Sigal R, Zagdanski A M, Schwaab G, Bosq J, Auperin A, Laplanche A, Francke J P, Eschwège F, Luboinski B, Vanel D
Department of Radiology, Institut Gustave Roussy, Villejuif, France.
Radiographics. 1996 Jul;16(4):787-810. doi: 10.1148/radiographics.16.4.8835972.
Because contemporary treatment of oral cavity cancer involves procedures that spare the tongue and mandible, an adequate assessment of the oral cavity is essential for appropriate surgical and radiation therapy planning. Computed tomography (CT) and magnetic resonance (MR) imaging, which allow differentiation between soft tissues, are valuable tools for assessing this complex region. Their main advantage resides in their capacity to show at best the normal anatomy and the exact extent of a low-lying tumor. For display of soft tissues and tumor, MR imaging, being a multiplanar and multicontrast technique, is superior to CT. Nonenhanced T1-weighted MR imaging is better for defining the exact extent of medullary bone invasion, which appears as a low-signal-intensity area within hyperintense medullary fat. CT is optimal in detection of cortical bone invasion, which appears as an interruption or erosion of the peripheral hyperattenuating rim. Thus, in cancer of the tongue, MR imaging should be performed first. If tumor extension to the mandible is suspected (due to clinical or MR imaging findings), CT should be added. In cancer of the floor of the mouth, both MR imaging and CT should be performed in the initial work-up, especially in those cases in which there is a clinical doubt about mandibular extension of disease. The main drawback of both modalities is their lack of specificity; other methods are needed to discriminate between tumors and inflammatory or infectious diseases, particularly in the mandible. However, once the diagnosis has been confirmed histologically, treatment can be chosen based on complementary information obtained from CT and MR imaging.
由于当代口腔癌治疗涉及保留舌和下颌骨的手术，因此对口腔进行充分评估对于制定合适的手术和放射治疗方案至关重要。计算机断层扫描（CT）和磁共振（MR）成像能够区分软组织，是评估这一复杂区域的重要工具。它们的主要优势在于能够最佳地显示正常解剖结构以及低位肿瘤的确切范围。对于软组织和肿瘤的显示，作为多平面和多对比技术的MR成像优于CT。非增强T1加权MR成像更有助于确定髓质骨侵犯的确切范围，在高信号的髓质脂肪内，髓质骨侵犯表现为低信号强度区域。CT在检测皮质骨侵犯方面最为理想，皮质骨侵犯表现为周边高密度边缘的中断或侵蚀。因此，对于舌癌，应首先进行MR成像。如果怀疑肿瘤侵犯下颌骨（基于临床或MR成像表现），则应加做CT。对于口底癌，在初始检查时应同时进行MR成像和CT检查，尤其是在临床上怀疑疾病侵犯下颌骨的病例中。这两种检查方式的主要缺点是缺乏特异性；需要其他方法来区分肿瘤与炎症或感染性疾病，尤其是在下颌骨部位。然而，一旦组织学确诊，就可以根据从CT和MR成像获得的补充信息来选择治疗方案。
