Ultrafast magnetic resonance imaging of the brain

The purpose of this study was to compare the diagnostic efficacy of single shot fast spin echo sequence (SSh-FSE), and single shot GRASE-sequence (SSh -GRASE) to the conventional T-2-weighted fast spin echo-sequence (T-2-FSE) in the imaging of brain disorders. Thirty three patients with high signal i ntensity lesions on T-2-weighted images (n = 28), or intracerebral hemorrha ge (n = 5), were examined on a 1.0 T MR scanner, with 23 mT/m gradient stre ngth. The scan time for the conventional T-2-FSE-sequence was 2 min 57 s, t he scan time for the single shot-FSE-, and single shot-GRASE-sequences was 11 sec, and 17 sec, respectively. Twenty-one patients remained still during the examination, whereas 12 could not stay still with consecutive marked m otion artifacts. Images were reviewed by three radiologists. Lesion conspic uity, image quality, and artifacts were scored on a subjective scale. Signa l-to-noise ratios of lesions and normal tissue and contrast-to-noise ratios (CNR) were measured by region of interest (ROI). In the patient group with out motion artifacts conspicuity for lesions greater than or equal to 5 mm did not show a significant difference on conventional T-2-FSE, single shot- FSE and single shot-GRASE. Detectability of the smaller lesions was signifi cantly inferior on single shot-FSE-, and single shot-GRASE-sequences in art ifact free images. For the patient group with motion artifacts SSh-FSE and SSh-GRASE were markedly superior to the conventional T-2-FSE. Grey-white di fferentiation was better on conventional T-2-FSE. Physiologic ferritin as w ell as pathologic hemosiderin depositions were slightly darker and therefor e better visible on SSh-GRASE than on SSh-FSE. Conventional T-2-FSE showed significantly more artifacts. In conclusion, SSh-FSE and SSh-GRASE imaging can be used for rapid imaging of the brain in those patients who are claust rophobic or in patients with involuntary movements due to extrapyramidal di sorders, as well as in children in whom anesthesia is contraindicated or se dation is not possible. (C) 2000 Elsevier Science Inc. All rights reserved.