|Year : 2020 | Volume
| Issue : 2 | Page : 54-58
Study of pattern of origin of central branches of middle cerebral artery by using 64-slice computed tomography angiography
Mahendra Kumar Pant1, Jayanti Pant2, SK Pandey3, RC Shukla4
1 Professor, Department of Anatomy, Government Doon Medical College, Dehradun, Uttarakhand, India
2 Assistant Professor, Department of Physiology, AIIMS, Rishikesh, Uttarakhand, India
3 Former Professor, Department of Anatomy, Department of Radiodiagnosis and Imaging, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
4 Professor, Department of Radiodiagnosis and Imaging, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
|Date of Submission||07-May-2020|
|Date of Decision||22-May-2020|
|Date of Acceptance||25-May-2020|
|Date of Web Publication||10-Sep-2020|
Mahendra Kumar Pant
Department of Anatomy, Government Doon Medical College, Dehradun - 248 001, Uttarakhand
Source of Support: None, Conflict of Interest: None
Background and Aims: Middle cerebral artery (MCA), a branch of the internal carotid artery, is the most commonly affected vessel in cerebrovascular diseases. Various studies have reported for variations in the origin pattern of MCA. The detection of these variations is of clinical relevance for the clinicians for planning their line of treatment. The present study was performed to identify the variations using 64-slice computed tomography (CT) angiography. Materials and Methods: The present study was performed in 45 participants (32 males and 13 females). MCA was identified and observed for a different pattern of origin of the central (perforating) branches using 64-slice CT angiography. Results: The observations revealed that the M1 segment of MCA showed single, dual, or multiple origins of central branches. Single central branch of MCA originated in 8.88% of cases, double branches were observed in 11.11% of cases, whereas the multiple branches were found in 66.67% of cases and mix pattern was observed in 13.3% of cases. These central branches coursed through the anterior perforating substance to reach the basal area of the subcortical zone. Conclusions: The present study revealed the variations in origin of the central branches of MCA using 64-slice CT angiography and the knowledge of radiological identification of these variations can be of use for radiologists and neurosurgeons dealing with cerebrovascular diseases.
Keywords: 64 slice computed tomography angiography, anterior perforating substance, central branches, middle cerebral artery, variation
|How to cite this article:|
Pant MK, Pant J, Pandey S K, Shukla R C. Study of pattern of origin of central branches of middle cerebral artery by using 64-slice computed tomography angiography. Natl J Clin Anat 2020;9:54-8
|How to cite this URL:|
Pant MK, Pant J, Pandey S K, Shukla R C. Study of pattern of origin of central branches of middle cerebral artery by using 64-slice computed tomography angiography. Natl J Clin Anat [serial online] 2020 [cited 2020 Oct 27];9:54-8. Available from: http://www.njca.info/text.asp?2020/9/2/54/294747
| Introduction|| |
The middle cerebral artery (MCA) is one of the largest cerebral branches of the internal carotid artery (ICA). MCA originates at the bifurcation of the ICA as a direct large branch. The location of the origin of MCA is lateral to the optic chiasma and courses slightly anterolaterally and inferior to anterior perforating substance (APS) to reach the medial end of the Sylvian fissure. The MCA is divided surgically into four major branches M1, M2, M3, and M4 and distributed to the insula and the adjacent lateral cerebral surface. The M1 segment starts at the bifurcation of ICA and is also known as the sphenoidal segment. It travels parallel to the sphenoid ridge and terminates at the genu adjacent to the limen insulae, making a right turn. M2 segment also known as the insular segment, arises from genu/limen insulae or the main bifurcation and travels posterosuperiorly in the insular cleft and finally terminates at circular sulcus of the insula and makes a hairpin turn. Thereafter, the M3 segment or the opercular segment arises from the circular sulcus of the insula. This segment takes a lateral course along the frontoparietal operculum and terminates at the external/superior surface of the Sylvian fissure. From the termination point of the M3 segment, the M4 segment or the cortical segment originates and travels superiorly on the lateral convexity to terminate at their final cortical territory. The proximal segment (M1) of MCA is encountered in neurological practice very frequently as the vessel is very commonly involved in cerebrovascular diseases. Hence, understanding the anatomical features and variations specific to the proximal segment is of relevance. Studies based on the dissection of the cadaveric brain have reported for variations in anatomical patterns of the central branches originating from the M1 segment of MCA.,,, Knowledge of these variations is of great significance for the neurosurgeons., In addition to cadaveric studies, radiological identification of these variations is expected to help the clinicians in the early detection of cerebrovascular strokes in routine clinical practice. Computed tomography (CT) angiography is often used in the detection of stroke. Studies have reported use of 64-CT angiographic studies in diagnosing brain death. These studies have reported detection of MCA and its branches in their imaging observations., However, the variations of central branches of MCA by CT angiography are not reported. Hence, the present study was performed to identify the variations in origin of central branches of MCA using 64-slice CT angiography.
| Materials and Methods|| |
The study was performed after obtaining clearance from the institutional ethical committee.
The present study was an observational cross-sectional study.
The study was performed in the 64-slice CT scan center, Sir Sunderlal Hospital, a Unit of Mastel Imaging and Research center under Department of Radiology, Institute of Medical Sciences, Banaras Hindu University, India. The participants in the present study were patients who came to the Department of Radiology for CT angiography of the brain.
Data were collected from 45 patients who enrolled for CT angiography of the brain and fulfilled our inclusion criteria.
The present study was performed over the duration of 5 months from November 2009 to March 2010.
Participants who had the previous history of cerebrovascular events, neurosurgical procedures, and psychiatric disorders were excluded from the study.
CT angiography scans of participants who were enrolled for CT angiography of the brain in the department of radiology during the study period and were not having any of the diseases mentioned in exclusion criteria were used in the present study.
Informed written consent was obtained from all the participants (n = 45; males-32; females-13) in the study.
Temperature, heart rate, and blood pressure were recorded in all the participants before and after the angiography. The study participants were prepared according to standard guidelines for CT brain angiography examination. Briefly, the cases were fasted for 3–4 h before multidetector/multirow CT (MDCT) brain angiography. The participants were made to wait for half an hour before the procedure in a calm atmosphere to allay the apprehension and anxiety. All the participants were well explained about the procedure. CT brain angiography was carried out with general electric (GE) Light speed VCT 64-slice MDCT machine and adw 4.4 version advantage workstation.
The participants were asked to lie down in the supine position on the CT table. An 18 G intravenous needle was placed preferably in the right antecubital vein. The intravenous channel was connected to a dual-head pressure injector. CT brain angiography was performed on the MDCT machine using the protocol described earlier. After the anteroposterior and lateral scanograms, plain scan was also done. Scanning was performed in the caudocranial direction from thyroid cartilage up to vertex. Angiography was performed by injecting 40–60 ml (1 ml/kg body weight) of iodinated contrast medium (Omnipaque 350) at the rate of 4.5–5 ml/s followed by a saline chase of 50 ml at the same rate. The approximate volume of contrast was calculated according to the formula: V = ST × 5 (where V is volume in ml and ST is scan time in seconds). Scanning was performed during the plateau phase of vessel enhancement. The test-bolus injection method was used, in which a small amount of contrast (omnipaque 15–20 ml) was injected for synchronization.
Multiplanar reformations (MPRs), maximum intensity projections (MIPs) and volume rendering (VR) images were used for visualization. In General electric- volume computed tomography (GE-VCT) three-dimensional workstations, the images were displayed in three planes simultaneously, to allow for cross-referencing and to change the display mode on the fly. MPR images were used for the primary mode of evaluation of central branches. These images were particularly used to visualize the brain parenchyma and osseous structures in conjunction with the vessels. MIPs were created only when a specific projection was selected. VR technique was used for the integration of all available information from a volumetric data set with control of the opacity or translucency of selected tissue types.
After the procedure, the participants were observed for about 1–2 h for any delayed reactions. The participants were advised not to operate machine or drive vehicle for another 3 h after the procedure. There were no adverse reactions observed after CT angiography in any of the participants. Each central branch of MCA was analyzed for their number, origin, course, distribution, and variation if any.
Data of all the scans observed were entered into MS-Excel. Results were expressed in terms of frequency and percentage.
| Results|| |
Based on the angiographic examination, four patterns of origin of the central branches of MCA were observed. In four of the participants (males-two; females-two), a single central branch was seen to be originating from the M1 segment of MCA. The single central branch of MCA was found to ascend forward toward the APS, where it entered into the substance to form intracerebral part in the angiographic recording. Of these, the central branch was divided into two sub-central branches before piercing the APS in two participants [Figure 1] and [Table 1].
|Figure 1: (a) Volume rendering image of 64-slice computed tomography angiography showing single central branch arising from M1 segment of middle cerebral artery on both sides. (b) Coronal section of 64-slice computed tomography angiography showing the same. (c) Line diagram showing origin of single central branch (C1) from M1 segment of middle cerebral artery|
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|Table 1: Distribution of variations observed in central branches of MCA by 64-slice CT angiography in 45 patients|
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Further, in five participants (males-two, females-three), two central branches were found to be originating from the M1 segment of MCA. Both the central branches in the recording were found to be originating side by side from M1 segment and coursed anteriorly toward the APS and entered into it. In most of these recordings, both central branches at their intracerebral region were found to be united together to form an arterial arcade. The subcentral branches were seen to arise from the arterial arcade [Figure 2] and [Table 1].
|Figure 2: (a) Volume rendering image of 64-slice computed tomography angiography showing two central branches originating from M1 segment of the left middle cerebral artery to form an arterial arcade through which other central branches also originate. (b) Coronal section of 64-slice computed tomography angiography showing the same. (c) Line diagram showing the origin of two central branches (C1, C2) which form the arterial arcade|
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In 30 participants (males-24, females-6), multiple central branches were found to be originating directly from the M1 segment of MCA and all these branches were found to be piercing the APS without giving rise to any sub-central branches in their extra cerebral course. In most of these recordings, it was revealed that these multiple branches originated from the central part of the M1 segment of MCA and all the branches coursed toward the APS, and pierced in it to form their intracerebral course [Figure 3] and [Table 1].
|Figure 3: (a) Volume rendering image of 64-slice computed tomography Angiography showing multiple central branches directly arising from M1 segment of middle cerebral artery on both sides. (b) Coronal section of 64-slice computed tomography angiography showing the same. (c) Line diagram showing the origin of multiple central branches (C1, C2, C3, C4) from M1 segment of middle cerebral artery|
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In six participants (males-four, females-two), the central branches were found to be originating not only from the M1 segment of MCA but also from the other segments of MCA and even other arteries of the circle of Willis [Figure 4]. In most of these recordings, a central branch was found to be originating from the anterior cerebral artery (ACA), M1 and M2 segments of MCA separately [Figure 4]. Whereas in two cases, two central branches originated from the M1 segment, one from the M2 segment and one from the ICA, and these central branches formed an arterial network in their extracerebral course, just before entering the APS [Figure 4] and [Table 1].
|Figure 4: (a) Volume rendering image of 64-slice computed tomography angiography showing one central branch arising from anterior cerebral artery and one central branch arising from M2 and two branches from M1 segment of middle cerebral artery. All four branches are shown to anastomose in basal region of the subcortical zone to form a common trunk on both sides. (b) Coronal section of 64-slice computed tomography angiography showing the same. (c) Line diagram showing the variation in origin of the central branches of middle cerebral artery (C1–C5)|
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| Discussion|| |
The typical origin point of the central branches of MCA is the M1 segment, which are also called striatal branches.,, In the present study, four variations in the origin of these central branches were observed using 64-slice CT angiography.
Various studies have previously reported for the microsurgical and angiographic anatomy of the central branches from the M1 segment of MCA. These studies reported the presence of two groups of lenticulostriate arteries, which originated from the M1 segment of MCA, i.e., lateral and medial. Liebeskind et al. suggested that there are generally 5–17 lenticulostriate arteries, but all are not identifiable by angiography. The concept of common stems of central branches was reported previously in various studies.,,, The central branches were found to originate from the proximal segment of MCA in 96% of cases by Umansky et al., 85% of cases as reported by Aydin et al., in 97% of cases by Rosner et al., and 96% of cases by Umansky et al.,,
In the present study, it was revealed that the central branches originated not only from the M1 segment (one or two or multiple in numbers) but also from other segments of MCA and other arteries of the circle of Willis. The single central branch originated from M1 segment of MCA in 8.88 % cases (4.44% of males and 4.44% of females), double branches originated from M1 segment in 11.66% 11.11% of cases (4.44% of males and 6.67% of females) and multiple central branches were observed in 66.67% in both sexes (53.33% of males and 13.33% of females). Standring reported that central branches originated from the M1 segment in both sexes. According to Yasargil, the central branches originated from the infero-medial surface of the lateral fronto-orbital artery of the M1 segment of MCA. In the present study, the central branches originated from superiomedial surface of the M1 segment and the extra and intraparenchymal anastomoses between these branches were also observed. The origin of central branches from the main stems, or from collateral (cortical) branches of the MCA was reported in some studies., According to Liebeskind and Caplan, the lenticulostriate arteries originated from the M1 segment in the perpendicular pattern to penetrate the parenchyma of the brain., In the present study, variations in origin of these central branches were observed in 13.3% of cases (8.88% of males and 4.44% of females), in which the central branches were originated from segments other than the M1 segment of MCA and ACA. These central branches originated from the different arteries of the circle of Willis, united together to form an arterial arcade, deep to the APS. The sub-central branches originated from this arterial arcade. This pattern of variation in the origin of the central branches of the MCA might be due to the abnormal early ramification of the branches of the MCA in the embryological stage that might have occurred either proximal or distal to the origin of the main MCA trunk. Knowledge of the variations of the central branches of MCA and its extracerebral subcentral branches have their clinical implications for neurosurgeons and interventional radiologists. The lenticulostriate branches of MCA are often involved in Charcot-Bouchard aneurysms and cause cerebral hemorrhages in hypertensive patients. Noncontrast CT is one of the diagnostic modalities used to detect such hemorrhage. The variations of these branches of MCA may further pose a challenge on the clinician treating such patients. In the present study, the 64-slice CT angiography showed a substantially clear picture of some of the variations of the central branches of MCA, which may be valuable for the early detection of the pathology.
| Conclusions|| |
The present study emphasizes on the usage of 64-slice CT-angiography for the detection of variations of central branches of MCA. It can serve as a tool for microvascular imaging of the human brain and help in the early detection of cerebrovascular diseases.
The present study was performed in 64-slice CT scan center, Sir Sunderlal Hospital, BHU, Varanasi, UP, India, a unit of Mastel imaging and research center. The authors acknowledge the facilities and technical assistance of the center. The authors would like to thank Mr. Manoj Kumar Shah and Dr. K. K. Singh for their support throughout the study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]