Hemorrhage detected using MR imaging in the setting of acute stroke: An invivo model

BACKGROUND AND PURPOSE: The treatment algorithm for acute cerebrovascular a ccidents has traditionally sorted these accidents as either hemorrhagic or nonhemorrhagic, and MR imaging, with its ability to allow expeditious asses sment of vascular substrates and regional blood volume, is well suited for this purpose, Our purpose was to delineate the accuracy of MR imaging in ac ute, hemorrhagic forms of stroke during the time frame considered beneficia l for intervention in an animal model, METHODS: Eighteen dogs with small, iatrogenic parenchymal, subarachnoid hem orrhage (SAH), or both were serially scanned over the initial 6-hour postic tal period, Confirmatory pathologic specimens and 3-hour postictal CT scans were obtained in all animals, The MR and CT studies were then interpreted in a blinded fashion by two neuroradiologists for the presence of hemorrhag e. The results were subjected to receiver operating characteristic analysis . RESULTS: MR imaging depicted acute parenchymal hemorrhage and SAH with a hi gh degree of accuracy at 1.5 T, This finding was independent of each of the time points studied during the 6-hour window. For SAH, the MR accuracy for reader 1 was 0.86 (95% CI, 0.76-0.97); for reader 2, accuracy was 0.85 (95 % CI, 0.71-0.99), The CT accuracy for the two readers was 0.42 (95% CI, 0.2 6-0.58) and 0.66 95% CI, 0.43-0.89, respectively. Fluid-attenuated inversio n-recovery images improved the conspicuity of SAH on MR images and, along w ith spin-density-weighted spin-echo sequences, helped to establish the hemo rrhagic nature, For parenchymal hemorrhage, the MR accuracy for reader 1 wa s 0.90 (95% CI, 0.81-0.99); for reader 2, accuracy was 0.93 (95% CI, 0.84-1 .00), With CT, the accuracy of reader 1 was 0.91 (95% CI, 0.85-0.97) wherea s for reader 2 accuracy was 0.76 (95% CI, 0.69-0.83), Parenchymal hemorrhag e detection and diagnosis was best,vith T2*-weighted gradient-echo images. CONCLUSION MR imaging with appropriately selected sequences appears able to provide information regarding the presence (or absence) of hemorrhage in a n acute stroke model requisite to the initiation of treatment.