Addition of Gadolinium Chelates to Heavily T2-Weighted MR Imaging

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Abstract
OBJECTIVE. The purpose of this study was to determine whether the addition of gadolinium-enhanced imaging to heavily T2-weighted MR imaging of the liver is valuable in differentiating hemangiomas from metastases. The T2 relaxation time was also included in our analysis. SUBJECTS AND METHODS. Fifty-one patients with 52 proven liver lesions (24 hemangiomas and 28 metastases) larger than 1 cm underwent MR imaging at 1.5 T with T2-weighted spin-echo (TR/TE, 3000/80, 160) and gadolinium chelate-enhanced dynamic T1-weighted gradient-recalled echo (80/2.6, 80) pulse sequences. Images were reviewed by observers who were unaware of the patients' clinical history; first, only T2-weighted images were reviewed and then T2-weighted plus dynamic images were reviewed together. The T2 relaxation times were calculated for each lesion. Diagnostic accuracy by each method was compared using receiver operating characteristic analysis. RESULTS. Mean T2 relaxation times were 76 ± 26 msec for metastases and 133 ± 25 msec for hemangiomas. The addition of dynamic scanning to the T2-weighted sequence made a statistically significant difference for only one observer (p = 0.03). However, it did not make a statistically significant contribution for either observer when compared with the T2 relaxation time. Although addition of the dynamic images resulted in correct diagnosis of six lesions, three lesions were misdiagnosed after having been correctly characterized on the T2-weighted images alone. CONCLUSION. When optimized T2-weighted images are obtained and the T2 relaxation time is calculated, routine use of gadolinium enhancement for differentiation of hemangiomas from metastases is unnecessary although dynamic scanning is valuable in selected cases.