T2*-weighted MR imaging findings of giant cell tumors of bone: radiological–pathological correlation Abstract Purpose To assess the correlation between T2*-weighted MR imaging and pathological findings of giant cell tumors (GCT) of bone. Methods Of the 33 patients with histopathologically proven GCT of bone, 12 were examined using 1.5-T MR imaging, including T2*-weighted imaging, and were included in this study. The imaging and pathological findings of GCTs were compared between GCTs with and without hypointensity on T2*-weighted images (T2* hypointensity). Results T2* hypointensity was observed in 6 out of 12 (50%) GCTs. Septal formation (83% vs. 17%; p < 0.05) and cystic formation (67% vs. 0%; p < 0.05) on T2-weighted images was significantly more frequent in the GCTs with T2* hypointensity compared with those without T2* hypointensity. Among the six GCTs with T2* hypointensity, a large amount of hemosiderin deposition was pathologically observed in five (83%) cases, whereas small amounts of hemosiderin deposition was seen in one (17%) case. In contrast, among the six GCTs without T2* hypointensity, a small amount of hemosiderin deposition was pathologically observed in all six (100%). Conclusion Half of the GCTs showed T2* hypointensity, which is characteristic of hemosiderin deposition; whereas, the other half did not show T2* hypointensity due to a small amount of hemosiderin deposition.