Peripheral vascular disease

Peripheral vascular disease results from arterial blockages in the extremities. Patients present in one of two categories:

• claudicants who experience pain with exercise
• ischemics who experience continual pain

If left untreated, amputation of the affected limb may be required. Surgical intervention is via an arterial bypass. For such a procedure, it is necessary to locate a suitable distal sight for the bypass, including such factors as patency of the vessel and the run-off from potential bypass sites. Due to extremely slow flows in these areas, X-ray angiography does not always perform well, as the contrast agent has difficulty reaching distal vessels. Magnetic resonance angiography may play a role in these patients as this limitation can be overcome.

Comparisons investigated have been:

• 2-D time-of-flight
• 3-D flow-independent angiography (FIA) - limited SNR, long acquisition time; difficult artery isolation
• 3-D gadolinium-enhanced angiography techniques - excellent SNR and artery isolation; resolution/FOV limited by timing window and multiple scans needed for full coverage

Sample images using 2DTOF (left), 3-D FIA (middle) and 3-D Gd-enhanced (right) techniques at the level of the popliteal trifurcation.

The 3-D nature of this FIA data set of the foot allows for projections to be made at different angles to help resolve the 3-D structure of vessels (courtesy of Jean Brittain, Stanford University).