Detection of microscopic fat in adrenal adenomas: comparison of 2D dual gradient-echo MRI and 3D two-point Dixon...

BackgroundLimited data exist comparing the detection of microscopic fat in adrenal adenomas on two-dimensional chemical shift dual-echo (2D CSI) magnetic resonance imaging (MRI) and three-dimensional two-point Dixon techniques (3D Dixon).PurposeTo compare the sensitivity of 2D CSI versus 3D Dixon techniques for the diagnosis of adrenal adenomas.Material and MethodsA retrospective analysis was conducted of 33 patients with adrenal masses who underwent both 2D CSI and 3D Dixon sequences on a 1.5-T scanner. Two blinded radiologists measured and calculated signal intensity (SI) index (SII) (100×(SI in phase - SI out of phase)/SI in phase) of nodules on each technique. Reference standard diagnosis of 30 adrenal adenomas was established. Sensitivity for adrenal adenoma diagnosis was determined using a SII >16.5%.ResultsIn total, 33 nodules were investigated (mean size=22 mm, range=11-55 mm). Of the 30 adenomas, the mean SII on 2D CSI was 48% for reader 1 and 44% for reader 2, compared to 34% on 3D Dixon for both readers (P < 0.001). Sensitivity for the diagnosis of adenoma with 2D CSI was 90% (95% confidence interval [CI]=82-98) for both readers, while 3D Dixon demonstrated a sensitivity of 73% (95% CI=65-82) for reader 1 and 63% (95% CI=55-72) for reader 2.Conclusion2D dual gradient-echo CSI demonstrated a higher sensitivity for the diagnosis of adrenal adenoma than the 3D Dixon technique. Adrenal MRI evaluation of the adrenal glands at 1.5 T should include 2D dual gradient-echo CSI and not rely solely on 3D two-point Dixon techniques for the diagnosis of adrenal adenomas.