Yasumoto M, Shibuya H, Takeda M, Korenaga T
Department of Radiology, Tokyo Medical and Dental University, Japan.
AJR Am J Roentgenol. 1995 Apr;164(4):981-7. doi: 10.2214/ajr.164.4.7726062.
The purposes of this study were to describe the characteristics of squamous cell carcinomas of the oral cavity on unenhanced and contrast-enhanced T1-weighted spin-echo (SE) MR images and unenhanced T2-weighted fast spin-echo (FSE) MR images and to determine which sequences best delineate the margins and extent of the tumors.
Forty-four patients with proved squamous cell carcinoma of the oral cavity (tongue, 24; floor of mouth, seven; buccal mucosa, four; maxillary gingiva, two; and mandibular gingiva, seven) underwent unenhanced axial T2-weighted FSE MR imaging and unenhanced and enhanced axial and coronal T1-weighted SE MR imaging. The appearance, signal characteristics, and extent of the tumors were assessed, and the delineation of tumor margins with each sequence or combination of sequences was evaluated by use of a grading system ranging from 1 (poor) to 3 (excellent). Three patients were excluded because of artifacts on the MR images caused by dental restorations.
Tumors in all 41 patients were depicted on unenhanced T1-weighted SE images, but in four patients, tumors were not visible on T2-weighted FSE images. Except for tumors that invaded the maxillary gingiva, the tumors generally had homogeneous, low signal intensity on unenhanced T1-weighted images and nonhomogeneous, high signal intensity on T2-weighted FSE images. All tumors showed enhancement, 76% with a nonhomogeneous appearance. The delineation 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-enhanced T1-weighted images in 18 cases, for the combination of unenhanced T1-weighted and T2-weighted FSE images in five cases, and for T2-weighted FSE images in one case. In three cases, the highest rating was given for both combinations of pulse sequences.
An unenhanced T1-weighted sequence should be used as the basic pulse sequence for MR imaging of tumors of the oral cavity. When tumor margins are not clearly delineated with this sequence, T2-weighted FSE and contrast-enhanced T1-weighted sequences should be added. Although both of these sequences provide supplementary information, the contrast-enhanced T1-weighted sequence is more useful in delineating the margins and extent of tumors than is the T2-weighted FSE sequence.
本研究的目的是描述口腔鳞状细胞癌在未增强和对比增强的T1加权自旋回波（SE）磁共振成像、未增强的T2加权快速自旋回波（FSE）磁共振成像上的特征，并确定哪种序列能最佳地描绘肿瘤的边界和范围。
44例经证实的口腔鳞状细胞癌患者（舌部24例；口底7例；颊黏膜4例；上颌牙龈2例；下颌牙龈7例）接受了未增强的轴位T2加权FSE磁共振成像以及未增强和增强的轴位及冠状位T1加权SE磁共振成像。评估肿瘤的外观、信号特征和范围，并使用从1（差）到3（优）的分级系统评估每个序列或序列组合对肿瘤边界的描绘情况。3例患者因牙科修复体导致磁共振图像出现伪影而被排除。
41例患者的肿瘤在未增强的T1加权SE图像上均有显示，但4例患者的肿瘤在T2加权FSE图像上不可见。除侵犯上颌牙龈的肿瘤外，肿瘤在未增强的T1加权图像上通常呈均匀低信号强度，在T2加权FSE图像上呈不均匀高信号强度。所有肿瘤均有强化，76%表现为不均匀强化。肿瘤边界的描绘在31例中为优（3级），10例中为良（2级）。10例中对未增强的T1加权图像评价最高，10例中对对比增强的T1加权图像评价最高，18例中对未增强和对比增强的T1加权图像组合评价最高，5例中对未增强的T1加权和T2加权FSE图像组合评价最高，1例中对T2加权FSE图像评价最高。3例中对两种脉冲序列组合评价均最高。
未增强的T1加权序列应作为口腔肿瘤磁共振成像的基本脉冲序列。当用该序列不能清晰描绘肿瘤边界时，应添加T2加权FSE和对比增强的T1加权序列。虽然这两种序列都能提供补充信息，但对比增强的T1加权序列在描绘肿瘤边界和范围方面比T2加权FSE序列更有用。
