Effect of bolus length of intraarterial injections on contrast-enhanced MR-angiography in patients

Purpose To perform MR‐guided interventions, repetitive injections of contrast agent in the arterial system are necessary. By reducing the intraarterial bolus length during image acquisition and consecutively reducing the gadolinium‐chelate–based contrast agent dose, we focus on a comparable vascular depiction. The tradeoff in reducing bolus length is vascular depiction. Materials and Methods Intraarterial gadolinium‐chelate injection was performed to depict the femoropopliteal artery and infrapopliteal arteries in six patients. Six measurements with a bolus length of 20% to 100% of the total acquisition time were performed (three‐dimensional [3D] Turbo‐fast low‐angle shot (FLASH) sequence, 1.5 T). Contrast‐to‐noise ratio (CNR) was determined and a consensus reading of vascular depiction was performed. Results CNR values comparable 100% of bolus length were obtained for the femoropopliteal artery at ≥40% and for the infrapopliteal arteries at ≥60%. Qualitative analysis demonstrated that a bolus length of ≥60% is necessary to reveal a good diagnostic vascular depiction. Conclusion Quantitatively, a reduction of intraarterial gadolinium‐chelate dosage in patients is possible down to 40% in the femoropopliteal artery and to 60% in the infrapopliteal arteries to acquire a CNR comparable to 100% of bolus length. Qualitatively, however, the bolus length can only be reduced down to 60% for both level to produce a good diagnostic vascular depiction and is, for diagnostic purposes, the limiting factor. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.