Quantitative parameters of static imaging and fast kinetics imaging in ¹⁸F-FDG total-body PET/CT for the assessment of histological feature of pulmonary lesions

Background: To investigate the value of quantitative parameters related to static imaging and fast kinetics imaging of total-body (TB) 2-[F-18]-fluoro-2-deoxy-D-glucose (F-18-FDG) positron emission tomography/ computed tomography (PET/CT) in differentiating benign from malignant pulmonary lesions and squamous cell carcinoma (SCC) from adenocarcinoma (AC) and to analyze the correlation of each parameter with the Ki-67 index. Methods: A total of 108 patients with pulmonary lesions from July 2021 to May 2022 in the Henan Provincial People's Hospital, China, were consecutively recruited for TB F-18-FDG PET/ CT in this prospective study. Static imaging parameters maximum standardized uptake value (SUVmax) and fast kinetics imaging parameters transport constant (K-1), rate constants (k2), time delay (t(d)), and fractional blood volume (v(b)) were calculated and compared. The area under the receiver operating characteristic (ROC) curve (AUC), Delong test, Logistic regression analyses, and Pearson correlation were used to assess diagnostic efficacy, find independent predictors and analyse correlations respectively. Results: Malignant lesions had higher SUVmax and K-1 and lower v(b) than benign lesions, and SCC had higher SUVmax and K-1 and lower t(d) and v(b) than AC (all P<0.05). For the differentiation of benign and malignant lesions, SUVmax, K-1, and v(b) were independent predictors, and AUC (SUVmax + K-1 + v(b)) =0.909 (95% CI: 0.839-0.956), AUC (SUVmax) =0.883 (95% CI: 0.807-0.937), AUC (K-1) =0.810 (95% CI: 0.723-0.879), and AUC (v(b)) =0.746 (95% CI: 0.653-0.825), where AUC (SUVmax + K-1 + v(b)) was significantly different from AUC (K-1), AUC (v(b)) (Z=3.006, 3.965, all P<0.05). For the differentiation of SCC and AC, SUVmax, K-1, t(d), and v(b) were independent predictors, and AUC (SUVmax + K-1 + t(d) + v(b)) =0.946 (95% CI: 0.840-0.991), AUC (SUVmax) =0.818 (95% CI: 0.680-0.914), AUC (K-1) =0.770 (95% CI: 0.626-0.879), AUC (v(b)) =0.737 (95% CI: 0.5900.853), and AUC (t(d)) =0.669 (95% CI: 0.510-0.791), where AUC (SUVmax + K-1 + t(d) + v(b)) was significantly different from AUC (SUVmax), AUC (K-1), AUC (v(b)), and AUC (t(d)) (Z=2.269, 2.821, 2.848, and 3.276, all P<0.05). SUVmax and K-1 were moderately and mildly positively correlated with the Ki-67 index (r=0.541, 0.452, all P<0.05), respectively. Conclusions: Quantitative parameters of static imaging and fast kinetics imaging in F-18-FDG total-body PET/CT can be used to differentiate benign from malignant pulmonary lesions and SCC from AC and to assess Ki-67 expression.