Comparative study of Susceptibility Map Weighted Image (SMWI) with Susceptibility Weighted Image (SWI) in substantia nigra for the diagnosis of Idiopathic Parkinson’s Disease and correlation with 18F-FP-CIT-PET
Purpose: Susceptibility Weighted Image (SWI) and Susceptibility Map Weighted Image (SMWI) are well known for delineating iron pathology of substantia nigra. The purpose of this study is to compare the image quality and diagnostic performance of SMWI and SWI in diagnosis of idiopathic Parkinson Disease (IPD) with 18F-FP-CIT PET as reference standard.
Materials and methods: Patients who were clinically suspected for IPD were included in this retrospective study and their 3T brain MRI including SWI and 18F-FP-CIT PET results were obtained. Visual assessment of nigral hypersensitivity in SWMI and SWI were performed and their correlation with 18F-FP-CIT PET were compared using sensitivity, specificity, and diagnostic accuracy. Additional contrast-to-noise ratio of nigrosome-1 (CNRN1) were calculated in the control group including ET, DIP and VP patients for quantitative assessment. Correlation of SMWI and SWI with 18F-FP-CIT PET and diagnostic performance were compared using ROC curve.
Results: Total of 122 patients were included in this study. SWMI showed higher sensitivity (Rt : 76.1% vs 70.7%, Lt : 69.0% vs 58.6%) and specificity (Rt : 66.7% vs 63.3 %, Lt : 68.6% vs 62.9%) than SWI for nigral hyperintensity in both sides as compared to 18F-FP-CIT PET. CNRN1 of SMWI was significantly higher than that of SWI (1.91±0.43 vs 1.50±0.52). Overall diagnostic accuracy of SMWI was significantly higher than that of SWI (80.3% vs 76.2%, p<0.05). Interobserver agreements for nigral hyperintensity in SWI were fair and good for both sides of nigrosome (Rt : κ=0.721, Lt : κ=0.724), where as those of SMWI were excellent for both sides (Rt : κ=0.932, Lt : κ=0.928).
Conclusion: SMWI showed better image quality and higher diagnostic performance than SWI in diagnosis of IPD at 3T MRI with 18F-FP-CIT PET as reference standard.
