However, the use of microbubble contrast for this indication is currently not approved by the FDA, and its use would be considered off-label. Additionally, in a majority of patients, the diagnosis of AP can be made based on the clinical findings of typical abdominal pain and elevated serum lipase or amylase levels to at least 3 times the upper limits of normal or greater. Therefore, CEUS may not provide additional information in patients with an unequivocal clinical presentation and appropriately elevated amylase and lipase. Similar to grayscale US, CEUS is limited by bowel gas, which can be particularly problematic in patients with AP and frequently associated paralytic ileus. US Duplex Doppler Abdomen Adding spectral, color, and power Doppler US to traditional grayscale US adds hemodynamic information concerning vessel patency and flow direction and may be useful for differentiating vascular from nonvascular Acute Pancreatitis structures, particularly differentiating hepatic arteries and portal veins from bile ducts. Every patient presenting with AP and no obvious alternative etiology should undergo transabdominal US to assess for gallstones as the possible cause [12]. Spectral, color, and power Doppler should be used as necessary to differentiate vascular from nonvascular structures in this instance. However, beyond evaluating for gallstones in the large majority of patients, the diagnosis can be made based on typical clinical symptoms and laboratory findings of an amylase and/or lipase level elevated to 3 times the upper limit of normal, or greater, without additional cross-sectional imaging [1]. Variant 2: Suspected acute pancreatitis.


Acute Pancreatitis

Acute Pancreatitis. Initial presentation with atypical signs and symptoms; including equivocal amylase and lipase values (possibly confounded by acute kidney injury or chronic kidney disease) and when diagnoses other than pancreatitis may be possible (bowel perforation, bowel ischemia, etc). Initial imaging. CT Abdomen and Pelvis In patients with acute abdominal pain, there are often multiple potential etiologies to consider, including peptic ulcer disease, bowel perforation, and mesenteric ischemia, among others. Laboratory studies, specifically serum amylase and lipase, can help differentiate AP from these other considerations. Although serum amylase level is the most commonly used biochemical marker of AP, levels of amylase less than 3 times that of normal levels at the time of diagnosis can be related to rapid clearing. In contrast, serum lipase rises later but may be a more reliable marker of AP because of its longer half-life [16]. Additionally, significantly lower serum amylase and lipase levels have been observed in patients with alcoholic AP, perhaps as a result of poor pancreatic exocrine function [14]. Elevated triglyceride levels are also known to interfere with the serum amylase assay; conversely, both amylase and lipase may be elevated in patients with renal insufficiency without AP [16]. CT abdomen and pelvis without IV contrast can help in making the diagnosis of AP by assessing the presence of peripancreatic stranding and fluid collections. However, stratification of disease severity cannot be performed because of the lack of assessment of pancreatic necrosis. Given the limitations of early CT with or without IV contrast for stratification of disease severity, performing both CT abdomen and pelvis without and with IV contrast does not add to the diagnosis of AP, and CT abdomen and pelvis with IV contrast is preferred to exclude other etiologies of abdominal pain.


Acute Pancreatitis

Acute Pancreatitis. Limitations of CT include relatively poor sensitivity for identifying ductal abnormalities, detecting subtle pancreatic parenchymal changes, and identifying noncalcified gallstones and choledocholithiasis. MRI Abdomen For meeting the imaging diagnostic criteria for AP, MRI abdomen without and with IV contrast with MRCP is at least equal and arguably superior to CT, particularly given the higher soft-tissue contrast resolution. Limitations of MRI include greater frequency of motion-related artifacts and a longer imaging time compared with that of CT. This is an important consideration in an acutely ill patient in whom the study may be degraded by large-volume ascites and breathing-related artifacts, especially in the presence of abdominal pain and pleural effusions. Benefits include good sensitivity even without the administration of an IV contrast agent (making it a useful alternative for patients with renal impairment or allergy to iodine-based CT contrast agents). Although MRI without IV contrast with MRCP provides information about the presence of biliary stones and fluid collections, pancreatic necrosis cannot be accurately assessed in the absence of IV contrast. Acute Pancreatitis The MRI findings of AP are typically an enlarged, edematous gland that is low signal on T1-weighted images and high signal on T2-weighted images. MRI can detect trace amounts of peripancreatic fluid, which is high signal on T2-weighted images and offers higher sensitivity than CT for the diagnosis of subtle, early changes of AP [17,18]. MRI is particularly well suited for pregnant women, patients with renal compromise, and younger patients with suspected AP, especially since studies have shown that patients who undergo early CT for AP are more likely to have repeat CT scans during the same admission [6,8].


Acute Pancreatitis

Acute Pancreatitis. MRI has an added advantage for noninvasive evaluation of the pancreatic parenchyma, biliary and pancreatic ducts, adjacent soft tissues, vascular structures, and composition of AP-associated fluid collections in a single examination [17,19,20]. However, MRI abdomen without and with IV contrast with MRCP does not provide coverage and adequate evaluation of the bowel to assess an alternative diagnosis of bowel ischemia, perforation, etc. US Abdomen US is often the first-line imaging modality in most centers for the evaluation of acute abdominal pain because it is reproducible and can be accomplished at the bedside [15]. Approximately 20% of the time, the pancreas demonstrates features of AP on US, including diffuse glandular enlargement, hypoechoic echotexture of the pancreas consistent with edema, and ascites. US can also be useful for the diagnosis of an alternative etiology of abdominal pain, such as acute cholecystitis. However, US is limited by overlying bowel gas or adynamic ileus in the majority of patients with AP [15]. The primary use of US in patients with AP is to identify gallstones or biliary ductal dilatation. US Abdomen with IV Contrast CEUS is emerging as a potential option for focal evaluation of the pancreas, and it is well suited to the evaluation of perfusion with its use of intravascular contrast agents [15]. However, the use of microbubble contrast for this indication is currently not approved by the FDA, so its use would be considered off-label. Furthermore, CEUS is a focused examination, and in patients with an equivocal presentation of pancreatitis for whom diagnoses other than pancreatitis may be possible, a focused examination may be inadequate. Finally, similar to grayscale US, CEUS is limited by bowel gas, which can be particularly problematic in patients with AP and frequently associated paralytic ileus. Acute Pancreatitis Even in cases of severe AP, clinical scoring methods are used to direct patient care independent of imaging in the early phase.


Acute Pancreatitis

Acute Pancreatitis. Frequently used clinical scoring methods include the Ranson, Acute Physiology, Age, and Chronic Health Evaluation (APACHE)-II, Marshall, and the Bedside Index for Severity in AP (BISAP). Imaging is generally not necessary to document local complications in the early phase. This is because, even though pancreatic necrosis is a well-established risk factor for morbidity and mortality, the presence and extent of pancreatic and peripancreatic necrosis may not be reliably demonstrated on imaging before 5 to 7 days into the clinical course because both necrotic and edematous pancreatic parenchyma show heterogeneous enhancement. In addition, the extent of morphologic changes seen on imaging does not correlate well with the severity of organ failure [3]. Furthermore, even if imaging identifies the presence of fluid collections or pancreatic necrosis in the first week, typically no interventions for these complications are pursued in the early phase [3,18]. CT Abdomen and Pelvis Although it is generally not necessary to document local complications in the early phase with imaging, CT abdomen and pelvis with IV contrast is the primary imaging modality used in the assessment of a critically ill patient, particularly if cross-sectional imaging was not obtained earlier in the clinical course for AP diagnosis. CT abdomen and pelvis with IV contrast has shown consistent clinical value in predicting disease severity and outcomes in AP. The CT severity index is an imaging prognosticator based on the combined assessment of peripancreatic fluid collections and the degree of pancreatic necrosis. A higher CT severity index score is associated with increased morbidity and mortality. A modified CT severity index includes extrapancreatic complications (such as ascites) and vascular complications in the grading system. By including these additional factors, the modified CT severity index has a stronger correlation with patient outcome [2].


Acute Pancreatitis

Acute Pancreatitis. CT abdomen and pelvis with IV contrast to evaluate for pancreatic necrosis, is more reliable when performed 5 to 7 days after presentation, as impaired pancreatic perfusion, edema, and pancreatic necrosis evolve over several days and earlier imaging may underestimate necrosis [2,3]. Similarly, CT abdomen and pelvis with IV contrast is also frequently used for the evaluation of acute peripancreatic fluid collections. Most fluid collections develop in the early phase of pancreatitis and approximately half spontaneously resolve. These acute peripancreatic collections do not have a solid component or a discrete wall and are usually found in the lesser sac and anterior pararenal space. They are usually sterile, rarely become infected, and do not typically necessitate early (if any) intervention [18,21]. Moreover, because patients who undergo early CT for AP are more likely to have repeat CT scans during the same admission [6,8], waiting 5 to 7 days to evaluate the severity and complications of AP with CT abdomen and pelvis with IV contrast is recommended, even in patients with suspected severe AP. In the presence of suspicion for severe disease, the utility of CT abdomen and pelvis without IV contrast is limited to the detection of fluid collections as it cannot assess the presence of pancreatic necrosis. Similarly, adding a noncontrast phase by performing CT abdomen and pelvis without and with IV contrast does not add additional diagnostic information. In a severely ill patient who may not be able to stay still through a fairly long MRI without and with IV contrast with MRCP, an MRI without IV contrast with MRCP may be performed, as a motion-degraded MRI may not add additional diagnostic value. An MRI abdomen without IV contrast with MRCP could detect the presence of pancreatic necrosis. Diffusion-weighted imaging may be used as an alternative to contrast to assess the presence of necrotizing pancreatitis in some cases.


Acute Pancreatitis

Acute Pancreatitis. Additionally, MRCP can assist in the diagnosis of delayed passage of choledocholithiasis, potentially avoiding unnecessary ERCP [11]. Acute Pancreatitis US Abdomen Traditional grayscale and color Doppler US is limited in the assessment of AP disease severity, as it cannot reliably distinguish interstitial from necrotizing pancreatitis because it does not allow for the assessment of parenchymal perfusion. US Abdomen with IV Contrast CEUS is emerging as a potential option for focal evaluation of the pancreas, and it is well suited to the evaluation of pancreatic perfusion with its use of intravascular contrast agents [15]. US severity indexes based on CEUS have shown a strong correlation with CT severity index and can be used in its place. Like CT, CEUS evaluation in the acute setting is limited by impaired pancreatic perfusion, edema, and the evolution of pancreatic necrosis over several days. Too-early imaging may underestimate necrosis. As with grayscale US, CEUS is limited by bowel gas, which can be particularly problematic in patients with AP and frequently associated paralytic ileus. US Duplex Doppler Abdomen Color Doppler US is limited in the assessment of AP disease severity because of its inability to reliably assess parenchymal perfusion. Variant 4: Acute pancreatitis. Continued SIRS, severe clinical scores, leukocytosis, and fever. Greater than 7 to 21 days after onset of symptoms. The late phase of AP occurs after the first week and is characterized by local complications, including infection and fluid collections and persistent SIRS [2,3,18]. Mild disease resolves within the first week, so the late phase only applies to patients with moderately severe or severe pancreatitis. Organ failure is likely in the setting of persistent SIRS, and persistent organ failure defines severe AP.


Acute Pancreatitis

Acute Pancreatitis. Persistent organ failure continues to be the main determinant of severity in the late phase; however, local and systemic complications have important implications for management and are characterized by imaging. Imaging plays a major role in the late phase for assessing severity (including identifying the presence and extent of necrotizing pancreatitis and its complications), guiding interventional, endoscopic, or surgical treatment, and monitoring treatment response. Although leukocytosis and fever are clinical hallmarks of infection, imaging is also important for the evaluation of superimposed infection. It is imperative to identify superimposed infection, as the presence of infection within areas of necrosis is associated with an extremely high mortality [3]. The presence and extent of pancreatic and peripancreatic necrosis increases the likelihood of infection and infection within areas of pancreatic necrosis portends an increased risk of death, which is exacerbated by persistent organ failure. By comparison, infected necrosis without persistent organ failure has a lower mortality rate than infected necrosis with persistent organ failure [3,21]. In the absence of infection, patients with peripancreatic (extrapancreatic) necrosis without concomitant pancreatic parenchymal necrosis have a better prognosis than patients with pancreatic parenchymal necrosis. It has been suggested that, given the improved prognosis, extrapancreatic necrosis should be considered a separate clinical entity in AP [25]. In the presence of infection; however, the rates of complication and mortality for patients with only extrapancreatic necrosis are similar to those for patients with pancreatic parenchymal necrosis with or without extrapancreatic necrosis [25].


Acute Pancreatitis

Acute Pancreatitis. In the late phase (after the first week) of moderately severe or severe pancreatitis, local complications fully develop, and it is important to characterize these complications, as they may require different interventions to avoid increased morbidity or mortality. Imaging plays a major role in identifying the presence and extent of pancreatic and peripancreatic necrosis and characterizing local complications in the late phase. CT Abdomen and Pelvis In the acute phase, it may not be possible to differentiate an acute peripancreatic fluid collection from an acute necrotic collection, as they both appear as fluid density on CT. However, after the first week in the late phase, it is easier to distinguish whether a collection is associated with pancreatic or peripancreatic necrosis. Pancreatic necrosis on CT abdomen and pelvis with IV contrast is characterized by single or multiple areas of nonenhancing pancreatic parenchyma, whereas peripancreatic fat necrosis usually appears as a low attenuation collection. False- positive results for pancreatic necrosis using enhancement on CT are due to reversible reduced perfusion and edema or fluid in the pancreatic parenchyma [21]. Infected pancreatic necrosis usually arises in the second to third week, and signs of infection on CT include gas within areas of necrosis or fluid collections. Acute Pancreatitis CT abdomen and pelvis with IV contrast is the most commonly obtained imaging test to detect the presence of peripancreatic collections [26]. Acute peripancreatic fluid collections do not have a solid component and have a density of 0 to 30 HU on CT. They also lack a discrete wall, are usually sterile, and rarely become infected. Although the majority of acute peripancreatic fluid collections are peripancreatic in the lesser sac or anterior pararenal space, some may track down into the pelvis or superiorly into the mediastinum. Therefore, CT of both the abdomen and pelvis may be warranted.


Acute Pancreatitis

Acute Pancreatitis. More than half of acute peripancreatic fluid collections resolve without intervention in the first several weeks, and intervention is rarely pursued to avoid potentially infecting a typically sterile collection. The remaining acute peripancreatic fluid collections that do not resolve become pseudocysts after 4 weeks and are characterized by a fibrous capsule. CT is the most common modality for identifying pseudocysts and their relationship to surrounding structures prior to intervention. Acute necrotic collections are associated with pancreatic or peripancreatic necrosis and contain varying amounts of fluid and necrotic material and are of varying sizes and shapes [3]. On CT, these collections have heterogeneous, varied densities (fluid, fat, and solid material) with no or an incompletely defined wall. It can be challenging to distinguish collections that contain varying amounts of fluid and necrotic debris from pure fluid containing acute peripancreatic fluid collections on CT abdomen and pelvis with IV contrast and necrotic material within collections is often overlooked. The presence of fat globules on CT is usually associated with the presence of large amounts of debris within a collection [26]. MRI and possibly US are better at demonstrating debris and necrotic material within these collections [21,26,27]. Accurate identification of necrotic debris is important for characterization; however, it is particularly important if drainage is considered, as residual, unrecognized debris after standard drainage increases the risk of infection. Acute necrotic collections may also be associated with disruption of the main pancreatic duct within the parenchymal necrosis, and CT has reduced sensitivity for identifying ductal abnormalities. CT abdomen and pelvis without IV contrast can help in the detection of fluid collections that may or may not be infected.


Acute Pancreatitis

Acute Pancreatitis. Although, it cannot assess the presence of rim enhancement, which adds to the specificity of the diagnosis of an infected collection, in the presence of clinical concern, CT abdomen and pelvis without IV contrast can help preprocedural planning. Smaller fluid collections may sometimes be difficult to distinguish from adjacent fluid-filled bowel loops. CT abdomen and pelvis without and with IV contrast does not add to the diagnostic information. MRI Abdomen MRI abdomen without and with IV contrast with MRCP is comparable to CT abdomen and pelvis with IV contrast for the diagnosis of necrotizing pancreatitis [21]. Pancreatic necrosis is identified as areas of low signal compared with the normal increased signal of the pancreas on fat-saturated T1-weighted unenhanced images and as focal regions of nonenhancement with IV contrast. On T2-weighted images, necrosis can be low signal intensity or hyperintense when liquefied. Fluid-sensitive MRI sequences, including T2-weighted imaging and MRCP, are superior to CT for depiction of necrotic debris within fluid collections [21,26], and MRI with MRCP is well suited for evaluation of pancreatic duct disruption, which most commonly occurs as a complication of necrotizing pancreatitis [22]. Necrosis (typically of the central gland) may lead to an isolated, functional, upstream pancreatic segment that is not connected to the downstream pancreatic duct. Collections resulting from continued ductal secretions from viable pancreatic parenchyma in the area of disrupted duct typically fail to spontaneously resolve. Conservative treatment strategies or drainage will most likely fail in the setting of a disconnected pancreatic duct or lead to persistent pancreatic fistula formation; therefore, early diagnosis of this condition leads to reduced morbidity and may mitigate unnecessary drainage procedures.


Acute Pancreatitis

Acute Pancreatitis. MRI abdomen without IV contrast with MRCP provides more definitive evaluation of the contents of peripancreatic fluid collection and pancreatic ductal integrity when compared with CT. Limitations of MRI include motion artifacts that are due to longer scan times (especially in acutely ill patients who are unable to hold still) and decreased sensitivity for the detection of gas bubbles for imaging identification of infection. US Abdomen Traditional grayscale US is limited in the assessment of necrotizing pancreatitis because it does not allow for the assessment of parenchymal perfusion. Transabdominal US is used for characterization of peripancreatic fluid collections by evaluating for internal, necrotic debris. It is particularly helpful for guiding diagnostic and Acute Pancreatitis therapeutic intervention for large pseudocysts; however, it is limited for the identification of small collections [21]. Gas bubbles within pancreatic and peripancreatic fluid collections may be seen on transabdominal US; however, CT is more commonly used for the imaging diagnosis of infection. US Abdomen with IV Contrast CEUS is emerging as a potential option for focal evaluation of the pancreas. CEUS is well suited to the evaluation of pancreatic parenchymal perfusion, given its use of intravascular contrast agents [15]. Although CEUS can also be used to evaluate complications of pancreatitis, such as splenic artery aneurysm [28], evaluation of local complications and extrapancreatic necrosis may be limited by the focal nature of this examination. Similar to grayscale US, CEUS is limited by bowel gas, which can be particularly problematic in patients with AP and frequently associated paralytic ileus. US Duplex Doppler Abdomen Color Doppler US may be combined with traditional grayscale US for evaluation of vascular complications, such as arterial pseudoaneurysms or thrombosis of the portal venous system. Variant 5: Known necrotizing pancreatitis.


Acute Pancreatitis

Acute Pancreatitis. Significant deterioration in clinical status, including abrupt decrease in hemoglobin or hematocrit, hypotension, tachycardia, tachypnea, abrupt change in fever curve, or increase in white blood cells. CT Abdomen and Pelvis The diagnosis of infected necrosis or fluid collection can be suspected clinically and may be confirmed by fine- needle aspiration for culture. Because aspiration introduces the risk of infection, CT abdomen and pelvis with IV contrast may be obtained when infection is suspected clinically to assess for the presence of gas within areas of necrosis or fluid collections; although, this is of limited utility for identifying early infection [29]. Extraluminal pancreatic enzymes in AP can damage adjacent blood vessels, resulting in vasculitis and pseudoaneurysm formation. An abrupt decrease in hemoglobin or hematocrit is suspicious for pseudoaneurysm rupture. Given speed of acquisition, CT abdomen and pelvis with IV contrast with both arterial and venous phase imaging is the preferred imaging modality for assessment of suspected pseudoaneurysm rupture. CT abdomen and pelvis without IV contrast may help in the detection of hemorrhage as high-density fluid without localization of an active source. Similarly, adding a noncontrast phase by performing CT abdomen and pelvis without and with IV contrast does not add additional diagnostic information. MRI Abdomen MRI is well suited for the follow-up of pancreatic collections; however, in most cases, fine-needle aspiration sampling and microbiological examination of the collection is necessary to definitively diagnose infection; although, this method is invasive and carries a risk of secondary infection. More recently, peripheral restricted diffusion on diffusion-weighted imaging and central low apparent diffusion coefficient has been demonstrated to identify the presence of infection within AP-associated collections with higher sensitivity and accuracy than gas bubbles on CT [29].


Acute Pancreatitis

Acute Pancreatitis. However, clinical suspicion and fine-needle aspiration with fluid analysis remain the gold standard for treatment determination. Hemorrhagic fluid collections may be more easily recognized on MRI than CT because of the presence of T1 hyperintense methemoglobin, low-signal-intensity hemosiderin rim on T2-weighted images, and signal abnormalities related to hemorrhage that persist longer on MRI than CT. However, in the setting of an abrupt decrease in hemoglobin or hematocrit, an acute bleeding episode would be suspected, and MRI without and with IV contrast with MRCP is currently limited by longer acquisition times. In these patients, who may be unstable in the setting of an acute bleeding episode, a more rapid CT examination is preferred. US Abdomen Gas bubbles within necrotic collections and pancreatic and peripancreatic fluid collections may be seen on transabdominal US; however, CT is more commonly used for the imaging diagnosis of infection, particularly because it may be challenging to differentiate gas in overlying stomach/bowel from gas in a collection by US. US Abdomen with IV Contrast Although CEUS can be used to evaluate complications of pancreatitis, such as splenic artery aneurysm [28], in the setting of an abrupt decrease in hemoglobin or hematocrit, CT angiography is the preferred imaging modality given its rapid acquisition and vascular mapping for interventional or surgical treatment planning. Acute Pancreatitis US Duplex Doppler Abdomen Color Doppler US may be used with traditional grayscale US for evaluation of vascular complications, such as arterial pseudoaneurysms or thrombosis of the portal venous system. Pseudoaneurysms, which most frequently involve the splenic, gastroduodenal, and pancreaticoduodenal arteries, may be identified on a Doppler US examination; however, in the setting of an abrupt decrease in hemoglobin or hematocrit, CT angiography is the preferred imaging modality for assessment of suspected pseudoaneurysm rupture. Variant 6: Acute pancreatitis.


Acute Pancreatitis

Acute Pancreatitis. Known pancreatic or peripancreatic fluid collections with continued abdominal pain, early satiety, nausea, vomiting, or signs of infection. Greater than 4 weeks after symptom onset. Local complications in AP include pancreatic or peripancreatic fluid collections. The classification of these fluid collections depends on timing and the presence of necrosis. Acute peripancreatic fluid collections usually develop in the early phase of interstitial edematous pancreatitis and may turn into a pancreatic pseudocyst as a delayed (>4 weeks) complication. A pseudocyst has a well-defined wall and does not contain solid material. In necrotizing pancreatitis, a collection in the early phase is an acute necrotic collection and develops into walled-off necrosis, which is surrounded by a detectible capsule, after 4 weeks [3]. Differentiating walled-off necrosis from pseudocysts that do not contain debris has important implications for management, as residual necrotic debris after drainage may lead to secondary infection. Pseudocysts can be drained by simple percutaneous or endoscopic techniques, as they are composed almost exclusively of fluid. Conversely, walled-off necrosis requires surgical debridement, direct endoscopic necrosectomy, insertion of larger caliber metallic cystgastrostomy stents, or ongoing percutaneous irrigation and drainage of necrotic debris [30]. Although increased clinical severity, particularly persistent organ failure, may suggest that collections likely intervention planning/selection are best represent walled-off necrosis, definitive characterization and accomplished with imaging. CT Abdomen and Pelvis CT of the abdomen and pelvis with IV contrast is historically the most commonly obtained initial test to evaluate the presence of pancreatic or peripancreatic fluid collections. It is also often used to follow-up symptomatic collections and for intervention planning. However, CT is limited in the quantification of debris and differentiation of pseudocysts from walled-off necrosis.


Acute Pancreatitis

Acute Pancreatitis. The best indication of debris containing collections on CT is increased frequency of fat density globules within the collections. The absence of fat globules within a collection does not exclude the possibility of necrosis; however, the presence of fat globules suggests a debris- containing, necrotic collection [26]. CT abdomen and pelvis with IV contrast is useful for detection of an infected collection, which has the imaging features of an enhancing wall and gas bubbles within the collection. However, air bubbles may not be seen with an infected collection, and the diagnosis is ultimately made by fine-needle aspiration and fluid analysis. CT abdomen and pelvis with IV contrast may also be helpful in the detection of a fistulous communication between a fluid collection and an adjacent bowel loop. CT abdomen and pelvis without IV contrast can help diagnose the presence of large fluid collections that may be symptomatic and may help in preprocedural planning if percutaneous drainage or cyst gastrostomy is contemplated. Smaller fluid collections may sometimes be difficult to discern between fluid-filled bowel loops on an examination performed without IV contrast. Fluid collections are identifiable on a CT abdomen and pelvis examination performed with IV contrast and adding a noncontrast phase by performing CT abdomen and pelvis without and with IV contrast does not add additional diagnostic information. MRI Abdomen The contents of pancreatic and peripancreatic collections can be most accurately assessed by fluid sensitive MRI sequences on MRI abdomen without IV contrast with MRCP. T2-weighted imaging provides superior soft-tissue differentiation when compared with CT and allows for more consistent quantification of debris. As such, MRI is more useful for predicting whether these collections can be drained by endoscopic, percutaneous, or surgical drainage procedures.


Acute Pancreatitis

Acute Pancreatitis. Therefore, when imaging is considered for evaluation of symptomatic organized pancreatic or peripancreatic fluid collections, particularly when intervention is contemplated, MRI should be considered in place or as a follow-up to a contrast-enhanced CT [31]. MRI abdomen without and with IV contrast with MRCP is also well suited for evaluation of pancreatic duct disruption, which most commonly occurs as a complication of necrotizing pancreatitis [22]. Necrosis (typically of the central gland) may lead to an isolated, functional, upstream pancreatic segment that is not connected to the Acute Pancreatitis downstream pancreatic duct. Conservative treatment strategies or drainage will most likely fail in the setting of a disconnected pancreatic duct or lead to persistent pancreatic fistula formation; therefore, early diagnosis of this condition leads to reduced morbidity and may mitigate unnecessary drainage procedures. MRI with MRCP provides more definitive evaluation of pancreatic ductal integrity when compared with CT. Visualization of the pancreatic duct may be improved by using a synthetic analog of the hormone secretin, which is sometimes administered to augment the MRCP. Furthermore, although ERCP is considered the gold standard for detection of pancreatic ductal disruption, MRI abdomen without and with IV contrast with MRCP has the advantage of being able to evaluate both the main pancreatic duct and the pancreatic parenchyma simultaneously, as compared with combining CT abdomen and pelvis without and with IV contrast with ERCP. MRI abdomen without and with IV contrast with MRCP also avoids the potential complications associated with ERCP, such as post-ERCP pancreatitis [26,32].


Breast Imaging of Pregnant and Lactating Women.  Introduction/Background Pregnancy-associated breast cancer (PABC) is defined as breast cancer diagnosed during pregnancy, throughout the first postpartum year, or during lactation [1-4]. With a reported incidence of 1 in 3,000 to 10,000 pregnancies, breast cancer is the most common invasive cancer diagnosed during pregnancy [5-10]. Representing up to 3% of all breast cancer diagnoses, PABC is increasing as more women delay child bearing into the fourth decade of life when the incidence of breast cancer is higher [7,10,11]. Breast imaging during pregnancy and lactation is challenging because of the unique physiologic and structural breast changes that increase the difficulty of clinical and radiological evaluation and the need to balance both maternal and fetal well-being. Throughout pregnancy, there is an increase in the size and number of breast ducts and lobules, an increase in the fluid content of the breast, and involution of stromal adipose tissue [9,12]. After delivery, prolactin stimulates secretory changes and the lobular acini become distended with milk [9,13-15]. These physiologic changes lead to increased breast volume, firmness, and nodularity, thereby making the detection of palpable abnormalities on clinical examination more difficult. As a result, there is often a delay in the diagnosis of PABC, and women typically present with more advanced disease exhibiting larger tumors and a higher likelihood of axillary nodal disease compared to nonpregnant women of the same age [8,16]. There is ongoing controversy as to whether delayed diagnosis and young patient age account for the poor prognosis of PABC, or if there may be additional factors causing increased biologic aggressiveness of gestational breast cancer when matched for age and stage [17-19].


Breast Imaging of Pregnant and Lactating Women. Significant vascular and stromal remodeling is necessary to support the expanded epithelium of pregnancy and lactation, and these changes in the breast microenvironment could potentially be leveraged by breast cancer cells, leading to an increase in biologic aggressiveness [2,18,20]. Despite the long-term decreased risk of breast cancer with pregnancy, there are some data to suggest that there may be a transient increased risk for breast cancer during pregnancy and lactation [6]. Some studies show that women with BRCA gene mutations are overrepresented in PABC, and pregnant and lactating women are more likely to have hormone-negative breast cancer than age-matched controls [7,18,21,22]. Although the underlying cause for these observations is not clear, they support the possibility that the tumor biology of PABC is more aggressive than non-PABC breast cancer in young women with equivalent stage and prognostic factors. The most common presentation of PABC is a palpable mass. Therefore, imaging evaluation of a palpable lesion in a pregnant or lactating woman should not be delayed [7,20,23,24]. Less common presenting complaints include focal pain, diffuse breast enlargement, nipple discharge, and, rarely, unilateral milk rejection in which the infant rejects milk from the breast harboring cancer [7,24]. The imaging appearance of PABC is similar to breast cancer in nonpregnant patients. Because of the young age of these women and higher likelihood of triple negative breast cancer, PABC is more likely to demonstrate areas of necrosis[13,25]. In addition, PABC may have a falsely benign appearance presenting as a mass with relatively circumscribed margins, parallel orientation, and posterior acoustic enhancement [1,7]. aDartmouth-Hitchcock Medical Center, Lebanon, New Hampshire. bBeth Israel Deaconess Medical Center, Boston, Massachusetts. cPanel Vice-Chair, NYU Clinical Cancer Center, New York, New York.


Breast Imaging of Pregnant and Lactating Women. dRoper St. Francis Physician Partners Breast Surgery, Charleston, South Carolina; American College of Surgeons. eNorthwestern University Feinberg School of Medicine, Chicago, Illinois; American College of Physicians. fNew York University School of Medicine, New York, New York. gEmory University Hospital, Atlanta, Georgia. hNew York University School of Medicine, New York, New York. iAlpert Medical School of Brown University, Providence, Rhode Island. jBeth Israel Deaconess Medical Center, Boston, Massachusetts. kH. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida. lWomen and Infants Hospital, Providence, Rhode Island; American Congress of Obstetricians and Gynecologists. mMecklenburg Radiology Associates, Charlotte, North Carolina. nDonald and Barbara Zucker School of Medicine at Hofstra/Northwell, Manhasset, New York. oPerelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania. pPanel Chair, Emory University Hospital, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Breast Imaging of Pregnant and Lactating Women Although PABC most commonly presents as a palpable mass, greater than 80% of palpable masses that are biopsied in pregnant and breastfeeding women are benign [10,25]. Benign palpable masses may be due to enlargement of pre-existing benign masses, such as fibroadenomas and hamartomas, or they may represent masses unique to pregnancy and lactation, such as lactating adenomas and galactoceles [9,13].


Breast Imaging of Pregnant and Lactating Women. When pre-existing lesions enlarge because of hormonal stimulation, they may appear atypical secondary to infarction or proliferative and lactational changes within the lesion [9,10,13]. These changes may lead to concerning imaging features and warrant further evaluation with biopsy. Some benign palpable masses are definitively benign on imaging evaluation (ie, cysts), whereas other masses may have benign imaging characteristics that allow for close follow- up. Given the challenge of clinical examination in pregnant and lactating patients, diagnostic breast imaging, particularly breast ultrasound (US), plays a crucial role in characterizing the features of palpable lesions and in determining appropriate management. US has the highest sensitivity for the diagnosis of PABC [24-28]. Furthermore, because of the predominantly young patient age and the decreased sensitivity of mammography in the setting of dense breast tissue, breast US is the first-line imaging examination in pregnant and lactating patients. If breast US is negative, or if there are suspicious sonographic findings, additional imaging with mammography or digital breast tomosynthesis (DBT) may be indicated. There is a limited role for advanced breast imaging techniques in pregnant women. The ACR does not recommend the intravenous (IV) administration of gadolinium during pregnancy [33]. The physiologic increased breast vascularity of pregnancy and lactation may limit the sensitivity of dynamic contrast-enhanced (DCE) breast MRI [12,33-35]. Biopsy should be recommended for any suspicious imaging findings, and patients should be informed regarding the possibility of milk fistula and increased risk of bleeding. Discussion of Procedures by Variant Variant 1: Breast cancer screening during lactation. Initial imaging. There is limited evidence on breast cancer screening in lactating women.


Breast Imaging of Pregnant and Lactating Women. Because of the potential increased risk of breast cancer in this population, consider continued screening during lactation dependent upon the level of underlying risk and the expected duration of lactation. Breast Imaging of Pregnant and Lactating Women There are no studies specifically evaluating DBT in this patient population. The increased breast density seen in younger women and in the hormonally altered breasts of lactating women is more likely to mask small lesions. Therefore, this population may benefit from the ability of 3-D mammography to decrease the masking effect of dense breast tissue. US Breast There are no studies specifically evaluating hand-held or automated whole-breast US screening in women who are breastfeeding. Given the increased mammographic density during lactation, screening US could be considered as a supplemental screening option in lactating women at intermediate and high risk for breast cancer. It is, however, important to keep in mind that screening US may increase the false-positive rate and prompt additional biopsies with small additional risk of milk fistula in lactating women [39,40]. MRI Breast The physiologic increased vascularity of lactation causes a marked increase in background parenchymal enhancement on breast DCE-MRI. Although this may limit the sensitivity for detecting small enhancing masses and nonmass enhancement, studies have shown that breast DCE-MRI can differentiate enhancing breast cancer from background parenchymal enhancement based on kinetics and morphology [19,34,35,38,41]. A study of 53 patients with known PABC demonstrated moderate or marked background parenchymal enhancement in 58% of patients. Despite increased background parenchymal enhancement, there was 98% sensitivity for detection of known PABC; however, it is unknown how many women were lactating at the time of the MRI [19]. There are scant data on MRI screening in lactating women.


Breast Imaging of Pregnant and Lactating Women. In one study, 4 breast cancers in 3 patients were detected on high-risk screening MRI [7]. It may be helpful to wait until 3 months after cessation of breastfeeding. However, if a woman plans to nurse for a long period, or is at very high risk for breast cancer, screening breast MRI during lactation may be considered [10]. The amount of gadolinium excreted in human breast milk over the first 24 hours after IV contrast administration is <1% of the permitted dose for neonates [42]. Up-to-date recommendations with regard to breastfeeding following IV administration of gadolinium are outlined in detail in the ACR Manual on Contrast Media [33]. Therefore, although not the initial imaging tool of choice, screening breast MRI is not contraindicated during lactation and may be considered in lactating women with a high lifetime risk of breast cancer. An informed decision should be made by the mother regarding continuation of breastfeeding after the examination [3,33,42]. Sestamibi MBI There is no role for molecular breast imaging (MBI) in breast cancer screening during lactation. Mammography and DBT Screening mammography can be performed in pregnant women at high risk. Mammography is not contraindicated during pregnancy, and the dose to the fetus is negligible. The fetal radiation dose from a 4-view mammogram is <0.03 mGy. No teratogenic effects have been demonstrated below 50 mGy [43]. Screening mammography is not recommended for pregnant women who are at average or intermediate risk for breast cancer. However, in women who have a high risk of breast cancer, mammographic screening should be considered. There are no studies specifically evaluating DBT in this patient population. The increased breast density seen in younger women and in the hormonally altered breast of pregnant women is more likely to conceal small lesions. Therefore, this population may benefit from the ability of 3-D mammography to decrease the masking effect of dense breast tissue.


Breast Imaging of Pregnant and Lactating Women. Ductal and lobular hyperplasia, combined with increased water content and decreased stromal fat, may increase mammographic density throughout pregnancy. A small study has shown that the anticipated changes in breast density are less pronounced during pregnancy than during lactation, and that most pregnant patients had scattered or heterogeneously dense fibroglandular tissue [44]. Many studies have shown that mammograms may be diagnostic in 74% to 100% of gravid pregnant women [7,24-28]. With current digital techniques and increased Breast Imaging of Pregnant and Lactating Women use of DBT, the ability to detect breast cancer with mammography in pregnant patients may improve. There are several studies that report screen-detected PABC in a small number of patients [7,24]. US Breast Throughout pregnancy, there is progressive ductal and lobular hyperplasia as well as increased duct ectasia. These changes lead to prominent hypoechoic ducts and lobules with diffuse decreased breast echogenicity [9,10]. There are no studies available at this time evaluating the use of screening whole-breast US during pregnancy. Despite the physiologic changes that alter the sonographic appearance of the breasts during pregnancy, screening whole- breast US may be used as a supplemental screening modality in pregnant women younger than 30 at high risk for breast cancer. It is, however, important to keep in mind that screening US may increase the false-positive rate and prompt additional biopsies. MRI Breast It is well-established that IV gadolinium chelates cross the placenta and enter the fetal circulation. Although there are no reported adverse fetal effects due to IV gadolinium in the pregnant mother, there is the potential for the dissociation of free toxic gadolinium ion with limited data in this patient population. Guidelines regarding gadolinium administration during pregnancy are outlined in detail in the ACR Manual on Contrast Media [33].


Breast Imaging of Pregnant and Lactating Women. Because of the concerns regarding gadolinium crossing the placenta and limited data regarding its safety in this setting, screening breast DCE-MRI is not recommended in pregnant women with any breast cancer risk profile. Sestamibi MBI There is no role for MBI in breast cancer screening during pregnancy. Mammography and DBT Mammography is not contraindicated during pregnancy. The fetal radiation dose from a 4-view mammogram is <0.03 mGy. No teratogenic effects have been demonstrated below 50 mGy [43]. There are no studies specifically evaluating DBT in this patient population. The increased breast density seen in younger women and in the hormonally altered breast of pregnant women is more likely to conceal small lesions. Therefore, this population may benefit from the ability of 3-D mammography to decrease the masking effect of dense breast tissue. Ductal and lobular hyperplasia, combined with increased water content and decreased stromal fat, may increase mammographic density throughout pregnancy. A small study has shown that the anticipated changes in breast density are less pronounced during pregnancy than during lactation, and that most pregnant patients had scattered or heterogeneously dense fibroglandular tissue [44]. Many studies have shown that mammograms may be diagnostic in 74% to 100% of pregnant women [7,24-28]. With current digital techniques and increased use of DBT, the ability to detect breast cancer with mammography in pregnant patients may improve. There are several studies that report screen-detected PABC in a small number of patients [7,24]. US Breast Throughout pregnancy, there is progressive ductal and lobular hyperplasia as well as increased duct ectasia. These changes lead to prominent hypoechoic ducts and lobules with diffuse decreased breast echogenicity [9,10]. There are no studies available at this time evaluating the use of screening whole-breast US during pregnancy.


Breast Imaging of Pregnant and Lactating Women. Despite the physiologic changes that alter the sonographic appearance of the breasts during pregnancy, screening whole- breast US may be used as a supplemental screening modality in pregnant women between 30 and 39 years of age with a high risk of breast cancer. It is, however, important to keep in mind that screening US may increase the false-positive rate and prompt additional biopsies. MRI Breast It is well established that IV gadolinium chelates cross the placenta and enter the fetal circulation. Although there are no reported adverse fetal effects due to IV gadolinium in the pregnant mother, there is the potential for the Breast Imaging of Pregnant and Lactating Women dissociation of free toxic gadolinium ion with limited data in this patient population. Guidelines regarding gadolinium administration during pregnancy are outlined in detail in the ACR Manual on Contrast Media [33]. Because of the concerns regarding gadolinium crossing the placenta and limited data regarding its safety in this setting, screening breast DCE-MRI is not recommended in pregnant women with any breast cancer risk profile. Sestamibi MBI There is no role for MBI in breast cancer screening during pregnancy. Mammography and DBT Mammography is not contraindicated during pregnancy. The fetal radiation dose from a 4-view mammogram is <0.03 mGy. No teratogenic effects have been demonstrated below 50 mGy [43]. There are no studies specifically evaluating DBT in this patient population. The increased breast density seen in younger women and in the hormonally altered breast of pregnant women is more likely to conceal small lesions. Therefore, this population may benefit from the ability of 3-D mammography to decrease the masking effect of dense breast tissue. Ductal and lobular hyperplasia, combined with increased water content and decreased stromal fat, may increase mammographic density throughout pregnancy.