腮腺恶性肿瘤的CT表现

目的探讨CT在评价不同病理类型腮腺恶性肿瘤中的作用，并评价U线（通过下颌后静脉最背侧点与颈椎骨同侧最背侧点的连线）在腮腺肿瘤定位中的应用价值。资料与方法回顾性分析32例经病理证实的腮腺原发恶性肿瘤的CT表现，并用U线定位分析其中经手术治疗的27例肿瘤的深浅叶划分结果。结果（1）低度恶性腮腺上皮源性肿瘤表现为边界清晰或部分清晰、形态较规则、常见小片状坏死区的肿块，强化明显，较少累及两叶。（2）中高度恶性腮腺上皮源性肿瘤表现为边界不清晰、形态不规则、密度均匀或较大片的坏死区的肿块，强化较明显，常累及两叶并浸润周围组织，淋巴结转移多见。（3）非上皮源性恶性淋巴瘤表现为密度均匀、边界清楚、常单侧或双侧多发的肿块，轻度强化。（4）使用U线分析，腮腺肿瘤定位的符合率为70．4％。结论CT在区分不同生物学行为及组织学类型的腮腺恶性肿瘤上有一定的作用。U线在恶性腮腺肿瘤的定位评价中有一定的局限性，综合茎突乳突问区及下颌后静脉受侵情况，评价则更准确，符合率可提高到88．9％。

CT Manifestation of Malignant Tumor of the Parotid Gland

Objective To evaluate the significance of U line (connecting the most dorsal point on the ipsilateral half of a vertebra to the dorsal side of the retromandibular vein) to define the extension of parotid tumor, as well as the value of CT to assess the malignant parotid tumor in different pathological subtype. Materials and Methods CT appearances of 32 cases with primary malignant parotid tumor proved by pathology were analyzed, the "U" line was used to define the location (deep or superficial lobe) of the parotid tumor. Results (1)Low-grade epithelial parotid carcinomas were appeared as mass with clear or partly clear boundary, regular in shape, patchy of necrosis, the tumor were markedly enhanced and rarely bilaterally involvement. (2)Medium and high-grade malignant parotid tumor usually had ill-defined margin, irregular in shape, large patchy necrosis with markedly enhancement, always bilateral involvement and infiltration of adjacent structure as well as lymph node metastasis. (3)Malignant lym-phomas were appeared as multiple masses of homogeneous density and well-defined, unilateral or bilateral involvement with slight enhancement. (4)The accuracy of U line in defining the extension of parotid tumor was 70.4% . Conclusion CT plays an important role in diagnosis of malignant parotid tumor of different biological behavior and histological subtype. U line has limitation in evaluating the malignant parotid tumor, accuracy can be improved to 88.9% with the combination of evaluating involvement of sty-loid-mastoid space as well as the retromandibular vein.