SQUAMOUS-CELL CARCINOMA OF THE ORAL CAVITY - MR FINDINGS AND VALUE OFT1-WEIGHTED VERSUS T2-WEIGHTED FAST SPIN-ECHO IMAGES

OBJECTIVE, The purposes of this study were to describe the characteris tics of squamous cell carcinomas of the oral cavity on unenhanced and contrast-enhanced T1-weighted spin-echo (SE) MR images and unenhanced TS-weighted fast spin-echo (FSE) MR images and to determine which sequ ences best delineate the margins and extent of the tumors, MATERIALS A ND METHODS, Forty-four patients with proved squamous cell carcinoma of the oral cavity (tongue, 24; floor of mouth, seven; buccal mucosa, fo ur; maxillary gingiva, two; and mandibular gingiva, seven) underwent u nenhanced axial T2-weighted FSE MR imaging and unenhanced and enhanced axial and coronal T1-weighted SE MR imaging, The appearance, signal c haracteristics, and extent of the tumors were assessed, and the deline ation of tumor margins with each sequence or combination of sequences was evaluated by use of a grading system ranging from 1 (poor) to 3 (e xcellent), Three patients were excluded because of artifacts on the MR images caused by dental restorations, RESULTS, Tumors in all 41 patie nts were depicted on unenhanced T1-weighted SE images, but in four pat ients, tumors were not visible on Ta-weighted FSE images, Except for t umors that invaded the maxillary gingiva, the tumors generally had hom ogeneous, low signal intensity on unenhanced T1-weighted images and no nhomogeneous, high signal intensity on TS-weighted FSE images, All tum ors showed enhancement, 76% with a nonhomogeneous appearance, The deli neation of tumor margins was excellent (grade 3) in 31 cases and fair (grade 2) in 10 cases, The highest rating was given for unenhanced T1- weighted images in 10 cases, for contrast-enhanced T1-weighted images in 10 cases, for the combination of both unenhanced and contrast-enhan ced T1-weighted images in 18 cases, for the combination of unenhanced T1-weighted and TS-weighted FSE images in five cases, and for T2-weigh ted FSE images in one case, In three cases, the highest rating was giv en for both combinations of pulse sequences, CONCLUSION. An unenhanced T1-weighted sequence should be used as the basic pulse sequence for M R imaging of tumors of the oral cavity. When tumor margins are not cle arly delineated with this sequence, TS-weighted FSE and contrast-enhan ced T1-weighted sequences should be added. Although both of these sequ ences provide supplementary information, the contrast-enhanced T1-weig hted sequence is more useful in delineating the margins and extent of tumors than is the TP-weighted FSE sequence.