Peripheral moving‐table contrast‐enhanced magnetic resonance angiography (CE‐MRA) using a prototype 18‐channel peripheral vascular coil and scanning parameters optimized to the patient's individual hemodynamics

Abstract

To demonstrate that with a priori determination of individual patient hemodynamics, peripheral contrast-enhanced magnetic resonance angiography (pCE-MRA) can be customized to maximize signal-to noise ratio (SNR) and avoid venous enhancement. Using a 1.5T MRI scanner and prototype 18-channel peripheral vascular (PV) coil designed for highly accelerated parallel imaging, geometry (g)-factor maps were determined. SNR-maximized protocols considering the two-dimensional sensitivity encoding (2D SENSE) factor, TE, TR, bandwidth (BW), and flip angle (FA) were precalculated and stored. For each exam, a small aortic timing bolus was performed, followed by dynamic three-dimensional (3D)-MRA of the calf. Using this information, the aorta to pedal artery and calf arteriovenous transit times were measured. This enabled estimation of the maximum upper and middle station acquisition duration to allow lower station acquisition to begin prior to venous arrival. The appropriately succinct SNR-optimized protocol for each station was selected and moving-table pCE-MRA was performed using thigh venous compression and high-relaxivity contrast material. The protocol was successfully applied in 15 patients and all imaging demonstrated good SNR without diagnosis-hindering venous enhancement. By knowing each patient's venous enhancement kinetics, scan parameters can be optimized to utilize maximum possible acquisition time. Some time is added for the timing scans, but in return time-resolved calf CE-MRA, maximized SNR, and decreased risk of venous enhancement are gained.