A dual tracer (68)Ga-DOTANOC PET/CT and (18)F-FDG PET/CT pilot study for detection of cardiac sarcoidosis

PET/CT in Inflammatory and Auto-immune Disorders: Focus on Several Key Molecular Concepts, FDG, and Radiolabeled Probe Perspectives

Chronic immune diseases mainly include autoimmune and inflammatory diseases. Managing chronic inflammatory and autoimmune diseases has become a significant public health concern, and therapeutic advancements over the past 50 years have been substantial. As therapeutic tools continue to multiply, the challenge now lies in providing each patient with personalized care tailored to the specifics of their condition, ushering in the era of personalized medicine. Precise and holistic imaging is essential in this context to comprehensively map the inflammatory processes in each patient, identify prognostic factors, and monitor treatment responses and complications. Imaging of patients with inflammatory and autoimmune diseases must provide a comprehensive view of the body, enabling the whole-body mapping of systemic involvement. It should identify key cellular players in the pathology, involving both innate immunity (dendritic cells, macrophages), adaptive immunity (lymphocytes), and microenvironmental cells (stromal cells, tissue cells). As a highly sensitive imaging tool with vectorized molecular probe capabilities, PET/CT can be of high relevance in the management of numerous inflammatory and autoimmune diseases. Relying on key molecular concepts of immunity, the clinical usefulness of FDG-PET/CT in several relevant inflammatory and immune-inflammatory conditions, validated or emerging, will be discussed in this review, together with radiolabeled probe perspectives.

Molecular Imaging of Heart Failure: An Update and Future Trends

Molecular imaging can detect and quantify pathophysiological processes underlying heart failure, complementing evaluation of cardiac structure and function with other imaging modalities. Targeted tracers have enabled assessment of various cellular and subcellular mechanisms of heart failure aiming for improved phenotyping, risk stratification, and personalized therapy. This review outlines the current status of molecular imaging in heart failure, accompanied with discussion on novel developments. The focus is on radionuclide methods with data from clinical studies. Imaging of myocardial metabolism can identify left ventricle dysfunction caused by myocardial ischemia that may be reversible after revascularization in the presence of viable myocardium. In vivo imaging of active inflammation and amyloid deposition have an established role in the detection of cardiac sarcoidosis and transthyretin amyloidosis. Innervation imaging has well documented prognostic value in predicting heart failure progression and arrhythmias. Tracers specific for inflammation, angiogenesis and myocardial fibrotic activity are in earlier stages of development, but have demonstrated potential value in early characterization of the response to myocardial injury and prediction of cardiac function over time. Early detection of disease activity is a key for transition from medical treatment of clinically overt heart failure towards a personalized approach aimed at supporting repair and preventing progressive cardiac dysfunction.

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.

Molecular imaging for evaluation of synovitis associated with osteoarthritis: a narrative review

Recent evidence highlights the role of low-grade synovial inflammation in the progression of osteoarthritis (OA). Inflamed synovium of OA joints detected by imaging modalities are associated with subsequent progression of OA. In this sense, detecting and quantifying synovitis of OA by imaging modalities may be valuable in predicting OA progressors as well as in improving our understanding of OA progression. Of the several imaging modalities, molecular imaging such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) has an advantage of visualizing the cellular or subcellular events of the tissues. Depending on the radiotracers used, molecular imaging method can potentially detect and visualize various aspects of synovial inflammation. This narrative review summarizes the recent progresses of imaging modalities in assessing inflammation and OA synovitis and focuses on novel radiotracers. Recent studies about imaging modalities including ultrasonography (US), magnetic resonance imaging (MRI), and molecular imaging that were used to detect and quantify inflammation and OA synovitis are summarized. Novel radiotracers specifically targeting the components of inflammation have been developed. These tracers may show promise in detecting inflamed synovium of OA and help in expanding our understanding of OA progression.

Use of PET/CT to detect myocardial inflammation and the risk of malignant arrhythmia in chronic Chagas disease

BACKGROUND

Chagas heart disease (CHD) is characterized by progressive myocardial inflammation associated with myocardial fibrosis and segmental abnormalities that may lead to malignant ventricular arrhythmia and sudden cardiac death. This arrhythmia might be related to the persistence of parasitemia or inflammation in the myocardium in late-stage CHD. Positron emission tomography/computed tomography (PET/CT) has been used to detect myocardial inflammation in non-ischemic cardiomyopathies, such as sarcoidosis, and might be useful for risk prediction in patients with CHD.

METHODS AND RESULTS

Twenty-four outpatients with chronic CHD were enrolled in this prospective cross-sectional study between May 2019 and March 2022. The patients were divided into two groups: those with sustained ventricular tachycardia and/or aborted sudden cardiac death who required implantable cardioverter-defibrillators, and those with the same stages of CHD and no complex ventricular arrhythmia. Patients underwent 18F-fluorodeoxyglucose (18F-FDG) and 68Ga-DOTATOC PET/CT, and blood samples were collected for qualitative parasite assessment by polymerase chain reaction. Although similar proportions of patients with and without complex ventricular arrhythmia showed 18F-FDG and 68Ga-DOTATOC uptake, 68Ga-DOTATOC corrected SUVmax was higher in patients with complex arrhythmia (3.4 vs 1.7; P = .046), suggesting that inflammation could be associated with the presence of malignant arrhythmia in the late stages of CHD. We also detected Trypanosoma cruzi in both groups, with a nonsignificant trend of increased parasitemia in the group with malignant arrhythmia (66.7% vs 33.3%).

CONCLUSION

18F-FDG and 68Ga-DOTATOC uptake on PET/CT may be useful for the detection of myocardial inflammation in patients with Chagas cardiomyopathy, and 68Ga-DOTATOC uptake may be associated with the presence of malignant arrhythmia, with potential therapeutic implications.

Vascular adhesion protein-1-targeted PET imaging in autoimmune myocarditis

BACKGROUND

Vascular adhesion protein-1 (VAP-1) is an adhesion molecule and primary amine oxidase, and Gallium-68-labeled 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetra-acetic acid conjugated sialic acid-binding immunoglobulin-like lectin 9 motif containing peptide ([68Ga]Ga-DOTA-Siglec-9) is a positron emission tomography (PET) tracer targeting VAP-1. We evaluated the feasibility of PET imaging with [68Ga]Ga-DOTA-Siglec-9 for the detection of myocardial lesions in rats with autoimmune myocarditis.

METHODS

Rats (n = 9) were immunized twice with porcine cardiac myosin in complete Freund's adjuvant. Control rats (n = 6) were injected with Freund's adjuvant alone. On day 21, in vivo PET/computed tomography (CT) imaging with [68Ga]Ga-DOTA-Siglec-9 was performed, followed by ex vivo autoradiography, histology, and immunohistochemistry of tissue sections. In addition, myocardial samples from three patients with cardiac sarcoidosis were studied.

RESULTS

[68Ga]Ga-DOTA-Siglec-9 PET/CT images of immunized rats showed higher uptake in myocardial lesions than in myocardium outside lesions (SUVmean, 0.5 ± 0.1 vs 0.3 ± 0.1; P = .003) or control rats (SUVmean, 0.2 ± 0.03; P < .0001), which was confirmed by ex vivo autoradiography of tissue sections. Immunohistochemistry showed VAP-1-positive staining in lesions of rats with myocarditis and in patients with cardiac sarcoidosis.

CONCLUSION

VAP-1-targeted [68Ga]Ga-DOTA-Siglec-9 PET is a potential novel technique for the detection of myocardial lesions.

Hybrid PET/MR in Cardiac Imaging

In the last few years, technological advances in MR imaging, PET detectors, and attenuation correction algorithms have allowed the creation of truly integrated PET/MR imaging systems, for both clinical and research applications. These machines allow a comprehensive investigation of cardiovascular diseases, by offering a wide variety of detailed anatomical and functional data in combination. Despite significant pathophysiologic mechanisms being clarified by this new data, its clinical relevance and prognostic significance have not been demonstrated yet.

Utility of 68Ga-DOTANOC PET/CT in therapeutic monitoring of cardiac sarcoidosis

Cardiac sarcoidosis usually occurs as a manifestation of systemic sarcoidosis, even though isolated cardiac involvement is not uncommon. The usefulness of 68Ga-DOTANOC PET/CT in the diagnosis of CS has been previously documented in the literature. We present a case of cardiac sarcoidosis, where 68Ga-DOTANOC PET/CT was used for monitoring response to therapy.

Phenotyping heart failure by nuclear imaging of myocardial perfusion, metabolism, and molecular targets

Nuclear imaging techniques can detect and quantify pathophysiological processes underlying heart failure, complementing evaluation of cardiac structure and function with other imaging modalities. Combined imaging of myocardial perfusion and metabolism can identify left ventricle dysfunction caused by myocardial ischaemia that may be reversible after revascularization in the presence of viable myocardium. High sensitivity of nuclear imaging to detect targeted tracers has enabled assessment of various cellular and subcellular mechanisms of heart failure. Nuclear imaging of active inflammation and amyloid deposition is incorporated into clinical management algorithms of cardiac sarcoidosis and amyloidosis. Innervation imaging has well-documented prognostic value with respect to heart failure progression and arrhythmias. Emerging tracers specific for inflammation and myocardial fibrotic activity are in earlier stages of development but have demonstrated potential value in early characterization of the response to myocardial injury and prediction of adverse left ventricular remodelling. Early detection of disease activity is a key for transition from broad medical treatment of clinically overt heart failure towards a personalized approach aimed at supporting repair and preventing progressive failure. This review outlines the current status of nuclear imaging in phenotyping heart failure and combines it with discussion on novel developments.

Semiquantitative evaluation of 68Ga-DOTANOC uptake in the normal myocardium: establishment of reference values

BACKGROUND

To ascertain presence of physiological uptake and derive standardized uptake values (SUV) of 68Ga-DOTANOC in normal myocardium and establish reference values.

METHODS AND RESULTS

Dedicated cardiac 68Ga-DOTANOC PET/CT studies of patients referred for evaluation of cardiac sarcoidosis (CS) or myocarditis and found to be normal on visual assessment and on cardiac MRI were analyzed semiquantitatively. The studies were acquired 45-60 minutes after intravenous injection of 111-185 MBq of 68Ga-DOTANOC. Myocardial SUVmax normalized to lean body mass (SUVmax_lbm) values for septum, anterior wall, proximal lateral wall, distal lateral wall, inferior wall, and apical region were 1.12 ± .39, 1.09 ± .42, 1.26 ± .49, 1.16 ± .40, 1.23 ± .39, and 1.05 ± .40, respectively. Myocardial SUVmax_lbm-to-blood pool SUVmean_lbm ratios were calculated for each region and 95th percentile values of these ratios were considered the upper limit of normal. 95th percentile values of myocardial SUVmax_lbm-to-blood pool SUVmean_lbm ratio for the corresponding regions were 1.70, 1.70, 2.00 1.95, 2.05, and 1.70, respectively.

CONCLUSION

There can be physiological uptake of 68Ga-DOTANOC in normal myocardium and the reference values of semiquantitative parameters established in this study may be employed as a corroborative tool for visual assessment in patients undergoing 68Ga-DOTANOC PET/CT for suspected CS or myocarditis.

Cardiac sarcoidosis: a comprehensive review of risk factors, pathogenesis, diagnosis, clinical manifestations, and treatment strategies

Cardiac Sarcoidosis (CS) is a deadly consequence of systemic sarcoidosis that inflames all three layers of the heart, especially the myocardium-clinical signs of CS range from asymptomatic disease to abrupt cardiac death. CS generally remains undiagnosed secondary to a lack of definitive diagnostic criteria, a high percentage of false negative results on endomyocardial biopsy, and ill-defining clinical manifestations of the disease. Consequently, there is a lack of evidence-based recommendations for CS, and the present diagnostic and therapeutic management depend on expert opinion. The aetiology, risk factors, clinical symptoms, diagnosis, and therapy of CS will be covered in this review. A particular emphasis will be placed on enhanced cardiovascular imaging and early identification of CS. We review the emerging evidence regarding the use of Electrocardiograms (ECGs), Magnetic Resonance Imaging (MRI), and Positron Emission Tomography (PET) imaging of the heart to identify and quantify the extent of myocardial inflammation, as well as to guide the use of immunotherapy and other treatment regimens, such as ablation therapy, device therapy, and heart transplantation, to improve patient outcomes.

Molecular Imaging of Innate Immunity and Immunotherapy

The innate immune system plays a key role as the first line of defense in various human diseases including cancer, cardiovascular and inflammatory diseases. In contrast to tissue biopsies and blood biopsies, in vivo imaging of the innate immune system can provide whole body measurements of immune cell location and function and changes in response to disease progression and therapy. Rationally developed molecular imaging strategies can be used in evaluating the status and spatio-temporal distributions of the innate immune cells in near real-time, mapping the biodistribution of novel innate immunotherapies, monitoring their efficacy and potential toxicities, and eventually for stratifying patients that are likely to benefit from these immunotherapies. In this review, we will highlight the current state-of-the-art in noninvasive imaging techniques for preclinical imaging of the innate immune system particularly focusing on cell trafficking, biodistribution, as well as pharmacokinetics and dynamics of promising immunotherapies in cancer and other diseases; discuss the unmet needs and current challenges in integrating imaging modalities and immunology and suggest potential solutions to overcome these barriers.

FDG PET/CT Imaging of Sarcoidosis

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. The diagnostic can be made by histological identification of non-caseous granuloma or by a combination of clinical criteria. Active inflammatory granuloma can lead to fibrotic damage. Although 50% of cases resolve spontaneously, systemic treatments are often necessary to decrease symptoms and avoid permanent organ dysfunction, notably in cardiac sarcoidosis. The course of the disease can be punctuated by exacerbations and relapses and the prognostic depends mainly on affected sites and patient management. FDG-PET/CT along with newer FDG-PET/MR have emerged as key imaging modalities in sarcoidosis, namely for certain diagnostic purposes, staging and biopsy guiding. By identifying with a high sensitivity inflammatory active granuloma, FDG hybrid imaging is a main prognostic tool and therapeutic ally in sarcoidosis. This review aims to highlight the actual critical roles of hybrid PET imaging in sarcoidosis and display a brief perspective for the future which appears to include other radiotracers and artificial intelligence applications.

Cardiovascular positron emission tomography: established and emerging role in cardiovascular diseases

Cardiac positron emission tomography (PET) imaging has established themselves firmly as excellent and reliable functional imaging modalities in assessment of the spectrum of coronary artery disease. With the explosion of technology advances and the dream of flow quantification now a reality, the value of PET is now well realized. Cardiac PET has proved itself as precise imaging modality that provides functional imaging of the heart in addition to anatomical imaging. It has established itself as one of the best available techniques for evaluation of myocardial viability. Hybrid PET/computed tomography provides simultaneous integration of coronary anatomy and function with myocardial perfusion and metabolism, thereby improving characterization of the dysfunctional area and chronic coronary artery disease. The availability of quantitative myocardial blood flow evaluation with PET provides additional prognostic information and increases diagnostic accuracy in the management of patients with coronary artery disease. Hybrid imaging seems to hold immense potential in optimizing management of cardiovascular diseases and furthering clinical research.

Clinical Utilization of Multimodality Imaging for Myocarditis and Cardiac Sarcoidosis

Myocarditis is defined as inflammation of the myocardium according to clinical, histological, biochemical, immunohistochemical, or imaging findings. Inflammation can be categorized histologically by cell type or pattern, and many causes have been implicated, including infectious, most commonly viral, systemic autoimmune diseases, vaccine-associated processes, environmental factors, toxins, and hypersensitivity to drugs. Sarcoid myocarditis is increasingly recognized as an important cause of cardiomyopathy and has important diagnostic, prognostic, and therapeutic implications in patients with systemic sarcoidosis. The clinical presentation of myocarditis may include an asymptomatic, subacute, acute, fulminant, or chronic course and may have focal or diffuse involvement of the myocardium depending on the cause and time point of the disease. For most causes of myocarditis except sarcoidosis, myocardial biopsy is the gold standard but is limited due to risk, cost, availability, and variable sensitivity. Diagnostic criteria have been established for both myocarditis and cardiac sarcoidosis and include clinical and imaging findings particularly the use of cardiac magnetic resonance and positron emission tomography. Beyond diagnosis, imaging findings may also provide prognostic value. This case-based review focuses on the current state of multimodality imaging for the diagnosis and management of myocarditis and cardiac sarcoidosis, highlighting multimodality imaging approaches with practical clinical vignettes, with a discussion of knowledge gaps and future directions.

Novel Radiotracers for Molecular Imaging of Myocardial Inflammation: an Update Focused on Clinical Translation of Non-18F-FDG Radiotracers

Purpose of Review

The purpose of this paper is to provide a focused update on recent advances in non-18F-FDG radiotracers for myocardial inflammatory diseases, with a focus on cardiac sarcoidosis and myocarditis.

Recent Findings

Novel radiotracers targeting molecular features of inflammation have the potential to visualize underlying molecular mechanisms key to the pathogenesis of inflammatory cardiomyopathies such as sarcoidosis and myocarditis. These radiotracers may provide unique opportunities for improved mechanistic insight, higher specificity, and better quantification of disease activity, as well as potential for guidance and monitoring of immunomodulatory therapies.

Summary

Novel radiotracers provide unique possibilities in diagnosis, prognostic performance, and therapy guidance for cardiac sarcoidosis and myocarditis.

Best Practices for the Catheter Ablation of Ventricular Arrhythmias

Techniques for catheter ablation have evolved to effectively treat a range of ventricular arrhythmias. Pre-operative electrocardiographic and cardiac imaging data are very useful in understanding the arrhythmogenic substrate and can guide mapping and ablation. In this review, we focus on best practices for catheter ablation, with emphasis on tailoring ablation strategies, based on the presence or absence of structural heart disease, underlying clinical status, and hemodynamic stability of the ventricular arrhythmia. We discuss steps to make ablation safe and prevent complications, and techniques to improve the efficacy of ablation, including optimal use of electroanatomical mapping algorithms, energy delivery, intracardiac echocardiography, and selective use of mechanical circulatory support.

Potential novel imaging targets of inflammation in cardiac sarcoidosis

Cardiac sarcoidosis (CS) is an inflammatory disease with high morbidity and mortality, with a pathognomonic feature of non-caseating granulomatous inflammation. While 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a well-established modality to image inflammation and diagnose CS, there are limitations to its specificity and reproducibility. Imaging focused on the molecular processes of inflammation including the receptors and cellular microenvironments present in sarcoid granulomas provides opportunities to improve upon FDG-PET imaging for CS. This review will highlight the current limitations of FDG-PET imaging for CS while discussing emerging new nuclear imaging molecular targets for the imaging of cardiac sarcoidosis.

Utility of PET/Computed Tomography in Infection and Inflammation Imaging

The role of nuclear medicine for noninvasive assessment of infection and inflammation is well established. The role of nuclear medicine is limited to initial diagnosis, recurrence, and response assessment of infections and inflammations such as tuberculosis, sarcoidosis, vasculitis, osteomyelitis, immunoglobulin G4-related diseases, and coronavirus disease 2019, as the specificity is affected by false positivity due to physiologic fluorodeoxyglucose uptake in specific organ and nonspecific uptake in postoperative cases. PET with fludeoxyglucose F 18/CT is a well-established modality for diagnosis of fever of unknown origin helping in optimized management of the patient.

Diagnostic Accuracy of Cardiac MRI versus FDG PET for Cardiac Sarcoidosis: A Systematic Review and Meta-Analysis

Background There is limited consensus regarding the relative diagnostic performance of cardiac MRI and fluorodeoxyglucose (FDG) PET for cardiac sarcoidosis. Purpose To perform a systematic review and meta-analysis to compare the diagnostic accuracy of cardiac MRI and FDG PET for cardiac sarcoidosis. Materials and Methods Medline, Ovid Epub, Cochrane Central Register of Controlled Trials, Embase, Emcare, and Scopus were searched from inception until January 2022. Inclusion criteria included studies that evaluated the diagnostic accuracy of cardiac MRI or FDG PET for cardiac sarcoidosis in adults. Data were independently extracted by two investigators. Summary accuracy metrics were obtained by using bivariate random-effects meta-analysis. Meta-regression was used to assess the effect of different covariates. Risk of bias was assessed using the Quality Assessment Tool for Diagnostic Accuracy Studies-2 tool. The study protocol was registered a priori in the International Prospective Register of Systematic Reviews (Prospero protocol CRD42021214776). Results Thirty-three studies were included (1997 patients, 687 with cardiac sarcoidosis); 17 studies evaluated cardiac MRI (1031 patients) and 26 evaluated FDG PET (1363 patients). Six studies directly compared cardiac MRI and PET in the same patients (303 patients). Cardiac MRI had higher sensitivity than FDG PET (95% vs 84%; P = .002), with no difference in specificity (85% vs 82%; P = .85). In a sensitivity analysis restricted to studies with direct comparison, point estimates were similar to those from the overall analysis: cardiac MRI and FDG PET had sensitivities of 92% and 81% and specificities of 72% and 82%, respectively. Covariate analysis demonstrated that sensitivity for FDG PET was highest with quantitative versus qualitative evaluation (93% vs 76%; P = .01), whereas sensitivity for MRI was highest with inclusion of T2 imaging (99% vs 88%; P = .001). Thirty studies were at risk of bias. Conclusion Cardiac MRI had higher sensitivity than fluorodeoxyglucose PET for diagnosis of cardiac sarcoidosis but similar specificity. Limitations, including risk of bias and few studies with direct comparison, necessitate additional study. © RSNA, 2022 Online supplemental material is available for this article.

Clinical Applications of Somatostatin Receptor (Agonist) PET Tracers beyond Neuroendocrine Tumors

Somatostatin receptor (SSTR) agonist tracers used in nuclear medicine scans are classically used for neuroendocrine tumor diagnosis and staging. SSTR are however, expressed more widely in a variety of cells as seen in the distribution of physiological tracer uptake during whole body scans. This provides opportunities for using these tracers for applications other than NETs and meningiomas. In this qualitative systematic review, novel diagnostics in SSTR-PET imaging are reviewed. A total of 70 studies comprised of 543 patients were qualitatively reviewed. Sarcoidosis, atherosclerosis and phosphaturic mesenchymal tumors represent the most studied applications currently with promising results. Other applications remain in progress where there are many case reports but a relative dearth of cohort studies. [¹⁸F]FDG PET provides the main comparative method in many cases but represents a well-established general PET technique that may be difficult to replace, without prospective clinical studies.

Current State and Future Directions of Multimodality Imaging in Cardiac Sarcoidosis

Cardiac sarcoidosis (CS) is an increasingly recognized cause of heart failure and arrhythmia. Historically challenging to identify, particularly in the absence of extracardiac sarcoidosis, diagnosis of CS has improved with advancements in cardiac imaging. Recognition as well as management may require interpretation of multiple imaging modalities. Echocardiography may serve as an initial screening study for cardiac involvement in patients with systemic sarcoidosis. Cardiac magnetic resonance imaging (CMR) provides information on diagnosis as well as risk stratification, particularly for ventricular arrhythmia in the setting of late gadolinium enhancement. More recently, ¹⁸F-fluorodeoxyglucose position emission tomography (FDG-PET) has assumed a valuable role in the diagnosis and longitudinal management of patients with CS, allowing for the assessment of response to treatment. Hybrid FDG-PET/CT may also be used in the evaluation of extracardiac inflammation, permitting the identification of biopsy sites for diagnostic confirmation. Herein we examine the approach to diagnosis and management of CS using multimodality imaging via a case-based review.

Quantitative Assessment of Cardiac Hypermetabolism and Perfusion for Diagnosis of Cardiac Sarcoidosis

BACKGROUND

Quantitative assessment of cardiac hypermetabolism from 18Flourodeoxy glucose (FDG) positron emission tomography (PET) may improve diagnosis of cardiac sarcoidosis (CS). We assessed different approaches for quantification of cardiac hypermetabolism and perfusion in patients with suspected CS.

METHODS AND RESULTS

Consecutive patients undergoing 18FDG PET assessment for possible CS between January 2014 and March 2019 were included. Cardiac hypermetabolism was quantified using maximal standardized uptake value (SUVMAX), cardiometabolic activity (CMA) and volume of inflammation, using relative thresholds (1.3× and 1.5× left ventricular blood pool [LVBP] activity), and absolute thresholds (SUVMAX > 2.7 and 4.1). Diagnosis of CS was established using the Japanese Ministry of Health and Wellness criteria. In total, 69 patients were studied, with definite or possible CS in 29(42.0%) patients. CMA above 1.5× LVBP SUVMAX had the highest area under the receiver operating characteristic curve (AUC 0.92). Quantitative parameters using relative thresholds had higher AUC compared to absolute thresholds (p < 0.01). Interobserver variability was low for CMA, with excellent agreement regarding absence of activity (Kappa 0.970).

CONCLUSIONS

Quantitation with scan-specific thresholds has superior diagnostic accuracy compared to absolute thresholds. Based on the potential clinical benefit, programs should consider quantification of cardiac hypermetabolism when interpreting 18F-FDG PET studies for CS.

Evaluation of [68Ga]Ga-NODAGA-RGD for PET Imaging of Rat Autoimmune Myocarditis

The ⁶⁸Gallium-labeled 1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid conjugated radiolabelled arginine-glycine-aspartic acid peptide ([⁶⁸Ga]Ga-NODAGA-RGD) is a positron emission tomography (PET) tracer binding to cell surface receptor α_vβ₃ integrin that is upregulated during angiogenesis and inflammation. We studied whether α_vβ₃ targeting PET imaging can detect myocardial inflammation in a rat model of autoimmune myocarditis. To induce myocarditis, rats (n = 8) were immunized with porcine cardiac myosin in complete Freund's adjuvant on days 0 and 7. Control rats (n = 8) received Freund's adjuvant alone. On day 21, in vivo PET/CT imaging with [⁶⁸Ga]Ga-NODAGA-RGD followed by ex vivo autoradiography and immunohistochemistry were carried out. Inflammatory lesions were detected histologically in the myocardium of 7 out of 8 immunized rats. In vivo PET images showed higher [⁶⁸Ga]Ga-NODAGA-RGD accumulation in the myocardium of rats with inflammation than the non-inflamed myocardium of control rats (SUV_mean 0.4 ± 0.1 vs. 0.1 ± 0.02; P = 0.00006). Ex vivo autoradiography and histology confirmed that [⁶⁸Ga]Ga-NODAGA-RGD uptake co-localized with inflammatory lesions containing α_vβ₃ integrin-positive capillary-like structures. A non-specific [⁶⁸Ga]Ga-DOTA-(RGE)₂ tracer showed 76% lower uptake than [⁶⁸Ga]Ga-NODAGA-RGD in the inflamed myocardium. Our results indicate that α_vβ₃ integrin-targeting [⁶⁸Ga]Ga-NODAGA-RGD is a potential PET tracer for the specific detection of active inflammatory lesions in autoimmune myocarditis.

PET Imaging in Cardiac Sarcoidosis: A Narrative Review with Focus on Novel PET Tracers

Sarcoidosis is a multi-system inflammatory disease characterized by the development of inflammation and noncaseating granulomas that can involve nearly every organ system, with a predilection for the pulmonary system. Cardiac involvement of sarcoidosis (CS) occurs in up to 70% of cases, and accounts for a significant share of sarcoid-related mortality. The clinical presentation of CS can range from absence of symptoms to conduction abnormalities, heart failure, arrhythmias, valvular disease, and sudden cardiac death. Given the significant morbidity and mortality associated with CS, timely diagnosis is important. Traditional imaging modalities and histologic evaluation by endomyocardial biopsy often provide a low diagnostic yield. Cardiac positron emission tomography (PET) has emerged as a leading advanced imaging modality for the diagnosis and management of CS. This review article will summarize several aspects of the current use of PET in CS, including indications for use, patient preparation, image acquisition and interpretation, diagnostic and prognostic performance, and evaluation of treatment response. Additionally, this review will discuss novel PET radiotracers currently under study or of potential interest in CS.

18F-FMISO PET/CT detects hypoxic lesions of cardiac and extra-cardiac involvement in patients with sarcoidosis

BACKGROUND

18F-fluoromisonidazole (FMISO) is a hypoxia positron emission tomography (PET) tracer. Here, we evaluated cardiac and extra-cardiac sarcoidosis using both FMISO and 18F-fluorodeoxyglucose (FDG) PET/CT in a prospective cohort of patients with sarcoidosis.

METHODS

Ten consecutive sarcoidosis patients with suspected cardiac involvement were prospectively enrolled. Each patient fasted overnight (for ≥ 18 hours) preceded by a low-carbohydrate diet before FDG PET/CT but not given special dietary instructions before the FMISO PET/CT scan. We visually and semiquantitatively assessed the uptakes of FMISO and FDG using the maximal standardized uptake value (SUVmax). The metabolic volume (MV) of FDG was calculated as the volume within the boundary determined by the threshold (mean SUV of blood pool × 1.5).

RESULTS

Nine patients showed focal FDG uptake in the myocardium and were diagnosed with cardiac sarcoidosis. Among the patients with extra-cardiac lesions, FDG uptake was seen in 8 lymph nodes and 3 lung lesions. FMISO uptake was seen in the 7 cardiac (77.8%) and 6 extra-cardiac (54.5%) lesions. None of the patients showed physiological FMISO uptake in the myocardium. The SUVmax values of the lesions with FMISO uptake were higher than those of the lesions without FMISO uptake in both the cardiac (SUVmax: 9.9, IQR: 8.4-10.0 vs 7.3, IQR: 6.3-8.2) and non-cardiac lesions (SUVmax: 17.6, IQR: 14.5-19.3 vs 6.1, IQR: 5.9-6.2; P = 0.006). The MV values of the lesions with FMISO uptake were significantly higher than those of the lesions without FMISO uptake (111.3, IQR: 78.3-135.7 vs 6.4, IQR: 1.9-23.3; P = 0.0009).

CONCLUSIONS

FMISO showed no physiological myocardial uptake and did not require special preparation. FMISO PET has the potential to detect hypoxic lesions in patients with sarcoidosis.

Positron Emission Tomography Techniques to Measure Active Inflammation, Fibrosis and Angiogenesis: Potential for Non-invasive Imaging of Hypertensive Heart Failure

Heart failure, which is responsible for a high number of deaths worldwide, can develop due to chronic hypertension. Heart failure can involve and progress through several different pathways, including: fibrosis, inflammation, and angiogenesis. Early and specific detection of changes in the myocardium during the transition to heart failure can be made via the use of molecular imaging techniques, including positron emission tomography (PET). Traditional cardiovascular PET techniques, such as myocardial perfusion imaging and sympathetic innervation imaging, have been established at the clinical level but are often lacking in pathway and target specificity that is important for assessment of heart failure. Therefore, there is a need to identify new PET imaging markers of inflammation, fibrosis and angiogenesis that could aid diagnosis, staging and treatment of hypertensive heart failure. This review will provide an overview of key mechanisms underlying hypertensive heart failure and will present the latest developments in PET probes for detection of cardiovascular inflammation, fibrosis and angiogenesis. Currently, selective PET probes for detection of angiogenesis remain elusive but promising PET probes for specific targeting of inflammation and fibrosis are rapidly progressing into clinical use.

Limitations and Pitfalls of FDG-PET/CT in Infection and Inflammation

White blood cells activated by either a pathogen or as part of a systemic inflammatory disease are characterized by high energy consumption and are therefore taking up the glucose analogue PET tracer FDG avidly. It is therefore not surprising that a steadily growing body of research and clinical reports now supports the use of FDG PET/CT to diagnose a wide range of patients with non-oncological diseases. However, using FDG PET/CT in patients with infectious or inflammatory diseases has some limitations and potential pitfalls that are not necessarily as pronounced in oncology FDG PET/CT. Some of these limitations are of a general nature and related to the laborious acquisition of PET images in patients that are often acutely ill, whereas others are more disease-specific and related to the particular metabolism in some of the organs most commonly affected by infections or inflammatory disease. Both inflammatory and infectious diseases are characterized by a more diffuse and less pathognomonic pattern of FDG uptake than oncology FDG PET/CT and the affected organs also typically have some physiological FDG uptake. In addition, patients referred to PET/CT with suspected infection or inflammation are rarely treatment naïve and may have received varying doses of antibiotics, corticosteroids or other immune-modulating drugs at the time of their examination. Combined, this results in a higher rate of false positive FDG findings and also in some cases a lower sensitivity to detect active disease. In this review, we therefore discuss the limitations and pitfalls of FDG PET/CT to diagnose infections and inflammation taking these issues into consideration. Our review encompasses the most commonly encountered inflammatory and infectious diseases in head and neck, in the cardiovascular system, in the abdominal organs and in the musculoskeletal system. Finally, new developments in the field of PET/CT that may help overcome some of these limitations are briefly highlighted.

Emerging Preclinical and Clinical Applications of Theranostics for Nononcological Disorders

Studies in nuclear medicine have shed light on molecular imaging and therapeutic approaches for oncological and nononcological conditions. Using the same radiopharmaceuticals for diagnosis and therapeutics of malignancies, the theranostics approach, has improved clinical management of patients. Theranostic approaches for nononcological conditions are recognized as emerging topics of research. This review focuses on preclinical and clinical studies of nononcological disorders that include theranostic strategies. Theranostic approaches are demonstrated as possible in the clinical management of infections and inflammations. There is an emerging need for randomized trials to specify the factors affecting validity and efficacy of theranostic approaches in nononcological diseases.

Procedural recommendations of cardiac PET/CT imaging: standardization in inflammatory-, infective-, infiltrative-, and innervation- (4Is) related cardiovascular diseases: a joint collaboration of the EACVI and the EANM: summary

With this summarized document we share the standard for positron emission tomography (PET)/(diagnostic)computed tomography (CT) imaging procedures in cardiovascular diseases that are inflammatory, infective, infiltrative, or associated with dysfunctional innervation (4Is) as recently published in the European Journal of Nuclear Medicine and Molecular Imaging. This standard should be applied in clinical practice and integrated in clinical (multicentre) trials for optimal standardization of the procedurals and interpretations. A major focus is put on procedures using [¹⁸F]-2-fluoro-2-deoxyglucose ([¹⁸F]FDG), but 4Is PET radiopharmaceuticals beyond [¹⁸F]FDG are also described in this summarized document. Whilst these novel tracers are currently mainly applied in early clinical trials, some multicentre trials are underway and we foresee in the near future their use in clinical care and inclusion in the clinical guidelines. Diagnosis and management of 4Is related cardiovascular diseases are generally complex and often require a multidisciplinary approach by a team of experts. The new standards described herein should be applied when using PET/CT and PET/magnetic resonance, within a multimodality imaging framework both in clinical practice and in clinical trials for 4Is cardiovascular indications.

Comparison of 68Ga-DOTANOC PET/CT with cardiac MRI in patients with clinical suspicion of cardiac sarcoidosis

BACKGROUND

⁶⁸Ga-DOTA-NaI-octreotide (DOTANOC) is a promising new alternative to ¹⁸F-fluorodeoxyglucose (FDG) for imaging inflammation in cardiac sarcoidosis. The aim of the study was to compare ⁶⁸Ga-DOTANOC positron emission tomography/computed tomography (PET/CT) with cardiac magnetic resonance imaging (CMR) in patients with clinical suspicion of cardiac sarcoidosis.

METHODS AND RESULTS

Patients with extracardiac sarcoidosis and clinical suspicion of cardiac involvement underwent ⁶⁸Ga-DOTANOC cardiac PET/CT, myocardial perfusion single photon emission computed tomography (MPS) and CMR (T2-weighted and delayed gadolinium-enhanced T1-weighted images). The patients were screened using revised criteria of Japanese circulation society. Presence of perfusion defects on MPS, abnormal myocardial uptake on ⁶⁸Ga-DOTANOC PET/CT and characteristic pattern of late gadolinium enhancement (LGE) with or without T2 hyperintensity on CMR was considered positive.

RESULTS

Seventeen patients (13 male and 4 female) were included in the study. Out of the 17 patients, both CMR and PET were positive in 11 and both were negative in 2. In the remaining 4 patients, CMR was positive but PET was normal. Thus, PET and CMR were concordant in 13 (76.5%) patients and discordant in 4 (23.5%). Intermodality agreement was fair (Cohen's kappa = 0.39).

CONCLUSION

LGE on CMR is superior to ⁶⁸Ga-DOTANOC PET/CT for detecting cardiac involvement in sarcoidosis and there is fair concordance between the two. However, since LGE does not specifically differentiate between inflammation and fibrosis, ⁶⁸Ga-DOTANOC PET/CT may be better than CMR in identifying patients with active inflammation, since it directly targets inflammatory cells and can have a complementary role to CMR.

Feasibility of somatostatin receptor-targeted imaging for detection of myocardial inflammation: A pilot study

BACKGROUND

Gallium-68 Dotatate binds preferentially to somatostatin receptor (sstr) subtype-2 (sstr-2) on inflammatory cells. We aimed at investigating the potential clinical use of sstr-targeted imaging for the detection of myocardial inflammation.

METHODS

Thirteen patients, with suspected cardiac sarcoidosis (CS) based on clinical history and myocardial uptake on recent fluorine-18 fluorodeoxyglucose (FDG) PET, were enrolled to undergo Dotatate PET after FDG-PET (median time 37 days [IQR 25-55]). Additionally, we investigated ex-vivo the immunohistochemistry expression of sstr-2 in 3 explanted sarcoid hearts.

RESULTS

All FDG scans showed cardiac uptake (focal/multifocal = 6, focal on diffuse/heterogeneous = 7), and 46% (n = 6) extra-cardiac uptake (mediastinal/hilar). In comparison, Dotatate scans showed definite abnormal cardiac uptake (focal/multifocal) in 4 patients, probably abnormal (heterogenous/patchy) in 3, and negative uptake in 6 cases. Similarly, 6 patients had increased mediastinal/hilar Dotatate uptake. Overall concordance of FDG and Dotatate uptake was 54% in the heart and 100% for thoracic nodal activity. Quantitatively, FDG maximum standardized uptake value was 5.0 times [3.8-7.1] higher in the heart, but only 2.25 times [1.7-3.0; P = .019] higher in thoracic nodes relative to Dotatate. Ex-vivo, sstr-2 immunostaining was weakly seen within well-formed granulomas in all 3 examined sarcoid heart specimens with no significant staining of background myocardium or normal myocardium.

CONCLUSION

Our preliminary data suggest that, compared to FDG imaging, somatostatin receptor-targeted imaging may be less sensitive for the detection of myocardial inflammation, but comparable for detecting extra-cardiac inflammation.

Machine learning and network medicine: a novel approach for precision medicine and personalized therapy in cardiomyopathies

The early identification of pathogenic mechanisms is essential to predict the incidence and progression of cardiomyopathies and to plan appropriate preventive interventions. Noninvasive cardiac imaging such as cardiac computed tomography, cardiac magnetic resonance, and nuclear imaging plays an important role in diagnosis and management of cardiomyopathies and provides useful prognostic information. Most molecular factors exert their functions by interacting with other cellular components, thus many diseases reflect perturbations of intracellular networks. Indeed, complex diseases and traits such as cardiomyopathies are caused by perturbations of biological networks. The network medicine approach, by integrating systems biology, aims to identify pathological interacting genes and proteins, revolutionizing the way to know cardiomyopathies and shifting the understanding of their pathogenic phenomena from a reductionist to a holistic approach. In addition, artificial intelligence tools, applied to morphological and functional imaging, could allow imaging scans to be automatically analyzed to extract new parameters and features for cardiomyopathy evaluation. The aim of this review is to discuss the tools of network medicine in cardiomyopathies that could reveal new candidate genes and artificial intelligence imaging-based features with the aim to translate into clinical practice as diagnostic, prognostic, and predictive biomarkers and shed new light on the clinical setting of cardiomyopathies. The integration and elaboration of clinical habits, molecular big data, and imaging into machine learning models could provide better disease phenotyping, outcome prediction, and novel drug targets, thus opening a new scenario for the implementation of precision medicine for cardiomyopathies.

The Role of Multimodality Imaging in Cardiac Sarcoidosis

The etiology and the progression of sarcoidosis remain unknown. However, cardiac sarcoidosis (CS) is significantly associated with a poor prognosis due to the associated congestive heart failure, arrhythmias (such as an advanced atrioventricular block), and ventricular tachyarrhythmia. Novel imaging modalities are now available to detect CS lesions secondary to active inflammation, granuloma formation, and fibrotic changes. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and cardiac magnetic resonance imaging (CMR) play essential roles in diagnosing and monitoring patients with confirmed or suspected CS. The following focused review will highlight the emerging role of non-invasive cardiac imaging techniques, including FDG PET/CT and CMR.

Nuclear medicine and molecular imaging in clinical practice: yesterday, today and tomorrow

Over the past 40 years, nuclear medicine has grown to be the largest non-invasive diagnostic and therapeutic industry in the world, playing a pivotal role in various fields and disciplines of clinical practice and contributing to improved quality of life and patient prognosis. Over the first 20 years of the XXI century, the number of radionuclide procedures in the world has increased significantly, primarily due to innovations in radiopharmaceuticals, continuous improvement of the technical properties of equipment and the expansion of the boundaries of multimodal imaging. The review examines the historical and current trends in the development of nuclear medicine in the world and in Russia, including those related to radionuclide diagnostics, therapy and theranostics.

Imaging Inflammation with Positron Emission Tomography

The impact of inflammation on the outcome of many medical conditions such as cardiovascular diseases, neurological disorders, infections, cancer, and autoimmune diseases has been widely acknowledged. However, in contrast to neurological, oncologic, and cardiovascular disorders, imaging plays a minor role in research and management of inflammation. Imaging can provide insights into individual and temporospatial biology and grade of inflammation which can be of diagnostic, therapeutic, and prognostic value. There is therefore an urgent need to evaluate and understand current approaches and potential applications for imaging of inflammation. This review discusses radiotracers for positron emission tomography (PET) that have been used to image inflammation in cardiovascular diseases and other inflammatory conditions with a special emphasis on radiotracers that have already been successfully applied in clinical settings.

Non-18F-FDG/18F-NaF Radiotracers Proposed for the Diagnosis and Management of Diseases of the Heart and Vasculature

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and ¹⁸F-sodium fluoride (¹⁸F-NaF) are front-runners in PET. However, these tracers have limitations in the imaging of diseases in the heart. A multitude of other radiotracers have been identified as potentially useful PET agents in the identification of cardiovascular disease. This critical review examines recent studies with the use of non-¹⁸F-FDG/¹⁸F-NaF radiotracers in the identification and surveillance of cardiovascular diseases. We highlight the need for further investigation into alternative PET radiotracers to demonstrate their clinical value in the management of these pathologies.

Diagnostic performance of F-18 FDG PET for detection of cardiac sarcoidosis; A systematic review and meta-analysis

OBJECTIVE

The purpose of the current study was to investigate the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for diagnosis of cardiac sarcoidosis (CS) through a systematic review and meta-analysis.

METHODS

The PubMed and EMBASE database, from the earliest available date of indexing through 31 March 31, 2018, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT for CS. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic (SROC) curves.

RESULTS

Across 17 studies (891 patients), the pooled sensitivity was 0.84 [95% confidence interval (95% CI) 0.71-0.91] with heterogeneity (I2 = 77.5) and a pooled specificity of 0.83 (95% CI 0.74-0.89) with heterogeneity (I2 = 80.0). Likelihood ratio (LR) syntheses gave an overall LR+ of 4.9 (95% CI 3.3-7.3) and LR- of 0.2 (95% CI 0.11-0.35). The pooled diagnostic odds ratio was 27 (95% CI 14-55). Hierarchical SROC curve indicates that the area under the curve was 0.90 (95% CI 0.87-0.92). Meta-regression showed that combined myocardial perfusion imaging was the source of heterogeneity.

CONCLUSION

The current meta-analysis showed the moderate sensitivity and specificity of F-18 FDG PET or PET/CT for diagnosis of CS. The presence of combined myocardial perfusion imaging could improve diagnostic accuracy of F-18 FDG PET or PET/CT for diagnosis of CS. At present, the literature regarding the use of F-18 FDG PET for detection of CS remains limited; thus, further large multicenter studies would be necessary to substantiate the diagnostic accuracy of F-18 FDG PET for diagnosis of CS.

Procedural recommendations of cardiac PET/CT imaging: standardization in inflammatory-, infective-, infiltrative-, and innervation (4Is)-related cardiovascular diseases: a joint collaboration of the EACVI and the EANM

With this document, we provide a standard for PET/(diagnostic) CT imaging procedures in cardiovascular diseases that are inflammatory, infective, infiltrative, or associated with dysfunctional innervation (4Is). This standard should be applied in clinical practice and integrated in clinical (multicenter) trials for optimal procedural standardization. A major focus is put on procedures using [¹⁸F]FDG, but 4Is PET radiopharmaceuticals beyond [¹⁸F]FDG are also described in this document. Whilst these novel tracers are currently mainly applied in early clinical trials, some multicenter trials are underway and we foresee in the near future their use in clinical care and inclusion in the clinical guidelines. Finally, PET/MR applications in 4Is cardiovascular diseases are also briefly described. Diagnosis and management of 4Is-related cardiovascular diseases are generally complex and often require a multidisciplinary approach by a team of experts. The new standards described herein should be applied when using PET/CT and PET/MR, within a multimodality imaging framework both in clinical practice and in clinical trials for 4Is cardiovascular indications.

Excellent suppression of physiological myocardial FDG activity in patients with cardiac sarcoidosis

INTRODUCTION

Suppression of physiological myocardial FDG activity is vital in patients undergoing PET/CT for assessment of known or suspected cardiac sarcoidosis. This study aims to evaluate the efficacy of physiological myocardial FDG suppression following a protocol change to a 24-h high fat very low carbohydrate (HFVLC) diet and prolonged fast.

METHODS

A retrospective review of patients undergoing FDG PET/CT for the evaluation of cardiac sarcoidosis was performed. Prior to June-2018, patients were prepared with a single very high-fat low carbohydrate meal followed by a 12-18 h fast (group 1). After June-2018, a protocol change was initiated with patients prepared with a HFVLC diet for 24-h followed by a 12-18 h fast (group 2). Focal myocardial activity was classified as positive, absent activity as negative and diffuse/focal on diffuse activity as indeterminate.

RESULTS

A total of 94 FDG PET/CT scans were included with 46 scans in group 1 and 48 scans in group 2. Studies were classified as positive, negative or indeterminate in 25 (54%), 7 (15%) and 14 (30%) scans in group 1 and in 13 (27%), 33 (69%) and 2 (4%) scans in group 2, respectively. In scans classified as negative, myocardial FDG activity was less than mediastinal blood pool activity in 5/7 (71%) scans in group 1 and 33/33 (100%) scans in group 2.

CONCLUSION

Excellent myocardial FDG suppression can be achieved using a 24-h HFVLC diet and prolonged fast, resulting in a very low indeterminate scan rate in patients with known or suspected cardiac sarcoidosis.

[A review on cardiac positron emission tomography/magnetic resonance imaging in diagnosis of cardivascular diseases]

There are various examination methods for cardiovascular diseases. Non-invasive diagnosis and prognostic information acquisition are the current research hotspots of related imaging examinations. Positron emission tomography (PET)/magnetic resonance imaging (MRI) is a new advanced fusion imaging technology that combines the molecular imaging of PET with the soft tissue contrast function of MRI to achieve their complementary advantages. This article briefly introduces several major aspects of cardiac PET/MRI in the diagnosis of cardiovascular disease, including atherosclerosis, ischemic cardiomyopathy, nodular heart disease, and myocardial amyloidosis, in order to promote cardiac PET/MRI to be more widely used in precision medicine in this field.