Study Finds MRI More Sensitive than CT in Diagnosing Most Common Form of Acute Stroke
A study showed non-contrast MRI is about five times more sensitive than and twice as accurate as immediate non-contrast CT for diagnosing ischemic stroke.
Schmalfeldt: Which imaging technique does a better job at diagnosing an acute stroke — CT or MRI? That's the question researchers at the National Institute of Neurological Disorders and Stroke sought to answer when they compared the two technologies side to side. And when it came to giving a more sensitive diagnosis for acute ischemic stroke — the kind of stroke caused by a blocked blood vessel — the winner was. the MRI. The study showed non-contrast MRI is about five times more sensitive than and twice as accurate as immediate non-contrast CT for diagnosing ischemic stroke. Here's Dr. Steven Warach, director of the NINDS Stroke Diagnostics and Therapeutic Section — senior investigator of the study.
Warach: What our study did is really look at the real world experience. We took a consecutive series of patients — a large number, 356, who came to the hospital emergency room with a diagnosis of possible stroke. This is how it happens in the real world. You don't know before the patient comes to the emergency department whether they really have had it or not. The first encounter is not with a stroke specialist, but with an emergency physician. And at most hospitals, there is not a stroke center or a stroke team, so you have non-specialists all the way up and down looking at the patient. So then we said, if we do the same scans on everybody — non-contrast CT and diffusion-weighted MRI — and then have four independent experts review, which scan will reveal the stroke, and in what proportions will the scans reveal the stroke?
Schmalfeldt: Study leaders hope that because of its increased diagnostic accuracy, MRI may lead to better patient outcomes and ultimately decrease the cost of stroke care, through increased use of acute treatments and earlier initiation of secondary prevention.
Warach: That won't happen overnight, but I do anticipate that over time this will replace CT as the routine screen for questioned stroke. One reason it won't happen overnight is most hospitals are geared up to do the emergency CT and even hospitals that have the MRI — their radiology department schedule and all that — they've not historically made that available. And so it's going to have to take some change in hospital policies and hospital routines for that to happen.
Schmalfeldt: The findings appear in the January 27, 2007 edition of The Lancet. From the National Institutes of Health, I'm Bill Schmalfeldt in Bethesda, Maryland.
About This Audio Report
Reporter: Bill Schmalfeldt
Sound Bite: Dr. Steven Warach
Topic: Medical Imaging