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Published on: September 20, 2015
Perfusion-weighted MRI as a marker of response to treatment in acute and subacute stroke
A E Hillis1, R J Wityk, N J Beauchamp
1Department of Cognitive Science, Johns Hopkins Hospital, Baltimore, MD 21287, USA. argye@JHMI.edu
Abstract:
We carried out baseline and short-term follow-up MRI, including perfusion-weighted imaging (PWI) and tests of neurologic and cognitive function on 15 consecutive patients with large-vessel ischemic stroke who showed a persistent large perfusion-diffusion mismatch at enrollment up to seven days after the onset of symptoms. Of these, ten underwent induced blood pressure elevation with phenylephrine and oral medications (in eight) or intravenous fluids (in two) with the goal of improving perfusion; five had no such treatment. Significant functional improvement was defined by a reduction of 3 or more points on the NIH stroke scale (NIHSS). Significant improvement in perfusion was defined by a reduction in the volume of hypoperfused brain by 30 cc on PWI using time-to-peak (TTP) maps, without enlargement of the infarct. There was a strong, statistically significant association between improved function and improved perfusion: six (75%) of eight patients who improved in function, but none of the seven who did not, showed a reduction in volume of hypoperfused brain. All six patients who met the perfusion goal, and only two (22%) of nine who did not showed significant functional improvement (Fisher's exact: P < 0.01). There were no differences between patients who improved functionally and those who did not with respect to age, initial volume of abnormality on DWI or PWI, initial NIHSS, or changes on DWI. These findings indicate that reduction in volume of hypoperfused brain on PWI is a marker of response to treatment to improve perfusion even in subacute stroke and that partial reperfusion of regions of salvageable but dysfunctional tissue is a mechanism of improved function associated with induced blood pressure elevation.
Insights
Induced blood pressure elevation in large-vessel ischemic stroke patients improved perfusion and function. Reduced hypoperfused brain volume on perfusion-weighted imaging (PWI) indicated treatment response and functional recovery.
Area of Science:
- Neurology
- Radiology
- Cardiovascular Medicine
Background:
- Large-vessel ischemic stroke presents a significant clinical challenge.
- Perfusion-diffusion mismatch indicates salvageable brain tissue.
- Early reperfusion strategies are crucial for improving outcomes.
Purpose of the Study:
- To assess the association between improved perfusion and functional outcomes in subacute stroke patients.
- To determine if reduction in hypoperfused brain volume on perfusion-weighted imaging (PWI) is a marker of treatment response.
- To investigate the mechanism of functional improvement following induced blood pressure elevation.
Main Methods:
- MRI including perfusion-weighted imaging (PWI) and neurologic/cognitive function tests were performed on 15 large-vessel ischemic stroke patients.
- Ten patients received induced blood pressure elevation; five served as controls.
- Significant functional improvement was defined as ≥3-point reduction in NIH Stroke Scale (NIHSS).
- Significant perfusion improvement was defined as ≥30 cc reduction in hypoperfused brain volume on PWI (time-to-peak maps) without infarct expansion.
Main Results:
- A strong, statistically significant association was found between improved function and improved perfusion (Fisher's exact: P < 0.01).
- Six of eight patients (75%) with functional improvement showed reduced hypoperfused brain volume.
- All six patients achieving the perfusion goal demonstrated significant functional improvement.
- No significant differences were observed in baseline characteristics or diffusion-weighted imaging (DWI) changes between functional improvers and non-improvers.
Conclusions:
- Reduction in hypoperfused brain volume on PWI serves as a marker for treatment response in subacute stroke.
- Induced blood pressure elevation can lead to partial reperfusion of salvageable tissue, driving functional improvement.
- Perfusion improvement is a key mechanism for enhanced neurological function in treated ischemic stroke patients.
