Arterial spin labeling MRI to measure peak-exercise calf muscle perfusion reproducibly discriminates peripheral arterial

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Arterial spin labeling MRI to measure peak-exercise calf muscle perfusion reproducibly discriminates peripheral arterial disease from normal Amy M West*, Craig H Meyer, Frederick H Epstein, Jennifer R Hunter, Joseph M DiMaria, John M Christopher, Christopher M Kramer From 2011 SCMR/Euro CMR Joint Scientific Sessions Nice, France. 3-6 February 2011 Objective We hypothesized that arterial spin labeling (ASL) using MRI at 3 Tesla would be a reliable technique for measuring peak exercise calf muscle blood flow in both normal volunteers and patients with PAD and will discriminate between these groups.

Table 1 Peak Calf Muscle Perfusion in NL and PAD NL (n=15)

NL, matched exercise time (n=5)

PAD (n=15)

Exercise time, sec

631±388*

240±0

214±110

Peak perfusion, mL/min-100g

77±23*

84±25*

48±16

* p < 0.01 vs PAD

Background Prior work demonstrated the utility of first-pass gadolinium-enhanced calf muscle perfusion MRI in patients with peripheral arterial disease (PAD). However patients with PAD often have advanced renal disease which prohibits the use of gadolinium-based contrast agents due to the concern for nephrogenic systemic fibrosis. ASL for quantification of calf muscle blood flow could provide a non-contrast alternative in advanced renal disease.

processing relative blood flow images were used to measure perfusion with a region of interest in the calf muscle area with the greatest signal intensity.

Results Peak exercise calf perfusion (mean±SD) of 15 NL (age 54 ±9) was significantly higher than in 15 PAD (age 64±5, ABI 0.70±0.14), see Table 1. Five NL performed exercise matched to PAD (240s) and demonstrated significantly

Methods PAD patients had symptomatic claudication and an ankle brachial index (ABI) 0.4-0.9. Age-matched normal subjects (NL) had no PAD risk factors. All subjects performed supine plantar flexion exercise using a pedal ergometer until exhaustion or limiting symptoms and were immediately imaged with a flexible calf coil in a Siemens 3T Trio. At end-exercise, 15 averaged arterial spin labeled images were acquired using a pulsed ASL pulse sequence with single-shot echo-planar imaging readouts. Spin labeling was performed using the proximal inversion with control for off-resonance effects (PICORE) technique and the Q2TIPS modification to minimize errors resulting from transit delay. Siemens postUniversity of Virginia, Charlottesville, VA, USA

Figure 1 Peak Calf Muscle Perfusion in NL (arrow)

© 2011 West et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

West et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):P347 http://jcmr-online.com/content/13/S1/P347

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higher perfusion (Table 1). Repeat testing on different days was performed in a group of 12 subjects (5 NL, 7 PA