The response of FDG uptake to immunosuppressive treatment on FDG PET/CT imaging for cardiac sarcoidosis

Cardiac Sarcoidosis: Utilizing Cardiac MRI and PET-CT

PURPOSEOF REVIEW

Cardiac sarcoidosis is an inflammatory condition that has been associated with deleterious cardiac manifestations. The diagnosis of cardiac sarcoidosis is challenging and can be guided by advanced cardiac imaging.

RECENT FINDINGS

Endomyocardial biopsy lacks sensitivity in confirming a diagnosis of cardiac sarcoidosis. Studies have shown that the use of cardiac magnetic resonance imaging (MRI) and cardiac Positron Emission Testing (PET) are associated with increased sensitivity and specificity in the diagnosis of cardiac sarcoidosis. Cardiac MRI and cardiac PET CT, although distinct entities, are complimentary in the diagnosis, prognostication of major cardiac events, and aid in the treatment algorithm in patients with cardiac sarcoidosis.

Comparative analysis of F-18 FDG PET/CT images between scrub typhus and systemic lupus erythematosus

This study evaluated the use of F-18 fluorodeoxyglucose (FDG) PET/CT imaging to differentiate between scrub typhus and systemic lupus erythematosus (SLE) in patients presenting with lymphadenopathy. We carried out a retrospective analysis of 18 scrub typhus patients and seven SLE patients, using various imaging parameters, including lymph node size, spleen and liver lengths, the distance between the two farthest lesions (Dmax), and assessments of glucose metabolism. On FDG PET images, we measured the maximum standardized uptake value (SUVmax) of the lymph nodes, spleen, and liver and the mean standardized uptake value (SUVmean) of the liver and spleen. The Dmax values of scrub typhus patients were significantly longer than those of SLE patients, indicating that lymphadenopathy is more generalized in the patients with scrub typhus. The SUVmax values for the lymph node, spleen, and liver were also higher in patients with scrub typhus, while the SUVmean of the liver and spleen did not differ between the two groups. This study is the first to compare FDG PET/CT images between these two conditions, suggesting the potential of this imaging modality to provide critical diagnostic distinctions.

Diagnostics, treatment and outcomes of cardiac sarcoidosis in a Norwegian cohort

BACKGROUND

Evidence-based guidelines for cardiac sarcoidosis (CS) regarding use of second- and third-line agents, treatment duration, surveillance and prognostic factors are lacking.

OBJECTIVE

To analyze the clinical presentation, diagnostics, treatment, monitoring and clinical outcomes in a Norwegian cohort.

METHODS

Using discharge diagnoses between 2017 through 2020 from a large tertiary center, we identified 52 patients with CS. We performed a systematic chart review following a pre-specified checklist. The primary outcome of major cardiovascular events (MACE) was defined as a composite of cardiovascular hospitalization, defibrillator therapy, cardiac transplantation, or death.

RESULTS

18-fluorodeoxyglucose positron emission tomography (FDG-PET) showed pathological tracer uptake in 35/36 (97%) of immunosuppression-naïve patients. Immunosuppressive treatment was administered to 49/52 patients (94%) for a median of 43 (IQR 34) months; 69% were treated with second-line (methotrexate, azathioprine, mycophenolate mofetil) and 25% with third-line (rituximab, infliximab) agents, respectively. Rituximab reduced inflammation as assessed by interval FDG-PET imaging and was overall well tolerated. Median duration to first MACE was 6 (IQR 10) months and 17/23 patients (74%) experienced a MACE within 12 months from CS diagnosis. No mortality was recorded and 20% achieved full remission. Age below the median of 53 years at time of diagnosis was associated with an increased risk of a MACE.

CONCLUSION

Long-term immunosuppression including a liberal use of non-steroidal agents, appeared essential in treating CS. Although the burden of cardiovascular events was substantial, the survival was excellent in this contemporary cohort. Prospective randomized studies are urgently needed to define the best therapy for these patients.

Evaluation and Management of Cardiac Sarcoidosis with Advanced Imaging

A high clinical suspicion in the setting of appropriate history, physical exam, laboratory, and imaging parameters is often required to set the groundwork for diagnosis and management. Echocardiography may show septal thinning, evidence of systolic and diastolic dysfunction, along with impaired global longitudinal strain. Cardiac MRI reveals late gadolinium enhancement along with evidence of myocardial edema and inflammation on T2 weighted imaging and parametric mapping. 18F-FDG PET detects the presence of active inflammation and the presence of scar. Involvement of the right ventricle on MRI or PET confers a high risk for adverse cardiac events and mortality.

Prednisone vs methotrexate in treatment naïve cardiac sarcoidosis

BACKGROUND

Side effects limit the long-term use of glucocorticoids in cardiac sarcoidosis (CS), and methotrexate has gained attention as steroid sparing agent although the supporting evidence is poor. This study compared prednisone monotherapy, methotrexate monotherapy or a combination of both, in the reduction of myocardial Fluorine-18 fluorodeoxyglucose (FDG) uptake and clinical stabilization of CS patients.

METHODS AND RESULTS

In this retrospective cohort study, 61 newly diagnosed and treatment naïve CS patients commenced treatment with prednisone (N = 21), methotrexate (N = 30) or prednisone and methotrexate (N = 10) between January 2010 and December 2017. Primary outcome was metabolic response on FDG PET/CT and secondary outcomes were treatment patterns, major adverse cardiovascular events, left ventricular ejection fraction, biomarkers and side effects. At a median treatment duration of 6.2 [5.7-7.2] months, 71.4% of patients were FDG PET/CT responders, and the overall myocardial maximum standardized uptake value decreased from 6.9 [5.0-10.1] to 3.4 [2.1-4.7] (P < 0.001), with no significant differences between treatment groups. During 24 months of follow-up, 7 patients (33.3%; prednisone), 6 patients (20.0%; methotrexate) and 1 patient (10.0%; combination group) experienced at least one major adverse cardiovascular event (P = 0.292). Left ventricular ejection fraction was preserved in all treatment groups.

CONCLUSIONS

Significant suppression of cardiac FDG uptake occurred in CS patients after 6 months of prednisone, methotrexate or combination therapy. There were no significant differences in clinical outcomes during follow-up. These results warrant further investigation of methotrexate treatment in CS patients.

Volume-based 18 F-FDG PET analysis of cardiac sarcoidosis using the descending aorta as a reference tissue

OBJECTIVE

18 F-FDG PET can be used to calculate the threshold value of myocardial volume based on the mean standardised uptake value (SUV mean ) of the aorta to detect highly integrated regions of cardiac sarcoidosis. The present study investigated the myocardial volume when the position and number of volumes of interest (VOIs) were changed in the aorta.

METHODS

The present study examined PET/computed tomography images of 47 consecutive cardiac sarcoidosis cases. VOIs were set at three locations in the myocardium and aorta (descending thoracic aorta, superior hepatic margin and near the pre-branch of the common iliac artery). The volume was calculated for each threshold using 1.1-1.5 times the SUV mean (median of three cross-sections) of the aorta as the threshold to detect high myocardial 18 F-FDG accumulation. The detected volume, correlation coefficient with the visually manually measured volume and the relative error were also calculated.

RESULTS

The optimum threshold value for detecting high 18 F-FDG accumulation was 1.4 times that of the single cross-section of the aorta and showed the smallest relative errors of 33.84% and 25.14% and correlation coefficients of 0.974 and 0.987 for single and three cross-sections, respectively.

CONCLUSION

The SUV mean of the descending aorta may be detected in good agreement with the visual high accumulation by multiplying the same threshold constant for both single and multiple cross-sections.

Preparation and Bioevaluation of a Novel 99mTc-Labeled Glucose Derivative Containing Cyclohexane as a Promising Tumor Imaging Agent

To develop novel tumor imaging agents with high tumor uptake and excellent tumor/non-target ratios, a glucose derivative containing cyclohexane (CNMCHDG) was synthesized and labeled with Tc-99m. [^99mTc]Tc-CNMCHDG was prepared by a kit formulation that was straightforward to operate and fast. Without purification, [^99mTc]Tc-CNMCHDG had a high radiochemical purity of over 95% and great in vitro stability and hydrophilicity (log P = -3.65 ± 0.10). In vitro cellular uptake studies showed that the uptake of [^99mTc]Tc-CNMCHDG was significantly inhibited by pre-treatment with _D-glucose and increased by pre-treatment with insulin. Preliminary cellular studies have demonstrated that the mechanism by which the complex enters into cells may be related to GLUTs. The results of biodistribution and SPECT imaging studies displayed high tumor uptake and good retention of [^99mTc]Tc-CNMCHDG in A549 tumor-bearing mice (4.42 ± 0.36%ID/g at 120 min post-injection). Moreover, [^99mTc]Tc-CNMCHDG exhibited excellent tumor-to-non-target ratios and a clean imaging background and is a potential candidate for clinical transformation.

Hot spot imaging in cardiovascular diseases: an information statement from SNMMI, ASNC, and EANM

This information statement from the Society of Nuclear Medicine and Molecular Imaging, American Society of Nuclear Cardiology, and European Association of Nuclear Medicine describes the performance, interpretation, and reporting of hot spot imaging in nuclear cardiology. The field of nuclear cardiology has historically focused on cold spot imaging for the interpretation of myocardial ischemia and infarction. Hot spot imaging has been an important part of nuclear medicine, particularly for oncology or infection indications, and the use of hot spot imaging in nuclear cardiology continues to expand. This document focuses on image acquisition and processing, methods of quantification, indications, protocols, and reporting of hot spot imaging. Indications discussed include myocardial viability, myocardial inflammation, device or valve infection, large vessel vasculitis, valve calcification and vulnerable plaques, and cardiac amyloidosis. This document contextualizes the foundations of image quantification and highlights reporting in each indication for the cardiac nuclear imager.

The prognostic value of positron emission tomography in the evaluation of suspected cardiac sarcoidosis

OBJECTIVES

To assess the prognostic value of positron emission tomography (PET) imaging in patients undergoing evaluation for known or suspected cardiac sarcoidosis (CS) while not on active immunotherapy.

BACKGROUND

Previous studies have attempted to identify the value of PET imaging to aid in risk stratification of patients with CS, however, most cohorts have included patients currently on immunosuppression, which may confound scan results by suppressing positive findings.

METHODS

We retrospectively analyzed 197 patients not on immunosuppression who underwent 18F-fluorodeoxyglucose (FDG) PET scans for evaluation of known or suspected CS. The primary endpoint of the study was time to ventricular arrhythmia (VT/VF), or death. Candidate predictors were identified by univariable Cox proportional hazards regression. Independent predictors were identified by performing multivariable Cox regression with stepwise forward selection.

RESULTS

Median follow-up time was 531 [IQR 309, 748] days. 41 patients met the primary endpoint. After stepwise forward selection, left ventricular ejection fraction (LVEF) (HR 0.98, 95% CI 0.96-0.99, P = 0.02), history of VT/VF (HR 4.19, 95% CI 2.15-8.17, P < 0.001), and summed rest score (SRS) (HR 1.06, 95% CI 1.02-1.12, P = 0.01) were predictive of the primary endpoint. Quantitative and qualitative measures of FDG uptake on PET were not predictive of clinical events.

CONCLUSIONS

Among untreated patients who underwent PET scans to evaluate known or suspected CS, LVEF, history of VT/VF, and SRS were associated with adverse clinical outcomes.

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.

The role of PET in the management of sarcoidosis

PURPOSE OF REVIEW

PET has emerged as method to determine the location and extent of disease activity in sarcoidosis. As most clinicians do not routinely utilize PET in the management of sarcoidosis, an understanding of the imaging technique is needed to comprehend the impact that PET abnormalities have on diagnosis, prognosis, and treatment.

RECENT FINDINGS

Although PET can detect inflammation because of sarcoidosis throughout the body, it is most often utilized for the diagnosis of cardiac sarcoidosis for which it may provide information about prognosis and adverse events. Whenever PET is combined with cardiac magnetic resonance (CMR), clinicians may be able to increase the diagnostic yield of imaging. Furthermore, PET abnormalities have the potential to be utilized in the reduction or augmentation of therapy based on an individual's response to treatment. Although various biomarkers are used to monitor disease activity in sarcoidosis, an established and reproducible relationship between PET and biomarkers does not exist.

SUMMARY

PET has the potential to improve the diagnosis of sarcoidosis and alter treatment decisions but prospective trials are needed to define the role of PET while also standardizing the performance and interpretation of the imaging modality.

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.

Cytokine Signaling and Matrix Remodeling Pathways Associated with Cardiac Sarcoidosis Disease Activity Defined Using FDG PET Imaging

While cardiac imaging has improved the diagnosis and risk assessment for cardiac sarcoidosis (CS), treatment regimens have consisted of generalized heart failure therapies and non-specific anti-inflammatory regimens. The overall goal of this study was to perform high-sensitivity plasma profiling of specific inflammatory pathways in patients with sarcoidosis and with CS.Specific inflammatory/proteolytic cascades were upregulated in sarcoidosis patients, and certain profiles emerged for CS patients.Plasma samples were collected from patients with biopsy-confirmed sarcoidosis undergoing F-18 fluorodeoxyglucose positron emission tomography (n = 47) and compared to those of referent control subjects (n = 6). Using a high-sensitivity, automated multiplex array, cytokines, soluble cytokine receptor profiles (an index of cytokine activation), as well as matrix metalloproteinase (MMP), and endogenous MMP inhibitors (TIMPs) were examined.The plasma tumor necrosis factor (TNF) and soluble TNF receptors sCD30 and sTNFRI were increased using sarcoidosis, and sTNFRII increased in CS patients (n = 18). The soluble interleukin sIL-2R and vascular endothelial growth factor receptors (sVEGFR2 and sVEGFR3) increased to the greatest degree in CS patients. When computed as a function of referent control values, the majority of soluble cytokine receptors increased in both sarcoidosis and CS groups. Plasma MMP-9 levels increased in sarcoidosis but not in the CS subset. Plasma TIMP levels declined in both groups.The findings from this study were the identification of increased activation of a cluster of soluble cytokine receptors, which augment not only inflammatory cell maturation but also transmigration in patients with sarcoidosis and patients with cardiac involvement.

Corticosteroid and Immunosuppressant Therapy for Cardiac Sarcoidosis: A Systematic Review

Background Corticosteroid therapy for the treatment of clinically manifest cardiac sarcoidosis is generally recommended. Our group previously systematically reviewed the data in 2013; since then, there has been increasing quality and quantity of data and also interest in nonsteroid agents. Methods and Results Studies were identified from MEDLINE, EMBASE, Cochrane Controlled Trials Register, Cochrane Database of Systematic Reviews, and the National Institutes of Health ClinicalTrials.gov database. The quality of included articles was rated using Scottish Intercollegiate Guidelines Network 50. Outcomes examined were atrioventricular conduction, left ventricular function, ventricular arrhythmias, and mortality. A total of 3527 references were retrieved, and 34 publications met the inclusion criteria. There were no randomized trials, and only 2 studies were rated good quality. In the 34 reports (total of 1297 patients), 1125 patients received corticosteroids, 235 received additional or other immunosuppressant therapy, and 97 patients received no therapy. There were 178 patients treated for atrioventricular conduction disease, with 76/178 (42.7%) improving. In contrast, 21 patients were not treated with corticosteroids and/or immunosuppressant therapy, and none of them improved. Therapy was associated with the prevention of deterioration in left ventricular function. A total of 8 publications reported on ventricular arrhythmia burden, and 19 reported on mortality; the data quality was too limited to draw conclusions for the latter 2 outcomes. Conclusions The best quality data relate to atrioventricular nodal conduction and left ventricular function recovery. In both situations, therapy with corticosteroids and/or immunosuppressant therapy were sometimes associated with positive outcomes. The data quality is too limited to draw conclusions for ventricular arrhythmias and mortality.

The rate of myocardial perfusion recovery after steroid therapy and its implication for cardiac events in cardiac sarcoidosis and primarily preserved left ventricular ejection fraction

BACKGROUND

Sarcoidosis is a multisystemic disorder of unknown cause characterized by immune granuloma formation in the involved organs. Few studies have reported on the myocardial perfusion changes by immunosuppression therapy in cardiac sarcoidosis (CS). Additionally, the relationship between myocardial perfusion changes and prognosis is unknown. Therefore, this study aimed to clarify myocardial perfusion recovery after steroid therapy and its prognostic value for major adverse cardiac events (MACE) in patients with CS.

METHODS AND RESULTS

Thirty-eight consecutive patients with CS {median age, 63 [interquartile range (IQR) 51-68] years; 10 men} underwent both 18F-fluorodeoxyglucose positron emission tomography/computed tomography (CT) and electrocardiography-gated single-photon emission CT (SPECT) pre- and post-steroid therapy. Patients with improved or preserved myocardial perfusion after post-therapy were defined as the recovery group and those with worsened myocardial perfusion as the non-recovery group. Twenty-six patients (68%) were categorized as the recovery group. MACE occurred in eight patients. The Kaplan-Meier curves revealed a significantly higher rate of MACE in the non-recovery group (17.4%/y vs 2.9%/y, P = 0.007).

CONCLUSIONS

Myocardial perfusion was recovered by steroid therapy in 61% and preserved in 8% of patients. Myocardial perfusion recovery after steroid therapy was significantly associated with a low incidence of MACE.

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.

Non-steroidal treatment of cardiac sarcoidosis: A systematic review

The treatment of active cardiac sarcoidosis (CS) usually involves immunosuppressive therapy, with the goal of preventing inflammation-induced scar formation. In most cases, steroids remain the first-line treatment for CS. However, given the side effect profile of their long-term use, steroid-sparing therapies are increasingly used. There are no published randomized trials of steroid-sparing agents in CS. We sought to do a systematic review to evaluate the current published data on the use of non-steroidal treatments in the management of CS. We searched the Cochrane Library, Ovid Medline, Ovid Embase, PubMed, and Web of Science Core Collection databases from inception of database to August 2020 to identify the effectiveness of biological or synthetic disease-modifying antirheumatic agents (s- and bDMARDs). Secondary objectives include safety profile as well as the change in the average corticosteroid dose after treatment initiation. Twenty-three studies were ultimately selected for inclusion which included a total of 480 cases of CS treated with a range of both s- and bDMARDs. In all included studies, sDMARDs and bDMARDs were studied in combination with steroids or as second or higher-line treatments after therapeutic failure or intolerance to corticosteroid use. Methotrexate (MTX) and infliximab (IFX) were the most common synthetic and biologic DMARDs studied respectively, reported in about 35% of the studies reviewed. The use of steroid-sparing agents was associated with a reduction in the maintenance steroid dose used. In conclusion, steroids will remain as the cornerstone of anti-inflammatory management in patients with CS until trials on the use and safety profile of other immunosuppressive agents are completed and published.

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.

The Importance of Multimodality Imaging in the Diagnosis and Management of Patients with Infiltrative Cardiomyopathies: An Update

Infiltrative cardiomyopathies (ICMs) comprise a broad spectrum of inherited and acquired conditions (mainly amyloidosis, sarcoidosis, and hemochromatosis), where the progressive buildup of abnormal substances within the myocardium results in left ventricular hypertrophy and manifests as restrictive physiology. Noninvasive multimodality imaging has gradually eliminated endomyocardial biopsy from the diagnostic workup of infiltrative cardiac deposition diseases. However, even with modern imaging techniques’ widespread availability, these pathologies persist in being largely under- or misdiagnosed. Considering the advent of novel, revolutionary pharmacotherapies for cardiac amyloidosis, the archetypal example of ICM, a standardized diagnostic approach is warranted. Therefore, this review aims to emphasize the importance of contemporary cardiac imaging in identifying specific ICM and improving outcomes via the prompt initiation of a targeted treatment.

The prognostic value of quantitating and localizing F-18 FDG uptake in cardiac sarcoidosis

BACKGROUND

There is no identified level of FDG uptake in cardiac sarcoidosis (CS) associated with increased risk of arrhythmias, conduction disease, heart failure, or death. We aim to utilize standardized uptake value (SUV) quantitation and localization to identify patients at increased risk of cardiac events.

METHODS AND RESULTS

F18-FDG PET/CT with MPI was used in CS diagnosis (N = 67). Mean and max SUV were measured and grouped as basal, mid, and apical disease. Post-scan ventricular tachycardia, AICD placement, complete heart block, pacemaker placement, atrial fibrillation, heart failure, and cardiac-related hospital admissions were recorded (mean follow up 2.98 ± 2 years). Poisson regression analysis revealed that max SUV, mean SUV, as well as mean basal SUV, and LVEF were significantly associated with total cardiac events. Max SUV odds ratio (OR) = 1.068 (95% CI 1.024-1.114, P = 0.002), mean SUV OR = 1.059 (95% CI 1.008-1.113, P = 0.023), mean SUV OR = 1.061 (95% CI 1.012-1.112, P = 0.014), scan LVEF OR = 0.731 (95% CI 0.664-0.805, P < 0.001).

CONCLUSIONS

SUV at time of CS diagnosis has significant associations with future cardiac events. Patients with higher SUV, particularly in basal segments, are at increased risk of events. Further studies are needed to identify treatment methods utilizing risk stratification of CS.

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.

The current status of quantitative SPECT/CT in the assessment of transthyretin cardiac amyloidosis

Nuclear medicine bone scans differentiate ATTR cardiomyopathy (ATTR-CM) from light chain cardiac amyloidosis and other myocardial disorders, helping to make the diagnosis without biopsy. Standard bone scans are not absolutely quantitative, so are assessed by comparing the heart to other tissues. The standard visual scoring system compares heart to bone. This accurately diagnoses ATTR-CM and has been validated in a multicenter study, but has limitations. Semiquantitative techniques including heart/contralateral thorax (H/CL) and heart/whole body ratio (H/WB) improve on visual scoring but still rely on extracardiac sites as comparators. Absolute quantitation of myocardial uptake using quantitative SPECT should help overcome these shortcomings. In ATTR-CM, this technique is practical, accurately makes the diagnosis and provides information that is not identical to visual scores. However, more work needs to be done. The reproducibility in ATTR-CM must be tested. Larger studies need to be undertaken to determine whether quantitative SPECT measurements can assess prognosis, disease progression or treatment response. As ATTR-CM is relatively uncommon multicenter trials will help recruit enough subjects to answer these questions. Accurate measurement techniques are needed in ATTR-CM to enable appropriate use of proven therapy and to conduct trials of new therapeutic agents. Quantitative bone scans offer a promising avenue.

Utility of FDG PET and Cardiac MRI in Diagnosis and Monitoring of Immunosuppressive Treatment in Cardiac Sarcoidosis

PURPOSE

To compare the contributions of cardiac MRI and PET in the diagnosis and management of cardiac sarcoidosis (CS), with particular reference to quantitative measures.

MATERIALS AND METHODS

This is a retrospective, observational study of 31 patients (mean age, 45.7 years) with proven extracardiac sarcoidosis and possible CS who were investigated with fluorine 18 fluorodeoxyglucose (FDG) PET/CT and cardiac MRI. Patients were treated at physicians' discretion with repeat combined imaging after an interval of 102-770 days (median, 228 days).

RESULTS

Significant myocardial FDG uptake was shown on visit 1 (myocardial maximum standardized uptake value [SUVmax] > 3.6) in 17 of 22 patients who were subsequently treated. Myocardial SUVmax decreased at follow-up (6.5 to 4.0; P < .01) and was matched by significant decreases in FDG-avid lung and mediastinal node disease. A volumetric measure of myocardium above a threshold SUV (cardiac metabolic volume) decreased from a mean of 42.5 to a mean of 4.1 (P < .001). This was associated with significant improvement in the left ventricular ejection fraction (LVEF) (45.8 increasing to 50.9; P < .031). There was no change in volume of late gadolinium enhancement at treatment. Patients who were untreated showed no change in any FDG PET or cardiac MRI parameter.

CONCLUSION

Myocardial FDG uptake in patients suspected of having CS is presumed to represent active inflammation. When treated with corticosteroids, this resolved or regressed at follow-up, with an improvement in LVEF and FDG-avid thoracic disease. Patients who were untreated showed no change in any parameter. Quantification of FDG-avid myocardium using cardiac metabolic volume is proposed as a useful objective measure for assessing response to therapy.© RSNA, 2020See also commentary by Gutberlet in this issue.

Cardiac Sarcoidosis

Approximately 5% of patients with sarcoidosis will have clinically manifest cardiac involvement presenting with one or more of ventricular arrhythmias, conduction abnormalities, and heart failure. It is estimated that another 20 to 25% of pulmonary/systemic sarcoidosis patients have asymptomatic cardiac involvement (clinically silent disease). Cardiac presentations can be the first (and/or an unrecognized) manifestation of sarcoidosis in a variety of circumstances. Immunosuppression therapy (usually with corticosteroids) has been suggested for the treatment of clinically manifest cardiac sarcoidosis (CS) despite minimal data supporting it. Positron emission tomography imaging is often used to detect active disease and guide immunosuppression. Patients with clinically manifest disease often need device therapy, typically with implantable cardioverter defibrillators (ICDs). The extent of left ventricular dysfunction seems to be the most important predictor of prognosis among patients with clinically manifest CS. In the current era of earlier diagnosis, modern heart failure treatment, and use of ICD therapy, the prognosis from CS is much improved. In a recent Finnish nationwide study, 10-year cardiac survival was 92.5% in 102 patients.

Quantitative interpretation of FDG PET for cardiac sarcoidosis reclassifies visually interpreted exams and potentially impacts downstream interventions

Background: FDG PET is used in cardiac sarcoidosis (CS) diagnosis and management, including decisions about initiation and titration of immunosuppression. However, optimal methods to identify sarcoidosis-related inflammation on these scans is unknown. Traditional interpretive methods for FDG PET rely on qualitative visual analysis, but quantitative techniques including standardized uptake values (SUVs) may be more specific. This study evaluated the diagnostic reclassification of FDG PET studies using quantitative versus qualitative analysis and evaluated the potential impact of reclassification on downstream management and events. Methods: Cardiac-focused FDG PET examinations performed for the evaluation of CS were analyzed, comparing results from the clinically reported visual analysis to quantitative re-analysis using left ventricular maximal SUV values (SUVmax). Net diagnostic reclassification index (NDI) was calculated and compared to admissions, deaths, ICD placements, immunosuppression initiation/escalation. Of 154 exams, 22 were reclassified from positive to negative using quantitative re-analysis whereas only 2 clinically reported negative exams were quantitatively reclassified to positive, leading to a NDI of -13.0%. In the quantitatively negative/clinically reported positive group, 11 patients had immunosuppression adjusted after 22 exams and 4 ICDs were placed. Conclusions: Quantitative re-analysis of FDG PET for CS led to an overall negative diagnostic reclassification from positive to negative. Studies that were clinically reported as positive by visual analysis but reclassified as negative by quantitative analysis had numerous medical interventions but few clinical events. The low event rate suggests the use of quantitative interpretation of FDG PET for CS may help in providing providers with a more targeted therapeutic framework. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 342-353).

Myocardial Positron Emission Tomography for Evaluation of Cardiac Sarcoidosis: Specialized Protocols for Better Diagnosis

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology with various clinical presentations depending on the organs involved. Since cardiac sarcoidosis (CS) portends a higher risk of morbidity and mortality, early diagnosis and aggressive medical treatment are essential to improve the prognosis. ¹⁸F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) has emerged as an important tool with practical advantages in assessing disease activity and monitoring the treatment response in patients with CS. While it has high sensitivity, it also has great variability in specificity, probably due to normal physiologic myocardial FDG uptake, which interferes with the evaluation and follow-up of CS using FDG-PET. This review details the technical aspects of FDG-PET imaging for evaluating and diagnosing CS, assessing disease activity, and monitoring therapeutic response.

Radionuclide Imaging for Cardiac Sarcoidosis: Much Potential Benefit, but Still Much to Do

Sarcoidosis, a multi-organ inflammatory condition commonly involving the heart and leading to high morbidity and mortality, is increasingly prevalent. PET imaging with ¹⁸F-FDG in conjunction with perfusion imaging is increasingly used for diagnosis, disease characterization, and to guide and follow treatment. However, various challenges remain with regard to protocols, interpretation of image findings, and how best to use test results to guide and monitor therapy. Further investigations of the testing technique, as well as better understanding of disease pathophysiology, are needed for better image utility in order to effectively improve patient outcome.

Long-Term Corticosteroid-Sparing Immunosuppression for Cardiac Sarcoidosis

Background

Long‐term corticosteroid therapy is the standard of care for treatment of cardiac sarcoidosis (CS). The efficacy of long‐term corticosteroid‐sparing immunosuppression in CS is unknown. The goal of this study was to assess the efficacy of methotrexate with or without adalimumab for long‐term disease suppression in CS, and to assess recurrence and adverse event rates after immunosuppression discontinuation.

Methods and Results

Retrospective chart review identified treatment‐naive CS patients at a single academic medical center who received corticosteroid‐sparing maintenance therapy. Demographics, cardiac uptake of 18‐fluorodeoxyglucose, and adverse cardiac events were compared before and during treatment and between those with persistent or interrupted immunosuppression. Twenty‐eight CS patients were followed for a mean 4.1 (SD 1.5) years. Twenty‐five patients received 4 to 8 weeks of high‐dose prednisone (>30 mg/day), followed by taper and maintenance therapy with methotrexate±low‐dose prednisone (low‐dose prednisone, <10 mg/day). Adalimumab was added in 19 patients with persistently active CS or in those with intolerance to methotrexate. Methotrexate±low‐dose prednisone resulted in initial reduction (88%) or elimination (60%) of 18‐fluorodeoxyglucose uptake, and patients receiving adalimumab‐containing regimens experienced improved (84%) or resolved (63%) 18‐fluorodeoxyglucose uptake. Radiologic relapse occurred in 8 of 9 patients after immunosuppression cessation, 4 patients on methotrexate‐containing regimens, and in no patients on adalimumab‐containing regimens.

Conclusions

Corticosteroid‐sparing regimens containing methotrexate with or without adalimumab is an effective maintenance therapy in patients after an initial response is confirmed. Disease recurrence in patients on and off immunosuppression support need for ongoing radiologic surveillance regardless of immunosuppression regimen.

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.

Arterial inflammation in young patients with human immunodeficiency virus infection: A cross-sectional study using F-18 FDG PET/CT

BACKGROUND

HIV infection is associated with the risk of development of atherosclerosis at a younger age. We compared arterial inflammation in HIV-infected and HIV-uninfected patients with otherwise low-risk factors for cardiovascular disease (CVD) using FDG PET/CT.

METHODS

242 patients aged 18-40 years with low-risk factors for CVD consisting of 121 HIV-infected patients and 121 HIV-uninfected age- and gender-matched controls were studied, mean age = 34.95 ± 5.46 years. We calculated and compared the target-to-background ratio of FDG uptake in ascending aorta of HIV-infected and non-infected patients.

RESULTS

Median CD4 count and viral load were 375.5 cells/mm3 (range 2-1094) and 6391.00 copies/mL (range 24-1,348,622), respectively. There was slightly higher but significant overlap in the TBR between HIV-infected group compared with control (1.22, 0.87-2.02 vs. 1.12, 0.38-1.40, P < 0.001). TBR was neither affected by CD4 count levels nor the presence or absence of detectable viremia. We also found no significant difference in TBR between male and female patients with HIV infection. We found a weak positive correlation between TBR and CD4 count, TBR and duration of HIV infection, and a very weak negative correlation between TBR and viral load. There was no significant difference in TBR between patients on HAART and those not yet commenced on therapy.

CONCLUSION

Marginally higher TBR with a significant overlap exist in HIV-infected patients compared with control. Arterial F-18 FDG uptake is not affected by the CD 4 count, viral load, gender, or duration of HIV infection.

Complementary Value of Cardiac Magnetic Resonance Imaging and Positron Emission Tomography/Computed Tomography in the Assessment of Cardiac Sarcoidosis

BACKGROUND

Although cardiac magnetic resonance (CMR) and positron emission tomography (PET) detect different pathological attributes of cardiac sarcoidosis (CS), the complementary value of these tests has not been evaluated. Our objective was to determine the value of combining CMR and PET in assessing the likelihood of CS and guiding patient management.

METHODS AND RESULTS

In this retrospective study, we included 107 consecutive patients referred for evaluation of CS by both CMR and PET. Two experienced readers blinded to all clinical data reviewed CMR and PET images and categorized the likelihood of CS as no (<10%), possible (10%-50%), probable (50%-90%), or highly probable(>90%) based on predefined criteria. Patient management after imaging was assessed for all patients and across categories of increasing CS likelihood. A final clinical diagnosis for each patient was assigned based on a subsequent review of all available imaging, clinical, and pathological data. Among 107 patients (age, 55±11 years; left ventricular ejection fraction, 43±16%), 91 (85%) had late gadolinium enhancement, whereas 82 (76%) had abnormal F18-fluorodeoxyglucose uptake on PET, suggesting active inflammation. Among the 91 patients with positive late gadolinium enhancement, 60 (66%) had abnormal F18-fluorodeoxyglucose uptake. When PET data were added to CMR, 48 (45%) patients were reclassified as having a higher or lower likelihood of CS, most of them (80%) being correctly reclassified when compared with the final diagnosis. Changes in immunosuppressive therapies were significantly more likely among patients with highly probable CS.

CONCLUSIONS

Among patients with suspected CS, combining CMR and PET provides complementary value for estimating the likelihood of CS and guiding patient management.

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.

Imaging-Specific Cardiomyopathies: A Practical Guide

Heart failure is a clinical syndrome with a broad spectrum of presentations. Cardiovascular imaging techniques such as echocardiography, cardiovascular magnetic resonance, computed tomography, and nuclear imaging play a crucial role in diagnosis, guiding management, and providing prognostic information. Each of these imaging modalities has their own respective strengths and weaknesses. Cardiac imaging can help differentiate between ischemic and nonischemic cardiomyopathies. Additionally, imaging techniques can display disease-specific findings, aiding in diagnosis of nonischemic cardiomyopathies and can provide a means to monitor response to therapy. The choice of imaging modality in the workup of cardiomyopathy should be based on the specific clinical question and the knowledge of the strengths and limitations of each imaging modality.

Molecular Imaging of the Heart

Multimodality cardiovascular imaging is routinely used to assess cardiac function, structure, and physiological parameters to facilitate the diagnosis, characterization, and phenotyping of numerous cardiovascular diseases (CVD), as well as allows for risk stratification and guidance in medical therapy decision-making. Although useful, these imaging strategies are unable to assess the underlying cellular and molecular processes that modulate pathophysiological changes. Over the last decade, there have been great advancements in imaging instrumentation and technology that have been paralleled by breakthroughs in probe development and image analysis. These advancements have been merged with discoveries in cellular/molecular cardiovascular biology to burgeon the field of cardiovascular molecular imaging. Cardiovascular molecular imaging aims to noninvasively detect and characterize underlying disease processes to facilitate early diagnosis, improve prognostication, and guide targeted therapy across the continuum of CVD. The most-widely used approaches for preclinical and clinical molecular imaging include radiotracers that allow for high-sensitivity in vivo detection and quantification of molecular processes with single photon emission computed tomography and positron emission tomography. This review will describe multimodality molecular imaging instrumentation along with established and novel molecular imaging targets and probes. We will highlight how molecular imaging has provided valuable insights in determining the underlying fundamental biology of a wide variety of CVDs, including: myocardial infarction, cardiac arrhythmias, and nonischemic and ischemic heart failure with reduced and preserved ejection fraction. In addition, the potential of molecular imaging to assist in the characterization and risk stratification of systemic diseases, such as amyloidosis and sarcoidosis will be discussed. © 2019 American Physiological Society. Compr Physiol 9:477-533, 2019.

PET/CT Evaluation of Cardiac Sarcoidosis

The increasing implementation of advanced cardiovascular imaging in the form of cardiac PET/CT has had a significant impact on the management of cardiac sarcoidosis, which continues to evolve. This review summarizes the role of PET/CT imaging in sarcoidosis with a specific focus on (1) indications, (2) patient preparation, (3) test performance, (4) study interpretation, (5) clinical relevance of findings, (6) comparison to alternative imaging modalities, and finally (7) introduction of areas of anticipated development and research.

Multimodal Molecular Imaging: Current Status and Future Directions

Molecular imaging has emerged at the end of the last century as an interdisciplinary method involving in vivo imaging and molecular biology aiming at identifying living biological processes at a cellular and molecular level in a noninvasive manner. It has a profound role in determining disease changes and facilitating drug research and development, thus creating new medical modalities to monitor human health. At present, a variety of different molecular imaging techniques have their advantages, disadvantages, and limitations. In order to overcome these shortcomings, researchers combine two or more detection techniques to create a new imaging mode, such as multimodal molecular imaging, to obtain a better result and more information regarding monitoring, diagnosis, and treatment. In this review, we first describe the classic molecular imaging technology and its key advantages, and then, we offer some of the latest multimodal molecular imaging modes. Finally, we summarize the great challenges, the future development, and the great potential in this field.