Deans' stroke musings: Risk Factors of Hypoperfusion on MRI of Ischemic Stroke Patients Within 7 Days of Onset

Changing stroke rehab and research worldwide now.Time is Brain! trillions and trillions of neurons that DIE each day because there are NO effective hyperacute therapies besides tPA(only 12% effective). I have 523 posts on hyperacute therapy, enough for researchers to spend decades proving them out. These are my personal ideas and blog on stroke rehabilitation and stroke research. Do not attempt any of these without checking with your medical provider. Unless you join me in agitating, when you need these therapies they won't be there.

What this blog is for:

My blog is not to help survivors recover, it is to have the 10 million yearly stroke survivors light fires underneath their doctors, stroke hospitals and stroke researchers to get stroke solved. 100% recovery. The stroke medical world is completely failing at that goal, they don't even have it as a goal. Shortly after getting out of the hospital and getting NO information on the process or protocols of stroke rehabilitation and recovery I started searching on the internet and found that no other survivor received useful information. This is an attempt to cover all stroke rehabilitation information that should be readily available to survivors so they can talk with informed knowledge to their medical staff. It lays out what needs to be done to get stroke survivors closer to 100% recovery. It's quite disgusting that this information is not available from every stroke association and doctors group.

Friday, May 14, 2021

Risk Factors of Hypoperfusion on MRI of Ischemic Stroke Patients Within 7 Days of Onset

Hypoperfusion is a term that describes "a reduced amount of blood flow". I have zero understanding of what is going on here. Were none of these patients treated with tPA or thrombectomy?

Risk Factors of Hypoperfusion on MRI of Ischemic Stroke Patients Within 7 Days of Onset

Jingjing Xiao¹^†,

Huazheng Liang^1,2^†,

Yue Wang¹,

Shaoshi Wang¹,

Yi Wang^1,3 and

Yong Bi¹^*

¹Department of Neurology, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, China
²Department of Neurology, Translational Research Institute of Brain and Brain-Like Intelligence, Shanghai Fourth People's Hospital Affiliated to Tongji University School of Medicine, Shanghai, China
³College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China

Objective: Hypoperfusion is an important factor determining the prognosis of ischemic stroke patients. The present study aimed to investigate possible predictors of hypoperfusion on MRI of ischemic stroke patients within 7 days of stroke onset.

Methods: Ischemic stroke patients, admitted to the comprehensive Stroke Center of Shanghai Fourth People's Hospital affiliated to Tongji University within 7 days of onset between January 2016 and June 2017, were recruited to the present study. Magnetic resonance imaging (MRI), including both diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI), was performed within 7 days of the symptom onset. Time to maximum of the residue function (T_max) maps were automatically evaluated using the RAPID software. The volume of hypoperfusion was measured outside the infarct area based on ADC < 620 × 10⁻⁶ mm²/s. The 90 d mRS score was assessed through either clinic visits or telephone calls. Multivariate step-wise analysis was used to assess the correlation between MR findings and clinical variables, including the demographic information, cardio-metabolic characteristics, and functional outcomes.

Results: Among 635 patients admitted due to acute ischemic stroke within 7 days of onset, 241 met the inclusion criteria. Hypoperfusion volume of 38 ml was the best cut-off value for predicting poor prognosis of patients with cerebral infarction (90 d-mRS score ≥ 2). The incidences of MR perfusion T_max > 4–6 s maps with a volume of 0–38 mL or >38 mL were 51.9% (125/241) and 48.1% (116/241), respectively. Prior stroke and vascular stenosis (≥70%) were associated with MR hypoperfusion. Multivariate step-wise analysis showed that prior stroke and vascular stenosis (≥70%) were risk factors of T_max > 4–6 s maps, and the odds ratios (OR) were 3.418 (adjusted OR 95% CI: 1.537–7.600), and 2.265 (adjusted OR, 95% CI: 1.199–4.278), respectively.

Conclusion: Our results suggest that prior stroke and vascular stenosis (≥70%) are strong predictors of hypoperfusion in patients with acute ischemic stroke within 7 days of stroke onset.

Introduction

Intravenous thrombolysis and endovascular therapy are effective methods for the treatment of acute ischemic stroke (1, 2). However, due to time window restrictions, only a small number of people receive timely treatment, and over 70% of stroke patients still have disabilities (modified Rankin classification, mRS2-6) due to the presence of hypoperfused tissues (3, 4). Quantitative assessment of hemodynamic indices of acute stroke patients will facilitate the discovery of potential predictors of hypoperfusion, which will reveal new targets for early and effective intervention. Currently, a number of factors have been reported to influence functional outcomes of acute ischemic stroke patients, including blood glucose, blood pressure, history of atrial fibrillation, baseline NIHSS, volume of core infarction, blood perfusion, and vascular lesions (5–12). Previous studies have shown that abnormal brain perfusion is closely related to stroke recurrence and functional outcome, but there are few studies on risk factors impacting brain perfusion.

T_max is a widely used parameter of magnetic resonance perfusion for patients with acute ischemic stroke and has been used in clinical trials (13, 14). Different T_max thresholds reflect different degrees of hypoperfused volumes, with a high threshold reflecting a low degree of hypoperfusion (15). Changes of T_max may reflect the microvascular integrity of collaterals and the perfusion status of brain tissue (16). In view of the fact that perfusion imaging is closely related to the status of collateral circulation, the cerebral perfusion parameters on MRI may be a good biomarker of collateral circulation. Therefore, it is reasonable to use T_max to evaluate the status of tissue hypoperfusion and facilitate decision-making on the choice of treatments for patients with AIS (17–19).

It is well-known that the penumbra is the area surrounding the ischemic core, which has a high risk of progressing to infarct. T_max > 6 s can accurately define the penumbra (20). Albers et al. screened patients with salvageable penumbra for endovascular thrombectomy using T_max > 6 s with the assistance of the RAPID software (17). Time to peak contrast concentration (TTP) or time at which the deconvolved residue function reaches its maximum value (T_max) is generally used to evaluate hypoperfusion status. Compared with TTP, T_max has the advantage of reducing dependence on bolus shape and cardiac output (21). Therefore, T_max seems to be more appropriate in evaluating tissue lesions with hypoperfusion. It has been reported that T_max > 6 s or T_max > 4 s is more accurate than T_max > 2 s in predicting the salvageable penumbra or stroke progression. Difference between the volumes of T_max > 4 s and T_max > 6 s seems to be the best biomarker in identifying severe hypoperfusion (22). Studies have shown benefit from prolonged reperfusion therapy with increased likelihood of good prognosis through evaluating the ischemic penumbra with the perfusion parameter T_max (17, 19). However, few studies have reported risk factors of low perfusion in Chinese populations. Therefore, the present study aimed to quantitatively evaluate the hypoperfusion status of AIS patients and to explore the potential predictors of hypoperfusion on MRI.