Calcification in Globus Pallidus and Putamen of Multiple Sclerosis Patients Versus Healthy Subjects Using Quantitative Susceptibility Mapping

BACKGROUND: Calcification has been well reported in basal ganglia and it grows rapidly in globus pallidus (GP) followed by putamen (PUT) and caudate nucleus because of their high metabolic rate and displays high susceptibility effects. Therefore, the current study focused on magnetic susceptibility effect of calcium content in normal and diseased tissue due to metabolic changes. OBJECTIVES: To evaluate calcium content in GP and PUT structures of multiple sclerosis (MS) patients versus healthy subjects using quantitative susceptibility mapping. PATIENTS AND METHODS: We compared 10 MS patients with mean age of 48.3 years (standard deviation [SD]=11.89) with 10 healthy subjects with mean age of 39.6 years (SD=11.52). Scanning of subjects was performed with high resolution (0.5×0.5×2 mm(3)) using susceptibility weighted imaging sequence on 3 Tesla (Trio-Siemens, Erlangen, Germany). Data was processed in homemade SPIN software to produce susceptibility mapping. Threshold was set in healthy subjects to detect calcium content in PUT and GP structures. RESULTS: Magnetic susceptibility(x) of calcium content was assessed by number of pixels induced by GP and PUT in MS patients as well as healthy subjects. Two sample t-test was used to assess the difference between susceptibilities of GP and PUT of MS patients (P = 0.06, P > 0.05). Susceptibilities of GP and PUT also showed P = 0.3 in healthy subjects. One way analysis of variance was used to assess the difference of susceptibilities in four variables of both populations. Insignificant results (P = 0.7, P > 0.05) were found among four variables. There was no statistically significant difference between magnetic susceptibilities of both populations. CONCLUSION: Statistical analysis of susceptibilities of MS patients versus healthy subjects found no excess deposition of calcium content in deep gray matter of MS patients. Calcification may not be considered as a biomarker of prognosis in MS.