HRCT多平面重组及最大密度投影对慢性化脓性中耳炎听骨链病变的术前评估

目的：通过HRCT多平面重组及最大密度投影观察正常听骨链的形态，并对慢性化脓性中耳炎听骨链病变进行术前评估。方法：对20例(40耳）突发性聋患者（对照组）和62例（71耳）慢性化脓性中耳炎患者（病变组）行高分辨率CT 扫描,分别沿三个听小骨的长轴进行多平面重组（MPR），对显示图像直接进行最大密度投影重建（MIP）。对照组比较MPR 和MIP图像整体显示听骨的形态和结构情况；病变组观察听骨链破坏情况，并与手术结果比较。结果：对照组听小骨在MPR及MIP图像均明确显示，MPR对镫骨整体的显示优于MIP， MIP可以立体显示听骨链的空间结构；病变组，胆脂瘤型39例（44耳），MPR显示43耳有听骨破坏，MIP显示41耳有听骨破坏；肉芽肿型15例（17耳），MPR显示6耳有听骨破坏，MIP显示5耳有听骨破坏。单纯性中耳炎8例（10耳），MPR及 MIP均未显示听骨破坏。术中见胆脂瘤型中耳炎41耳有听骨破坏；肉芽肿型中耳炎6耳有骨质破坏，单纯型无听骨破坏。结论: MPR对镫骨的整体显示优于MIP，MIP对听骨链破坏的显示能力优于MPR，两者相结合可以提高听骨链破坏的诊断率，为手术方式的制定提供重要信息。

Evaluation destruction of ossicular chain in chronic otitismedia with MPR and MIP in HRCT

Objective: To observe the ossicular chain structure with multiplanar reconstruction(MPR) and maximum intensity projection(MIP) and evaluate role of MPR and MIP in the destruction of ossicular chain in chronic otitis media(COM).Methods:High-resolution CT scaning was performed in 20 patients(40 ears)with(sudden) deafness(control group)and 62 patients(71 ears)with chronic otitis media(COM group) and the(original)(data) processed with MPR and MIP.The ossicular chain structure in the images generated by these techniques was respectively observed and compared the result with the findings in the operation in the two groups.Results: In the control group,the ossicular chain structure was displayed in both MPR and MIP imaging,while MPR was superior to MIP on the structure of entire stape,and MIP was superior to MPR on the three dimentional structure of ossicular chain.In COM group,the destruction of ossicular chain was displayed by MPR and MIP respectively in 43 and 41 among the patients with cholesteatoma(44 ears),in 6 and 5 among the patients with granuloma(17 ears),and none among the patients with simple COM(10 ears);and it was displayed respectively in 41,6and 0 ear.Conclusion: Using MPR combined with MIP is helpful in the diagnosis and operation on the destruction of ossicular chain.