title: Usefulness of fasting 18F-FDG PET in identification of cardiac sarcoidosis.
abstract: Cardiac PET using (18)F-FDG under fasting conditions (fasting (18)F-FDG PET) is a promising technique for identification of cardiac sarcoidosis and assessment of disease activity. The aim of this study was to investigate the usefulness of fasting (18)F-FDG PET in detecting inflammatory lesions of cardiac sarcoidosis from a pathophysiologic standpoint.
  
  
  METHODS
  Twenty-two patients with systemic sarcoidosis were classified into 2 groups of 11 each according to the presence or absence of sarcoid heart disease. Cardiac sarcoidosis was diagnosed according to the Japanese Ministry of Health and Welfare guidelines for diagnosing cardiac sarcoidosis with the exception of scintigraphic criteria. Nuclear cardiac imaging with fasting (18)F-FDG PET, (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) SPECT, and (67)Ga scintigraphy were performed in all patients. PET and SPECT images were divided into 13 myocardial segments and the standardized uptake value (SUV) of (18)F-FDG was calculated and defect scores (DS) for (99m)Tc-MIBI uptake were assessed for each segment. The total SUV (T-SUV) and total DS (TDS) were calculated as the sum of measurements for all 13 segments, and the diagnostic accuracy of fasting (18)F-FDG PET was compared with that of the other nuclear imaging modalities. In addition, pathophysiologic relationships between inflammatory activity and myocardial damage were examined by segmental comparative study using the SUV and DS.
  
  
  RESULTS
  In patients with cardiac sarcoidosis, fasting (18)F-FDG PET revealed a higher frequency of abnormal myocardial segments than (99m)Tc-MIBI SPECT (mean number of abnormal segments per patient: 6.6 +/- 3.0 vs. 3.0 +/- 3.2 [mean +/- SD], P < 0.05). The sensitivity of fasting (18)F-FDG PET in detecting cardiac sarcoidosis was 100%, significantly higher than that of (99m)Tc-MIBI SPECT (63.6%) or (67)Ga scintigraphy (36.3%). The accuracy of fasting (18)F-FDG PET was significantly higher than (67)Ga scintigraphy. The T-SUV demonstrated a good linear correlation with serum angiotensin-converting enzyme levels (r = 0.83, P < 0.01), and the TDS showed a significant negative correlation with the left ventricular ejection fraction (r = -0.82, P < 0.01). In abnormal myocardial segments on the nuclear scan, the SUV showed a significant negative correlation with the DS (r = -0.63, P < 0.0001).
  
  
  CONCLUSIONS
  This study suggests that fasting (18)F-FDG PET can detect the early stage of cardiac sarcoidosis, in which fewer perfusion abnormalities and high inflammatory activity are noted, before advanced myocardial impairment.
authors.affiliation: Second Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan. wokumura-circ@umin.ac.jp
authors.forename: Wataru
authors.initials: W
authors.lastname: Okumura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Takuji
authors.initials: T
authors.lastname: Toyama
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Iso
authors.forename: Masashi
authors.initials: M
authors.lastname: Arai
authors.forename: Noboru
authors.initials: N
authors.lastname: Oriuchi
authors.forename: Keigo
authors.initials: K
authors.lastname: Endo
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kurabayashi
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D005215:Fasting; D005260:Female; D019788:Fluorodeoxyglucose F18; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D012507:Sarcoidosis / Q000000981:diagnostic imaging*; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D001786:Blood Glucose; D019788:Fluorodeoxyglucose F18; D017256:Technetium Tc 99m Sestamibi