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Congenital agenesis of the internal carotid artery is a very rare anomaly. Intracranial circulation in the involved internal carotid artery territory is maintained by collateral circulation from the contralateral internal carotid artery through the anterior communicating artery and from the vertebrobasilar system through the posterior communicating artery. Usually, patients with internal carotid artery agenesis are asymptomatic due to collateral circulation, but they may present with headache, seizures, or transient ischemic attack. Aneurysms have also been reported to be associated with this entity. Computed tomography angiography, magnetic resonance angiography, and digital subtraction angiography are commonly used modalities to make the diagnosis. Unenhanced skull base computed tomography will show the absence of carotid canal, thus differentiating from carotid hypoplasia. We report on a case of right internal carotid artery agenesis with discussion of embryogenesis, clinical presentation, and imaging findings.

Introduction Some of the latest groundbreaking trials suggest that noncontrast cranial computed tomography and computed tomography-angiography are sufficient tools for patient selection within six hours of symptom onset. Before endovascular stroke therapy became the standard of care, patient selection was one of the most useful tools to avoid futile reperfusions. We report the outcomes of endovascularly treated stroke patients selected with a perfusion-based paradigm and discuss the implications in the current era of endovascular treatment. Material and methods After an interdisciplinary meeting in September 2012 we agreed to select thrombectomy candidates primarily based on computed tomography perfusion with a cerebral blood volume Alberta Stroke Program Early Computed Tomography Scale (CBV-ASPECTS) of Results In 39 patients with a mean age of 69 years and a median admission National Institute of Health Stroke Scale of 17 the successful reperfusion rate was 74% and the favourable outcome rate at 90 days was 56%. Compared to previously published data from our database 2007–2011, we found that a two-point increase in median CBV-ASPECTS was associated with a significant increase in favourable outcomes. Conclusion Computed tomography perfusion imaging as an additional selection criterion significantly increased the rate of favourable clinical outcome in patients treated with mechanical thrombectomy. Although computed tomography perfusion has lost impact within the six-hour period, we still use it in cases beyond six hours as a means to broaden the therapeutic window.

Susceptibility weighted imaging (SWI) is an essential magnetic resonance imaging sequence in the assessment of acute ischemic stroke. In this article, we discuss the physics principals and clinical application of conventional SWI and multi-echo SWI sequences. We review the research evidence and practical approach of SWI in acute ischemic stroke by focusing on the detection and characterization of thromboembolism in the cerebral circulation. In addition, we discuss the role of SWI in the assessment of neuroparenchyma by depiction of asymmetric hypointense cortical veins in the ischemic territory (surrogate tissue perfusion), detection of existing microbleeds before stroke treatment and monitoring for hemorrhagic transformation post-treatment. In conclusion, the SWI sequence complements other parameters in the stroke magnetic resonance imaging protocol and understanding of the research evidence is vital for practising stroke neurologists and neuroradiologists.

Isolated aneurysms of spinal arteries are rare. Spinal artery aneurysms are commonly found in association with spinal cord arteriovenous malformation and coarctation of aorta and rarely with aortic arch interruption and Klippel-Trenaunay syndrome. Spinal angiograms are the gold standard for diagnosing these spinal artery aneurysms but with the advances in computed tomography technology these aneurysms can also be very well demonstrated in computed tomography angiograms. We describe three cases of anterior spinal artery aneurysm, those are flow related aneurysms, associated with coarctation of aorta and with Takayasu arteritis.

Stroke is associated with vulnerable carotid artery plaques showing specific histopathologic features, namely a lipid-rich necrotic core, intraplaque hemorrhage, ulceration, and thin fibrous cap. While ultrasound and computed tomography (CT) can identify carotid plaques and determine the extent of stenosis, magnetic resonance imaging (MRI) provides further information regarding plaque composition and morphology. In this feasibility study, three patients with symptomatic, moderately stenosed plaques were imaged with CT angiography (CTA) and MRI (3T and 1.5T) without a dedicated receiver coil. The patients subsequently underwent carotid endarterectomy with en-bloc excision of the plaque. The CT and MR images were analyzed independently by three neuroradiologists to identify vulnerable plaque features. The images were correlated with the histopathology to confirm the findings. All three patients had one or more vulnerable plaque features on histopathology. MRI allowed for better characterization of these features when compared to CTA. The pre- and post-contrast T1-weighted (T1W) images were most helpful for identifying the lipid-rich necrotic core and thin fibrous cap, while the time of flight-magnetic resonance angiography (TOF-MRA) and contrast-enhanced (CE)-MRA were excellent for detecting plaque hemorrhage and ulceration, respectively. The 3T images showed superior spatial and contrast resolution compared to the 1.5T images for all sequences. By providing direct correlation between imaging and histopathology, this study demonstrates that 3T MRI without a dedicated surface coil is an excellent tool for assessing plaque vulnerability. In smaller hospitals or those with limited resources, it is reasonable to consider conventional MRI for patient risk stratification. Further studies are needed to determine how MRI and plaque vulnerability can be incorporated into routine clinical practice.

Background Intracranial pseudoaneurysm formation due to a ruptured non-traumatic aneurysm is extremely rare. We describe the radiological findings and management of pseudoaneurysms due to ruptured cerebral aneurysms in our case series and previously reported cases. Patients and methods Four additional and 20 reported patients presenting with subarachnoid hemorrhage (SAH) are included. Radiological findings and clinical features of these patients were reviewed. Results In our series, three-dimensional computed tomographic angiography (3D-CTA) and/or angiography showed an irregular- or snowman-shaped cavity extending from the parent artery. The radiological examination additionally revealed delayed filling and retention of contrast medium. These findings were the same as previously reported cases. One patient underwent direct clipping of the true aneurysm. For the other three patients with aneurysms at the basilar and anterior communicating arteries, the true portion of the aneurysm was embolized with platinum coils. During the procedures, care was taken not to insert the coils into the distal pseudoaneurysm portion to prevent rupture. The review of 24 cases revealed that the location of the aneurysms was most frequent in the anterior communicating artery (41.7%), and 86.7% of patients were in a severe stage of SAH (>Grade 3 in WFNS or Hunt & Kosnik grading) implying abundant SAH. Conclusions Pseudoaneurysm formation in SAH after non-traumatic aneurysm rupture is rare. However, in cases with an irregular-shaped aneurysm cavity, pseudoaneurysm formation should be taken into consideration.

Background and importance Intraorbital arteriovenous fistulas (IOAVFs) are rare and cause eye redness, exophthalmos, blurry vision and bruit. Whereas in the past they were treated conservatively, surgically or transarterially, recent developments in transvenous embolization have improved their treatment. In this paper the authors report three cases of IOAVFs treated endovascularly and review the evolution of treatment options. Methods Three cases of purely IOAVF enrolled in our center were reported and a PubMed literature search was performed using “pure intraorbital arteriovenous fistula” and “arteriovenous fistula of the optic nerve sheath.” A total of 21 papers were reviewed in full, focusing primarily on the treatment and outcomes. Results A total of 26 patients were obtained, including our three patients and 23 patients reported in the literature. In nine patients treated conservatively, four spontaneous occlusions, one visual deterioration and four cases with unknown outcome were reported. In another 18 patients, 29 therapies (including five surgical treatment, 11 transarterial embolizations and 13 transvenous embolizations) were attempted and resulted in 12 cures, five visual deteriorations and one without reported outcome. More recently, transvenous embolization has become the mainstay of IOAVF treatment. Of the 21 patients assessed between 2000 and 2013, a transvenous approach was attempted in 13 patients; nine patients were cured without any adverse events. Conclusion Development and improvement of transvenous techniques are found to be safe and effective for patients with IOAVF.