Volume 51, Issue 6 pp. 1138-1146
Full Paper

Acute cerebral ischemia in rats studied by Carr-Purcell spin-echo magnetic resonance imaging: Assessment of blood oxygenation level-dependent and tissue effects on the transverse relaxation

Martin Kavec

Martin Kavec

Department of Biomedical NMR and National Bio-NMR Facility, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland

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Olli H.J. Gröhn

Olli H.J. Gröhn

Department of Biomedical NMR and National Bio-NMR Facility, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland

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Mikko I. Kettunen

Mikko I. Kettunen

Department of Biomedical NMR and National Bio-NMR Facility, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland

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M. Johanna Silvennoinen

M. Johanna Silvennoinen

Department of Biomedical NMR and National Bio-NMR Facility, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland

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Michael Garwood

Michael Garwood

Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota

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Risto A. Kauppinen

Corresponding Author

Risto A. Kauppinen

Department of Biomedical NMR and National Bio-NMR Facility, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland

School of Biological Sciences, University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester M13 9PT, UK===Search for more papers by this author
First published: 24 May 2004
Citations: 13

Abstract

Acute cerebral ischemia has been shown to be associated with an enhanced transverse relaxation rate in rat brain parenchyma, chiefly due to the blood oxygenation level-dependent (BOLD) effect. In this study, Carr-Purcell R2 (CP R2), acquired both with short and long time intervals between centers of adiabatic π-pulses (τCP), was used to assess the contributions of BOLD and tissue effects to the transverse relaxation in two brain ischemia models of rat at 4.7 T. R and diffusion MR images were also acquired in the same animals. During the first minutes of global ischemia, the long τCP R2 in brain parenchyma increased, whereas the short τCP R2 was unchanged. Based on the simulations, and using constraints of intravascular BOLD effect on parenchymal R2, the former observation was ascribed to be due to susceptibility changes arising in the extravascular compartment. R declined almost immediately after the onset of focal cerebral ischemia, and further declined during the evolution of ischemic damage. Interestingly, short τCP CP R2 started to decline after some 20 min of focal ischemia and declined over a time course similar to that of R, indicating that it may be an MRI marker for irreversible tissue changes in cerebral ischemia. The present results show that CP R2 MRI can reveal both tissue- and blood-derived contrast changes in acute cerebral ischemia. Magn Reson Med 51:1138–1146, 2004. © 2004 Wiley-Liss, Inc.

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