Reproducibility of rest and exercise stress contrast-enhanced calf perfusion magnetic resonance imaging in peripheral arterial disease.
BACKGROUND
The purpose was to determine the reproducibility and utility of rest, exercise, and perfusion reserve (PR) measures by contrast-enhanced (CE) calf perfusion magnetic resonance imaging (MRI) of the calf in normal subjects (NL) and patients with peripheral arterial disease (PAD).


METHODS
Eleven PAD patients with claudication (ankle-brachial index 0.67 ±0.14) and 16 age-matched NL underwent symptom-limited CE-MRI using a pedal ergometer. Tissue perfusion and arterial input were measured at rest and peak exercise after injection of 0.1 mM/kg of gadolinium-diethylnetriamine pentaacetic acid (Gd-DTPA). Tissue function (TF) and arterial input function (AIF) measurements were made from the slope of time-intensity curves in muscle and artery, respectively, and normalized to proton density signal to correct for coil inhomogeneity. Perfusion index (PI) = TF/AIF. Perfusion reserve (PR) = exercise TF/ rest TF. Intraclass correlation coefficient (ICC) was calculated from 11 NL and 10 PAD with repeated MRI on a different day.


RESULTS
Resting TF was low in NL and PAD (mean ± SD 0.25 ± 0.18 vs 0.35 ± 0.71, p = 0.59) but reproducible (ICC 0.76). Exercise TF was higher in NL than PAD (5.5 ± 3.2 vs. 3.4 ± 1.6, p = 0.04). Perfusion reserve was similar between groups and highly variable (28.6 ± 19.8 vs. 42.6 ± 41.0, p = 0.26). Exercise TF and PI were reproducible measures (ICC 0.63 and 0.60, respectively).


CONCLUSIONS
Although rest measures are reproducible, they are quite low, do not distinguish NL from PAD, and lead to variability in perfusion reserve measures. Exercise TF and PI are the most reproducible MRI perfusion measures in PAD for use in clinical trials.
Departments of Medicine and the Cardiovascular Imaging Center, University of Virginia Health System, Charlottesville, VA, USA.
Ronny S
RS
Jiji
Amy W
AW
Pollak
Frederick H
FH
Epstein
Patrick F
PF
Antkowiak
Craig H
CH
Meyer
Arthur L
AL
Weltman
David
D
Lopez
Joseph M
JM
DiMaria
Jennifer R
JR
Hunter
John M
JM
Christopher
Christopher M
CM
Kramer
D000368:Aged; D000369:Aged, 80 and over; D055109:Ankle Brachial Index; D001783:Blood Flow Velocity; D016022:Case-Control Studies; D005080:Exercise Test; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D058729:Peripheral Arterial Disease / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D013997:Time Factors
D019275:Radiopharmaceuticals; D019786:Gadolinium DTPA