Fig. 4.

MR imaging of intramuscular hematoma seven days after injury.

A. Axial spin echo T1-weighted image shows slightly increased signal intensity (arrows) and high signal nodule. Value of relative signal intensity is 1.49. B. Axial T2-weighted image shows heterogeneous central high signal intensity and peripheral dark signal rim (central relative signal intensity: 12.2, peripheral relative signal intensity: 0.78). C. Gradient echo image shows central high signal intensity with peripheral dark signal rim (central relative signal intensity: 2.86, peripheral relative signal intensity: 0.33). D, E. Microscopic findings of intramuscular hematoma (arrows) (Hematoxylin & Eosin stain, original magnification in D, × 10; in E × 400) show some hemosiderin-laden macrophages (arrows in E), fibrosis and regenerating muscle bundle fibers. ○= region of interest for measuring relative signal intensity