Ultrasonographic evaluation of submandibular salivary glands in female patients with hypothyroidism: a fractal analysis study.

BACKGROUND

Hypothyroidism is known to affect salivary gland physiology, yet structural alterations detectable by ultrasonography remain unclear. Fractal analysis (FA), a quantitative method for assessing tissue complexity, may aid in identifying subtle parenchymal changes. This study aimed to evaluate submandibular gland ultrasonographic texture in female hypothyroid patients using FA.

METHODS

Fifty female patients with medically controlled hypothyroidism and 50 age-matched healthy women were included in this cross-sectional study. The diagnosis of hypothyroidism was confirmed based on serum thyroid-stimulating hormone (TSH) levels. Standardized bilateral ultrasonographic imaging of the submandibular glands was performed using a high-frequency linear transducer under consistent acquisition parameters. Fractal dimension (FD) and grayscale histogram values were calculated from predefined 20 × 20 pixel regions of interest (ROIs) selected from homogeneous glandular parenchyma, excluding ducts and vascular structures. Image processing was performed using ImageJ software and included grayscale conversion, binarization, and skeletonization, followed by FD calculation using the box-counting method. Data normality was assessed using the Shapiro-Wilk test. Group comparisons were performed using the independent samples t-test or Mann-Whitney U test, as appropriate. Correlations were analyzed using Pearson or Spearman coefficients. A p-value < 0.05 was considered statistically significant.

RESULTS

No significant differences in FD or histogram metrics were observed between hypothyroid and control groups (p > 0.05). Within group comparisons showed no right left gland differences in the hypothyroid group. In controls, right side FD values were slightly but significantly lower than left side values (p = 0.020). Age and levothyroxine dose showed weak negative correlations with selected histogram measures.

CONCLUSIONS

FA of ultrasonographic images did not demonstrate detectable parenchymal alterations in the submandibular glands of medically controlled hypothyroid female patients. FA appears feasible but may be insufficient to identify subtle or treatment modulated changes. Combined morphological and functional assessments are recommended for future studies.