64层螺旋CT低剂量双相扫描测定肺体积评价慢性阻塞性肺疾病患者肺功能

目的探讨64层CT低剂量双相扫描肺体积测量指标评估慢性阻塞性肺疾病(COPD)患者肺功能的价值。方法选择经临床肺功能检查确诊的36例COPD患者(COPD组)及30名健康体检者(正常对照组),采用64层CT行深吸气末、深呼气末全肺低剂量(50mAs)及常规剂量(100mAs)吸气末扫描,得出每次扫描的容积CT剂量指数(CTDIvol)和剂量长度乘积(DLP),并换算出有效剂量(ED)。以配对样本t检验比较两组间不同扫描剂量及不同呼吸状态下的CT-DIvol、DLP、ED;应用Fisher确切概率法比较CT图像质量。按扫描层数将全肺分为上、中、下3个肺区,应用Pulmo软件测量和计算COPD组与正常对照组的各体积指标:深吸气末体积(Vin)、深呼气末体积(Vex)、体积差(Vin-Vex)、体积比(Vex/Vin)、体积变化百分比(Vin-Vex)/Vin×100%。于CT检查前后3天完成PFT检查,对比研究指标为第1秒用力肺活量(FEV1)的实测值与预计值的比值(FEV1%)及FEV1与用力肺活量(FVC)的比值(FEV1/FVC)。结果所有图像均成功用于自动分割技术与数据处理。与正常对照组比较,COPD组除各肺区的Vin及上肺区Vin-Vex外,其余各体积指标差异均有统计学意义(P均<0.05);Vex、Vex/Vin、(Vin-Vex)/Vin×100%均与FEV1%、FEV1/FVC存在相关性(P<0.01)。结论 64层CT低剂量双相扫描肺体积指标可较好评价COPD患者肺功能,临床应用价值较高。

Lung volume measurement with 64-slice spiral CT low-dose two-phase scanning for assessing pulmonary function of chronic obstructive pulmonary disease

Objective To explore value of 64-slice spiral CT low-dose two-phase scanning for lung volume indexes in assessing pulmonary function of patients with chronic obstructive pulmonary disease (COPD). Methods Totally 36 COPD patients (COPD group) and 30 healthy people (control group) underwent low-dose (50 mAs) scanning at full inspiration, full expiration and routine-dose (100 mAs) scanning at inspiration. CT dose index (CTDI_vol) and dose length product (DLP) were automatically calculated, and effective dose (ED) was converted. The indexes were compared between the two groups. The lung field was divided into 3 regions by scanning layers. Volume indexes were measured and calculated, including full inspiration (V_in) and full expiration (V_ex), volume difference (V_in-V_ex), volume ratio (V_ex/V_in), volume variation percentage (V_in-V_ex)/V_in×100%. All patients underwent PFT within 3 days of 64-slice CT canning. The contrast research indexes were ratio of true value of forced expiratory volume at the first second (FEV₁) to predictive value (FEV₁%), and ratio of FEV₁ to forced vital capacity (FEV₁/FVC). Results All low-dose images were successfully applied to automatic-dissection and data processing. The differences of indexes at each region and the total lung were statistical significant between the two groups (all P<0.05), except volume difference at upper lung region and volume at full inspiration at each lung region. Correlation was found between V_ex, V_ex/V_in, (V_in-V_ex)/V_in×100% indexes with FEV₁% and FEV₁/FVC. Conclusion 64-slice CT low-dose two-phase scanning volume indexes can be used to evaluate pulmonary function of COPD patients, and its clinical application value is high.