Detection of liver metastases using gadoxetic-enhanced dynamic and 10- and 20-minute delayed phase MR imaging.

Purpose: To assess the incremental value of hepatobiliary phase images in gadoxetate disodium-enhanced magnetic resonance imaging (MRI), and to compare diagnostic accuracy and lesion conspicuity on 10- and 20-minute delayed images for preoperative detection of hepatic metastases with subgroup analysis according to size and history of chemotherapy. Materials and Methods: Forty-six patients with 107 metastases who underwent surgery after gadoxetate disodium-enhanced MRI were evaluated. Four observers independently interpreted three sets: dynamic set comprising precontrast T1-, T2-weighted, and dynamic images; 10-minute set comprising dynamic set and 10-minute delayed; 20-minute set comprising 10-minute set and 20-minute delayed. Diagnostic accuracy was compared with subgroup analysis. Liver-to-lesion signal ratio (SR) was calculated using the region of interest method and compared. Results: Mean A_z and sensitivities were significantly higher for 10- ( A_z = 0.894, sensitivity = 95.6%) and 20-minute (0.910, 97.2%) than dynamic set (0.813, 79.9%) ( P < 0.001), with no significant difference between 10- and 20-minute sets ( P = 0.140). In patients with small (≤1 cm) metastases and a history of chemotherapy, sensitivities were significantly higher with 10- (88.2%) and 20-minute (91.6%) sets than dynamic set (48.6%) ( P < 0.001). SR was significantly higher for 10- and 20-minute delayed than precontrast and dynamic, with significantly higher SR on 20- than 10-minute delayed. Conclusion: Regardless of size or prior chemotherapy, detection of hepatic metastases was significantly improved by adding hepatobiliary phase images without significant differences between 10- and 20-minute delayed. J. Magn. Reson. Imaging 2012;35:635-643. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]