USEFULNESS OF FAT-SUPPRESSION MAGNETIC-RESONANCE-IMAGING FOR ORAL ANDMAXILLOFACIAL LESIONS

In magnetic resonance imaging (MRI) of the oral and maxillofacial regi on, where large amounts of fat are normally present, the high signal i ntensity of fat on T1-weighted images (T1WI) and the chemical-shift ar tifact have limited the utility of paramagnetic contrast agents. Elimi nating fat signal by fat-suppression techniques can increase the value of contrast-enhanced MRI. The present study was designed to evaluate the utility and role of chemical-shift imaging for fat suppression in the detection of oral and maxillofacial lesions in 22 patients (17 wit h malignant tumors, two with benign tumors, and three with inflammatio n). The depiction of lesions on the postcontrast fat-suppression T1WI was compared with that of conventional pre- and postcontrast T1 and T2 WI on a four-grade scale (grades 0-3). The postcontrast fat-suppressio n T1WI:(average grade, 2.86) were significantly superior to the precon trast T1WI (0.82) and postcontrast T1WI (1.86) and T2WI (1.68). Postco ntrast fat-suppression T1WI were particularly beneficial in the detect ion of central necrosis or extracapsular invasion of metastatic neck l ymph nodes as well as in defining the lesion extent at fat-containing areas such as the bone marrow or cheek. These findings demonstrated th at the fat-suppression technique is extremely useful in the delineatio n of oral and maxillofacial lesions without increase of the scan time or image postprocessing procedures.