Análise do osso mandibular através de atributos de imagem em radiografias panorâmicas: revisão sistemática sobre dimensão fractal e estudos observacionais com endocrinopatias relacionadas às paratireóides

Abstract

Bone mineral alterations may be related to changes in the parathyroid glands. In skeletal architecture and bone metabolism, the parathyroid glands regulate calcium, phosphate, and parathyroid hormone (PTH). These fundamental concepts provide an essential understanding of the metabolic basis of bone alterations. Both primary hyperparathyroidism (HPTP) and hypoparathyroidism (hypoPT) can cause skeletal changes due to alterations in PTH levels. Given that these changes are a condition related to osteometabolic alterations, conducting studies related to radiographic aspects in such individuals is justified. Thus, the present thesis consists of three chapters whose objectives respectively consist of: 1) Conducting a systematic review and meta-analysis regarding the precision test in osteoporosis diagnosis through calculations of fractal dimension in panoramic radiographs; 2) conducting an observational, case-control study on bone texture analysis through radiomic characteristics of mandibular trabecular bone; 3) conducting an observational, case-control study on bone morphological aspects using radiomorphometric indices in panoramic radiographs. In Chapter 1, a systematic review with meta-analysis was conducted to summarize the evidence on the feasibility of using fractal dimension (FD) in maxillomandibular imaging exams for screening patients with osteoporosis. High sensitivity search strategies were used, and items from QUADAS-2 and GRADE were assessed. Out of 1034 records, four studies were included. The meta-analysis showed that the overall sensitivity and specificity of DFFD were 86.17% and 72.68%, respectively. The studies showed low risk of bias. In Chapter 2, an observational, case-control study was conducted with groups diagnosed with HPTP, hypoPT, and control. First-order, second-order, and higher-order radiomic variables were used. The images were segmented into regions of interest (ROIs) (50x50 pixels). HPTP and hypoPT presented different radiomic characteristics compared to the control group in all ROIs (p < 0.05). Significant differences were observed in the mandibular condyle regions (R1), mandibular ramus (R2), mandibular molars (R3), region below the mandibular foramen (R4), in the values of fractal dimension, lacunarity, homogeneity, correlation, energy, and contrast. In Chapter 3, an observational, case-control study was conducted with patients diagnosed with HPTP and hypoPT. Cortical thickness was evaluated in quantitative and qualitative radiomorphometric indices. Patients underwent bone mineral density evaluation through DXA. The results showed statistically significant data for the three groups in BMI (p=0.008), (p=0.006). Patients with HPTP showed lower values for radiomorphometric indices IG, IA, and IM (p < 0.001). Prediction for low BMD among post-surgical hypoPT individuals exhibited an IM value (p=0.024). In HPTP, IG, IA, and IM indices were statistically significant predictors of low BMD (p < 0.05). The studies concluded: 1) This systematic review demonstrated that FD presented sensitivity and specificity values above 70%; in Chapter 2, medullary bone demonstrated distinct radiomic characteristics for low BMD in HPTP; in Chapter 3, cortical bone exhibited a significant reduction in mandibular indices in HPTP compared to hypoPT and control groups; 3) medullary bone demonstrated distinct radiomic characteristics for low BMD in HPTP.