Clinical utility of Ga68 DOTANOC PET/CT imaging in juvenile nasal angiofibroma and the PARIS protocol: a preliminary report.

OBJECTIVES: Juvenile nasopharyngeal angiofibroma (JNA) expresses different somatostatin cell surface receptors and Ga68 [DOTA, 1-Nal3]-octreotide (DOTANOC)-PET/computed tomography (CT) scan may be used for its imaging. Also, functional imaging with DOTANOC-PET/CT may promise of greater accuracy in the detection or exclusion of recurrent/residual JNA.

METHODS: In this prospective study, five JNA patients who underwent a DOTANOC-PET-CT scan both preoperatively and postoperatively during June 2018-March 2020 were included. Postcontrast enhancement of a definite lesion was considered residual/recurrent tumor in contrast-enhanced MRI (CEMRI). In DOTANOC-PET/CT, any abnormal uptake apart from physiological sites was considered as residual lesions. Radiological results were categorized as negative, suspicious or definite residual/recurrent tumors. Any discrepancy was resolved by endoscopic biopsies.

RESULTS: Preoperatively all five cases of JNA showed avid DOTANOC expression in the tumor. The mean (SD) value of DOTANOC standardised uptake value in the tumor was 4.3 (1.4) (range = 2.1-6.2). In postoperative CEMRI evaluation, three of five patients had residual tumors and two had normal scans. On DOTANOC-PET/CT, two of five patients had residual tumors and three had normal scans. In one patient with residual tumor, the discrepancy with regard to tumor extent was noted in two scans, and further biopsy confirmed the findings of DOTANOC-PET/CT as accurate.

CONCLUSION: 68Ga-DOTANOC-PET/CT uptake is universal in JNA and appears to be more specific in the identification of residual/recurrent JNA. In residual tumors, DOTANOC-PET/CT may have an advantage over CEMRI in the diagnosis, decision making and planning stereotactic radiation. However, these findings are to be validated in studies with larger patients.