title: PET SUV correlates with radionuclide uptake in peptide receptor therapy in meningioma.
abstract: OBJECTIVE
  To investigate whether the tumour uptake of radionuclide in peptide receptor radionuclide therapy (PRRT) of meningioma can be predicted by a PET scan with (68)Ga-labelled somatostatin analogue.
  
  
  METHODS
  In this pilot trial, 11 meningioma patients with a PET scan indicating somatostatin receptor expression received PRRT with 7.4 GBq (177)Lu-DOTATOC or (177)Lu-DOTATATE, followed by external beam radiotherapy. A second PET scan was scheduled for 3 months after therapy. During PRRT, multiple whole-body scans and a SPECT/CT scan of the head and neck region were acquired and used to determine the kinetics and dose in the voxel with the highest radionuclide uptake within the tumour. Maximum voxel dose and retention of activity 1 h after administration in PRRT were compared to the maximum standardized uptake values (SUV(max)) in the meningiomas from the PET scans before and after therapy.
  
  
  RESULTS
  The median SUV(max) in the meningiomas was 13.7 (range 4.3 to 68.7), and the maximum fractional radionuclide uptake in voxels of size 0.11 cm³ was a median of 23.4 × 10(-6) (range 0.4 × 10(-6) to 68.3 × 10(-6)). A strong correlation was observed between SUV(max) and the PRRT radionuclide tumour retention in the voxels with the highest uptake (Spearman's rank test, P < 0.01). Excluding one patient who showed large differences in biokinetics between PET and PRRT and another patient with incomplete data, linear regression analysis indicated significant correlations between SUV(max) and the therapeutic uptake (r = 0.95) and between SUV(max) and the maximum voxel dose from PRRT (r = 0.76). Observed absolute deviations from the values expected from regression were a median of 5.6 × 10(-6) (maximum 9.3 × 10(-6)) for the voxel fractional radionuclide uptake and 0.40 Gy per GBq (maximum 0.85 Gy per GBq) (177)Lu for the voxel dose from PRRT.
  
  
  CONCLUSIONS
  PET with (68)Ga-labelled somatostatin analogues allows the pretherapeutic assessment of tumour radionuclide uptake in PRRT of meningioma and an estimate of the achievable dose.
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany. haenscheid_h@klinik.uni-wuerzburg.de
authors.forename: Heribert
authors.initials: H
authors.lastname: Hänscheid
authors.forename: Reinhart A
authors.initials: RA
authors.lastname: Sweeney
authors.forename: Michael
authors.initials: M
authors.lastname: Flentje
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Buck
authors.forename: Mario
authors.initials: M
authors.lastname: Löhr
authors.forename: Samuel
authors.initials: S
authors.lastname: Samnick
authors.forename: Michael
authors.initials: M
authors.lastname: Kreissl
authors.forename: Frederik A
authors.initials: FA
authors.lastname: Verburg
mesh_terms: D000328:Adult; D000368:Aged; D001692:Biological Transport; D005260:Female; D005710:Gallium Radioisotopes / Q000378:metabolism; D006801:Humans; D008297:Male; D008579:Meningioma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy*; D008875:Middle Aged; D058990:Molecular Targeted Therapy; D015282:Octreotide / Q000031:analogs & derivatives / Q000627:therapeutic use; D009942:Organometallic Compounds / Q000627:therapeutic use; D049268:Positron-Emission Tomography; D017481:Receptors, Somatostatin / Q000378:metabolism*; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D005710:Gallium Radioisotopes; D009942:Organometallic Compounds; D017481:Receptors, Somatostatin; D013004:Somatostatin; C447941:lutetium Lu 177 dotatate; D015282:Octreotide; C106246:Edotreotide