title: Complete somatostatin-induced insulin suppression combined with heparin loading does not significantly suppress myocardial 18F-FDG uptake in patients with suspected cardiac sarcoidosis.
abstract: BACKGROUND
  Cardiac 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography preceded by extended fasting is used to demonstrate active cardiac sarcoidosis. However, physiological insulin-dependent myocardial 18F-FDG uptake often obscures 18F-FDG uptake in sarcoid lesions. We therefore aimed to completely suppress physiological myocardial 18F-FDG uptake by pharmaceutically blocking endogenous insulin secretion while elevating free fatty acids (FFAs).
  
  
  RESULTS
  Six patients with suspected cardiac sarcoidosis were studied in a randomized cross-over design: (1) 12 hours fasting followed by 2 hours saline infusion (SALINE), and (2) 12 hours fasting followed by 2 hour infusions of somatostatin (300 μg/hour) and heparin (70 mIE/kg/minutes) (SOMA). 18F-FDG PET scans were performed post-infusion. Glucose, insulin, and FFA levels were measured and left ventricle SUV-values were recorded. During the SALINE infusion, insulin, glucose, and FFAs remained stable. By design, the SOMA infusions rapidly (<60 minutes) suppressed insulin completely, while FFA levels peaked at 1.13 ± 0.23 mM. However, SOMA infusions only suppressed cardiac 18F-FDG uptake insignificantly globally [SUVmean (g/mL): 4.0 ± 3.3 (SALINE) vs 2.4 ± 1.2 (SOMA), P = .15] and regionally.
  
  
  CONCLUSIONS
  Complete insulin suppression combined with markedly increased circulating FFAs does not completely suppress physiological myocardial 18F-FDG uptake and thus conveys no extra diagnostic value compared with extended fasting.
authors.affiliation: Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark, lars.christian.gormsen@ki.au.dk.
authors.forename: Lars C
authors.initials: LC
authors.lastname: Gormsen
authors.forename: Nana Louise
authors.initials: NL
authors.lastname: Christensen
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bendstrup
authors.forename: Lars Poulsen
authors.initials: LP
authors.lastname: Tolbod
authors.forename: Søren Steen
authors.initials: SS
authors.lastname: Nielsen
mesh_terms: D000328:Adult; D000368:Aged; D009202:Cardiomyopathies / Q000000981:diagnostic imaging*; D018592:Cross-Over Studies; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D019788:Fluorodeoxyglucose F18; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012507:Sarcoidosis / Q000000981:diagnostic imaging*; D013004:Somatostatin / Q000494:pharmacology*
chemical_list: D005230:Fatty Acids, Nonesterified; D007328:Insulin; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013004:Somatostatin; D006493:Heparin