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Focal Liver Lesion Detection and Characterization with Diffusion-weighted MR Imaging: Comparison with Standard Breath-hold T2-weighted Imaging¹

¹ From the Department of Radiology, New York University Medical Center, 530 First Ave, MRI, New York, NY 10016. Received March 6, 2007; revision requested May 14; revision received June 21; accepted July 19; final version accepted September 17. Partially funded by an award received by T.P. from the Society of Body CT and MRI in 2006. Address correspondence to B.T. (e-mail: bachir.taouli{at}med.nyu.edu).

Purpose: To retrospectively compare diffusion-weighted (DW) magnetic resonance (MR) imaging with standard breath-hold T2-weighted MR imaging for focal liver lesion (FLL) detection and characterization, by using consensus evaluation and other findings as the reference standard.

Materials and Methods: Approval for this retrospective HIPAA-compliant study was obtained from the institutional review board; informed consent was waived. Fifty-three consecutive patients (30 men, 23 women; mean age, 60.7 years) with at least one FLL of 1 cm or greater in diameter were evaluated. Two independent observers reviewed DW (b values of 0, 50, and 500 sec/mm²) and T2-weighted images for FLL detection and characterization. Reference standard for diagnosis was obtained from consensus review by the two observers of DW, T2-weighted, and dynamic contrast material–enhanced images, pathologic data, and follow-up imaging results. Apparent diffusion coefficient (ADC) was measured for FLLs identified at consensus review. DW and T2-weighted images were compared for FLL detection and characterization by using a binary logistic regression model. Receiver operating characteristic curve analyses were conducted to evaluate the utility of ADC for diagnosis of malignancy.

Results: Two hundred eleven FLLs (136 malignant, 75 benign) were detected at consensus review. Overall detection rate (averaged for two observers) was significantly higher for DW (87.7%) versus T2-weighted (70.1%) imaging (P < .001). FLL characterization was not significantly different between DW (89.1%) and T2-weighted (86.8%) imaging (P = .51). ADCs of malignant FLLs were significantly lower than those of benign FLLs (P < .001). The area under the curve for diagnosis of malignancy was 0.839, with sensitivity of 74.2%, specificity of 77.3%, positive predictive value of 85.5%, negative predictive value of 62.3%, and accuracy of 75.3%, by using a threshold ADC of less than 1.60 x 10^–3 mm²/sec.

Conclusion: DW MR imaging was better than standard breath-hold T2-weighted imaging for FLL detection and was equal to breath-hold T2-weighted imaging for FLL characterization.

Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2463070432/DC1

© RSNA, 2008