An anatomic study of the horizontal petrous internal carotid artery: Sex and age differences

Morphometry of the Entire Internal Carotid Artery on CT Angiography

Background and Objectives: Knowledge of the internal carotid artery’s (ICA) morphometric features is influential in outlining surgical and minimally invasive procedures in the neurovascular field. Many studies have shown divisive numbers regarding the ICA’s caliber, with the measuring point of the artery sometimes differing. This study presents ICA dimensions based on computed tomography angiography in each of its seven segments as per Bouthillier’s classification, correlating vascular dimensions with anthropometric parameters. Materials and Methods: A thorough CT angiography analysis was performed on 70 patients with internal carotid vessels unaffected by atherosclerotic disease. The extracranial part of the ICA was measured in four locations—carotid bulb, post-bulbar dilation, at its cervical midpoint, and below its entrance into the carotid foramen. Single landmarks were used for measurements in the intracranial segments. ICA length was assessed in the neck region and also in the cranial cavity. Craniometric measurements were performed on sagittal and coronal CT reconstructions. Patient height was taken into consideration. Results: The largest ICA portion is near its origin in the carotid sinus area (7.59 ± 1.00 mm), with a steep decline in caliber following its extracranial course. Distal ICA presented values somewhat similar to its proximal intracranial segment diameters (4.67 ± 0.47 mm). Dimensions of the ICA in the intracranial segments start from a value of 4.53 ± 0.47 mm and decrease by approximately 40% when reaching the origin of the middle cerebral artery (2.71 ± 0.37 mm), showing a marked decrease in caliber after the emergence of the most critical collateral artery, the ophthalmic branch. The length of the ICA varies between genders, with the male ICA being about 10 mm longer in total length than female ICA; this difference is also correlated with patient height and skull dimensions. Conclusions: Both intra- and extracranial ICA have variable dimensions and length related to gender and anthropometric parameters, with no significant differences obtained concerning side or age.

Important landmarks and distances for posterior fossa surgery measured by temporal MDCT

In this retrospective study, we aimed to present important anatomical structures and distances for posterior fossa surgery by temporal multidetector computed tomography (MDCT). The temporal MDCT images of 317 adult patients (158 males and 159 females) were retrieved from the hospital's picture archiving and communication system (PACS). In the coronal temporal MDCT views, the cochlea-carotid canal and jugular bulb-mastoid bone outer surface were measured. In the axial MDCT views, the carotid canal-jugular bulb and carotid canal-posterior fossa distances were measured; the carotid canal and jugular bulb anterior-posterior (AP) and transverse dimensions were also measured. The bilateral cochlea-carotid canal, jugular bulb-mastoid bone outer surface, and right carotid canal-jugular bulb distances were significantly greater in the males than those in the females (p < 0.05). The carotid canal-posterior fossa distance was not different in both genders (p > 0.05). The carotid canal-jugular bulb and the carotid canal-posterior fossa distances were greater on the left side than those on the right side in both genders (p < 0.05). In males, the outer surface distance was greater on the left jugular bulb-mastoid bone than that on the right side of that bone (p < 0.05). The difference between the carotid canal AP dimensions was not significant between males and females (p > 0.05). However, the carotid canal transverse dimension, jugular bulb AP, and transverse dimensions were significantly greater in the males than those in the females, bilaterally (p < 0.05). In each gender separately, the carotid canal AP and transverse dimensions were greater on the left side and the jugular bulb AP and transverse dimensions were greater on the right side than those on the left side (p < 0.05). Positive correlations were found between the cochlea-carotid canal, the jugular bulb-mastoid bone outer surface, and the carotid canal-jugular bulb distances as well as between the jugular bulb-mastoid bone outer surface and the carotid canal-posterior fossa distances (p < 0.05). In older patients, the carotid canal-posterior fossa distances were shorter on the left side (p < 0.05). Vascular and neural localizations should be well understood in the operative area before applying the surgical approach in the posterior fossa. Computed tomography (CT) has a greater role in the evaluation of bone structures and vascular canals in this area.

Morphometric Analysis of Greater Palatine Canal via Cone-Beam Computed Tomography

Background/Aim: The morphology of the greater palatine canal (GPC) should be determined preoperatively to prevent possible complications in surgical procedures required maxillary nerve block anesthesia and reduction of descending palatine artery bleeding. The purpose of this investigation was to evaluate the GPC morphology.

Material and Methods: In this retrospective cross-sectional study, cone-beam computed tomography images obtained for various causes of 200 patients (females, 55%; males, 45%) age ranged between 18 and 86 (mean age±standard deviation=47±13.6) were examined. The mean length, mean angles of the GPC and anatomic routes of the GPC were evaluated.

Results: The mean length of the GPC was found to be 31.07 mm and 32.01 mm in sagittal and coronal sections, respectively. The mean angle of the GPC was measured as 156.16° and 169.23° in sagittal and coronal sections. The mean angle of the GPC with horizontal plane was measured as 113.76° in the sagittal sections and 92.94° in the coronal sections. The mean GPC length was longer in males than in females.

Conclusions: The results of this study showed that the most common pathway of the GPC was “first inferior, and then anterior-inferior direction” in sagittal plane and “first medial-inferior, then inferior direction” in coronal plane.

Anatomic Characteristics of Intrapetrous Carotid Artery: A 3-Dimensional Segmentation Study on Head Computed Tomography Scan

BACKGROUND

The intrapetrous carotid artery (IPCA) is one of the most unexplored anatomic regions, and its 3-dimensional reconstruction in living subjects is still missing. This study aims to describe the IPCA on 3D models extracted from head computed tomography (CT) scans.

METHODS

The intrapetrous carotid artery was manually segmented on head CT scans of 100 healthy patients free from vascular and neurologic pathologies (50 men and 50 women; age range, 18-91 years). Angles of the posterior and anterior genu, diameter and length of the horizontal portion, and volume of the entire canal were calculated through 3D analysis software. Statistically significant differences according to sex and side were assessed through 2-way analysis of variance (P < 0.05). Correlation of each measurement with age was calculated as well.

RESULTS

On average, the angles of the posterior and anterior genu were 120.1° ± 10.4° and 118.0° ± 10.0° in men and 119.5° ± 9.2° and 117.6° ± 10.3° in women, respectively, without statistically significant differences according to sex or side (P > 0.05). The average length and diameter of the horizontal part were, respectively, 25.5 ± 2.9 and 5.8 ± 0.8 mm in men and 24.0 ± 2.3 and 5.3 ± 0.8 mm in women. The volume of the IPCA was 0.941 ± 0.215 cm³ in men and 0.752 ± 0.159 cm³ in women. The length and diameter of the horizontal portion and the volume of the IPCA showed statistically significant differences according to sex (P < 0.05). No correlation with age was found.

CONCLUSIONS

This study provides data concerning not only linear and angular measurements, but also volumes of the IPCA, which are useful in planning surgical interventions of the cranial base.

Anatomical study of petrous and cavernous parts of internal carotid artery

The petrous and cavernous parts of internal carotid artery (ICA) are obscure and are not readily accessible to observation/imaging. These parts have broad biological and medical interest because of their peculiar shape. Given the their clinical importance and the scarce data available based mostly on imaging, the present study was aimed at studying these parts of ICA by dissection. The study was carried out on 56 ICAs obtained from embalmed adult cadavers and 10 ICAs from five fetuses. The foetal ICAs were studied in situ. The morphometric analysis of the adult ICA was done after its removal from cranial cavity to gain an insight into the geometry of the vessel, i.e., length, various bends, and diameters at various locations. ICAs in fetuses ran a relatively straighter course taking gentle curves at three positions (two intrapetrous, one cavernous). Adult ICAs were more tortuous and exhibited greater variability in length and angulations. The length of respective portions of the ICA correlate negatively with the measure of angles. The angles in the petrous and cavernous parts were positively correlated to each other. The carotid siphon was positively, highly significantly correlated to other angles. Longer vessels are more tortuous with acute bends. An acute carotid siphon is an indication of more tortuous ICA. The findings of the present study have created a reference data of unsuspected adult population and has potential implications for studying cause/effect relationship of vessel geometry and hemodynamic factors.

Design of a multifiber light delivery system for photoacoustic-guided surgery

This work explores light delivery optimization for photoacoustic-guided minimally invasive surgeries, such as the endonasal transsphenoidal approach. Monte Carlo simulations were employed to study three-dimensional light propagation in tissue, comprising one or two 4-mm diameter arteries located 3 mm below bone, an absorbing metallic drill contacting the bone surface, and a single light source placed next to the 2.4-mm diameter drill shaft with a 2.9-mm diameter spherical drill tip. The optimal fiber distance from the drill shaft was determined from the maximum normalized fluence to the underlying artery. Using this optimal fiber-to-drill shaft distance, Zemax simulations were employed to propagate Gaussian beams through one or more 600 micron-core diameter optical fibers for detection on the bone surface. When the number of equally spaced fibers surrounding the drill increased, a single merged optical profile formed with seven or more fibers, determined by thresholding the resulting light profile images at 1 / e times the maximum intensity. We used these simulations to inform design requirements, build a one to seven multifiber light delivery prototype to surround a surgical drill, and demonstrate its ability to simultaneously visualize the tool tip and blood vessel targets in the absence and presence of bone. The results and methodology are generalizable to multiple interventional photoacoustic applications.

Analysis of the greater palatine foramen in a Lebanese population using cone-beam computed tomography technology

Objective:

The aim of this study was to describe the diameter and the position of the greater palatine foramen (GPF) in relation to adjacent anatomical landmarks in the maxilla in a Lebanese population using cone-beam computed tomography (CBCT) technology.

Materials and Methods:

CBCT images of 58 Lebanese adult patients were included in this study and a total of 116 GPF were evaluated bilaterally. The diameter of the GPF and its position relative to the maxillary molars, and distances to the midline maxillary suture and to the anterior nasal spine were analyzed.

Results:

Of all foramina assessed, 41.38% were located opposite to the third molar, 29.31% were distal to it, 27.59% were between the second and the third, and only 1.72% were opposite to the second. The average diameter was 5.633 mm on the right and 5.723 mm on the left, and the average distances to midline maxillary suture and anterior nasal spine were 16.228 mm and 48.294 mm on the right and 14.907 mm and 48.122 mm on the left, respectively.

Conclusion:

Within the limits of this study, we conclude that in Lebanese patients, the GPF location is variable, very rarely opposite to the second molar, and more closely related to the third, but may present mesial or distal to it in one-fourth of patients.

Localization of Transcranial Targets for Photoacoustic-Guided Endonasal Surgeries

Neurosurgeries to remove pituitary tumors using the endonasal, transsphenoidal approach often incur the risk of patient death caused by injury to the carotid arteries hidden by surrounding sphenoid bone. To avoid this risk, we propose intraoperative photoacoustic vessel visualization with an optical fiber attached to the surgical tool and an external ultrasound transducer placed on the temple. Vessel detection accuracy is limited by acoustic propagation properties, which were investigated with k-Wave simulations. In a two-layer model of temporal bone (3200 m/s sound speed, 1-4 mm thickness) and surrounding tissues, the localization error was ≤2 mm in the tranducer's axial dimension, while temporal bone curvature further degraded target localization. Phantom experiments revealed that multiple image targets (e.g. sphenoid bone and vessels) can be visualized, particularly with coherence-based beamforming, to determine tool-to-vessel proximity despite expected localization errors. In addition, the potential flexibility of the fiber position relative to the transducer and vessel was elucidated.

Length and anatomic routes of the greater palatine canal as observed by cone beam computed tomography

BACKGROUND

Greater palatine canal is used for maxillary nerve block. This procedure has some complications such as proptosis, blindness, and intravascular injection. This study aimed to determine the mean greater palatine canal length (CL) and its typical anatomic routes, as well as provide a reliable facial index for computing the CL by using cone beam computed tomography (CBCT) data.

MATERIALS AND METHODS

A total of 138 CBCT scans (65 females and 73 males) were evaluated. The path of the canal and the CL were determined by sex, age, and side. The mean distance from the inferior border of the infraorbital foramen (IOF) to the crest of alveolar bone between maxillary premolar(CMP) was measured and compared with the CL. Paired t-tests, independent t-test, and one-way analysis of variance (ANOVA) were used for statistical analysis.

RESULTS

The mean of CL was 31.82 ± 1.37 mm (31.70 ± 2.44 mm on the right side and 31.94 ± 2.40 mm on the left side), and the values were 32.49 ± 2.37 mm in males and 30.55 ± 1.76 mm among females (P = 0.001). The mean distance from the IOF to the CMP was 32.01 ± 2.18 mm, which was not significantly different to the CL (P = 0.336).

CONCLUSIONS

The mean CL was significantly different according to sex and side. The mean distance from the IOF to CMP was significantly different according to sex. On comparing the mean distance from the IOF to the CMP with the CL, no significant difference was observed. Therefore, the mean distance from the IOF to CMP may be a reliable clinical index.

Aplasia and displacement of the horizontal portion of the petrous carotid artery in mandibulofacial dysostosis

CONCLUSIONS

The horizontal portion of the petrous carotid artery (HPCA) of mandibulofacial dysostosis (MFD) patients had anterior-inferior displacement or was aplasia at birth. Our findings indicate that most MFD patients have aplasia of the internal carotid artery. This information may be very important for safe reconstruction surgery in atresia.

OBJECTIVE

MFD rarely has malformations of the cardiovascular system such as those seen in Goldenhar syndrome. This study aimed to compare MFD patients and normal subjects with respect to the length and diameter of the HPCA.

SUBJECTS AND METHODS

We radiographically studied 22 MFD patients (44 sides) using high-resolution computed tomography (HRCT), measuring the length and diameter of the HPCA and the angle between the right and left HPCA using computer software. Findings were compared with those in 86 ears with normal auricles (control group) using the nonparametric test.

RESULTS

The HPCA in MFD patients averaged 23.2 mm in length and 4.8 mm in diameter. The angle between the right and left HPCA averaged 100.2 degrees. In MFD patients, on average, HPCA were 2.0 mm shorter (p=0.001) and 0.4 mm narrower (p=0.016) than in control subjects. Mean angle between right and left HPCA was 5.4 degrees more acute in MFD patients than in control subjects (p=0.026). Moreover, the genu of the vertical and horizontal petrous ICA in the MFD group was on average 3.2 mm more inferior than in controls (p<0.001).