Aquaporin-4 Immunoglobulin G-seropositive Neuromyelitis Optica Spectrum Disorder MRI Characteristics: Data Analysis from the International Real-World PAMRINO Study Cohort

Background: Patients with neuromyelitis optica spectrum disorder (NMOSD) are often seropositive for antibodies against aquaporin-4 (AQP4). The importance of MRI monitoring in this disease requires evaluation. Purpose: To profile MRI features from a large international cohort with AQP4 immunoglobulin G (IgG)-seropositive NMOSD (from the Parallel MRI in NMOSD [PAMRINO] study) and to evaluate and confirm existing knowledge regarding the incidence, location, and longitudinal development of characteristic lesions in the central nervous system associated with AQP4-IgG-seropositive NMOSD. Materials and Methods: In this retrospective study (from August 2016 to January 2019), MRI and clinical data were collected from 17 NMOSD expert sites in 11 countries across four continents. Clinical features and lesions identified at cross-sectional and longitudinal MRI were assessed. No formal statistical tests were used to compare observations; however, means, SDs, and 95% CIs are reported when evaluating lesion frequencies. Results: Available T1-weighted and T2-weighted MRI scans in patients with AQP4-IgG-seropositive NMOSD (n = 525) were read. Among the 525 patients, 320 underwent cerebral MRI examinations with T2-weighted hyperintense cerebral (264 of 320; 82.5%), cerebellar (44 of 320; 13.8%), and brainstem (158 of 321 [49.2%], including one lesion observed at cervical spinal cord [SC] MRI) lesions. Lesions in the optic nerves, analyzed from 152 MRI examinations, were mainly found in the central (81 of 92; 88%) and posterior (79 of 92; 86%) sections (bilaterally in 39 of 92; 42%). Longitudinally extensive transverse myelitis was the predominant SC lesion pattern (upper compartment from 322 MRI examinations, 133 of 210 [63.3%]; and lower compartment from 301 MRI examinations, 149 of 212 [70.3%]). However, nonlongitudinal extensive transverse myelitis lesions were also observed frequently (105 of 210; 50.0%) in the cervical SC. Clinical data (n = 349; mean age, 44 years ± 14 [SD]; 202 female patients) and acute lesions at contrast-enhanced (CE) MRI (n = 58, performed within 30 days of the last attack) were evaluated. CE lesions were detected in the cerebrum (eight of 13; 62%), optic nerves (14 of 19; 74%), or chiasm (three of four; 75%) within 15 days of any relapse. In the upper SC (29 of 44; 66%), CE lesions were frequently observed up to 20 days after a clinical myelitis event. Conclusion: A high incidence of abnormal brain MRI examinations and nonlongitudinal extensive SC lesions was found in patients in PAMRINO with AQP4-IgG-seropositive NMOSD.