Size, course, distribution and anomalies of the middle cerebral artery in adult Nigerians

Flow in temporally and spatially varying porous media: a model for transport of interstitial fluid in the brain

Flow in a porous medium can be driven by the deformations of the boundaries of the porous domain. Such boundary deformations locally change the volume fraction accessible by the fluid, creating non-uniform porosity and permeability throughout the medium. In this work, we construct a deformation-driven porous medium transport model with spatially and temporally varying porosity and permeability that are dependent on the boundary deformations imposed on the medium. We use this model to study the transport of interstitial fluid along the basement membranes in the arterial walls of the brain. The basement membrane is modeled as a deforming annular porous channel with the compressible pore space filled with an incompressible, Newtonian fluid. The role of a forward propagating peristaltic heart pulse wave and a reverse smooth muscle contraction wave on the flow within the basement membranes is investigated. Our results identify combinations of wave amplitudes that can induce either forward or reverse transport along these transport pathways in the brain. The magnitude and direction of fluid transport predicted by our model can help in understanding the clearance of fluids and solutes along the Intramural Periarterial Drainage route and the pathology of cerebral amyloid angiopathy.

Anatomical Variations and Anomalies of the Middle Cerebral Artery

OBJECTIVE

Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all the variations and anomalies within the middle cerebral artery (MCA).

METHODS

PubMed was searched with the MeSH-term "Middle Cerebral Artery." Articles were selected based on their description of variants within the MCA. Cross-referencing was used to broaden the range of articles. The anatomical variants were then schematically drawn using the anteroposterior and lateral view during angiography of the internal carotid artery.

RESULTS

A total of 29 unique medical illustrations were made, depicting variation in number of vessels; variation in vessel origin; and variation in morphology.

CONCLUSIONS

The MCA provides vital blood supply to the frontal, parietal, temporal, and central brain structures. An overview of these variations is important to diagnose and treat patients with MCA-related pathology correctly and safely. They can aid in distinguishing pathology from normal anatomical variance; aid neurosurgeons during aneurysmal clipping or arteriovenous malformation resections; and aid interventional radiologists during thrombectomy or coiling. This article provides a summary regarding current knowledge of anatomical variations within the MCA, their prevalence and clinical relevance. A total of 29 unique illustrations were made, depicting currently known variants. We encourage all who diagnose, treat, and study the MCA to use this overview for a uniform and better understanding of its anatomy.

Assessment of morphometric parameters of middle cerebral artery using CT angiography in a tertiary care hospital

PURPOSE

Middle cerebral artery (MCA) favors secondaries and emboli deposition. Also, with an increase in incidence of MCA aneurysms, majorly at the M1 division point, actual standardized measurement of MCA is necessary. Thus, main aim of the study is assessment of the MCA morphometry using CT Angiography in Indian population.

METHODS

CT cerebral Angiography datasets of 289 patients (180 males and 109 females) were assessed for the MCA morphometry (Average age - 49.29 ± 16.16 years, Range- 11 to 85 years). The cases involving aneurysms and infarcts were excluded. The total length of MCA, length of M1 segment and diameter were measured and the results were statistically analysed.

RESULTS

The mean total length of MCA, length of M1 segment and diameter were 24.02 ± 1.22 mm, 14.32 ± 1.27 mm, 3.33 ± 0.62 mm, respectively. The mean length of M1 segment on the right and left sides was 14.19 ± 1.39 mm and 14.44 ± 1.12 mm, respectively and the difference was statistically significant (p ≤ 0.05). The mean diameter on the right and left sides was 3.32 ± 0.62 mm and 3.33 ± 0.62 mm, respectively and the difference was not statistically significant (p = 0.832). The M1 segment length was maximum in patients over 60 years and diameter was maximum in young patients (20-40 years). The mean length of M1 segment in early bifurcation (4.4 ± 0.65 mm), bifurcation (14.32 ± 1.27 mm) and trifurcation (14.15 ± 1.43 mm) was also noted.

CONCLUSION

The MCA measurements will be useful for surgeons to minimize errors in handling cases of intracranial aneurysms or infarcts and provide the best possible outcome to the patients.

Assessment of thrombus using susceptibility-weighted filtered-phase images in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Recognizing the location and length of the thrombus responsible for large vessel occlusion in patients with acute ischemic stroke can facilitate effective endovascular recanalization therapy (ERT). We hypothesized that the aliasing or dipole effect produced by filtered-phase susceptibility-weighted imaging (SWI) would facilitate thrombus delineation.

METHODS

Of the patients with middle cerebral artery occlusion who underwent ERT, we screened those who underwent noncontrast CT (NCCT), multiphase CT angiography (mCTA), and SWI before the endovascular procedure. We used an arbitrary index termed measurement of equivalence in thrombus assessed by digital subtraction angiography (METAD) defined as having the same location as the thrombus observed in the digital subtraction angiography (DSA) and length differing by less than 5 mm. For NCCT, mCTA, SWI_m (magnitude), and SWI_p (phase), the length of the thrombus and METAD were assessed.

RESULTS

The mean lengths of the thrombi determined using NCCT, mCTA, SWI_m, SWI_p, and DSA were 14.03, 13.47, 13.89, 9.93, and 8.96 mm, respectively. The absolute agreement for thrombus length was excellent for SWI_p and DSA (intraclass correlation coefficient [ICC] = .96), moderate for SWI_m and DSA (ICC = .53), and poor for mCTA and DSA (ICC = .14). The METADs were 26.7%, 40.0%, 33.3%, and 73.3% for NCCT, mCTA, SWI_m, and SWI_p, respectively. The METADs for NCCT and SWI_p were significantly different (p = .045) and those for mCTA and SWI_m were not (p = .537 and .093, respectively).

CONCLUSIONS

The SWI_p was best matched with the DSA for the measurement of the lengths and locations of thrombi. The use of pre-thrombectomy SWI_p imaging for acute ischemic stroke may facilitate a successful ERT strategy.

Modelling and simulation of fluid flow through stenosis and aneurysm blood vessel: a computational hemodynamic analysis

In this article, the hemodynamics of nanofluid flow through the modelled stenosis-aneurysm models in the presence of the catheter has been studied. The eight stenosis-aneurysm models are developed to mimic biological observations and thus make the model more realistic. The mathematical understanding helps in treating the stenosis in the blood vessel by targeting the unhealthy region to the drug, which is coated on nanoparticles. The catheter achieves the active drug release to the aimed organs by coating on the catheter surface, which adds additional benefits. In the present hemodynamic study, the blood is modeled as a couple stress fluid; as a result, the highly non-linear momentum, temperature, and concentration equations were obtained. The fluid flow equations' complexity is further increased by incorporating the variable viscosity effects that arose due to the suspension of nanoparticles. The resultant mathematical model is solved by using the homotopy perturbation method. The convergence of the perturbed solutions is studied and depicted the degree of deformation in the case of temperature and concentration. The effects of the porous nature of the stenosis, no-slip at the catheter surface, and the free slip at the blood vessel boundary in the non-stenotic region are also considered in the model. The essential physiological property like surface shear stress is computed, and various parameters' influence on shear stress is analyzed. The present analysis can be helpful in understanding the enhancement in mass dispersion and heat transfer in unhealthy blood vessels, which could be used for drug delivery in the treatment of stenotic conditions.

Quantitative time-of-flight MR angiography for simultaneous luminal and hemodynamic evaluation of the intracranial arteries

PURPOSE

To report a quantitative time-of-flight (qTOF) MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries.

METHODS

Implemented using a thin overlapping slab 3D stack-of-stars based 3-echo FLASH readout, qTOF was tested in a flow phantom and for imaging the intracranial arteries of 10 human subjects at 3 Tesla. Display of the intracranial arteries with qTOF was compared to resolution-matched and scan time-matched standard Cartesian 3D time-of-flight (TOF) MRA, whereas quantification of mean blood flow velocity with qTOF, done using a computer vision-based inter-echo image analysis procedure, was compared to 3D phase contrast MRA. Arterial-to-background contrast-to-noise ratio was measured, and intraclass correlation coefficient was used to evaluate agreement of flow velocities.

RESULTS

For resolution-matched protocols of similar scan time, qTOF portrayed the intracranial arteries with good morphological correlation with standard Cartesian TOF, and both techniques provided superior contrast-to-noise ratio and arterial delineation compared to phase contrast (20.6 ± 3.0 and 37.8 ± 8.7 vs. 11.5 ± 2.2, P < .001, both comparisons). With respect to phase contrast, qTOF showed excellent agreement for measuring mean flow velocity in the flow phantom (intraclass correlation coefficient = 0.981, P < .001) and good agreement in the intracranial arteries (intraclass correlation coefficient = 0.700, P < .001). Stack-of-stars data sampling used with qTOF eliminated oblique in-plane flow misregistration artifacts that were seen with standard Cartesian TOF.

CONCLUSION

qTOF is a new 3D MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries that provides significantly greater contrast-to-noise ratio efficiency than phase contrast and eliminates misregistration artifacts from oblique in-plane blood flow that occur with standard 3D TOF.

Variable Anatomy of the Middle Cerebral Artery from Its Origin to the Edge of the Sylvian Fissure: A Direct Fresh Brain Study

The middle cerebral artery (MCA) is a major artery supplying blood to the brain and a common site of surgically treatable intracranial aneurysms. The MCA has anatomic variations that may have clinical significance. In order to investigate and document the extent of such variations, the MCA in 100 fresh brain hemispheres from 50 deceased patients, obtained from the Police Surgeon Office, Yangon General Hospital, Myanmar, was dissected and examined. Double MCA was observed in 2% of specimens. The termination patterns were bifurcation (72%), trifurcation (16%), and primary trunk (12%); early bifurcation was also observed (3%). The mean length of the main trunk (MT) was 20.6 ± 6.2 mm. The number of perforators ranged from 4 to 15 (mean = 9); most arose from the MT (96%), and the others originated at the bifurcation point (3%) and in postbifurcation divisions (1%). All of the perforators (100%) had a single branching pattern. The number of cortical branches ranged from 6 to 13 and included the orbitofrontal (98%), prefrontal (99%), precentral (95%), central (98%), temporopolar (87%), anterior temporal (89%), middle temporal (24%), posterior temporal (62%), temporo-occipital (69%), anterior parietal (88%), angular (83%), and posterior parietal (57%) arteries. Early cortical branches emerged from the MT in 52% of specimens. These data can help anatomists, radiologists, and neurosurgeons in preoperative assessment, surgical planning, and selection of surgical approach.

Study of Middle Cerebral Artery in Human Cadaveric Brain

Background:

Middle cerebral artery (MCA) is the larger terminal branch of the internal carotid artery. It travels through the Sylvian fissure on the insula.

Objective:

MCA supplies a large area of distribution than the other two cerebral arteries. Though it is so, there are very few articles in the literature describing MCA. Aim of the present work is to study the MCA regarding its origin, course, termination, branching pattern, morphometry and symmetry.

Materials and Methods:

340 MCAs from 170 formalin preserved brains were dissected. Morphology, morphometry and symmetry of MCAs, were studied in detail and well photographed. The data collected in the study was analyzed.

Results:

Accessory MCA was found in seven specimens (2.05%). Duplicated MCA was seen in three specimens (0.88%). Aneurysm was found in three specimens (0.88%). MCA with bifurcated, trifurcated, quadrifurcated and single trunk termination was seen in 220 (64.70%), 42 (12.35%), 8 (2.35%), and in 70 (20.58%) specimens respectively. Bifurcated pattern as upper prominent trunk (type A), lower prominent trunk (type B) and both equal prominent trunks (type C) were seen in 63 (28.63%), 129 (58.63%), and 28 (12.72%) specimens respectively. Asymmetry was seen in 102 specimens (60%). Mean length and diameter of the MCA was 25.5-27.8 mm and 3 mm respectively.

Conclusion:

Awareness of these anatomical variations in branching patterns is important in neurovascular procedures. As very few Anatomical studies on MCA are there in the literature, this type of research work should be done by a number of scientists from a different region of the world in large scale.

Branching pattern of middle cerebral artery in an African population

Branching pattern of middle cerebral artery influences frequency of its aneurysms, and is of potential value in their surgical repair and diagnosis of stroke. This pattern shows inter-population variations but there is paucity of data from Africans. This study aimed at describing branching pattern among black Kenyans. Middle cerebral arteries numbering 288 from 144 formalin fixed brains obtained during dissection and autopsy at Department of Human Anatomy, University of Nairobi, Kenya were studied. Origin of the middle cerebral artery was identified at base of brain and its stem followed by gently separating the fronto-parietal and temporal lobes. Pattern of early cortical, lenticulostriate, and terminal branching was recorded and macrographs taken. Results were analyzed using SPSS version 13.0 for windows and presented using macrographs. All the brains had bilateral middle cerebral arteries which were continuations of the internal carotid artery. Variations of the artery observed included duplication (1.7%), early bifurcation (5.2%), and early cortical branching (47%), predominantly temporal (63.9%). Lenticulostriate arteries arose predominantly from the pre-bifurcation segment as single branches (64.6%), and as common trunks (35.4%). Modes of termination were bifurcation (82.3%), trifurcation (10.8%), primary trunks (6.2%), and quadrifurcation (0.7%). Cortical branching pattern of the middle cerebral artery resembles that of Caucasian and Indian populations suggesting equal vulnerability to aneurysms and stroke. Pattern of origin of lenticulostriate arteries, predominantly from the pre-bifurcation segment and higher percentage of common trunks implies that the population is more prone to ischemia after aneurysm repair. Extra diligence during operation on proximal middle cerebral artery is called for.

Development and validation of models for the investigation of blood clotting in idealized stenoses and cerebral aneurysms

An in vitro model of blood clotting is presented using hypercoaguable milk as an analog for blood. Milk clot formation was studied for periods of 2, 5, 10, 20, and 30 min within an idealized stenosis geometry. Clot formation was recorded using photography, clot casting, and clot mass calculation. The distribution of clot within the fluid was seen to be in good agreement with a previous study that used a residence time model to predict areas of clot formation in thrombin solution. A numerical model was formulated within computational fluid dynamics package CFX that allowed local activation of blood clotting to be simulated. This model was applied to the analysis of an idealized cerebral aneurysm geometry. An idealized coil geometry was included within the aneurysm and clotting fluid concentration and fluid residence time were modeled using transport equations within CFX. The viscosity of the fluid was defined as a function of both residence time and clotting fluid concentration. The model was seen to produce features consistent with observations of thrombosis within cerebral aneurysms, while avoiding the unrealistic build up of clot in near-wall regions that is associated with a pure residence time model.