Computed Tomography (CT) is the mainstays modality of neuroimaging. An X-ray tube within a circular gantry revolves around the patient, and radiation detectors on the opposite side of the gantry detect the X-ray beam and send the information to sophisticated computers that generate a series of cross-sectional images. It is now readily available in most centres and is an excellent initial examination for brain abnormalities.
Hyperdense MCA sign on Non Contrast CT Head
Perfusion Imaging is an Advanced Stroke Imaging Modality, that is used as an additional tool for assessment of ischemic pneumbra, ie. tissue at risk. It is also useful in detection of distal occlusions.
Matched Perfusion Deficit, ie. all areas of increased contrast transit time correspond to low CBV values and hence represent infarcted tissue. There is no brain to save here.