Abstract
BACKGROUND: Inflammatory pseudotumors (IPTs) are often misdiagnosed as malignant solitary pulmonary nodules (SPNs) because their imaging features overlap with those of malignant SPNs, leading to overtreatment. The purpose of this article was to investigate the value of first-pass enhanced time-to-peak (TTP) in distinguishing IPTs from malignant SPNs using dual-input volume computed tomography perfusion (DI-CTP). METHODS: This retrospective study included consecutive patients from No. 82 Group Hospital of Chinese People's Liberation Army with IPTs or malignant SPNs by surgery or biopsy from June 2016 to October 2021. Pulmonary artery flow (PF), bronchial artery flow (BF), perfusion index (PI), time-density curve, total perfusion (TLP), and first-pass TTP for all SPNs were determined by DI-CTP. The receiver operating characteristic (ROC) curve was used to analyse the values of TTP and other perfusion parameters in the differential diagnosis of IPTs and malignant SPNs. RESULTS: Ninety-eight patients were enrolled, including 25 with IPTs and 73 with malignant SPNs. The intraclass correlation coefficient (ICC) for inter-observer and intra-observer reliability of all parameters was perfect (all ICCs >0.90, P<0.01). Compared with IPTs, the malignant SPNs showed significantly higher PF, TLP, and TTP (all P<0.01), without significant differences in BF and PI (all P>0.05). The area under the curve of TTP was 0.987, which was higher than those of the other perfusion parameters (0.987 vs. 0.752 vs. 0.609 vs. 0.728 vs. 0.628). With a cut-off TTP of 18.10 s to distinguish IPNs from malignant SPNs, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 92.0%, 97.3%, 97.3%, 96.0%, and 96.9%, respectively. The sensitivity, specificity, and accuracy of CT plain scan combined with DI-CTP in diagnosing pulmonary nodules were 100%, 96.83%, and 98.97%, respectively. CONCLUSIONS: Compared with other perfusion parameters, TTP may be a more valuable parameter to differentiate IPTs from malignant SPNs.