Estimation of the onset time of cerebral ischemia using T1ρ and T2 MRI in rats

Kimmo T. Jokivarsi, Yrjö Hiltunen, Heidi Gröhn, Pasi Tuunanen, Olli H.J. Gröhn, Risto A. Kauppinen

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Background And Purpose-: Time of ischemia onset is the most critical factor for patient selection for available drug treatment strategies. The purpose of this study was to evaluate the abilities of the absolute longitudinal rotating frame (T1ρ) and transverse (T2) MR relaxation times to estimate the onset time of ischemia in rats. Methods-: Permanent middle cerebral artery occlusion in rats was used to induce focal cerebral ischemia and animals were imaged with multiparametric MRI at several time points up to 7 hours postischemia. Ischemic parenchyma was defined as tissue with apparent diffusion coefficient of water <70% from that in the contralateral nonischemic brain. Results-: The difference in the absolute T1ρ and T2 between ischemic and contralateral nonischemic striatum increased linearly within the first 6 hours of middle cerebral artery occlusion. The slopes for T1ρ and T2 fits for both tissue types were similar; however, the time offsets were significantly longer for both MR parameters in the cortex than in the striatum. Conclusions-: T1ρ and T2 MRI provide estimates for the onset time of cerebral ischemia requiring regional calibration curves from ischemic brain. Assuming that patients with suspected ischemic stroke are scanned by MRI within this timeframe, these MRI techniques may constitute unbiased tools for stroke onset time evaluation potentially aiding the decision-making for drug treatment strategies.

Original languageEnglish (US)
Pages (from-to)2335-2340
Number of pages6
Issue number10
StatePublished - Oct 2010
Externally publishedYes


  • MRI
  • acute stroke
  • animal models
  • brain imaging
  • brain ischemia


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