Morpometric evaluation of the brainstem using magnetic resonance imaging in parkinson patients

Objective: The aim of this study was to evaluate the brain stem morphometrically in Parkinson's disease using magnetic resonance imaging. Materials and Methods: This study included 100 patients over 50 years of age who applied to Dicle University Medical Faculty Hospital between January 2018 and January 2021 and were diagnosed with Parkinson's disease (PD) clinically and had a history of regular drug use (Group 2= Patient). These patients were compared with 100 patients who were clinically not diagnosed with Parkinson's disease (Group 1= Healthy). The sociodemographic characteristics of the patients (age, gender), anteroposterior diameter-area of the mesencephalon, anteroposterior diameter-area of the pons, ratio of the area of the mesencephalon to the pons, thickness of the substantia nigra, width of the cerebral crus and interpeduncular distance measurements were retrospectively evaluated. Results: A total of 200 individuals, including 100 patients and 100 healthy individuals, were included in our study (57.5% of them, n=115, were male). The average age in our study was found to be 64.1±9.6. The average anteroposterior diameter of the mesencephalon in individuals in Group 1 was 0.99±0.09 cm, and the average in individuals in Group 2 was 1.05±0.16 cm. A higher anteroposterior diameter of the mesencephalon was found in the patient group (group 2) and this difference was statistically significant (p=0.001). The average anteroposterior diameter of the pons in individuals in Group 1 was 2.11±0.13 cm, and the average in individuals in Group 2 was 2.17±0.17 cm. A higher anteroposterior diameter of the pons was found in the patient group (group 2) (p=0.003). The average area of the mesencephalon in Group 1 was 1.72±0.27 cm2, while in Group 2 it was 1.65±0.29 cm2 (p=0.058). The average area of the pons in individuals in Group 1 was 3.57±0.44 cm2, while in individuals in Group 2 it was 3.91±0.52 cm2 (p<0.001). The ratio of the mesencephalon/pons area in individuals in Group 1 was 0.48±0.07, while in individuals in Group 2 it was 0.42±0.09 (p<0.001). The interpeduncular distance in individuals in Group 1 was 0.66±0.05 cm, while in individuals in Group 2 it was 0.73±0.12 cm (p<0.001). The thickness of the substantia nigra in individuals in Group 1 was 2.98±0.33 cm, while in individuals in Group 2 it was 2.66±0.4 cm (p<0.001). The width of the right cerebral crus in individuals in Group 1 was 1.53±0.13 cm, while in individuals in Group 2 it was 1.57±0.14 cm (p=0.047). The width of the left cerebral crus in individuals in Group 1 was 1.54±0.11 cm, while in individuals in Group 2 it was 1.61±0.32 cm (p=0.047). The width of the right cerebellar peduncle in individuals in Group 1 was 1.62±0.13 cm, while in individuals in Group 2 it was 1.68±0.14 cm (p=0.001). The width of the left cerebral peduncle in individuals in Group 1 was 1.63±0.13 cm, while in individuals in Group 2 it was 1.69±0.13 cm (p=0.002). When only the patient group was considered, a significant negative correlation (r=-0.284) was found between age and pons area. Similarly, a significant negative correlation (r=-0.281**) was found between age and the width of the right cerebellar peduncle. Particularly, it was found that the measurement of interpeduncular distance provided the highest Area Under the Curve (AUC) value of 0.716 with a sensitivity of 49% and a specificity of 91%. This could be an effective indicator in the diagnosis of a particular disease when the cut-off value is set at 0.74. Also, the measurement of the pons area emerged as a significant finding. It was found that the area of the pons provided an AUC value of 0.692 with a sensitivity of 77% and a specificity of 54%. This could help identify the disease with a cut-off value of 3.59. We also did a reverse ROC analysis for values that negatively correlate with the presence of the disease. The measurement of substantia nigra thickness provided the highest AUC value of 0.744 with a sensitivity of 25% and a specificity of 90%. This could be an effective indicator in the diagnosis of Parkinson's disease when the cut-off value is set at 3.20. Also, the measurement of the mesencephalon/pons area ratio emerged as a significant finding. This measurement provided an AUC value of 0.702 with a sensitivity of 45% and a specificity of 81%. This could help identify the disease with a cut-off value of 0.49. On the other hand, the AUC value of the measurement of the mesencephalon area was found to be lower (with a sensitivity of 64% and a specificity of 46% with 0.582). Conclusion: These findings suggest that measurements of certain anatomical features may be important in the diagnosis of Parkinson's disease and perhaps in the detection of its early stages. This requires further investigation of these features and the development of diagnostic tools based on these features. However, these results also reveal the need for this research to be repeated on a larger scale and with different demographic groups.