Micro-CT-Based Bone Microarchitecture Analysis of the Murine Skull

Osteonecrosis of the Femoral Head in People Living With Human Immunodeficiency Virus: A Micro-Computed Tomography Study

Background

The incidence of osteonecrosis of the femoral head (ONFH) in people with human immunodeficiency virus (HIV) is 10-100 times higher than that in the general population. However, the specific bone microstructure and extent of damage within the femoral head in PWH are still unclear.

Methods

Femoral head samples were obtained by total hip arthroplasty, micro-computed tomography (micro-CT) was employed to investigate the microstructure of trabecular bone across 4 representative regions within necrotic femoral heads, and quantitative analysis was performed.

Results

On general observation, different degrees of degenerative cartilage, fibrocartilage, hyperplastic bone, and exposed bone were presented alternately, with a "map-like" appearance. On micro-CT, compared with the normal and necrotic areas, the bone volume/tissue volume and bone mineral density of the sclerotic areas were significantly increased, the number of trabeculae was significantly increased, and the gap was smaller (P < .05). There was no significant difference in trabecular thickness among the groups (P < .05).

Conclusions

The systemic immune syndrome caused by HIV itself may interfere with the normal metabolism of bone, including osteoblasts and osteoclasts, and thus participate in HIV-related ONFH.

Computed tomography assessment of hypodontia and crown size in hemifacial microsomia

OBJECTIVE

Our aims were to assess the prevalence of hypodontia in unilateral hemifacial microsomia (HFM), and to compare tooth (crown) size between affected and unaffected sides.

DESIGN

In a retrospective cross-sectional study of South Australians, computed tomography (CT) scans were used to assess hypodontia and crown size (mesiodistal length, buccolingual width and crown height). The inclusion criteria were the absence of other congenital anomalies and the availability of CT scans. The exclusion criteria were the lack of extraction history or reproducible landmarks for morphometric assessment. The final sample comprised 41 participants in both dentitions, including 32 children and 9 adults (median age 13.9 years, range 0.4 - 47.6 years; 19 males and 22 females). Hypodontia was assessed in all participants, and the permanent crown size in 30 (73.2%) participants. Linear mixed-effects models were performed to determine if crown size was significantly different between the two sides, controlling for sex, HFM severity, and tooth and jaw type.

RESULTS

Hypodontia occurred in none of the participants in the primary dentition, but in 6/30 (20%) participants in the permanent dentition (3/30 each on the affected and unaffected sides). There was no significant difference in the mean crown dimensions between the two sides, but the crown size was larger in males (p < 0.05), except for mesiodistal length, and became progressively smaller with increased HFM severity (p < 0.05).

CONCLUSIONS

Hypodontia spared the primary dentition but featured prominently in the permanent dentition. The permanent crown dimensions were unaltered between the two sides.

Application of medical imaging methods and artificial intelligence in tissue engineering and organ-on-a-chip

Organ-on-a-chip (OOC) is a new type of biochip technology. Various types of OOC systems have been developed rapidly in the past decade and found important applications in drug screening and precision medicine. However, due to the complexity in the structure of both the chip-body itself and the engineered-tissue inside, the imaging and analysis of OOC have still been a big challenge for biomedical researchers. Considering that medical imaging is moving towards higher spatial and temporal resolution and has more applications in tissue engineering, this paper aims to review medical imaging methods, including CT, micro-CT, MRI, small animal MRI, and OCT, and introduces the application of 3D printing in tissue engineering and OOC in which medical imaging plays an important role. The achievements of medical imaging assisted tissue engineering are reviewed, and the potential applications of medical imaging in organoids and OOC are discussed. Moreover, artificial intelligence - especially deep learning - has demonstrated its excellence in the analysis of medical imaging; we will also present the application of artificial intelligence in the image analysis of 3D tissues, especially for organoids developed in novel OOC systems.

Micro-computed tomography assessment of bone structure in aging mice

High-resolution computed tomography (CT) is widely used to assess bone structure under physiological and pathological conditions. Although the analytic protocols and parameters for micro-CT (μCT) analyses in mice are standardized for long bones, vertebrae, and the palms in aging mice, they have not yet been established for craniofacial bones. In this study, we conducted a morphometric assessment of craniofacial bones, in comparison with long bones, in aging mice. Although age-related changes were observed in the microarchitecture of the femur, tibia, vertebra, and basisphenoid bone, and were more pronounced in females than in males, the microarchitecture of both the interparietal bone and body of the mandible, which develop by intramembranous ossification, was less affected by age and sex. By contrast, the condyle of the mandible was more affected by aging in males compared to females. Taken together, our results indicate that mouse craniofacial bones are uniquely affected by age and sex.