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(Stroke. 2003;34:2536.)
© 2003 American Heart Association, Inc.

Controversies in Stroke

Ischemic Penumbra: MRI or PET

From the Department of Neurology (S.M.D.), Royal Melbourne Hospital and University of Melbourne, and The National Stroke Research Institute (G.A.D.), Austin and Repatriation Medical Centre and University of Melbourne, Australia.

Correspondence to Prof Stephen M. Davis, Department of Neurology, Royal Melbourne Hospital, Parkville Victoria 3050, Australia. E-mail stephen.davis@mh.org.au

Key Words: magnetic resonance imaging • penumbra • therapy • tomography, emission computed

An extract of the first 250 words of the full text is provided, because this article has no abstract.

" ... the outcome of incomplete cerebral ischemia is of particular interest. ... one hopes it will become possible to conduct treatment and to evaluate prognosis in the acute stroke patient by reproducible repeatable measurement in man."

Astrup et al¹

Why is the penumbra so important? In the 1970s it gave us the first insight into the prolonged nature of tissue survival after stroke. In the 1990s its importance as a target for therapy was confirmed with the introduction of tPA as the first treatment aimed at rapid reperfusion and salvage of critically hypoperfused brain.

The protagonists have nicely positioned the current status of in vivo measurement of the penumbra. On one hand we have PET, which has provided such important biological insights (particularly quantitative) into penumbral characteristics such as blood flow and metabolism, while on the other we have the pragmatic advantages of MRI. PET and MRI provide complementary information about a phenomenon that can be defined in more than one way. Both techniques have contributed enormously to our current understanding of tissue viability.

We are, therefore, of the view that there is no gold standard for human penumbral measurement. Indeed, both PET and MRI concepts continue to evolve. For example, as outlined by Heiss, we have moved from the original ¹⁵O techniques through to ¹¹C flumazenil and ¹⁸FMISO. Using MRI, the mismatch concept (hypoperfusion volume > DWI lesion core) has been modified with the recognition that a portion of hypoperfused brain reflects benign oligemia and that the DWI . . . [Full Text of this Article]