Unselected brain 0.5-T MR imaging: comparison of lesion detection and characterization with three T2-weighted sequences.

Abstract

To compare the diagnostic values of three T2-weighted sequences in unselected brain 0.5-T magnetic resonance (MR) imaging examinations. MR imaging was performed in 102 patients because of neurologic symptoms or the follow up "previously known disease." The protocol comprised three T2-weighted sequences: turbo spin-echo (SE), turbo fluid-attenuated inversion-recovery (FLAIR), and gradient and SE (GRASE) sequences. In a prospective, blinded analysis, sequences were compared quantitatively and qualitative by three independent readers for lesion detection and characterization. Twenty-four patients had normal findings, and 78 had abnormal findings, with 121 final diagnoses. Quantitatively, the "white" cerebrospinal fluid (CSF) sequences, turbo SE and GRASE, had higher contrast-to-noise ratios (CNRs) than the "black" CSF sequence, FLAIR, with respect to the signal intensity of white manner, but lower CNRs than FLAIR with respect to the signal intensity of CSF. Qualitatively, for lesion detection, sensitivity and accuracy were significantly higher for FLAIR than for turbo SE or GRASE (P < .05); there was no statistically significant difference between turbo SE or GRASE. FOR lesion characterization, FLAIR was significantly superior to GRASE and turbo SE for white matter disease (P < .05), superior to only turbo SE (P < .05) for vascular disease, and not superior to GRASE or turbo SE for tumors. The black CSF T2-weighted turbo FLAIR sequence is a useful adjunct to the usual white CSF T2-weighted sequences in unselected brain 0.5-T MR imaging.