Technical note: postgadolinium two-dimensional time-of-flight MR angiography of the foot

The purpose of this study was to determine the ability of postgadolinium time-of-flight (TOF) MR angiography to image the foot of patients compared to conventional TOF MR angiography.

Six feet in five patients were included in this prospective study. Standard two-dimensional axial TOF sequences of the lower extremities, followed by three-dimensional (3D) contrast-enhanced moving-table images of the aorta to the foot during the intravenous bolus administration of gadolinium, were obtained in all patients. Two-dimensional axial respiratory-compensated TOF sequences were then obtained over the foot. Axial images and maximum intensity projections (MIP) reconstructions were evaluated by two blinded radiologists and images rated with respect to overall image quality, large-vessel and small-vessel visualization, degree of venous overlap, and extent of vessel stenosis.

The 2D postgadolinium TOF technique resulted in an improvement in all areas of image quality compared with the noncontrast acquisition method, with very good interobserver agreement (kappa 0.67). Postcontrast images provided superior vessel visualization ( p=0.024, Wilcoxon signed rank test), with minimal artifact (84% with none, kappa 1.0), and excellent agreement on grading of dorsalis pedis stenosis (kappa 0.78). Vessel-to-background signal intensity ratio was doubled compared to the standard technique (mean 19.5, SD 6.5 versus 8.8, SD 4.5; p=0.016).

Postgadolinium TOF MR angiography of the foot demonstrates significantly improved image quality over noncontrast techniques.