Refined Ischemic Penumbra Imaging with Tissue pH and Diffusion Kurtosis Magnetic Resonance Imaging

• Type of Material: Article
• Authors: Jesse Cheung, Emory University; Madelin Doerr, Emory University; Ranliang Hu, Emory University; Phillip Zhe Sun, Emory University
• Language: English
• Date: 2020-11-07
• Publisher: SPRINGER
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020, Springer Science Business Media, LLC, part of Springer Nature
• License: Creative Commons Attribution-NonCommercial 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1007/s12975-020-00868-z
• Title of Journal or Parent Work: TRANSLATIONAL STROKE RESEARCH
• Volume: 12
• Issue: 5
• Start Page: 742
• End Page: 753
• Grant/Funding Information: This study was supported in part by grants from NIH/NINDS 2R01NS083654 (to Sun) and Emory University Synergy Grant (to Hu and Sun).
• Keywords: INTRACELLULAR PH; ENDOVASCULAR REPERFUSION; pH MRI; Neurosciences; Clinical Neurology; Life Sciences & Biomedicine; Penumbra; Acidification; EVOLVING PARADIGMS; Neurosciences & Neurology; Diffusion kurtosis imaging (DKI); Acute stroke; ACUTE STROKE PATIENTS; MRI mismatch; Science & Technology; AMIDE PROTON-TRANSFER; LESION REVERSAL; SPIN-LABELING PERFUSION; WHITE-MATTER; CEREBRAL-BLOOD-FLOW; ANIMAL-MODEL

Abstract

Imaging has played a vital role in our mechanistic understanding of acute ischemia and the management of acute stroke patients. The most recent DAWN and DEFUSE-3 trials showed that endovascular therapy could be extended to a selected group of late-presenting stroke patients with the aid of imaging. Although perfusion and diffusion MRI have been commonly used in stroke imaging, the approximation of their mismatch as the penumbra is oversimplified, particularly in the era of endovascular therapy. Briefly, the hypoperfusion lesion includes the benign oligemia that does not proceed to infarction. Also, with prompt and effective reperfusion therapy, a portion of the diffusion lesion is potentially reversible. Therefore, advanced imaging that provides improved ischemic tissue characterization may enable new experimental stroke therapeutics and eventually further individualize stroke treatment upon translation to the clinical setting. Specifically, pH imaging captures tissue of altered metabolic state that demarcates the hypoperfused lesion into ischemic penumbra and benign oligemia, which remains promising to define the ischemic penumbra’s outer boundary. On the other hand, diffusion kurtosis imaging (DKI) differentiates the most severely damaged and irreversibly injured diffusion lesion from the portion of diffusion lesion that is potentially reversible, refining the inner boundary of the penumbra. Altogether, the development of advanced imaging has the potential to not only transform the experimental stroke research but also aid clinical translation and patient management.