Imaging Pearls ❯ Neuroradiology ❯ Intracranial Aneurysms and CTA
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- “The measurement of maximum cerebral blood flow of collateral vessels within the Sylvian fissure is a feasible quantitative collateral assessment at perfusion CT. Maximum cerebral blood flow of collateral vessels was associated with clinical outcome in patients with acute ischemic stroke.”
Acute Stroke: Prognostic Value of Quantitative Collateral Assessment at Perfusion CT
Feina Shi et al.
Radiology 2019; 290:760–768 - “Ischemic penumbra, defined as brain tissue at risk for infarction that remains salvageable after acute ischemic stroke (AIS), is the aim of reperfusion therapy. Collateral circulation in patients with AIS can maintain perfusion and may contribute to prolonged penumbral sustenance. Greater vascular collaterization is associated with better neurologic outcome”
Acute Stroke: Prognostic Value of Quantitative Collateral Assessment at Perfusion CT
Feina Shi et al.
Radiology 2019; 290:760–768 - “Perfusion CT is being applied prior to reperfusion therapy with increasing frequency and may enable quantitative evaluation of hemodynamic status. We hypothesized that perfusion CT-derived blood flow of collateral vessels within the Sylvian fissure may reflect retrograde filling via the leptomeningeal collateral in patients with large artery occlusion of the anterior circulation.”
Acute Stroke: Prognostic Value of Quantitative Collateral Assessment at Perfusion CT
Feina Shi et al.
Radiology 2019; 290:760–768 - Implications for Patient Care
* Identification of good collateral status based on the maximum cerebral blood flow value of collateral vessels derived from perfusion CT is a feasible and reproducible quantitative method for collateral assessment at perfusion CT.
* Maximum cerebral blood flow value of collateral vessels at perfusion CT may help physicians facilitate appropriate patient triage, guide prognosis, and refine the selection of patients eligible for reperfusion in late time windows of acute ischemic stroke.
Acute Stroke: Prognostic Value of Quantitative Collateral Assessment at Perfusion CT
Feina Shi et al.
Radiology 2019; 290:760–768
- “Common carotid artery (CCA) pseudoaneurysms are rare and potentially lethal, and adequate treatment is warranted in order to prevent rupture or neurologic sequelae. The causes of CCA pseudoaneurysm include blunt or penetrating trauma, infection, and vasculitis, as well as iatrogenic and unknown causes. Previously, surgery was the standard treatment for pseudoaneurysm.
Cases of Common Carotid Artery Pseudoaneurysm Treated by Stent Graft Hee Ok Kim et al. Case Reports in Otolaryngology Volume 2012 (2012), Article ID 674827 - “Common carotid artery (CCA) pseudoaneurysm is usually discovered as pulsate neck mass. The neurological deficit due to compression of nerve can also be seen. The intracranial occlusion or intracranial embolus can occur due to thrombus. This may lead to rupture; the results of which can be fatal, so immediate treatment is necessary.”
Cases of Common Carotid Artery Pseudoaneurysm Treated by Stent Graft Hee Ok Kim et al. Case Reports in Otolaryngology Volume 2012 (2012), Article ID 674827
- “ There are multiple suggested causes for the left-sided predominance of venous reflux. Anatomic differences in the course of the brachiocephalic veins may be a factor. The right brachiocephalic vein is more parallel to the ascending aorta, whereas the course of the left crosses the aorta and is, therefore, more susceptible to anatomic compression. An aberrant right subclavian artery may compress the left brachiocephalic vein. Hypertension or age-related ectasia and tortuosity of the aorta may also compress the left brachiocephalic vein. In addition, retrosternal narrowing can also predispose to jugular venous reflux with left-sided injections.”
Computed Tomography Angiography of the Neurovascular Circulation Mohan S et al. Radiol Clin N Am 54 (2016) 147–162 - “The preferred site of injection is the
right antecubital vein that minimizes artifacts from dense contrast in the left brachiocephalic vein. Artifacts related to left-sided venous injection include artifact from dense contrast in the brachiocephalic vein obscuring adjacent arteries, reflux of contrast into the jugular veins simulating filling defects, and simple reflux into the internal jugular vein and/or vertebral veins or vertebral venous plexus reaching the dural venous sinuses and possible retrograde brain parenchymal enhancement.”
Computed Tomography Angiography of the Neurovascular Circulation Mohan S et al. Radiol Clin N Am 54 (2016) 147–162 - “CTA is a powerful and reliable tool to demonstrate the vasculature of the head and neck with proven utility for the detection and characterization of vascular diseases particularly in the acute setting. It may be used as the primary modality for detecting disease or as an adjunct tool for better characterizing known disease or assessing changes in the disease state over time. With the proliferation of CT scanners in the emergency departments, CTA examinations will continue to grow in numbers, helping to guide intervention in the emergency setting of neurovascular diseases.” Computed Tomography Angiography of the Neurovascular Circulation Mohan S et al. Radiol Clin N Am 54 (2016) 147–162
- Common indications for neurovascular CTA
• Arterial and venous aneurysms or pseudoaneurysms
• Stroke and vasospasm
• Atherosclerotic occlusive disease
• Nonatherosclerotic, noninflammatory vasculopathy
• Traumatic injuries to arteries and veins
• Arterial dissection and intramural hematoma - Common indications for neurovascular CTA
• Venous and dural sinus thrombosis
• Congenital vascular anomalies
• Vascular anatomic variants
• Vascular interventions (percutaneous and surgical)
• Vasculitis and collagen vascular diseases
• Vascular infection
• Head and neck tumors of vascular origin, with rich vascular supply or invading vascular structures
• Computed Tomography Angiography of the Neurovascular Circulation Mohan S et al. Radiol Clin N Am 54 (2016) 147–162
- “At present, surgery should remain the treatment of choice for MCA aneurysms. Surgical morbidity was low, and poor outcomes were due to an inclusive policy that aggressively managed poor-grade patients and complex aneurysms. This experience sets a benchmark that endovascular results should match before considering endovascular therapy an alternative for MCA aneurysms.”
Current management of middle cerebral artery aneurysms: surgical results with a "clip first" policy.
Rodríguez-Hernández A et. Al.
Neurosurgery. 2013 Mar;72(3):415-27. - “Compared with the new gold standard 3D DSA, 64-section CTA offers high sensitivity and specificity for detection of intracranial aneurysms. It could be readily used as a screening imaging method for detection of intracranial aneurysms.”
64-section multidetector CT angiography for evaluation of intracranial aneurysms: comparison with 3D rotational angiography.
Li Q et al.
Acta Radiol. 2013 Sep 24. [Epub ahead of print] - “The diagnostic performance of 64-detector CTA did not improve much compared with 16-detector CTA for detecting SIAs, especially for very small aneurysms. VR-RDSA is still necessary for patients with a history of subarachnoid hemorrhage if the CTA findings are negative.”
Evaluating of Small Intracranial Aneurysms by 64-Detector CT Angiography: A Comparison with 3-Dimensional Rotation DSA or Surgical Findings.
Zhang H et al.
J Neuroimaging. 2012 Dec 10.
- Carotid CT Angiography: Challenges
- Acquisition timing
- Venous contamination
- Difficulty in segmenting vascular structures from the skull base
- Artifacts generated by bone removal algorithms - “ The use of CT arteriography for the evaluation of carotid atherosclerosis is justified as an accurate and cost effective alternative to DSA and MR angiography.”
Dual-Energy CT: Vascular Applications
Vlahos I et al.
AJR 2012; 199:S87-S97 - Bone removal techniques for Carotid CTA
- Threshold based bone subtraction
- Unenhanced mask bone subtraction
- Dual energy CT - “ Dual energy bone subtraction for cervical CT arteriography compares very favorably to threshold-based bone subtraction. Early studies confirmed that dual energy bone subtraction was faster and more accurate versus threshold based bone subtraction without user modification (88% vs 7% technically adequate).”
Dual-Energy CT: Vascular Applications
Vlahos I et al.
AJR 2012; 199:S87-S97 - “ In comparison with DSA, dual energy bone subtraction including plaque removal shows good intertechnique correlation (r>0.9), although possible mild overestimation of stenosis with dual energy bone subtraction is possible, particularly in distinguishing severely stenotic and completely occluded vessels.”
Dual-Energy CT: Vascular Applications
Vlahos I et al.
AJR 2012; 199:S87-S97 - “ Although DECT of the brain and intracranial vessels has not been widely implemented and studied, it has great potential in neuroradiology.”
Dual-Energy CT of the Brain and Intracranial Vessels
Postma AA et al.
AJR 2012; 199:S26-S33 - “Bone removal in DECT angiography allow easier and faster acquisition and post-processing compared with conventional (subtraction) CTA. Removal of bone at skull base remains a matter of concern, but the development of better reconstruction algorithms and dedicated dual energy kernels may offer a solution.”
Dual-Energy CT of the Brain and Intracranial Vessels
Postma AA et al.
AJR 2012; 199:S26-S33
- "Multidetector row CT angiography has high sensitivity and specificity for detection of intracranial aneurysms, including small aneurysms, in patients with nontraumatic acute subarachnoid hemorrhage."
Detection of Intracaranial Aneurysms:MDCT Angiography Compared with DSA
Jayaraman MV et al.
Radiology 2004; 230:510-518 - "With increased reader experience, MDCT angiography may become the method of choice for aneurysm screening in patients with subarachnoid hemorrhage."
Detection of Intracaranial Aneurysms:MDCT Angiography Compared with DSA
Jayaraman MV et al.
Radiology 2004; 230:510-518