US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid artery US duplex Doppler in the screening of patients at high risk for cerebral aneurysm. US Duplex Doppler Transcranial There is no relevant literature to support the use of TCD in the screening of patients at high risk for cerebral aneurysm. Variant 6: Known high-flow vascular malformation (AVM/AVF). Surveillance monitoring. Intracranial high-flow vascular malformations include arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs). Both lesions are defined by an abnormal connection between the relatively high-pressure arterial system and the low-pressure venous system resulting in a high-flow shunting of blood. AVMs are direct connections of artery to vein via abnormal dilated vascular channels without normal intermediary capillary bed. The abnormal dilated vascular channels are known as the nidus [74]. Although the true incidence of brain AVM is unknown, asymptomatic prevalence on MRI is estimated at 0.05% [74,75]. Between 10% and 20% of patients with hereditary hemorrhagic telangiectasia will have at least one AVM during their lifetime [74,76]. CVD-Aneurysm, Vascular Malformation, and SAH Symptomatic brain AVMs present most commonly with hemorrhage or epilepsy [74]. The annual rupture risk of a brain AVM is 1.3% for previously unruptured AVM and up to 4.8% for previously ruptured lesions [74,77]. Imaging findings associated with higher hemorrhage risk include intranidal aneurysm, deep venous drainage, deep location, or venous outflow obstruction [74,78]. Treatment for AVMs include surgical resection, endovascular embolization, stereotactic radiosurgery, or medical management.
Cerebrovascular Diseases Aneurysm Vascular Malformation and Subarachnoid Hemorrhage PCAs. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid artery US duplex Doppler in the screening of patients at high risk for cerebral aneurysm. US Duplex Doppler Transcranial There is no relevant literature to support the use of TCD in the screening of patients at high risk for cerebral aneurysm. Variant 6: Known high-flow vascular malformation (AVM/AVF). Surveillance monitoring. Intracranial high-flow vascular malformations include arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs). Both lesions are defined by an abnormal connection between the relatively high-pressure arterial system and the low-pressure venous system resulting in a high-flow shunting of blood. AVMs are direct connections of artery to vein via abnormal dilated vascular channels without normal intermediary capillary bed. The abnormal dilated vascular channels are known as the nidus [74]. Although the true incidence of brain AVM is unknown, asymptomatic prevalence on MRI is estimated at 0.05% [74,75]. Between 10% and 20% of patients with hereditary hemorrhagic telangiectasia will have at least one AVM during their lifetime [74,76]. CVD-Aneurysm, Vascular Malformation, and SAH Symptomatic brain AVMs present most commonly with hemorrhage or epilepsy [74]. The annual rupture risk of a brain AVM is 1.3% for previously unruptured AVM and up to 4.8% for previously ruptured lesions [74,77]. Imaging findings associated with higher hemorrhage risk include intranidal aneurysm, deep venous drainage, deep location, or venous outflow obstruction [74,78]. Treatment for AVMs include surgical resection, endovascular embolization, stereotactic radiosurgery, or medical management.