Simultaneous measurement of perfusion and oxygenation changes using a multiple gradient-echo sequence: application to human muscle study.
We have developed a magnetic resonance imaging (MRI) technique based on a multiple gradient-echo sequence designed to probe perfusion and oxygenation simultaneously within skeletal muscle. Processing of the images acquired at successive echo times (TEs) generates two functional maps: one of the signal intensity (SI) extrapolated to zero echo time, which is sensitive to perfusion; and a second one of R2*, which reflects oxygenation. An advantage of the processing procedure lies in the selection of tissue of interest through the profile of T2* decay, leading to automatic rejection of pixels containing small vessels. This allows a more specific assessment of tissue perfusion and oxygenation. This technique was demonstrated successfully during post-ischemic reactive hyperemia in human calf. A perfusion peak of 123 mL x 100 g(-)1 x min(-1) was measured immediately after ischemia, whereas R2* value showed an 11.5% decrease at the same time, essentially reflecting blood oxygenation changes. Differences in the time courses of reperfusion and re-oxygenation were observed, oxygenation presenting a slower recovery. The mechanisms responsible for such a differential dynamic response are discussed.
Lebon
V
V
Service Hospitalier Frédéric Joliot, CEA, Orsay, France.
Carlier
P G
PG
Brillault-Salvat
C
C
Leroy-Willig
A
A
D000328:Adult; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D006940:Hyperemia / Q000378:metabolism / Q000503:physiopathology; D007511:Ischemia / Q000378:metabolism / Q000503:physiopathology; D008833:Microcirculation / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010991:Plethysmography
D010100:Oxygen