T2-weighted MR imaging of the abdomen: fast spin-echo vs conventional spin-echo sequences.

Abstract

The purpose of this study was to compare one optimized T2-weighted fast spin-echo sequence with one T2-weighted conventional spin-echo sequence to determine the impact of fast spin echo on image quality and diagnostic efficacy for evaluation of the abdomen. A total of 32 patients with 43 lesions involving various abdominal organs were examined. T2-weighted fast spin-echo (4000/119/4, echo train length = 16, matrix = 256 x 256) and T2-weighted conventional spin-echo (3400-3800/80/2, matrix = 128 x 256) images were compared qualitatively and quantitatively to determine whether the two types of images differed with respect to tissue contrast, conspicuousness of lesions, image quality, and artifacts. The signal intensity of all abdominal structures (except gallbladder and fat) was significantly lower on fast spin-echo images than on conventional spin-echo images. Qualitative liver-to-spleen contrast was significantly reduced on fast spin-echo images, whereas quantitative liver-to-spleen contrast was not significantly different. Blurring of anatomic structures, vascular pulsation, and chemical-shift misregistration artifacts were significantly reduced on fast spin-echo images. The qualitative conspicuousness and contrast-to-noise ratio for all lesions evaluated together were not significantly different (p = .5 and p = .069, respectively) on fast spin-echo vs conventional spin-echo images. However, qualitative conspicuousness and contrast-to-noise ratio of solid lesions were significantly reduced on fast spin-echo images (p = .022 and p = .01, respectively). The contrast-to-noise ratio of cystic lesions was significantly better (p = .002) on fast spin-echo images than on conventional spin-echo images. Although the fast spin-echo protocol used in this study provides better image quality and contrast-to-noise ratio for cystic abdominal lesions than does conventional spin echo, the qualitative conspicuousness and contrast-to-noise ratio of solid abdominal lesions are decreased. Fast spin echo provides high-quality images with fewer artifacts in significantly less time than is possible with conventional spin-echo images. Further evaluation is necessary to determine the optimal protocol for T2-weighted fast spin-echo MR imaging of the abdomen.