Reproducibility of Dynamic Contrast-Enhanced MRI in Renal Cell Carcinoma: A Prospective Analysis on Intra- and Interobserver and Scan–Rescan Performance of Pharmacokinetic Parameters. Issue 37 (September 2015) - Wang, Haiyi
Abstract : Supplemental Digital Content is available in the text Abstract : Abstract: The objective of this study was to investigate the intra- and interobserver as well as scan–rescan reproducibility of quantitative parameters of renal cell carcinomas (RCCs) with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). A total of 21 patients with clear cell RCCs (17 men, 4 woman; age 37–69 years, mean age 54.6 years, mean size, 5.0 ± 2.2 cm) were prospectively recruited from September 2012 to November 2012. Patients underwent paired DCE-MRI studies on a 3.0 T MR system with an interval of 48 to 72 hours. The extended-Tofts model and population-based arterial input function were used to calculate kinetic parameters. Three observers defined the 2-dimensional whole-tumor region of interest at the slice with the maximum diameter of the RCC. Intraobserver and scan–rescan differences were assessed using paired t tests, whereas interobserver differences using two-way analysis of variance. Intra- and interobserver reproducibility and scan–rescan reproducibility were evaluated using within-subject coefficient of variation (wCoV) and intraclass correlation coefficient (ICC). There were no significant intra-, interobserver, or scan–rescan differences in parameters (all P > 0.05). All ICCs for intra- and interobserver agreements were >0.75 ( P < 0.05), whereas the scan–rescan agreement was moderate to good; V e (0.764, 95% confidence interval [CI]: 0.378–0.925) and K ep (0.906, 95% CI: 0.710–0.972) had higher ICC than K trans (0.686; 95% CI: 0.212–0.898) and V p (0.657; 95% CI: 0.164–0.888). In intra- and interobserver variability analyses, all parameters except V p had low wCoV values. K trans and V e had slightly lower intraobserver wCoV (1.2% and 0.9%) compared with K ep (3.7%), whereas all 3 of these parameters had similar interobserver wCoV values (2.5%, 3.1%, and 2.9%, respectively). Regarding scan–rescan variability, K trans and K ep showed slightly higher variation (15.6% and 15.4%) than V e (10.1%). V p had the largest wCoV in all variability analyses (all >30%). DCE-MRI demonstrated good intra- and interobserver reproducibility and moderate to good scan–rescan performance in the assessment of RCC using K trans, K ep, and V e as parameters under noncontinuous scanning mode. V p showed poor reproducibility, and thus may not be suitable for this scanning protocol.