Utilization of Ga-68 Dotatate PET/CT in Differentiating Brain Radiation Necrosis from Tumor Progression in a Case of Metastatic Olfactory Neuroblastoma
Objective:
To report a case of metastatic olfactory neuroblastoma in which Ga-68 Dotatate Positron emission tomography(PET) scan was helpful in differentiating between brain radiation necrosis and progression of the disease.
Background:
Somatostatin receptor 2(SSTR2) expression is commonly observed in olfactory neuroblastoma, with reported rates of 75-99% in cases. While fluorodeoxyglucose(FDG) PET or Brain perfusion magnetic resonance imaging(MRI) is used to differentiate between radiation necrosis and tumor progression, their sensitivity and specificity are not high. Ga-68 Dotatate PET has shown excellent sensitivity and septicity and has used in evaluating tumors expressing SSTR2, including olfactory neuroblastomas and other neuroendocrine tumors, for purposes of diagnosis, staging, treatment planning, and monitoring disease status post-treatment.
Design/Methods:
We present the case of a 62-year-old man initially diagnosed with Kadish stage C, Hyams grade 3 olfactory neuroblastoma in 2016. The patient underwent surgery, chemotherapy and radiation therapy but had multiple recurrences and developed metastatic lesions, requiring multiple surgeries and re-radiations. Subsequently he developed pathology-proven radiation necrosis in the frontal lobes adjacent to the region original tumor was located. Follow-up brain MRI showed continuous growth of right orbit mass and further worsening of enhancing right frontal lobe lesion where he had both radiation necrosis and original tumor. Ga-68 Dotatate PET was performed which demonstrated FDG-avid orbital mass lesion but no FDG activity in the enhancing right frontal lesion. The distinction was essential for differentiating the nature of the right frontal lobe lesion and for surgical planning.
Conclusions:
To the author's knowledge, this case represents the first example where Ga-68 Dotatate PET was instrumental in differentiating between radiation necrosis and disease progression in a patient with olfactory neuroblastoma. This case exemplifies the potential usefulness of Dotatate PET in distinguishing tumor growth or recurrence from other etiologies such as radiation necrosis, thereby enhancing clinical decision-making in the management of olfactory neuroblastoma.
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