Blood redistribution in the fetal brain during chronic hypoxia
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Studies on blood flow velocity in the fetal middle cerebral artery have revealed signs of brain sparing in chronic hypoxia. These signs of brain sparing can disappear in the terminal case, but whether this applies to the whole brain or only parts of it is unknown.Velocity waveforms of the middle cerebral, anterior cerebral and posterior cerebral arteries were recorded in 221 pregnancies complicated by pregnancy-induced hypertension. The presence of brain sparing (pulsatility index < 2 standard deviations) was noted and correlated to outcome of pregnancy, including emergency operative intervention and/or neonatal distress.Signs of brain sparing in the anterior cerebral artery were found in 90 fetuses, and in the middle cerebral and posterior cerebral arteries in 52 and 65, respectively. Signs of brain sparing in the anterior cerebral artery showed the strongest relationship to adverse perinatal outcome. The anterior cerebral artery was the only vessel in which signs of brain sparing were predictive of perinatal mortality.Velocimetry of the anterior cerebral artery appears to be superior to that of the middle cerebral and posterior cerebral arteries as a means to predict adverse perinatal outcome. Anterior cerebral artery brain sparing may therefore be less transitory than sparing in the middle cerebral and posterior cerebral arteries, possibly suggesting that the frontal lobes are spared longer than the lateral and occipital regions of the fetal brain.Keywords:
Anterior cerebral artery
Posterior cerebral artery
Cerebral hypoxia
Studies on blood flow velocity in the fetal middle cerebral artery have revealed signs of brain sparing in chronic hypoxia. These signs of brain sparing can disappear in the terminal case, but whether this applies to the whole brain or only parts of it is unknown.Velocity waveforms of the middle cerebral, anterior cerebral and posterior cerebral arteries were recorded in 221 pregnancies complicated by pregnancy-induced hypertension. The presence of brain sparing (pulsatility index < 2 standard deviations) was noted and correlated to outcome of pregnancy, including emergency operative intervention and/or neonatal distress.Signs of brain sparing in the anterior cerebral artery were found in 90 fetuses, and in the middle cerebral and posterior cerebral arteries in 52 and 65, respectively. Signs of brain sparing in the anterior cerebral artery showed the strongest relationship to adverse perinatal outcome. The anterior cerebral artery was the only vessel in which signs of brain sparing were predictive of perinatal mortality.Velocimetry of the anterior cerebral artery appears to be superior to that of the middle cerebral and posterior cerebral arteries as a means to predict adverse perinatal outcome. Anterior cerebral artery brain sparing may therefore be less transitory than sparing in the middle cerebral and posterior cerebral arteries, possibly suggesting that the frontal lobes are spared longer than the lateral and occipital regions of the fetal brain.
Anterior cerebral artery
Posterior cerebral artery
Cerebral hypoxia
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Objective: To observe the courser and morphology of the major cerebral arteries and the inner diameters in their origin, and the display rate of their branches at all levels on multi-slice spiral CT angiographic (MSCTA) imaging in healthy adults. The authors expect to provide useful imaging data for the diagnosis of cerebrovascular diseases. Methods: Forty cases normal series images were selected from the cerebral arterial 64-slice MSCTA images of health volunteer randomly. The inner diameter in their origin, courser and morphology of the main cerebral arteries were observed by an ADW 4.2 workstation. The display rate of their branches at all levels was also calculated. Results: The frequent variability was found in the A1 segment of anterior cerebral artery (ACA), anterior communicating artery (ACoA), posterior communicating artery (PCoA), and P1 segment of posterior cerebral artery (PCA) which constitute a circle of willis, and the noticeable variability was PCoA. The frequency of MSCTA to display the major cerebral arteries including the end segment of ICA, A1 segment of ACA, middle cerebral artery (MCA), PCA, ophthalmic artery (OA), AcoA, PcoA, and anterior choroidal artery (AchA) was 100%, 95%, 100%, 100%, 100%, 92.5%, 58.8% and 72.5% respectively. The inner diameters of the main cerebral arteries were 4.013±0.770 mm, 2.709±0.877 mm, 3.498±0.640 mm, 2.025±0.608 mm, 1.640±0.334 mm, 1.491±0.697 mm and 1.460±0.483 mm respectively for the end segment of ICA, ACA, MCA, PCA, OA, PcoA, and AchA. Conclusion: The cerebral arterial variabilities in healthy adults distributed predominantly in the circle of willis. The diameter of the cerebral arteries is related to their territorial distribution and hemodynamic factors.
Anterior cerebral artery
Posterior cerebral artery
Circle of Willis
Posterior communicating artery
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The color flow mapping method makes it possible to identify small vessels presently not detected on B‐mode imaging. The main cerebral arteries of normal human fetuses, anterior, middle, and posterior arteries, were investigated by color‐coded Doppler in 45 normal pregnancies. The Pourcelot index R was calculated at different stages of the pregnancy. The values of R (anterior cerebral artery), R (middle cerebral artery), and R (posterior cerebral artery) were compared in each fetus. No significant differences were found when comparing all of the R (anterior cerebral artery) and R (middle cerebral artery) or the R (anterior cerebral artery) and R (middle cerebral artery) at the same gestational age. On the contrary, for each fetus, at any gestational age, the R (anterior cerebral artery) and the R (middle cerebral artery) indices were significantly different (P < 0.01); the index in the middle cerebral artery was higher than that of the anterior cerebral artery. The same difference was observed when comparing R (posterior cerebral artery) and R (middle cerebral artery). The index of the middle cerebral artery was significantly higher than that of the posterior cerebral artery (P < 0.001). On the other hand, no significant difference was found between R (anterior cerebral artery) and R (posterior cerebral artery) at any gestational age (P = 0.4).
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Posterior cerebral artery
Posterior communicating artery
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Posterior cerebral artery
Anterior cerebral artery
Superficial temporal artery
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Objective To investigate the morphology of the cerebral arteries with multi-slice spiral CT angiography(MSCTA) in Chinese adults.Methods MSCTA of 129 Chinese adults were retrospectively analyzed to observe the morphology and patterns of the cerebral arteries.Results On MSCTA,the hypogenesis rate of A1 segment of anterior cerebral artery was 14.73%,and its absence rate 5.43%.The variations of the A1 segment of anterior cerebral artery in males were more than that in females(χ2=5.85,P0.05).The presence rate of anterior communicating artery was 66.67% and 49.61% in posterior communicating artery(in females more than in males(χ2=6.00,P0.05).The presence rate of the fetal type and the transitional configuration posterior cerebral artery was 9.30% and 6.20%,respectively.Conclusion MSCTA is accurate for evaluating the anatomy and variation of cerebral arteries.
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Using a pulsed Doppler velocity meter, the authors assessed by a transcranial approach, in order to obtain an idea on the normal haemodynamics of the basal cerebral arteries, the maximal systolic blood flow (Vmax., m.s-1) in these arteries in a group of 25 healthy young men and in 20 healthy children. In different arteries of the two groups the following mean values of Vmax. were recorded: middle cerebral artery 0.73 +/- 0.11 parallel 0.80 +/- 0.17 m.s-1; anterior cerebral artery 0.55 +/- 0.06 parallel 0.51 +/- 0.09 m.s-1 and posterior cerebral artery 0.44 +/- 0.04 parallel 0.40 +/- 0.02 m.s-1. The assessed values of Vmax. are in agreement with data of other authors. Using the transcranial Doppler method (TD), the authors recorded in 10 children examined in the acute and subsequent stage of cerebrovascular disease recanalization of original occlusions in the anterior, middle and posterior cerebral arteries in the carotid siphon and in the basal artery and improved cerebral haemodynamics in A-V malformation in the basal ganglia. The TD method thus makes it possible to diagnose and follow up the course of these diseases. To illustrate the assessment of the function of the circle of Willis we made in three of our followed up patients with stenosis of extracranial internal carotid arteries static compression tests of both common carotid arteries. The TD method makes it possible to follow up the course of haemodynamic changes in diseases of the cerebral arteries and along with the angiographic examination it extends and supplements the evaluation of the pathological condition of the cerebral arteries and its extent.
Anterior cerebral artery
Circle of Willis
Posterior cerebral artery
Transcranial Doppler
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The purpose of this study was to assess the ability of transcranial Doppler ultrasonography to detect selective circulatory changes during cognitive activity. We measured cerebral artery flow velocity in 21 normal volunteers by transcranial Doppler ultrasonography during rest followed by cerebral activation. Mean and peak systolic flow velocities of the anterior, middle, and posterior cerebral arteries were measured during the performance of a commercial video game. We also measured flow velocity of the anterior cerebral arteries in 18 subjects during a mental arithmetic task. Serial measurements of the right and left sides were made with a headband with two probes. We observed a global increase in the flow velocity above baseline measurements during task performance. During the video game, both middle cerebral arteries (t = 2.6, p = 0.02 for the left; t = 3.3, p = 0.004 for the right) and the left posterior cerebral artery (t = 2.2, p = 0.004) had selective increase in mean flow velocity compared with the ipsilateral anterior cerebral artery. This selective activation was most prominent in the right middle cerebral artery, which had a greater degree of activation than the right posterior cerebral artery (t = 2.8, p = 0.013). We did not observe a statistically significant difference between the right and left middle cerebral arteries, but there was a trend toward a greater activation on the right for both the mean velocity (t = 1.7, p = 0.098) and the peak velocity (t = 1.9, p = 0.079). Our preliminary investigation suggests that this noninvasive technique has the potential to correlate selective cerebral artery flow dynamics with cognitive activity.
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Transcranial Doppler
Posterior cerebral artery
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To establish the usual pattern of flow in the circle of Willis in newborns, the authors scanned 53 healthy full-term infants within 3 days of birth with color Doppler imaging. All examinations were performed and images interpreted by the same experienced individuals. The basilar, internal carotid (ICA), and anterior and middle cerebral arteries were seen in all infants. Vertebral, posterior cerebral, superior cerebellar, and posterior communicating (PCoA) arteries were seen in most infants. PCoA flow was from the ICA toward the posterior cerebral artery in 73 (98.6%) of the 74 vessels that were seen. Flow in the anterior communicating artery was seen in six infants, indicating dependence of an anterior cerebral artery on contralateral ICA perfusion. Two pitfalls involving the distal portion of the ICA were noted: This vessel could be confused with the proximal portion of the anterior cerebral artery or cavernous sinus if real-time images were not interpreted carefully. Variant patterns of flow included tortuous basilar arteries (n = 2), reversed PCoA flow (n = 1), and inferior angulation of the proximal portions of the anterior cerebral arteries (n = 2). Color Doppler imaging allows a detailed analysis of the circle of Willis in newborns and detection of some anatomic variations.
Circle of Willis
Anterior cerebral artery
Posterior communicating artery
Posterior cerebral artery
Anterior communicating artery
Color doppler
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PURPOSE To provide transcranial color-coded duplex flow-velocity data for the basal cerebral arteries in patients with unilateral flow-restrictive extracranial carotid artery disease, and to compare these data with the flow velocities obtained in healthy control subjects. METHODS Transcranial color-coded duplex sonography was performed in 78 patients with different patterns of cross flow through the anterior and posterior communicating arteries associated with unilateral obstruction (70% to 100%; 46 stenoses and 32 occlusions) of the internal carotid arteries. Peak systolic, mean, and end diastolic velocities were measured in the anterior, middle, and precommunicating and postcommunicating posterior cerebral arteries. These measurements were compared with the values obtained in 125 age- and sex-matched health control subjects. RESULTS Patients with anterior communicating artery cross flow to the middle cerebral artery (63%) had increased peak velocity in the anterior cerebral artery and decrease peak velocity in the middle cerebral artery on the obstructed (ipsilateral) side, and increased peak velocity in the anterior cerebral artery on unobstructed (contralateral) side. Patients with anterior communicating artery cross flow to the pericallosal artery (19%) had increased contralateral peak systolic velocity and mean anterior cerebral artery velocities. Patients without anterior communicating artery cross flow (18%) had normal peak velocities in the anterior and middle cerebral arteries. Patients with posterior communicating artery cross flow (42%) had ipsilaterally decreased peak systolic and mean middle cerebral artery velocities and increased peak velocities in the precommunicating posterior cerebral artery. Patients without posterior communicating artery cross flow (58%) had ipsilaterally decreased peak systolic and mean middle cerebral artery velocities. CONCLUSION Our findings suggest that typical abnormalities of basal cerebral artery flow velocities occur in patients with unilateral 70% to 100% obstruction of the internal carotid arteries resulting in different patterns of cross flow through the circle of Willis.
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Anterior communicating artery
Posterior communicating artery
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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.
Anterior cerebral artery
Posterior cerebral artery
Circle of Willis
Anterior communicating artery
Posterior communicating artery
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