Purpose
To assess image quality and diagnostic performance of non-contrast enhanced MR angiography (NCE-MRA) using flow-sensitive dephasing (FSD) prepared steady-state free precession (SSFP) for the foot arteries in patients with diabetes.
Materials and Methods
This prospective study was approved by institutional review board and informed consent was obtained from all subjects. Thirty-two healthy volunteers and 38 diabetic patients who had been scheduled for lower extremity contrast-enhanced MRA (CE-MRA) were recruited for the NCE-MRA study on a 1.5T MR system. Image quality and diagnostic accuracy of NCE-MRA for detecting significant arterial stenosis (≥50%) were assessed by two independent reviewers using CE-MRA as reference standard. The difference of the percentage of diagnostic arterial segments on NCE-MRA between healthy volunteers and diabetic patient was evaluated using McNemar test and Generalized Estimating Equation (GEE) for correlated data. Signal-to-noise ratio (SNR) and artery-to-muscle contrast-to-noise ratio (CNR) of pedal arteries were measured and compared between the two MRA techniques using paired t-test.
Results
All subjects successfully underwent NCE-MRA of the foot. NCE-MRA yielded a high percentage of diagnostic arterial segments obtained in both healthy volunteers (303/320=95%) and patients (341/370=92%) and there was no difference in the percentage between the two populations (p=0.195). In patients, the average SNR, and CNR on NCE-MRA was higher than those on CE-MRA (90.7± 38.1 vs. 81.7± 34.7, p=0.023, and 85.2 ± 33.2 vs. 76.6 ± 33.5, p=0.013, respectively.). The average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of NCE-MRA were 35/40=88%, 107/115=93%, 35/43=81%, 107/112=96%, and 142/155=92%, respectively. Interobserver agreement between the two readers for diagnostic accuracy was good (k = 0.83).
Conclusion
NCE-MRA using FSD-prepared SSFP allows clear depiction of the foot arterial tree and accurate detection of significant arterial stenosis. The technique has the potential to be a safe and reliable screening tool for the assessment of foot arteries in diabetic patients without using gadolinium-based contrast agent.