Measurement of skeletal muscle perfusion during postischemic reactive hyperemia using contrast-enhanced MRI with a step-input function.
The regional distribution of skeletal muscle blood flow was measured during postischemic reactive hyperemia using Gd-DTPA contrast-enhanced (CE) MRI. The release of an occlusive thigh cuff was used to deliver a step-input of contrast concentration that was coincident with the onset of reactive hyperemia. A first-order tracer kinetic equation was used to estimate the unidirectional influx constant, Ki (ml/100 g/min), and the distribution volume of Gd-DTPA in the tissue, v(e), from T1-weighted images acquired with saturation recovery (SR) steady-state free precession (SSFP) and spoiled gradient-echo (SPGR) protocols. The capillary permeability surface (PS) area increased significantly during reactive hyperemia, which facilitated rapid extraction of Gd-DTPA during the first pass. Regional muscle group studies from 11 normal volunteers yielded blood flow (Ki) values of 108.3 +/- 34.1 ml/100 g/min in the gastrocnemius, 184.3 +/- 41.3 ml/100 g/min in the soleus, and 122.4 +/- 34.4 ml/100 g/min in the tibialis anterior. The distribution volumes (v(e)) in the corresponding muscle groups were respectively 8.3% +/- 2.1%, 9.3% +/- 1.9%, and 7.9% +/- 1.8% from the kinetic model, and 8.8% +/- 2.4%, 9.1% +/- 1.9%, and 7.2% +/- 1.4% from tissue relaxometry studies. Bulk blood flow studies in the same volunteers using phase-contrast velocimetry (popliteal artery) yielded significantly lower flow values, but with a correlation coefficient R2 = 0.62 and P = 0.004.
Thompson
Richard B
RB
Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA. richard.thompson@ualberta.ca
Aviles
Ronnier J
RJ
Faranesh
Anthony Z
AZ
Raman
Venkatesh K
VK
Wright
Victor
V
Balaban
Robert S
RS
McVeigh
Elliot R
ER
Lederman
Robert J
RJ
D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology; D003287:Contrast Media / Q000493:pharmacokinetics*; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology*; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D016018:Least-Squares Analysis; D007866:Leg / Q000098:blood supply*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D018482:Muscle, Skeletal / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology
D003287:Contrast Media; D019786:Gadolinium DTPA