Amide proton transfer–weighted MRI can detect tissue acidosis and monitor recovery in a transient middle cerebral artery occlusion model compared with a permanent occlusion model in rats
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To assess whether increases in amide proton transfer (APT)–weighted signal reflect the effects of tissue recovery from acidosis using transient rat middle cerebral artery occlusion (MCAO) models, compared to permanent occlusion models.
Materials and methods
Twenty-four rats with MCAO (17 transient and seven permanent occlusions) were prepared. APT-weighted signal (APTw), apparent diffusion coefficient (ADC), cerebral blood flow (CBF), and MR spectroscopy were evaluated at three stages in each group (occlusion, reperfusion/1 h post-occlusion, and 3 h post-reperfusion/4 h post-occlusion). Deficit areas showing 30% reduction to the contralateral side were measured. Temporal changes were compared with repeated measures of analysis of variance. Relationship between APTw and lactate concentration was calculated.
Both APTw and CBF values increased and APTw deficit area reduced at reperfusion (largest p = .002) in transient occlusion models, but this was not demonstrated in permanent occlusion. No significant temporal change was demonstrated with ADC at reperfusion. APTw deficit area was between ADC and CBF deficit areas in transient occlusion model. APTw correlated with lactate concentration at occlusion (r = − 0.49, p = .04) and reperfusion (r = − 0.32, p = .02).
APTw values increased after reperfusion and correlated with lactate content, which suggests that APT-weighted MRI could become a useful imaging technique to reflect tissue acidosis and its reversal.
• APT-weighted signal increases in the tissue reperfusion, while remains stable in the permanent occlusion.
• APTw deficit area was between ADC and CBF deficit areas in transient occlusion model, possibly demonstrating metabolic penumbra.
• APTw correlated with lactate concentration during ischemia and reperfusion, indicating tissue acidosis.
KeywordsAcidosis Reperfusion Amides Magnetic resonance imaging
Apparent diffusion coefficient
Amide proton transfer–weighted signal
Cerebral blood flow
Middle cerebral artery occlusion
This study was supported by a grant (2016-690) from the Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
Compliance with ethical standards
The scientific guarantor of this publication is Dong Cheol Woo.
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
We thank Seon Ok Kim for his expertise in statistical analysis.
Approval from the institutional animal care committee was obtained.
This study was approved by the Institutional Animal Care and Use Committee of Asan Medical Center.
• performed at one institution
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