Characterization of adrenal lesions: comparison of 2D and 3D dual gradient-echo MR imaging at 3 T--preliminary results.

PURPOSE: To retrospectively compare a two-dimensional (2D) and a three-dimensional (3D) technique for in-phase (IP) and opposed-phase (OP) single-breath-hold 3-T magnetic resonance (MR) imaging in the characterization of adrenal lesions, with histopathologic confirmation, computed tomographic findings, or imaging follow-up for a minimum of 6 months used as the reference standard.
MATERIALS AND METHODS: This retrospective HIPAA-compliant study was approved by institutional review board, and a waiver of informed consent was obtained. Thirty-four patients (mean age, 57 years) with 37 adrenal lesions underwent 3-T adrenal MR imaging with both 2D and 3D single-breath-hold dual gradient-echo (GRE) MR sequences. Signal intensity (SI) index and adrenal-to-spleen, adrenal-to-liver, and adrenal-to-muscle SI ratios for each lesion were compared between the two techniques by using repeated-measures analysis of variance. The area under the receiver operating characteristic curve (AUC) for each evaluation method was determined, with retrospective selection of suggested thresholds.
RESULTS: For the 2D and 3D techniques, the mean SI index and SI ratios were significantly different between adenomas and nonadenomas (P < .05), except for the adrenal-to-liver SI ratio with the 2D technique and the adrenal-to-muscle SI ratio with both techniques. For all evaluation methods, the AUCs were higher, although not statistically significant, for the 3D technique. The two techniques exploited different suggested thresholds for discriminating adenomas from nonadenomas.
CONCLUSION: Adrenal adenomas can be readily differentiated from nonadenomas at 3-T MR imaging with either a 2D or 3D single-breath-hold dual GRE MR technique. Depending on the acquisition technique, different suggested thresholds need to be selected for various evaluation methods.