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Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The brain is supplied with blood from two sources. The bilateral internal carotid arteries arise from the bifurcation of the common carotid arteries in the neck and branch off to form the left and right anterior and middle cerebral arteries, which supply the forebrain. The vertebral arteries arise from the subclavian arteries and come together at the level of the pons to form the midline basilar artery. The posterior cerebral, basilar and vertebral arteries supply the posterior circulation of the brain, comprising posterior cortex, the midbrain and the brainstem. Cerebellum is also supplied by dorsolateral arteries such as the posterior inferior cerebellar artery (PICA) and the anterior inferior cerebellar artery (AICA) and superior cerebellar artery. An arterial ring called the circle of Willis connects the anterior and posterior cerebral circulation; thus, in the event of loss of blood supply to one area of the brain, it may be possible for blood to be supplied via a different arterial route.
Detection of Cerebrovascular Changes Using Magnetic Resonance Angiography
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Yitzhak Gebru, Guruprasad Giridharan, Mohammed Ghazal, Ali Mahmoud, Ahmed Shalaby, Ayman El-Baz
Statistical analysis was performed using R software, version 3.3. A mixed effects linear model was used to test the relationship of MRA data with clinical BP measurements. Brain slices were separated into upper (above circle of Willis) and lower (below circle of Willis) compartments to determine correlation with clinical BP readings. The circle of Willis, near the brain base, is where the intracranial cerebral arteries take off from and give rise to progressively smaller vessels [5]. The BP measurements were combined into a single value, the estimated mean arterial pressure MAP=(2×DBP+SBP)/3, which was a covariate in the model. Also included in the model were patient age, gender, and a random intercept per patient. The dependent variable was the mean of the Euclidean distance map over the entire vascular tree within each compartment. (Two separate models were fit to the upper and lower compartments.) Statistical significance of fixed effects in the fitted models was determined using likelihood ratio chi-square tests.
Guidance for the IT Committee
Published in Maria K. Todd, Physician Integration & Alignment, 2012
In anatomy-speak, you are the “Circle of Willis” of the provider organization. For readers who are not that fluent in anatomy and physiology, the Circle of Willis is a unique vascular structure in the body that provides an extended safety net of redundancy for the brain’s blood supply. No blood, no oxygen to the brain. Everybody knows what that means. But it does not stop there. The analogy continues: the Circle of Willis, because of its complexity, varies anatomically among individuals and is a common site for congenital (present at birth) vascular anomalies (malformations of the blood vessels). Think of your subcommittees as the blood vessels. Now let me take you to a place you probably did not expect to go in this chapter.
Central arterial pressure and patient-specific model parameter estimation based on radial pressure measurements
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Dániel Gyürki, Tamás Horváth, Sára Till, Attila Egri, Csilla Celeng, György Paál, Béla Merkely, Pál Maurovich-Horvat, Gábor Halász
0D heart models can also be incorporated in these models. For example, Formaggia et al. (2006) investigated the behaviour of arterial flow using a lumped heart model. In vivo measurements were used in Reymond et al. (2009) to validate their 1D artery model with 0D heart. They also reviewed and classified different 1D arterial modelling studies. 1D artery modelling has a wide usability, for example characterizing the whole arterial system down to the arterioles (Blanco et al. 2015), investigating the volumetric flow rates of the Circle of Willis when one or more segments are missing (Zhang et al. 2016; Huang et al. 2018), or even the motion of the human body can be included like in Szabó and Halász (2017). 1D simulations may also provide boundary conditions for 3D flow simulations (Blanco et al. 2007; Józsa and Paál 2014), when a vessel malformation is present and more information is needed on the flow field.
Almost sure exponential stability of stochastic fluid networks with nonlinear control
Published in International Journal of Control, 2018
Song Zhu, Wenting Chang, Dan Liu
Consider the circle of Willis, which is a circulatory anastomosis that supplies blood to the brain and surrounding structures. As a fluid network control system, it has 10 nodes and 19 branches. We list it and it its equivalent fluid networks as in Figure 3 . Let us consider branches 11–18 and the main fan branch as the tree of the network, the constraint equations can be expressed as where Define Let Ki = 1 except K2 = 2, Ni = 1, Rar = [2, 2, 2, 1, 1, 1, 2, 2]T, Qcr = [1, 2, 1, 2, 1, 2, 1, 2, 1, 2]T, Rm = 3. From Corollary 4.1, under the initial condition QTce(0) = [0.2, −0.97, −0.4, −0.93, −0.4, −0.98, −0.64, 0.87, −0.96, 0.78] and step size Δt = 0.002, we can get the state curve of Q1e,… , Q10e and the estimate gains of and as in Figure 4 . It shows that under the controller we designed, the state Qie achieves 0, so the state Qi(t) achieves there equilibrium point Qir, i = 1,… , 10. That is to say, all the branches have reached the required flow reference values.
Central arterial pressure estimation based on two peripheral pressure measurements using one-dimensional blood flow simulation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Dániel Gyürki, Péter Sótonyi, György Paál
One of the most frequent localisation of plaque formation is on the carotid artery wall at the bifurcation, thus narrowing the lumen area. One possible solution is an open surgery when the plaque is removed from the artery, called carotid endarterectomy. The main disadvantage of this surgical intervention is the need for the clamping of the carotid arteries, which are the main suppliers of the brain. One of the reasons for the Circle of Willis (CoW), which is the most important collateral system of the brain, is to create redundancy and support the brain in the case of narrowing or blocking of the supplying arteries. However, sometimes anatomical variations in the CoW can hinder this functionality (Montisci et al. 2013; Banga et al. 2018).