Evaluation of dual-energy and perfusion CT parameters for diagnosing solitary pulmonary nodules

Background To evaluate the correlation and accuracy of dual-energy CT (DECT) (70/Sn150) and low-dose volume perfusion CT (VPCT) parameters for the diagnosis of solitary pulmonary nodules (SPN). Methods A total of 15 patients with benign SPN (mean age 56 +/- 7 years) and 34 patients with malignant SPN and clinical indication for surgery (mean age 58 +/- 6 years) were enrolled from July 2017 to September 2019 at a single institution. All the patients underwent low-dose VPCT with a scan volume of 114 mm on the z-axis and a venous phase enhancement DECT (70/150 Sn) scan just before surgery on the same day. All CT findings were studied in comparison with the pathological results after surgery. Perfusion and dual-energy CT parameters such as blood flow (BF), blood volume (BV), mean transit time (MTT), flow extraction product (FED), pulmonary nodule enhancement peak (PPnod) and iodine concentration (IC) were evaluated as well as t-test, chi-square test, Pearson correlation analysis, and ROC curve analysis to determine the significance of study parameters. Results The effective radiation dosage of the VPCT and DECT scans were 4.67 +/- 0.26 mSv and 0.32 +/- 0.10 mSv, respectively. Significant correlations were found between iodine concentration from DECT and VPCT parameters (r = 0.376-0.533, p < 0.05). The sensitivity and specificity of IC to differentiate the SPN were 86.67% and 72.73%, which was slightly lower than that of BV (94.44%, 73.33%), FED (88.89%, 80.00%) and PPnod (94.44%, 80.00%). Conclusions VPCT scans have low radiation dosage achieved by shortening the z-axis scan range for assessment of SPN. IC from DECT is significantly correlated with VPCT parameters, and VPCT parameters have better diagnostic performance for SPN than DECT parameters.