ADRENAL MASSES: CHARACTERIZATIONS WITH CT AND MR IMAGING

Hoda Mahmoud Abd Elwahab* and Saher Mohamed Ismail

ABSTRACT

Background: Adrenal mass are found incidentally in up to 5-8% of patients undergoing CT or MRI examinations for other purposes. The non-invasive characterization of adrenal lesions continues to improve with current cross-section imaging modalities. The aim of this work is to highlight how imaging techniques such as CT densitometry, CT washout and chemical shift MRI characterize the most of adrenal lesions and help in differentiating benign from malignant lesions. Design: Prospective study. Patient and Methods: Twenty-five patients had (26) adrenal lesions. Out of them (24) patients had solitary lesion and only one patient had bilateral adrenal lesions. Un-enhanced CT scan was the initial investigation followed by washout CT if the proper diagnosis couldn’t be reached. Chemical shift MRI was done in (15) cases, while fat saturation was applied in (3) of them. Biopsy was done for 3 cases to confirm the diagnosis. The total imaging results as well as the pathological results were analysed. Result: Twenty six adrenal masses consisted of (10) adenomas, (9) metastases, (3) myelolipomas, (3) pheochromocytomas and (1) cyst. In washout CT, a mean absolute percentage washout (APW) and relative percentage washout (RPW) for adenoma were 74% and 68% respectively. For metastases, were 32% and 20% respectively. In chemical shift MRI, ademomas showed drop of signal intensity on the out of phase relative to the in phase image, in contrast to metastases which showed no drop of signal intensity. Conclusions: Various CT and MR imaging modalities, Proved that CT being the most important and available technique to differentiate benign form malignant adrenal lesions. Identification of benign lesions is warranted to reduce the number of unnecessary surgery and follow-up examinations in such patients.

Keywords: Adrenal mass – Washout CT – Chemical shift MRI.