Can quantitative iodine parameters on DECT replace perfusion CT parameters in colorectal cancers?

Objectives To determine the correlation between iodine concentrations derived from dual-energy CT (DECT) and perfusion CT (PCT) parameters in patients with pathologically proven colorectal cancers (CRC) and to evaluate their reproducibility and respective radiation exposures. Methods Institutional review board approval and written informed consents were obtained for this study. Forty-one patients with CRCs who underwent same-day DECT and PCT were prospectively enrolled. Three radiologists independently analyzed the iodine concentration of the tumors and iodine ratios [ ratio of lesion to aorta (IRa) or to infrarenal IVC (IRv)] from DECT as well as blood flow (BF), blood volume (BV), permeability (PMB), and mean transit time (MTT) from PCT. Pearson R and linear correlation, paired t-test, and intraclass correlation coefficients (ICCs) were used. Results Significant correlations were found between iodine parameters from DECT and PCT parameters: iodine concentration of tumors and BV (r = 0.32, p = 0.04), PMB (r = 0.34, p = 0.03), and MTT (r = -0.38, p = 0.02); iodine ratio (IRa) and MTT (r = -0.32, p = 0.04); iodine ratio (IRv) and BF (r = 0.32, p = 0.04) and PMB (r = 0.44, p = < 0.01). DECT showed better intra- and interobserver agreements (ICC = 0.98, 0.90 in iodine concentration; 0.98, 0.91 in IRa; and 0.91, 0.93 in IRv, respectively) than PCT (ICC = 0.90, 0.78 in BF; 0.82, 0.76 in BV; 0.75, 0.75 in PMB; 0.64, 0.79 in MTT, respectively). As for radiation dosage, CTDIvol and DLP in DECT (10.48 +/- 1.84 mGy and 519.7 +/- 116.7 mGy.cm) were significantly lower than those of PCT (75.76 mGy and 911 mGy.cm) (p < 0.01). Conclusion Iodine parameters from DECT are significantly correlated with PCT parameters, but have higher intra- and interobserver agreements and lower radiation exposure.