Susceptibility-weighted image features in AQP4-negative-NMOSD versus MS

Objective To characterize the susceptibility-weighted image (SWI) features including paramagnetic rim and nodular lesions with signal intensity changes and central vein sign (CVS) associated with aquaporin 4 (AQP4)-immunoglobulin G (IgG)-negative neuromyelitis optica spectrum disorder (NMOSD), and explore whether they can be used as potential imaging biomarkers for differentiating multiple sclerosis (MS) from this disorder. Methods We prospectively recruited NMOSD with AQP4-IgG-negative (AQP4- NMOSD) and IgG-positive (AQP4+ NMOSD), and MS subjects from the Clinical and Imaging Patterns of Neuroinflammation Diseases in China (CLUE) project (NCT0410683) between 2019 and 2021. The SWI features including paramagnetic rim and nodular lesions with signal intensity changes and CVS were analyzed and compared among groups, and the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined for distinguishing MS from AQP4- NMOSD. Results We enrolled a total of 160 consecutive patients (22 AQP4- NMOSD, 65 AQP4+ NMOSD, and 73 MS). We observed paramagnetic rim lesion (0/120 lesions, 0%) and nodular (1/120, 1%) lesions with hypointense signals on SWI in the AQP4- NMOSD group. These characteristics were similar to those recorded from AQP4+ NMOSD patients (rim: 0/369 lesions, 0%, P=1.000; nodular: 10/369 lesions, 2.7%, P=1.000), but differed significantly from those observed in the MS group (rim: 162/1665 lesions, 9.7%, P<0.001; nodular: 392/1665 lesions, 23.5%, P<0.001). AQP4- NMOSD patients had fewer average CVS+ rate (12%) than MS patients (46%, p<0.001), similar to AQP4+ NMOSD (13%, p=1.000). The SWI imaging features denoting lesions with paramagnetic rim or nodular hypointense SWI signals showed 90.4% sensitivity, 95.5% specificity, 98.5% PPV, and 75% NPV, and the criteria with≥3 CVS lesions showed sensitivity of 91.8%, specificity of 90.9%%, PPV of 97.1%, and NPV of 76.9% in distinguishing MS from AQP4- NMOSD. Discussion The SWI imaging features including lesions with paramagnetic rim or nodular hypointense SWI signals and 3 CVS lesions carries useful information in distinguishing MS from AQP4- NMOSD.