Distinguishing enhancing from nonenhancing renal masses with dual-source dual-energy CT: iodine quantification versus standard enhancement measurements.

Abstract Purpose To compare the diagnostic accuracy of iodine quantification and standard enhancement measurements in distinguishing enhancing from nonenhancing renal masses. Materials and methods The Institutional Review Board approved this retrospective study conducted from data found in institutional patient databases and archives. Seventy-two renal masses were characterised as enhancing or nonenhancing using standard enhancement measurements (in HU) and iodine quantification (in mg/ml). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of standard enhancement measurements and iodine quantification were calculated from χ2 tests of contingency with histopathology or imaging follow-up as the reference standard. Difference in accuracy was assessed by means of McNemar analysis. Results Sensitivity, specificity, PPV, NPV and diagnostic accuracy for standard enhancement measurements and iodine quantification were 77.7 %, 100 %, 100 %, 81.8 %, 89 % and 100 %, 94.4 %, 94.7, 100 % and 97 %, respectively. The McNemar analysis showed that the accuracy of iodine quantification was significantly better (P<0.001) than that of standard enhancement measurements.Conclusion Compared with standard enhancement measurements, whole-tumour iodine quantification is more accurate in distinguishing enhancing from nonenhancing renal masses. Key Points • Enhancement of renal lesions is important when differentiating benign from malignant tumours. • Dual-energy CT offers measurement of iodine uptake rather than mere enhancement values. • Whole-tumour iodine quantification seems more accurate than standard CT enhancement measurements.