特发性肺间质纤维化HRCT病变区与非病变区^18F-FDG PET/CT表现分析

^18F-FDG PET/CT imaging analysis of regions with abnormal and normal pulmonary parenchyma on high resolution CT in idiopathic pulmonary fibrosis patients

目的 对比分析特发性肺间质纤维化（IPF）高分辨率CT（HRCT）上病变区域和非病变区域的PET/CT表现及其诊断价值。方法 按照IPF的临床诊断标准，选取接受PET/CT检查并有完整资料的IPF病例及健康体检者各27例，规定病变区域为HRCT上表现为磨玻璃密度影、网格影及蜂窝影等区域，非病变区域为肉眼可观察到的密度低于病变区的最小密度区，测定病变区域的SUVmax，分别在IPE组非病变区域和对照组肺部HRCT横断面图像上画取ROI，测量其CT值，并在PET/CT图像相应位置画取ROI，测量SUVmax、平均标准化摄取值（SUVmean），计算与纵隔大血管主动脉弓血池（SUVmax、SUVmean）比值：肺组织/纵隔血池最大摄取比（LT/MBmax）和肺组织/纵隔血池平均摄取比（LT/MBmean）。采用独立样本t检验比较组间LT/MBmax、LT/MBmean及CT值差异。结果 IPF组27例患者，其中肺部表现为磨玻璃密度影14例、网格影27例、蜂窝影13例，同一患者可有多种表现，以上表现均为放射性摄取增高，SUVmax值为2.32±1.10。IPF组非病变区域LT/MBmax（0.44±0.55 vs.0.32±0.05）和LT/MBmean（0.55±0.38 vs.0.33±0.05）均高于对照组（t=5.87和2.89，P均〈0.05）；但两组CT值（-836.59±32.33 vs.-837.99±29.90）比较，差异无统计学意义（t=-0.15，P〉0.05）。结论 IPF患者HRCT上显示的病变区与非病变区对18F-FDG摄取均增加，PET/CT在IPF诊断及治疗监测方面有一定优势。

Objective To compare and analyze the PET signals at regions with abnormal and normal pulmonary parenchyma on high resolution CT（HRCT） in idiopathic pulmonary fibrosis（IPF） patients to explore the diagnostic value of PET/CT. Methods According to the standards for the clinical diagnosis of IPF, a total of 27 IPF patients（21 men and 6 women） and 27 control populations（19 men and 8 women） were randomly selected and recruited for PET/CT. The abnormal regions were described to show ground-glass appearance, reticulation, honeycombing, and so on. Normal regions corresponding to areas of minimal observed density were noted as distinct from the abnormal regions. The maximal standard uptake value（SUVmax） of the abnormal regions was measured. The ROI in HRCT images of the control population was placed in areas of each lung that were considered morphologically normal to measure the CT densities. The ROI was selected in PET/CT images at corresponding locations; the SUVmax and mean standard uptake value（SUVmean） were measured and used to calculate the aortic blood pool of mediastinal large blood vessels. The LT/MBmax, LT/MBmean, and CT densities of each ROI were analyzed by the independent sample t-test. Results Increased pulmonary 18F-FDG uptake was observed in 27 of 27 patients. The parenchymal patterns on HRCT at the site of high metabolism were ground-glass appearance（14/27）, reticulation（27/27）, and honeycombing（13/27）. The LT/MBmax in the normal lung parenchyma of IPF patients was higher than in the control population[（0.44±0.55 vs. 0.32±0.05）; t=5.87, P〈0.05]. The LT/MBmean in normal lung parenchyma of IPF was higher than in the controls[（0.55±0.38 vs. 0.33±0.05）; t=2.89, P〈0.05]. The CT densities in normal lung parenchyma of IPF and control population were not significantly different[（-836.59±32.33 vs. -837.99±29.90）; t=-0.15, P〉0.05]. Conclusions IPF patients showed increased pulmonary uptake of 18F-FDG on PET in lung regions with abnormal and normal morphological appearances on HRCT. Therefore, PET/CT gives superior diagnosis and therapeutic monitoring.