Noninvasive detection of cerebral hypoperfusion and reversible ischemia from reductions in the magnetic resonance imaging relaxation time, T2

Olli H.J. Gröhn, Jouko A. Lukkarinen, Joni M.E. Oja, Peter C.M. Van Zijl, John A. Ulatowski, Richard J. Traystman, Risto A. Kauppinen

Research output: Contribution to journalArticlepeer-review

Abstract

The hypothesis was tested that hypoperfused brain regions, such as the ischemic penumbra, are detectable by reductions in absolute transverse relaxation time constant (T2) using magnetic resonance imaging (MRI). To accomplish this, temporal evolution of T2 was measured in several models of hypoperfusion and focal cerebral ischemia in the rat at 9.4 T. Occurrence of acute ischemia was determined through the absolute diffusion constant D(av) = (1/3)TraceD̄, while perfusion was assessed by dynamic contrast imaging. Three types of regions at risk of infarction could be distinguished: (1) areas with reduced T2 (4% to 15%, all figures relative to contralateral hemisphere) and normal D(av), corresponding to hypoperfusion without ischemia; (2) areas with both reduced T2 (4% to 12%) and D(av) (22% to 49%), corresponding to early hypoperfusion with ischemia; (3) areas with increased T2 (2% to 9%) and reduced D(av) (28% to 45%), corresponding to irreversible ischemia. In the first two groups, perfusion-deficient regions detected by bolus tracking were similar to those with initially reduced T2. In the third group, bolus tracking showed barely detectable arrival of the tracer in the region where D(av) was reduced. We conclude that T2 reduction in acute ischemia can unambiguously identify regions at risk and potentially discriminate between reversible and irreversible hypoperfusion and ischemia.

Original languageEnglish (US)
Pages (from-to)911-920
Number of pages10
JournalJournal of Cerebral Blood Flow and Metabolism
Volume18
Issue number8
DOIs
StatePublished - Aug 1998

Keywords

  • Acute stroke
  • Bolus tracking
  • Brain
  • Diffusion
  • Ischemia
  • MRI
  • Perfusion imaging
  • Relaxation
  • Spin-spin relaxation time

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine

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