title: Osseous metastases of gastro-enteropancreatic neuroendocrine tumours. Diagnostic value of intra-therapeutic 177Lu-octreotate imaging in comparison with bone scintigraphy.
abstract: OBJECTIVE
  Peptide receptor radionuclide therapy with 177Lu-octreotate is an effective treatment option for metastatic gastroenteropancreatic neuroendocrine tumors (GEP NET) and allows intratherapeutic imaging through a 177Lu-octreotate scan (LuS). The diagnostic value of this treatment scan is not yet established. This study aims to compare the sensitivity of LuS and bone scintigraphy (BS) regarding bone metastases and investigate potential implications of functional imaging results.
  
  
  METHODS
  We retrospectively analyzed 29 consecutive GEP NET patients with bone metastases and baseline BS treated with 177Lu-octreotate. A semi-quantitative scoring system was used for the comparative evaluation. Treatment outcome (time-to-progression of bone metastases) was correlated with the intra-individual imaging discrepancy (Kaplan-Meyer curves, log-rank test, p < 0.05).
  
  
  RESULTS
  In 19 of 29 patients (65.5%) LuS was superior (LuS > BS), whereas in 10 patients (34.5%) both modalities were comparable. BS showed no additional (LuS-negative) metastatic bone lesions in our cohort. None of the investigated baseline characteristics was associated with imaging discrepancy. On the other hand, functional imaging discrepancy had no impact on treatment response (p = 0.43) or time-to-progression (p = 0.92).
  
  
  CONCLUSIONS
  Intra-therapeutic 177Lu-octreotate imaging is superior over bone scintigraphy for detection of bone metastases in GEP NET. BS may help to distinguish osseous from non-osseous localization. The presence of an osteoblastic correlate in BS seems to have no impact on therapeutic outcome.
authors.affiliation: Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Sabet
authors.forename: S
authors.initials: S
authors.lastname: Ezziddin
authors.forename: F
authors.initials: F
authors.lastname: Heinemann
authors.forename: S
authors.initials: S
authors.lastname: Guhlke
authors.forename: M
authors.initials: M
authors.lastname: Muckle
authors.forename: W
authors.initials: W
authors.lastname: Willinek
authors.forename: H-J
authors.initials: HJ
authors.lastname: Biersack
authors.forename: H
authors.initials: H
authors.lastname: Ahmadzadehfar
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary*; D004164:Diphosphonates; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary*; D015282:Octreotide / Q000031:analogs & derivatives* / Q000627:therapeutic use; D015609:Organotechnetium Compounds; D011379:Prognosis; D011877:Radionuclide Imaging / Q000379:methods; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: C554548:177Lu-octreotate; D004164:Diphosphonates; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C033905:technetium Tc 99m 1,1-diphosphonopropane-2,3-dicarboxylic acid; D015282:Octreotide