18F-FDG PET/CT for the Assessment of Myocardial Sarcoidosis

Imaging of Cardiac Fibrosis: How Far Have We Moved From Extracellular to Cellular?

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. Myocardial fibrosis plays an important role in adverse outcomes such as heart failure and arrhythmias. As the pathological response and degree of scarring, and therefore clinical presentation varies from patient to patient, early detection of fibrosis is crucial for identifying the appropriate treatment approach and forecasting the progression of a disease along with the likelihood of disease-related mortality. Current imaging modalities provides information about either decreased function or extracellular signs of fibrosis. Targeting activated fibroblasts represents a burgeoning approach that could offer insights prior to observable functional alterations, presenting a promising focus for potential anti-fibrotic therapeutic interventions at cellular level. In this article, we provide an overview of imaging cardiac fibrosis and discuss the role of different advanced imaging modalities with the focus on novel non-invasive imaging of activated fibroblasts.

A framework for exclusion of alternative diagnoses in sarcoidosis

Sarcoidosis is a multisystem granulomatous syndrome that arises from a persistent immune response to a triggering antigen(s). There is no "gold standard" test or algorithm for the diagnosis of sarcoidosis, making the diagnosis one of exclusion. The presentation of the disease varies substantially between individuals, in both the number of organs involved, and the manifestations seen in individual organs. These qualities dictate that health care providers diagnosing sarcoidosis must consider a wide range of possible alternative diagnoses, from across a range of presentations and medical specialties (infectious, inflammatory, cardiac, neurologic). Current guideline-based diagnosis of sarcoidosis recommends fulfillment of three criteria: 1) compatible clinical presentation and/or imaging 2) demonstration of granulomatous inflammation by biopsy (when possible) and, 3) exclusion of alternative causes, but do not provide guidance on standardized strategies for exclusion of alternative diagnoses. In this review, we provide a summary of the most common differential diagnoses for sarcoidosis involvement of lung, eye, skin, central nervous system, heart, liver, and kidney. We then propose a framework for testing to exclude alternative diagnoses based on pretest probability of sarcoidosis, defined as high (typical findings with sarcoidosis involvement confirmed in another organ), moderate (typical findings in a single organ), or low (atypical/findings suggesting of an alternative diagnosis). This work highlights the need for informed and careful exclusion of alternative diagnoses in sarcoidosis.

Novel tracers to assess myocardial inflammation with radionuclide imaging

Myocardial inflammation plays a central role in the pathophysiology of various cardiac diseases. While FDG-PET is currently the primary method for molecular imaging of myocardial inflammation, its effectiveness is hindered by physiological myocardial uptake as well as its propensity for uptake by multiple disease-specific mechanisms. Novel radiotracers targeting diverse inflammatory immune cells and molecular pathways may provide unique insight through the visualization of underlying mechanisms central to the pathogenesis of inflammatory cardiac diseases, offering opportunities for increased understanding of immunocardiology. Moreover, the potentially enhanced specificity may lead to better quantification of disease activity, aiding in the guidance and monitoring of immunomodulatory therapy. This review aims to provide an update on advancements in non-FDG radiotracers for imaging myocardial inflammatory diseases, with a focus on cardiac sarcoidosis, myocarditis, and acute myocardial infarction.

Computational modeling of cardiac electrophysiology and arrhythmogenesis: toward clinical translation

The complexity of cardiac electrophysiology, involving dynamic changes in numerous components across multiple spatial (from ion channel to organ) and temporal (from milliseconds to days) scales, makes an intuitive or empirical analysis of cardiac arrhythmogenesis challenging. Multiscale mechanistic computational models of cardiac electrophysiology provide precise control over individual parameters, and their reproducibility enables a thorough assessment of arrhythmia mechanisms. This review provides a comprehensive analysis of models of cardiac electrophysiology and arrhythmias, from the single cell to the organ level, and how they can be leveraged to better understand rhythm disorders in cardiac disease and to improve heart patient care. Key issues related to model development based on experimental data are discussed, and major families of human cardiomyocyte models and their applications are highlighted. An overview of organ-level computational modeling of cardiac electrophysiology and its clinical applications in personalized arrhythmia risk assessment and patient-specific therapy of atrial and ventricular arrhythmias is provided. The advancements presented here highlight how patient-specific computational models of the heart reconstructed from patient data have achieved success in predicting risk of sudden cardiac death and guiding optimal treatments of heart rhythm disorders. Finally, an outlook toward potential future advances, including the combination of mechanistic modeling and machine learning/artificial intelligence, is provided. As the field of cardiology is embarking on a journey toward precision medicine, personalized modeling of the heart is expected to become a key technology to guide pharmaceutical therapy, deployment of devices, and surgical interventions.

Comprehensive diagnostic workup in patients with suspected heart failure and preserved ejection fraction

Diagnosis of heart failure with preserved ejection fraction (HFpEF) can be challenging and it could require different tests, some of which are affected by limited availability. Nowadays, considering that new therapies are available for HFpEF and related conditions, a prompt and correct diagnosis is relevant. However, the diagnostic role of biomarker level, imaging tools, score-based algorithms and invasive evaluation, should be based on the strengths and weaknesses of each test. The aim of this review is to help the clinician in diagnosing HFpEF, overcoming the diagnostic uncertainty and disentangling among the different underlying causes, in order to properly treat this kind of patient.

Great mimicker: definite isolated cardiac sarcoidosis masquerading as hypertrophic cardiomyopathy

A healthy man in his 50s was hospitalised after presenting with chest pain and dyspnoea. An echocardiogram revealed asymmetrical septal hypertrophy, leading to a diagnosis of hypertrophic cardiomyopathy. Due to progressive conduction abnormalities during his hospitalisation, further evaluation was performed. Cardiac MRI revealed dense late gadolinium enhancement of the septum in the area of hypertrophy. Additionally, fluorodeoxyglucose-positron emission tomography demonstrated increased uptake within the same region, suggestive of active inflammation. Subsequent endomyocardial biopsy showed non-caseating granulomatous inflammation, consistent with cardiac sarcoidosis. Treatment with prednisone and methotrexate was initiated, and an implantable cardioverter-defibrillator was placed following thorough risk stratification. This case highlights the importance of multimodality imaging and the pursuit of a tissue diagnosis in the evaluation of cardiomyopathy.

Impact of comorbid heart failure among hospitalized patients with sarcoidosis: A United States population-based cohort study

Background

There is paucity of data regarding the impact of concomitant heart failure (HF) on the in-hospital outcomes among hospitalized sarcoidosis patients. We aim to investigate the factors associated with concomitant HF and its impact on in-hospital outcomes among hospitalized sarcoidosis patients.

Methods

We utilized the 2018-2020 National Inpatient Sample (NIS) Database in conducting this study. Multivariable logistic and linear regression models were used to examine the factors associated with HF and hospital-associated outcomes among patients with sarcoidosis.

Results

A total of 36,864 hospitalized patients with sarcoidosis were identified, of which 24.78 % (n = 9135/36,864) had concomitant HF. Factors associated with concomitant HF were age (aOR 1.03; 95 % CI: 1.02-1.03, p value ≤ 0.001), black race (aOR 1.74; 95 % CI: 1.47-2.05, p value ≤ 0.001), not being female (aOR 0.79; 95 % CI: 0.69-0.91, p value ≤ 0.001), and arrhythmias (aOR 2.50; 95 % CI: 2.10-2.98, p value ≤ 0.001) specifically atrial fibrillation and ventricular tachycardia. Comorbidities associated with concomitant HF in this population were hyperlipidemia, obesity, coronary artery disease, cardiac device implantation history, and chronic kidney disease stage 1-4. Concomitant HF was not an independent predictor of in-hospital mortality or length of stay (LOS). However, age (aOR 1.04; 95 % CI, 1.03-1.06; p ≤ 0.001) and arrhythmia burden (aOR 2.08; 95 % CI, 1.47-2.95; p ≤ 0.001), specifically ventricular tachycardia and fibrillation, were independently associated with in-hospital mortality among sarcoidosis patients.

Conclusion

Traditional cardiovascular risk factors were associated with concomitant HF among hospitalized sarcoidosis patients. Moreover, concomitant HF among sarcoidosis patients was not significantly associated with in-hospital mortality or LOS.

Positron Emission Tomography in Heart Failure: From Pathophysiology to Clinical Application

Imaging modalities are increasingly being used to evaluate the underlying pathophysiology of heart failure. Positron emission tomography (PET) is a non-invasive imaging technique that uses radioactive tracers to visualize and measure biological processes in vivo. PET imaging of the heart uses different radiopharmaceuticals to provide information on myocardial metabolism, perfusion, inflammation, fibrosis, and sympathetic nervous system activity, which are all important contributors to the development and progression of heart failure. This narrative review provides an overview of the use of PET imaging in heart failure, highlighting the different PET tracers and modalities, and discussing fields of present and future clinical application.

A Case of Cardiac Sarcoidosis Masquerading As Heart Failure With Ventricular Arrhythmia

Sarcoidosis is a rare cause of cardiomyopathy that can easily be confused for acute heart failure when pulmonary manifestations are absent. We present the case of a 41-year-old female presenting with dyspnea found to have ventricular arrhythmia on arrival at the emergency department. Cardiac magnetic resonance and computed tomography of the chest with contrast were performed, confirming the systemic sarcoidosis diagnosis with cardiac involvement.

Prognostic Value of Cardiac MRI and FDG PET in Cardiac Sarcoidosis: A Systematic Review and Meta-Analysis

Background There is no consensus regarding the relative prognostic value of cardiac MRI and fluorodeoxyglucose (FDG) PET in cardiac sarcoidosis. Purpose To perform a systematic review and meta-analysis of the prognostic value of cardiac MRI and FDG PET for major adverse cardiac events (MACE) in cardiac sarcoidosis. Materials and Methods In this systematic review, MEDLINE, Ovid Epub, CENTRAL, Embase, Emcare, and Scopus were searched from inception until January 2022. Studies that evaluated the prognostic value of cardiac MRI or FDG PET in adults with cardiac sarcoidosis were included. The primary outcome of MACE was assessed as a composite including death, ventricular arrhythmia, and heart failure hospitalization. Summary metrics were obtained using random-effects meta-analysis. Meta-regression was used to assess covariates. Risk of bias was assessed using the Quality in Prognostic Studies, or QUIPS, tool. Results Thirty-seven studies were included (3489 patients with mean follow-up of 3.1 years ± 1.5 [SD]); 29 studies evaluated MRI (2931 patients) and 17 evaluated FDG PET (1243 patients). Five studies directly compared MRI and PET in the same patients (276 patients). Left ventricular late gadolinium enhancement (LGE) at MRI and FDG uptake at PET were both predictive of MACE (odds ratio [OR], 8.0 [95% CI: 4.3, 15.0] [P < .001] and 2.1 [95% CI: 1.4, 3.2] [P < .001], respectively). At meta-regression, results varied by modality (P = .006). LGE (OR, 10.4 [95% CI: 3.5, 30.5]; P < .001) was also predictive of MACE when restricted to studies with direct comparison, whereas FDG uptake (OR, 1.9 [95% CI: 0.82, 4.4]; P = .13) was not. Right ventricular LGE and FDG uptake were also associated with MACE (OR, 13.1 [95% CI: 5.2, 33] [P < .001] and 4.1 [95% CI: 1.9, 8.9] [P < .001], respectively). Thirty-two studies were at risk for bias. Conclusion Left and right ventricular late gadolinium enhancement at cardiac MRI and fluorodeoxyglucose uptake at PET were predictive of major adverse cardiac events in cardiac sarcoidosis. Limitations include few studies with direct comparison and risk of bias. Systematic review registration no. CRD42021214776 (PROSPERO) © RSNA, 2023 Supplemental material is available for this article.

FDG PET of Isolated Right Ventricular Sarcoidosis

ABSTRACT

A 62-year-old man with a history of allergic rhinitis and lightheadedness was admitted after an episode of sustained ventricular tachycardia detected by Holter monitor. A chest CT revealed peribronchial nodules, and mediastinal and hilar lymphadenopathy. The findings raised concern for sarcoidosis. MRI and FDG PET/CT were performed and revealed cardiac sarcoidosis isolated to the right ventricle only. Sarcoidosis of the right ventricle, sparing the left ventricle, is an extremely uncommon entity.

Cardiac sarcoidosis: is early diagnosis possible? Case report

Cardiac involvement in sarcoidosis is difficult to diagnose due to the asymptomatic course in 95% of cases, the inaccessibility and low information content of a heart biopsy, the absence of pathological disorders in routine examination methods or their non-specificity. At the same time, it is cardiac sarcoidosis, along with damage to the nervous system, that is the main cause of mortality in sarcoidosis. Early diagnosis is of decisive importance for preventing complications associated with heart involvement and choosing the right treatment tactics. The positron emission tomography-computed tomography (PET-CT) is a method that can help the doctor in assessing the prevalence of sarcoidosis and verifying latent localizations in patients with a morphologically confirmed disease. The article describes a case of the use of PET/CT for the diagnosis of cardiac sarcoidosis.

A 65-Year-Old Male With Classic Cardiac Sarcoidosis: Case Report and Review of the Literature

Sarcoidosis is a systemic disease characterized by the formation of non-necrotizing granulomas, primarily involving the lungs and other organs such as the heart. The diagnosis of cardiac sarcoidosis can be difficult. The last set of diagnostic guidelines for diagnosis and treatment of cardiac sarcoidosis was published in 2019 by the Japanese Circulation Society (JCS). We describe a case of classic cardiac sarcoidosis and review the literature on clinical presentation, imaging, and management.

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.

Utility of Updated Japanese Circulation Society Guidelines to Diagnose Isolated Cardiac Sarcoidosis

Background In the population with cardiac sarcoidosis (CS), approximately one third lacks extracardiac involvement and is considered to have isolated CS. Recently, the Japanese Circulation Society updated the diagnostic criteria for CS, providing a methodology for diagnosing isolated CS. We aimed to assess the characteristics of isolated CS diagnosed using a multimodal imaging approach according to the updated Japanese Circulation Society guidelines. Methods and Results We retrospectively identified 161 consecutive patients who underwent 18F-fluorodeoxyglucose positron emission tomography for suspected CS between 2012 and 2019. According to the guidelines, patients were classified as having CS with extracardiac involvement, isolated CS, or no CS. We compared the characteristics of multimodality imaging and the prevalence of major adverse cardiovascular events. The Japanese Circulation Society criteria classified 28 patients (17%) as having CS with 4 (2%) with histological confirmation, 21 (13%) as isolated CS, and 112 (70%) as no CS. Compared with CS, isolated CS showed higher left ventricular volume and reduced left ventricular ejection fraction (P<0.01 for all). During the median follow-up period of 522 days, 24 patients had major adverse cardiovascular events. Isolated CS (hazard ratio, 3.35; [95% CI, 1.08-10.39], P=0.036) was independently associated with major adverse cardiovascular events after adjusting for reduced left ventricular ejection fraction and steroid. In the subgroup of 41 patients with serial 18F-fluorodeoxyglucose positron emission tomography evaluation, only updated CS criteria were associated with improvement in myocardial inflammation on 18F-fluorodeoxyglucose positron emission tomography. Conclusions Isolated CS detected using the updated Japanese Circulation Society guidelines was associated with poor event-free survival and should be managed with caution.

Inhibition of type 1 immunity with tofacitinib is associated with marked improvement in longstanding sarcoidosis

Sarcoidosis is an idiopathic inflammatory disorder that is commonly treated with glucocorticoids. An imprecise understanding of the immunologic changes underlying sarcoidosis has limited therapeutic progress. Here in this open-label trial (NCT03910543), 10 patients with cutaneous sarcoidosis are treated with tofacitinib, a Janus kinase inhibitor. The primary outcome is the change in the cutaneous sarcoidosis activity and morphology instrument (CSAMI) activity score after 6 months of treatment. Secondary outcomes included change in internal organ involvement, molecular parameters, and safety. All patients experience improvement in their skin with 6 patients showing a complete response. Improvement in internal organ involvement is also observed. CD4⁺ T cell-derived IFN-γ is identified as a central cytokine mediator of macrophage activation in sarcoidosis. Additional type 1 cytokines produced by distinct cell types, including IL-6, IL-12, IL-15 and GM-CSF, also associate with pathogenesis. Suppression of the activity of these cytokines, especially IFN-γ, correlates with clinical improvement. Our results thus show that tofacitinib treatment is associated with improved sarcoidosis symptoms, and predominantly acts by inhibiting type 1 immunity.

The role of multimodality imaging in patients with heart failure with reduced and preserved ejection fraction

PURPOSE OF REVIEW

The burden of clinical heart failure, both heart failure with a reduced ejection fraction (HFrEF) and with a preserved ejection fraction (HFpEF), continues to increase both nationally and globally. This review summarizes the expanding role of multimodality imaging techniques in the evaluation and management these patients.

RECENT FINDINGS

Echocardiographic assessment for heart failure continues to expand and should include a robust hemodynamic and strain assessment. Nuclear techniques have also continued to evolve and advances including computed tomography attenuation correction for single photon emission-computed tomography positron-emission tomography increase diagnostic accuracy as well as provide information such as myocardial blood flow and viability assessment. Computed tomography imaging, already well established in the assessment of coronary and valvular disease, has increasing utility in the characterization of myopathy, and cardiac magnetic resonance imaging (MRI) continues to expand its role in tissue characterization to a wider breadth of diseases, including right ventricular cardiomyopathy and left ventricle noncompaction.

SUMMARY

Although heart failure remains a clinical diagnosis based on history and examination, early imaging is critical for further assessment. Due to its widespread availability, affordability, and safety, transthoracic echocardiography has long been the mainstay tool for both initial evaluation as well as for periodic surveillance of heart failure patients, but advances in multimodality imaging are occurring at a rapid pace and promise to provide an increasing wealth of data to help manage such patients.

Diagnostic utility of fusion 18F-fluorodeoxyglucose positron emission tomography/cardiac magnetic resonance imaging in cardiac sarcoidosis

BACKGROUND

Although each 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE) has been used to diagnose cardiac sarcoidosis (CS), active CS is still misdiagnosed.

METHODS

Active CS, diagnosed by PET alone, was defined as focal or focal on diffuse FDG uptake pattern. In fusion PET/CMR imaging, using a regional analysis with AHA 17-segment model, the patients were categorized into four groups: (1) PET-/LGE-, (2) PET+/LGE-, (3) PET+/LGE+, and (4) PET-/LGE+. PET+/LGE+ was defined as active CS.

RESULTS

74 Patients with suspected CS were enrolled. Between PET alone and fusion PET/CMR imaging, 20 cases had mismatch evaluations of active CS, and most had diffuse or focal on diffuse FDG uptake pattern on PET alone imaging. 40 Patients fulfilled the 2016 the Japanese Circulation Society diagnostic criteria for CS. The interobserver diagnostic agreement was excellent (κ statistics 0.89) and the overall accuracy for diagnosing CS was 87.8% in fusion PET/CMR imaging, which were superior to those in PET alone imaging (0.57 and 82.4%, respectively). In a sub-analysis of diffuse and focal on diffuse patterns, the agreement (κ statistics 0.86) and overall accuracy (81.8%) in fusion PET/CMR imaging were still better.

CONCLUSIONS

Fusion PET/CMR imaging with regional analysis offered reliable and accurate diagnosis of CS, covering low diagnostic area by FDG-PET alone.

Efficacy of myocardial washout of 99mTc-MIBI/Tetrofosmin for the evaluation of inflammation in patients with cardiac sarcoidosis: comparison with 18F-fluorodeoxyglucose positron emission tomography findings

OBJECTIVE

Both myocardial perfusion scintigraphy and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) are useful for the diagnosis of cardiac sarcoidosis (CS). However, the association between the washout of ^99mTc-labeled tracer and FDG PET has not been established. This study aimed to evaluate the association between the washout of ^99mTc-labeled tracer and FDG PET findings in patients with CS.

METHODS

We retrospectively analyzed 64 patients (65.0 ± 11.2 years, 53% male) with suspected CS who underwent myocardial single-photon emission computed tomography (SPECT) with ^99mTc-labeled tracer and FDG PET. The SPECT images were acquired at 15 min (early images) and 3 h (delayed images) after injection and scored visually using a 17-segment model with a 5-point scoring system. The washout score was defined as the difference between the early and delayed total defect scores. FDG positivity was considered as focal or focal on diffuse patterns on visual assessment, and FDG uptake was quantified by measuring the standardized uptake value (SUV) of each of the 17 segments.

RESULTS

The washout score was significantly higher for the CS group than for the non-CS group (3.0 [-1.0-5.0] vs. 0.0 [-0.5-1.0], p = 0.010). Receiver operating characteristic analysis showed that a washout score of ≥ 2 had the best accuracy for detecting CS (88% sensitivity and 56% specificity) and FDG positivity (71% sensitivity and 89% specificity). In the segment-based analysis of 833 segments from 49 patients, excluding 15 patients with diffuse FDG uptake, the median SUVs for FDG uptake for the washout scores of ≤ 0, 1, and 2 were 2.3 (1.8-3.6), 4.2 (2.9-7.8), and 8.3 (6.5-9.4), respectively (p < 0.001).

CONCLUSIONS

The washout of ^99mTc-labeled tracer can be a useful marker for the evaluation of FDG PET findings in patients with CS.

Combined simultaneous FDG-PET/MRI with T1 and T2 mapping as an imaging biomarker for the diagnosis and prognosis of suspected cardiac sarcoidosis

PURPOSE

To evaluate the diagnostic and prognostic significance of combined cardiac 18F-fluorodeoxyglucose (FDG) PET/MRI with T1/T2 mapping in the evaluation of suspected cardiac sarcoidosis.

METHODS

Patients with suspected cardiac sarcoidosis were prospectively enrolled for cardiac 18F-FDG PET/MRI, including late gadolinium enhancement (LGE) and T1/T2 mapping with calculation of extracellular volume (ECV). The final diagnosis of cardiac sarcoidosis was established using modified JMHW guidelines. Major adverse cardiac events (MACE) were assessed as a composite of cardiovascular death, ventricular tachyarrhythmia, bradyarrhythmia, cardiac transplantation or heart failure. Statistical analysis included Cox proportional hazard models.

RESULTS

Forty-two patients (53 ± 13 years, 67% male) were evaluated, 13 (31%) with a final diagnosis of cardiac sarcoidosis. Among patients with cardiac sarcoidosis, 100% of patients had at least one abnormality on PET/MRI: FDG uptake in 69%, LGE in 100%, elevated T1 and ECV in 100%, and elevated T2 in 46%. FDG uptake co-localized with LGE in 69% of patients with cardiac sarcoidosis compared to 24% of those without, p = 0.014. Diagnostic specificity for cardiac sarcoidosis was highest for FDG uptake (69%), elevated T2 (79%), and FDG uptake co-localizing with LGE (76%). Diagnostic sensitivity was highest for LGE, elevated T1 and ECV (100%). After median follow-up duration of 634 days, 13 patients experienced MACE. All patients who experienced MACE had LGE, elevated T1 and elevated ECV. FDG uptake (HR 14.7, p = 0.002), elevated T2 (HR 9.0, p = 0.002) and native T1 (HR 1.1 per 10 ms increase, p = 0.044) were significant predictors of MACE even after adjusting for left ventricular ejection fraction and immune suppression treatment. The presence of FDG uptake co-localizing with LGE had the highest diagnostic performance overall (AUC 0.73) and was the best predictor of MACE based on model goodness of fit (HR 14.9, p = 0.001).

CONCLUSIONS

Combined cardiac FDG-PET/MRI with T1/T2 mapping provides complementary diagnostic information and predicts MACE in patients with suspected cardiac sarcoidosis.

Cardiac Tuberculosis on 18F-FDG PET Imaging—A Great Masquerader of Cardiac Sarcoidosis

A young gentleman with suspected cardiac sarcoidosis and LV dysfunction whose CMR revealed multifocal subepicardial to mid myocardial linear enhancement in the left ventricular myocardium underwent cardiac 18F-FDG PET imaging. The images revealed patchy regions of increased FDG uptake involving the apical to mid anterolateral, mid to basal anteroseptal/ right ventricular and mildly increased FDG uptake in apical inferior segments of the LV myocardium concordant with CMR findings. Whole body PET CT imaging showed multiple hypermetabolic supra and infra diaphragmatic lymphadenopathy, with no pulmonary lesion identified. Biopsy from the left para aortic lymph node revealed necrotizing granulomatous inflammation consistent with tuberculosis. Based on the histopathological findings of the lymph nodes, diagnosis of cardiac tuberculosis was made, given the similar imaging appearances in both sarcoidosis and TB. This case highlights that cardiac TB although rare, should be included in the differential diagnosis in patients with suspected infiltrative cardiomyopathy, particularly in TB endemic regions.

Side Effects of Oncologic Treatment in the Chest: Manifestations at FDG PET/CT

Fluorodeoxyglucose (FDG) PET/CT is a vital imaging technique used for staging, assessing treatment response, and restaging following completion of therapy in patients who are undergoing or have completed oncologic treatment. A variety of adverse effects from chemotherapy, targeted therapy, immunotherapy, and radiation therapy are commonly encountered in oncologic patients. It is important to be aware of the manifestations of these adverse effects seen on FDG PET/CT images to avoid misinterpreting these findings as disease progression. Furthermore, early identification of these complications is important, as it may significantly affect patient management and even lead to a change in treatment strategy. The authors focus on the FDG PET/CT manifestations of a broad spectrum of oncologic therapy-related adverse effects in the thorax, as well as some treatment-related changes that may potentially mimic malignancy. Online supplemental material is available for this article. ^©RSNA, 2021.

Novel dietary protocol prior to 18F-fluorodeoxyglucose positron emission tomography to evaluate for cardiac sarcoidosis

The diagnosis of cardiac sarcoidosis (CS) is challenging. Recently, guidelines incorporated cardiac positron emission tomography (PET) with 18F-Fluorodeoxyglucose (F18-FDG) as a non-invasive diagnostic modality for the detection and follow-up of CS. However, this technique is dependent of patient dietary preparation to suppress physiological myocardial F18-FDG uptake. We present a case of possible CS which highlights a novel preparation protocol that facilitated appropriate myocardial suppression.

The role of multimodality imaging in diagnosing acute perimyocarditis secondary to Crohn's disease

Background

Acute perimyocarditis is a rare extra-intestinal manifestation in Crohn’s disease which required multimodality imaging to confirm the diagnosis. Here we present a case of acute perimyocarditis as the first presentation of Crohn’s disease. To date, this is the first case presentation reporting the use of ¹⁸F-FDG PET/CT Scan for diagnosing such condition.

Case presentation

A 25-year-old male presented to our hospital with severe persistent pleuritic sharp left-sided chest pain. This was his second hospital admission in the past 4 months for chest pain and diarrhea. At the first hospitalization, he was diagnosed with viral perimyocarditis and irritable bowel syndrome. Laboratory findings, electrocardiogram, and cardiac magnetic resonance imaging results confirm the diagnostic of perimyocarditis. Virology, bacteriology, parasitology, and autoimmune evaluations were unremarkable. Colonoscopy, colorectal biopsy, and ¹⁸FGD PET findings confirmed manifestation of perimyocarditis, Crohn’s disease, and negative for sarcoidosis.

Conclusions

Looking at the overall clinical picture and investigation results of colonoscopy, colorectal biopsy findings, as well as multi-modality imaging with echocardiography, ¹⁸FDG PET—scan and CMRI, the patient was diagnosed to have perimyocarditis attending Chron’s disease flare up as a rare extra-intestinal manifestation.

PET Cardiac Imaging (Perfusion, Viability, Sarcoidosis, and Infection)

Cardiovascular disease is the leading cause of death worldwide. Given the increased availability of radiopharmaceuticals, improved positron emission tomography (PET) camera systems and proven higher diagnostic accuracy, PET is increasingly utilized in the management of various cardiovascular diseases. PET has high temporal and spatial resolution, when compared to Single Photon Emission Computed Tomography. In clinical practice, hybrid imaging with sequential PET and Computed Tomography acquisitions (PET/CT) or concurrent PET and Magnetic Resonance Imaging are standard. This article will review applications of cardiovascular PET/CT including myocardial perfusion, viability, cardiac sarcoidosis/inflammation, and infection.

Predicting risk of sudden cardiac death in patients with cardiac sarcoidosis using multimodality imaging and personalized heart modeling in a multivariable classifier

Cardiac sarcoidosis (CS), an inflammatory disease characterized by formation of granulomas in the heart, is associated with high risk of sudden cardiac death (SCD) from ventricular arrhythmias. Current "one-size-fits-all" guidelines for SCD risk assessment in CS result in insufficient appropriate primary prevention. Here, we present a two-step precision risk prediction technology for patients with CS. First, a patient's arrhythmogenic propensity arising from heterogeneous CS-induced ventricular remodeling is assessed using a novel personalized magnetic-resonance imaging and positron-emission tomography fusion mechanistic model. The resulting simulations of arrhythmogenesis are fed, together with a set of imaging and clinical biomarkers, into a supervised classifier. In a retrospective study of 45 patients, the technology achieved testing results of 60% sensitivity [95% confidence interval (CI): 57-63%], 72% specificity [95% CI: 70-74%], and 0.754 area under the receiver operating characteristic curve [95% CI: 0.710-0.797]. It outperformed clinical metrics, highlighting its potential to transform CS risk stratification.

Ten Questions Cardiologists Should Be Able to Answer About Cardiac Sarcoidosis: Case-Based Approach and Contemporary Review

Sarcoidosis is an inflammatory multisystemic disease of unknown etiology characterized by the formation of noncaseating epithelioid cell granulomas. Cardiac sarcoidosis might be life-threatening and its diagnosis and treatment remain a challenge nowadays. The aim of this review is to provide an updated overview of cardiac sarcoidosis and, through 10 practical clinical questions and real-life challenging case scenarios, summarize the main clinical presentation, diagnostic criteria, imaging findings, and contemporary treatment.

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.

Advanced Nuclear Medicine and Molecular Imaging in the Diagnosis of Cardiomyopathy

OBJECTIVE. The purpose of this article is to summarize the protocol, interpretation, and diagnostic performance of nuclear medicine and molecular imaging in imaging two distinctive, underdiagnosed cardiomyopathies: cardiac amyloidosis and cardiac sarcoidosis. CONCLUSION. Emerging new radiotracers and advanced molecular imaging modalities enable us to noninvasively characterize certain types of cardiomyopathies, including cardiac amyloidosis and cardiac sarcoidosis, with great confidence. We expect to improve recognition and promote the application of such advanced techniques in the imaging and management of these potentially lethal cardiomyopathies.

Management of nonischemic-dilated cardiomyopathies in clinical practice: a position paper of the working group on myocardial and pericardial diseases of Italian Society of Cardiology

: Nonischemic-dilated cardiomyopathy (NIDCM) is an entity that gathers extremely heterogeneous diseases. This awareness, although leading to continuous improvement in survival, has increased the complexity of NIDCM patients' management. Even though the endorsed 'red-flags' approach helps clinicians in pursuing an accurate etiological definition in clinical practice, it is not clear when and how peripheral centers should interact with referral centers with specific expertise in challenging scenarios (e.g. postmyocarditis and genetically determined dilated cardiomyopathy) and with easier access to second-line diagnostic tools and therapies. This position paper will summarize each step in NIDCM management, highlighting the multiple interactions between peripheral and referral centers, from first-line diagnostic workup and therapy to advanced heart failure management and long-term follow-up.

Imaging in Suspected Cardiac Sarcoidosis: A Diagnostic Challenge

Cardiac Sarcoidosis (CS) represents a unique diagnostic dilemma. Guidelines have been recently revised to reflect the established role of sophisticated imaging techniques. Trans-thoracic Echocardiography (TTE) is widely adopted for initial screening of CS. Contemporary TTE techniques could enhance detection of subclinical Left Ventricular (LV) dysfunction, particularly LV global longitudinal strain assessment which predicts event-free survival (meta-analysis of 5 studies, hazard ratio 1.28, 95% confidence interval 1.18-1.37, p < 0.0001). However, despite the wide availability of TTE, it has limited sensitivity and specificity for CS diagnosis. Cardiac Magnetic resonance Imaging (CMR) is a crucial diagnostic modality for suspected CS. Presence of late gadolinium enhancement signifies myocardial scar and enables risk stratification. Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) coupled with myocardial perfusion imaging can identify active CS and guide immunosuppressant therapy. Gallium scintigraphy may be considered although FDG-PET is often preferred. While CMR and FDG-PET provide complementary information in CS evaluation, current guidelines do not recommend which imaging modalities are essential in suspected CS and if so, which modality should be performed first. The utility of hybrid imaging combining both advanced imaging modalities in a single scan is currently being explored, although not yet widely available. In view of recent, significant advances in cardiac imaging techniques, this review aims to discuss changes in guidelines for CS diagnosis, the role of various cardiac imaging modalities and the future direction in CS.

FDG-PET Scan in Sarcoidosis: Clinical and Imaging Indications

BACKGROUND

Sarcoidosis is an unknown etiology multisystem inflammatory disease in which noncaseating granulomas (a collections of inflammatory cells) form and grow in various organs, involving predominantly lungs, intrathoracic lymph node, skin and eyes. It most commonly affects patients between 20 and 40 years old of age but it could be observed at any age (female predominance; rare in Asians).

DISCUSSION

The areas of the body usually affected by sarcoidosis are lungs, skin, or lymph nodes; pulmonary and mediastinal involvement is seen in over of 90% of patients. Less commonly eyes, liver, heart, and brain are involved. Any organ, however, can be affected. Early diagnosis of sarcoidosis can be difficult due to few signs and symptoms in its early stages, and when disease does occur, it may mimic other pathologies, and is made up with chest X-ray, Computed Tomography (CT)-High Resolution CT (HRCT), gallium scans. Fluoro-Deoxy Glucose- Positron Emission Tomography (FDG-PET) is another useful tool to assess the extent of disease and has a potential to evaluate the clinical management of patients responding or not to the treatment.

CONCLUSION

In this review, we would summarize in brief the clinical indications of PDG-PET in sarcoidosis and report the imaging features of the main organs involved in this disease.

Phantom-based image quality assessment of clinical 18F-FDG protocols in digital PET/CT and comparison to conventional PMT-based PET/CT

BACKGROUND

We assessed and compared image quality obtained with clinical 18F-FDG whole-body oncologic PET protocols used in three different, state-of-the-art digital PET/CT and two conventional PMT-based PET/CT devices. Our goal was to evaluate an  improved trade-off between administered activity (patient dose exposure/signal-to-noise ratio) and acquisition time (patient comfort) while preserving diagnostic information achievable with the recently introduced digital detector technology compared to previous analogue PET technology.

METHODS

We performed list-mode (LM) PET acquisitions using a NEMA/IEC NU2 phantom, with activity concentrations of 5 kBq/mL and 25 kBq/mL for the background (9.5 L) and sphere inserts, respectively. For each device, reconstructions were obtained varying the image statistics (10, 30, 60, 90, 120, 180, and 300 s from LM data) and the number of iterations (range 1 to 10) in addition to the employed local clinical protocol setup. We measured for each reconstructed dataset: the quantitative cross-calibration, the image noise on the uniform background assessed by the coefficient of variation (COV), and the recovery coefficients (RCs) evaluated in the hot spheres. Additionally, we compared the characteristic time-activity-product (TAP) that is the product of scan time per bed position × mass-activity administered (in min·MBq/kg) across datasets.

RESULTS

Good system cross-calibration was obtained for all tested datasets with < 6% deviation from the expected value was observed. For all clinical protocol settings, image noise was compatible with clinical interpretation (COV < 15%). Digital PET showed an improved background signal-to-noise ratio as compared to conventional PMT-based PET. RCs were comparable between digital and PMT-based PET datasets. Compared to PMT-based PET, digital systems provided comparable image quality with lower TAP (from ~ 40% less and up to 70% less).

CONCLUSIONS

This study compared the achievable clinical image quality in three state-of-the-art digital PET/CT devices (from different vendors) as well as in two conventional PMT-based PET. Reported results show that a comparable image quality is achievable with a TAP reduction of ~ 40% in digital PET. This could lead to a significant reduction of the administered mass-activity and/or scan time with direct benefits in terms of dose exposure and patient comfort.

PET/CT Imaging in Soft Tissue Infection and Inflammation-An Update

Nuclear medicine procedures, including Ga-67 and labeled leucocyte SPECT/CT as well as PET/CT using 18F-FDG and recently Ga-68 tracers, have found extensive applications in the assessment of infectious and inflammatory processes in general and in soft tissues in particular. Recent published data focus on summarizing the available imaging information with the purpose of providing the referring clinicians with optimized evidence based results. Guidelines and/or recommendations of clinical societies have incorporated nuclear medicine tests (using both labeled leucocytes and FDG) in their suggested work-up for evaluation of infective endocarditis and in certain patients with suspected vascular graft infections. Joint guidelines of the European and American nuclear medicine societies include fever of unknown origin, sarcoidosis, and vasculitis among the major clinical indications that will benefit from nuclear medicine procedures, specifically from FDG PET/CT. Limitations and pitfalls for the use of radiotracers in assessment of infection and inflammation can be related to patient conditions (eg, diabetes mellitus), or to the biodistribution of a specific radiopharmaceutical. Limited presently available data on the use of functional and/or metabolic monitoring of response to infectious and inflammatory processes to treatment and with respect to the effect of drugs such as antibiotics and glucocorticoids on the imaging patterns of these patients need further confirmation.

The heart matters: a review of incidental cardiac uptake on Ga-68 DOTA peptide PET-CT scans

OBJECTIVE

The aim of this study was to evaluate the frequency and relative significance of incidental cardiac uptake on 68Ga-DOTA-peptide PET-CT scans in patients with neuroendocrine tumours/genetic syndromes expressing somatostatin receptors.

METHODS

Scans of 1463 patients who underwent 68Ga-DOTA-peptide PET-CT scans in our department between 2013 and 2018 were retrospectively evaluated for the presence of uptake in the heart and/or its appendages.

RESULTS

out of 1463 patients (1.3%) demonstrated uptake of radio-peptide in the heart and/or its appendages. In 18 out of these 19 patients, the clinicians were unaware of possible cardiac involvement (one patient was a known case of cardiac paraganglioma). The primary neuroendocrine tumours and genetic syndromes associated with those with cardiac uptake of 68Ga-DOTA-peptide were as follows: unknown primary (n = 7), small bowel (n = 6), colon (n = 2), caecum (n = 1), pancreas (n = 1), cardiac paraganglioma (n = 1), Von Hippel Lindau syndrome (n = 1). Amongst the patients with neuroendocrine tumours, demonstrating cardiac uptake of 68Ga-DOTA-peptide, there was no clear association with carcinoid heart disease.

DISCUSSION

Our results are in agreement with established literature. The exact prognostic implication of cardiac involvement in patients with neuroendocrine tumours as well as other genetic syndromes expressing somatostatin receptors is unknown. We hypothesize that early detection and confirmation of cardiac metastasis(es) in these patients and introduction of different treatment regimes (such as Peptide Receptor Radionuclide Therapy), earlier in the course of the disease would reduce the disease burden on the heart and therefore contribute to better patient outcomes.

CONCLUSION

Cardiac involvement is a rare and hitherto less well-studied occurrence in neuroendocrine tumours, with an incidence in the range of 1%. To assess the possible prognostic implications, further detailed multicentre studies are required.

The role of positron emission tomography in the assessment of cardiac sarcoidosis

The myocardium and the cardiovascular system are often involved in patients with sarcoidosis. As therapy should be started as early as possible to avoid complications such as left ventricular dysfunction, a prompt and reliable diagnosis by means of non-invasive tests would be highly warranted. Among other techniques, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has emerged as a high sensitive tool to detect sites of inflammation before morphological changes are visible to conventional imaging techniques. We therefore aim at summarizing the most relevant findings in the literature on the use of 18F-fluorodeoxyglucose PET in the diagnostic workup of cardiac sarcoidosis and to underline future perspectives.

Advanced Imaging in Cardiac Sarcoidosis

Sarcoidosis is a chronic disease of unknown etiology characterized by the presence of noncaseating granulomas. Cardiac involvement in sarcoidosis may lead to adverse outcomes such as advanced heart block, arrhythmias, cardiomyopathy, or death. Cardiac sarcoidosis can occur in patients with established sarcoidosis, or it can be the sole manifestation of the disease. Traditional diagnostic techniques, including echocardiography, have poor sensitivity for diagnosing cardiac sarcoidosis. The accumulating evidence supports the essential role of advanced cardiac imaging modalities such as MRI and PET in diagnosis, risk stratification, and management of patients with cardiac sarcoidosis. The current review highlights important theoretic and practical aspects of using cardiac imaging tools in the evaluation of patients with suspected or established cardiac sarcoidosis.

Gating Approaches in Cardiac PET Imaging

Cardiac PET provides high sensitivity and high negative predictive value in the diagnosis of coronary artery disease and cardiomyopathies. Cardiac, respiratory as well as bulk patient motion have detrimental effects on thoracic PET imaging, in particular on cardiovascular PET imaging where the motion can affect the PET images quantitatively as well as qualitatively. Gating can ameliorate the unfavorable impact of motion additionally enabling evaluation of left ventricular systolic function. In this article, the authors review the recent advances in gating approaches and highlight the advances in data-driven approaches, which hold promise in motion detection without the need for complex hardware setup.

Multimodality Imaging in Restrictive Cardiomyopathies: An EACVI expert consensus document In collaboration with the "Working Group on myocardial and pericardial diseases" of the European Society of Cardiology Endorsed by The Indian Academy of Echocardiography

Restrictive cardiomyopathies (RCMs) are a diverse group of myocardial diseases with a wide range of aetiologies, including familial, genetic and acquired diseases and ranging from very rare to relatively frequent cardiac disorders. In all these diseases, imaging techniques play a central role. Advanced imaging techniques provide important novel data on the diagnostic and prognostic assessment of RCMs. This EACVI consensus document provides comprehensive information for the appropriateness of all non-invasive imaging techniques for the diagnosis, prognostic evaluation, and management of patients with RCM.