The Spatiotemporal Evolution of MRI-Derived Oxygen Extraction Fraction and Perfusion in Ischemic Stroke

Abstract

PurposeThis study aimed to assess the spatiotemporal evolution of oxygen extraction fraction (OEF) in ischemic stroke with a newly developed cluster analysis of time evolution (CAT) for a combined quantitative susceptibility mapping and quantitative blood oxygen level-dependent model (QSM + qBOLD, QQ).MethodOne hundred and fifteen patients in different ischemic stroke phases were retrospectively collected for measurement of OEF of the infarcted area defined on diffusion-weighted imaging (DWI). Clinical severity was assessed using the National Institutes of Health Stroke Scale (NIHSS). Of the 115 patients, 11 underwent two longitudinal MRI scans, namely, three-dimensional (3D) multi-echo gradient recalled echo (mGRE) and 3D pseudo-continuous arterial spin labeling (pCASL), to evaluate the reversal region (RR) of the initial diffusion lesion (IDL) that did not overlap with the final infarct (FI). The temporal evolution of OEF and the cerebral blood flow (CBF) in the IDL, the RR, and the FI were assessed.ResultsCompared to the contralateral mirror area, the OEF of the infarcted region was decreased regardless of stroke phases (p < 0.05) and showed a declining tendency from the acute to the chronic phase (p = 0.022). Five of the 11 patients with longitudinal scans showed reversal of the IDL. Relative oxygen extraction fraction (rOEF, compared to the contralateral mirror area) of the RR increased from the first to the second MRI (p = 0.044). CBF was about 1.5-fold higher in the IDL than in the contralateral mirror area in the first MRI. Two patients showed penumbra according to the enlarged FI volume. The rOEF of the penumbra fluctuated around 1.0 at earlier scan times and then decreased, while the CBF decreased continuously.ConclusionThe spatiotemporal evolution of OEF and perfusion in ischemic lesions is heterogeneous, and the CAT-based QQ method is feasible to capture cerebral oxygen metabolic information.

Brain oxygen extraction and neural tissue susceptibility are associated with cognitive impairment in older individuals

“…MR-based OEF mapping has shown high agreement with OEF mapping using 15 O-PET 27,29 and is more easily implemented, since it utilizes a routinely available MR sequence without injection of tracers. Clinical feasibility of QQ has been shown in the settings of ischemic stroke 30,31 and multiple sclerosis. 32 As QQ further divides voxel-wise susceptibility into the effect of deoxyheme iron in a cylindrical micron-scale venule (OEF effect) and that of neural tissue susceptibility (χ n ) derived from diffuse nanoscale ferritin iron in tissue, 24 it can provide a comprehensive picture of both tissue oxygenation and iron.…”

Cerebral blood flow quantification with multi-delay arterial spin labeling in ischemic stroke and the association with early neurological outcome

“…However, in our study, hyperperfusion was also seen in viable salvaged penumbra, albeit less frequent and to a lesser extent. It may thus be worthwhile to complement post-recanalization assessment of CBF with metabolic parameters such as oxygen extraction fraction and cerebral metabolic rate of oxygen ( Fan et al, 2020 , Wu et al, 2021 ). These parameters are measures of the extent to which oxygen is extracted from arterial blood and the rate of oxygen consumption, respectively, and thus reflect tissue metabolism ( Lin and Powers, 2018 ).…”

Radiomics-based infarct features on CT predict hemorrhagic transformation in patients with acute ischemic stroke

“…Previous studies have shown that the occurrence of HT is mainly related to damage to the blood–brain barrier in the infarcted areas, reperfusion injury and coagulation disorders ( Bai and Lyden, 2015 ; Yang et al, 2019 ; Zheng et al, 2019 ; Spronk et al, 2021 ). For AIS patients, the state of the blood–brain barrier in the cerebral infarction areas changes dynamically with the stroke onset time, the location and degree of thrombus, the infarct size and the body’s own physiological and pathological changes; consequently, different changes will appear on imaging ( Wu et al, 2021 ). Compared with human visual analysis, radiomics features can more fully reflect the microscopic differences within the lesion and thus better evaluate the state of blood–brain barrier damage ( Kassner et al, 2009 ; Valdés Hernández et al, 2017 ).…”