⁶⁸Ga-NOTA-Aca-BBN(7-14) PET imaging of GRPR in children with optic pathway glioma.

Abstract

Optic pathway glioma (OPG) is a rare neoplasm that arises predominantly during childhood. Its location in a sensitive region involving the optic pathways, onset in young patients and controversial therapy choice make the management of OPG a challenge in paediatric neuro-oncology. In this study we assessed gastrin-releasing peptide receptor (GRPR)-targeted positron emission tomography (PET) imaging in children with OPG, and the application of a PET/MRI imaging-guided surgery navigation platform. Eight children (five boys, mean age 8.81 years, range 5-14 years) with suspicion of optic pathway glioma on MRI were recruited. Written informed consent was obtained from all patients and legal guardians. Brain PET/CT or PET/MRI acquisitions were performed 30 min after intravenous injection of 1.85 MBq/kg body weight of ⁶⁸Ga-NOTA-Aca-BBN(7-14). Four patients also underwent ¹⁸F-FDG brain PET/CT for comparison. All patients underwent surgical resection within 1 week. All 11 lesions (100%) in the eight patients showed prominent ⁶⁸Ga-NOTA-Aca-BBN(7-14) uptake with excellent contrast in relation to surrounding normal brain tissue. Tumour-to-background ratios (SUVmax and SUVmean) were significantly higher for ⁶⁸Ga-NOTA-Aca-BBN(7-14) than for ¹⁸F-FDG (28.4 ± 5.59 vs. 0.47 ± 0.11 and 18.3 ± 4.99 vs. 0.35 ± 0.07, respectively). Fusion images for tumour delineation were obtained in all patients using the PET/MRI navigation platform. All lesions were pathologically confirmed as OPGs with positive GRPR expression, and 75% were pilocytic astrocytoma WHO grade I and 25% were diffuse astrocytoma WHO grade II. There was a positive correlation between the SUV of ⁶⁸Ga-NOTA-Aca-BBN(7-14) and the expression level of GRPR (r² = 0.56, P < 0.01, for SUVmax; r² = 0.47, P < 0.05, for SUVmean). This prospective study showed the feasibility of ⁶⁸Ga-NOTA-Aca-BBN(7-14) PET in children with OPG for tumour detection and localization. ⁶⁸Ga-NOTA-Aca-BBN(7-14) PET/MRI may be helpful for assisting surgery planning in OPG patients with severe symptoms, GRPR-targeted PET has the potential to provide imaging guidance for further GRPR-targeted therapy in patients with OPG.