Vein graft surveillance with scanhead tracking duplex ultrasound imaging: A preliminary report

A severe arterial occlusion in the leg usually is bypassed by implanting a saphenous vein harvested from the limb. Once implanted, the vein functions well but over time may develop stenoses that may lead to occlusion. In orde r to detect and correct the stenoses that may lead to graft failure, freque nt surveillance of the vein graft is required. A new ultrasound imaging met hod was developed to display the panoramic view of the vein graft in combin ation with its blood flow velocity waveform for surveillance. The panoramic view is the projection (ray-casting) image of multiple B-mode images with sequential longitudinal view of the vein graft. The velocity waveform also is recorded along the vessel with pulsed Doppler ultrasound. The acquired i mages and waveforms from the ultrasound scanner are registered individually in three-dimensional space with an electromagnet-based position and orient ation sensor located on the scanhead, A prominent point on the scar from th e surgery is used as the fiducial mark for spatial registration, so that th e same lesion in the vein graft can be tracked automatically at each visit for retrospective study. (C) 1998 World Federation for Ultrasound in Medici ne & Biology.