MSCT胸部低剂量扫描对慢性肺部病变的应用研究

Low Dose MSCT for Diffuse or Chronic Infietative Lung Disease

目的:比较低剂量及常规剂量扫描对慢性肺部弥漫性病变(范围较广泛者)的显示差异,探讨低剂量扫描诊 断慢性弥漫性或浸润性肺部病变的可行性及合理扫描方案。方法:34例慢性肺部病变患者及4例临床怀疑支气管扩张但 CT扫描未见异常的患者,行低剂量(50mAs)全肺螺旋扫描,14例患者并行常规剂量(195mAs)全肺增强扫描,所有病例 在病变部位加低剂量(50mAs)及常规剂量(220mAs)薄层(2.5mm)HRCT扫描。比较低剂量及常规剂量扫描对病变范 围、分布及病变特征的显示差异。结果:两种剂量全肺扫描(重建层厚7.5mm)图像对肺部病变分布的范围及各种征象的 显示差异无显著性意义(P>0.05);两种剂量的薄层HRCT图像对各种病变征象均可以显示,但是对支气管扩张、蜂窝样 改变、纤维索条及胸膜下线的显示以常规剂量为优(P<0.05),对其它征象的显示两组剂量差异无显著性意义(P> 0.05)。结论:对于怀疑肺弥漫性病变的患者,可以采用低剂量全肺扫描,病变部位加常规剂量薄层HRCT扫描。

Objective:To compare the low dose and conventional dose scan with MSCT for displaying chronic diffuse or infiltrative lesions of the lung and to study the feasibility and the appropriate scan protocols.Methods:Low dose (50mAs) MSCT scan was performed in 38 patients suspected of having diffuse or infiltrative lung disease with a collimation of 2.5mm and a pitch of 1.25.Low dose (50mAs) and conventional dose (220mAs) high resolution CT scan were performed at levels with typical lesions.The source images with lose dose and coventional dose CT scan of the whole lung in 14 patients were reconstructed into images of 7.5mm slice thickness with standard algorithm.CT images acquired with low and conventional dose protocols were compared with respect to distribution pattern and characteristics of the lesions.Result:No significant difference between CT images acquired with low and conventional dose protocols with a section thickness of 7.5mm in displaying the distribution,extent and various signs of the lesions of the lung.Conventional dose thin-slice MSCT was superior to low dose thin-slice MSCT in demonstrating signs such as bronchiectasis,honeycomb,fibrotic linear change and subpleural lines.Conclusions:Low-dose CT is feasible in demonstrating signs of diffuse lung diseases with conventional slice thickness.When high resolution thin slice CT is needed for the region of interest,conventional dose CT is preferable to low dose thin slice CT.