Journal List > J Korean Radiol Soc > v.38(4) > 1068163

Lee, Lee, Eun, Jeon, Kim, and Cha: Comparison of GRASE and Turbo Spin Echo Sequences in Brain MR Imaging

Abstract

PURPOSE: The purpose of this study was to evaluate the utility of GRASE images of the brain, which combinegradient echo-EPI and turbo spin echo, and to compare the results with those of the turbo spin echo (TSE)technique. MATERIALS AND METHODS: We analyzed and compared brain MR images obtained in 25 patients betweenOctober, 1996 and January, 1997, both TSE and GRASE techniques. Diagnosis was normal (n=5), infarct orischemia(n=10), intracerebral hemorrhage(n=6), and neoplasm(n=4). TSE and GRASE MR images were obtained using a1.5T Gyroscan ACS-NT(Philips, Netherlands). For qualitative assessment, overall image quality, discriminationbetween cortical gray-white matter and basal ganglia-white matter, lesion conspicuity, and MR artifact wereevaluated using a subjective grading system ranging from 1 to 5(1=TSE better than GRASE, 5=GRASE better than TSE).For quantitative assessment, signal-to nosise ratios (SNRs) were calculated for cortical gray matter, whitematter, basal ganglia, and lesions, and contrast-to nosise ratios (CNRs) were calculated for cortical gray-whitematter, basal ganglia-white matter and lesions-white matter, We measured image acquisition time and RF specificabsorption rate (SAR) on TSE and GRASE. RESULTS: Qualitative assessment showed that overall image quality,discrimination between cortical gray-white matter and basal ganglia-white matter, and lesion conspicuity were notsignificantly different between the two imaging techniques. MR artifact was more frequently seen on GRASE than onTSE. Quantitative assessment showed that the SNR of each brain tissue and lesion was significantly greater on TSEimages than on GRASE. Cortical gray-white matter and basal ganglia-white matter CNRs were significantly greater onGRASE images than on TSE, but lesion-white matter CNR was not significantly different between the two techniques.Image acquisition time was 3 minute 31 second in TSE and 1 minute 12 second in GRASE. SAR was lower in GRASE thanin TSE. CONCLUSION: With regard to MR artifact, GRASE is more sensitive than TSE, but as regards image qualityand lesion distinction, the two modalities show no distinct difference. Since GRASE is superior to TSE for thedetection of hemosiderin, and image acquisition time is three times shorter using GRASE, GRASE might usefully beapplied during the evaluation by MR imaging of certain brain conditions.

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