Contribution of diffusion tensor imaging to conventional MRI for diagnosis in patients with multiple sclerosis

The aim of this study was to quantitatively demonstrate the diffusion abnormalities of white matter that appear as plaque, peri-plaque and as normal with diffusion tensor imaging in multiple sclerosis patients through FA and ADC measurements. Furthermore, it was aimed to investigate whether anisotropic diffusion, isotropic diffusion, is superior to and conventional magnetic resonance imaging for understanding the pathophysiology of MS disease by FA and ADC measurements for determining the active and chronic plaques. 54 patients (mean age: 38±12 years) followed-up with the diagnosis of multiple sclerosis and 56 healthy control group individuals (mean age 31±7 years) underwent brain MR and Diffusion Tensor Imaging (DTI) examinations. FA and ADC measurements were made from the plaque, the peri-plaque area, the white matter contralateral to the plaque that appeared normal (CP-NAWM) and normally appearing white matter (NAWM) areas in MS patients and from the normal white matter (NWM) in the control group individuals. Taking into consideration the contrast enhancement pattern of the plaques in MS patients, the contrast enhancing plaques were evaluated as active and the non-enhancing plaques were evaluated as chronic plaques. FA and ADC measurements were made from both active and chronic plaques. The measurements were made by an experienced radiologist and were compared within MS patients and with the control group statistically. When the degree of anisotropy was compared to the control group, the degree of plaques was found lowest. And it was observed to be increase in peri-plaque, CP-NAWM and NAWM, respectively. At the level of plaque and periplak ADC value was found to be higher than the control group.There was no significant difference between the ADC values of CP-NAWM and NAWM and the control group. It has been demonstrated that the difference between plaque (p<0.01), peri-plaque (p<0.01), CP-NAWM (p<0.01) and NAWM (p=0,047) FA values in MS patients and NWM FA values of the control group was significant. It has been demonstrated that the difference between the plaque (p<0.01) and peri-plaque (p<0.01) ADC values and the control group‟s ADC values was also statistically significant. However, the difference between CP-NAWM (p=0,688) and NAWM (p=0,719) ADC values and the control group‟s ADC values were determined not to be statistically significant. The active plaque FA value was found to be lower than the chronic plaque FA value, and the chronic plaque FA was found to be lower than the NWM FA value. However, the difference between the FA values of active plaque and chronic v plaque was not statistically significant (p=0,165). The chronic plaque ADC value was determined to be higher than that of the active plaque, and the active plaque ADC value was determined to be higher than the control group ADC value. The ADC value between the active plaque and the chronic plaque was not statistically significant (p=0,504). The progressive increase in the anisotropy from normally appearing white matter to peri-plaque white matter and plaque level demonstrates the myelin damage. In our study, we observed that the increase in anisotropy we observed to be lower in the peri-plaque area than plaque, but higher than the NAWM demonstrates that the white matter abnormalities extend towards the plaque and through this way, the white matter that appears normal in conventional MRI is actually not normal, and is affected by MS disease. Furthermore, it has been determined that anisotropic measurements evaluate the white matter abnormalities in MS patients more sensitively than ADC measurements. Based on these results, it has been suggested that DTI will be more beneficial than conventional MRI and diffusion MRI for evaluating the disease burden in MS patients.