Thioguanin-induced nodular regenerative hyperplasia of the liver-ROC analysis of different MR techniques

The aim of this study was to evaluate the diagnostic value of different magnetic resonance (MR) techniques for the diagnosis of nodular regenerative hyperplasia (NRH). Thirty-one patients with inflammatory bowel disease, who received 6-thioguanin, underwent liver biopsy and liver MRI on a 1.5-T MR system, with gadolinium and superparamagnetic iron oxide particles (SPIO). MR imaging (MRI) was evaluated independently as well as in consensus by two blinded readers, who received the following image sets: pre-contrast; pre-contrast and gadolinium-enhanced; pre-contrast and SPIO-enhanced and all images. The results were correlated with histopathology and diagnostic efficacy parameters were calculated. NRH was found in 13/31 patients. The set "all images" showed the highest sensitivity (84.6%), accuracy (77.4%) and negative predictive value (86.7%). However, results for gadolinium were only slightly inferior. The highest specificity (76.5%) was found for SPIO. The A(z) values of both readers were highest for gadolinium (mean A(z) = 0.824). It can be concluded that gadolinium-enhanced and SPIO-enhanced MRI enable an accurate diagnosis of NRH. Since gadolinium-enhanced MRI is very sensitive, it should be used for screening high-risk patients. SPIO-enhanced MRI is less sensitive, but more specific. The combination of both guarantees a high sensitivity and specificity and, therefore, is the diagnostic procedure of choice.