TY - JOUR
T1 - Imaging the physiological evolution of the ischemic penumbra in acute ischemic stroke
AU - Leigh, Richard
AU - Knutsson, Linda
AU - Zhou, Jinyuan
AU - van Zijl, Peter C.M.
N1 - Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by NINDS Intramural Research Program, NIH (RL), P41EB015909 (PvZ), RO1NS083435 (JZ).
Funding Information:
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: van Zijl and Zhou report grants from NIH. Knutsson has grants from the Swedish Research Council. In addition, van Zijl and Zhou have a patent on APT-weighted MRI for pH imaging with royalties paid by Philips. van Zijl also has a patent on VASO MRI for CBV imaging licensed to Philips. Leigh has no conflicts to report.
Publisher Copyright:
© The Author(s) 2017.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - We review the hemodynamic, metabolic and cellular parameters affected during early ischemia and their changes as a function of approximate cerebral blood flow (CBF) thresholds. These parameters underlie the current practical definition of an ischemic penumbra, namely metabolically affected but still viable brain tissue. Such tissue is at risk of infarction under continuing conditions of reduced CBF, but can be rescued through timely intervention. This definition will be useful in clinical diagnosis only if imaging techniques exist that can rapidly, and with sufficient accuracy, visualize the existence of a mismatch between such a metabolically affected area and regions that have suffered cell depolarization. Unfortunately, clinical data show that defining the outer boundary of the penumbra based solely on perfusion-related thresholds may not be sufficiently accurate. Also, thresholds for CBF and cerebral blood volume (CBV) differ for white and gray matter and evolve with time for both inner and outer penumbral boundaries. As such, practical penumbral imaging would involve parameters in which the physiology is immediately displayed in a manner independent of baseline CBF or CBF threshold, namely pH, oxygen extraction fraction (OEF), diffusion constant and mean transit time (MTT). Suitable imaging technologies will need to meet this requirement in a 10–20 min exam.
AB - We review the hemodynamic, metabolic and cellular parameters affected during early ischemia and their changes as a function of approximate cerebral blood flow (CBF) thresholds. These parameters underlie the current practical definition of an ischemic penumbra, namely metabolically affected but still viable brain tissue. Such tissue is at risk of infarction under continuing conditions of reduced CBF, but can be rescued through timely intervention. This definition will be useful in clinical diagnosis only if imaging techniques exist that can rapidly, and with sufficient accuracy, visualize the existence of a mismatch between such a metabolically affected area and regions that have suffered cell depolarization. Unfortunately, clinical data show that defining the outer boundary of the penumbra based solely on perfusion-related thresholds may not be sufficiently accurate. Also, thresholds for CBF and cerebral blood volume (CBV) differ for white and gray matter and evolve with time for both inner and outer penumbral boundaries. As such, practical penumbral imaging would involve parameters in which the physiology is immediately displayed in a manner independent of baseline CBF or CBF threshold, namely pH, oxygen extraction fraction (OEF), diffusion constant and mean transit time (MTT). Suitable imaging technologies will need to meet this requirement in a 10–20 min exam.
KW - Acidosis
KW - MRI
KW - ischemic penumbra
KW - metabolism
KW - pH
KW - perfusion
KW - physiologic evolution
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U2 - 10.1177/0271678X17700913
DO - 10.1177/0271678X17700913
M3 - Review article
C2 - 28345479
AN - SCOPUS:85027565310
SN - 0271-678X
VL - 38
SP - 1500
EP - 1516
JO - Journal of Cerebral Blood Flow and Metabolism
JF - Journal of Cerebral Blood Flow and Metabolism
IS - 9
ER -