CT Angiography of Cerebral Arteries (PDF)

Computed Tomography  COMPUTED TOMOGRAPHY  CT angiography of the cerebral arteries (protocol)  :BY AHMED JASEM ABASS  MSCof Medical Imaging CT angiography of the cerebral arteries  CT angiography of the cerebral arteries (also known as a CTA carotids or an arc...

Computed Tomography  COMPUTED TOMOGRAPHY  CT angiography of the cerebral arteries (protocol)  :BY AHMED JASEM ABASS  MSCof Medical Imaging CT angiography of the cerebral arteries  CT angiography of the cerebral arteries (also known as a CTA carotids or an arch to vertex angiogram) is a noninvasive technique allows visualization of the internal and external carotid arteries and vertebral arteries.  Computerized tomographic angiography is used to visualize blood vessels that have been opacified by CM.  This include:  CIRCLE OF WILLIS.  CAROTID ARTERIES. CT angiography of the cerebral arteries  ANGIOGRAPHY OF HEAD  Done for the study of CIRCLE OF WILLIS  Also known as CEREBRAL ANGIOGRAPHY  ANGIOGRAPHY OF NECK  Done for the study of CAROTID ARTERIES.  Also known as CAROTID ARANGIOGRAPHY Preparation:  NPO 3-4 hrs before the exam.  Not severly allergic or asthmatic  Recent Renal function test(RFT) must be normal;  Explain procedure  Signed consent form  Sedation if needed CT angiography of the cerebral arteries  Extracranial circulation  Atherosclerosis, Aneurysms, dissection  Intracranial circulation  Intracranial aneurysms, Arteriovenous malformations CT angiography of the cerebral arteries  When scanning cervicocranial arteries, the patient is in the supine position.  The right antecubital vein is the preferred site CT angiography of the cerebral arteries  Arterial Supply of the Brain  Blood supply to the brain is derived from two arteries:  (1) The internal carotid artery and  (2) The vertebral artery.  These arteries and their branches arise in pairs that supply blood to both sides of the brain.  The major arteries supplying the cerebrum (basilar artery and internal carotid) get interconnected to one another at the base of the brain to form a six-sided polygon of arteries called circular arteriosus.  It formed around the interpeduncular fossa. CT angiography of the cerebral arteries Indcation Contraindcation  Aneurysm  Pregnancy  Narrowing of arteries in the brain  Allergic to Contrast  Abnormal blood vessels. media.  Narrowing or blockage of  Weak kidney Function. carotid arteries.  Stenosis  Unstable vital signs  To determine future risk of stroke  Stricture of the Carotid arteries. Summary of technique…  patient position  supine with their arms by their side  Scout mid-chest to vertex  scan extent aortic arch to vertex  scan direction caudocranial  contrast injection considerations 1. monitoring slice (region of interest) : descending aorta 2. Threshold :150 HU 3. injection : 50-75 ml of non-ionic iodinated contrast with a 50 ml saline 4. scan delay: minimal scan delay 5. respiration phase suspended PATIENT POSITIONING: Monitoring slice (region of interest) : descending aorta e.g. bolus tracking technique showing the region of interest centred within the main pulmonary artery (MPA), with the threshold attenuation level for triggering set at 100 Hounsfield Units Post-processing…  CTA images are usually presented as axial and coronal and/or sagittal multiplanar reformat of a variety of thicknesses.  Additional post-processing techniques include:  maximum intensity projection MIP displays pixels with higher CT value  curved planar reformats: delineates the entire course of the vessel and can be used when the vessel is tortuous. CT angiography of a patient with residual aneurysm in the left posterior communicating artery (PCOM) Aneurysm in anterior cerebral artery… Thank You