T1-WEIGHTED SPOILED GRADIENT-ECHO MR-IMAGING OF FOCAL HEPATIC LESION - COMPARISON OF IN-PHASE VS OPPOSED-PHASE PULSE SEQUENCE

The goal of our prospective study was to compare quantitatively and qu alitatively in-phase and opposed-phase T1-weighted breath-hold spoiled gradient-recalled-echo (GRE) MR imaging technique for imaging focal h epatic lesion. Thirty-eight patients with 53 focal hepatic lesions had in-phase (TR = 12.3 ms, TE = 4.2 ms) and opposed-phase (TR = 10.1 ms, TE = 1.9 ms) GRE (flip angle = 30 degrees, bandwidth +/- 32 kHz, matr ix size 256 x 128, one signal average) MR imaging at 1.5 T. Images wer e analyzed quantitatively by measuring the lesion-to-liver contrast an d for lesion detection. In addition, images were reviewed qualitativel y for lesion conspicuity. Quantitatively, lesion-to-liver contrast obt ained with in-phase (3.22 +/- 1.86) and opposed-phase pulse sequence ( 3.72 +/- 2.32) were not statistically different (Student's t-test). No difference in sensitivity was found between in-phase and opposed-phas e pulse sequence (31 of 53, sensitivity 58% vs 30 of 53, sensitivity 5 7%, respectively). Two lesions not seen with opposed-phase imaging wer e detected with in-phase imaging. Conversely, one lesion not seen on i n-phase imaging was detected on opposed-phase imaging so that the comb ination of in-phase and opposed-phase imaging yielded detection of 32 of 53 lesions (sensitivity 60%). Qualitatively, lesion conspicuity was similar with both techniques. However, in-phase images showed better lesion conspicuity than opposed-phase images in 9 cases, and opposed-p hase images showed better lesion conspicuity than in-phase images in 7 cases. No definite advantage (at a significant level) emerged between in-phase and opposed-phase spoiled GRE imaging. Because differences i n lesion with the two techniques in individual cases, MR evaluation of patients with focal hepatic lesion should include both in-phase and o pposed-phase spoiled GRE imaging.