Estimating the sex of cremated human remains is difficult. The petrous bone frequently survives the cremation due to its density. Wahl observed the lateral angle to be sexually dimorphic in the 1980s. Previous studies showed various cut-off points to separate females from males, which are hardly replicable and difficult to apply. We want to test the Wahl method and compare it to a new landmark-based version.
In this study, we measured the lateral angle of 35 cremated petrous bones from late bronze age Austria using micro-CT scans. Technical errors of measurement were calculated for two different methods to intersect the internal acoustic meatus virtually in the midline (manual or landmark-based intersection). Furthermore, sex was estimated based on morphological features and metric measurements. This information was used in logistic regression modeling to define a cut-off point in our sample.
The technical errors of measurement suggested that a landmark-based method was more precise in comparison to a manual intersection which was much more intuitive. Inter- and intra-observer errors were low which improved reliability. The logistic regression model produced good results in our sample (p = 0.02, R2 = 0.38, accuracy = 0.8). The mean lateral angle was similar to studies which focused on prehistoric cremated petrous bones.
The proposed landmark-based method was precise, quick, and could be easily applied, even by unexperienced researchers. The size of the lateral angle seemed to be population-specific but also dependent on the method applied. We recommend to use the proposed landmark-based method which is more precise.

BACKGROUND: From a biomechanical point of view, pedicle screws (PS) are better than other kinds of screws for implantation in the seventh cervical vertebra (C7). However, the application of PS is limited because of the high risk of severe complications. It is essential to define the optimal entry point and trajectory. The aim of this study was to comprehensively analyze the starting point and trajectory for C7 PS insertion using three dimensional (3D) models.
METHODS: Overall, 60 subjects aged 18 to 67 years old were included. All CT images were used to construct 3D computer models of the C7 vertebrae. A new coordinate system was established for the next evaluation. The pedicle axis was calculated with respect to the entire pedicle; then, the ideal entry point, screw diameter and length, sagittal angle and lateral angle were assessed.
RESULTS: All the ideal entry points were located at the medial superior to lateral notch (LN), and the mean distance between the entry point and LN was 5.86 ± 1.67 mm in the horizontal direction and 3.47 ± 1.57 mm in the vertical direction. The mean distance between the entry point and the middle point of the inferior edge of the C6 articular process (MP) was 0.74 ± 1.83 mm in the horizontal direction. The mean sagittal angle of the pedicle axis was 90.42°, and the mean pedicle transverse angle was 30.70°. The average diameter and length of the PS were 6.51 ± 0.76 mm and 31.58 ± 4.40 mm, respectively.
CONCLUSIONS: This study provided a novel method to calculate the ideal starting point and trajectory for C7 PS insertion. These measurements may be helpful for preoperative planning. It is recommended that 3D CT imaging is used preoperatively to carefully evaluate the anatomy of each individual.

OBJECTIVE: To investigate the association of middle cerebral artery (MCA) bifurcation aneurysms with bifurcation morphology.
METHODS: 205 patients were enrolled, including 61 patients with MCA bifurcation aneurysms and 144 non-aneurysmal subjects. Aneurysmal cases were divided into types C (aneurysm neck on extension of the parent artery centerline) and D (deviating neck). The radius of the parent artery M1 (RP) and bilateral branches (RS and RL, respectively), smaller (φS) and larger (φL) lateral angles, bifurcation angle, and arterial tortuosity from parent vessel to bilateral branches (TS and TL, respectively) were analyzed. Logistic regression and receiver operator characteristic (ROC) curve analysis were performed to identify risk factors and predictive values for MCA aneurysm presence and types.
RESULTS: In aneurysmal MCA bifurcations, bifurcating angle, TS, TL and RL were significantly larger (P<0.01), while φS was significantly smaller (P<0.001) than those in controls. The bifurcation angle, TS and LogitP were better morphological parameters for predicting MCA aneurysm presence with the AUC of 0.795, 0.932 and 0.951, respectively. Significant (P<0.05) differences were observed in the bifurcation angle, φL, RP, RL and TL between types C and D aneurysmal bifurcations. TL was an independent factor in discriminating types C from D aneurysms with an AUC of 0.802.
CONCLUSIONS: Bifurcation angle and arterial tortuosity from the parent artery to the branch forming a smaller angle with the parent artery have a higher value in distinguishing MCA aneurysmal from non-aneurysmal ones, and the tortuosity from the parent artery to the contralateral branch is the best indicator for distinguishing types C from D aneurysmal bifurcations.

OBJECTIVE: The aim of this study was to test the validity of a previously proposed lateral angle (LA) method for sex assessment of human skeletal remains in the forensic setting.
METHODS: Computed tomography (CT) scans of 102 crania of Greek adults were used to test the validity of the LA method for sex estimation. The measurement procedure used in this study is a modified version of a method previously proposed by Akansel et al. (2008).
RESULTS: Despite the LA values being larger for females, the difference was not found to be statistically significant. Sectioning point of 45° provided a low accuracy rate of 53 %.
CONCLUSIONS: The poor accuracy of the LA method obtained in this study proved it to be of no value in sex estimation. Future studies should examine a broader aspect of the petrous portion morphology in order to establish a more accurate method of forensic sex estimation.

Lateral angle (LA) of the internal acoustic canal (IAC) at its opening at the surface of the petrous portion of the temporal bone is known in literature as a dimorphic measurement useful for sex assessment. However, its reliability is still debated. Moreover, no information is available about the possible relationship between LA and shape and size of the IAC. This study aims at assessing breadth, length and lateral angle of IAC on 100 CT scans belonging to subjects aged between 20 and 70 years, equally divided between males and females. Possible differences in the three measurements according to side and sex were assessed through two-way ANCOVA test, using three cranial measurements (distance between anterior and posterior nasal spine, upper facial height, bizygomatic breadth) as covariates (p < 0.05). Possible correlations among IAC measurements and with age were assessed through Pearson\'s test (p < 0.05). Results showed a significantly greater IAC breadth on the left side than on the right side; moreover, LA was significantly wider in females than in males and was positively correlated with IAC breadth in both males and females. In addition, LA was negatively correlated with age only in the female group. The study first showed that LA is strictly related to IAC morphology; moreover, it is significantly affected by masculinization of skeletal traits in females. Therefore, caution is suggested in using this measurement for sex assessment.

The lateral angle of the internal acoustic canal is one of the measurements of petrous bone that has been previously studied for sex estimation, mostly in adults. We aimed at evaluating the effects of age, side, and sex on the lateral angle of the internal acoustic canal in pediatric patients. Pediatric routine cranial MRI studies were retrospectively investigated for this study. The lateral angle was measured on T2-weighted axial images when the anterior and posterior lips of the meatus and the cochlea were clearly visible on the same image. The data were evaluated for age, side and sex-related changes. Although 552 temporal bones from 273 patients were inspected, due to exclusion criteria lateral angle could be satisfactorily measured only in 101 temporal bones from 58 patients. The measurements did not differ significantly between sexes. An age-related, statistically significant decrease was observed for the entire pediatric sample studied, as well as for the males, but not for females. The measurements did not differ from side to side. The significant age-related decrease in lateral angle in male pediatric patients that was not detected in female counterparts may be the reflection of a sex-related difference in temporal bone development during childhood. Routine cranial MRI data may help investigators study age and sex-related changes in lateral angle in children.

This article presents the results of a validation study of a previously published method of sex determination from the temporal bone. The purpose of this study was to evaluate the lateral angle method for the internal acoustic canal for accurately determining the sex of human skeletal remains using measurements taken from computed tomography (CT) scans. Previous reports have observed that the lateral angle size in females is significantly larger than in males. The method was applied to an independent series of 77 postmortem CT scans (42 males, 35 females) to validate its accuracy and reliability. The mean lateral angle of the internal acoustic canal was found to be larger in females (46.5°) than in males (43.4°). However, the difference was not statistically significant and the sex differences reported in previous studies were not substantiated. In light of the observed results, the lateral angle method appears to be of minimal practical use in forensic anthropology and archeology.