Dr. Alan Wray

- 2-9% population have a non-hyperfunctioning adrenal adenoma
- patients with cancer most small adrenal masses are adenomas
- likelihood of a small, <than 1.5 cm., adrenal mass to be an adenoma almost 100%
in the absence of a known malignancy

Adenoma: 70% lipid rich
30% lipid poor

NECT: lipid rich <10 HU 96-98% specificity
lipid poor, metastasis, etc. >10 HU

CECT: scan at 60-80 sec and then 10 mm. delay
Adenomas typically have relatively rapid washout

Relative:

enhanced CT (HU) — delayed (HIJ)
_____________________________________ x 100%
enhanced CT (HU)

Absolute:

enhanced CT (HU) — delayed (HU)
____________________________________ x 100%
enhanced CT (HU)- unenhanced (HU)

relative washout> 40% adenoma
absolute washout> 60% = adenoma

adenoma washout pattern:

delayed (HU)
________________________________________ x 100%=>50%
enhanced (HU) — unenhanced (HU)

- lipid poor adenoma have similar washout pattern to lipid rich adenomas

MRI: lipid rich T1W1 in phase relative hyperintense
T1W1 out of phase- signal drop out

PET: - typical adenoma is negative (activity <than liver) although there are false
positives i.e. some adenomas are positive

- mets and CA typically positive although there are false negatives with BAC,
carcinoid, necrosis, blood