Can 5-mm Axial CT Images Sufficiently Depict the Hyperdense Middle Cerebral Artery Sign in Patients with Acute Brain Ischemia?

The purpose of this study was to determine whether 5-mm axial CT images can sufficiently depict the hyperdense middle cerebral artery (MCA) sign in patients with acute brain ischemia. Materials and Methods: A retrospective review of 92 cases of ischemic brain infarction confirmed nine patients showing hyperdense MCA signs. CT images were acquired on a 64-slice helical scanner. Images were reconstructed into contiguous 5-mm axial, coronal and sagittal datasets. The first CT scan images of the patients with hyperdense MCA signs and an equal number of CT scans without hyperdense MCA signs inserted at random were analyzed in a blinded review. The presence of the hyperdense MCA sign in M1 segments was recorded. Round regions of interest (ROI) were placed over the M1 segments of the MCAs and the attenuation values in Hounsfield units (HU) were measured on the sagittal and axial images. Results: Nine patients showed a hyperdense MCA sign. They consisted of 4 male and 5 female (mean age, 74.3 years; age range, 45 88 years). On the blinded review, hyperdense MCA signs were detected on axial images in 7 patients. In four of the 7 patients, the hyperdense MCA sign was more conspicuous on sagittal images than that on axial images. Hyperdense MCA sign was detected on sagittal images of all 9 patients and exclusive to the sagittal images in two patients. The ROI study showed higher attenuation for the affected MCA on sagittal images (46 65 HU) than that on axial images (36 54 HU). Conclusion: In patients with acute brain ischemia, 5-mm axial CT images cannot sufficiently depict the hyperdense MCA sign. Sagittal images may be superior to axial images for identifying the sign.