Evaluation of cuff-induced ischemia in the lower extremity by magnetic resonance oximetry.

Abstract

OBJECTIVES:

The aim of this study was to evaluate vascular function in the lower extremities by making direct time-course measurement of oxygen saturation in the femoral/popliteal arteries and veins during cuff-induced reactive hyperemia with magnetic resonance imaging-based oximetry.

BACKGROUND:

Magnetic resonance imaging-based oximetry is a new calibration-free technique taking advantage of the paramagnetic nature of blood that depends on the volume fraction of deoxyhemoglobin in red blood cells.

METHODS:

We compared post-occlusive blood oxygenation time-course of femoral/popliteal vessels in: 1) young healthy subjects (YH) (n = 10; mean ankle-brachial index [ABI] 1.0 +/- 0.1, mean age 30 +/- 7 years); 2) peripheral arterial disease (PAD) patients (n = 12; mean ABI 0.6 +/- 0.1, mean age 71 +/- 9 years); and 3) age-matched healthy control subjects (AHC) (n = 8; mean ABI 1.1 +/- 0.1, mean age 68 +/- 9 years). Blood oxygenation was quantified at 3.0-T field strength with a field mapping pulse sequence yielding the magnetic susceptibility difference between blood in the vessels and surrounding muscle tissue from which the intravascular blood oxygen saturation is computed as %HbO(2).

RESULTS:

Significantly longer washout time (42 +/- 16 s vs. 14 +/- 4 s; p < 0.0001) and lower upslope (0.60 +/- 0.20 %HbO(2)/s vs. 1.32 +/- 0.41 %HbO(2)/s; p = 0.0008) were observed for PAD patients compared with healthy subjects (YH and AHC combined). Furthermore, greater overshoot was observed in YH than in AHC (21 +/- 8 %HbO(2) vs. 10 +/- 5 %HbO(2); p = 0.0116).

CONCLUSIONS:

Post-occlusive transient changes in venous blood oxygenation might provide a new measure of vascular competence, which was found to be reduced in subjects with abnormal ABI, manifesting in prolonged recovery during the early phase of hyperemia.

• Authors: Michael C Langham, Thomas F Floyd, Emile R Mohler 3rd, Jeremy F Magland, Felix W Wehrli
• Journal: Journal of the American College of Cardiology (J Am Coll Cardiol) Vol. 55 Issue 6 Pg. 598-606 (Feb 09 2010) ISSN: 1558-3597 [Electronic] United States
• PMID: 20152564 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Topics

• Adult
• Aged
• Aged, 80 and over
• Female
• Femoral Artery
• Femoral Vein
• Humans
• Ischemia (physiopathology)
• Lower Extremity (blood supply)
• Magnetic Resonance Imaging (methods)
• Male
• Middle Aged
• Oximetry (methods)
• Popliteal Artery
• Popliteal Vein