Evaluation of the susceptibility effect on gradient echo phase images in vivo: a sequential study of intracerebral hematoma.

Susceptibility effect of intracerebral hematoma was estimated on the phase images of gradient echo (GrE). Thirty-five hematomas were studied 3 hr to 5 yr after the onset, a total of 72 times with use of phase and magnitude images of GrE, as well as T1-, T2-, and density-weighted spin-echo (SE) images at 1.5 T. On the basis of the theory of electromagnetism, phase shift to hematoma was calculated for simplified models with concentric distribution of paramagnetic susceptibility. All hematomas were well visualized by the phase images, the pattern of which changed sequentially. The distribution of paramagnetic susceptibility could be estimated by correlating the observed phase shifts with the calculated one. SE images were necessary to presume the type of magnetic substances. A probable hypothesis of the evolution of intracerebral hematoma is proposed.