Relationship between cerebral aneurysms and variations in cerebral basal arterial network: a morphometric cross-sectional study in Computed Tomography Angiograms from a neurointerventional unit

ObjectiveSegments of cerebral basal arterial network (CBAN) dampen the peak pressure in blood flowing through these arteries, thus minimising the chances of development of cerebral aneurysms. The objective of this research was to find the relationship of occurrence of intracranial aneurysms to variations of the components of the CBAN.Design and settingThis is an observational, quantitative and retrospective research, which used cerebral CT angiography (CCTA) images.ParticipantsCerebral CTA of 145 adult patients of both sexes were studied.Main outcome measuresDiameters of segments of CBAN were measured in CCTA images and the relative size of each vessel was calculated to standardise for differences in overall arterial sizes among patients. Relationships among sizes of CBAN components were analysed. Presence of aneurysms in different parts of the CBAN was recorded.ResultsForty-six aneurysms in right internal carotid artery (ICA) and middle cerebral artery (MCA) and 32 aneurysms in left ICA and MCA segments were noted in 42 and 30 patients, respectively. Aneurysms in anterior communicating artery complex and vertebral-basilar arterial segments were seen in 27 and 8 patients, respectively, while they were not detected in parts of posterior cerebral artery (PCA). The significant (p<0.001) inverse relationships between sizes of posterior communicating artery and the first segment of PCA on both sides indicated that blood inputs to the second part of PCA were similar. Difference in means of the index of arterial size variation for people with aneurysms (mean 0.96, SD 0.23) and without aneurysms (mean 0.86, SD 0.22) was significant (p=0.015).ConclusionVariation in segments of CBAN was quantified. The peak pressure dampening mechanism in such arterial segments reduces the chances of development of aneurysms.

Evaluation the Frequency of Cerebral Arterial Fenestrations and Their Association with Cerebral Aneurysm by CT Angiography

Objective: Fenestration is a vascular variation that begins with a common origin, then splits into two parallel luminal channels that rejoins distally. We aim to evalute the frequency of cerebral arterial fenestrations and their association with cerebral aneurysm by computed tomography (CT) angiography. Methods: We retrospectively analyzed cerebral CT angiography of patients obtained between January 2017 and December 2020. Patients older than 18 years-old, without known vascular disease and previous surgery or interventional treatment were included the study. The location of the fenestration and aneurysms were noted. Results: CT angiographies of 887 patients (mean age 54.8 years, range 18-63 years; 405 women and 482 men) were evaluated. 164 fenestrastions found in 152 patients for a detection rate of 17.1%. Anterior communicating artery fenestrations were the most common (51.2%), followed by vertebrobasilar system fenestration (28.7%). In our study, no significant relationship was found between fenestration and aneurysm, regardless of localization (p>0.05). However, in the coexistence of fenestration and aneurysm, these are commonly located at the same localization (p: 0.005). Conclusion: Cerebral artery fenestration is an uncommon and mostly affects the anterior communicating artery and vertebrobasilar system. Cerebral artery fenestrations could be associated with aneurysms at the fenestration site. Further attention should be paid to the coexistence of aneurysm once intracranial artery fenestration has been found.

Proportion of Variant Anatomy of the Circle of Willis and Association with Vascular Anomalies on Cerebral CT Angiography

Background and Purpose. There is a wide variation in the anatomy of the CW in different individuals and population groups. The purpose of this study was to determine the proportion of variant anatomy of the circle of Willis (CW) and associated anomalies in patients with suspected cerebrovascular disease referred for cerebral computed tomography angiography (CTA) in two tertiary hospitals in Kenya. Methodology. This was a cross-sectional descriptive study conducted on 94 patients referred for cerebral CTA at the Kenyatta and Nairobi hospitals from August 2017 to February 2018. MIP and 3D reformatted images were analyzed by two senior radiologists to determine the final configuration of the CW and presence of vascular pathology. Vessels with diameters <0.8 mm were considered to be absent or hypoplastic. Chen et al. classification was used to determine the final configuration of CW. Results. Complete CW was seen in 37.2% (37.7% vs. 36.6% in males and females, respectively, p=0.909). Type A variant was the commonest anterior variant at 78.7%. Type E variant was the dominant posterior variant at 41.5%. Fetal PCA was demonstrated in 25.5%, unilateral > bilateral fetal PCA. Aneurysms were seen in 24.5% of patients. ACoA aneurysms were commonest at 43.6%. AVMs were seen in 8.5% of patients. Azygous ACA, fenestration, and duplication of vessels and persistent TA were not demonstrated. There is no significant association between aneurysms/AVMs and CW configuration. Conclusion. The findings in this study demonstrate slight differences in the CW configuration. A higher proportion of complete anterior CW was seen in female patients. Type A anterior and type E posterior circulation variants were the commonest in both males and females. No significant association was demonstrated between CW configuration and occurrence of aneurysms/AVMs in this study. Various methods of classification of CW configuration have been proposed with no standardized method to date, thus the need for consensus building between neuroanatomists, neurologists, neurosurgeons, and neuroradiologists for ease of comparison between similar future studies on the CW.

Cardiovascular computed tomography versus transoesophageal echocardiography after cryptogenic ischaemic stroke – a pilot study of 12 patients

Objective Transoesophageal echocardiography (TEE) is the gold standard for the detection of cardiac emboli sources in ischaemic stroke patients, but new computed tomography (CT) scanners are able to visualize the heart. This pilot study aimed to compare findings on TEE with combined cardiovascular scan and cerebral CT angiography in cryptogenic ischaemic stroke patients. Methods This pilot study enrolled patients with cryptogenic ischaemic stroke who underwent a combined cardiovascular and cerebral CT angiography scan and a TEE examination, which were interpreted in a blinded manner. Results Twelve patients with cryptogenic ischaemic stroke were included (mean age 56 years). Of these, 10 patients underwent both a combined cardiovascular and cerebral CT angiography and a TEE examination. All cardiovascular CT scans were readable at sinus rhythm. None of the simultaneous cerebral angiograms were compromised. Thrombi were not detected in any patients. Patent foramen ovale was visualized in five patients by TEE, while cardiovascular CT only identified three. Cardiovascular CT revealed in addition an X-ray negative pulmonary metastasis in one patient, aortic coarctation in another and significant coronary stenosis in four patients. Conclusion The sensitivity for detecting patent foramen ovale was considerably lower for cardiovascular CT than for TEE, however the cardiovascular CT revealed several other very important clinical findings.