Echoplanar MR imaging for ultrafast detection of brain lesions

OBJECTIVE. We retrospectively evaluated the use of echoplanar imaging for ultrafast detection of brain lesions. MATERIALS AND METHODS. In our retrospective study, 61 patients were imaged with the following echoplanar sequences: single-shot proton density-weighted, single-shot T2-weighted, single-shot T2-weighted high-resolution, multishot proton density-weighted, and multishot T2-weighted. Lesions revealed in these patients ranged from 0.5 to 12.0 cm (mean, 3.7 cm) and were the result of tumor (n = 16), stroke (n = 21), demyelination (n = 18), and toxoplasmosis (n = 2). Four patients had scans with normal findings. Two neuroradiologists who were unaware of pertinent clinical data reviewed the images. The images were retrospectively compared with conventional spin-echo images for diagnosis, sensitivity of lesion detection, and qualitative criteria: subjective image quality, gray and white matter differentiation, lesion conspicuity, delineation of lesion borders, and artifacts. (Artifacts included those caused by motion, susceptibility, pulsation, and ghosting.) Quantitative criteria, including signal-to-noise and signal difference-to-noise measurements, were also evaluated in 40 lesions. RESULTS. Sensitivity for lesion detection was 97% for single-shot echoplanar T2-weighted MR images and 100% for multishot echoplanar T2-weighted MR images. Single-shot echoplanar proton density- weighted MR images had the highest signal-to-noise ratio (91.2 ± 19.3). Echoplanar T2-weighted MR images had the highest signal difference-to-noise (33.8 ± 22.9). Echoplanar sequences were superior to spin-echo sequences regarding motion and pulsation artifacts. Spin-echo sequences lacked susceptibility and ghosting artifacts, and were superior in lesion conspicuity and delineation of lesion borders. CONCLUSION. In this study, echoplanar sequences were as sensitive as conventional spin-echo imaging for the diagnostic assessment of lesions. Echoplanar sequences had a strikingly shorter acquisition time and substantially reduced motion and pulsation artifacts. Echoplanar sequences may be a useful diagnostic tool for use in claustrophobic and unstable patients.