Somatostatin receptor based PET/CT in patients with the suspicion of cardiac sarcoidosis: an initial comparison to cardiac MRI

Abstract

// Constantin Lapa 1, * , Theresa Reiter 2, 3, * , Malte Kircher 1 , Andreas Schirbel 1 , Rudolf A. Werner 1 , Theo Pelzer 2 , Carmen Pizarro 4 , Dirk Skowasch 4 , Lena Thomas 5 , Ulrike Schlesinger-Irsch 6 , Daniel Thomas 6 , Ralph A. Bundschuh 5 , Wolfgang R. Bauer 2, 3, * , Florian C. Gärtner 5, * 1 Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany 2 Department of Internal Medicine, University Hospital Würzburg, Würzburg, Germany 3 Comprehensive Heart Failure Center, University Würzburg, Würzburg, Germany 4 Department of Internal Medicine II - Pneumology/Cardiology, University Hospital Bonn, Bonn, Germany 5 Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany 6 Department of Radiology, University Hospital Bonn, Bonn, Germany * These authors have contributed equally to this work Correspondence to: Constantin Lapa, email: lapa_c@ukw.de Keywords: sarcoidosis, DOTATOC, SSTR, somatostatin receptor, PET Received: September 01, 2016      Accepted: October 12, 2016      Published: October 21, 2016 ABSTRACT Diagnosis of cardiac sarcoidosis is often challenging. Whereas cardiac magnetic resonance imaging (CMR) and positron emission tomography/computed tomography (PET/CT) with 18 F-fluorodeoxyglucose (FDG) are most commonly used to evaluate patients, PET/CT using radiolabeled somatostatin receptor (SSTR) ligands for visualization of inflammation might represent a more specific alternative. This study aimed to investigate the feasibility of SSTR–PET/CT for detecting cardiac sarcoidosis in comparison to CMR. 15 patients (6 males, 9 females) with sarcoidosis and suspicion on cardiac involvement underwent SSTR-PET/CT imaging and CMR. Images were visually scored. The AHA 17-segment model of the left myocardium was used for localization and comparison of inflamed myocardium for both imaging modalities. In semi-quantitative analysis, mean (SUV mean ) and maximum standardized uptake values (SUV max ) of affected myocardium were calculated and compared with both remote myocardium and left ventricular (LV) cavity. SSTR-PET was positive in 7/15, CMR in 10/15 patients. Of the 3 CMR + /PET - subjects, one patient with minor involvement (<25% of wall thickness in CMR) was missed by PET. The remaining two CMR + /PET - patients displayed no adverse cardiac events during follow-up. In the 17-segment model, PET/CT yielded 27 and CMR 29 positive segments. Overall concordance of the 2 modalities was 96.1% (245/255 segments analyzed). SUV mean and SUV max in inflamed areas were 2.0±1.2 and 2.6±1.2, respectively. The lesion-to-remote myocardium and lesion-to-LV cavity ratios were 1.8±0.2 and 1.9±0.2 for SUV mean and 2.0±0.3 and 1.7±0.3 for SUV max , respectively. Detection of cardiac sarcoidosis by SSTR-PET/CT is feasible. Our data warrant further analysis in larger prospective series.