Diagnosis of intracranial occlusive vascular disease and evaluation of extracranial-intracranial (EC/IC) arterial bypass using three-dimensional magnetic resonance angiography

The three-dimensional time-of-flight (TOF) magnetic resonance angiograms (MRA) were studied to evaluate its accuracy in the assessment of the intracranial carotid occlusive lesions, collateral circulation and also the patency of extracranial-intracranial (EC/IC) arterial bypass surgery. All occlusive lesions of the intracranial major arteries seen in conventional angiograms were revealed clearly with MRA. However MRA had its practical limitation in the evaluation of the leptomeningeal anastomosis (collateral circulation) probably due to the deterioration of contrast in its slow flow and saturation effect of the magnetization. In addition to that, MRA often exaggerated the severity of the stenotic lesions, mostly in severe cases. The postoperative state of collateral flow and the patency of EC/IC bypass could be evaluated as properly with MRA as with conventional angiography, although MRA was limited in spatial resolution and evaluation of flow direction. In conclusion, MRA was considered to be a reliable non-invasive modality as a screening examination for the evaluation of the carotid occlusive disease and as the follow-up study of the post-operative patients with EC/IC bypass surgery. (author)