Abstract:
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.