Noncontrast-enhanced peripheral MRA: technical optimization of flow-spoiled fresh blood imaging for screening peripheral arterial diseases.

Flow-spoiled fresh blood imaging, a noncontrast peripheral MR angiography technique, allows the depiction of the entire tree of peripheral arteries by utilizing the signal difference between systolic- and diastolic-triggered data. The image quality of the technique relies on selecting the right triggering delay times and flow-dependent read-out spoiler gradient pulses. ECG triggering delays were verified using manual subtraction and automated software. The read-out spoiler gradients pulses were optimized on volunteers before utilizing the flow-spoiled fresh blood imaging technique to screen for peripheral arterial disease. Thirteen consecutive patients with suspected peripheral arterial disease underwent both flow-spoiled fresh blood imaging and 16-detector-row computed tomography angiography examinations. A total of 23 segments were evaluated in the arterial vascular system. Using computed tomography angiography as the reference standard, 56 diseased segments were detected with 22 nonsignificant stenoses (<50%) and 34 significant stenoses, 15 of which were totally occluded. Flow-spoiled fresh blood imaging had a sensitivity of 97%, a specificity of 96%, an accuracy of 96%, a positive predictive value of 88%, and a negative predictive value of 99%. With such a high negative predictive value, flow-spoiled fresh blood imaging has the potential to become the safest noninvasive screening tool for peripheral arterial disease, especially for patients with impaired renal function.