10.14639/0392-100X-N2090
Objective. To evaluate the diagnostic performance of magnetic resonance (MR) with surface coils in assessing cartilage invasion in recurrent laryngeal carcinoma after carbon dioxide transoral laser microsurgery (CO2 TOLMS).Methods. Two expert head and neck radiologists assessed cartilage invasion (infiltrated or non-infiltrated) in submucosal recurrences of laryngeal carcinoma after CO2 TOLMS: results were compared with histopathological report after salvage laryngectomy.Results. Thirty patients met the inclusion criteria and 90 cartilages were assessed. Overall sensitivity, specificity, and positive and negative predictive values for cartilage infiltration were 76, 93, 72 and 94%, respectively; for thyroid cartilage, the values were 82, 79, 69 and 88% respectively; for cricoid cartilage, all values were 100%; and for arytenoids, the values were 33, 96, 56 and 93% respectively.Conclusions. MR with surface coils was able to detect most thyroid and cricoid infiltration in the complex setting of post-CO2 TOLMS laryngeal carcinoma recurrence. In particular, the optimal performance in assessing cricoid invasion can be valuable in choosing the most appropriate treatment among total laryngectomy, open partial horizontal laryngectomies and non-surgical strategies.
text/xml
1827-675X
2090
en
Cesare Piazza
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
cartilage invasion
Magnetic resonance imaging to assess cartilage invasion in recurrent laryngeal carcinoma after transoral laser microsurgery
Text.Serial.Journal
https://www.actaitalica.it/
42
Laryngology
2022-12-29
2022-03-28
2022-12-29
2023-01-16
531-537
1
Cesare Piazza
2022/12/29
10.14639/0392-100X-N2090
531
Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, University of Brescia, School of Medicine, Brescia, Italy; Unit of Otorhinolaryngology, Head and Neck Cancer, ASST Spedali Civili of Brescia, Brescia, Italy
1827-675X
cartilage invasion
en
537
Magnetic resonance imaging to assess cartilage invasion in recurrent laryngeal carcinoma after transoral laser microsurgery
https://www.actaitalica.it/article/download/2090/892
42
ACTA OTORHINOLARYNGOLOGICA ITALICA 2022;42:531-537; doi: 10.14639/0392-100X-N2090




Laryngology

Magnetic resonance imaging to assess cartilage
invasion in recurrent laryngeal carcinoma
after transoral laser microsurgery
Il ruolo della risonanza magnetica nell’identificazione dell’invasione cartilaginea nelle
recidive di carcinoma laringeo dopo trattamento con microchirurgia laser transorale
Marco Ravanelli1,2, Davide Lancini3, Roberto Maroldi1,2, Alberto Paderno2,3, Paolo Rondi2, Simonetta Battocchio5,
Laura Ardighieri5, Marika Vezzoli4, Francesca Del Bon3, Davide Farina1,2, Cesare Piazza2,3
1
 Unit of Radiology, ASST Spedali Civili of Brescia, Brescia, Italy; 2 Department of Medical and Surgical Specialties, Radiological Sciences, and
Public Health, University of Brescia, School of Medicine, Brescia, Italy; 3 Unit of Otorhinolaryngology, Head and Neck Cancer, ASST Spedali
Civili of Brescia, Brescia, Italy; 4 Biostatistics, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy; 5 Unit of
Pathology, Department of Molecular and Translational Medicine, University of Brescia, ASST Spedali Civili di Brescia, Brescia, Italy


SUMMARY
Objective. To evaluate the diagnostic performance of magnetic resonance (MR) with sur-
face coils in assessing cartilage invasion in recurrent laryngeal carcinoma after carbon di-
oxide transoral laser microsurgery (CO2 TOLMS).
Methods. Two expert head and neck radiologists assessed cartilage invasion (infiltrated
or non-infiltrated) in submucosal recurrences of laryngeal carcinoma after CO2 TOLMS:
results were compared with histopathological report after salvage laryngectomy.
Results. Thirty patients met the inclusion criteria and 90 cartilages were assessed. Overall
sensitivity, specificity, and positive and negative predictive values for cartilage infiltration
were 76, 93, 72 and 94%, respectively; for thyroid cartilage, the values were 82, 79, 69 and
88% respectively; for cricoid cartilage, all values were 100%; and for arytenoids, the values
were 33, 96, 56 and 93% respectively.
Conclusions. MR with surface coils was able to detect most thyroid and cricoid infiltration
in the complex setting of post-CO2 TOLMS laryngeal carcinoma recurrence. In particular,                Received: March 28, 2022
the optimal performance in assessing cricoid invasion can be valuable in choosing the most             Accepted: October 20, 2022
appropriate treatment among total laryngectomy, open partial horizontal laryngectomies
and non-surgical strategies.                                                                           Correspondence
                                                                                                       Paolo Rondi
KEY WORDS: transoral laser microsurgery, magnetic resonance, laryngeal cancer,                         Unit of Radiology, University of Brescia, Spedali
recurrence, cartilage invasion                                                                         Civili di Brescia, piazzale Spedali Civili 1, 25123
                                                                                                       Brescia, Italy
                                                                                                       E-mail: paolo.rondi92@gmail.com
RIASSUNTO
Obiettivo. Valutare la capacità diagnostica della risonanza magnetica nell’identificazione
di invasione della cartilagine laringea nelle recidive sottomucose di carcinoma laringeo                 How to cite this article: Ravanelli M, Lancini D,
dopo chirurgia laser transorale.                                                                         Maroldi R. Magnetic resonance imaging to as-
Metodi. Due radiologi con anni di esperienza in radiologia testa collo hanno valutato l’infil-           sess cartilage invasion in recurrent laryngeal car-
trazione cartilaginea (infiltrata o non infiltrata) nelle recidive sottomucose di carcinoma la-          cinoma after transoral laser microsurgery. Acta
                                                                                                         Otorhinolaryngol Ital 2022;42:531-537. https://
ringeo, i risultati sono stati poi confrontati con il referto istologico dopo laringectomia totale.
                                                                                                         doi.org/10.14639/0392-100X-N2090
Risultati. Trenta pazienti rispettavano i criteri di inclusione, 90 cartilagini sono state valu-
tate. La sensibilità, specificità, valore predittivo positivo e negativo sono stati globalmente
                                                                                                       © Società Italiana di Otorinolaringoiatria
76, 93, 72 e 94%; per la cartilagine tiroide erano 82,79,69 e 88% rispettivamente; per la              e Chirurgia Cervico-Facciale
cartilagine cricoide tutti i valori erano 100%.
Conclusioni. La risonanza magnetica con bobine di superficie è in grado di identificare la                            OPEN ACCESS
maggior parte delle infiltrazioni cartilaginee della cartilagine tiroide e cricoide in un contesto
complesso come quello delle recidive di carcinoma laringeo dopo chirurgia laser transorale. La         This is an open access article distributed in accordance with
                                                                                                       the CC-BY-NC-ND (Creative Commons Attribution-Non-
capacità di predire l’invasione cricoidea potrebbe orientare nella scelta del trattamento ade-         Commercial-NoDerivatives 4.0 International) license. The
guato tra laringectomia totale, laringectomia parziale orizzontale e strategie non chirurgiche.        article can be used by giving appropriate credit and mentio-
                                                                                                       ning the license, but only for non-commercial purposes and
PAROLE CHIAVE: microchirurgia laser transorale, risonanza magnetica, cancro laringeo,                  only in the original version. For further information: https://
recidiva, invasione cartilagine laringea                                                               creativecommons.org/licenses/by-nc-nd/4.0/deed.en




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Introduction                                                    diate T2-signal and restricted diffusion on DWI) (Fig. 1).
                                                                Moreover, MRI is not only aimed at identifying submu-
Carbon dioxide transoral laser microsurgery (CO2 TOLMS)         cosal recurrences, but it also provides crucial information
as defined by the European Laryngological Society (ELS) 1       about their spatial extent. This information is mandatory for
is a well-established treatment option for early (T1-T2) and    planning the appropriate salvage treatment, both non-surgi-
selected T3 glottic tumours 2-5. When compared to open          cal (radiotherapy [RT] or chemoradiotherapy [CRT]) and
surgery, assessment of tumour margins during and after          surgical (repeat CO2 TOLMS, open partial horizontal lar-
CO2 TOLMS is hampered by thermal damage and shrink-             yngectomy [OPHL], or total laryngectomy [TL]). In detail,
age of the small specimens, potentially reaching 29% in         cartilage invasion is one of the crucial aspects governing
its anteroposterior length 6. For this reason, discrimination   the choice of the most appropriate rescue treatment. In fact,
between R0 and R1 margins may be a complex task for the         the frequent presence of cartilage invasion (apart from par-
pathologist, with some arguing that single close/positive       tial infiltration of the arytenoids) excludes further transoral
superficial margins can play a secondary role in defining       procedures; purely thyroid cartilage invasion without prela-
subsequent oncologic outcomes 6,7. Clearly, the influence       ryngeal muscle involvement is still manageable by OPHL
of multiple positive superficial and deep margins may be        Types II and III 13, while massive cricoid cartilage involve-
greater, macroscopically reducing the rate of local control     ment inevitably leads to TL.
of disease. In these patients, because of both the inappro-     Several studies have already demonstrated the effective per-
priate surgical margins and the biologically high risk of       formance of MR in assessing cartilage invasion by primary
cancer recurrence, strict follow-up is mandatory for the        laryngeal tumours 14,15. In contrast, data regarding the accu-
early detection of tumour relapse 8.                            racy of MR in evaluating local recurrences of cartilage inva-
Fibreoptic endoscopy represents the cornerstone of surveil-     sion after CO2 TOLMS are still lacking. In our opinion, this
lance after CO2 TOLMS, since it allows early and real-time      topic is of outmost importance for both the widespread adop-
assessment of new mucosal abnormalities in proximity to         tion of transoral approaches, and the difficulty of correctly
or further from the scar tissue, the presence of submucosal     identifying possible submucosal patterns of recurrence in
bulging and the possible alteration of vocal cord motil-        an already treated anatomic subsite. This is even more true
ity. Furthermore, examination with narrow band imaging          when considering that the spread of deep recurrences may
(NBI) or other bioendoscopic devices provides additional        follow different vectors when compared to primary lesions
diagnostic value, enabling highly accurate assessment of        due to the presence of fibrotic barriers, and because the carti-
the neoangiogenetic patterns associated with persistent/re-     lage signal may be altered by iatrogenic inflammation.
current disease 8-10. At present, follow-up with endoscopy      The aim of the present study was therefore to evaluate the
alone after CO2 TOLMS is considered sufficient for T1           diagnostic performance of MR with surface coils in assess-
and low-risk T2 tumours. However, recurrences may occur         ing cartilage invasion in recurrent laryngeal carcinoma af-
at depth below the post-surgical scar, and may be barely        ter CO2 TOLMS.
visible during fibreoptic examination. In such scenarios,
imaging with computed tomography (CT) or magnetic
resonance imaging (MRI) has been shown to be effective          Materials and methods
in the detection of submucosal recurrences and should be        Patients
performed periodically during the first few years after tran-   Data from patients who underwent open surgery (OPHLs
soral surgery for high-risk T2 and T3 tumours, even in the      or TL) for submucosal recurrence after CO2 TOLMS be-
absence of clinical suspicion 11.                               tween January 2008 and September 2021 were retrieved
According to the literature, MR performed with surface          from our institutional electronic database of patient health
coils may be considered the gold standard for follow-up         records. As per internal standard protocol, patients treat-
of these patients, due to its high spatial resolution and       ed with TOLMS underwent flexible videoendoscopy and
the possibility to implement diffusion-weighted imaging         high-definition NBI bimonthly and MR using surface coils
(DWI) sequences 12. In fact, thanks to its optimal contrast     every 6 months in the first 2 years after surgery. Inclusion
resolution, MRI can easily differentiate post-surgical scar     criteria were: a) availability of an MR study with surface
tissue (characterised by a low signal on T2-weighted se-        coils performed in our institute less than 1 month before
quences and the absence of restricted diffusion on DWI),        salvage surgery, and b) availability of a definitive histo-
oedema/granulation (characterised by a high T2-signal and       pathological report describing the status of the laryngeal
increased water diffusivity on DWI), and recurrence (typ-       cartilage (invaded vs not invaded). Patients with previous
ically nodular in shape, and characterised by an interme-       radiotherapy on the neck were excluded.



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MR technique                                                     Ninety cartilages (30 thyroid, 30 cricoid, and 30 arytenoid)
Imaging studies were carried out using a 1.5 Tesla scanner       were evaluated. Thyroid and arytenoid cartilages were as-
(Magnetom Aera, Siemens, Erlangen, Germany), using small         sessed on the tumour side only. At the final histopatholog-
loop surface coils applied to the patient’s neck. The MRI        ical evaluation, overall, 18 (20%) cartilages were found
protocol included turbo spin-echo (TSE) T2- and T1-weight-       to be infiltrated. Of these, the distribution of cartilaginous
ed sequences with slice thickness of 3 mm or less with high      involvement was: 13/30 thyroid, 3/30 cricoid and 2/30 ary-
matrix number; echo-planar DWI sequences; and volumetric         tenoid cartilages.
sub-millimetric gradient-echo fat-suppressed T1-weighted
sequences (VIBE) after intravenous gadolinium injection.         Image quality evaluation
Patients were instructed not to swallow and to breath gen-       The mean image quality evaluated using the 5-point Likert
tly during sequence acquisition; in uncooperative patients,      scale was 3.5 (standard deviation, 0.97). None of the stud-
standard sequences were replaced by sequences with radial        ies were scored 1. In three cases MRI was integrated with
k-space sampling (BLADE and star-VIBE). Further techni-          CT.
cal details are described in previous papers 12,16.
                                                                 Inter-observer agreement
Image analysis                                                   Cohen’s k value demonstrated good concordance between
MRI studies were retrospectively reviewed by two head            the two radiologists in assessing all cartilages (k = 0.61, 95
and neck radiologists (operators 1 and 2, with 10 and 20         CI 0.4-0.82), thyroid laminae (k = 0.7, 95 CI 0.43-0.97)
years of experience, respectively), blinded to patient identi-   and cricoid cartilages ( k= 0.78, 95 CI 0.37-1), while poor
ty and histopathological reports in order to assess their in-    agreement was found with regards to arytenoids (k = 0.3,
ter-observer variability. Image quality was assessed with a      95 CI -0.1 to 0.7).
5-point Likert scale (1, non-diagnostic; 5, optimal). Radiol-
ogists were asked to assign one of two choices (invaded vs       Diagnostic performance
not invaded) for each cartilage (thyroid, arytenoid, cricoid)    Overall, the number of true positives were 13/90, true neg-
relying on multi-sequence evaluation: discontinuity of cor-      atives were 68/90, false positives were 4/90 and false neg-
tical lining in ossified cartilage and disruption of the nor-    atives were 5/90. Overall sensitivity (Se), specificity (Sp),
mal intracartilaginous signal (in ossified and non-ossified      positive (PPV), and negative predictive values (NPV) were
cartilage) by a tumour-like signal (intermediate intensity in    72% (95% CI 52-86%), 94% (95 CI 88-98%), 76% (95% CI
T2, low intensity in T1, enhancement after gadolinium and        50-93%), and 93% (95% CI 85-98%), respectively. Se, Sp,
restricted water diffusivity in DWI) were considered to be       PPV and NPV for thyroid cartilage infiltration were 82%
signs of invasion; an inflammatory signal (a combination         (95% CI 48-98%), 79% (95% CI 54-94%), 69% (95% CI
of T1 hypointensity, T2 hyperintensity and increased water       47-85%) and 88% (95% CI 68-96%), respectively. Se, Sp,
diffusivity in DWI sequences) within cartilage was discre-       PPV, and NPV for cricoid cartilage infiltration were 100%
tionally considered on a case-by-case basis as an indirect       (95% CI 29-100%), 100% (95% CI 87-100%), 100%, and
sign of infiltration or a non-neoplastic change combining        100%, respectively. Se, Sp, PPV, and NPV for arytenoid
this information with a number of other observations such        infiltration were 33% (95% CI 1-91%), 96% (95% CI 81-
as the presence of adjacent healthy scar tissue, the sharp-      100%), 56% (95% CI 8-92%), and 93% (95% CI 73-98%),
ness of the interface between tumour and cartilage, and the      respectively. Figures 2-4 show a false negative, a false pos-
extent of the contact between tumour and cartilage (Fig. 1).     itive and a true positive case, respectively.

Statistical analysis                                             Discussion
Inter- and intra-observer agreements were tested with the
Cohen’s k coefficient: 0.4-0.6, 0.6-0.8, and 0.8-1 k values      Tumour recurrences after CO2 TOLMS occur in a signifi-
were interpreted as fair, good and optimal concordance,          cant number of patients and may represent both a diagnos-
respectively. Diagnostic performance was evaluated using         tic and a treatment challenge 11,17,18. The ensuing selection
2x2 tables for each cartilage and overall.                       of salvage treatment is based on several patient- and tumu-
                                                                 or-related factors, e.g. local and loco-regional extent of dis-
                                                                 ease, vocal cord motility, history of previous (C)RT, patient
Results                                                          comorbidities, status and compliance. Among the tumour
Patients                                                         variables that may greatly impact the therapeutic choice,
Thirty patients met the above-mentioned inclusion criteria.      cartilage infiltration is one of the most influential; however,



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M. Ravanelli et al.




Figure 1. T2-weighted image (left top), apparent diffusion coefficient (ADC) map (right top), unhenhanced T1-weighted (left bottom), contrast-enhanced T1-
weighted (right bottom). Images show a submucosal recurrence infiltrating thyroid laminae (asterisks). The signal pattern of cartilage-infiltrating tumour includes
T2 intermediate signal, low ADC value, low T1 signal before contrast injection and contrast-enhancement. Arrows show a part of right thyroid lamina with a signal
pattern consistent with chondritis: T2 hyperintensity, high ADC value, low T1 signal before contrast and intense contrast-enhancement.



as a result of the post-surgical anatomic and histopatho-                           clinically evident. Neoplastic thyroid cartilage infiltration
logical changes to the larynx, it is not always easily identi-                      automatically defines a recurrent lesion as a rcT3-4 cancer
fiable, even using state-of-the-art imaging techniques 19,20.                       not amenable to CO2 TOLMS due to its well-known subop-
When occurring in deep visceral (paraglottic and preepiglot-                        timal capability to control intra-cartilaginous margins under
tic) spaces, especially when already treated, tumour recur-                         such circumstances 21. In contrast, a rcT3-4 with thyroid car-
rences may rapidly invade critical anatomic structures, such                        tilage infiltration can be favourably managed using OPHL 22
as the cartilaginous laryngeal framework, before becoming                           or TL based on tumour location, vocal fold motility and pa-



534
                                                                                         MRI to assess cartilage invasion in laryngeal recurrence after TOLS




                                                                                Figure 3. False positive. In this T2-weighted image, a submucosal recur-
                                                                                rence is shown (asterisk), in contact with the anterior inner aspect of the
                                                                                thyroid lamina, whose cortex signal seems to be focally effaced (thick white
                                                                                arrow). The cartilage was considered invaded by both the readers, while histol-
                                                                                ogy excluded infiltration. MRI findings might be the result of a partial volume
                                                                                effect due to intrinsically insufficient spatial resolution.




                                                                                Figure 4. True positive. Images (from top to the bottom T2-weighted, unen-
                                                                                hanced T1-weighted and contrast enhanced VIBE sequences) show an anterior
                                                                                commissural submucosal recurrence, which encroach the anterior extremity of
                                                                                both thyroid laminae. Cortical signal is effaced, and focal abnormal signal is
                                                                                seen within the whole thickness of the cartilage (thick white arrow). Both read-
                                                                                ers considered these findings as indicative of cartilage invasion, which was
Figure 2. False negative. Images show a submucosal nodule (asterisk) in         confirmed by histology.
contact with the right thyroid lamina. Relying on top and middle images (T2-
weighted and unenhanced T1-weighted, respectively), showing a sharp inter-
face between tumour and cartilage, without abnormal signal of the medullary
component, the cartilage was judged as non-invaded by both readers. Never-
theless, contrast-enhanced VIBE (bottom image) shows a focal faint enhance-
ment within the cartilage (white thick arrow), which might be consistent with
partial infiltration. Histology confirmed invasion.



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M. Ravanelli et al.




tient-related factors. Massive laryngeal cartilage invasion is    identifying the elastic cartilage of the arytenoid vocal pro-
at present considered to be a poor prognostic factor for CRT      cesses. However, this is by far the least impacting element
response, while massive cricoid involvement represents a          on the choice of rescue treatment.
contraindication for OPHL, even when applying the most            As far as we know, there are no papers in literature dealing
extended technique of OPHL Type III 22.                           with this clinical scenario not only for MRI, but also when
In a retrospective series of 15 patients treated by salvage       considering other techniques, such as CT (which seems to
TL for recurrences after CO2 TOLMS, Horwich et al. 23             have a worse performance compared to MRI in cartilage
found a high prevalence of cartilage invasion (at the level       infiltration by primary tumours), ultrasound (which is af-
of the thyroid and cricoid in 66% and 60% of patients,            fected by the acoustic barrage in ossified cartilages) and
respectively), probably reflecting the three most frequent        PET-CT (which does not have enough spatial resolution to
areas of failure of tumour control by transoral surgery,          depict focal erosions).
i.e. the anterior commissure (especially in the presence          As mentioned above, the low number of cases, which in-
of transcommissural tumours), the subglottis, and the             fluenced the statistical power of our results, represented the
posterior paraglottic space 5,23. In our series, the rate of      main limitation of this study. However, such a drawback
invaded cartilages was much lower, presumably indicat-            appeared acceptable in order to maintain as homogeneous
ing that recurrences had been detected earlier, thanks to
                                                                  as possible the study cohort (the same surgical and radio-
our proactive policy of systematic imaging follow-up in
                                                                  logical teams), thus limiting treatment and diagnostic bias-
high-risk T2-T3 glottic cancers 11. Supporting such a close
                                                                  es to a minimum. Furthermore, the entity of cartilaginous
radiological follow-up protocol, Marchi et al. showed that
                                                                  infiltration was not graded, and therefore a minimal erosion
improved detection of submucosal recurrences by imag-
                                                                  was counted equally to full-thickness invasion.
ing techniques in patients with an a priori high risk of re-
currence closed the gap in terms of oncological outcomes
in low-risk patients and allowed salvage CO2 TOLMS in             Conclusions
half of the patients due to the prevention of cartilaginous       MR with surface coils was able to detect most thyroid and
tumour infiltration.                                              cricoid infiltrations in the complex setting of post-CO2
The low rate of cartilage invasion in our group of patients
                                                                  TOLMS recurrence. In particular, the optimal performance
may be responsible for the low statistical power of this
                                                                  in assessing cricoid invasion could be valuable for choos-
study. However, it should be underlined that all cricoid
                                                                  ing the most appropriate treatment among TL, OPHL and
infiltrations were correctly identified by both radiologists.
                                                                  non-surgical strategies. Signal changes in thyroid laminae
As rule of thumb, signal abnormalities in the cricoid lam-
                                                                  should be carefully considered on a case-by-case basis, giv-
ina, even though consistent on their own with inflamma-
                                                                  en that even minimal infiltration represents a contraindica-
tion, must be considered as indirect signs of infiltration.
On the other hand, chondritis in the thyroid laminae may          tion for salvage transoral procedures.
be present even in the absence of infiltration and general-
ly should not be considered as an indirect sign of partial        Conflict of interest statement
infiltration 28. In our study, such signal abnormalities in       The authors declare no conflict of interest.
thyroid laminae have been evaluated case-by-case by each
radiologist considering for example the extent of contact         Funding
between the recurrent tumour and lamina. The specificity          This research did not receive any specific grant from fund-
in assessing thyroid laminae infiltration was suboptimal          ing agencies in the public, commercial, or not-for-profit
(79%), given the presence of multiple false positive cases.       sectors.
In contrast, the reported sensitivity of 82% can be judged
as a good result, especially considering that the presence        Author contributions
of false negative cases might be due to microscopic infil-        MR: study design, image analysis and paper writing; DL:
tration, which is far from being detectable by the spatial        paper writing; RM: supervision and paper corrections; AP:
resolution of MR sequences. Finally, a lower performance          paper writing, surgery and post-surgical follow-up; PR: pa-
rate of MR in evaluating arytenoid infiltration was demon-        per editing, relationship with the ethic committee; SB: his-
strated. Even if must be considered that this result could be     topathological reporting; LA: histopathological reporting;
affected by the low rate of arytenoid infiltration (arytenoid     MV: statistical analysis; FDB: surgery and post-surgical
invasion occurred in only two cases), it could be conceived       follow-up; DF: supervision and paper corrections; CP: su-
that very low sensitivity might be related to the difficulty in   pervision and paper corrections.



536
                                                                                         MRI to assess cartilage invasion in laryngeal recurrence after TOLS




Ethical consideration                                                          11
                                                                                    Marchi F, Piazza C, Ravanelli M, et al. Role of imaging in the follow-
This study was approved by the Institutional Ethics Com-                            up of T2-T3 glottic cancer treated by transoral laser microsurgery. Eur
                                                                                    Arch Otorhinolaryngol 2017,274:3679-3686. https://doi.org/10.1007/
mittee (CEB Comitato Etico Brescia) (approval num-                                  s00405-017-4642-4
berNP-4267).                                                                   12
                                                                                    Ravanelli M, Farina D, Rizzardi P, et al. MR with surface coils in
The research was conducted ethically, with all study pro-                           the follow-up after endoscopic laser resection for glottic squamous
cedures being performed in accordance with the require-                             cell carcinoma: feasibility and diagnostic accuracy. Neuroradiology
                                                                                    2013;55:225-232. https://doi.org/10.1007/s00234-012-1128-3
ments of the World Medical Association’s Declaration of
                                                                               13
                                                                                    Succo G, Peretti G, Piazza C, et al. Open partial horizontal laryn-
Helsinki.                                                                           gectomies: a proposal for classification by the working committee
Written informed consent was obtained from each partici-                            on nomenclature of the European Laryngological Society. Eur Arch
pant/patient for study participation and data publication.                          Otorhinolaryngol 2014;271:2489-2496. https://doi.org/10.1007/
                                                                                    s00405-014-3024-4
                                                                               14
                                                                                    Kuno H, Sakamaki K, Fujii S, et al. Comparison of MR Imaging and
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