Correlation of iodine uptake and perfusion parameters between dual-energy CT imaging and first-pass dual-input perfusion CT in lung cancer

To investigate the potential relationship between perfusion parameters from first-pass dual-input perfusion computed tomography (DI-PCT) and iodine uptake levels estimated from dual-energy CT (DE-CT). The pre-experimental part of this study included a dynamic DE-CT protocol in 15 patients to evaluate peak arterial enhancement of lung cancer based on time-attenuation curves, and the scan time of DE-CT was determined. In the prospective part of the study, 28 lung cancer patients underwent whole-volume perfusion CT and single-source DE-CT using 320-row CT. Pulmonary flow (PF, mL/min/100 mL), aortic flow (AF, mL/min/100mL), and a perfusion index (PI= PF/[PF+AF]) were automatically generated by in-house commercial software using the dual-input maximum slope method for DI-PCT. For the dual-energy CT data, iodine uptake was estimated by the difference (lambda) and the slope (lambda HU). l was defined as the difference of CT values between 40 and 70KeV monochromatic images in lung lesions. lambda HU was calculated by the following equation: lambda HU= vertical bar lambda/(70 +/- 40)vertical bar . The DI-PCT and DE-CT parameters were analyzed by Pearson/Spearman correlation analysis, respectively. All subjects were pathologically proved as lung cancer patients (including 16 squamous cell carcinoma, 8 adenocarcinoma, and 4 small cell lung cancer) by surgery or CT-guided biopsy. Interobserver reproducibility in DI-PCT (PF, AF, PI) and DE-CT (l, lHU) were relatively good to excellent (intraclass correlation coefficient [ICC](Inter)=0.8726-0.9255, ICCInter=0.8179-0.8842; ICCInter= 0.8881-0.9177, ICCInter= 0.9820-0.9970, ICCInter= 0.9780-0.9971, respectively). Correlation coefficient between l and AF, and PF were as follows: 0.589 (P<. 01) and 0.383 (P<. 05). Correlation coefficient between lambda HU and AF, and PF were as follows: 0.564 (P<. 01) and 0.388 (P<. 05). Both the single-source DE-CT and dual-input CT perfusion analysis method can be applied to assess blood supply of lung cancer patients. Preliminary results demonstrated that the iodine uptake relevant parameters derived from DE-CT significantly correlated with perfusion parameters derived from DI-PCT.