Hybrid cardiac PET/MR: the value of multiparametric assessment in cardiac sarcoidosis

Comparing the diagnostic performance of [18F]FDG PET/CT and [18F]FDG PET/MRI for detecting cardiac sarcoidosis: A meta-analysis

PURPOSE

This meta-analysis aimed to evaluate the comparative diagnostic efficacy of [18F]FDG PET/CT and [18F]FDG PET/MRI in detecting cardiac sarcoidosis.

METHODS

An extensive search was conducted in the PubMed and Embase databases to identify available publications up to November 2023. Studies were included if they evaluated the diagnostic efficacy of [18F]FDG PET/CT and [18F]FDG PET/MRI in patients with cardiac sarcoidosis. Sensitivity and specificity were evaluated using the DerSimonian and Laird method, with subsequent transformation via the Freeman-Tukey double inverse sine transformation. Publication bias was assessed using funnel plots and Egger's test.

RESULTS

16 articles involving 1361 patients were included in the meta-analysis. The overall sensitivity of [18F]FDG PET/CT in detecting cardiac sarcoidosis was 0.77(95%CI: 0.62-0.89), while the overall sensitivity of [18F]FDG PET/MRI was 0.94(95%CI: 0.84-1.00). The result indicated that [18F]FDG PET/MRI appears to a higher sensitivity in comparison to [18F]FDG PET/CT(P = 0.02). In contrast, the overall specificity of [18F]FDG PET/CT in detecting cardiac sarcoidosis was 0.90(95%CI: 0.85-0.94), while the overall specificity of [18F]FDG PET/MRI was 0.79(95%CI: 0.53-0.96), with no significant difference in specificity (P = 0.32).

CONCLUSIONS

Our meta-analysis indicates that [18F]FDG PET/MRI demonstrates superior sensitivity and comparable specificity to [18F]FDG PET/CT in detecting cardiac sarcoidosis. However, the small number of PET/MRI studies limited the evidence of current results. To validate these results, larger, prospective studies employing a head-to-head design are needed.

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 18F-fluorodeoxyglucose (18F-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 classified based on the presence/absence of LGE (MR+/MR-), presence/absence of 18F-FDG (PET+/PET-), and pattern of 18F-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 classified MR positivity based on %LGE exceeding 5.7% as MR(+/-)5.7%. Quantitative values of standard uptake value, target-to-background 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-defibrillator (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 classifications (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 receiver-operating 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 classification of CS was statistically associated with clinical outcomes in CS. TNMRmax had modest sensitivity and specificity for quantifying the imaging-based classification MR(+)PET(+)FOCAL and was associated with outcomes. Use of combined MR and PET image-based classification may have use in prognostication and treatment management in CS.