Diffusion Tensor Imaging in Assessment of White Matter Micro-Structural Changes in Adult-Onset Idiopathic Focal Cervical Dystonia

Background: Diffusion tensor imaging (DTI) metrics include fractional anisotropy (FA) that allow estimating the directions of diffusion of water molecules so it can indicate the nerve fibers alignments and mean diffusivity (MD) that represents the overall magnitude of water diffusion and is mainly influenced by density of different cells as well as the extracellular space structure.
Objectives: To assess the added value of DTI using a ROI-based analysis as a quantitative evaluation of the white matter micro-structural changes among patients diagnosed with adult-onset idiopathic focal cervical dystonia.
Patients and methods: This prospective case-control study investigates the utility of diffusion tensor imaging (DTI) metrics fractional anisotropy (FA), mean diffusivity (MD), and apparent diffusion coefficient (ADC) in detecting microstructural white matter changes in adults with idiopathic focal cervical dystonia (AOIFCD). Forty-five patients with AOIFCD, their mean age was 40.51 ± 7.45 years, 14   of them were males (31.11%) and 31 were females (68.89%). Other twenty age and sex-matched healthy controls were enrolled in the study to compare their data with the diseased group, both groups underwent DTI on a 1.5T MRI scanner The study quantitatively compared DTI parameters across 17 brain regions, including both white and grey matter structures, and performed tractography of the corticospinal tracts (CST). Diagnostic performance was evaluated using ROC curve analysis.
Results: The diagnostic performance of the measured DTI parameters exhibited, as regard FA it demonstrated that the highest area under curve (AUC) was for FA at right putamen (0.995, p<0.001*), while as regard to the diagnostic performance of the measured MD, it demonstrated that the highest AUC was for MD at Cortico-Spinal Tract (CST) (1, p<0.001*), with sensitivity& specificity of 100 % both. Assessment of the diagnostic performance of the measured apparent diffusion coefficient (ADC) demonstrated that the highest AUC was for ADC at left cerebellar hemisphere, ADC at Corpus Callosum (CC) genu, ADC at CC splenium and ADC at CST (1, p<0.001*), with a sensitivity &specificity both of 100%.
Conclusion: The integration of quantitative DTI parameters across multiple white matter regions provides a robust framework for identifying microstructural changes in patients with adult-onset idiopathic focal cervical dystonia.