Hybrid Magnetic Resonance Positron Emission Tomography is Associated with Cardiac-Related Outcomes in Cardiac Sarcoidosis.

BACKGROUND Imaging with late gadolinium enhancement (LGE) magnetic resonance (MR) and 18 F- fluorodeoxyglu- cose ( 18 F-FDG) PET allows complementary assessment of myocardial injury and disease activity and has shown promise for improved characterization of active cardiac sarcoidosis (CS) based on the combined positive imaging outcome, MR(+)PET(+). OBJECTIVES This study aims to evaluate qualitative and quantitative assessments of hybrid MR/PET imaging in CS and to evaluate its association with cardiac -related outcomes. METHODS A total of 148 patients with suspected CS underwent hybrid MR/PET imaging. Patients were classi fied based on the presence/absence of LGE (MR+/MR-), presence/absence of 18 F-FDG (PET+/PET-), and pattern of 18 F-FDG uptake (focal/diffuse) into the following categories: MR(+)PET(+) FOCAL , MR(+)PET(+) DIFFUSE , MR(+)PET(-), MR(-)PET(+) FOCAL , MR( - )PET(+) DIFFUSE , MR( -)PET(-). Further analysis classi fied MR positivity based on %LGE exceeding 5.7% as MR(+/ -) 5.7% . Quantitative values of standard uptake value, target -tobackground ratio, target -to -normal -myocardium ratio (TNMRmax), and T2 were measured. The primary clinical endpoint was met by the occurrence of cardiac arrest, ventricular tachycardia, or secondary prevention implantable cardioverter-de fibrillator (ICD) before the end of the study. The secondary endpoint was met by any of the primary endpoint criteria plus heart failure or heart block. MR/PET imaging results were compared between those meeting or not meeting the clinical endpoints. RESULTS Patients designated MR(+) 5.7% PET(+) FOCAL had increased odds of meeting the primary clinical endpoint compared to those with all other imaging classi fications (unadjusted OR: 9.2 [95% CI: 3.0-28.7]; P = 0.0001), which was higher than the odds based on MR or PET alone. TNMRmax achieved an area under the receiveroperating characteristic curve of 0.90 for separating MR(+)PET(+) FOCAL from non-MR(+)PET(+) FOCAL , and 0.77 for separating those reaching the clinical endpoint from those not reaching the clinical endpoint. CONCLUSIONS Hybrid MR/PET image -based classi fication of CS was statistically associated with clinical outcomes in CS. TNMRmax had modest sensitivity and speci ficity for quantifying the imaging -based classi fication MR(+)PET(+) FOCAL and was associated with outcomes. Use of combined MR and PET image -based classi fication may have use in prognostication and treatment management in CS. (J Am Coll Cardiol Img 2024;17:411 -424) (c) 2024 Published by Elsevier on behalf of the American College of Cardiology Foundation.