Comparative Analysis of Myocardial Viability Multimodality Imaging in Patients with Previous Myocardial Infarction and Symptomatic Heart Failure

Impact of CT attenuation correction on viable myocardium detection in combined SPECT and PET/CT: A retrospective cohort study

The influence of computed tomography attenuation correction (CTAC) on the accuracy of diagnosing viable myocardium using Tc-99m-MIBI dedicated cardiac cadmium-zinc-telluride (CZT) single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) combined with F-18-FDG Positron Emission Tomography/Computed Tomography (PET/CT) metabolic imaging, compared with conventional SPECT MPI, remains to be fully elucidated. To evaluate the impact of CTAC on the accuracy of diagnosing viable myocardium using Tc-99m-MIBI dedicated cardiac CZT SPECT MPI combined with F-18-FDG PET/CT, compared to conventional SPECT MPI. 193 patients underwent CZT SPECT and F-18-FDG PET/CT imaging, while 39 patients underwent conventional SPECT and F-18-FDG PET/CT imaging, with both groups utilizing CT for attenuation correction. The injured myocardium (hibernating and scarring) was quantified using the Q.PET software. After CTAC, both groups showed significant improvements in perfusion of the injured myocardial areas, particularly in the inferior wall (INF). The reduction in perfusion was more notable in the CZT SPECT group than that in the conventional group, particularly in the inferior and lateral walls. Among patients with large cardiac chambers, those undergoing MPI with CZT, with normal weights, or males, hibernating myocardium (HM) and scar post-CTAC reductions were particularly significant in the INF. If HM ≥ 10% is considered an indicator for recommended revascularization, among the 87 patients without prior cardiac bypass, 25 (28.7%) might not require revascularization treatment. Dedicated cardiac CZT SPECT and conventional SPECT MPI combined with F-18-FDG PET/CT significantly influenced the assessment of viable myocardium. The impact of CTAC was more profound in dedicated cardiac CZT SPECT, particularly in the INF region. CTAC significantly enhances the accuracy of viable myocardial assessment and may influence clinical decisions regarding revascularization therapy. Therefore, CTAC should be routinely used in dedicated cardiac CZT SPECT MPI combined with F-18-FDG PET/CT for myocardial viability diagnosis.

A Feasibility Study of [18F]F-AraG Positron Emission Tomography (PET) for Cardiac Imaging-Myocardial Viability in Ischemia-Reperfusion Injury Model

PURPOSE

Myocardial infarction (MI) with subsequent inflammation is one of the most common heart conditions leading to progressive tissue damage. A reliable imaging marker to assess tissue viability after MI would help determine the risks and benefits of any intervention. In this study, we investigate whether a new mitochondria-targeted imaging agent, 18F-labeled 2'-deoxy-2'-18F-fluoro-9-β-d-arabinofuranosylguanine ([18F]F-AraG), a positron emission tomography (PET) agent developed for imaging activated T cells, is suitable for cardiac imaging and to test the myocardial viability after MI.

PROCEDURE

To test whether the myocardial [18F]-F-AraG signal is coming from cardiomyocytes or immune infiltrates, we compared cardiac signal in wild-type (WT) mice with that of T cell deficient Rag1 knockout (Rag1 KO) mice. We assessed the effect of dietary nucleotides on myocardial [18F]F-AraG uptake in normal heart by comparing [18F]F-AraG signals between mice fed with purified diet and those fed with purified diet supplemented with nucleotides. The myocardial viability was investigated in rodent model by imaging rat with [18F]F-AraG and 2-deoxy-2[18F]fluoro-D-glucose ([18F]FDG) before and after MI. All PET signals were quantified in terms of the percent injected dose per cc (%ID/cc). We also explored [18F]FDG signal variability and potential T cell infiltration into fibrotic area in the affected myocardium with H&E analysis.

RESULTS

The difference in %ID/cc for Rag1 KO and WT mice was not significant (p = ns) indicating that the [18F]F-AraG signal in the myocardium was primarily coming from cardiomyocytes. No difference in myocardial uptake was observed between [18F]F-AraG signals in mice fed with purified diet and with purified diet supplemented with nucleotides (p = ns). The [18F]FDG signals showed wider variability at different time points. Noticeable [18F]F-AraG signals were observed in the affected MI regions. There were T cells in the fibrotic area in the H&E analysis, but they did not constitute the predominant infiltrates.

CONCLUSIONS

Our preliminary preclinical data show that [18F]F-AraG accumulates in cardiomyocytes indicating that it may be suitable for cardiac imaging and to evaluate the myocardial viability after MI.

The incremental value of myocardial viability, evaluated by 18F-fluorodeoxyglucose positron emission tomography, and cardiovascular magnetic resonance for mortality prediction in patients with previous myocardial infarction and symptomatic heart failure

OBJECTIVES

To find the imaging mortality predictors in patients with previous myocardial infarction (MI), symptomatic heart failure (HF), and reduced left ventricle (LV) ejection fraction (EF).

METHODS

for the study 39 patients were selected prospectively with prior MI, symptomatic HF, and LVEF ≤40%. All patients underwent transthoracic echocardiography (TTE), single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI), 18F-FDG positron emission tomography (FDG PET). 31 patients underwent cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE). Patients were divided into two groups: 1 group - cardiac death; 2 group - no cardiac death. Myocardial scars were assessed on a 5-point-scale. Follow-up data was obtained.

RESULTS

Imaging features disclosed significant difference (p < 0.05) of defect score (CMR and SPECT-PET), LV end-diastolic diameter (EDD) (TTE), LVEDD index (CMR), LV global longitudinal strain (CMR) and LV global circumferential strain (CMR) between the groups. Predictors of cardiac death were: LVEDD index (TTE) and LV global longitudinal strain. The cut-off values to predict cardiac death were: defect score (CMR) 25 (AUC, 79.5%; OR 1.8, 95% CI 1.2-2.7), SPECT-PET defect score 22 (AUC, 73.9%; OR 0.5, 95% CI 0.3-0.7), LVEDD (TTE) 58 mm (AUC, 88.4%; OR 23.6, 95% CI 2.6-217.7), LVEDDi 30 mm/m2 (TTE) (AUC, 73.6%; OR 22.0, 95% CI 1.9-251.5), LVEDDi 33.6 mm/m2 (CMR) (AUC, 73.6%; OR 22.0, 95% CI 1.9-251.5), LV global longitudinal strain -13.4 (AUC, 87.8%; OR 2.1, 95% CI 1.2-3.7) and LV global circumferential strain -16.3 (AUC, 76.1%; OR 1.9, 95% CI 1.2-3.0).

CONCLUSIONS

Imaging features, such as defect score (CMR) >25, SPECT-PET defect score >22, LVEDD (TTE) >58 mm, LVEDDi (TTE) >30 mm/m2, LVEDDi (CMR) >33.6 mm/m2, LV global longitudinal strain -13.4 and LV global circumferential strain -16.3, may increase sensitivity and specificity of FDG PET and LGE CMR predicting of late mortality.

Myocardial Viability Testing in the Management of Ischemic Heart Failure

Although major advances have occurred lately in medical therapy, ischemic heart failure remains an important cause of death and disability. Viable myocardium represents a cause of reversible ischemic left ventricular dysfunction. Coronary revascularization may improve left ventricular function and prognosis in patients with viable myocardium. Although patients with impaired left ventricular function and multi-vessel coronary artery disease benefit the most from revascularization, they are at high risk of complications related to revascularization procedure. An important element in selecting the patients for myocardial revascularization is the presence of the viable myocardium. Multiple imaging modalities can assess myocardial viability and predict functional improvement after revascularization, with dobutamine stress echocardiography, nuclear imaging tests and magnetic resonance imaging being the most frequently used. However, the role of myocardial viability testing in the management of patients with ischemic heart failure is still controversial due to the failure of randomized controlled trials of revascularization to reveal clear benefits of viability testing. This review summarizes the current knowledge regarding the concept of viable myocardium, depicts the role and tools for viability testing, discusses the research involving this topic and the controversies related to the utility of myocardial viability testing and provides a patient-centered approach for clinical practice.