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24-05-2012 | Surgery | Article

DEFUSE 2: Imaging mismatch could guide endovascular stroke therapy

Abstract

Meeting website

MedWire News: An automated magnetic resonance imaging (MRI) analysis program successfully predicts which patients will benefit from endovascular therapy for acute stroke, show the DEFUSE 2 findings.

The program identified patients who had a high chance of a good clinical response to reperfusion on endovascular therapy, leading to an improved chance of having good long-term functional outcomes.

"I think we are entering a very exciting era, where now the imaging is ready to select these patients in the acute setting, the post-processing is fast enough to make the selection in real time, and our endovascular therapies are continuing to improve, with higher recanalization rates," Maarten Lansberg (Stanford University, California, USA) told attendees at the European Stroke Conference in Lisbon, Portugal.

The RAPID software used in the study processes MRI data to quantify the size of lesion on perfusion-weighted imaging (PWI) and on diffusion-weighted imaging (DWI) and to calculate the ratio of the two sizes. In other words, it calculates the volume of tissue that is potentially salvageable if a patient undergoes reperfusion. The DEFUSE 2 team considered a PWI-to-DWI lesion ratio of 1.8 to represent mismatch.

The team treated 110 patients, 104 of whom had usable MRI data. The median National Institutes of Health Stroke Scale (NIHSS) score was 16, the median time to treatment was 5.9 hours, and 53% of patients were pretreated with intravenous thrombolysis.

Of the treated patients, 78 had an MRI mismatch and 26 did not. About 60% of each group achieved reperfusion, defined as at least a 50% reduction in PWI lesion volume between baseline and follow-up imaging on day 5.

When assessed 30 days after stroke onset, patients with MRI mismatch were fivefold more likely to have a favorable clinical response (≥8 point NIHSS improvement or final score 0-1) if they reperfused than if they did not.

By contrast, reperfusion did not affect outcomes in those without mismatch. The difference remained after accounting for variables including age and the size of the diffusion lesion.

The benefits of reperfusion among patients with mismatch extended to their longer-term outcomes, with 57% of those who reperfused versus 32% of those who did not achieve good 90-day functional outcomes (modified Rankin Scale 0-2).

These differences were explained by the effect of reperfusion on lesion growth; among patients with MRI mismatch, the median lesion growth between baseline and day 5 was 30 mL if they reperfused versus 73 mL if they did not. Reperfusion did not affect functional outcome in patients without MRI mismatch.

Lansberg said that the findings support a randomized trial of endovascular therapy based on MRI selection.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Eleanor McDermid

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