Purpose: To determine the diagnostic accuracy of dual-energy CT (DECT) using quantitative iodine concentration in patients with indeterminate renal masses using histopathologic analysis and/or follow-up imaging as the reference standard. The secondary objective is to compare accuracy of iodine concentration to conventional Hounsfield Unit (HU) measurements to quantify enhancement.

Methods: We searched Medline, Embase and CENTRAL for studies evaluating the accuracy of DECT for renal mass characterization between 1947-2018. Inclusion criteria:  studies evaluating quantitative iodine concentrations in human patients with indeterminate renal masses. Risk of bias and applicability were assessed using QUADAS-2. Bivariate random-effects model was used to determine pooled sensitivity and specificity. Variability was assessed by subgroup analyses (DECT technique, risk of bias), and meta-regression (DECT vs conventional CT).

Results: Of 201 studies identified, 5 were included (412 patients). Pooled sensitivity and specificity for DECT were 96.6 (95% CI: 85.9-99.3) and 95.1 (95% CI:90.7-97.5) respectively. Meta-regression evaluating the influence of the test type (DECT vs. conventional CT) did not identify differences in accuracy (P=0.06). In subgroup analyses, no difference in accuracy based on risk of bias, or DECT technique were identified. Limitations include small number of included studies, most of which were at risk of bias.

Conclusion: DECT with iodine quantification shows sensitivity and specificity (>95%) for evaluation of indeterminate renal masses and may be an alternate to conventional CT for assessment of renal masses. Larger scale trials are needed to corroborate our findings.

Dual-energy computed tomography (DECT) for evaluation of indeterminate renal masses: systematic review and meta-analysis