HALF-DOSE GADOLINIUM-ENHANCED MR-IMAGING WITH MAGNETIZATION-TRANSFER TECHNIQUE IN BRAIN-TUMORS - COMPARISON WITH CONVENTIONAL CONTRAST-ENHANCED MR-IMAGING

OBJECTIVE. The purpose of this study was to determine whether half-dos e enhanced MR imaging with magnetization transfer (MT) saturation can replace standard-dose enhanced MR imaging without MT saturation in pat ients who have brain tumors, SUBJECTS AND METHODS, Three sets of enhan ced T1-weighted MR images were prospectively obtained for each of 25 p atients with 32 brain tumors; the first conventional MR images without MT were obtained after administration of standard-dose (0.1-mmol/kg) gadopentetate dimeglumine. Within 1 week, patients underwent administr ation of one half-dose (0.05 mmol/kg) of the contrast medium, and then two sets of enhanced T1-weighted images were obtained with and then w ithout MT. The degree of contrast enhancement was assessed qualitative ly for all 32 tumors and quantitatively for 26 tumors, In the quantita tive analysis, we compared mean values for tumor-brain contrast-to-noi se ratios in three sets of images. RESULTS. The visual conspicuity of enhancing lesions in half-dose T1-weighted MR images with MT was compa rable with that of standard-dose conventional T1-weighted MR images in 43% of cases including most extraaxial tumors, In approximately 75% o f cases, the degree of enhancement of the lesions was similar for half -dose T1-weighted images obtained with and without MT, Overall, mean v alues for tumor-brain contrast-to-noise ratios were significantly lowe r in half-dose T1-weighted images with MT than in standard-dose T1-wei ghted images. Also, mean values for tumor-brain contrast-to-noise rati os were significantly higher in half-dose T1-weighted images with MT t han in half-dose T1-weighted images without MT. CONCLUSION. Because ha lf-dose enhanced MR imaging with MT yields enhancement comparable with that of standard-dose enhanced conventional MR imaging in less than 5 0% of cases, the former technique would replace the latter in only lim ited cases such as selected extraaxial tumors.