MRI for Stroke Screening Feasible

Pauline Anderson

May 26, 2015

Researchers have demonstrated the feasibility of using MRI instead of the standard computed tomography (CT) to screen stroke patients for eligibility to receive tissue plasminogen activator (tPA).

The study, which focused on quality improvement processes, not only showed a significant 40% reduction in median door to needle (DTN) time with MRI but also a four-fold increase in the proportion of patients treated with tPA in under an hour.

Faster onset of treatment of intravenous (IV) tPA in acute ischemic stroke has been shown to improve neurologic outcomes.

The results have important implications for the future cost-effective use of MRI for stroke patients in both large and suburban hospitals, said study author Amie W. Hsia, medical director, Comprehensive Stroke Center MedStar Washington Hospital Center, Washington, DC.

Dr Amie W. Hsia

The study was published online May 13 in Neurology.

Biggest Opportunity

For this analysis, the researchers investigated stroke treatment processes at two hospitals: MedStar, a 900-bed tertiary care facility with 1000 stroke admissions per year, and the Suburban Hospital, a 230-bed community hospital in Bethesda, Maryland, that has 400 stroke admissions annually. In both hospitals, the MRI suite is located on the same floor as the emergency department (ED), within about 150 feet.

Beginning with the second quarter of 2013, both hospitals implemented quality improvement processes. These included interventions to expedite intravenous tPA treatment with the participation of ED physicians, nurses and technicians, radiology and laboratory staff, and acute stroke teach staff.

Researchers determined that the "biggest opportunity" to cut time was after patients arrive in the ED and before the MRI scan, said Dr Hsia. "There are so many activities that have to take place before the scan can even start."

She and her colleagues "went through extraordinary detail" in determining where redundancies lay and what processes could be streamlined, according to Dr Hsia. They noted, for example, that some team members "were doing double and triple the same task," while others were unclear about who was responsible for a particular task, she said.

As well, instead of continuing to use the same standard MRI screening form that is typically used in a nonemergency setting, the team whittled it down to a few basic questions. "We completely simplified it," said Dr Hsia.

Between January 2012 and December 2013, 1066 patients were screened and diagnosed on admission with an acute ischemic stroke at both hospitals combined. Of these, 157 (15%) received IV tPA, and among those 157, 86% were screened with multimodal MRI before IV tPA treatment. The rate of IV tPA use during the study period was unchanged.

There was a statistically significant 40% reduction in median DTN time, from 93 to 55 minutes (P < .0001). As well, there was a 4-fold increase in the proportion of patients treated with IV tPA within 60 minutes, from 13.0% in the first half of 2012 to 61.5% in the last half of 2013.

The improvements, which were seen at both hospitals, were largely attributable to the faster door-to-MRI start time.

In-hospital mortality, discharge to home, inpatient rehabilitation rates, and modified Rankin Scale score were not statistically different across the study outcome.

Stroke Outcome

The study, however, did not assess stroke outcome. "That's essential for future studies," said Dr Hsia. "It's something we do need to show, and the only way to do it really is to randomize people to either CT or MRI."

MRI has several advantages over CT. "It provides a much more complete picture" of what's happening in the brain at the time of the stroke, especially in the early minutes and hours of a stroke, said Dr Hsia. "The CT either is not showing you at all the early stroke injury or it's very subtle and can be difficult to visualize."

MRI, on the other hand, "shows you the actual stroke so you can visualize the disease you're aiming to treat," she said.

The MRI scan can also provide information "about blood flow status, blood vessel blockage status and other things that may put a patient at higher risk from tPA like old bleeds," she added.

Being able to visualize the disease is important because it can cut down on stroke "mimics," she noted. None of the patients treated with tPA in at the two hospitals had stroke mimics.

"We were able to show that even by dramatically reducing our treatment time, we did not have an increased number of patients who were getting essentially inappropriate treatment with tPA, so we maintained safety."

Dr Hsia said she recently came across a study that indicated that close to a third of patients treated with tPA didn't actually have a stroke.

Dr Hsia doesn't think that using MRI to screen stroke patients will add to the cost of care. She pointed out that every stroke patient gets an MRI at some point during the hospital stay. "So the question is, when are they going to get it — before they get treated with tPA or at 24 or 48 hours into their hospitalization?"

She added that the radiation risk associated with CT is eliminated with use of MRI.

Another possible benefit of using MRI as a screening tool is reduced length of hospital stay. "From the very beginning, you get information that could guide you as to what might be the underlying cause of the stroke, which much of the hospitalization is spent doing in terms of diagnostic tests. Sorting out what the underlying cause might be and what interventions or medicines you need to get that patient on for secondary stroke prevention gives you a kind of leg up."

The encouraging study results were a result of quality improvement initiatives in which "key leaders" from all hospital departments were involved, commented Dr Hsia. Together with her colleagues, she's continuing to gather data and hopes that the process will be sustained. An app allowing for real time feedback should "help us keep tabs on the process," she said.

"Not Too Far Down the Road"

In an accompanying editorial, Andria L. Ford, MD, from the Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, and Ronen R. Leker, MD, from the Department of Neurology, Hadassah-Hebrew University Medical Center in Jerusalem, Israel, write that, "Despite the clear need for further work, MRI for tPA decision-making may not be too far down the road.

"The current study reminds us of the dramatic effects on DTN times generated from focused, team-based quality improvement measures incorporating lean manufacturing principles—implementation can yield these beneficial effects within a short amount of time," they write. "As technology advances, with faster parallel processing and tailoring of pulse sequences to maximize clinical yield, scanner times continue to decrease, allowing faster and more accurate treatment.

"While CT remains the standard of care for acute tPA decision-making," they conclude, "continued work toward utilizing and interpreting MRI in a streamlined manner may eventually provide patients with the best care, balancing both time and accuracy."

Asked to comment on the new findings, Philip Gorelick, MD, professor, translational science and molecular medicine, Michigan State University College of Human Medicine, and medical director, Mercy Health Hauenstein Neurosciences, Grand Rapids, Michigan, told Medscape Medical News that a "key take-away message," is that work flow processes can be improved to more efficiently deliver IV tPA to patients with acute ischemic stroke.

This, he said, can be done "by thoughtful and careful assessment" of current practices focusing on means to reduce unnecessary or time-consuming steps to obtain neuroimaging.

"In large artery acute ischemic stroke patients, each minute wasted is estimated to cost the patient almost 2 million neurons," Dr Gorelick said. "Neither the patient nor care providers can afford to lose any time in the delivery of intravenous tPA. Provision of the most efficient processes for care delivery is paramount."

Adding his views on the use of MRI in stroke screening, Ralph Sacco, MD, professor and chair of neurology, executive director McKnight Brain Institute, and chief of neurology, Miller School of Medicine, University of Miami, Florida, said part of the decision about which acute stroke imaging modality to use depends on local access and protocol issues.  

"Having a MRI available in the ED helps, but there are still some timing delays where MRI acquisition at present takes longer than CT," said Dr Sacco. "The demands for more rapid and efficient acute stroke imaging are even greater now in the wake of the multiple positive stent retriever trials."

The stent expands the interior walls of the artery and allows blood to get to the patient's brain immediately to prevent as much brain damage as possible. The clot seeps into the mesh of the stent. Then, after five minutes, the stent and clot are removed together. The stent expands the interior walls of the artery and allows blood to get to the patient's brain immediately to prevent as much brain damage as possible. The clot seeps into the mesh of the stent. Then, after five minutes, the stent and clot are removed together.

Each stroke team should review local imaging protocols and create process improvement programs with whatever imaging modality works best for their stroke center to minimize delays and maximize the information they need to make acute stroke treatment decisions, said Dr Sacco.  

The research was supported by the Division of Intramural Research of the National Institute of Neurological Disorders and Stroke, National Institutes of Health. Dr Hsia has disclosed no relevant financial relationships.

Neurology. Published online May 13, 2015. Abstract Editorial

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