Does the mismatch match the penumbra? Magnetic resonance imaging and positron emission tomography in early ischemic stroke.
OBJECTIVE
In ischemic stroke, diffusion-weighted (DW) and perfusion-weighted (PW) magnet resonance imaging (MRI) is used to define the mismatch as the therapeutic target. With positron emission tomography (PET), we characterized the metabolic patterns of tissue compartments identified by MRI and compared the volumes of mismatch to those of PET-defined penumbra.


METHODS
In 6 acute (median, 5.2 hours) and 7 chronic (median, 10 days) stroke patients in whom a mismatch was defined by PW/DW MRI, PET was performed (median, 120-minute delay). Cerebral blood flow (CBF), oxygen metabolism (CMRO2), and oxygen extraction fraction (OEF) was determined in the areas of DWI lesion, mismatch, and oligemia. Then, the mismatch volume was compared with the volume of penumbra.


RESULTS
DWI lesions showed impaired tissue integrity (low CMRO2 and low OEF). Mismatch areas were viable (normal CMRO2) but showed largely varying OEF. Oligemic areas had metabolic patterns comparable to normal tissue. A mismatch volume was found in all 13 patients. However, only 8 of 13 had a corresponding penumbra volume that covered only a part of the mismatch.


CONCLUSIONS
Our comparative PET/MRI study confirmed the current pathophysiological hypothesis for the DWI lesion and for the oligemic areas. However, the mismatch area did not reliably detect elevated OEF and overestimated the penumbra defined by PET.
Sobesky
Jan
J
Max Planck Institute for Neurological Research, Cologne, Germany. j.sobesky@pet.mpin-koeln.mpg.de
Zaro Weber
Olivier
O
Lehnhardt
Fritz-Georg
FG
Hesselmann
Volker
V
Neveling
Michael
M
Jacobs
Andreas
A
Heiss
Wolf-Dieter
WD
D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D020521:Stroke / Q000175:diagnosis* / Q000000981:diagnostic imaging