Intracranial hemorrhagic lesions: evaluation with spin-echo and gradient-refocused MR imaging at 0.5 and 1.5 T.

Twenty patients with intracranial hemorrhage were examined with magnetic resonance (MR) imaging at 0.5 and 1.5 T within 2 hours on the two imagers for lesions less than 30 days old and within 24 hours for lesions older than 30 days. MR studies included T1- and T2-weighted spin-echo (SE) and T2*-weighted gradient-refocused (GR) pulse sequences at each field strength. The number of lesions identified and the characteristics (ie, signal intensity of the margin, body, and core) of each hemorrhagic lesion were assessed and compared by means of the three pulse sequences at each field strength. Lesion depiction and characterization were superior (P less than .01) at 1.5 T with T2-weighted SE sequences. Improved depiction and characterization of lesions 300 or more days old (P less than .01) accounted for this result. With the GR sequence, depiction and characterization were similar at both field strengths. The GR sequence did not provide significant additional information about hemorrhage at 1.5 T in this series, but it improved depiction and characterization of hemorrhage at 0.5 T.