Diagnosis and differential diagnosis of tertiary androgenetic alopecia with severe alopecia areata based on high‐resolution MRI.

Background and aim: No previous study investigated the anatomical changes of the scalp and hair follicles between tertiary androgenetic alopecia and severe alopecia areata using high‐resolution magnetic resonance imaging (HR‐MRI). This study aimed to explore the value of HR‐MRI in assessing alopecia. Materials and methods: Forty‐eight people were included in this study. The imaging indicators of the vertex and occipital scalp were recorded and compared. The logistic regression model was developed for the indicators that differed between tertiary androgenetic alopecia and severe alopecia areata. The receiver‐operating characteristic (ROC) curve was used to assess the diagnostic efficacy of the model for tertiary androgenetic alopecia and severe alopecia areata. Results: At the vertex, the thickness of the subcutaneous tissue layer, follicle depth, relative follicle depth, total number of follicles within a 2‐cm distance, and number of strands reaching the middle and upper third of the subcutaneous fat layer within a 2‐cm distance were statistically different between patients with tertiary androgenetic alopecia, those with severe alopecia areata, and healthy volunteers (p < 0.05). The logistic regression model suggested that the subcutaneous tissue layer thickness was important in discriminating tertiary androgenetic alopecia from severe alopecia areata. The ROC curve showed that the area under the curve, sensitivity, specificity, and best cutoff values of the subcutaneous tissue layer were 0.886, 94.4%, 70%, and 4.31 mm, respectively. Conclusions: HR‐MRI can observe the changes in anatomical structures of the scalp and hair follicles in patients with alopecia. HR‐MRI can be applied to the differential diagnosis of tertiary androgenetic alopecia and severe alopecia areata. [ABSTRACT FROM AUTHOR]