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  • Print publication year: 2003
  • Online publication date: August 2009

7 - MR angiography of the head and neck: basic principles and clinical applications

Summary

This chapter opens with a discussion on the basic principles of Magnetic Resonance Angiogram (MRA), including time of flight and phase contrast techniques. It introduces the use of paramagnetic contrast agents for MRA. The advantages and pitfalls of MRA as compared with duplex sonography (DUS) and X-ray angiography (XRA) are discussed. MR uses a combination of magnetic fields and radiofrequency energy to produce images. MRI is highly accurate at measuring the carotid wall area and T2-weighted images can discriminate between the fibrous cap and lipid core of a plaque. The combination of MRI and MRA is an accurate non-invasive means for the detection of carotid and vertebral dissections. MRI depicts the nidus of a vascular malformation. MRA is reliable for detecting stenoses and occlusions involving the vertebrobasilar system. For the intracranial circulation, MRA is well accepted for imaging of the dural sinuses and larger intracranial veins.