]> 2026-07-31T07:52:14+00:00 WBR0224 0 en CT of the chest '''Incorrect''' : CT chest is to look for ectopic source of ACTH producing tumour. With undetectable ACTH, this option is ruled out. MRI of the brain '''Incorrect''' : MRI of the brain is to look for pituitary dependent Cushing’s syndrome ( Cushing disease), where ACTH will be elevated or normal. CT of the abdomen '''Incorrect''' : Though CT and MRI are both of equal sensitivity and specificity, MRI is more preferable as it helps in characterization of adrenal tumors. MRI of the abdomen '''Correct''' : MRI of the abdomen is the best option of investigation for adrenal tumors. Inferior petrosal sinus sampling. '''Incorrect''' : Inferior petrosal sampling is required to differentiate ectopic ACTH from pituitary ACTH Cushing’s syndrome. Primary Care Office A 58 yr old postmenopausal woman comes to the clinic for weight gain for the past 2 years. She is a known diabetic and hypertensive on metformin, hydrochlorthiazide and atenolol. She also complaints of tiredness and weakness while climbing stairs and combing. Her weight is 200lbs, height is 5.2” inches, BP: 130/80, HR: 90/min. On physical examination, her extremities are thin when compared to the trunk and her face is round and plethoric. Her abdomen is distended with violaceous striae and there is mild proximal weakness of her lower extremities. Her 24 hr urinary cortisol is three times above the normal and high dose dexamethasone suppression test failed to lower the cortisol levels. Plasma ACTH levels are undetectable. What is the best next step in diagnosis? D Endocrine 2020-10-27T23:49:07Z 2459150.4924421 WBR0224