RT Journal Article
SR Electronic
T1 Usefulness of combined FDG-PET/MR to diagnose active cardiac sarcoidosis.
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1668
OP 1668
VO 57
IS supplement 2
A1 Ronan Abgral
A1 Marc Dweck
A1 Philip Robson
A1 Maria Trivieri
A1 Nicolas Karakatsanis
A1 Javier Sanz
A1 Johanna Contreras
A1 Valentin Fuster
A1 Maria Padilla
A1 Jason Kovacic
A1 Zahi Fayad
YR 2016
UL http://jnm.snmjournals.org/content/57/supplement_2/1668.abstract
AB 1668Objectives Sarcoidosis is a granulomatous disease of unknown etiology that most commonly affects lung and mediastinal lymph nodes. Heart involvement is probably under-diagnosed due to frequent absence of clinical symptoms but poses an increased risk of sudden death. A major current obstacle is the inability to easily diagnose cardiac sarcoidosis (CS) with a non-invasive method. Several imaging techniques are already used to assess CS including myocardial inflammatory activity using 18F-fluorodesoxyglucose (FDG) Positron Emission Tomography (PET) and the pattern of injury using Magnetic Resonance (MR) with late Gadolinium enhancement (LGE). Recent advances now allow combining these 2 techniques to benefit from the best of these modalities. Our aim was to assess the usefulness of FDG-PET/MR in the diagnosis of CS.Methods Patients with clinical suspicion of cardiac sarcoid involvement were referred in our department for PET/MR imaging (Biograph mMR, Siemens®). Institutional Review Board approved this study and all patients gave written informed consent. PET data were reconstructed using a MR attenuation correction map. Image analysis was performed using 3 methods on fused PET-MR data sets: 1) No correction: maximal standardized uptake value (SUVmax) in the myocardium was recorded; 2) Blood-pool correction: maximum myocardial SUV value was corrected for blood pool measurement in the right ventricular cavity (TBRmax = SUVmax / blood pool uptake; 3) Myocardial correction: maximum myocardial SUV value was corrected for PET activity in the opposing myocardial segment (TNRmax = SUVmax / maximal uptake in a contra-lateral area). A final diagnosis of active cardiac sarcoidosis (CS+) or no active (CS-) was defined by a consensus of clinical experts with access to all clinical, imaging and biopsy data. Mean SUVmax, TBRmax and TNRmax in CS+ and CS- patients were compared using a Student t-test.Results Thirteen consecutive patients (7M/6F; 55.9 ± 12.3 yo) were included from August to November 2015. One of them did not perform the exam due to claustrophobia. All others underwent PET/MR 70.2 ± 5.4 min after injection of 4.7 ± 0.3 MBq/Kg of FDG. Four patients were considered as CS+ and 8 as CS- by the expert panel. Mean SUVmax were respectively 4.22 ± 1.81 and 3.14 ± 2.11 in CS+ and in CS- patients (p = 0.404). Mean TBRmax were respectively 1.98 ± 0.55 and 1.55 ± 1.08 in CS+ and in CS- patients (p = 0.431). Mean TNRmax were respectively 1.79 ± 0.48 and 1.08 ± 0.05 in CS+ and in CS- patients (p = 0.001). A clear threshold of TNRmax = 1.2 accurately differentiated all patients as being CS+ or CS-. One previously unknown case of sarcoid involvement in bone was also identified. In the CS- group, combined FDG-PET/MR identified an alternative cause for the cardiac symptoms in 3 patients (1 arrhythmogenic right ventricular cardiomyopathy, 1 incidental chronic infarction, 1 aortic valve fibroelastoma).Conclusions These preliminary results of our prospective study show the usefulness of combined FDG-PET/MR in the diagnosis of CS using TNRmax measurements. Further inclusions of patients are needed to validate an optimal threshold of TNRmax and verify the clinical utility of combined FDG-PET/MR. This series also confirms the ability of PET/MR imaging to evaluate extra-cardiac involvement of sarcoidosis and in assessing alternative myocardial pathologies.