MR-IMAGING OF THE LIVER - COMPARISON BETWEEN SINGLE-SHOT ECHO-PLANAR AND HALF-FOURIER RAPID ACQUISITION WITH RELAXATION ENHANCEMENT SEQUENCES

PURPOSE: To evaluate single-shot T2-weighted magnetic resonance sequen ces and their role in clinical practice in patients with hepatic lesio ns. MATERIALS AND METHODS: Prospective comparison of echo-planar and h alf-Fourier rapid acquisition with relaxation enhancement (RARE) imagi ng was performed in 80 patients with focal hepatic lesions. Spin-echo (SE) single-shot echo-planar (echo times, 47 and 80 msec) and half-Fou rier RARE (echo time, 59 msec) images were compared with turbo SE (rep etition time msec/echo time msec = 3,200-7,600/90) images. Quantitativ e, qualitative, and receiver operating characteristic (ROC) analyses w ere performed. RESULTS: For liver, signal-to-noise ratios on half-Four ier RARE images were significantly higher than those on echo-planar im ages (P < .01). For cystic lesions, contrast on half-Fourier RARE and echo-planar images was slightly higher tan that on turbo SE images. Fo r solid lesions, contrast on echo-planar images was better than that o n half-Fourier RARE or turbo SE images. Artifacts including ghosting, bowel motion, susceptibility difference, and chemical shift were negli gible on half-Fourier RARE images in all patients, whereas susceptibil ity difference and chemical shift of various degrees were seen on all echo-planar images. On the basis of ROC analyses, tumor detection rate s were significantly higher with half-Fourier RARE and turbo SE images than with echo-planar images (P < .01). CONCLUSION: Echo-planar image s provide sufficient contrast to allow detection of both solid and cys tic masses, but severe artifacts preclude routine use. Half-Fourier RA RE images are free from artifacts (chemical shift and susceptibility) and diagnostic performance with them is similar to that with turbo SE images.