Delayed perfusion phenomenon in a rat stroke model at 1.5T MR: An imaging sign parallel to spontaneous reperfusion and ischemic penumbra?

Chen, Feng; Suzuki, Yasuhiro; Nagai, Nobuo; Sun, Xihe; Coudyzer, Walter; Yu, Jie; Marchal, Guy; Ni, Yicheng

doi:10.1016/j.ejrad.2006.08.019

« Previous Next »European Journal of Radiology
Volume 61, Issue 1 , Pages 70-78, January 2007

Delayed perfusion phenomenon in a rat stroke model at 1.5T MR: An imaging sign parallel to spontaneous reperfusion and ischemic penumbra?

Feng Chen
- Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
- Department of Radiology, Zhong Da Hospital, Southeast University, 87 Ding Jia Qiao Road, Nanjing 210009, Jiangsu Province, China
Yasuhiro Suzuki
- Department of Molecular and Cellular Medicine, Faculty of Medicine, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
- Department of Pharmacology, Hamamatsu University School of Medicine, 1-20-1 Handayama, 431-3192 Hamamatsu, Japan
Nobuo Nagai
- Department of Molecular and Cellular Medicine, Faculty of Medicine, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
Xihe Sun
- Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
- Department of Radiology, the Affiliated Hospital of Weifang Medical University, Weifang 261031, Shandong Province, China
Walter Coudyzer
- Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
Jie Yu
- Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
Guy Marchal
- Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
Yicheng Ni
- Department of Radiology, University Hospitals, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
- Corresponding author. Tel.: +32 16 345940; fax: +32 16 343765.

Received 14 June 2006; received in revised form 14 August 2006; accepted 16 August 2006.

Abstract

Introduction

Delayed perfusion (DP) sign at MR imaging was reported in stroke patients. We sought to experimentally elucidate its relation to spontaneous reperfusion and ischemic penumbra.

Methods

Stroke was induced by photothrombotic occlusion of middle cerebral artery in eight rats and studied up to 72h using a 1.5T MR scanner with T2 weighted imaging (T2WI), diffusion weighted imaging (DWI), and dynamic susceptibility contrast-enhanced perfusion weighted imaging (DSC-PWI). Relative signal intensity (rSI), relative lesion volume (rLV), relative cerebral blood flow (rCBF), PWI_rLV–DWI_rLV mismatch (penumbra) and DP_rLV were quantified and correlated with neurological deficit score (NDS), triphenyl tetrazolium chloride (TTC) staining, microangiography (MA) and histopathology.

Results

The rSI and rLV characterized this stroke model on different MRI sequences and time points. DSC-PWI reproduced cortical DP in all rats, where rCBF evolved from 88.9% at 1h through 64.9% at 6h to 136.3% at 72h. The PWI_rLV–DWI_rLV mismatch reached 10±5.4% at 1h, remained positive through 12h and decreased to −3.3±4.5% at 72h. The incidence and rLV of the DP were well correlated with those of the penumbra (p<0.01, r²=0.85 and p<0.0001, r²=0.96, respectively). Shorter DP durations and more collateral arterioles occurred in rats without (n=4) than with (n=4) cortex involvement (p<0.05). Rats without cortex involvement tended to earlier reperfusion and a lower NDS. Microscopy confirmed MRI, MA and TTC findings.

Conclusions

In this rat stroke model, we reproduced clinically observed DP on DSC-PWI, confirmed spontaneous reperfusion, and identified the penumbra extending to 12h post-ischemia, which appeared interrelated.

Keywords: Ischemia, Stroke, Rats, Magnetic resonance imaging, Contrast enhancement, Experimental