DIAGNOSTIC-VALUE OF MAGNETIC-RESONANCE-IMAGING FOR MALIGNANT-TUMORS IN THE ORAL AND MAXILLOFACIAL REGION

The purpose of this study was to clarify the diagnostic value of magne tic resonance imaging for malignant tumors in the oral and maxillofaci al region. Computed tomography and magnetic resonance images of 25 pat ients with malignant tumors of the oral and maxillofacial region were evaluated. Computed tomography scans were performed with intravenous c ontrast enhancement. A 0.2-Tesla (Hitachi Medical Corp., Tokyo, Japan) permanent magnetic resonance unit was used to obtain T1-, T2-, and pr oton-density-weighted images with spin-echo pulse sequences. Gadoliniu m-diethylene-triamine-pentaacetic acid was administered in 11 cases. S evere artifacts influencing image interpretation were observed in 10 ( 40%) cases on computed tomography but only in 5 (20%) cases on magneti c resonance imaging. There was no difference in the detectability of b one invasion between images from the two systems. Contrast enhancement with gadolinium-diethylene-triamine-pentaacetic acid provided additio nal useful information in only 3 of 11 cases compared with nonenhanced magnetic resonance images. Malignant tumors showed a higher signal in tensity than that of muscle on T2-weighted images in all cases and on proton-density-weighted images in 23 (92%) cases. On T1-weighted image s, an intermediate signal intensity similar to that of muscle was seen in 16 (64%) cases and a hyperintense signal in 9 (36%) cases. There w as poor correlation between signal intensity and pathologic diagnosis of the tumors. These results suggest that in cases with severe artifac ts that disturb the interpretation of the images on computed tomograph y, magnetic resonance examinations are preferable for defining the exa ct extent of the primary lesion.