Identification and characterization of myocardial metastases in neuroendocrine tumor patients using 68Ga-DOTATATE PET-CT

Cardiac Neuroendocrine Tumor Metastases on 68Ga-DOTATATE PET/CT: Identification and Prognostic Significance

Neuroendocrine tumor (NET) metastases to the heart are found in 1%-4% of NET patients and have been reported primarily in the form of individual cases. We investigated the prevalence, clinical characteristics, imaging features, and outcomes of NET patients with cardiac metastases on 68Ga-DOTATATE PET/CT. Methods: 68Ga-DOTATATE PET/CT of 490 consecutive patients from a single institution were retrospectively reviewed for sites of metastases. The cumulative cardiovascular event rate and overall survival of patients with cardiac NET metastases (CNMs) were compared with those of a control group of metastatic NET patients without cardiac metastases. In patients with CNMs, the cardiac SUVmax with and without normalization to the myocardial background uptake was compared with a separate cohort of 11 patients with active cardiac sarcoidosis who underwent 68Ga-DOTATATE PET/CT for research purposes. Results: In total, 270 patients with metastatic NETs were identified, 9 (3.3%) of whom had CNMs. All 9 patients had grade 1-2 gastroenteropancreatic NETs, most commonly from the small intestine (7 patients). The control group consisted of 140 patients with metastatic grade 1-2 gastroenteropancreatic NETs. On Kaplan-Meier analysis, there was no significant difference in the risk of cardiovascular adverse events (P = 0.91 on log-rank test) or mortality (P = 0.83) between the metastatic NET patients with and without cardiac metastases. The degree of cardiac DOTATATE uptake was significantly higher in CNMs than in patients with cardiac sarcoidosis without overlap, in terms of both cardiac SUVmax (P = 0.027) and SUVmax-to-myocardial background ratio (P = 0.021). Conclusion: Routine 68Ga-DOTATATE PET/CT can be used to identify CNMs in 3% of patients with metastatic NETs. CNMs do not confer added cardiovascular or mortality risk. A distinguishing feature of CNMs is their high degree of DOTATATE uptake compared with focal myocardial inflammation.

A Neuroendocrine Tumor of Unknown Primary Origin: A Case Report and Review of the Literature

Neuroendocrine tumors (NETs) are uncommon malignancies that develop from neuroendocrine cells which most commonly occur in the GI tract, lung, and pancreas. Treatment courses for these tumors are largely dictated by the primary origin site, which can present diagnostic and therapeutic challenges in NETs of unknown primary origin. Herein, we present a case of an NET of unknown primary origin with significant liver metastases. Our aim is to highlight the key components of the workup of NETs of unknown primary origin and detail the biochemical, histopathological, and imaging modalities as recommended by current literature. We highlight the importance of a multidisciplinary approach to both diagnosis and treatment of these patients as well as touch upon therapeutic options.

Myocardial, Retro-orbital, and Bilateral Testicular Metastases of an Ileal Neuroendocrine Tumor in 68 Ga-DOTATATE PET/CT

ABSTRACT

A 71-year-old man with a newly discovered metastatic grade II neuroendocrine tumor of the terminal ileum was referred for a 68 Ga-DOTATATE PET/CT scan to stage the disease and assess suitability for PRRT (peptide receptor radionuclide therapy). The patient was known to have secondary nodal and bone/liver metastatic disease through prior morphological investigations. PET images revealed an atypical pattern of metastatic disease, showcasing secondary lesions in bilateral extraocular muscles, the myocardium, and both testes. The patient was pauci-symptomatic and only reported fatigue and diarrhea. Management involved lanreotide administration, and PRRT is being envisaged.

H3 Derivatives Possessing Picolyl and Picolinate Pendants for Ga3+ Coordination and 67Ga3+ Radiolabeling

We synthesized, thanks to the regiospecific N-functionalization using an orthoamide intermediate, two 1,4,7-triazacyclononane derivatives containing an acetate arm and either a methylpyridine or a picolinic acid group, respectively, Hnoapy and H2noapa, as new Ga3+ chelators for potential use in nuclear medicine. The corresponding Ga3+ complexes were synthesized and structurally characterized in solution by 1H and 13C NMR. The [Ga(noapy)]2+ complex appears to exist in solution as two diasteroisomeric pairs of enantiomers, as confirmed by density functional theory (DFT) calculations, while for [Ga(noapa)]+, a single species is present in solution. Solid-state investigations were possible for the [Ga(noapa)]+ complex, which crystallized from water as a pair of enantiomers. The average length of the N-Ga bonds of 2.090 Å is identical with that found for the [Ga(nota)] complex, showing that the presence of the picolinate arm does not hinder the coordination of the ligand to the metal ion. Protonation constants of noapy- and noapa2- were determined by potentiometric titrations, providing an overall basicity ∑log KiH (i = 1-4) that increases in the order noapy- < noapa2- < nota3- with increases in the negative charge of the ligand. Stability constants determined by pH-potentiometric titrations supplemented with 71Ga NMR data show that the stabilities of [Ga(noapy)]2+ and [Ga(noapa)]+ are lower compared to that of [Ga(nota)] but higher than those of other standards such as [Ga(aazta)]-. 67Ga radiolabeling studies were performed in order to demonstrate the potential of these chelators for 67/68Ga-based radiopharmaceuticals. The labelings of Hnoapy and H2noapa were nearly identical, outperforming H3nota. Stability studies were conducted in phosphate-buffered saline and in the presence of human serum transferrin, revealing no significant decomplexation of [67Ga][Ga(noapy)]2+ and [67Ga][Ga(noapa)]+ compared to [67Ga][Ga(nota)]. Finally, all complexes were found to be highly hydrophilic, with calculated log D7.4 values of -3.42 ± 0.05, -3.34 ± 0.04, and -3.00 ± 0.23 for Hnoapy, H2noapa, and H3nota, respectively, correlating with the charge of each complex and the electrostatic potentials obtained with DFT.

Cardiac metastases from neuroendocrine neoplasms: complementary role of SSTR PET/CT and cardiac MRI

BACKGROUND

Cardiac metastases from neuroendocrine neoplasms (NENs) are being detected with increasing frequency, although the optimal imaging strategy remains unclear. We performed a single-center retrospective study to explore the role of somatostatin receptor positron emission tomography/computed tomography (SSTR PET/CT) and cardiac magnetic resonance imaging (CMR) in NEN cardiac metastases, determine the degree of concordance between the findings of these imaging modalities, and examine the advantages and disadvantages of each imaging technique. A secondary aim was to determine if cardiac metastases were associated with adverse cardiac events during peptide receptor radionuclide therapy (PRRT).

METHODS AND RESULTS

19 patients with NEN cardiac metastases were identified. A retrospective review of electronic medical records was performed, and if available SSTR PET/CT and CMR were blindly re-reviewed by imaging specialists, documenting the number and location of cardiac metastases. All 19 patients had SSTR PET/CT, and 10/19 patients had CMR. SSTR PET/CT identified more metastases than CMR. When identified on CMR, metastases were more accurately localized. 12/19 patients received PRRT, with no cardiac adverse effects.

CONCLUSION

SSTR PET/CT and CMR are complementary investigations in the imaging of NEN cardiac metastases. SSTR PET/CT appears more sensitive for lesion detection, and CMR offers better lesion characterization. Both investigations present useful information for the planning of treatment including PRRT, which was administered safely.

Gastroenteropancreatic Neuroendocrine Tumor Metastasis to the Heart: Evaluation of Imaging Manifestations

Neuroendocrine tumors (NET) may affect the heart by cardiac metastasis or carcinoid heart disease. NET metastasis to the heart is rare, with limited data characterizing it. We sought to evaluate 68Ga-DOTATATE PET scan imaging features and associated cardiac imaging characteristics where available in those with NET cardiac metastases. 68Ga-DOTATATE positron emission tomography (PET)/CT scans performed on patients with gastroenteropancreatic (GEP) NET at our institution were reviewed for cardiac involvement. Those identified with cardiac metastases had their electronic medical record, transthoracic echocardiogram (TTE) and cardiac magnetic resonance imaging (MRI) reviewed for characterization. From a total of 1426 68Ga-DOTATATE PET/CT scans performed on patients with GEP-NET, 25 (1.75%) had cardiac uptake consistent with metastasis. Of these, 22 had myocardial metastases (29 distinct myocardial lesions: left ventricle - 16, right ventricle - 6, and ventricular septum -7) and 3 had periradial lymph node involvement only. NET patients with cardiac metastases as identified by DOTATATE scan did not appear to have any hemodynamically significant TTE features, aside from those (2/25) who had concomitant carcinoid heart disease. Of the 14 patients who had available TTE for review, only one with high metastatic cardiac tumor burden had detectable cardiac mass. Of the 6 cases who had available MRI, all had metastatic cardiac lesions seen with excellent correlation with tumor localization on 68Ga-DOTATATE PET scan. 68Ga-DOTATATE PET has excellent capability for the diagnosis of cardiac NET metastasis. Cardiac MRI may provide further anatomic and tissue characterization evaluation. Those with myocardial NET metastases without carcinoid heart disease did not have significant hemodynamic effect based on echocardiographic criteria.

A Systematic Review and Meta-Analysis of Prevalence and Outcomes of Cardiac Metastasis of Neuroendocrine Malignancies

Neuroendocrine tumors (NETs) are a rare group of malignancies which are aggressive and widely metastatic. Cardiac metastases (CMs) are rarely reported because of NET. We aim to analyze the available literature to study the proportional prevalence of CM because of NET and its location and effect on the ejection fraction (EF) and survival rate. Our search strategy and meta-analysis are in line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) AMSTAR-2 (Assessing the methodological quality of systematic Reviews-2) Guidelines. A literature search was conducted on MEDLINE (EMBASE and PubMed) for randomized clinical trials, pilot trials, and retrospective and prospective studies. Statistical analysis was performed using the CRAN-R software (https://CRAN.R-project.org/doc/FAQ/R-FAQ.html). The quality assessment of the included articles was performed using the Cochrane Risk of Bias and Newcastle-Ottawa Scale. A total of 16,685 patients were included in the study. The mean age of patients included in the study was 61.28 ± SD 9.89 years. Of these, 257 patients had a total of 283 CM. Metastasis was mainly located in the left ventricle with a pooled proportion of 0.48, 95% confidence interval (CI) 0.4 to 0.56, pericardium: 0.34, 95% CI 0.19 to 0.53, right ventricle 0.28, 95% CI 0.16 to 0.44, interventricular septum 0.25, 95% CI 0.16 to 0.37, left atrium 0.1, 95% CI 0.03 to 0.26 and right atrium 0.05, 95% CI 0.01 to 0.20. Decrease in EF at the time of CM diagnosis was the effect most consistently reported in patients with CM. Pooled mean survival was 35.89, 95% CI 8.27 to 155.68 months after the diagnosis of CM. CM due to NET was <2% and the left ventricle is the most common metastatic location, followed by the pericardium. Decreased EF was the most common clinical picture observed. Further studies are needed to analyze the clinical impact of NET CM.

Hybrid imaging of neuroendocrine tumors in the heart: Union is strength

Cardiac neuroendocrine tumors (NETs) are particularly rare tumors that can lead to a very poor clinical outcome, partly because of metastases but mainly because of manifestations of the hormonal activity they exhibit. Prompt diagnosis is important in order to start the most effective treatment for their removal or management, with the fewest complications. They are often difficult to diagnose, especially in their early stages. One of the reasons for this is that the heart is an organ with a high rate of metabolism and is located in close proximity to other high-metabolism organs. In addition, the anatomic location and their small size render their diagnosis extremely challenging. In recent years, hybrid imaging methods have revolutionized the diagnostic approach to oncology patients and have established a place in the diagnosis of cardiac NETs, because they provide both anatomical and functional information at the same time. Positron emission tomography/computed tomography (PET/CT), PET/magnetic resonance imaging (PET/MRI) and single-photon emission computed tomography/CT (SPECT/CT) are widely used in clinical practice because of the very important metabolic information, the high sensitivity and specificity. However, prospective studies are needed to confirm the true clinical and prognostic value of various hybrid imaging diagnostic techniques in cardiac NETs.

Diagnostic test accuracies of F-18 FDG PET for characterisation of cardiac masses compared to conventional imaging techniques: systematic review and meta-analysis

OBJECTIVE

The present systematic review and meta-analysis compared the diagnostic performance of F-18 fludeoxyglucose positron emission tomography (18F-FDG PET) and conventional imaging, including MRI, echocardiography, and CT, in characterising cardiac masses.

METHODS

A literature search of the PubMed, Cochrane, and EMBASE databases for studies comparing the diagnostic accuracies of 18F-FDG PET and conventional imaging in characterising cardiac masses, from inception of indexing to 31 July 2020, was performed. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess study quality. Sensitivity and specificity across the studies were determined, positive and negative likelihood ratios (LR+ and LR-, respectively) were calculated, and summary receiver operating characteristic curves were constructed.

RESULTS

Of six included studies (n = 212 patients), 18F-FDG PET demonstrated a pooled sensitivity of 0.89 (95% confidence interval [CI] 0.81-0.94) and a pooled specificity of 0.89 (95% CI 0.80-0.94). LR syntheses yielded an overall LR+ of 7.9 (95% CI 4.3-14.6) and LR- of 0.12 (95% CI 0.07-0.22). The calculated pooled diagnostic odds ratio (DOR) was 64 (95% CI 23-181). For conventional imaging, the pooled sensitivity was 0.70 (95% CI 0.57-0.81) and the pooled specificity was 0.96 (95% CI 0.88-0.98). LR syntheses yielded an overall LR+ of 16.1 (95% CI 5.8-44.5) and LR- of 0.31 (95% CI 0.21-0.46). The evaluated pooled DOR was 52 (95% CI 17-155).

CONCLUSION

18F-FDG PET and conventional imaging demonstrated comparable diagnostic accuracies for the characterisation of cardiac masses. Further large multicentre studies are, however, required to corroborate the diagnostic performances of 18F-FDG PET and conventional imaging for the characterisation of cardiac masses.

ADVANCES IN KNOWLEDGE

No previous studies have comprehensively analysed the diagnostic performance of 18F-FDG PET/CT compared with conventional imaging techniques including echocardiography, CT, and MRI. According to the current study, 18F-FDG PET/CT yielded a pooled DOR of 64, whereas other conventional imaging techniques demonstrated a DOR of 52. As such, 18F-FDG PET/CT demonstrated sensitivity and specificity, with a high pooled DOR comparable with other conventional imaging modalities.

Rare case of concurrent suprasternal and cardiac metastasis from small bowel neuroendocrine tumour

Neuroendocrine tumours (NETs) are rare tumours derived from the neuroendocrine cell system, arising across a wide range of organs, most commonly the gastrointestinal tract and bronchopulmonary symptoms. Although NETs can metastasis widely throughout the body, cardiac metastasis is rare with an incidence of 2–4% and usually presents in the presence of extensive metastasis elsewhere. Suprasternal metastasis to the neck is exceedingly rare with <20 cases reported in the literature. We report the case of a 71-year-old female with concurrent cardiac and suprasternal metastasis at diagnosis of terminal ileal NET.

Incidental cardiac findings on somatostatin receptor PET/CT: What do they indicate and are they of clinical relevance?

We present the case of a 47-year-old man with a history of recurrent episodes of frontal headache, fever, and chest discomfort as well as longstanding, difficult to treat arterial hypertension. Clinical work-up revealed the unexpected finding of an underlying pheochromocytoma as well as recent "silent" myocardial infarction. Our case highlights the importance of paying attention to incidental cardiac findings on somatostatin receptor positron emission tomography/computed tomography, as routinely performed in patients with clinically suspected neuroendocrine tumors. These incidental cardiac findings cannot only indicate a primary or secondary (metastatic) neuroendocrine tumor, but also areas of myocardial inflammation, as somatostatin receptors cannot only be found on the majority of neuroendocrine tumors, but also among other tissues on the surface of activated macrophages and lymphocytes. The detection of myocardial inflammation is of clinical importance and its underlying etiology should be evaluated to prompt eventual necessary treatment, as it is a potential driving force for cardiac remodeling and poor prognosis.

The Use of Peptide Receptor Radionuclide Therapy in Patients With Neuroendocrine Tumor Cardiac Metastases

Cardiac metastases are an infrequent site of metastasis in neuroendocrine tumors, and the treatment implications in the era of peptide receptor radionuclide therapy (PRRT) are unclear. Potential safety concerns exist regarding cardiac integrity and function in response to PRRT. We describe our institutional experience with 4 patients with well-differentiated, midgut neuroendocrine tumors with cardiac involvement detected on Ga-DOTATATE PET/CT scans who were treated with PRRT.

Cardiac Metastases in Patients with Neuroendocrine Tumours: Clinical Features, Therapy Outcomes, and Prognostic Implications

BACKGROUND

Cardiac metastases (CM) from neuroendocrine tumours (NET) are rare; however, with the introduction of new molecular imaging modalities, such as 68Ga-DOTATATE PET-CT for NET diagnosis and re-staging, they are now identified more frequently. This study presents a single-institution experience on the NET CM characteristics, management, and prognostic implications.

METHODS

Between January 1998 and January 2020, 25 NET patients with CM were treated in our unit. A retrospective review of electronic records was performed. Overall survival (OS) was assessed by the Kaplan-Meier method. Cox regression models were used to evaluate the association of various clinical variables with OS.

RESULTS

The median age in the NET CM cohort was 64 years, with small intestine being the most common primary (84%). Nearly half of the patients suffered either from shortness of breath (48%) or had palpitations (12%). Peptide receptor radionuclide therapy (PRRT) was applied in more than half of the patients (64%), who had an improved trend for a longer median OS compared to those patients who did not receive PRRT (76.0 vs. 14.0 months, p = 0.196). The multivariate analysis demonstrated that concomitant skeletal or pancreatic metastases, as well as N-terminal pro-B-type natriuretic peptide (NT pro-BNP) >2 × upper limit of normal (ULN), were independent poor prognosticators.

CONCLUSIONS

Clinical features of NET CM ranged from asymptomatic patients to heart failure. Concomitant bone or pancreatic metastases and NT pro-BNP levels >2 ULN predicted shorter survival time. PRRT serves as a feasible therapy with promising survival benefits; however, more data are needed.

Cardiac Metastasis Caused Fatal Ventricular Arrhythmia in a Patient with a Rectal Neuroendocrine Tumor

A 60-year-old man had received octreotide for a metastatic neuroendocrine tumor (NET) in the rectum. Computed tomography and ultrasonography revealed a cardiac tumor, diffuse thickness of the ventricular wall and pericardial effusion, which was diagnosed as cardiac metastasis. The metastatic lesions continued to grow despite the alteration of chemotherapy, and the patient complained of repeated syncope and was admitted to our hospital at 11 months after the diagnosis of cardiac metastasis. An electrocardiogram during syncope showed sustained ventricular tachycardia, which was considered to be caused by the cardiac metastasis. We herein report a case of NET with cardiac metastasis which caused lethal arrhythmia along with a review of the pertinent literature.

Cardiac Metastases in Neuroendocrine Tumors: 68Ga-DOTATATE PET/CT With Cardiac Magnetic Resonance Correlation

Neuroendocrine tumor (NET) cardiac metastases can be associated with complications including ventricular outflow obstruction, arrhythmias, heart failure, and cardiac arrest, warranting intervention. Anatomical characterization of these lesions via cardiac magnetic resonance (CMR) is helpful to assess and predict the risk of complications and guide therapy. Images of 2 patients with small bowel NET related cardiac metastases are described on Ga-DOTATATE PET/CT and CMR. The lesions were significantly smaller and more obscure on CMR compared with PET/CT. On CMR, T2-weighted dark blood images and late gadolinium enhancement images offered the most conspicuous detection of the NET myocardial metastases in these cases.