Quantitative analysis of myocardial 18F-fluorodeoxyglucose uptake by PET/CT for detection of cardiac sarcoidosis

Tumor-to-blood pool ratio of 18F-fluorodeoxyglucose-positron emission tomography's standardized uptake value as a useful parameter indicating malignant transformation in pancreatic branch-duct intraductal papillary mucinous neoplasm compared to the international Fukuoka guidelines: a retrospective cohort study from surgical resections

BACKGROUND

Identifying malignant transformation in pancreatic branch-duct intraductal papillary mucinous neoplasms (BD-IPMNs) remains challenging, but the standardized uptake value (SUV) obtained from 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT has the potential to become a valuable parameter for differentiation. This study aimed to assess the effectiveness of SUV of FDG-PET/CT in distinguishing low-grade dysplasia (LGD), high-grade dysplasia (HGD), and intraductal papillary mucinous carcinoma (IPMC) within BD-IPMNs.

METHODS

We assessed 58 patients with confirmed BD-IPMN undergoing surgery between 2008 and 2022. Receiver operating characteristic curves were plotted using the tumor-to-blood pool ratio (TBR) of FDG-PET/CT in two scenarios: one considering HGD + IPMC as positive and the other considering only IPMC as positive.

RESULTS

In the cohort of 58 cases, there were 39 females, and the median age was 71 years. The median TBR value was 1.45 (range, 0.35-25.44). The TBRs exhibited a significant correlation with each histopathology (p < 0.001). Furthermore, in the multivariate analysis, TBR was independently significant in both scenarios, with HGD + IPMC defined as malignant (p = 0.001) and with only IPMC defined as malignant (p = 0.024).

CONCLUSIONS

TBR might have the potential to serve as a valuable parameter for indicating malignant transformation in pancreatic BD-IPMNs.

Prospective Analysis of Immunosuppressive Therapy in Cardiac Sarcoidosis With Fluorodeoxyglucose Myocardial Accumulation: The PRESTIGE Study

BACKGROUND

Fluorodeoxyglucose positron emission tomography (18F-FDG-PET) can noninvasively assess active inflammatory myocardium in patients with cardiac sarcoidosis (CS). Prednisolone (PSL) is the initial drug of choice for active CS; however, its efficacy has not been prospectively evaluated. Moreover, there are no alternative systematic treatment strategies.

OBJECTIVES

The goal of this study was to evaluate the efficacy of methotrexate (MTX) in patients refractory to PSL assessed by using cardiac metabolic activity (CMA) in 18F-FDG-PET.

METHODS

A total of 59 patients with active CS were prospectively enrolled. CMA (standardized uptake value × accumulation area) was used as an indicator of active inflammation, and a 6-month regimen of PSL therapy was introduced, followed by a second FDG scan. Poor responders to PSL therapy (CMA reduction rate <70%) and patients with recurrent CS (CMA reduction rate ≥70% after initial PSL therapy but CMA recurred after an additional 6 months of therapy) were randomly assigned to the MTX or repeat PSL (re-PSL) therapy groups for another 6 months.

RESULTS

Fifty-six patients completed the initial 6-month PSL therapy regimen. Median CMA reduced from 203.3 to 1.0 (P < 0.001), and 47 patients were allocated to the response group, 9 to the poor response group, and 2 to the recurrent group. Accordingly, 11 patients were randomly assigned to the MTX (n = 5) or re-PSL (n = 6) groups. After 6 months, neither group showed a significant reduction in CMA values. MTX was comparable to re-PSL in reducing CMA.

CONCLUSIONS

The 6-month regimen of PSL was a potent therapeutic tool for active CS. When MTX was added to low-dose PSL in patients refractory to the initial PSL therapy, there was no significant difference compared with re-PSL. Further studies are needed to evaluate the therapeutic potential of MTX for active CS, including how MTX works when it is administered in higher doses or for longer periods.

Diagnostic values of delayed additional FDG PET/CT scan in the evaluation of cardiac sarcoidosis

OBJECTIVE

This study aimed to compare the contribution of 18F-fluorodepxyglucose (FDG) positron (PET)/ computed tomography (CT) acquisition of early and delayed scans in patients with cardiac sarcoidosis (CS).

METHODS

Twenty-three patients with CS (median age: 69 years; 11 women) were retrospectively evaluated using dual-phase FDG PET/CT. All patients were instructed to consume a low-carbohydrate diet followed by fasting for 18 h before FDG injection to reduce physiological myocardial uptake. PET/CT was acquired at 60 min (early) and 100 min (delayed) after FDG administration. Focal and focal on diffuse uptake on visual analysis was considered positive for CS. A semi-quantitative analysis was performed using the maximum standardized uptake value (SUVmax) of the cardiac lesion and the mean SUV (SUVmean) of the blood pool.

RESULTS

Significant myocardial FDG uptake was observed in 21 patients (91.3%) in the early acquisition group and in 23 patients in the delayed scan group (100%). Compared to the early scan, the delayed scan showed a significantly higher SUVmax of the cardiac lesion [median, 4.0; IQR (interquartile range, 2.9 to 7.0) vs. 5.8 (IQR 3.7 to 10.1); P = 0.0030] and a significantly lower SUVmean of blood pool [median, 1.3 (IQR, 1.2 to 1.4) vs. 1.1 (IQR, 0.9 to 1.2); P < 0.0001].

CONCLUSION

Delayed FDG PET/CT acquisition improves detection accuracy in patients with CS compared to early scans with washout of the blood pool activity. Therefore, it can contribute to a more accurate assessment of CS.

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.

Effect of Immunosuppressive Therapy and Biopsy Status in Monitoring Therapy Response in Suspected Cardiac Sarcoidosis

BACKGROUND

Patients with suspected cardiac sarcoidosis frequently undergo fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) imaging to assess disease activity at baseline and after treatment initiation.

OBJECTIVES

This study investigated the effect of immunosuppressive therapy and biopsy status to achieve complete treatment response (CTR), partial treatment response (PTR), or no response (NR) on myocardial FDG-PET/CT.

METHODS

This study analyzed 83 patients with suspected cardiac sarcoidosis (aged 53 ± 1.8 years, 71% were male, 69% were White, 61% had a history of biopsy-confirmed sarcoidosis) who were treatment naive, had evidence of myocardial FDG at baseline, and underwent repeat PET imaging after treatment initiation. CTR was graded visually, and PTR/NR were measured both visually and quantitatively using the total glycolytic activity. Patients were also evaluated for the occurrence of death, sustained ventricular arrhythmias, and heart failure admissions.

RESULTS

Overall, 59 patients (71%) achieved CTR/PTR (30%/41%) at follow-up scan (P = 0.04). Total glycolytic activity and visual estimate of PTR/NR had excellent agreement (κ = 0.86 [95% CI: 0.72-0.99]; P < 0.0001). In patients receiving prednisone only, the highest rates of CTR/PTR were observed in patients initiated on moderate or high dose (P < 0.01). In a regression model, moderate prednisone start dose (P = 0.03) was more strongly associated with achieving CTR/PTR than was high prednisone start dose. However, the latter patients were tapered faster between start dose and follow-up scan (P < 0.01). After a median follow-up of 4.7 (IQR: 3.1-7.8) years, patients who were biopsy-proven (vs non-biopsy-proven; P = 0.029) and with preserved left ventricular function (P = 002) were less likely to experience major adverse cardiac events. Outcomes based on treatment response status (CTR vs PTR vs NR; P = 0.23) were not significantly different.

CONCLUSIONS

Among patients with suspected sarcoidosis and evidence of myocardial inflammation, treatment response by serial FDG-PET was variable, but a favorable response was more common when using moderate-to-high intensity prednisone dose. Biopsy-proven individuals and those with preserved systolic function were less likely to experience adverse outcomes during follow-up.

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.

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

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

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.

The tumor‐to‐liver ratio of the standardized uptake value is a useful FDG‐PET/CT parameter for predicting malignant intraductal papillary mucinous neoplasm of the pancreas

Background

The present study aimed to investigate the efficacy of positron emission tomography with 18Fluoro‐deoxyglucose (FDG‐PET/CT) for predicting malignant intraductal papillary mucinous neoplasm (IPMN).

Methods

The records of 88 patients pathologically diagnosed with IPMN after surgery at Ehime University Hospital and Ehime Prefectural Central Hospital from April 2009 to December 2020 were retrospectively reviewed. The patients’ characteristics, blood chemistry, and imaging examinations were evaluated as potential predictors of malignant IPMN. Of the PET/CT results, the maximum standardized uptake value (SUVmax) of the tumor, the tumor‐to‐blood pool ratio of the SUV (TBR), and the tumor‐to‐liver ratio of the SUV (TLR) were compared.

Results

On pathology, the diagnosis was adenoma (IPMA) in 40 patients, high‐grade dysplasia (HGD) in 26 patients, and carcinoma (IPMC) in 22 patients. HGD and IPMC were defined as malignant IPMN. On multivariate analyses, TLR ≥ 1.3 and high‐risk stigmata were independent predictors of malignant IPMN (P = .001 and P = .007, respectively). When both HRS and TLR ≥ 1.3 were present, the positive predictive value for malignancy was 88.2%. Furthermore, TLR was significantly higher for patients with IPMC than with HGD (P = .039).

Conclusion

TLR can be a useful predictor for differentiating benign from malignant IPMN and may be associated with postoperative outcomes.

Advances in Diagnostic Imaging for Cardiac Sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown etiology, and its clinical presentation depends on the affected organ. Cardiac sarcoidosis (CS) is one of the leading causes of death among patients with sarcoidosis. The clinical manifestations of CS are heterogeneous, and range from asymptomatic to life-threatening arrhythmias and progressive heart failure due to the extent and location of granulomatous inflammation in the myocardium. Advances in imaging techniques have played a pivotal role in the evaluation of CS because histological diagnoses obtained by myocardial biopsy tend to have lower sensitivity. The diagnosis of CS is challenging, and several approaches, notably those using positron emission tomography and cardiac magnetic resonance imaging (MRI), have been reported. Delayed-enhanced computed tomography (CT) may also be used for diagnosing CS in patients with MRI-incompatible devices and allows acceptable evaluation of myocardial hyperenhancement in such patients. This article reviews the advances in imaging techniques for the evaluation of CS.

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

BACKGROUND

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

METHODS AND RESULTS

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

RESULTS

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

CONCLUSION

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

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

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

Prognosis and recurrence in cardiac sarcoidosis: Serial assessment of BMIPP SPECT and FDG-PET

BACKGROUND

We analyzed 18F-Fludeoxyglucose positron emission tomography (FDG-PET) and 123I-betamethyl-p-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) performed for cardiac sarcoidosis (CS) patients taking prednisolone, identified recurrence by FDG-PET, and investigated BMIPP as a recurrence and prognostic factor in CS.

METHODS AND RESULTS

CS patients who underwent BMIPP and FDG-PET within 2 months were enrolled. The recurrence-free group included patients with standardized uptake value (SUVmax) < 4 in the myocardium consecutively for ≥ 2 years. The total BMIPP SPECT defect score (BDS) was used to estimate myocardial damage. The predictability of the initial BDS and SUVmax for major adverse cardiac events (MACE) was analyzed using Kaplan-Meier analysis. Overall, 73 patients and 250 BMIPP and FDG-PET sets were analyzed retrospectively (mean follow-up, 3.5 years). The BDS was significantly greater for the recurrence group (N = 21) vs recurrence-free group (20 ± 13 vs 14 ± 12, P = 0.041). Patients with BDS ≥16 had a significantly higher MACE rate than patients with BDS < 16 (log-rank test, P = 0.016). However, MACE occurrence was comparable between patients with SUVmax ≥ 4 and < 4.

CONCLUSIONS

BDS is a predictive marker of recurrence and MACE. SUV is not related to MACE. Recurrence, defined by prednisolone treatment-induced SUV variability, was observed in approximately 30% of CS patients.

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.

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.

CASPA (CArdiac Sarcoidosis in PApworth) improving the diagnosis of cardiac involvement in patients with pulmonary sarcoidosis: protocol for a prospective observational cohort study

INTRODUCTION

Sarcoidosis is a multisystem disease, predominantly affecting the lungs but can involve the heart, resulting in cardiac sarcoidosis (CS). Patients require MRI/Positron Emission Tomography (PET) scans for diagnosis. Echocardiography, ECG and Holter monitoring may be indicative but not diagnostic alone. Patients can present late with conduction defects, heart failure or sudden death. The CASPA (CArdiac Sarcoidosis in PApworth) study protocol aims to (1) use MRI to identify CS prevalence; (2) use speckle-tracking echocardiography, signal averaged ECG and Holter monitoring to look for diagnostic pathways; and (3) identify serum proteins which may be associated with CS.

METHODS AND ANALYSIS

Participants with pulmonary sarcoidosis (and no known cardiac disease) from Royal Papworth Hospital will have the following: cardiac MRI with late gadolinium, two-dimensional transthoracic echocardiography with speckle tracking, signal averaged ECG and 24-hour Holter monitor. They will provide a serum sample for brain natriuretic peptide levels and proteomics by liquid chromatography coupled to high-resolution mass spectrometry. All data will be collected on OpenClinica platform and analysed approximately 6 months after final patient recruitment.

ETHICS AND DISSEMINATION

The Camden & Kings Cross Research Ethics Committee approved the protocol (REC number: 17/LO/0667). Integrated Research Approval System (IRAS) 222 720. Dissemination of findings will be via conference presentations and submitted to peer-reviewed journals.

Features and clinical impact of extra-cardiac lesions with 18F-fluorodeoxyglucose positron emission tomography in patients with suspected cardiac sarcoidosis

Background

Sarcoidosis is a systemic inflammatory disorder and can often affect any other organs beyond the heart. Whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) is used to detect not only cardiac but also extra-cardiac involvement of sarcoidosis. However, the features and clinical impact of extra-cardiac lesions have not yet been fully elucidated. Therefore, this study aimed to clarify these using FDG-PET.

Methods and results

We enrolled 120 consecutive patients with abnormal findings clinically suggesting cardiac sarcoidosis who underwent whole-body FDG-PET. In this study, a patient with suspected cardiac sarcoidosis was defined as one having both clinically suspected findings and FDG-PET positive cardiac uptake. Subsequently, a total of 36 patients with suspected cardiac sarcoidosis were found and analyzed. Extra-cardiac involvement was detected in 35 lesions of 14 patients (39% per patient). In particular, the extra-cardiac lesions were widely distributed throughout the body, and mediastinal/hilar lymph node involvement was most commonly observed. In most of the patients (93% per patient, 13/14), the extra-cardiac lesions were localized in the regions that were considered more accessible with less risk of complication compared with endomyocardial biopsy (EMB). Based on the FDG-PET findings, 8 patients underwent extra-cardiac biopsy without complication, and its diagnostic sensitivity for histological sarcoidosis was high (75%, 6/8). Moreover, FDG-PET-guided extra-cardiac biopsy could confirm histological sarcoidosis in 4 lesions that EMB failed to prove.

Conclusions

Extra-cardiac involvement in patients with suspected cardiac sarcoidosis was relatively high. FDG-PET-guided extra-cardiac biopsy may be safe and useful for the imaging based diagnosis of cardiac sarcoidosis.

Diagnosis and Detection of Sarcoidosis. An Official American Thoracic Society Clinical Practice Guideline

Background: The diagnosis of sarcoidosis is not standardized but is based on three major criteria: a compatible clinical presentation, finding nonnecrotizing granulomatous inflammation in one or more tissue samples, and the exclusion of alternative causes of granulomatous disease. There are no universally accepted measures to determine if each diagnostic criterion has been satisfied; therefore, the diagnosis of sarcoidosis is never fully secure.

Methods: Systematic reviews and, when appropriate, meta-analyses were performed to summarize the best available evidence. The evidence was appraised using the Grading of Recommendations, Assessment, Development, and Evaluation approach and then discussed by a multidisciplinary panel. Recommendations for or against various diagnostic tests were formulated and graded after the expert panel weighed desirable and undesirable consequences, certainty of estimates, feasibility, and acceptability.

Results: The clinical presentation, histopathology, and exclusion of alternative diagnoses were summarized. On the basis of the available evidence, the expert committee made 1 strong recommendation for baseline serum calcium testing, 13 conditional recommendations, and 1 best practice statement. All evidence was very low quality.

Conclusions: The panel used systematic reviews of the evidence to inform clinical recommendations in favor of or against various diagnostic tests in patients with suspected or known sarcoidosis. The evidence and recommendations should be revisited as new evidence becomes available.

PET/Computed Tomography in Pulmonary and Thoracic Inflammatory Diseases (Including Cardiac Sarcoidosis): The Current Role and Future Promises

¹⁸F-fluorodeoxyglucose PET/computed tomography (CT) can play a valuable adjunct role in initial and post-treatment assessment of thoracic and pulmonary inflammatory disorders and is particularly helpful when the conventional biomarkers and anatomical imaging are non-contributory or inconclusive. PET/CT can potentially help in chronic obstructive pulmonary disease (COPD). Quantitative regional parameters of inflammation, perfusion, and ventilation estimated by PET/CT have the potential to cause a paradigm shift in the management of COPD. This article highlights the role of PET/CT in thoracic inflammatory disorders, with an overview of newer aspects such as quantification, disease phenotyping, new tracers, and new techniques.

18-FDG-PET in a patient cohort suspected for cardiac sarcoidosis: Right ventricular uptake is associated with pathological uptake in mediastinal lymph nodes

INTRODUCTION

In up to 65% of cardiac sarcoidosis patients, the disease is confined to the heart. Diagnosing isolated cardiac sarcoidosis is challenging due to the low sensitivity of endomyocardial biopsy. If cardiac sarcoidosis is part of biopsy-confirmed systemic sarcoidosis, the diagnosis can be based on cardiac imaging studies. We compared the imaging features of patients with isolated cardiac FDG uptake on positron emission tomography with those who had findings indicative of systemic sarcoidosis.

MATERIALS AND METHODS

137 consecutive cardiac FDG-PET/CT studies performed on subjects suspected of having cardiac sarcoidosis were retrospectively analyzed.

RESULTS

33 patients had pathological left ventricular FDG uptake, and 12 of these also had pathological right ventricular uptake. 16/33 patients with pathological cardiac uptake had pathological extracardiac uptake. 10/12 patients with both LV- and RV-uptake patterns had extracardiac uptake compared to 6/21 of those with pathological LV uptake without RV uptake. SUVmax values in the myocardium were higher among patients with abnormal extracardiac uptake. The presence of extracardiac uptake was the only imaging-related factor that could predict a biopsy indicative of sarcoidosis.

CONCLUSION

Right ventricular involvement seems to be more common in patients who also have findings suggestive of suspected systemic sarcoidosis, compared with patients with PET findings indicative of isolated cardiac disease.

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.

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.

Discrepancy between significant fibrosis and active inflammation in patients with cardiac sarcoidosis: combined and image fusion analysis of cardiac magnetic resonance and 18F fluorodeoxyglucose positron emission tomography

Background

Diagnosis and evaluation of cardiac sarcoidosis (CS) are mainly based on the combined use of cardiac magnetic resonance imaging (CMR) and ¹⁸F fludeoxyglucose positron emission tomography (FDG). Though these modalities can detect the pathological feature of the disease, combined assessment has not been fully examined. Multimodality image fusion is known to be useful for further comprehension, while most image interpretation is performed with a side by side comparison in clinical routine. We investigated the similarity and discrepancy of active inflammation, regional fibrosis, and wall function by image fusion of CMR and FDG.

Methods

Patients with CS who underwent both CMR and FDG were retrospectively enrolled. The extent of myocardial late gadolinium enhancement (LGE) in left ventricle (LGE volume), cardiac function, and volume (left ventricular ejection fraction, LVEF; end-diastolic volume, EDV) was measured from CMR. The FDG uptake in whole myocardium (whole SUVmax), cardiac metabolic volume (CMV), and cardiac metabolic activity (CMA) was calculated from FDG. CMR and FDG were fused and divided into AHA 17 model for segmental analysis. Wall motion, the magnitude of LGE in myocardial wall (LGE%wall), and corresponding FDG uptake (segmental SUVmax) were analyzed.

Results

Forty-one patients were retrospectively enrolled. In patients with FDG uptake, LVEF inversely correlated to LGE volume and positively correlated to SUVmax (r = − 0.56, p < 0.0001, and r = 0.08, p = 0.048, respectively). Discrepancy between LGE volume and CMV showed a significant positive correlation to whole SUVmax and CMA (r = 0.49, p < 0.0001, and r = 0.96, p < 0.0001, respectively). In image fusion analysis, segmental SUVmax showed a significant inverse correlation to LGE%wall (Spearman’s rank correlation coefficient; r = − 0.15, p = 0.008). LGE%wall also showed significant inverse correlation to wall motion (r = − 0.13, p = 0.0011).

Conclusion

Combined and fusion analysis with CMR and FDG demonstrated the discrepancy of myocardial inflammation and extensive fibrosis. Active inflammation was present in the earlier stage of myocardial fibrosis and was found to be less in the wall with advanced fibrosis and remodeling. Combined analysis of CMR and FDG can incrementally reclassify the pathological stage of CS.

18F-FDG-PET in Finnish patients with clinical suspicion of cardiac sarcoidosis: Female sex and history of atrioventricular block increase the prevalence of positive PET findings

INTRODUCTION

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a non-invasive imaging modality that has been shown to be a feasible method to demonstrate myocardial inflammation. The aim of this study was to identify the patients suspected of having cardiac sarcoidosis (CS), who are most likely to benefit from PET imaging.

MATERIALS AND METHODS

137 patients suspected of having CS underwent a dedicated cardiac FDG-PET examination at Tampere University Hospital between August 2012 and September 2015. These examinations were retrospectively analyzed.

RESULTS

33 and 12 of the 137 patients had abnormal left and right ventricular (LV and RV) FDG-uptake, respectively. Abnormal LV-uptake and RV-uptake were significantly associated with female sex and a history of advanced AV-block (P < 0.05). Abnormal RV-uptake was also associated with ventricular tachycardia and atrial fibrillation (P < 0.05). 56% of the 27 female patients with a history of AV-block had a pathological PET finding compared to only 6% of the 49 male patients without a history of AV-block. There were 17 female patients with history of both AV-block and ventricular tachycardia, 71% of them had abnormal PET finding.

CONCLUSIONS

Abnormal FDG-PET findings were associated with female sex, AV-block, and arrhythmias in this clinical cohort.

Heterogeneity of myocardial 2-[18F]fluoro-2-deoxy-D-glucose uptake is a typical feature in cardiac sarcoidosis: a study of 231 patients

Aims

The goal of the investigation was to evaluate whether a semi-quantitative method reflecting myocardial 2-[18F]fluoro-2-deoxy-D-glucose (FDG) uptake heterogeneity has added value in addition to visual analysis in the diagnosis of cardiac sarcoidosis (CS).

Methods and results

This retrospective analysis included 271 consecutive patients suspected of CS attending cardiac positron emission tomography combined with computed tomography (PET-CT) at our institution between 2007 and 2013. Visual analysis of PET-CT and semi-quantitative analysis of heterogeneity [coefficient of variation (CoV)] of myocardial FDG uptake were performed. The presence of CS and initial symptoms were verified from patient data. The criteria for CS included histological verification from the myocardium or from an extracardiac site. Thirty cancer patients without cardiac disease were included as controls. CS was diagnosed in 48/231 (20.8%) of analysed patients. Of these, 13 (27.1%) had no extracardial signs of the disease and 30 (62.5%) had FDG positive mediastinal lymph nodes. Visual analysis of PET-CT identified 48.9% of the CS patients. We found a cut-off value of 0.184 for CoV to have the best accuracy to detect CS from a patient population with suspected CS (75.0% sensitivity and 51.4% specificity). Compared to controls, CoV identified CS patients with a good accuracy (68.8% sensitivity and 93.3% specificity). CS patients with FDG positive mediastinal lymph nodes had higher CoV than CS patients without lymph node involvement (0.282 vs. 0.208, P = 0.016). CS patients with more severe initial symptoms had a higher CoV than patients with more benign symptoms (0.283 vs. 0.195, P = 0.01).

Conclusion

CoV provides a good addition to visual analysis of cardiac FDG PET-CT in diagnosis of CS. As a semi-quantitative measure, it reduces intra-observer variability. It also seems to indicate more severe disease, but to confirm this, prospective studies are needed.

Cardiac Magnetic Resonance Imaging for Diagnosis of Cardiac Sarcoidosis: A Meta-Analysis

Background

Cardiac magnetic resonance imaging (CMR) is an effective technique for the diagnosis of cardiac sarcoidosis (CS). The efficacy of CMR versus the Japanese Ministry of Health and Welfare (JMHW) guidelines considered as standard criterion for the diagnosis of CS remains to be elucidated.

Methods

In this systematic review and meta-analysis, we aimed at assessing the diagnostic accuracy of CMR in cardiac sarcoidosis. We searched on PubMed from January 1, 1980, to March 28, 2018, on Embase from January 1, 1980, to March 29, 2018, and on the Cochrane Library from January 1, 1980, to April 1, 2018, using a strategy based on the search terms (sarcoidosis and magnetic resonance imaging) independently. We analyzed the data obtained with Revman 5.3 and Stata 14.0 software.

Results

Eight studies with a total of 649 participants met the inclusion criteria, and data were extracted. CMR had an overall sensitivity of 0.93 (95% confidence interval (CI), 0.87–0.97) and specificity of 0.85 (95% CI, 0.68–0.94) for the diagnosis of cardiac sarcoidosis. The area under the summary receiver operating characteristic (SROC) curve was 0.95 (95% CI, 0.93–0.97). The subgroup analysis via public year showed that studies between 2011 and 2017 had an overall sensitivity of 0.95 (95% CI, 0.88–0.98) and specificity of 0.92 (95% CI, 0.49–0.99), with an area under the SROC curve being 0.96.

Conclusions

The results of this meta-analysis suggest that CMR could be used for the diagnosis of cardiac sarcoidosis and screening of patients suspected of CS. With the improvement of the technique, the diagnostic accuracy of MRI has improved.

Cardiac sarcoidosis classification with deep convolutional neural network-based features using polar maps

AIMS

The aim of this study was to determine whether deep convolutional neural network (DCNN)-based features can represent the difference between cardiac sarcoidosis (CS) and non-CS using polar maps.

METHODS

A total of 85 patients (33 CS patients and 52 non-CS patients) were analyzed as our study subjects. One radiologist reviewed PET/CT images and defined the left ventricle region for the construction of polar maps. We extracted high-level features from the polar maps through the Inception-v3 network and evaluated their effectiveness by applying them to a CS classification task. Then we introduced the ReliefF algorithm in our method. The standardized uptake value (SUV)-based classification method and the coefficient of variance (CoV)-based classification method were used as comparative methods.

RESULTS

Sensitivity, specificity and the harmonic mean of sensitivity and specificity of our method with the ReliefF algorithm were 0.839, 0.870 and 0.854, respectively. Those of the SUVmax-based classification method were 0.468, 0.710 and 0.564, respectively, and those of the CoV-based classification method were 0.655, 0.750 and 0.699, respectively.

CONCLUSION

The DCNN-based high-level features may be more effective than low-level features used in conventional quantitative analysis methods for CS classification.

Use of 18F-FDG PET/CT texture analysis to diagnose cardiac sarcoidosis

PURPOSE

¹⁸F-fluorodeoxyglocose positron emission tomography (FDG PET) plays a significant role in the diagnosis of cardiac sarcoidosis (CS). Texture analysis is a group of computational methods for evaluating the inhomogeneity among adjacent pixels or voxels. We investigated whether texture analysis applied to myocardial FDG uptake has diagnostic value in patients with CS.

METHODS

Thirty-seven CS patients (CS group), and 52 patients who underwent FDG PET/CT to detect malignant tumors with any FDG cardiac uptake (non-CS group) were studied. A total of 36 texture features from the histogram, gray-level co-occurrence matrix (GLCM), gray-level run length matrix (GLRLM), gray-level zone size matrix (GLZSM) and neighborhood gray-level difference matrix (NGLDM), were computed using polar map images. First, the inter-operator and inter-scan reproducibility of the texture features of the CS group were evaluated. Then, texture features of the patients with CS were compared to those without CS lesions.

RESULTS

Twenty-eight of the 36 texture features showed high inter-operator reproducibility with intraclass correlation coefficients (ICCs) over 0.80. In addition, 17 of the 36 showed high inter-scan reproducibility with ICCs over 0.80. The SUVmax showed no difference between the CS and non-CS group [7.36 ± 2.77 vs. 8.78 ± 4.65, p = 0.45, area under the curve (AUC) = 0.60]. By contrast, 16 of the 36 texture features could distinguish CS from non-CS grsoup with AUC > 0.80. Multivariate logistic regression analysis after hierarchical clustering concluded that long-run emphasis (LRE; P = 0.0004) and short-run low gray-level emphasis (SRLGE; P = 0.016) were significant independent factors that could distinguish between the CS and non-CS groups. Specifically, LRE was significantly higher in CS than in non-CS (30.1 ± 25.4 vs. 11.4 ± 4.6, P < 0.0001), with high diagnostic ability (AUC = 0.91), and had high inter-operator reproducibility (ICC = 0.98).

CONCLUSIONS

The texture analysis had high inter-operator and high inter-scan reproducibility. Some of texture features showed higher diagnostic value than SUVmax for CS diagnosis. Therefore, texture analysis may have a role in semi-automated systems for diagnosing CS.

Cardiac sarcoidosis - an expert review for the chest physician

Introduction: Sarcoidosis is a multisystem granulomatous disease predominantly affecting the lungs, with increased risk of cardiovascular disease, pulmonary hypertension and cardiac sarcoidosis (CS), the latter due to direct granuloma infiltration. Sarcoidosis is often managed by chest physicians who need to understand the diagnostic pathways and initial management plans for patients with cardiac involvement. Areas covered: The most serious consequence of CS is sudden cardiac death due to ventricular tachyarrhythmias or complete atrioventricular block. Additional complications include atrial arrhythmias and congestive cardiac failure. There are no internationally accepted screening pathways, but a combination of history, clinical examination and ECG detects up to 85% of cases. Newer modalities including signal-averaged ECG and speckle-tracking echocardiography increase identification of patients who require a definitive diagnosis. Early immunosuppression reduces the risk of conduction abnormalities and incidence of supraventricular arrhythmias. Management of ventricular arrhythmias requires antiarrhythmic medications followed by possible catheter ablation and device (ICD) implantation. Expert commentary: Prospective trials are underway to identify the optimum methods for screening, which will guide future international statements on indications for and methods of screening in CS.

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.

Prognostic role of serial quantitative evaluation of 18F-fluorodeoxyglucose uptake by PET/CT in patients with cardiac sarcoidosis presenting with ventricular tachycardia

BACKGROUND

Positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (FDG) has shown to be useful in diagnosis, staging and monitoring of cardiac sarcoidosis (CS) but its interpretation is not standardized.

OBJECTIVES

We sought to investigate the clinical impact of serial quantitative FDG uptake analysis in patients with CS presenting with ventricular tachycardia (VT) treated by catheter ablation (CA).

METHODS

We followed 20 patients (51 ± 9 years, 70% males) with CS and VT who underwent CA, with 92 serial FDG-PET scans (3-10 per patient). Myocardial FDG-avid lesions were quantified using three parameters: maximum standardized uptake value (SUV_max), partial-volume corrected mean standardized uptake value (SUV_mean) and partial-volume corrected volume-intensity product [lesion metabolic activity (LMA)]. The volume-intensity product of the entire heart [global cardiac metabolic activity (gCMA)] and the background cardiac metabolic activity (bCMA: difference between gCMA and LMA) were also calculated. The primary end-point was the occurrence of major adverse cardiac events (MACE), including death, heart transplant, hospitalization for heart failure and implantable cardioverter defibrillator (ICD) appropriate interventions. Evolution of echocardiographic parameters over follow-up was also assessed.

RESULTS

During a median follow-up of 35 (20-66) months, 18 MACE (1 death, 2 heart transplants, 12 ICD appropriate interventions, 3 hospitalizations) occurred in 12 (60%) patients. At univariable analysis, lack of PET improvement (defined by decrease in LMA of at least 25%) was the only variable associated with cardiac events during follow-up. In particular, non-responders had a 20-fold higher risk of MACE at follow-up (HR 18.96, 95% CI 2.26-159.27; p = 0.007). Moreover, a significant linear inverse relationship was observed between changes in LMA and changes in left ventricular ejection fraction over follow-up (β = -20.11; p = 0.003).

CONCLUSIONS

In patients with CS and VT, temporal change in FDG uptake evaluated by a quantitative approach is associated with parallel change in systolic function. Moreover, reduction in FDG uptake is strongly associated with fewer MACE at long-term follow-up.

Comparative evaluation of 18F-FLT and 18F-FDG for detecting cardiac and extra-cardiac thoracic involvement in patients with newly diagnosed sarcoidosis

Background

¹⁸F-FDG PET has been used in sarcoidosis for diagnosis and determination of the extent of the disease. However, assessing inflammatory lesions in cardiac sarcoidosis using ¹⁸F-FDG can be challenging because it accumulates physiologically in normal myocardium. Another radiotracer, 3′-deoxy-3′-¹⁸F-fluorothymidine (¹⁸F-FLT), has been investigated as a promising PET tracer for evaluating tumor proliferative activity. In contrast to ¹⁸F-FDG, ¹⁸F-FLT uptake in the normal myocardium is low. The purpose of this retrospective study was to compare the uptake of ¹⁸F-FLT and ¹⁸F-FDG in the evaluation of cardiac and extra-cardiac thoracic involvement in patients with newly diagnosed sarcoidosis.

Data for 20 patients with newly diagnosed sarcoidosis were examined. ¹⁸F-FLT and ¹⁸F-FDG PET/CT studies had been performed at 1 h after each radiotracer injection. The patients had fasted for at least 18 h before ¹⁸F-FDG PET/CT but were given no special dietary instructions regarding the period before ¹⁸F-FLT PET/CT. Uptake of ¹⁸F-FLT and ¹⁸F-FDG was examined visually and semiquantitatively using maximal standardized uptake value (SUVmax).

Results

Two patients had cardiac sarcoidosis, 7 had extra-cardiac thoracic sarcoidosis, and 11 had both cardiac and extra-cardiac thoracic sarcoidosis. On visual analysis for diagnosis of cardiac sarcoidosis, 4/20 ¹⁸F-FDG scans were rated as inconclusive because the ¹⁸F-FDG pattern was diffuse, whereas no FLT scans were rated as inconclusive. The sensitivity of ¹⁸F-FDG PET/CT for detection of cardiac sarcoidosis was 85%; specificity, 100%; and accuracy, 90%. The corresponding values for ¹⁸F-FLT PET/CT were 92, 100, and 95%, respectively. Using semiquantitative analysis of cardiac sarcoidosis, the mean ¹⁸F-FDG SUVmax was significantly higher than the mean ¹⁸F-FLT SUVmax (P < 0.005). Both ¹⁸F-FDG and ¹⁸F-FLT PET/CT studies detected all 24 extra-cardiac lesions. Using semiquantitative analysis of extra-cardiac sarcoidosis, the mean ¹⁸F-FDG SUVmax was significantly higher than the mean ¹⁸F-FLT SUVmax (P < 0.001).

Conclusions

The results of this preliminary study suggest that ¹⁸F-FLT PET/CT can detect cardiac and extra-cardiac thoracic involvement in patients with newly diagnosed sarcoidosis as well as ¹⁸F-FDG PET/CT, although uptake of ¹⁸F-FLT in lesions was significantly lower than that of ¹⁸F-FDG. However, ¹⁸F-FLT PET/CT may be easier to perform since it requires neither prolonged fasting nor a special diet prior to imaging.

Semi-quantitative metabolic values on FDG PET/CT including extracardiac sites of disease as a predictor of treatment course in patients with cardiac sarcoidosis

Background

Cardiac sarcoidosis is associated with major adverse cardiac events including cardiac arrest, for which anti-inflammatory treatment is indicated. Oral corticosteroid is the mainstay among treatment options; however, adverse effects are a major concern with long-term use. It would be beneficial for providers to predict treatment response and prognosis for proper management strategy of sarcoidosis, though it remains challenging. Fluorine (F)-18 fluorodeoxyglucose (FDG)-positron emission tomography(PET)/computed tomography(CT) has an advantage over anatomical imaging in providing semi-quantitative functional parameters such as standard uptake value (SUV), metabolic volume, and total lesion glycolysis (TLG), which are well-established biomarkers in oncology. However, the relationship between these parameters and treatment response has not been fully investigated in cardiac sarcoidosis. Also, the prognostic value of extracardiac active inflammation noted on FDG-PET/CT in the setting of cardiac sarcoidosis is unclear. The aim of this retrospective study was to investigate the prognostic value of semi-quantitative values of both cardiac and extracardiac disease sites derived from FDG-PET/CT in predicting treatment course in cardiac sarcoidosis.

Methods

Sixteen consecutive patients with suspected cardiac sarcoidosis, who demonstrated abnormal myocardial activity on cardiac-inflammation FDG-PET/CT encompassing the entire chest/upper abdomen and subsequently underwent corticosteroid therapy for diagnosis of active cardiac sarcoidosis, were included. Semi-quantitative values of hypermetabolic lesions were derived from all visualized organ system and were compared to daily corticosteroid dose at 6 months.

Results

 Of the 16 patients, 81.3% (13/16) of the patients showed extracardiac involvement. The lesion with the greatest SUV was identified in the heart in 11 patients (68.7%), in the liver in 1 patient (6.3%), and in lymph nodes in 4 patients (25%). The maximum SUV across all visualized organ systems including the heart were 8.8 ± 3.1 for the patients with corticosteroid dose ≤ 10 mg and 12.5 ± 3.3 for those with > 10 mg (P = 0.04). Metabolic volume and TLG across all visualized organ systems or any values in the heart alone showed no significant statistical difference between the two groups.

Conclusions

Maximum SUV across all involved organ-systems of the chest and upper abdomen, not that of the heart alone, could be a predictor of treatment course of steroid therapy at 6 months in patients with active cardiac sarcoidosis.

Impact of tissue photon attenuation in small animal cardiac PET imaging

OBJECTIVES

Tissue photon attenuation is one of the essential artifacts requiring correction in clinical cardiac positron emission tomography (PET) imaging. However, due to small body size its impact on diagnostic accuracy in small rodents is considered to be limited or even ignorable. The present cardiac PET study compares lean and obese rats to determine the influence of tissue attenuation on quantitative assessment as well as regional tracer distribution.

METHODS

A dedicated small animal PET system equipped with a ⁵⁷Co rotating source for transmission was used. To assess the impact of tissue attenuation in rats with different body sizes, cardiac ¹⁸F-FDG -PET studies for Zucker diabetic fatty rats (obese rats) and Zucker lean rats (lean rats) were performed. The radiotracer activity reduction by attenuation was compared between the two groups. Regional tracer distribution calculated with and without attenuation correction was also assessed.

RESULTS

The chest diameter was significantly longer in obese than in lean rats (5.6±0.3cm in obese and 4.5±0.2cm in lean rats, p<0.0001). Whereas the activity reduction by attenuation was significantly greater in obese than in lean rats (44.1±2.5% and 5.1±3.1%, p<0.0001), the regional variation of tissue attenuation among the ventricular walls was minimal in both lean (p=0.73) and obese rats (p=0.65).

CONCLUSION

Attenuation correction is indispensable for accurate comparison of cardiac tracer activity between animals with different body size, whereas it can be omitted for evaluation of regional tracer distribution.

Somatostatin receptor based PET/CT in patients with the suspicion of cardiac sarcoidosis: an initial comparison to cardiac MRI

Diagnosis of cardiac sarcoidosis is often challenging. Whereas cardiac magnetic resonance imaging (CMR) and positron emission tomography/computed tomography (PET/CT) with 18F-fluorodeoxyglucose (FDG) are most commonly used to evaluate patients, PET/CT using radiolabeled somatostatin receptor (SSTR) ligands for visualization of inflammation might represent a more specific alternative. This study aimed to investigate the feasibility of SSTR-PET/CT for detecting cardiac sarcoidosis in comparison to CMR.15 patients (6 males, 9 females) with sarcoidosis and suspicion on cardiac involvement underwent SSTR-PET/CT imaging and CMR. Images were visually scored. The AHA 17-segment model of the left myocardium was used for localization and comparison of inflamed myocardium for both imaging modalities. In semi-quantitative analysis, mean (SUVmean) and maximum standardized uptake values (SUVmax) of affected myocardium were calculated and compared with both remote myocardium and left ventricular (LV) cavity.SSTR-PET was positive in 7/15, CMR in 10/15 patients. Of the 3 CMR+/PET- subjects, one patient with minor involvement (<25% of wall thickness in CMR) was missed by PET. The remaining two CMR+/PET- patients displayed no adverse cardiac events during follow-up.In the 17-segment model, PET/CT yielded 27 and CMR 29 positive segments. Overall concordance of the 2 modalities was 96.1% (245/255 segments analyzed). SUVmean and SUVmax in inflamed areas were 2.0±1.2 and 2.6±1.2, respectively. The lesion-to-remote myocardium and lesion-to-LV cavity ratios were 1.8±0.2 and 1.9±0.2 for SUVmean and 2.0±0.3 and 1.7±0.3 for SUVmax, respectively.Detection of cardiac sarcoidosis by SSTR-PET/CT is feasible. Our data warrant further analysis in larger prospective series.

Regional myocardial damage and active inflammation in patients with cardiac sarcoidosis detected by non-invasive multi-modal imaging

AIMS

Cardiac sarcoidosis (CS) can be diagnosed using ¹⁸F-FDG-PET/CT (PET), cardiovascular magnetic resonance (CMR), and ¹²³I-BMIPP/²⁰¹TlCl dual myocardial SPECT. This study aims to clarify the relationships among the three modalities with respect to CS.

METHODS AND RESULTS

We evaluated 16 patients (male n = 11; age 55 ± 13 years) with confirmed CS who underwent PET, CMR, and dual SPECT with gated SPECT before starting steroid therapy. The left ventricular myocardium was divided into 17 segments to obtain SUVmax for PET images, defect scores from 0 to 4 (0 normal; 4 absent), and mismatch scores for dual SPECT (BMDS, TLDS, and MS) images and late gadolinium enhancement (LGE) scores (0 none; 1 partly positive; 2 homogeneous) on CMR images. Summed BMDS, TLDS, and MS were 18.6 ± 12.6, 12.9 ± 10.9, and 5.7 ± 3.1, respectively. The segmental BMDS and TLDS scores became significantly higher as the LGE scores increased. The MS scores were significantly higher in areas of LGE with a score of 1 than 0 (both, p < 0.001), but did not significantly differ between areas with LGE scores of 1 and 2. The SUVmax was significantly higher in LGE areas with a score of 1 than 0 (p < 0.025), but did not significantly differ between those with scores of 1 or 2.

CONCLUSION

Regions with a higher SUVmax indicating active myocardial inflammation were mainly located in areas with LGE, where BMIPP and TL mismatches were evident in patients with CS.

Prognostic Value of Myocardial Scarring on CMR in Patients With Cardiac Sarcoidosis

OBJECTIVES

This study sought to perform a systematic review and meta-analysis to understand the prognostic value of myocardial scarring as evidenced by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging in patients with known or suspected cardiac sarcoidosis.

BACKGROUND

Although CMR is increasingly used for the diagnosis of cardiac sarcoidosis, the prognostic value of CMR has been less well described in this population.

METHODS

PubMed, Cochrane CENTRAL, and metaRegister of Controlled Trials were searched for CMR studies with ≥1 year of prognostic data. Primary endpoints were all-cause mortality and a composite outcome of arrhythmogenic events (ventricular arrhythmia, implantable cardioverter-defibrillator shock, sudden cardiac death) plus all-cause mortality during follow-up. Summary effect estimates were generated with random-effects modeling.

RESULTS

Ten studies were included, involving a total of 760 patients with a mean follow-up of 3.0 ± 1.1 years. Patients had a mean age of 53 years, 41% were male, 95.3% had known extracardiac sarcoidosis, and 21.6% had known cardiac sarcoidosis. The average ejection fraction was 57.8 ± 9.1%. Patients with LGE had higher odds for all-cause mortality (odds ratio [OR]: 3.06; p < 0.03) and higher odds of the composite outcome (OR: 10.74; p < 0.00001) than those without LGE. Patients with LGE had an increased annualized event rate of the composite outcome (11.9% vs. 1.1%; p < 0.0001).

CONCLUSIONS

In patients with known or suspected cardiac sarcoidosis, the presence of LGE on CMR imaging is associated with increased odds of both all-cause mortality and arrhythmogenic events.

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

Background

Cardiac sarcoidosis (CS) is a potentially fatal condition lacking a single test with acceptable diagnostic accuracy. ¹⁸F-FDG PET/CT has emerged as a promising imaging modality, but is challenged by physiological myocardial glucose uptake. An alternative tracer, ⁶⁸Ga-DOTANOC, binds to somatostatin receptors on inflammatory cells in sarcoid granulomas. We therefore aimed to conduct a proof-of-concept study using ⁶⁸Ga-DOTANOC to diagnose CS. In addition, we compared diagnostic accuracy and inter-observer variability of ⁶⁸Ga-DOTANOC vs. ¹⁸F-FDG PET/CT.

Methods

Nineteen patients (seven female) with suspected CS were prospectively recruited and dual tracer scanned within 7 days. PET images were reviewed by four expert readers for signs of CS and compared to the reference standard (Japanese ministry of Health and Welfare CS criteria).

Results

CS was diagnosed in 3/19 patients. By consensus, 11/19 ¹⁸F-FDG scans and 0/19 ⁶⁸Ga-DOTANOC scans were rated as inconclusive. The sensitivity of ¹⁸F-FDG PET for diagnosing CS was 33 %, specificity was 88 %, PPV was 33 %, NPV was 88 %, and diagnostic accuracy was 79 %. For ⁶⁸Ga-DOTANOC, accuracy was 100 %. Inter-observer agreement was poor for ¹⁸F-FDG PET (Fleiss’ combined kappa 0.27, NS) and significantly better for ⁶⁸Ga-DOTANOC (Fleiss’ combined kappa 0.46, p = 0.001).

Conclusions

Despite prolonged pre-scan fasting, a large proportion of ¹⁸F-FDG PET/CT images were rated as inconclusive, resulting in low agreement among reviewers and correspondingly poor diagnostic accuracy. By contrast, ⁶⁸Ga-DOTANOC PET/CT had excellent diagnostic accuracy with the caveat that inter-observer variability was still significant. Nevertheless, ⁶⁸Ga-DOTANOC PET/CT looks very promising as an alternative CS PET tracer.

Trial registration

Current Controlled Trials NCT01729169.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-016-0207-6) contains supplementary material, which is available to authorized users.

Cardiovascular PET-CT imaging: a new frontier?

Cardiovascular positron-emission tomography combined with computed tomography (PET-CT) has recently emerged as an imaging technology with the potential to simultaneously describe both anatomical structures and physiological processes in vivo. The scope for clinical application of this technique is vast, but to date this promise has not been realised. Nonetheless, significant research activity is underway to explore these possibilities and it is likely that the knowledge gained will have important diagnostic and therapeutic implications in due course. This review provides a brief overview of the current state of cardiovascular PET-CT and the likely direction of future developments.