3D nongadolinium‐enhanced ECG‐gated MRA of the distal lower extremities: Preliminary clinical experience

Abstract

Purpose To report our initial experience implementing a noncontrast‐enhanced electrocardiograph (ECG) gated fast spin echo magnetic resonance angiography (MRA) technique for assessment of the calf arteries. Materials and Methods Noncontrast MRA images of 36 clinical patients examined over a 6‐month period were evaluated by two radiologists for length and degree of stenosis of arterial segments. Diagnostic confidence in the technique was also recorded. The reference standard was a consensus reading by both radiologists using the noncontrast technique combined with two gadolinium‐enhanced techniques: bolus‐chase and time‐resolved imaging. Results For stenosis evaluation the noncontrast technique demonstrated accuracy 79.4% (1083/1364), sensitivity 85.4% (437/512), and specificity 75.8% (646/852). The sequence demonstrated high negative predictive value (92.3%, 646/700). The technique had serious artifacts leading to poor diagnostic confidence in 17 patients (47.2%). These included motion (n = 7) and artifacts specific to the sequence, including inaccurate trigger delays (n = 5), linear artifact (n = 7), and vessel blurring (n = 5). When only patients in whom there was satisfactory diagnostic confidence were considered, accuracy, sensitivity, and negative predictive value were 92.2% (661/717), 92.4% (158/171), and 97.5% (503/516), respectively. Conclusion Our results indicate that when technically successful, noncontrast‐enhanced MRA using ECG‐gated fast spin echo can provide accurate imaging of the calf and pedal arteries. However, further development and optimization are needed to improve the robustness of the technique. J. Magn. Reson. Imaging 2008;28:181–189.