T1-WEIGHTED 3-DIMENSIONAL MAGNETIZATION-TRANSFER MR OF THE BRAIN - IMPROVED LESION CONTRAST ENHANCEMENT

PURPOSE: We developed and evaluated clinically T1-weighted three-dimen sional gradient-echo magnetization transfer (MT) sequences for contras t-enhanced MR imaging of the brain. METHODS: A short-repetition-time, radio frequency-spoiled, 3-D sequence was developed with a 10-millisec ond MT pulse at high MT power and narrow MT pulse-frequency offset, an d the enhancing lesion-to-normal white matter background (L/B) and the contrast-to-noise (C/N) ratios on these images were compared with tho se on T1-weighted spin-echo images and on non-MT 3-D gradient-echo ima ges in a prospective study of 45 patients with 62 enhancing lesions. I n the 24 patients who had intracranial metastatic disease, the number of lesions was counted and compared on the three types of images. RESU LTS: The MT ratio of normal callosal white matter was 55% on the MT 3- D gradient-echo sequences, The L/B and C/N on the MT 3-D gradient-echo images were more than double those on the 3-D gradient-echo images, a nd were significantly greater than those on the T1-weighted spin-echo images, In patients with metastatic disease, the MT 3-D gradient-echo images showed significantly more lesions than did the T1-weighted spin -echo or 3-D gradient-echo images. CONCLUSION: MT 3-D gradient-echo MR imaging improves the contrast between enhancing lesion and background white matter over that obtained with conventional T1-weighted 3-D gra dient-echo and spin-echo imaging. MT 3-D gradient-echo imaging provide s practical sampling, image coverage, and spatial resolution attribute s that may be advantageous over MT T1-weighted spin-echo techniques.