Original Research Hyperintense Nodules on Non-Enhanced T1- Weighted Gradient-Echo Magnetic Resonance Imaging of Cirrhotic Liver: Fate and Clinical Implications Jeong-Sik Yu, MD, * Jei Hee Lee, MD, Mi-Suk Park, MD, and Ki Whang Kim, MD Purpose: To investigate the fate of hyperintense hepatic nodules on nonenhanced T1-weighted (T1w) gradient-echo (GRE) magnetic resonance (MR) images in cirrhotic pa- tients. Materials and Methods: A total of 79 cirrhotic patients with hyperintense nodules (5 mm) on precontrast op- posed-phase (repetition time (TR)/echo time (TE) = 140/ 2.7 msec) GRE images from initial MRI without T2- weighted (T2w) hyperintensity or arterial hypervascularity were subjected to analysis of subsequent MR images ob- tained at intervals of 12–56 months (mean = 24.5 months). Multiplicity of hyperintense nodules (group A, up to 8; group B, 8) was correlated with follow-up changes. Results: Group B patients were younger (P = 0.003) than group A patients (mean = 47.5 and 56.2 years, respec- tively). In 66 group A patients, 39 out of 143 lesions (27%) were enlarged, including 20 malignantly transformed or borderline lesions. Of the 104 lesions (the eight largest lesions in each patient) in 13 group B patients, only three (2.9%) were enlarged. The results of best- and worst-case analyses showed that overall the lesions were benign in 91% and 82% of patients, respectively. Conclusion: T1w hyperintense nodules without T2w hy- perintensity or arterial hypervascularity in the cirrhotic liver are benign in most cases. In younger patients with numerous macronodules, almost all of these lesions follow a benign course. Key Words: liver, cirrhosis; liver, nodules; liver, neo- plasms; liver, neoplasms; MR J. Magn. Reson. Imaging 2006;24:630 – 636. © 2006 Wiley-Liss, Inc. THE GOAL OF IMAGING DIAGNOSIS of the cirrhotic liver is the early detection and characterization of ma- lignant or premalignant lesions from background pa- renchyma consisting of fibrosis and benign cirrhotic nodules. Many investigators have reported that be- cause of its inherently high tissue contrast, magnetic resonance imaging (MRI) is able to differentiate hepato- cellular nodules (1–10). It is now well established that IV contrast-enhanced imaging of the cirrhotic liver also increases the diagnostic yield for hepatocellular carci- nomas (HCCs), with or without liver-specific contrast agent. However, in hepatocellular lesions, such as pre- malignant dysplastic nodules and some small HCCs, the T2-weighted (T2w) signal intensity and/or enhance- ment patterns seen in various contrast-enhanced stud- ies may fail to distinguish the lesions from the cirrhotic background (11–13). Without T2w hyperintensity or arterial phase en- hancement during dynamic imaging, T1-weighted (T1w) hyperintense nodules are diagnostically challeng- ing in daily practice due to their distinguished appear- ance from the cirrhotic background. Some investigators have claimed that T1w hyperintensity on precontrast MRI is a finding that is specific to dysplastic nodules (also termed adenomatous hyperplasia or macroregen- erative nodules) in conjunction with T2w hypointensity (3,14 –17). Some HCCs, including small or well-differ- entiated lesions, also show T1w hyperintensity and iso- or hypointensity on T2w images in explanted liver stud- ies (1,2,9,11). However, in our experience over the past decade, many hyperintense nodules on unenhanced T1w gradient-echo (GRE) imaging do not exhibit any malignant behavior during long-term serial clinical fol- low-ups. The purpose of this study was to investigate the fate of T1w hyperintense nodules in the cirrhotic liver, including the incidence of malignant transforma- tion, and to discuss the associated clinical implica- tions. MATERIALS AND METHODS Patients and MRI Approval for this retrospective study was obtained from our institutional review board, which waived the re- Department of Diagnostic Radiology and the Research Institute of Ra- diological Science, Yonsei University College of Medicine, YongDong Severance Hospital, Seoul, Republic of Korea. *Address reprint requests to: J.S.Y., Department of Radiology, Yonsei University College of Medicine, YongDong Severance Hospital, 146-92 Dogok-Dong, Gangnam-Gu, Seoul 135-720, South Korea. E-mail:yjsrad97@yumc.yonsei.ac.kr Received December 7, 2005; Accepted May 19, 2006. DOI 10.1002/jmri.20674 Published online 3 August 2006 in Wiley InterScience (www.interscience. wiley.com). JOURNAL OF MAGNETIC RESONANCE IMAGING 24:630 – 636 (2006) © 2006 Wiley-Liss, Inc. 630