Imaging features to distinguish AQP4-positive NMOSD and MS at disease onset: A retrospective analysis in a single-center cohort.

PURPOSE: To compare the diagnostic performance of imaging criteria that differentiate AQP4+ Neuromyelitis Optica Spectrum Disorders (NMOSD) and Multiple Sclerosis (MS) at disease onset (DO) and follow-up (FU). METHODS: We retrospectively analyzed MRI scans at DO (defined as the first 60 days of patient-reported symptom onset) in 10 AQP4+NMOSD and 25 (time to MRI matched) relapsing-remitting MS patients from a monocentric cohort. RESULTS: The Matthews criteria were met in 20% of AQP4+NMOSD patients at DO vs. 33% at FU, and in 96% of RRMS patients vs.100% at FU. Specificity (SP) and sensitivity (SE) were thus high at both time-points: SP-DO: 96%; SP-FU:100%; and SE-DO: 80%; SE-FU: 67%, with similar area under the curve (AUC) values at DO: 88% [95% CI 74%-100%] and FU: 83% [95% CI 67%-100%]. The Cacciaguerra criteria were met in 90% of AQP4+NMOSD patients at DO vs. 88.9% at FU and in 24% of RRMS patients vs. 14% at FU; SP-DO: 87%; SP-FU: 86%; and SE-DO: 90%; SE-FU: 89%, with similar AUC values at DO: 88% [95% CI 76%-98%] and FU: 87% [95% CI 74%-98%]. CONCLUSIONS: While diagnostic MRI criteria were developed on data acquired years after disease onset, our study demonstrates their high applicability at the earliest disease stages, thus emphasising their valuable use in clinical practice.