Adrenal Basics

Question 1

A benign adrenal adenoma on CT is consistent with what HU?

What is the parameters to know for contrast washout?

Answer 1

Hounsfield units < 18

Washout >60% at 15 minutes

Question 2

A benign adrenal adenoma shows what on MRI scan

Answer 2

chemical shift imaging; i.e “out of phase” imaging or drop in signal intensity > 20%

Question 3

Pheochromocytoma looks like what on CT scan?

Answer 3

Looks like an adrenal adenoma. Need additional functional studies.

Question 4

Pheochromocytoma appears best on which MRI parameter?

Answer 4

It has high signal intensity on T2-weighted images (i.e. it is bright, similar to CSF and gallbladder on T2-weighted)

Question 5

What specific scan is used to evaluate metastatic pheochromocytoma or a pheo of unknown origin?

What are some common medications that interfere with this test?

Answer 5

MIBG (metaiodobenzylguanidine) scan

• opioids, tramadol, TCAs, ACEI’s, antipsychotics

Question 6

What imaging findings hint you to suspecting an adrenocortical carcinoma?

Answer 6

Larger, and also functional tumors
Venous tumor extension (may need MRI to better characterize)
Calcifications
Cysts (more likely cancerous vs. renal cysts)

Question 7

Given certain sizes of adrenal masses, what are the percent chances of malignancy is an adrenal incidentaloma is 4cm, 4-6cm, and >6cm?

Answer 7

4 cm: < 2%

4-6 cm: 6%

> 6 cm: >25%

Question 8

What imaging findings are correlative for a myelolipoma?

Answer 8

CT scan: fatty tumor = negative Hounsfield units

MRI: fat = high signal intensity on T1 weighted imaging
** bone marrow elements = low T1 signal, moderate T2 signal