Somatostatin receptor positron emission tomography/computed tomography (PET/CT) in the evaluation of opsoclonus-myoclonus ataxia syndrome
A two and half year old male child presented with acute onset of myoclonus, occasional opsoclonus and ataxia. Previous evaluation included a lumbar puncture and brain MRI, both failing to show an abnormality. Suspicion of paravertebral mass was raised in a recent chest X-ray. Considering the possibility of the mass being neuroblastoma, the patient was referred to the nuclear medicine department for further evaluation. We evaluated the child with SSR PET/CT using 68Gallium DOTATATE. 1.5 mCi of 68Gallium-DOTATATE was injected intravenously to the patient. After 1 hr of injection, patient was scanned on dedicated 16 slice PET /CT (GE – STE 16). Whole body diagnostic CT scan was obtained as part of PET/CT protocol on Multislice CT with 3.5 mm slice thickness.\nThe SSR PET/CT revealed intense tracer uptake in chest which localized to a soft tissue density mass in the paravertebral region (T1-T4 levels) with SUVmax of 21.0 [, long arrow]. On CT the lesion showed evidence of calcification in it [, arrow]. Considering patient's symptoms, these CT findings along with positivity for somatostatin receptor expression on PET, suggested diagnosis of NB. Additionally multiple areas of increased tracer uptake were noted in the bone marrow of long bones and almost entire axial skeleton with no obvious CT demonstrable abnormality [Figure and ]. These features were indicative of widespread marrow metastases. Biopsy of the paravertebral mass confirmed the diagnosis of NB. Considering the extensive disease, the child is receiving chemotherapy for last four months. There is mild clinical improvement in the OMA.