Original Research MRA Contrast Bolus Timing With Ultrasound Bubbles

The purpose of this study was to determine the feasibility of using an ultrasound contrast agent test bolus to deter-mine optimum bolus timing for three-dimensional (3D) gadolinium (Gd)-enhanced magnetic resonance angiogra-phy (MRA). Small test doses of ultrasound contrast agent (0.3 ml Optison) were injected intravenously followed imme-diately by a 20 ml saline flush. Arrival of the contrast agent was detected by spectral Doppler ultrasound (US). This technique was implemented in patients undergoing periph-eral vascular MRA and carotid MRA. Arrival of the US contrast agent test bolus was readily detected by the change in amplitude of the Doppler spectrum and by a huge increase in the audio signal amplitude. This contrast travel time measurement accurately guided bolus timing for 3D Gd MRA. Bolus timing for 3D contrast-enhanced MRA can be performed using US, thereby eliminating the problems and MR scanner time required for injecting a test bolus o