Articles from Stroke

Link to journal online
Toth, Gabor ; Albers, Gregory W.
Use of MRI to Estimate the Therapeutic Window in Acute Stroke: Is Perfusion-Weighted Imaging/Diffusion-Weighted Imaging Mismatch an EPITHET for Salvageable Ischemic Brain Tissue?
Source
Stroke. 40(1):333-335, January 2009.

Cai, Weibo ; Guzman, Raphael ; Hsu, Andrew R. ; Wang, Hui ; Chen, Kai et al
Positron Emission Tomography Imaging of Poststroke Angiogenesis
Stroke. 40(1):270-277, January 2009.
Abstract
Background and Purpose-: Vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) play important roles during neurovascular repair after stroke. In this study, we imaged VEGFR expression with positron emission tomography (PET) to noninvasively analyze poststroke angiogenesis.Methods-: Female Sprague-Dawley rats after distal middle cerebral artery occlusion surgery were subjected to weekly MRI, 18F-FDG PET, and 64Cu-DOTA-VEGF121 PET scans. Several control experiments were performed to confirm the VEGFR specificity of 64Cu-DOTA-VEGF121 uptake in the stroke border zone. VEGFR, BrdU, lectin staining, and 125I-VEGF165 autoradiography on stroke brain tissue slices were performed to validate the in vivo findings.Results-: T2-weighed MRI correlated with the "cold spot" on 18F-FDG PET for rats undergoing distal middle cerebral artery occlusion surgery. The 64Cu-DOTA-VEGF121 uptake in the stroke border zone peaked at [almost equal to]10 days after surgery, indicating neovascularization as confirmed by histology (VEGFR-2, BrdU, and lectin staining). VEGFR specificity of 64Cu-DOTA-VEGF121 uptake was confirmed by significantly lower uptake of 64Cu-DOTA-VEGFmutant in vivo and intense 125I-VEGF165 uptake ex vivo in the stroke border zone. No appreciable uptake of 64Cu-DOTA-VEGF121 was observed in the brain of sham-operated rats.Conclusions-: For the first time to our knowledge, we successfully evaluated the VEGFR expression kinetics noninvasively in a rat stroke model. In vivo imaging of VEGFR expression could become a significant clinical tool to plan and monitor therapies aimed at improving poststroke angiogenesis.

Izquierdo-Garcia, David ; Davies, John R. ; Graves, Martin J. et al
Comparison of Methods for Magnetic Resonance-Guided [18-F]Fluorodeoxyglucose Positron Emission Tomography in Human Carotid Arteries: Reproducibility, Partial Volume Correction, and Correlation Between Methods.
Stroke. 40(1):86-93, January 2009.
Abstract
Background and Purpose-: Inflammation is a major risk factor for atherosclerotic plaque rupture and clinical events. Previous studies have shown that plaque [18F]fluorodeoxyglucose (FDG) uptake correlates with macrophage content. In this study we examined the reproducibility of 3 methods of quantifying plaque FDG uptake in the carotid arteries using positron emission tomography (PET). The correlation between 2 simplified uptake parameters (standardized uptake value [SUV], vessel wall-to-blood ratio [VBR]) and a gold standard technique (influx rate [Ki]) was also determined. We used MRI to correct carotid plaque FDG uptake for partial volume error.Methods-: Seven patients with a recent carotid territory transient ischemic attack underwent imaging twice within 8 days using MR and FDG-PET. MR coregistered to PET was used to delineate regions of interest, and to facilitate partial volume correction (PVC).Results-: SUV was the most reproducible parameter irrespective of whether it was normalized by body surface area (BSA), lean body mass, or weight (intraclass correlation coefficient=0.85, 0.88, and 0.90, respectively). VBR correlated better to Ki than SUV (r=0.58 VBR, r=0.46 SUVBSA). PVC improved these correlations to r=0.81 VBR and r=0.76 SUVBSA, and only slightly degraded the reproducibility of SUV (intraclass correlation coefficient=0.83-0.85).Conclusions-: MR-guided FDG-PET is a highly reproducible technique in the carotid artery and the excellent anatomic detail provided by MR facilitates PVC. Of the methods examined, SUVBSAPVC appears to represent the best compromise between reproducible and accurate determination of FDG metabolism in carotid artery vessel wall.