Distinguishing hemangiomas from metastases on liver MRI performed with gadoxetate disodium: Value of the extended washout sign.

ABSTRACT

OBJECTIVE: To describe the enhancement pattern of hemangiomas with gadoxetate disodium and propose a new sign - the "extended washout sign" - to diagnose hemangiomas on hepatobiliary MR imaging. MATERIALS AND METHODS: In this retrospective IRB approved study, quantitative and qualitative image analysis of 45 hemangiomas and 37 metastases in 77 patients was performed. Gadoxetate disodium-enhanced MR imaging was obtained during arterial and portal venous phases as well as with delays of 3, 8, and 20min. Lesion signal intensity was measured at each phase. Quantitatively, extended washout was defined as a 10% or greater decrease in signal intensity from 8 to 20min on 3D gradient echo images. Statistical analysis was performed using unpaired Student's t-test. Qualitative analysis was also performed to assess observer confidence based on T2-weighted images, dynamic images, and combined early (8min) and late (20min) hepatobiliary phases. Extended washout was defined as a perceptible change in signal from 8 to 20min. RESULTS: On quantitative analysis, 84% of hemangiomas demonstrated a positive extended washout sign while only 18% of metastases did. Qualitatively, 78% of hemangiomas demonstrated a perceptible change in signal from 8 to 20min, while only 5.4% of metastases did. When extended washout was used in combination with T2 hyperintensity, specificity increased to 100%, with a sensitivity of 87% and area under the curve of 0.99. CONCLUSIONS: When combined with T2 signal intensity, the extended washout sign can be used to increase accuracy of differentiating hemangiomas from metastases on gadoxetate disodium-enhanced MRI.