title: Low-dose (123)I-metaiodobenzylguanidine diagnostic scan is inferior to (131)I-metaiodobenzylguanidine posttreatment scan in detection of malignant pheochromocytoma and paraganglioma.
abstract: OBJECTIVE
  We assessed the lesion detectability of low-dose diagnostic (123)I-metaiodobenzylguanidine (MIBG) whole-body scans obtained at 6 and 24 h compared with posttreatment (131)I-MIBG whole-body scans in malignant pheochromocytoma and paraganglioma.
  
  
  METHODS
  Scintigrams obtained in 15 patients with malignant pheochromocytoma and paraganglioma were retrospectively analyzed. Diagnostic scans were performed with 111 MBq of (123)I-MIBG. Therapeutic doses of (131)I-MIBG (5.55-7.40 GBq) were administrated and whole-body scans were obtained at 2-5 days after (131)I-MIBG administrations. We compared the number of lesions and the lesion-to-referent count ratios at 6 and 24 h of (123)I-MIBG and at 2-5 days of (131)I-MIBG.
  
  
  RESULTS
  In comparison with the 6-h images of (123)I-MIBG, the 24-h images of (123)I-MIBG could detect more lesions in eight patients. Posttreatment (131)I-MIBG scans revealed new lesions in eight patients compared with the 24-h images of (123)I-MIBG. The lesion-to-referent count ratios at 6 and 24 h of (123)I-MIBG and at 3 days of (131)I-MIBG were increasing at later scanning time. There were significant differences in the lesion-to-referent count ratios between 6 and 24 h of (123)I-MIBG (P = 0.031), 6 h of (123)I-MIBG and 3 days of (131)I-MIBG (P = 0.020), and 24 h of (123)I-MIBG and 3 days of (131)I-MIBG (P = 0.018).
  
  
  CONCLUSIONS
  Low-dose diagnostic (123)I-MIBG whole-body scan is inferior to posttreatment (131)I-MIBG whole-body scan in malignant pheochromocytoma and paraganglioma. Considering the scan timing of (123)I-MIBG, 6-h images might have no superiority compared with 24-h images.
authors.affiliation: Department of Nuclear Medicine, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan. kayano@nmd.m.kanazawa-u.ac.jp
authors.forename: Daiki
authors.initials: D
authors.lastname: Kayano
authors.forename: Junichi
authors.initials: J
authors.lastname: Taki
authors.forename: Makoto
authors.initials: M
authors.lastname: Fukuoka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wakabayashi
authors.forename: Anri
authors.initials: A
authors.lastname: Inaki
authors.forename: Ayane
authors.initials: A
authors.lastname: Nakamura
authors.forename: Seigo
authors.initials: S
authors.lastname: Kinuya
mesh_terms: D019797:3-Iodobenzylguanidine / Q000378:metabolism; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D000328:Adult; D000368:Aged; D001692:Biological Transport; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010235:Paraganglioma / Q000000981:diagnostic imaging* / Q000378:metabolism; D010673:Pheochromocytoma / Q000000981:diagnostic imaging* / Q000378:metabolism; D011829:Radiation Dosage; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D013997:Time Factors; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D019797:3-Iodobenzylguanidine