Abstract 2762: Reproducibility and Reliability of Atherosclerotic Plaque Imaging in Peripheral Arterial Disease: Implications for Clinical Trials
Introduction: Measurement of atherosclerotic plaque volume (APV) in the superficial femoral artery (SFA) by magnetic resonance imaging (MRI) may allow reduced sample sizes for studies of serial changes in APV.
Methods: 17 patients (age 63±10) with moderate peripheral arterial disease (PAD) (ankle brachial index 0.72±0.11) were studied in a 1.5T MRI scanner. A custom-built, linear surface coil was placed over the SFA. Contiguous 3mm slices were imaged with a multi-slice fast spin echo sequence with fat and blood presaturation (Figure 1⇓). APV of SFA was contoured by 2 independent observers. 9 subjects had a repeat study (mean 24 days later). Intraobserver/interobserver reproducibility and test-retest reliability were determined by intraclass correlation. Sample size estimates were based on test-retest data, expected standard deviation, paired t-test, and alpha 0.05
Results: 19 arteries in 17 patients were studied (length 17.1±5.2 cm) in 13.1±2.7 min. Mean APV was 7.27±3.73cm3. Intraclass correlation coefficients were 0.997, 0.993, and 0.996 for intraobserver, interobserver and test-retest reliability. Table 1⇓ shows sample size estimates.
Conclusion: High resolution MRI measurement of high volume atherosclerotic plaque in the SFA in PAD is feasible and highly reproducible. This approach could reduce sample sizes needed for studies using changes in APV as a surrogate end-point.