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目的研究多层CT(MSCT)低剂量扫描图像最大密度投影(MIP)重建对肺小结节的检出情况。方法将8例尘肺患者的尸检离体肺脏制成充气固定肺标本,分别行多层CT常规剂量(100 mA)和低剂量(50、30和10mA)扫描,层厚5min,重建间隔5min,标准算法重建,并做1．25mm薄层无重叠重建,然后以1．25mm薄层图像行8．5mm MIP重建,比较不同剂量重建图像对肺小结节的显示。结果3种低剂量MIP与常规剂量NIP重建图像对8例尘肺标本检出的肺小结节数量分别为217、214、207及223,差异均无统计学意义(P＞0．05)。3种低剂量MIP显示结节的敏感性分别为97．31%、95．96%及92．83%,特异性分别为63．16%、63．16%和47．37%,阳性预测值分别为96．87%、96．83%和95．31%。结论多层CT常规层厚、低剂量扫描,薄层重建后行MIP重建,能理想的显示常规剂量扫描MIP重建所能显示的肺小结节。
Objective To study the detection of pulmonary nodules by MIP reconstruction of low-dose multi-slice CT (MSCT) images. Methods Eight patients with pneumoconiosis were divided into four groups: inflatable fixed lung specimens and routine multi-slice CT (100 mA) and low dose (50, 30 and 10 mA) scans respectively. The layer thickness was 5 min and the interval The algorithm was reconstructed and reconstructed with 1.25mm thin layer without overlapping. Then, a 1.25mm MIP reconstruction was performed with a 1.25mm thin-layer image to compare the display of pulmonary nodules with different dose reconstruction images. Results The number of pulmonary nodules detected in 8 cases of pneumoconiosis was 217, 214, 207 and 223, respectively, with no significant difference between the three low-dose MIP and routine dose NIP reconstruction images (P> 0.05). The sensitivities of the three low dose MIPs were 97.31%, 95.96% and 92.83%, respectively, and the specificity were 63.16%, 63.16% and 47.37%, respectively. The positive predictive value Respectively 96.87%, 96.83% and 95.31%. Conclusions Multi-slice CT conventional thickness, low-dose scanning, thin-layer reconstruction after MIP reconstruction, ideal display of conventional dose scanning MIP reconstruction can show the pulmonary nodules.