MAGNETIC RESONANCE ANGIOGRAPHY OF THE HEAD and NECK

Abstract

MRA is expected to have its place between the traditional vascular imaging modalities, i.e. Doppler ultrasound and conventional angiography..

Duplex sonography is currently the non-invasive technique of choice for helping and grading diseases involving the carotid arteries.

However poppler ultrasound has several short comings including limited field of view, alteration of velocity ratios affect the diagnosis, as well as its high dependence on operator skills and it has a lack of standard images acceptable by the surgeons.

MRA provides the low-risk, non-invasive advantages of Doppler; while permitting visualization of vascular structures with format resolution comparable to conventional angiography.

The most common MRA technique used is 2D time of flight technique (TOF), which is also useful when only one brief sequence is practically feasible for carotid vessels. 3D TOF has high SNR and short echo timewhich makej it somewhat - ---=....-=:.:...::::.:::.:::::=--'---- . more resistant to signal loss due to complex flow at and distal to stenosis. However 3D TOF used to cover a small segment of vessels which can be determined after screening by 2D TOF.