[T2-dependent sequences in the study of hepatic focal lesions: comparison of the conventional spin echo sequence and the 0.5 T fast spin echo].

T2-weighted spin echo MR images are widely used in the detection and characterization of focal liver lesions. The main pitfall of this technique is its relatively long acquisition time. Fast spin echo sequences can provide the same contrast as conventional T2-weighted SE images in a shorter scanning time. Our study prospectively compared the effectiveness of T2-weighted conventional spin echo (CSE) versus fast spin echo (FSE) sequences in MRI of focal liver lesions. We examined 24 patients with this condition. All lesions were submitted to percutaneous biopsy and to the diagnostic gold standard technique, which was intraoperative US (13 patients), Lipiodol CT (10 patients) or 6-month follow-up (1 patient). MR images were analyzed from both a quantitative (signal-to-noise and contrast-to-noise ratios) and a qualitative viewpoints (overall image quality, lesion detection rate, number of lesions as compared with the gold standard, lesion conspicuity, internal features and the absence of artifacts). There was no statistically significant difference in contrast-to-noise ratio between the two sequences (p = 0.713). In the qualitative analysis, CSE sequences were superior to FSE for overall image quality in 50% of cases, for lesion conspicuity in 41.5% of cases and for internal features and the absence of artifacts in 46% of cases, FSE sequences had a higher detection rate in 17% of cases, even though both types of sequences underestimated the number of lesions in 29% of cases, as compared with the gold standard. To conclude, FSE sequences were inferior to CSE for image quality, lesion conspicuity, internal features and the absence of artifacts. FSE sequences were superior in the detection and characterization of fluid and nearly fluid lesions.