Comparison between normal phase and reverse phase gradient-echo magnetic resonance sequences and conventional spin-echo sequences in the T1-weighted images of focal hepatic lesions

Our objective is to compare normal phase (P) and reverse phase (RP) gradient-echo (GRE) magnetic resonance (MR) sequences with conventional spin-echo (SE) sequences in the detection of focal hepatic lesions in T[-weighted images and to evaluate the utility of chemical shift techniques (P and RP) in the characterization of fatty hepatic lesions. Between June 1992 and March 1995, 162 patients with focal hepatic lesions were studied by MR (1.0 Tesla). Highly T1-Weighted P and RP GRE sequences were achieved using the FLASH technique and were compared quantitatively with SE t[ sequences to assess the detectability of the lesions. A total of 216 lesions were analyzed in three groups of patients: a)patients with healthy livers (n=74, 110 lesions); b) patients with liver cirrhosis (n=76, 85 lesions), and c) patients with fatty liver (n=12,21 lesions). The quantitative parameters employed to assess the detectability of lesions were: lesion-to-liver contrast and lesion-to liver contrast-to-noise ratio; the detection of fat in the lesions was based on the percentage of signal intensity variation (SIV) between P and RP images. RP sequences showed significantly greater lesion-to-liver contrast in healthy and cirrhotic livers (p<0.001). P sequences showed significantly greater lesion-to-liver contrast and lesion-to-liver contrast-to-noise ratio in the fatty liver(p<0.001). There were no statistically significant differences among RP, P and SE sequences with respect to the lesion-to-liver contrast-to-noise ratio in cirrhotic livers (P<0.28). The chemical shift technique detected fat in 21 lesions (9.7%, mean SIV: 191.1%; sensitivity 100% when compared with fine needle aspiration biopsy. (Author) 23 refs