Uptake of 4-borono-2-[18F]fluoro-L-phenylalanine in sporadic and neurofibromatosis 2-related schwannoma and meningioma studied with PET.
OBJECTIVE
Meningiomas and schwannomas associated with neurofibromatosis 2 (NF2) are difficult to control by microsurgery and stereotactic radiotherapy alone. Boron neutron capture therapy (BNCT) is a chemically targeted form of radiotherapy requiring increased concentration of boron-10 in tumour tissue. PET with the boron carrier 4-borono-2-[(18)F]fluoro-L-phenylalanine ([(18)F]FBPA) allows investigation of whether 4-borono-L-phenylalanine (BPA) concentrates in NF2 tumours, which would make BNCT feasible.


METHODS
We studied dynamic uptake of [(18)F]FBPA in intracranial meningiomas (n=4) and schwannomas (n=6) of five sporadic and five NF2 patients. Tracer input function and cerebral blood volume were measured. [(18)F]FBPA uptake in tumour and brain was assessed with a three-compartmental model and graphical analysis. These, together with standardised uptake values (SUVs), were used to define tumour-to-brain [(18)F]FBPA tissue activity gradients.


RESULTS
Model fits with three parameters K (1) (transport), k (2) (reverse transport) and k (3) (intracellular metabolism) were found to best illustrate [(18)F]FBPA uptake kinetics. Maximum SUV was two- to fourfold higher in tumour as compared with normal brain and independent of NF2 status. The increased uptake was due to higher transport of [(18)F]FBPA in tumour. In multiple-time graphical analysis (MTGA, Gjedde-Patlak plot) the tumour-to-brain [(18)F]FBPA influx constant (K (i) -MTGA) ratios varied between 1.8 and 5.4 in NF2-associated tumours while in sporadic tumours the ratio was 1-1.4.


CONCLUSIONS
[(18)F]FBPA PET offers a viable means to evaluate BPA uptake in meningiomas and schwannomas in NF2. Based on our results on tumour uptake of [(18)F]FBPA, some of these benign neoplasms may be amenable to BNCT.
Havu-Aurén
Katja
K
Turku PET Centre, University of Turku, P.O. Box 52, 20521, Turku, Finland. katja.havu@tyks.fi
Kiiski
Johanna
J
Lehtiö
Kaisa
K
Eskola
Olli
O
Kulvik
Martti
M
Vuorinen
Ville
V
Oikonen
Vesa
V
Vähätalo
Jyrki
J
Jääskeläinen
Juha
J
Minn
Heikki
H
D000328:Adult; D001896:Boron Compounds / Q000493:pharmacokinetics* / Q000627:therapeutic use; D016754:Boron Neutron Capture Therapy / Q000379:methods; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism* / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism* / Q000532:radiotherapy; D008579:Meningioma / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism* / Q000532:radiotherapy; D008875:Middle Aged; D009442:Neurilemmoma / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism* / Q000532:radiotherapy; D017253:Neurofibromatoses / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000532:radiotherapy; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000627:therapeutic use
D001896:Boron Compounds; D019275:Radiopharmaceuticals; C072915:4-borono-2-fluorophenylalanine; D010649:Phenylalanine