Projection MR imaging of peripheral arterial calcifications

Both CT and MR angiography are accurate for the evaluation of luminal abnormalities in peripheral arterial disease (PAD). However, only CT (requiring exposure to potentially hazardous ionizing radiation) provides a reliable means to detect vascular calcifications. In this study, we demonstrate the feasibility of detecting peripheral arterial calcifications with MRI.

The institutional investigational review board approved the study. Seven patients with PAD and iliofemoral arterial calcifications shown by prior CT angiography (CTA) were studied. The imaging techniques included: 1) dual-echo three-dimensional (3D) gradient recalled echo (GRE) pulse sequence using flow compensation and in-phase echo times (TE); and 2) prototype version of 3D point-wise encoding time reduction with radial acquisition (PETRA), which enables imaging with an ultra-short TE.

With both techniques after grayscale inversion, vascular calcifications appeared bright, as did cortical bone, and were readily distinguished from the vessel lumen and surrounding soft tissues. The location and conformation of the calcifications corresponded with CT. The second echo GRE provided the highest contrast-to-noise ratios; whereas PETRA was best suited for the creation of thick projection images.

In this pilot study, MRI was able to detect vascular calcifications. Projection imaging using PETRA provided a similar appearance to, and allowed direct comparison with, CT.