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

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