MRI algorithm may ID stroke patients at risk of major bleeding

Physicians treating ischemic stroke one day may be able to determine patients’ risk for developing severe intracranial bleeding using an algorithm applied to standard MRI scans.

Richard Leigh, MD, of Johns Hopkins University in Baltimore, and colleagues reviewed 75 patient cases available through the Stroke Imaging Repository (STIR) and Virtual International Stroke Trials Archive (VISTA) to determine a means of separating out patients at risk for developing a parenchymal hematoma (PH). While only a small number of cases develop into PH, patients who do have the poorest overall outcomes, often leading to death.

They divided the patient population into three groups: 47 who did not develop an intracranial hemorrhage (ICH), 19 who developed a hemorrhagic infarction, and nine cases where patients developed PH. Most patients (67) were treated with tPA within a three-hour window; all patients received administered tissue-type plasminogen activator (tPA) within the 4.5-hour window for administering the treatment.

“[I]n our study, a novel algorithm, which uses an arrival time correction, was used in a quantitative manner,” they wrote. “The advantage to this approach is that it removes the effects of blood flow and dispersion from the recorded signal, allowing an index related to BBB [blood-brain barrier] permeability to be estimated.”

All patients were determined to have some form of damage to the BBB via MRI following a per-voxel examination of the scans taken at multiple time points upon admission.

While it was not possible to differentiate between the BBB damage and hemorrhagic transformation between those likely to experience minor to no bleeding, a difference could be seen between minor and major bleeding. This could have an impact in treatment with tPA.

“Leakage of gadolinium [seen through the MRI], a substance that generally does not penetrate an intact blood-brain barrier, into the brain parenchyma was used as a measure of blood-brain barrier damage,” wrote Leigh et al. “Larger amounts of gadolinium accumulation were a marker for more severe ICH when exposed to tPA.”

Leigh and colleagues noted that blood brain barrier damage accounted for only a small amount of hemorrhagic transformation post-tPA administration but that they identified a threshold for major bleeding. “This is an intriguing finding because major bleeding, and not minor bleeding, is the complication of tPA that is most feared.”

Researchers saw a significant association with the degree of ICH according to the European Cooperative Acute Stroke Study criteria grading and mean permeability derangement, glucose level on admission, a history of coronary artery disease and baseline National Institute of Health Stroke Score. Mean permeability derangement and glucose level on admission were the only independent predictors of ICH severity.

As of yet, these findings have only been applied retrospectively and have not been used for prognosis. However, this study poses possibilities for future clinical application. Leigh stated, “This study is not powered to establish such a threshold as predictive, but a subsequent study in which this threshold is tested on a unique population may clarify the clinical use of this finding.”

The study was published May 15 in Stroke.