Assessment of the amount of basal ganglia iron deposition in patient with Parkinson's disease using quantitative susceptibility mapping (QSM)

Abstract

Studies have demonstrated that increased brain iron concentration is associated with Parkinson’s disease. Parkinson’s is the most common degenerative neurological disorder after Alzheimer’s disease. Many studies have shown some imaging techniques can measure the amount of iron deposition in the brain as a biomarker for Parkinson’s prognosis. Research have shown that Quantitative Susceptibility Mapping (a technique based on echo gradient imaging) has more sensitivity than T2-weighted imaging, T2* and R2* mapping. A few studies have been done to evaluate the amount of iron in the nuclei of the basal ganglia of brain (Red Nucleus, Sub stantia Nigra, Caudate, Globus, Putamen, Thalamic) in Parkinson’s disease. Therefore, it seems necessary to investigation of this method and assessment the relationship between stage of disease, age, gender and diagnostic value of this method. Therefore, our goal in this study was to measure the concentration of iron deposition in the basal ganglia by two methods of QSM and measurement iron content and comparing the diagnostic value of these methods in every nucleus, separately. Methods: Number of 30 patients with Parkinson’s disease were examined by a neurologist and were categorized at three different stages. Hoehhn and Yahr tests was used for the staging of patient. Number of 15 healthy individuals were considered as control group. The routine brain sequences and the QSM special sequence were performed by the SIEMENS MAGNETOM TRIO 3T system. The SPIN software was used to processing and analyzing the images. The images were processed using three filters: BET, SHARP, Inverse Filter, and a high pass filter. Then using QSM images were overlaid on the MP-RAGE sequence images. Finally, the susceptibility of each nucleus was measured separately with the available tool. To analyzing, we used SPSS version 18 and regression, correlation coefficient and ROC curve. Results: The sixteen percent of subjects were male and 40% were female. The mean age of patient and control group was 66.2 and 63.7 years, respectively. There were 8, 11 and 11 patients in stage 1, 2 and 3, respectively. There was a significant difference between control and patient groups in magnetic susceptibility mapping (QSM) of sub stantia, red nucleus, and globus pallidus nuclei. The highest iron deposition was found in red cores, globus pallidus and substantia nigra, but there was no significant difference between the control group and the patient. The association between age with QSM was significant in the nucleus of globus pallidus (r = 0.305, P = 0.042). The relationship between the stage of the disease with QSM was significant in globus pallidus, red and substantia nigra nuclei. The correlation between age and iron content just in the globus pallidus nucleus was statistically significant. The relationship between the stage of the disease and the iron deposition in the nucleus of globus pallidus and substantia nigra was significant. Iron deposition with QSM has correlation in substantia nigra, red nucleus, putamen, globus pallidus, thalami and Caudate nuclei. We also obtained the Sensitivity, Specificity, and accuracy for both QSM and iron content for all six nuclei, separately. Conclusion: The QSM is a good choice for the detection of pathologic changes in patients with PD. QSM can identify the patient signature of PD, and its discrimination between patients with PD and controls is highly accurate, Specially in substantia nigra, red nucleus globus pallidus. Also, QSM can be used to staging the PD. Our findings suggest that QSM may be valuable for the diagnosis and assessment of PD.