A dual tracer (68)Ga-DOTANOC PET/CT and (18)F-FDG PET/CT pilot study for detection of cardiac sarcoidosis.
BACKGROUND
Cardiac sarcoidosis (CS) is a potentially fatal condition lacking a single test with acceptable diagnostic accuracy. (18)F-FDG PET/CT has emerged as a promising imaging modality, but is challenged by physiological myocardial glucose uptake. An alternative tracer, (68)Ga-DOTANOC, binds to somatostatin receptors on inflammatory cells in sarcoid granulomas. We therefore aimed to conduct a proof-of-concept study using (68)Ga-DOTANOC to diagnose CS. In addition, we compared diagnostic accuracy and inter-observer variability of (68)Ga-DOTANOC vs. (18)F-FDG PET/CT.


METHODS
Nineteen patients (seven female) with suspected CS were prospectively recruited and dual tracer scanned within 7 days. PET images were reviewed by four expert readers for signs of CS and compared to the reference standard (Japanese ministry of Health and Welfare CS criteria).


RESULTS
CS was diagnosed in 3/19 patients. By consensus, 11/19 (18)F-FDG scans and 0/19 (68)Ga-DOTANOC scans were rated as inconclusive. The sensitivity of (18)F-FDG PET for diagnosing CS was 33 %, specificity was 88 %, PPV was 33 %, NPV was 88 %, and diagnostic accuracy was 79 %. For (68)Ga-DOTANOC, accuracy was 100 %. Inter-observer agreement was poor for (18)F-FDG PET (Fleiss' combined kappa 0.27, NS) and significantly better for (68)Ga-DOTANOC (Fleiss' combined kappa 0.46, p = 0.001).


CONCLUSIONS
Despite prolonged pre-scan fasting, a large proportion of (18)F-FDG PET/CT images were rated as inconclusive, resulting in low agreement among reviewers and correspondingly poor diagnostic accuracy. By contrast, (68)Ga-DOTANOC PET/CT had excellent diagnostic accuracy with the caveat that inter-observer variability was still significant. Nevertheless, (68)Ga-DOTANOC PET/CT looks very promising as an alternative CS PET tracer.


BACKGROUND
Current Controlled Trials NCT01729169 .
Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark. lars.christian.gormsen@clin.au.dk.
Lars C
http://orcid.org/0000-0001-6937-704X
LC
Gormsen
Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark.
Ate
A
Haraldsen
Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark.
Stine
S
Kramer
Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark.
Andre H
AH
Dias
Department of Cardiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark.
Won Yong
WY
Kim
Department of Nuclear Medicine & PET Center, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark.
Per
P
Borghammer
Cardiac sarcoidosis; Heart failure; Inflammation; PET/CT; Somatostatin receptor imaging