The anatomic variations of the circle of Willis in preterm-at-term and term-born infants: an MR angiography study at 3T

Distinct Circle of Willis anatomical configurations in healthy preterm born adults: a 3D time-of-flight magnetic resonance angiography study

BACKGROUND

Preterm birth (< 37 weeks' gestation) alters cerebrovascular development due to the premature transition from a foetal to postnatal circulatory system, with potential implications for future cerebrovascular health. This study aims to explore potential differences in the Circle of Willis (CoW), a key arterial ring that perfuses the brain, of healthy adults born preterm.

METHODS

A total of 255 participants (108 preterm, 147 full-term) were included in the analysis. High-resolution three-dimensional Time-of-Flight Magnetic Resonance Angiography (3D TOF MRA) datasets were analysed, measuring vessel diameters and classifying segments into different groups of CoW anatomical variations. Statistical comparisons assessed the prevalence of each variant group between preterm and full-term populations, as well as the relationship between CoW variability, sex, and degree of prematurity.

RESULTS

We identified 164 participants with variant CoW configurations. Unilateral segment hypoplasia (30%) and unilateral segment absence (29%) were the most common variations, with over 50% related to the posterior communicating artery (PComA). However, the incidence of absent segments was lower in preterm adults, who were more likely to exhibit variants associated with complete CoW configurations compared to full-term adults (p = 0.025). Preterm males had a higher probability of a group 1 variant (circles with one or more hypoplastic segments only) than the full-term group (p = 0.024). In contrast, preterm females showed higher odds of a group 4a variant (circles with one or more accessory segments, without any absent segments) in comparison to their full-term counterparts (p = 0.020).

CONCLUSIONS

Preterm birth is linked to a distinct vascular phenotype of CoW in adults born preterm, with a higher likelihood of a CoW configuration with hypoplastic segments but a lower likelihood of absent segments. Future work should focus on larger prospective studies and explore the implications of these findings for normal development and cerebrovascular disease. Furthermore, TOF MRA might be a useful adjunct in the neurovascular assessment of preterm-born individuals.

Anatomical variations in the circle of Willis on magnetic resonance angiography in a south Trinidad population

Objectives

This article seeks to determine the prevalence of a complete circle of Willis (CoW) and its common morphological variations in a south Trinidad population, while also investigating the influence of gender, age, and ethnicity on CoW morphology.

Methods

A prospective, descriptive, cross-sectional study was done on the magnetic resonance images for consecutive patients who had a brain MRI/magnetic resonance angiography at a tertiary health institution in south Trinidad between October 2019 and September 2020. Patients with significant cerebrovascular disease and/or a history of prior neurosurgical intervention were excluded.

Results

A complete CoW was seen in 24.3%, with more complete circles observed in younger participants (≤45 years) and Afro-Trinidadians. No gender predilection for a complete CoW was demonstrated. The most common variations in the anterior and posterior parts of the circle were a hypoplastic anterior communicating artery (8.6%, n = 13) and bilateral aplastic posterior communicating arteries (18.4%, n = 28), respectively.

Conclusions

Significant variations exist in the CoW of a south Trinidad population with a frequency of complete in 24.3%, and more complete circles in younger patients and Afro-Trinidadians. Gender did not influence CoW morphology.

Advances in knowledge

Structural abnormalities in the CoW may be linked to future incidence of cerebrovascular diseases and should therefore be communicated to the referring physician in the written radiology report. Knowledge of variant anatomy and its frequency for a particular populations is also required by neurosurgeons and neuro-interventional radiologists to help with preprocedural planning and to minimize complications.

Asymmetry in cerebral perfusion from circle of Willis arterial variations in normal population

BACKGROUND

Angiographic and cadaveric studies have evidenced variations in the circle of Willis (CoW). Age-related changes in cerebral hemodynamics may be attributable to vascular variations.

OBJECTIVES

The objective is to assess interdependence of completeness of CoW with age using non-invasive MRA and cerebral perfusion using arterial spin labeling (ASL).

METHODS

This single-center, prospective study segregated 189 subjects into three groups: ≤5, 5 to 18, and >18 years. Angiographic (complete CoW and vascular asymmetry index) using TOF and contrast-enhanced- (CE-) MRA, and perfusion (perfusion asymmetry index) data using ASL were obtained.

RESULTS

One hundred and six (56.08%) subjects showed complete CoW on TOF and 100 (52.91%) on CE-MRA. Anterior and posterior collateral pathways were more prevalent in the younger population. Completeness of CoW decreased with increasing age, group 1 (54/60, 90% TOF; 51/60, 85% CE), group 2 (39/64, 60% TOF; 37/64, 56.92% CE), and group 3 (13/65, 20.31% TOF; 12/65, 18.75% CE); p-value < .0001. A statistically significant decrease in cerebral and cerebellar perfusion with increasing age was seen. Cerebellar to frontal perfusion change was higher in group 1. Fetal posterior cerebral artery (PCA) led to ipsilateral low and contralateral hyperperfusion flow asymmetries between occipital lobes.

CONCLUSIONS

This study shows that a complete CoW is commoner in pediatrics than adults and with increasing age, the completeness of CoW decreases paralleled by decrease in cerebral and cerebellar perfusion. There is age-related shift of perfusion from hindbrain to forebrain and the regression of PCoA occurs with increasing age leading to alterations in cerebral perfusion and hemodynamics.

Age-related changes in the completeness of the circle of Willis in children

PURPOSE

The circle of Willis is a circulatory anastomosis that supplies blood to the brain. If any of the bridging segments are hypoplastic or absent, the capacity for collateral flow in the setting of large vessel occlusion may be decreased. Outside of the neonatal period, the prevalence of a complete circle of Willis (CoW) in the pediatric population has not been well described. Our objectives include determining the prevalence of a complete CoW in children and identifying if there is an age-related "loss" of arterial segments.

METHODS

Following IRB approval, angiograms of the CoW performed on a 3-T MR platform from 2016 to 2020 on patients 21 years or younger were retrospectively reviewed. Any patient with underlying arterial pathology that may affect the CoW was excluded. Patient age and gender at the time of imaging were obtained.

RESULTS

In total, 592 pediatric CoW were assessed. Frequencies of completeness were calculated in two different fashions: scenario 1 where a CoW was characterized as complete even if it contained hypoplastic vessels (88.8%), and scenario 2 where it was characterized as complete after excluding hypoplastic vessels (44.0%). In both scenarios, our data showed that older age was more associated with an incomplete CoW (p < 0.0001). In addition, we found a higher percentage of males with an incomplete CoW compared with females (p < 0.0001).

CONCLUSIONS

The presence of a complete CoW is greater in our pediatric population than what has been reported in adults. The prevalence of an incomplete circle of Willis also increases significantly with age.

A new classification system for the anatomical variations of the human circle of Willis: A systematic review

The circle of Willis (CoW) is an anastomotic arterial network located on the base of the brain. Studies have shown that it demonstrates considerable anatomical variation in humans. This systematic review aimed to identify and catalogue the described anatomical variations of the CoW in humans to create a new, comprehensive variation classification system. An electronic literature search of five databases identified 5899 studies. A two‐phase screening process was performed, and studies underwent quality assessment. A total of 42 studies were included in the review. Data were extracted and circles were reconstructed digitally using graphics software. The classification system contains 82 CoW variations in five continuous groups. Group one contains 24 circles with one or more hypoplastic segments only. Group two contains 11 circles with one or more absent segments only. Group three contains 6 circles with hypoplastic and absent segments only. Group four contains 26 circles with one or more accessory segments. Group five contains 15 circles with other types of anatomical variation. Within each group, circles were subcategorised according to the number or type of segments affected. An original coding system was created to simplify the description of anatomical variations of the CoW. The new classification system provides a comprehensive ontology of the described anatomical variations of the CoW in humans. When used with the coding system, it allows the description and categorisation of recorded and unrecorded variants identified in past and future studies. It is applicable to current clinical practice and the anatomical community, including human anatomy education and research.

Anatomical variations of the circle of Willis in children

BACKGROUND

The morphology of the circle of Willis in adults has been thoroughly discussed in scientific literature. However, the morphology of the circle of Willis in pediatric patients is under-researched.

OBJECTIVES

We aimed to establish reference data for the morphology and variations of the circle of Willis in a population consisting of all pediatric age subgroups and to evaluate the possible temporal evolution of the circle of Willis in pediatric patients along with the variations between pediatric and adult populations.

MATERIALS AND METHODS

Our patient cohort included 263 pediatric patients ages 1-215 months. A total of 273 magnetic resonance (MR) angiography images were retrospectively analyzed for all circle of Willis vessels to compare the incidence of complete cases and variation frequency based on gender and age group.

RESULT

In our study of 273 MR angiograms from all age ranges in the pediatric population, we found a 56.1% circle of Willis completion rate. Overall completion rates were statistically significantly higher in the toddler and preschool age groups. The lowest completion rate was in the newborn-infant group (40%).

CONCLUSION

Circle of Willis completion rates and variations in pediatric populations are similar to those in adult populations; completion rates rise in toddler and preschooler age groups and decline as children grow into the school-age and adolescent period.

MR Imaging Differences in the Circle of Willis between Healthy Children and Adults

BACKGROUND AND PURPOSE

Asymmetries in the circle of Willis have been associated with several conditions, including migraines and stroke, but they may also be age-dependent. This study examined the impact of age and age-dependent changes in cerebral perfusion on circle of Willis anatomy in healthy children and adults.

MATERIALS AND METHODS

We performed an observational, cross-sectional study of bright and black-blood imaging of the proximal cerebral vasculature using TOF-MRA and T2 sampling perfection with application-optimized contrasts by using different flip angle evolution (T2-SPACE) imaging at the level of the circle of Willis in 23 healthy children and 43 healthy adults (4-74 years of age). We compared arterial diameters measured manually and cerebral perfusion via pseudocontinuous arterial spin-labeling between children and adults.

RESULTS

We found that the summed cross-sectional area of the circle of Willis is larger in children than in adults, though the effect size was smaller with T2-SPACE-based measurements than with TOF-MRA. The circle of Willis is also more symmetric in children, and nonvisualized segments occur more frequently in adults than in children. Moreover, the size and symmetry of the circle of Willis correlate with cerebral perfusion.

CONCLUSIONS

Our results demonstrate that the circle of Willis is different in size and symmetry in healthy children compared with adults, likely associated with developmental changes in cerebral perfusion. Further work is needed to understand why asymmetric vasculature develops in some but not all adults.

Distal anterior cerebral artery aneurysm with bilateral fetal posterior cerebral arteries and trifurcation of anterior cerebral artery

Developmental vascular anomalies of brain are non-modifiable risk factors for the development of aneurysms and are prone for rupture. We report one such association in a 44-year-old gentleman who succumbed to subarachnoid hemorrhage (SAH) secondary to ruptured distal anterior cerebral artery aneurysm associated with vascular anomalies in the anterior and posterior circulation that included trifurcation of anterior cerebral artery and bilateral fetal posterior cerebral arteries. We identified multiple anomalies in circle of Willis that could have contributed to the formation of aneurysm and early rupture. Knowledge of these variations is essential to plan early and optimum management with close follow-up.

Anatomical variations of the circle of Willis and their prevalence, with a focus on the posterior communicating artery: A literature review and meta-analysis

The circle of Willis is an anastomotic network of arteries surrounding the base of the brain, providing collateral circulation to prevent ischemia. It has, however, long been established that it exhibits considerable anatomical variation when compared to Thomas Willis' originally described circle. This study aimed primarily to determine an accurate prevalence of the variation of the circle of Willis in the general population and the prevalence of common posterior communicating artery variations. Additional aims were to explain why such a wide range of reported variations exist, and whether different types of studies report significantly different prevalence of variation. A comprehensive literature search identified 764 papers. A three-phase screening process was undertaken, involving a critical analysis of papers, and a total of 33 papers were selected for analysis and literature review. A descriptive statistics test with bootstrap was performed to estimate the average prevalence of variations. The estimated prevalence of general variation, unilateral, and bilateral posterior communicating artery hypoplasia or aplasia was 68.22 ± 14.32%, 19.45 ± 8.63%, and 22.83 ± 14.58%, respectively. Over half of the population exhibit a circle of Willis with some form of variation. To provide a more accurate estimation for the prevalence of variations, a universal classification system needs to be established, collating all the work from high-quality studies, to provide a comprehensive database of the circle's variations. Knowing the prevalence of variations and how they can impact neurosurgical approaches or patterns of ischemic pathology can be crucial in providing effective patient care.

Demographic age-related variation in Circle of Willis completeness assessed by digital subtraction angiography

OBJECTIVE:

Incomplete circle of Willis (CoW) configuration is an important risk factor for cerebrovascular pathology, namely aneurysm formation and ischemic stroke. This study was performed to characterize CoW variation using digital subtraction angiography and to identify demographic and physiologic features that may influence the risk of having an incomplete CoW configuration.

MATERIALS AND METHODS:

A retrospective review of 274 patients who underwent cerebral angiography by a single surgeon for any indication was conducted. Each CoW branch was graded as normal, hypoplastic, or aplastic. Univariate and multivariate regression analyses were conducted to assess the impact of age, gender, race, and certain comorbidities on CoW configuration.

RESULTS:

A complete CoW was identified in 37.23% of patients. In univariate analysis, patients <40 years old were more likely to have a complete CoW (odds ratio [OR]: 4.973, 95% confidence interval [CI]: 2.610–9.476, P < 0.001) as were patients <70 years old (OR: 2.849, 95% CI: 1.131–7.194, P < 0.05). Univariate analysis on demographic factors and comorbidities revealed CoW completeness to decrease with hypertension (OR: 0.575, 95% CI: 0.347–0.951, P = 0.031) and diabetes mellitus (OR: 0.368, 95% CI: 0.180–0.754, P = 0.006). Multivariable logistic regression analysis used to assess the impact of age on CoW completeness showed age to be an independent predictor of complete CoW, with an inverse correlation between increasing age and CoW completeness (OR: 0.955, 95% CI: 0.937–0.973, P < 0.001) after controlling for potential confounders including hypertension and diabetes mellitus.

CONCLUSIONS:

CoW configuration shows considerable variation with age; however, further investigation is required to elucidate the full impact of other demographic and vascular risk factors on CoW anatomy.

Genetic and Environmental Contributions to Variation in the Posterior Communicating Collaterals of the Circle of Willis

Variation in blood flow mediated by the posterior communicating collateral arteries (PComs) contributes to variation in the severity of tissue injury in obstructive disease. Evidence in animals and humans indicates that differences in the extent of PComs, i.e., their anatomic lumen diameter and whether they are present bilaterally, unilaterally, or absent, are a major factor. These differences arise during development since they are present at birth. However, the causal mechanisms are unknown. We used angiography after maximal dilation to examine involvement of genetic, environmental, and stochastic factors. The extent of PComs varied widely among seven genetically diverse strains of mice. Like pial collaterals in the microcirculation, aging and hypertension reduced PCom diameter, while in contrast, obesity, hyperlipidemia, metabolic syndrome, and diabetes mellitus had no effect. Naturally occurring intrauterine growth restriction had no effect on extent of PCom or pial collaterals in the adult. The number and diameter of PComs evidenced much larger apparent stochastic-dependent variation than pial collaterals. In addition, both PComs underwent flow-mediated outward remodeling after unilateral permanent MCA occlusion that varied with genetic background and was greater on the ipsilesional side. These findings indicate that variation in the number and diameter of PCom collateral arteries arises from stochastic factors and naturally occurring genetic variants that differ from those that cause variation in pial collateral arterioles. Environmental factors also contribute: aging and hypertension reduce PCom diameter. Our results suggest possible sources of variation of PComs in humans and provide information relevant when studying mouse models of occlusive cerebrovascular disease.

Are the Variants of the Circle of Willis Determined by Genetic or Environmental Factors? Results of a Twin Study and Review of the Literature

BACKGROUND

Anatomic variants of the circle of Willis (CW) are commonly observed in healthy subjects. Genetic and environmental factors influencing these variants remain unclear. Our aim was to assess the genetic and environmental background affecting variant CW phenotypes.

METHODS

A total of 122 adult healthy twins from the Hungarian Twin Registry (39 monozygotic (MZ) and 22 dizygotic (DZ) pairs, average age 49.7 ± 13.4 years) underwent Time-of-Flight magnetic resonance angiography and transcranial Doppler sonography. We investigated the anterior and posterior CW according to morphological categories. Prevalence and concordance rates of CW variants were calculated. MZ twins discordant for CW variants were analyzed for cardiovascular risk factors and altered blood flow.

RESULTS

Complete CW (45.0%) and bilaterally absent posterior communicating artery (PCoA) (22.5%) were the most prevalent variants in the anterior and posterior CW, respectively. There was no significant difference regarding the prevalence of variants across zygosity except for bilaterally hypoplastic PCoA (p = .02). DZ concordance was higher compared to MZ twins regarding morphological categories of the CW. Cardiovascular risk factors were not significantly associated with variant CW in MZ twins discordant to CW morphology. Flow parameters did not differ significantly among MZ twins discordant to CW variants.

CONCLUSION

CW variants may not be determined by substantial genetic effects and are not influenced by altered blood flow in healthy individuals. Further investigations are needed to identify potential environmental factors affecting these variants.

Investigation of circle of Willis variants and hemodynamic parameters in twins using transcranial color-coded Doppler sonography

Morphological and hemodynamic variations of the circle of Willis (CW) may have an important impact on cerebrovascular events. However, the environmental and genetic influence remains unclear. For this reason we studied the variations and hemodynamic parameters of the CW in twins using transcranial color-coded sonography (TCCS). Sixty-four twins, 19 monozygotic (MZ) and 13 dizygotic (DZ) pairs from the Italian Twin Registry (average age 45.0 ± 13.7 years) underwent TCCS and risk factor assessment. We examined CW morphology and recorded peak systolic velocity (PSV), end-diastolic velocity (EDV) and pulsatility index (PI). Raw heritability was determined for hemodynamic parameters, whereas concordance and discordance rates were calculated for CW morphological variants. A normal CW anatomy was observed in the majority of MZ and DZ twins (76.5% and 92.3%, respectively). The most frequent variant was a missing anterior cerebral artery (ACA). There was no significant difference in the prevalence of most CW variants depending on the zigosity. Concordance rates were low regarding the presence of variant CW anatomy both in MZ and DZ groups (0.14 and 0.00, respectively). Women had a significantly higher PI in vertebral arteries (VA) and in the right ACA (p = 0.01, p = 0.02 and p < 0.01, respectively). An inverse correlation was observed between hemodynamic parameters and age. Morphological variants of the CW do not seem to be heritable; they are most likely determined by environmental factors. In contrast, hemodynamic parameters of the CW are moderately heritable and this might have implications in the management and prevention of cerebrovascular diseases.

Utility of Neurovascular Imaging in Acute Neonatal Arterial Ischemic Stroke

OBJECTIVE

To evaluate the prevalence of magnetic resonance angiography (MRA) findings and clinically characterize neonates with arterial ischemic stroke (AIS) who have abnormal or variable vasculature.

STUDY DESIGN

This was a single-center, retrospective study of patients with neonatal stroke from 1991 to 2012. We reviewed charts and neuroimaging, including MRA, in neonates with AIS. Clinical data of patients with MRA findings were compared with the control group of neonates with AIS and a normal MRA.

RESULTS

We identified 142 cases of neonatal AIS, of which 81 patients had magnetic resonance imaging and MRA. Among the neonates with arterial neuroimaging, 29 had arterial findings (for a prevalence rate of 20%-35%). The majority of the findings were stenotic or hypoplastic branches. Two patients had presumed carotid artery dissection. Low Apgar scores and the presence of sepsis were significantly (P <.05) more common in neonates with MRA findings.

CONCLUSION

The prevalence of arterial abnormalities or variations in neonatal AIS has been underestimated because neurovascular imaging is often not performed. We recommend an MRA for neonates with AIS, particularly those who have low Apgar scores and/or sepsis, to rule out a vasculopathy that may warrant therapeutic intervention.

Completion of the Circle of Willis Varies by Gender, Age, and Indication for Computed Tomography Angiography

OBJECTIVE

The circle of Willis (CoW) is the foremost anastomosis and blood distribution center of the brain. Its effectiveness depends on its completion and the size and patency of its vessels. Gender-related and age-related anatomic variations in the CoW may play an important role in the pathogenesis of cerebrovascular diseases. In this study, we analyzed computed tomography angiograms (CTAs) to assess for differences in CoW completion related to gender, age, and indication for CTA.

METHODS

A total of 834 CTAs were retrospectively analyzed for all CoW vessels to compare the incidence of complete CoW and variation frequency based on gender, age, and indication.

RESULTS

The incidence of complete CoW was 37.1% overall. CoW completion showed a statistically significant decrease with increasing age for all age groups in both men (47.0%, 29.4%, 18.8%) and women (59.1%, 44.2%, 30.9%). Completion was greater in women (43.8%) than in men (31.2%) overall and for all age groups. These gender differences were all statistically significant except for the 18-39 years age group. The most frequent of the 28 CoW variations were absent posterior communicating artery (PCOM) bilaterally (17.1%), right PCOM (15.3%), and left PCOM (10.9%). Ischemic stroke and the 18-39 years age group of hemorrhagic stroke showed a statistically significant reduction in completion relative to trauma.

CONCLUSIONS

The incidence of complete CoW is likely greater in women for all age groups and likely decreases with age in both genders. The most frequently absent vessel is likely the PCOM, either unilaterally or bilaterally. Completion may play a role in ischemic stroke and a subset of patients with hemorrhagic stroke.

The cerebral basal arterial network: morphometry of inflow and outflow components

The aim of this project was to study how the morphology of the incoming and outgoing arterial components of the cerebral basal arterial network influence the blood flow to the brain. The cerebral basal arterial network consists of the circulus arteriosus cerebri anteriorly and the basilar artery posteriorly. Diameters of inflow vessels (bilateral vertebral and internal carotid arteries), connecting vessels (anterior communicating, basilar and bilateral posterior communicating arteries) and outflow vessels (anterior, middle and posterior cerebral arteries) were measured and cross-sectional areas calculated in 51 cadaveric brain specimens. The individual and the average cross-sectional areas of inflow arteries (51.43 mm² ) were significantly bigger than the major outflow arteries (37.76 mm² ) but smaller than the combined cross-sectional areas of outflow (37.76 mm² ) and connecting (25.33 mm² ) arteries. The difference in the size of arterial cross-sectional area and the presence of the connecting arteries in the cerebral basal arterial network provides a mechanism for lowering peaks in pressure, and demonstrates a function of the cerebral basal arterial network.

PREMM: preterm early massage by the mother: protocol of a randomised controlled trial of massage therapy in very preterm infants

Background

Preterm infants follow an altered neurodevelopmental trajectory compared to their term born peers as a result of the influence of early birth, and the altered environment. Infant massage in the preterm infant has shown positive effects on weight gain and reduced length of hospital stay. There is however, limited current evidence of improved neurodevelopment or improved attachment, maternal mood or anxiety. The aim of this study is to investigate the effects of infant massage performed by the mother in very preterm (VPT) infants. Effects on the infant will be assessed at the electrophysiological, neuroradiological and clinical levels.  Effects on maternal mood, anxiety and mother-infant attachment will also be measured.

Methods/Design

A randomised controlled trial to investigate the effect of massage therapy in VPT infants. Sixty VPT infants, born at 28 to 32 weeks and 6 days gestational age, who are stable, off supplemental oxygen therapy and have normal cranial ultrasounds will be recruited and randomised to an intervention (infant massage) group or a control (standard care) group. Ten healthy term born infants will be recruited as a reference comparison group. The intervention group will receive standardised massage therapy administered by the mother from recruitment, until term equivalent age (TEA). The control group will receive care as usual (CAU). Infants and their mothers will be assessed at baseline, TEA, 12 months and 24 months corrected age (CA), with a battery of clinical, neuroimaging and electrophysiological measures, as well as structured questionnaires, psychoanalytic observations and neurodevelopmental assessments.

Discussion

Optimising preterm infant neurodevelopment is a key aim of neonatal research, which could substantially improve long-term outcomes and reduce the socio-economic impact of VPT birth. This study has the potential to give insights into the mother-baby relationship and any positive effects of infant massage on neurodevelopment. An early intervention such as massage that is relatively easy to administer and could alter the trajectory of preterm infant brain development, holds potential to improve neurodevelopmental outcomes in this vulnerable population.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12612000335897. Date registered: 22/3/2012.

Morphology of the cerebral arterial circle in the prenatal and postnatal period of Serbian population

BACKGROUND

In the literature, there are descriptions of morphological types of the cerebral arterial circle (CAC) of different human populations around the world, but not the Serbian population. This additionally inspired the authors to present the results of previous and current researches of CAC's configuration in the prenatal, as well as in the postnatal period.

METHOD

The study was performed on CACs of 190 human fetuses and 143 adult cadavers. The caliber and configuration of fetal vessels were examined under the operating microscope, while the same of adults were studied using the ImageJ. Statistical analysis of CACs vessels' calibers was performed. Classification into one of CAC morphological types was based on the presence of hypoplasia of corresponding vessel(s).

RESULTS

There was not only significant difference of the three communicating arteries calibers before and beyond the 16th week of gestation. Calibers of the right pre-communicating part of the posterior cerebral artery and right cerebral part of the internal carotid artery were significantly higher in male than in female adults. There were 13 morphological types of CACs from the prenatal to the postnatal period. Most frequent CAC types were the type I (normal CAC) prenatally and type IV (unilateral hypoplasia of the posterior communicating artery) in the postnatal period. There were not relationships between the cerebral cause of death and a presence of aneurysm.

CONCLUSION

Results of this study will be the basis for future investigation of CACs according to the same or different ages and causes of disease and/or death.

Pediatric high-field magnetic resonance imaging

High-field 3 T magnetic resonance (MR) imaging provides greater signal-to-noise ratio (SNR) compared with 1.5 T systems. Various MR imaging clinical applications in children can benefit from improvements resulting from this increased SNR. High-resolution imaging of the brain, arterial spin labeling perfusion imaging, diffusion imaging, MR spectroscopy, and imaging of small anatomic parts are some areas in which these improvements can increase our clinical diagnostic capabilities. However, challenges inherent to 3 T imaging become more relevant in children. The use of 3 T imaging in children has allowed better diagnostic efficacy in neuroimaging, but certain technique modifications may be required for optimal imaging.

A simple technique for morphological measurement of cerebral arterial circle variations using public domain software (Osiris)

This article describes a straightforward method to measure the dimensions and identify morphological variations in the cerebral arterial circle using the general-purpose software program Osiris. This user-friendly and portable program displays, manipulates, and analyzes medical digital images, and it has the capability to determine morphometric properties of selected blood vessels (or other anatomical structures) in humans and animals. To ascertain morphometric variations in the cerebral arterial circle, 132 brains of recently deceased fetuses, infants, and adults were dissected. The dissection procedure was first digitized, and then the dimensions were measured with Osiris software. Measurements of each vessel's length and external diameters were used to identify and classify morphological variations in the cerebral arterial circle. The most commonly observed anatomical variations were uni- and bilateral hypoplasia of the posterior communicating artery. This study demonstrates that public domain software can be used to measure and classify cerebral arterial circle vessels. This method could be extended to examine other anatomical regions or to study other animals. Additionally, knowledge of variations within the circle could be applied clinically to enhance diagnostic and treatment specificity.

MRI of perinatal brain injury

MRI is invaluable in assessing the neonatal brain following suspected perinatal injury. Good quality imaging requires adaptations to both the hardware and the sequences used for adults or older children. The perinatal and postnatal details often predict the pattern of lesions sustained and should be available to aid interpretation of the imaging findings. Perinatal lesions, the pattern of which can predict neurodevelopmental outcome, are at their most obvious on conventional imaging between 1 and 2 weeks from birth. Very early imaging during the first week may be useful to make management decisions in ventilated neonates but brain abnormalities may still be subtle using conventional sequences. Diffusion-weighted imaging (DWI) is very useful for the early identification of ischaemic tissue in the neonatal brain but may underestimate the final extent of injury, particularly basal ganglia and thalamic lesions. MR imaging is an excellent predictor of outcome following perinatal brain injury and can therefore be used as a biomarker in interventional trials designed to reduce injury and improve neurodevelopmental outcome.