Comparison of 68 Ga-DOTANOC PET/CT with anatomical imaging in opsoclonus-myoclonus-ataxia syndrome in children: A retrospective analysis

Introduction: Opsoclonus-myoclonus-ataxia syndrome (OMAS), also known as “Kinsbourne syndrome” or “dancing eye syndrome,” is a rare immune-mediated paraneoplastic neurological syndrome that may be associated with pediatric neuroblastoma in approximately 2-3% of children aged 1-3 years. OMAS carries a grave prognosis and is characterised by involuntary eye movements, muscle jerks, ataxia and behavioural changes. Paediatric neuroblastoma may be the only cause of OMAS in up to 50% of children. Routine tests to detect occult neuroblastoma include anatomical imaging of the chest and abdomen with USG/ CT/ MRI. 131 I-MIBG scintigraphy has also been used; however, its application is limited by its availability, need for strenuous patient preparation, and high radiation exposure. In this retrospective analysis, we evaluated children presenting with OMAS who underwent 68 Ga-DOTANOC PET/CT as a single screening study to detect neuroblastoma and stage the disease, in comparison to traditional anatomical imaging. Methods: Retrospective data from 68 Ga-DOTANOC PET/CT scans of 43 pediatric patients presenting with OMAS from January 2019 to June 2024 were evaluated. A somatostatin receptor (SSTR) expressing lesion with corresponding morphological change on the CT image was considered PET-positive, while no abnormal SSTR expression or lesion was considered PET-negative. The results of 68 Ga-DOTANOC PET/CT were also compared with prior anatomical imaging studies, which were available for 32 patients (in both PET-positive and PET-negative groups). Results: Of 43 patients (21 male, 22 female; mean age 1.5 years), 31 (72.1%) were PET-positive and 12 (27.9%) were PET-negative. The mean SUVmax of PET-positive lesions was 12.1 (SD = 6.6). Prior anatomical imaging studies (USG (n=13)/ CT (n=6)/ MRI (n=13)) were available in 32 patients and compared with 68 Ga-DOTANOC PET/CT. Discordance was seen in 5 patients with prior USG and 1 patient with prior MRI, in which lesions were missed in 3 patients on USG and 1 patient on MRI. One suspicious lesion was excluded from diagnosis by 68 Ga-DOTANOC PET/CT in 1 patient. According to the International Neuroblastoma Staging System (INSS), 24 (80%) were stage 1, 4 (6.4%) were stage 2, 1 (4%) were stage 3, and 2 (6.4%) were stage 4. Repeat 68 Ga-DOTANOC PET/CT was done in 7/31 of stage 1 patients after surgical excision, and all were PET-negative. Conclusion: In this retrospective analysis, we found that approximately 72% of children presenting with OMAS have neuroblastoma as the primary etiology. 68 Ga-DOTANOC PET/CT demonstrated high diagnostic performance, accurately identifying neuroblastoma and providing rapid diagnosis, detection of metastasis, and guidance for optimal management.