HRCT和MRI对慢性中耳炎的诊断价值

目的 探讨HRCT及MRI对慢性中耳炎的诊断价值。资料与方法 回顾性分析经病理及临床证实的72例慢性中耳炎的HRCT和MRI表现，并进行对比分析。结果 HRCT显示听小骨链破坏。移位（33/61），中耳乳突骨质破坏（33/61），乳突气房消失（54/61），鼓室及鼓窦黏膜增厚，积液（55/61），乙状窦，鼓室盖破坏及半规管瘘（4/61），HRCT也能显示鼓室内及外耳道异常软组织影，MRI不能显示岩骨细微的骨质结构。渗出性慢性中耳炎显示长T1长T2信号影（10/10）。肉芽肿型中耳炎显示为T1长T2信号影（4/6）或短T1长T2信号影（2/6），增强后明显强化，胆脂瘤型中耳炎表现为短T1长T2信号（7/11）或等T1长T2信号（4/11），增强后不强化或环形强化。结论 HRCT显示听小骨及乳突骨质结构较佳。对手术及听力恢复有指导意义。MRI则能确定软组织病变性质，可区别肉芽组织和胆脂瘤。

Evaluation of HRCT and MRI in the Diagnosis of Chronic Otitis Media

Objective To evaluate HRCT and MRI in diagnosing chronic otitis media.Materials and Methods HRCT and MRI findings in 72 patients with pathologically proved chronic otitis media were retrospectively analyzed. A comparison between HRCT and MRI was made.Results On HRCT, destroyed and displaced ossicular chain (33/61), bone destruction of mastoid (33/61), disappearance of mastoid air cells (54/61), thickened mucosa in tympanic sinus and cavity with hydrotympanum (55/61), and disrupted sigmoid sinus plate and tegmen tympani with semicircular canal fistula (4/61) were found. Abnormal soft tissue shadow within tympanic cavity or external auditory canal could also be demonstrated on HRCT. MRI could not display petrous bone structure in detail. Chronic exudative otitis media showed long T 1 and long T 2 signals (10/10). Granulomatous otitis media displayed equal T 1 and long T 2 (4/6) or short T 1 and long T 2 (2/6) signals with marked enhancement after injection of Gd DTPA. Cholesteatomatous otitis media carried short T 1 and long T 2 (7/11) or equal T 1 and long T 2 (4/11) signals with no enhancement or ring like enhancement after contrast injection.Conclusion HRCT is of value in displaying ossicular chain and mastoid structures, which is useful in guiding surgical management and hearing recovery. MRI is helpful in identifying the pathological nature of the soft tissue lesion and in distinguishing granulation tissue with cholesteatoma.