Prospective Evaluation of ¹⁸ F-Fluorodeoxyglucose Uptake in Postischemic Myocardium by Simultaneous Positron Emission Tomography/Magnetic Resonance Imaging as a Prognostic Marker of Functional Outcome

Abstract

Background The immune system orchestrates the repair of infarcted myocardium. Imaging of the cellular inflammatory response by 18F-FDG PET/MRI in the heart has been demonstrated in preclinical and clinical studies. However, the clinical relevance of post-MI 18F-FDG uptake in the heart has not been elucidated. The objective of this study was to explore the value of 18F-FDG-PET/MRI in patients after AMI as a biosignal for left ventricular functional outcome. Methods and Results We prospectively enrolled 49 patients with STEMI and performed 18F-FDG-PET/MRI 5 days after PCI and follow-up cardiac MRI after 6–9 months. In a subset of patients, 99mTc-sestamibi-SPECT was performed with tracer injection prior to revascularization. Cellular innate immune response was analyzed at multiple time points. Segmental comparison of 18F-FDG-uptake and LGE showed substantial overlap (κ=0.66), while quantitative analysis demonstrated that 18F-FDG extent exceeded LGE extent (33.2±16.2 %LV vs. 20.4±10.6 %LV, p<0.0001) and corresponded to the area-at-risk (r=0.87, p<0.0001). The peripheral blood count of CD14high/CD16+ monocytes correlated with the infarction size and 18F-FDG signal extent (r=0.53, p<0.002 and r=0.42, p<0.02, respectively). 18F-FDG uptake in the infarcted myocardium was highest in areas with transmural scar and the SUVmean was associated with left ventricular functional outcome independent of infarct size (ΔEF: p<0.04, ΔEDV: p<0.02, ΔESV: p<0.005). Conclusions In the current study, the intensity of 18F-FDG uptake in the myocardium after AMI correlated inversely with functional outcome at 6 months. Thus, 18F-FDG uptake in infarcted myocardium may represent a novel biosignal of myocardial injury.

Inflammatory processes in cardiovascular disease: a route to targeted therapies

“…In experimental models of AMI, the application of 18 fluorodeoxyglucose ( 18 FDG) PET in combination with MRI further improved localization of infiltration of metabolically active leukocytes in experimental models 98 , with cellular imaging studies supporting these conclusions 99 . Clinical studies have demonstrated similar findings, which provide the capacity to quantify metabolic activity in the myocardium after infarction 100 , monitor continued disease activity, and might also provide a prognostic marker of functional outcome 101 .…”

Molecular Imaging of Inflammation in Ischemic Heart Disease

“…Unlike mice, inflamed ischemic tissue in humans is often interspersed with normal surviving myocytes, creating a heterogeneous distribution that can confound clinical interpretation. To explore whether 18 F-FDG uptake can be used clinically post MI, Rischpler, et al 56 prospectively evaluated 49 patients with STEMI using 18 F-FDG PET/MRI 5 days after PCI with a follow-up cardiac MRI after 6-9 months. The mean standardized uptake value (SUV mean) of 18 F-FDG was detected in transmural scars and was associated with left ventricular dysfunction independent of infarct size measured by late gadolinium enhancement.…”

A Multimodal Approach to Evaluate for Cardiac Metastasis in a Case of Non-Small Cell Lung Cancer

“…PET-CT is known to be less specific as inflammatory cells will also cause increased FDG avidity, most commonly in the context of infection. However, increased uptake has also been reported in postischemic or infarcted tissue [27][28][29], atherosclerosis [30], physiological papillary muscle [31], hypertrophied papillary muscle [32], and postoperative contexts [32]. To our knowledge, there are no reported cases of chronic mitral regurgitation due to prolapse being a cause of increased FDG avidity.…”