Preoperative diffusion tensor imaging: Fiber-trajectory-distribution-based tractography to identify facial nerve in vestibular schwannoma.

PURPOSE: Tractography of the facial nerve based on diffusion MRI is instrumental before surgery for the resection of vestibular schwannoma, but no excellent methods usable for the suppression of motion and image noise have been proposed. The aim of this study was to effectively suppress noise and provide accurate facial nerve reconstruction by extend a fiber trajectory distribution function based on the fourth-order streamline differential equations. METHODS: Preoperative MRI from 33 patients with vestibular schwannoma who underwent surgical resection were utilized in this study. First, T1WI and T2WI were used to obtain mask images and regions of interest. Second, probabilistic tractography was employed to obtain the fibers representing the approximate facial nerve pathway, and these fibers were subsequently translated into orientation information for each voxel. Last, the voxel orientation information and the peaks of the fiber orientation distribution were combined to generate a fiber trajectory distribution function, which was used to parameterize the anatomical information. The parameters were determined by minimizing the cost between the trajectory of fibers and the estimated directions. RESULTS: Qualitative and visual analyses were used to compare facial nerve reconstruction with intraoperative recordings. Compared with other methods (SD_Stream, iFOD1, iFOD2, unscented Kalman filter, parallel transport tractography), the fiber-trajectory-distribution-based tractography provided the most accurate facial nerve reconstructions. CONCLUSION: The fiber-trajectory-distribution-based tractography can effectively suppress the effect of noise. It is a more valuable aid for surgeons before vestibular schwannoma resection, which may ultimately improve the postsurgical patient's outcome.

Establishment of Cephalic Index by Computed Tomography in Sampled Chinese Children.

OBJECTIVE: Cephalic Index (CI), the ratio of head width to length, is one of the indexes reflecting cranial morphological characteristics. Current norms were established by European and American countries. The purpose of the study was to study anthropometry of cranial parameters using computed tomography scans to establish the CI of the sampled Chinese Children. METHODS: The cross-sectional study was carried out on patients of age younger than 14 years old at Shanghai Children's Medical Center. The measurement of maximum cranial breadth and maximum cranial length were taken on a computed tomography scan machine and recorded for analysis. Cephalic Index was calculated for each age and sex group and compared with previously established norms. RESULTS: Five hundred eighteen patients met the inclusion criteria, including 301 males and 217 females. The means for boys and girls were 87.1 (SD: 4.3) and 85.8 (SD: 4.3), respectively. There was a significant difference between boys and girls (P < 0.01). Cephalic Index in different ages and on applying the 1-way analysis of variance association was statistically insignificant (P = 0.19). CONCLUSIONS: Chinese head shape was brachycephalic. A statistically significant correlation was seen between the CI and sex, while not age.

Experimental study on the strain energy evolution mechanism of thick and hard sandstone roof in Xinjiang Mining Area.

For understanding the mechanical performance and strain energy evolution mechanism of thick hard roof sandstone samples, a sequence of uniaxial compression trials with acoustic emission (AE) monitoring were carried out. The results indicate: (1) The stress-strain curve of the thick hard roof sandstone specimens exhibits distinct stage characteristics. Based on the evolvement of instantaneous axial stiffness, it is separated into Fracture Closure Phase, Elastic Deformation Phase, Steady Fracture Expansion Phase, Unsteady Fracture Expansion Phase, and Post-Peak Phase. (2) The AE energy and cumulative count curves of the thick hard roof sandstone specimens also exhibit significant stage characteristics and can be mutually corroborated with the stage division of the stress-strain curve. (3) Based on the energy conservation principle, the evolution of strain energy density in the thick hard roof sandstone specimens under uniaxial compression loading was analyzed, and plastic strain energy increment was employed to study the stage characteristics of strain energy dissipation. (4) A damage constitutive model for the thick hard roof sandstone specimens was constructed, considering the characteristics of strain energy dissipation. This model effectively describes the stress-strain relationship among the samples, which undergo strain hardening, strain softening, and sudden destruction.

Constricted posterior fourchette deformities: Definition, classification and surgical treatment.

BACKGROUND: Labiaplasty is one of the top cosmetic procedures patients are seeking in the past two years. However, treatment of disease in posterior fourchette caused by various etiological factors was less investigated and neglected. METHODS: Three types of posterior fourchette deformity were proposed: (1) Redundant posterior fourchette, (2) Relaxed posterior fourchette, and (3) Constricted posterior fourchette. Local flap transfer technique was applied. Y-V-plasty and 5-Z-Flap-plasty were used to treat web type and tight type of the constricted posterior fourchette, respectively. Follow-ups were arranged on the Internet or at the outpatient clinic. Visual analogue scale (VAS) was utilized to evaluate sexual discomfort in the satisfaction questionnaires during follow-up. RESULTS: A total of 48 patients with constricted posterior fourchette deformity from May 2022 to May 2023 were reviewed in the study. Y-V-plasty could decrease VAS in patients with web-type deformity by 4.13 ± 1.46 (p＜0.001). 5-Z-Flap-plasty could decrease VAS in patients with tight-type deformity by 3.76 ± 1.53 (p＜0.05). Satisfaction rates of the web type and tight type were 93.1% (27/29) and 86.7% (13/15) respectively. Complications include two cases of hematoma, one case of persistent pain and two cases of dehiscence. CONCLUSION: Constricted posterior fourchette seriously affects the quality of life. Y-V-plasty and 5-Z-Flap-plasty can be utilized to treat the two subtypes of constricted posterior fourchette, which can effectively reduce the pain score of patients with high satisfaction and few long-term complications.