Segment Of Posterior Cerebral Artery Research Articles

Quantitative evaluation of the effect of Circle of Willis structures on cerebral hyperperfusion: A multi-scale model analysis

Cerebral hyperperfusion occurs in some patients after superficial temporal artery–middle cerebral artery bypass surgery. However, there is uncertainty about cerebral hyperperfusion after bypass for patients with different Circle of Willis (CoW) structures.This study established a lumped–parameter model coupled with one–dimensional model (0–1D), whilst a deep learning model for predicting pressure drop (DLM–PD) caused by stenosis and a cerebral autoregulation model (CAM) were introduced into the model. Based on this model, 9 CoW structural models before and after bypass were constructed, to investigate the effects of different CoW structures on cerebral hyperperfusion after bypass. The model and the results were further validated by clinical data.The MSE of mean flow rates from 0–1D model calculation and from clinical measurement was 1.4%. The patients exhibited hyperperfusion in three CoW structures after bypass: missing right anterior segment of the anterior cerebral artery (mRACA1) (13.96% hyperperfusion); mRACA1 and foetal–type right anterior segment of posterior cerebral artery (12.81%), and missing anterior communicating artery and missing left posterior communicating artery (112.41%). The error between the average flow ratio from the model calculations and from clinical measurements was less than 5%.This study demonstrated that the CoW structure had a significant impact on hyperperfusion after bypass. The general 0–1D model coupled with DLM–PD and CAM proposed in this study, could accurately simulate the hemodynamic environment of different CoW structures before and after bypass, which might help physicians identify high–risk patients with hyperperfusion before surgery, and promote the development of non–invasive diagnosis and treatment of cerebrovascular diseases.

Clinical and radiographic outcomes after mechanical thrombectomy in medium-vessel posterior cerebral artery occlusions: Subgroup analysis from STAR.

Whereas mechanical thrombectomy (MT) has become standard-of-care treatment for patients with salvageable brain tissue after acute stroke caused by large-vessel occlusions, the results of MT in patients with medium-vessel occlusions (MEVOs), particularly in the posterior cerebral artery (PCA), are not well known. Using data from the international Stroke Thrombectomy and Aneurysm Registry (STAR), we assessed presenting characteristics and clinical outcomes for patients who underwent MT for primary occlusions in the P2 PCA segment. As a subanalysis, we compared the PCA MeVO outcomes with STAR's anterior circulation MeVO outcomes, namely middle cerebral artery (MCA) M2 and M3 segments. Of the 9812 patients in STAR, 43 underwent MT for isolated PCA MeVOs. The patients' median age was 69 years (interquartile range 61-79), and 48.8% were female. The median NIH Stroke Scale score was 9 (range 6-17). After recanalization, 67.4% of patients achieved successful recanalization (modified treatment in cerebral infarction score [mTICI] ≥ 2b), with a first-pass success rate of 44.2%, and 39.6% achieved a modified Rankin score of 0-2 at 90 days. Nine patients (20.9%) had died by the 90-day follow-up. In comparison with M2 and M3 MeVOs, there were no differences in presenting characteristics among the three groups. Patients with PCA MeVOs were less likely to undergo intra-arterial thrombolysis (4.7% PCA vs. 10.1% M2 vs. 16.2% M3, p = 0.046) or to achieve successful recanalization (mTICI ≥ 2b, 67.4%, 86.7%, 82.3%, respectively, p < 0.001); however, there were no differences in the rates of successful first-pass recanalization (44.2%, 49.8%, 52.3%, respectively, p = 0.65). We describe the STAR experience performing MT in patients with PCA MeVOs. Our analysis supports that successful first-pass recanalization can be achieved in PCA MEVOs at a rate similar to that in MCA MeVOs, although further study and possible innovation may be necessary to improve successful PCA MeVO recanalization rates.

Successful Thrombolysis in Artery of Percheron Infarction: Grabbed an Extremely Rare Opportunity

Artery of Percheron (AOP) is an uncommon anatomical variation in the posterior circulation neurovasculature. It is a single artery arising from P1 segment of posterior cerebral artery (PCA) which supplies bilateral paramedian thalami and the rostral midbrain and as a result, occlusion of it leads to bilateral thalamic and mesencephalic infarction. Due to very low incidence (ranges from 0.1% to 2% of all ischemic strokes) and varied presentation, the diagnosis of AOP infarction requires strong clinical and radiological suspicion and hence, AOP infarction is often missed and patients are rarely thrombolysed. Here we discuss a patient with acute altered sensorium who recovered completely in short time following treatment with intra-venous thrombolysis for bilateral medial thalamic ischemic stroke due to AOP occlusion.

Abstract TP199: Prominent Laterality of the Posterior Cerebral Artery on MR Angiography Before Mechanical Thrombectomy in Patients With the Middle Cerebral Artery Occlusion Predicts Long-Term Functional Outcome

Background and Purpose: Well-developed collateral flow is reported to be associated with a reduction of infarct volume, successful reperfusion, and better functional outcome in acute ischemic stroke (AIS). Relatively increased visualization of posterior cerebral artery (PCA) ipsilateral to the ischemic lesion on MR angiography (MRA), a sign of prominent PCA laterality (PCAL), represents the development of collateral flow from PCA to middle cerebral artery (MCA) territory. However, the prognostic value of PCAL on functional outcome in AIS patients having MCA occlusion and undergoing mechanical thrombectomy, is not well known. Methods: We retrospectively reviewed initial MRA scans of pre-morbidly independent patients treated with mechanical thrombectomy for M1-segment occlusion from September 2017 to May 2022. PCAL was defined as better visualization of ipsilateral PCA, compared to contralateral PCA, by one or more segments on MRA. We divided patients into two groups, those presenting PCAL and not, and compared the background characteristics, in-hospital management, and functional outcome between the two groups. Factors associated with favorable outcome (mRS score 0-2) at 3 months after onset were assessed using multivariate logistic regression analysis. Results: In total, 172 patients (76 female [44%], median age 77 [IQR 74.5-78.0] years, median NIHSS score 16 [15-18]) were included. Of these, 86 patients (50%) presented PCAL on initial MRA. There is no significant difference between the two groups in age, sex, major vascular risk factors, NIHSS on admission, DWI-ASPECTS, onset-to-recanalization time (OTR), and preclinical modified Rankin scale. Multivariate logistic regression analysis showed an adjusted odds ratio of 2.11 for a favorable outcome in patients with PCAL (95% CI: 0.986 to 4.53, P=0.054). When focused on the cases with OTR &gt;6 hours (n=53), PCAL was independently associated with favorable outcome (OR 5.77, 95% CI: 1.28 to 26.0, P=0.022). Conclusion: PCAL on initial MRA in patients with M1-segment occlusion predicts favorable long-term functional outcome after mechanical thrombectomy, especially in the case taking longer time from onset to recanalization.

The effects of P2 segment of posterior cerebral artery to thalamus blood supply pattern on gait in cerebral small vessel disease: A 7 T MRI based study

Gait disturbance is a manifestation of cerebral small vessel disease (CSVD). The posterolateral thalamus (PL), whose blood is mainly supplied by the P2 segment of posterior cerebral artery (P2-PCA), plays pivotal roles in gait regulation. We investigated the influence of the distance between P2-PCA and PL on gait with varying CSVD burden. 71 participants were divided into low and high CSVD burden groups. The distance from P2-PCA to PL was measured using 7 T TOF-MRA and categorized into an immediate or distant PCA-to-thalamus pattern. Functional connectivity (FC) and voxel-based morphometry were assessed to evaluate functional and structural alterations. In the low CSVD burden group, immediate PCA-to-thalamus supply strongly correlates with longer step length and higher wave phase time percent, and exhibited enhanced FCs in left supplementary motor area, right precentral cortex (PreCG.R). While in the high CSVD burden group, no association between PCA-to-thalamus pattern and gait was found, and we observed reduced FC in PreCG.R with immediate PCA-to-thalamus pattern. Higher CSVD burden was associated with decreased gray matter density in bilateral thalamus. However, no significant structural thalamic change was observed between the two types of PCA-to-thalamus patterns in all patients. Our study demonstrated patients with immediate PCA-to-thalamus supply exhibited better gait performance in low CSVD burden populations, which also correlated with enhanced FCs in motor-related cortex, indicating the beneficial effects of the immediate PCA-to-thalamus supply pattern. In the higher burden CSVD populations, the effects of PCA-to-thalamus pattern on gait are void, attributable to the CSVD-related thalamic destruction and impairment of thalamus-related FC.

Allelic effects on cerebral and carotid artery passive mechanical properties in young, adult, and aged hAPOE3 and hAPOE4 mice

Alzheimer’s disease (AD) is the most common form of dementia and among the leading mortalities in the US. There is growing evidence supporting a connection between AD and cardiovascular disease (CVD). Variant isoforms of apolipoprotein E (APOE) are risk factors for AD and CVD. Compared to the most common APOE isoform, APOE3 (E3), APOE4 (E4) increases AD risk. In order to study APOE-mediated processes, posterior cerebral arteries (PCA) and common carotid arteries (CCA) were isolated from mice expressing human-ApoE targeted replacement of APOE3 (B6.129P2- Apoe tm2(APOE*3)Mae N8) and APOE4 (B6.129P2- Apoe tm3(APOE*4)Mae N8)(Taconic Labs). Our objective was to determine whether the E3 and E4 allele cause different mechanical properties in the absence of extracellular Ca 2+ in the PCA and CCA isolated from young (Y, 3-4mo), adult (Ad, 12-15mo), and aged (Ag, 18-22mo), homozygous E3 and E4, male and female mice. We hypothesized that E4 would alter PCA and CCA structure/function when compared to age matched E3 cohorts. 5-8mm segments of PCA and CCA were isolated, cleaned of connective tissue, cannulated, and placed into an arteriograph. Upon equilibration, all vessels were challenged with 60mM [K + ] to assess viability. Vessels not responding to 60mM [K + ] were discarded. Mechanical characteristics, including lumen diameter (LD), wall thickness (WT), passive distensibility (PD), and stress/strain (S/S) were measured at intraluminal pressures ranging from 10-140mmHg. We observed no statistical differences in LD, PD, or S/S in PCAs and CCAs of Y and Ad, E3 and E4 mice. For LD and WT, Ag E3 was greater than Ag E4 (p&lt;0.05). In contrast, LD in PCAs and CCAs of Ag E3 mice was larger than in Ag E4 mice (p&lt;0.05). We further observed that PD and S/S in CCAs from Ag E3 was greater than in Ag E4 mice (p&lt;0.05), whereas there was no difference in PD and S/S in PCAs isolated from Ag E3 or E4 mice. The WT of PCA in Y E4 was significantly greater than Y E3 mice (p&lt;0.05). In contrast, WT in Ag E3 mice was larger than Ag E4 mice (p&lt;0.05). There was no difference between WT of Ad E3 and E4 mice. The WT of CCAs was significantly greater in Ag E3 vs Ag E4 mice (p&lt;0.05). There is no difference in WT in CCAs from Y (E3 vs E4) or Ad (E3 vs E4) mice. This data indicates aging has minimal effect on mechanical properties in the PCA. In contrast, CCAs in Ag E4 exhibited greater arterial stiffening as indicated by a decrease in their distensibility and leftward shift in S/S, as evidenced by greater stress for given amount of strain observed in PCAs of Ag E4 mice at increased intraluminal pressures. ABRC/ADHS18-205211 (JVE, TBJ, CBJ, DME), Arizona Alzheimer's Consortium (funded by the Arizona Department of Health Services, Contract No. CTR040636) and matching funds from Midwestern University (DME), Biomedical Sciences Program (BG, LJS, DME), Biomedical Sciences Start-up Funds (DME). LJS and ASH equally contributed as first authors. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Prediction of 90‐Day Home Time Among Patients With Medium‐Vessel Occlusion Undergoing Endovascular Thrombectomy

Background The benefit of endovascular thrombectomy for medium‐vessel occlusion (MeVO) strokes is unclear. We used 90‐day home time to explore outcomes in patients with MeVO versus large‐vessel occlusions treated with endovascular thrombectomy. Methods Data are from the QuICR (Quality Improvement and Clinical Research) provincial stroke registry and linked administrative data to identify patients who underwent endovascular thrombectomy in our center from January 2015 to December 2020. Imaging data were scored by 2‐physician consensus. We defined MeVO as occlusion beyond and including M2–middle cerebral artery, A2–anterior cerebral artery, or P2–posterior cerebral artery segments. Successful reperfusion was defined as Thrombolysis in Cerebral ischemia grades (≥2b/3). The primary outcome was patient home time (the number of nights a patient is back at their premorbid living situation without an increase in level of care within 90 days of the stroke) using random forest regression. Covariate contribution to home time was determined using partial dependence plots. Results Among 663 patients who underwent endovascular thrombectomy, 139 (20.9%) had MeVO (median age, 71 years; 50.4% women; median National Institutes of Health Stroke Scale, 16). The majority (82%) had good pial collaterals, 10.4% had a tandem extracranial carotid occlusion or stenosis, and 41.7% received intravenous thrombolysis. The most common site of occlusion was M2–middle cerebral artery (58.3%). One hundred eighteen (86.7%) patients achieved successful reperfusion (Thrombolysis in Cerebral Ischemia grades ≥2b/3). Using partial dependence plots, the mean predicted home times were similar in patients with MeVO (45.5 days) versus large‐vessel occlusions (44.6 days). Factors predicting lower 90‐day home time in patients with MeVOs were diabetes (−8.7 days), hypertension (−6.5 days), and atrial fibrillation (−3.5 days). There was no meaningful difference in predicted 90‐day home‐time by sex, baseline National Institutes of Health Stroke Scale, collateral grade, or thrombolysis. Conclusion Patients with MeVO who are selected for endovascular therapy with similar demographic and clinical profiles to large‐vessel occlusions can achieve similar 90‐day home time outcomes to large‐vessel occlusions.

Fenestrated P1 segment of posterior cerebral artery, partly duplicated posterior communicating artery.

Anatomic variations at the junction of primitive internal carotid and basilar arteries are exceedingly rare. We aimed at reporting such rare variants involving the posterior communicating artery (PComA) and the P1 segment of posterior cerebral artery (PCA). The circle of Willis was dissected in an adult cadaver after removal of the cranial vault and cerebral hemispheres. The basilar end was rotated axially to the right. The P1 segment of the right PCA was fenestrated and occupied the interpeduncular fossa. The right PComA passed over the oculomotor nerve to join the anterior arm of the P1 fenestration. On the opposite side, the PComA coursed supero-medially to the oculomotor nerve and it had a partly duplicated posterior end, with two arms, medial, larger, and lateral, thinner, inserting successively into the left PCA. Extremely rare anatomic variations of the circle of Willis should not be ignored when endovascular or microneurosurgical specific approaches are intended.

Extremely long posterior cerebral artery P1 segment.

Excluding aplasia and hypoplasia of the P1 segment of the posterior cerebral artery (PCA), anatomical variations in the PCA are rare. To our best knowledge, there are few reports of an extremely long P1 segment of the PCA. Herein, we report a rare case of an extremely long P1 segment of the PCA, which was diagnosed by 1.5-T magnetic resonance angiography (MRA). A 96-year-old woman was transferred by ambulance to our hospital with impaired consciousness. Her symptom improved, and magnetic resonance imaging showed no significant findings. MRA revealed an extremely long P1 segment of the left PCA. The length of the P1 segment of the left PCA was 27.3mm. The left posterior communicating artery (PCoA) was 20.9mm, which is not considered long. The left anterior choroidal artery branched from the internal carotid artery distal to the PCoA branching position. Basilar artery fenestration was also incidentally identified. Careful imaging assessment was important for identifying the extremely long P1 segment of the PCA in the present case. This rare anatomical variation can also be confirmed by 1.5-T MRA.

Optimization of 4D-MR angiography based on superselective pseudo-continuous arterial spin labeling combined with CENTRA-keyhole and view-sharing (4D-S-PACK) for vessel-selective visualization of the internal carotid artery and vertebrobasilar artery systems

PurposeThis study investigated the optimal labeling position and gradient moment for 4D-MR angiography based on superselective pseudo-continuous arterial spin labeling combined with CENTRA-keyhole and view-sharing (4D-S-PACK) for vessel-selective flow visualization of the internal carotid artery (ICA) and vertebrobasilar artery (VBA) systems. MethodsSeven healthy volunteers were scanned with a 3.0 T MR scanner. To visualize the ICA system, the labeling focus was placed in the right ICA at 55, 75 and 95 mm below the imaging slab. To visualize the VBA system, the labeling focus was placed in the basilar artery (BA), upper vertebral artery (VA upper), and lower vertebral artery (VA lower). Two sizes of labeling focus were created using gradient moments of 0.5 and 0.75 mT/m ms. The contrast-to-noise ratio (CNR) was measured in the middle cerebral artery (MCA) and posterior cerebral artery (PCA) branches. ResultsCNRs increased as the distance between the center of the imaging slab and the labeling position decreased in all MCA segments. CNRs obtained with VA lower tended to be higher than those obtained with BA and VA upper in all PCA segments. Selective vessel visualization was achieved with the gradient moment of 0.75 mT/m ms for the ICA and VBA system. ConclusionThe optimal 4D-S-PACK gradient moment was found to be 0.75 mT/m ms for the ICA and VBA systems. When visualizing the ICA system, the labeling position should be placed as close as possible to the imaging slab. When visualizing the VBA system, the labeling position should be placed at VA lower .

Abstract 1122‐000184: Cerebral Arterial Variations in Patients with Ischemic Stroke Undergoing Mechanical Thrombectomy

Introduction : This study aimed to determine what anatomical variants of the Circle of Willis (CoW) and the middle cerebral artery(MCA) are observed in patients with acute M1 occlusion and whether their prevalence differs from that described as “normal” in anatomy textbooks. Methods : We have performed a retrospective assessment of radiological examinations of patients with stroke due to middle cerebral artery M1 segment occlusion. All patients underwent mechanical thrombectomy from January 2015 until March 2021. The anatomy of the CoW was assessed on initial CT‐angiography and DSA. Branches of the MCA were observed on control DSA after recanalization. Results : A total of 100 patients were included in the analysis (58 females and 42 males, mean age: 71.6 +/‐ 13.9). Fully complete CoW was observed in 19% of patients. A total of 10% of patients had an incomplete anterior portion of CoW. In the incomplete anterior portion subgroup, the most common variation was the absence of anterior communicating artery (6% of total hemispheres), followed by the absence of one A1 (3% of total hemispheres). An incomplete posterior portion of CoW was identified in 79% of the patients. The absence of posterior communicating artery (PCoA) was observed in 59 patients. Sixteen patients had adult‐type PCoA, 3 patients had transitional‐type PCoA and 21 patients had fetal‐type posterior cerebral artery (PCA). In the subgroup of patients with fetal‐type posterior circle, 5 patients had no P1 segment of PCA. Anterior temporal branch of MCA was observed in 45% of the patients. Middle cerebral artery bifurcation was found in 80% of hemispheres, and trifurcation in 20%. In the bifurcation subgroup, 26% of MCAs had a dominating upper branch and 18% had a dominating lower branch. A duplicate MCA was observed in one hemisphere. Conclusions : In comparison to normal anatomy described in anatomy textbooks, the population of patients suffering from ischemic stroke due to M1 occlusion had a lower proportion of complete and closed CoW. A foetal type PCoA was observed to be prevalent (21%) in patients suffering from acute M1 occlusion. Detailed anatomical knowledge of anatomical variants of CoW in patients undergoing mechanical thrombectomy is essential for clinicians performing intravascular interventions and may aid procedure planning.

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...

Variants of the Circle of Willis as seen on magnetic resonance angiography and carotid siphon calcifications in community-dwelling older adults.

Information on the association between anatomical variants of the Circle of Willis (CoW) and intracranial atherosclerotic disease (ICAD) is limited and results are controversial. In this population-based study, we aimed to assess whether an incomplete CoW is associated with high calcium content in carotid siphons (a reliable biomarker of ICAD) in community-dwelling older adults of Amerindian ancestry. Individuals aged ≥60 years enrolled in the Three Villages Study received a head computed tomography (CT) and magnetic resonance angiogram (MRA) of intracranial vessels. The CoW was classified in complete or incomplete according to the presence or absence of one A1 segment of the anterior cerebral artery or one or both P1 segments of posterior cerebral arteries. Calcium content in carotid siphons was rated as low or high. A multivariate logistic model was fitted to assess the independent association between incompleteness of the CoW and high calcium content in carotid siphons, after adjusting for demographics and cardiovascular risk factors. A total of 581 individuals were enrolled (mean age: 71 ± 8.4 years; 57% women). MRA revealed an incomplete CoW in 227 (39%) individuals, and high-resolution CT disclosed high calcium content in carotid siphons in 185 (32%). A risk factor logistic regression model showed no independent association between incompleteness of the CoW and high calcium content in carotid siphons (odds ratio: 0.91; 95% confidence interval: 0.62-1.34; p = 0.631). Study results disclosed no association between anatomical variants of the CoW and the presence of high calcium content in carotid siphons.

Features of the cerebellar vascular supply (review)

Ischemic and hemorrhagic strokes remain the most devastating diseases of cerebrovascular system. They may cause disorders of speech, memory, mental health or movement. However, stroke can be prevented. Knowledge of the vascularization of the cerebellum and its variations is important for choosing a strategy of prevention and effective treatment of stroke. This review will discuss the variant anatomy of three pairs of cerebellar arteries: superior cerebellar artery (SCA), anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA). In most cases SCA and AICA arise from basilar artery, PICA arises from vertebral artery. SCA supplies tentorial cerebellar surface and dentate nucleus, AICA – petrosal surface of the cerebellum, flocculus, tegmentum, pons and middle cerebellar peduncles, PICA – suboccipital surface of the cerebellum, tonsil, inferior vermis, fastigial nucleus, choroid plexus and medulla. We conclude that SCA is the most constant artery and PICA is the most variable one. SCA can originate from the junction of the first segment of posterior cerebral artery and basilar artery or directly from the first segment of posterior cerebral artery. AICA can arise from vertebral artery or from common trunk with PICA. Rarely AICA arise from PICA. PICA can originate from basilar artery, extradural part of vertebral artery (C1-C2 or even C2-C3), ascending pharyngeal artery, proatlantal artery, ascending cervical artery or rarely from internal carotid artery. Many analyzed studies showed that PICA can be absent more often than AICA; SCA is almost always present. SCA is also duplicated more than other cerebellar arteries (mostly on the left). Significant difference was found in different studies about frequency of duplication of the AICA. PICA is rarely duplicated. Territories of cerebellar arteries change depending on their origin, course and also on the absence or duplication of the other ones. Many studies showed that SCA, AICA or PICA can dominate and send their branches to the territories of the other arteries which are absent or hypoplastic. The present study also describes classifications of segments of the cerebellar arteries, types of cerebellar vascular supply and superficial vascular network. Keywords: human, cerebellum, superior cerebellar artery, anterior inferior cerebellar artery, posterior inferior cerebellar artery.

Well-Formed Segmental Cerebral Arteries Dampen the Peak Systolic Pressure Lowering the Chances of Aneurysms

Background: The segments of cerebral basal arterial network (CBAN) dampen the peak systolic pressure in blood flowing through these arteries. The number of aneurysms occurring in segments of CBAN will vary with the ability of each arterial segment to dampen the peak systolic pressure. Materials and Methods: Diameters of segments of CBAN were measured in cerebral computed tomography angiography images of 145 patients 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 statistically analysed. Presence of aneurysms in parts of internal carotid artery (ICA), middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA), and vertebrobasilar (VB) arteries was recorded. Results: Forty-six aneurysms in right ICA and MCA and 32 aneurysms in left ICA and MCA segments were noted in 42 and 30 patients, respectively. Aneurysms in anterior communicating artery complex (AcomAC) and VB arterial segments were seen in 27 and 8 patients respectively, while they were not detected in parts of PCA. The significant (p<0·0001) inverse relationships between sizes of posterior communicating artery (PcomA) and the first segment of PCA on both sides indicated that blood inputs to the second part of PCA were similar. This smoothens vessels haemodynamics. Differences in means of the index of arterial size variation for people with aneurysms (0·96) and without aneurysms (0·86) was significant (p≤0·015). Aneurysms in ACA, PCA and VB arteries were less and was proposed that it is due to dampening of peak systolic blood pressures. The development of aneurysms occurring in CBAN depended on the degree of variation and asymmetry in its segments. Conclusion: Variation in segments of CBAN has been quantified. The peak pressure dampening mechanism in such arterial segments reduces the chances of development of aneurysms. Funding: None to declare Declaration of Interest: There is no conflict of interest with any of the authors. Ethical Approval: Randomly selected CCTA images of 145 patients archived in the Carestream data registry system at Royal Adelaide Hospital (RAH), South Australia between January 2011 and December 2019, were used in the study (male = 67, female = 78, mean age = 60·9 years) (Supplementary file 1). Human Research Ethics Board granted permission (approval number: H2014 -176) to access and use data from the Carestream data registry system (Vue RIS version 11·0·14·35).

Reference values for pulsatility index of fetal anterior and posterior cerebral arteries in prolonged pregnancy

To establish consistent normal reference values for fetal anterior cerebral artery (ACA) and posterior cerebral artery (PCA) pulsatility index (PI) in prolonged pregnancy. This prospective cross-sectional observational study included singleton normal prolonged pregnancies into two study groups according to the gestational age: from 40 + 0 to 40 + 6 and from 41 + 0 to 41 + 6 weeks. The PI was assessed in both anatomical segments of ACA (ACA-S1 and ACA-S2) and of PCA (PCA-S1 and PCA-S2) with color Doppler imaging and pulsed Doppler examination, and reference centiles charts were generated. PI values from the two investigated segments of each vessel were also compared. Data were obtained in 771 patients: n = 448 in the 40 + 0 and 40 + 6 weeks group, and n = 323 in the 41 + 0 and 41 + 6 weeks group. A moderate decrease in PI was observed as pregnancy progressed. No differences in PI values were found between the two anatomical segments of ACA and PCA. This study provides Doppler reference values for the fetal ACA and PCA PI. It also shows that Doppler examination could be performed indifferently in one of the two anatomical segments of these arteries.

Endovascular deep brain stimulation: Investigating the relationship between vascular structures and deep brain stimulation targets

BackgroundEndovascular delivery of current using ‘stentrodes’ – electrode bearing stents – constitutes a potential alternative to conventional deep brain stimulation (DBS). The precise neuroanatomical relationships between DBS targets and the vascular system, however, are poorly characterized to date. ObjectiveTo establish the relationships between cerebrovascular system and DBS targets and investigate the feasibility of endovascular stimulation as an alternative to DBS. MethodsNeuroanatomical targets as employed during deep brain stimulation (anterior limb of the internal capsule, dentatorubrothalamic tract, fornix, globus pallidus pars interna, medial forebrain bundle, nucleus accumbens, pedunculopontine nucleus, subcallosal cingulate cortex, subthalamic nucleus, and ventral intermediate nucleus) were superimposed onto probabilistic vascular atlases obtained from 42 healthy individuals. Euclidian distances between targets and associated vessels were measured. To determine the electrical currents necessary to encapsulate the predefined neurosurgical targets and identify potentially side-effect inducing substrates, a preliminary volume of tissue activated (VTA) analysis was performed. ResultsSix out of ten DBS targets were deemed suitable for endovascular stimulation: medial forebrain bundle (vascular site: P1 segment of posterior cerebral artery), nucleus accumbens (vascular site: A1 segment of anterior cerebral artery), dentatorubrothalamic tract (vascular site: s2 segment of superior cerebellar artery), fornix (vascular site: internal cerebral vein), pedunculopontine nucleus (vascular site: lateral mesencephalic vein), and subcallosal cingulate cortex (vascular site: A2 segment of anterior cerebral artery). While VTAs effectively encapsulated mfb and NA at current thresholds of 3.5 V and 4.5 V respectively, incremental amplitude increases were required to effectively cover fornix, PPN and SCC target (mean voltage: 8.2 ± 4.8 V, range: 3.0–17.0 V). The side-effect profile associated with endovascular stimulation seems to be comparable to conventional lead implantation. Tailoring of targets towards vascular sites, however, may allow to reduce adverse effects, while maintaining the efficacy of neural entrainment within the target tissue. ConclusionsWhile several challenges remain at present, endovascular stimulation of select DBS targets seems feasible offering novel and exciting opportunities in the neuromodulation armamentarium.

Doppler evaluation of the posterior cerebral artery in fetuses with transposition of great arteries.

Objective To observe Doppler ultrasound changes in the two segments of the posterior cerebral artery (PCA) in fetuses with transposition of the great arteries (TGA). Methods The peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and velocity-time integral (VTI) of the two segments of PCA (the first segment: PCAS1, the second segment: PCAS2) and of the middle cerebral artery (MCA) were compared in TGA fetuses and normal fetuses. The abnormality rate between the PCAS1-PI and MCA-PI was compared in TGA fetuses. Results The PCAS1-PI and MCA-PI were smaller in the TGA fetuses than in the controls (all P < 0.05), but the PCAS2-PI was unchanged (P > 0.05). The MCA-VTI, PCAS1-VTI, and PCAS2-VTI were larger in the TGA fetuses (all P < 0.05). In the TGA fetuses, the abnormality rate of the PCAS1-PI was significantly higher than that of the MCA-PI (P < 0.05). Conclusion In fetuses with TGA, there were hemodynamic differences between the two segments of the posterior cerebral arteries. Moreover, PCAS1 exhibited signs of vasodilatation more obviously than did the MCA in fetuses with TGA.

Dolichoectasia of the internal carotid artery terminus, posterior communicating artery, and posterior cerebral artery: The embryonic caudal ramus internal carotid segmental vulnerability legacy.

Dolichoectasia of the distal internal carotid artery, posterior communication artery (PCoA) and posterior cerebral artery is an extremely rare abnormality. Dolichoectasia of the internal carotid artery, PCoA and the P1 segment of posterior cerebral artery can be postulated its pathogenesis by the embryological perspective basis from caudal ramus of the internal carotid artery terminus. The pathogenesis and treatment strategy are not well established. We reviewed and proposed embryological perspective, pathogenesis, clinical setting, radiological findings and management of this rare malformation.

Abstract WP233: Distinct Vascular Profile in Middle-Aged Migraineurs: Higher Pulse Wave Velocity, Putaminal État Criblé and Incomplete Posterior Circle of Willis

Background: Migraineurs may develop stroke and cardiovascular diseases (CVD). We evaluated vascular findings in middle-aged migraineurs without CVD risks. Methods: Migraine was diagnosed according to ICHD-3 by direct interview and neurological examination. Migraine was classified into migraine with aura (MA) and migraine without aura (MO). Frequency of migraine attacks were denoted as &lt; 1 /mo or ≥ 1 /mo. Severity of migraine was scaled by Headache Impact Test-6. Usual CVD risk factors of smoking, obesity, hypertension, diabetes mellitus and dyslipidemia were examined. Brachial-ankle pulse wave velocity (baPWV) and ankle brachial index (ABI) were measured using a plethysmography. Brain magnetic resonance imaging (MRI) and angiography (MRA) were performed. Circle of Willis (CW) on MRA was morphologically classified into 2 types: complete posterior CW defined as the presence of both posterior communicating arteries and both P1 segments of posterior cerebral arteries, and other patterns of incomplete posterior CW (Ikeda et al. Headache 2007). Results: A total of 317 migraineurs (235 women and 82 men) were diagnosed. Thirty patients with CVD risk factors were excluded, and the study was completed in 287 migraineurs (215 women and 72 men), MA (n=56) and MO (n=231). Mean age (SD) was 44.0 (9.3) years. Consecutive 300 age- and sex-matched controls without migraine and CVD risks were prepared during the study. Compared to controls, baPWV was increased in migraineurs (P&lt;0.05) and MA patients (P&lt;0.01). ABI did not differ between migraineurs and controls. Other clinical findings of migraineurs were not linked to baPWV and ABI. MRI disclosed higher frequency of putaminal état criblé in migraineurs (P&lt;0.05) and MA patients (P&lt;0.01) compared to controls. Three MA patients were diagnosed with hereditary cerebral angiopathy of CADASIL (n=1), Moyamoya disease (n=1) and cavernous angioma (n=1). Morphological CW studies lower frequency of complete posterior CW in migraineurs (P&lt;0.05) and MA patients (P&lt;0.01) compared to controls. Conclusion: The present study suggested vascular changes of baPWV, putaminal état criblé and CW shape in migraineurs, especially in MA sufferers. The distinct vascular profile could contribute to higher risk of stroke and CVD in migraineurs.