title: Evaluation of semi-quantitative scoring system for metaiodobenzylguanidine (mIBG) scans in patients with relapsed neuroblastoma.
abstract: BACKGROUND
  The purpose of this study was to determine the accuracy of two semi-quantitative scoring systems to assess response to (131)I-metaiodobenzylguanidine (mIBG) therapy in recurrent neuroblastoma.
  
  
  METHODS
  Diagnostic mIBG scan pairs (n = 57) were collected for patients who underwent (131)I-mIBG therapy for relapsed neuroblastoma. Two scoring systems were designated: Method 1, which divided the body into nine segments to view osteomedullary lesions with an additional tenth segment to assess soft tissue involvement; and Method 2, which divided the body into seven segments without a corresponding compartment for soft tissue involvement. Four nuclear medicine physicians independently assigned extension and intensity scores utilizing both methods, and separately recorded their impression of whether the post-therapy scan had improved, not changed, or worsened. Inter- and intra-observer concordance and correlation with overall response and progression-free survival (PFS) were performed.
  
  
  RESULTS
  Method 1 produced the highest inter-observer concordance and was used to calculate the relative extension scores (post-therapy score divided by pre-therapy score), which correlated significantly with overall response. Patients who achieved complete response (CR) or partial response (PR) (n = 21) had lower relative extension scores, compared to those without response (P < 0.001). The readers' overall impression associated highly (P < 0.001) with the relative extension scores though results were less quantitative. Concordance was higher if initial scores were >5. Relative extension score did not predict PFS.
  
  
  CONCLUSIONS
  Semi-quantitative scoring of mIBG scans provides a more reliable method of assessing response in patients with relapsed neuroblastoma than qualitative impression. The reproducibility and high inter-observer concordance makes mIBG score an important component of overall response criteria in patients with recurrent neuroblastoma.
authors.affiliation: Department of Pediatrics, University of California, San Francisco, California 94143, USA.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Messina
authors.forename: Su-Chun
authors.initials: SC
authors.lastname: Cheng
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Franc
authors.forename: Martin
authors.initials: M
authors.lastname: Charron
authors.forename: Barry
authors.initials: B
authors.lastname: Shulkin
authors.forename: Bao
authors.initials: B
authors.lastname: To
authors.forename: John M
authors.initials: JM
authors.lastname: Maris
authors.forename: Gregory
authors.initials: G
authors.lastname: Yanik
authors.forename: Randall A
authors.initials: RA
authors.lastname: Hawkins
authors.forename: Katherine K
authors.initials: KK
authors.lastname: Matthay
mesh_terms: D019797:3-Iodobenzylguanidine; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009364:Neoplasm Recurrence, Local; D009447:Neuroblastoma / Q000000981:diagnostic imaging* / Q000401:mortality; D015588:Observer Variation; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine