In a 42-year-old obese woman, cortisol levels in blood, urine and saliva are determined and in all the determinations they are elevated. After performing the nocturnal suppression test with dexamethasone, cortisol levels in blood remain elevated, so ACTH independent Cushing's syndrome is suspected, what additional test would you request to confirm the diagnosis at this time?
Anyway, I think that the clinical case is poorly stated, since before doing the CT scan, ACTH should be measured and, once ACTH is suppressed, the CT scan should be done. But since the question is "what would you do to confirm the diagnosis of suspected ACTH independent Cushing's syndrome", the answer is CT.
A petrosal sinus catheterization.
A gammagraphy with labeled somatostatin (Octreoscan).
A scan with Sesta-MIBI.
An abdominal ultrasound.
An adrenal CT scan.