Detection of intracranial hemorrhage: Comparison between gradient-echo images and b(0) images obtained from diffusion-weighted echo-planar sequences

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging (DWI) is commonly use d as the initial and sole imaging examination for the detection of acute ce rebral infarction, yet it remains controversial whether MR can detect hyper acute (< 24 h) hemorrhage. Hemorrhage is best detected with gradient-echo ( GRE) T2*-weighted sequences, because of their magnetic susceptibility effec ts. DWI uses a spin-echo echo-planar technique (EPI) that is more sensitive than spin-echo T2-weighted imaging to susceptibility effects. Our aim was to determine whether the b(0) image from the DWI-EPI sequence is as sensiti ve as GRE in detecting hemorrhagic lesions on imaging studies performed to identify acute infarction or hemorrhage. METHODS: All MR studies performed for clinically suspected or radiographica lly confirmed acute infarction or hemorrhage from 2/1/98 to 8/15/99 were re trospectively interpreted by one neuroradiologist in a blinded fashion. The sensitivity of hemorrhage detection, conspicuity of lesions, and diagnosti c certainty were compared between the b(0) EPI and GRE sequences. RESULTS: We found 101 acute infarcts, of which 13 were hemorrhagic, as evid enced by the presence of hypointensity within the infarction on the GRE seq uence. This finding served as the reference standard for detection of hemor rhage. Hemorrhage was diagnosed with confidence in only seven cases (54%) o n b(0) images; 22 acute hematomas were hypointense on GRE images whereas 19 were hypointense on b(0) images (86%); 17 chronic hematomas were depicted on GRE images and 12 on b(0) scans (63%). Punctate hemorrhages and linear c ortical staining were detected on 37 GRE studies but on only four b(0) stud ies. Hemorrhage was always more conspicuous on the GRE sequences. CONCLUSION. b(0) images from a DWI sequence failed to detect minimally hemo rrhagic infarctions and small chronic hemorrhages associated with microangi opathy. GRE scans were more sensitive than b(0) images in the detection of these hemorrhages and should be included in emergency brain MR studies for acute infarction, especially when thrombolytic therapy is contemplated.