MR characterization of adrenal masses: field strength and pulse sequence considerations.
The authors evaluated the ability of magnetic resonance (MR) imaging at 1.5 T to characterize 28 adrenal masses, using several variables: signal intensity ratios (adrenal/liver and adrenal/fat) on T2- and T1-weighted images, and the calculated T2 relaxation time of the adrenal mass. Signal intensity ratios were unreliable in distinguishing adenomas from nonadenomas. The calculated T2 relaxation time was more useful: All 15 adrenal masses with a T2 of less than 60 msec were adenomas. A T2 greater than 60 msec was less specific and included six metastases, two pheochromocytomas, one adrenal carcinoma, two adrenal hemorrhages, and two nonhyper-functioning adenomas. Therefore, T2 values are more accurate than signal intensity ratios for characterization of adrenal masses at 1.5 T. The unsuitability of previously published criteria determined with 0.35- and 0.5-T systems may reflect the change of T1 and T2 relaxation times with field strength, altering the relative T1 and T2 weighting by a given pulse sequence.
Kier
R
R
Department of Diagnostic Imaging, Yale University School of Medicine, New Haven, CT 06504.
McCarthy
S
S
D000236:Adenoma / Q000175:diagnosis; D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000556:secondary; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis / Q000556:secondary; D003937:Diagnosis, Differential; D004574:Electromagnetic Fields; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010673:Pheochromocytoma / Q000175:diagnosis / Q000556:secondary