MR DIAGNOSIS OF SUBACUTE AND CHRONIC SUBARACHNOID HEMORRHAGE - COMPARISON WITH CT

OBJECTIVE. The purpose of our study was to compare the value of MR ima ging with CT in the diagnosis of subarachnoid hemorrhage in the subacu te and chronic stages (>3 days after the hemorrhagic episode). MATERIA LS AND METHODS. We performed 42 MR examinations using a 0.5-T unit in 37 patients with subarachnoid hemorrhage caused by a ruptured aneurysm . Examinations were done 4-75 days after the ictus. We obtained 40 T1- weighted, 11 proton density-weighted, 15 T2-weighted, and 28 moderatel y T2-weighted images. CT was also performed in all patients within 24 hr of the MR examination. Confirmation of the presence of subarachnoid hemorrhage at the time of the MR examination was made by CSF examinat ion using lumbar puncture or surgical findings. RESULTS. In the subacu te and chronic stages, subarachnoid hemorrhage was seen as an area of high signal intensity on T1-weighted, proton density-weighted, T2-weig hted, and moderately T2-weighted MR images in 63%, 90%, 25%, and 92% o f cases, respectively. On CT scans, subarachnoid hemorrhage was seen a s an area of high attenuation in only 46% of cases. Especially in the chronic stage, subarachnoid hemorrhage was seen as an area of high sig nal intensity more frequently by MR imaging than by CT (90% on T1-weig hted images; 100% on proton density-weighted images; 25% on T2-weighte d images; 100% on moderately T2-weighted images; and 10% on CT scans). High-signal-intensity subarachnoid hemorrhage was demonstrated by MR imaging until a maximum of 39 days after the ictus, whereas high-atten uation subarachnoid hemorrhage was demonstrated by CT until a maximum of 17 days after the ictus. CONCLUSIONS. Our findings show that MR ima ging is superior to CT for the diagnosis of subacute and chronic subar achnoid hemorrhage, MR imaging is especially useful for the diagnosis of chronic subarachnoid hemorrhage.