Quantitative susceptibility-weighted imaging in predicting disease activity in multiple sclerosis

Purpose Repeated use of Gadolinium (Gd) contrast for multiple sclerosis (MS) imaging leads to Gd deposition in brain. We aimed to study the utility of phase values by susceptibility weighted imaging (SWI) to assess the iron content in MS lesions to differentiate active and inactive lesions. Methods MS persons who underwent MRI were grouped into group 1 with active lesions and group 2 with inactive lesions based on the presence or absence of contrast enhancing lesions. Phase values of lesions ( P L ) and contralateral normal white matter ( P N ) were calculated using the SPIN software by drawing ROI. Subtracted phase values ( P S = P L − P N ) and iron content ( P S /3) of the lesions were calculated in both groups. Results We analyzed 69 enhancing lesions from 22 patients (group 1) and 84 non-enhancing lesions from 29 patients (group 2). Mean-subtracted phase values and iron content corrected for voxels in ROI were significantly lower in enhancing lesions compared to non-enhancing lesions ( p < 0.001). A cut-off value 2.8 μg/g for iron content showed area under the curve of 0.909 with good sensitivity. Conclusion Quantification of iron content using SWI phase values holds promise as a biomarker to differentiate active from inactive lesions of MS.