Adrenal masses: differentiation with chemical shift, fast low-angle shot MR imaging.

Abstract

The purpose of this study was to investigate the efficacy of chemical shift, fast low-angle shot (FLASH) imaging at 1.5 T to differentiate adrenal masses. The materials included patients with adrenocortical adenomas (n = 32), metastatic tumors (n = 17), and pheochromocytomas (n = 4). FLASH images were obtained with breath holding at 100/11 (repetition time msec/echo time msec) (out-of-phase images) and 100/13 (in-phase images) and a flip angle of 20 degrees to differentiate the lipid contents in the adrenal tumors. The signal-intensity (SI) indexes of adrenal masses ([SI on IP - SI on OP]/[SI on IP x 100]), where IP = in-phase image and OP = out-of-phase image, were calculated. All adenomas had SI indexes of more than 5%, while SI indexes of metastatic tumors and pheochromocytomas were less than 5%, with accuracy of 100% in the differentiation between adenoma and nonadenoma. Hyperfunctioning adenoma, however, could not be differentiated from nonhyperfunctioning adenoma. Chemical shift FLASH imaging was superior to the calculated T2 in the characterization of adrenal masses.

Diagnostic utility of diffusion‐weighted MR imaging and apparent diffusion coefficient value for the diagnosis of adrenal tumors

“…Chemical shift images were obtained by double-echo gradient echo sequence (TR ϭ 161 ms, TE ϭ 2.38 ms [out-of-phase, OP] and 4.76 ms [in-phase, IP], FA ϭ 60, slice thickness ϭ 6 -8 mm, interslice gap ϭ 1-2 mm) under breath holdings, and the signal intensity index (SII; [IP-OP]/IP *100%) was calculated from the signal intensities on the IP and OP images by placing ROIs in the adrenal tumors (22,23). ROIs on ADC maps and chemical shift images were drawn as large as possible in each adrenal tumor.…”

Contribuição dos métodos de imagem no estudo das glândulas suprarrenais em pacientes com hiperplasia congênita de suprarrenal, com ênfase nas técnicas quantitativas por ressonância magnética

“…16 Moreover, adrenal MRI imaging in CAH patients showed findings such as normal or diffuse enlarged adrenal glands, 44 adrenal nodules, 16,37,45 and myelolipomas, 46,47 which is consistent with US and CT findings. The size of the adrenal glands and presence of nodules may relate to hormonal control status; a significant correlation between adrenal and nodule sizes and hormonal parameters has been described.…”

Adrenal Imaging

“…Adenomas can be differentiated from metastases using chemical shift MRI [CSMRI] if the patient has an indeterminate adrenal mass on unenhanced CT and is allergic to iodinated contrast or in young patients, in whom radiation exposure is a concern, although with the use of low-dose CT techniques, this is less of an issue [16,17]. Most adrenal adenomas contain sufficient intracellular lipid and lose signal on the out-of-phase (CSMRI) image compared to the spleen.…”