Multiparametric PET/CT-perfusion does not add significant additional information for initial staging in lung cancer compared with standard PET/CT

Background: The purpose of this study was to assess the relationship of CT-perfusion (CTP), F-18-FDG-PET/CT and histological parameters, and the possible added value of CTP to FDG-PET/CT in the initial staging of lung cancer. Methods: Fifty- four consecutive patients (median age 65 years, 15 females, 39 males) with suspected lung cancer were evaluated prospectively by CT-perfusion scan and F-18-FDG-PET/CT scan. Overall, 46 tumors were identified. CTP parameters blood flow (BF), blood volume (BV), and mean transit time (MTT) of the tumor tissue were calculated. Intratumoral microvessel density (MVD) was assessed quantitatively. Differences in CTP parameters concerning tumor type, location, PET positivity of lymph nodes, TNM status, and UICC stage were analyzed. Spearman correlation analyses between CTP and F-18-FDG-PET/CT parameters (SUVmax, SUVmean, PETvol, and TLG), MVD, tumor size, and tumor stage were performed. Results: The mean BF (mL/100 mL min(-1)), BV (mL/100 mL), and MTT (s) was 35.5, 8.4, and 14.2, respectively. The BF and BV were lower in tumors with PET-positive lymph nodes (p = 0.02). However, the CTP values were not significantly different among the N stages. The CTP values were not different, depending on tumor size and location. No significant correlation was found between CTP parameters and MVD. Conclusions: Overall, the CTP information showed only little additional information for the initial staging compared with standard FDG-PET/CT. Low perfusion in lung tumors might possibly be associated with metabolically active regional lymph nodes. Apart from that, both CTP and F-18-FDG-PET/CT parameter sets may reflect different pathophysiological mechanisms in lung cancer.