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Acute ischemic stroke occurs when blood vessels to the brain is blocked by a clot.  MRI is the standard test done to diagnose acute ischemic stroke as it is more sensitive and accurate than a conventional CT. But with the advent of CT assisted dynamic perfusion imaging (perfusion CT, PCT), acute ischemic stroke can be diagnosed quickly and with precision, according to a new study.

Standard MRI uses computer-generated radio waves and a powerful magnet to produce detailed slices or three-dimensional images of body structures and nerves. In PCT a short intravenous contrast medium bolus is given during which one slice, or with a Multi Slice CT scanner, several CT slices, can be acquired repeatedly at fixed time intervals. Usually, for instance, 40 ml of contrast medium are administered with a scanning period of 45 seconds and an imaging frequency of 1 image/second.

The benefits of PCT were proven by a large single-centre study conducted by Dr. Rai and his team, from the department of radiology, West Virginia University Health Sciences Centre in Morgantown. They reviewed over 400 patients and found CT perfusion scans to be very accurate and rapid, and the procedure would take just five minutes while an MRI would take about half an hour. The sensitivity of the procedure was 92.2% while the specificity was 100%, quoted the authors in the October issue of the Journal of Emergency Medicine.

"Our study reveals that the widespread use of CT perfusion is a practical way to help busy emergency departments save precious time in stroke diagnosis, target treatment and reduce the risks of inappropriate thrombolytic use," Dr. Rai added in a university statement.