The utility of PET/CT with (68)Ga-DOTATOC in sarcoidosis: comparison with (67)Ga-scintigraphy

177 Lu-DOTATATE Uptake in the Lungs of a Patient With COVID-19 Pneumonia

ABSTRACT

A 76-year-old woman with liver and bone metastasis of a duodenal neuroendocrine tumor received peptide receptor radionuclide therapy with 177 Lu-DOTATATE. Scintigraphy with SPECT/CT performed 4 days after the treatment demonstrated 177 Lu-DOTATATE uptake as multifocal ground glass opacities in the bilateral lungs. This uptake was considered to be due to COVID-19 pneumonia because the patient was infected with the virus 7 days prior to the treatment. The lung opacities became smaller, showing a decreased uptake, 2 months later, after the second treatment. 177 Lu-DOTATATE may be taken up during the active phase of COVID-19 pneumonia.

Th17.1 cell driven sarcoidosis-like inflammation after anti-BCMA CAR T cells in multiple myeloma

Pseudo-progression and flare-up phenomena constitute a novel diagnostic challenge in the follow-up of patients treated with immune-oncology drugs. We present a case study on pulmonary flare-up after Idecabtagen Vicleucel (Ide-cel), a BCMA targeting CAR T-cell therapy, and used single-cell RNA-seq (scRNA-seq) to identify a Th17.1 driven autoimmune mechanism as the biological underpinning of this phenomenon. By integrating datasets of various lung pathological conditions, we revealed transcriptomic similarities between post CAR T pulmonary lesions and sarcoidosis. Furthermore, we explored a noninvasive PET based diagnostic approach and showed that tracers binding to CXCR4 complement FDG PET imaging in this setting, allowing discrimination between immune-mediated changes and true relapse after CAR T-cell treatment. In conclusion, our study highlights a Th17.1 driven autoimmune phenomenon after CAR T, which may be misinterpreted as disease relapse, and that imaging with multiple PET tracers and scRNA-seq could help in this diagnostic dilemma.

FDG PET/CT Imaging of Sarcoidosis

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

Gallium-68 Labelled Radiopharmaceuticals for Imaging Inflammatory Disorders

Inflammation is an important component of several chronic and debilitating diseases that result in significant morbidity and mortality. This is best evidenced within the cardiovascular system where it may manifest as atherosclerosis or myocarditis, and at the extreme end of the spectrum as myocardial infarction, ventricular remodeling, or cardiac failure. Early non-invasive detection and monitoring of inflammation in these and other settings may better guide patient management with resultant improved outcomes. Key role players in inflammation pathophysiology include chemokines, macrophages, neutrophils, fibroblasts, integrins, and reactive oxygen species, amongst others. Examples of receptor expression and over-expression include somatostatin receptors, CXCR4-, folate-, mannose-, TSPO- receptors and secretion of various vascular adhesion molecules (such as VCAM and ICAM). Gallium-68-based PET offers imaging possibilities for nearly all the major pathophysiological role players in inflammation, with mounting recent interest in macrophage differentiation, various forms of receptor expression and secretion of chemokines and vascular adhesion molecules. The advantages in terms of logistics and costs of having generator-produced PET probes available is well known, and a ⁶⁸Ga-based tracer provides easily translatable theranostic possibilities to especially Lu-177. Some of the more versatile and better validated Ga-68-based inflammation probes include ⁶⁸Ga-DOTA-TATE/NOC/TOC, ⁶⁸Ga-NOTA-RGD, ⁶⁸Ga-CXCR4, ⁶⁸Ga-citrate and ⁶⁸Ga-FAPI.

Radionuclide Assessment of Sarcoidosis

This review provides an overview of the techniques used in nuclear cardiology for the assessment of suspected or known cardiac sarcoidosis, how radionuclide imaging assists with regard to diagnosis, risk stratification, and monitoring response to therapy, and work that is on the horizon with novel tracers.

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.

Radiotracers to Address Unmet Clinical Needs in Cardiovascular Imaging, Part 2: Inflammation, Fibrosis, Thrombosis, Calcification, and Amyloidosis Imaging

Cardiovascular imaging is evolving in response to systemwide trends toward molecular characterization and personalized therapies. The development of new radiotracers for PET and SPECT imaging is central to addressing the numerous unmet diagnostic needs that relate to these changes. In this 2-part review, we discuss select radiotracers that may help address key unmet clinical diagnostic needs in cardiovascular medicine. Part 1 examined key technical considerations pertaining to cardiovascular radiotracer development and reviewed emerging radiotracers for perfusion and neuronal imaging. Part 2 covers radiotracers for imaging cardiovascular inflammation, thrombosis, fibrosis, calcification, and amyloidosis. These radiotracers have the potential to address several unmet needs related to the risk stratification of atheroma, detection of thrombi, and the diagnosis, characterization, and risk stratification of cardiomyopathies. In the first section, we discuss radiotracers targeting various aspects of inflammatory responses in pathologies such as myocardial infarction, myocarditis, sarcoidosis, atherosclerosis, and vasculitis. In a subsequent section, we discuss radiotracers for the detection of systemic and device-related thrombi, such as those targeting fibrin (e.g., ⁶⁴Cu-labeled fibrin-binding probe 8). We also cover emerging radiotracers for the imaging of cardiovascular fibrosis, such as those targeting fibroblast activation protein (e.g., ⁶⁸Ga-fibroblast activation protein inhibitor). Lastly, we briefly review radiotracers for imaging of cardiovascular calcification (¹⁸F-NaF) and amyloidosis (e.g., ^99mTc-pyrophosphate and ¹⁸F-florbetapir).

Nonmalignant Thoracic Disorders: An Appraisal of Fluorodeoxyglucose and Non-fluorodeoxyglucose PET/Computed Tomography Applications

PET/computed tomography (CT) with fluorodeoxyglucose and nonfluorodeoxyglucose PET tracers has established itself in the management of malignant disorders. Its role in the assessment of nonmalignant conditions, such as infectious and noninfectious inflammatory diseases and other benign conditions, has emerged independently and alongside its role being evaluated in malignancy and continues to evolve. It is evident that PET/CT has the potential to play a significant role in various nonmalignant disorders of the thorax. This review highlights current developments and areas where PET/CT has a potential to impact the clinical management of nonmalignant thoracic conditions with special focus on nonfluorodeoxyglucose tracers.

111In-Pentetreotide Uptake Due to COVID-19 Vaccination

ABSTRACT

A 72-year-old woman was referred for whole-body 111In-pentetreotide scintigraphy with SPECT/CT. There was increased uptake of lymphadenopathy in the left axilla and left deltoid muscle. The patient's history revealed that the patient received the first dose of the COVID-19 vaccine 3 days before the 111In-pentetreotide scintigraphy with SPECT/CT. This case demonstrates that the COVID-19 vaccine can cause 111In-pentetreotide uptake in the lymph nodes and the deltoid muscle.

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

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

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.

Emerging Preclinical and Clinical Applications of Theranostics for Nononcological Disorders

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Advanced Nuclear Medicine and Molecular Imaging in the Diagnosis of Cardiomyopathy

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

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.

Infection and Inflammation Imaging: Beyond FDG

This review discusses nuclear imaging of inflammation using molecular probes beyond fluoro-d-glucose, is structured by cellular targets, and focuses on those tracers that have been successfully applied clinically.

Somatostatin receptor imaging by SPECT and PET in patients with chronic inflammatory disorders: a systematic review

OBJECTIVE

To review the literature on the clinical application of radiolabeled somatostatin receptor scintigraphy (SRS) by SPECT and PET in adults with chronic inflammatory diseases.

RESEARCH DESIGN

Systematic review of published observational studies between 1993 and 2017.

DATA COLLECTION AND ANALYSIS

The Cochrane Central Register of Controlled Trials, MedLine, EMBASE, PubMed, Google Scholar, OVID, EBSCO, Scopus, and Web of Science were used to search for studies on the use of SRS in adults with chronic inflammatory diseases. A team of reviewers independently screened for eligible studies. Quality of evidence was assessed by QUADAS approach.

RESULTS

Eligible papers included 38 studies. Studied populations were heterogeneous, and patients were classified according to the diagnosed disease: endothelial inflammation, rheumatoid arthritis, cardiac allograft rejection, granulomatous diseases, small vessel vasculitis, idiopathic pulmonary fibrosis, sarcoidosis, and thyroid exophthalmopathy. Because of many quality differences between studies, it was not possible to pool data, and a narrative synthesis is reported.

CONCLUSION

Results highlight the value of SRS to detect active inflammation in several chronic inflammatory conditions, despite the bias related to the index test, showing lack of standardization of the scintigraphic technique and high variability of methods used to clinically evaluate inflammatory condition.

New advances in the management of pulmonary sarcoidosis

Sarcoidosis is a highly variable granulomatous multisystem syndrome. It affects individuals in the prime years of life; both the frequency and severity of sarcoidosis are greater in economically disadvantaged populations. The diagnosis, assessment, and management of pulmonary sarcoidosis have evolved as new technologies and therapies have been adopted. Transbronchial needle aspiration guided by endobronchial ultrasound has replaced mediastinoscopy in many centers. Advanced imaging modalities, such as fluorodeoxyglucose positron emission tomography scanning, and the widespread availability of magnetic resonance imaging have led to more sensitive assessment of organ involvement and disease activity. Although several new insights about the pathogenesis of sarcoidosis exist, no new therapies have been specifically developed for use in the disease. The current or proposed use of immunosuppressive medications for sarcoidosis has been extrapolated from other disease states; various novel pathways are currently under investigation as therapeutic targets. Coupled with the growing recognition of corticosteroid toxicities for managing sarcoidosis, the use of corticosteroid sparing anti-sarcoidosis medications is likely to increase. Besides treatment of granulomatous inflammation, recognition and management of the non-granulomatous complications of pulmonary sarcoidosis are needed for optimal outcomes in patients with advanced disease.

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

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

Advanced cardiovascular imaging for the evaluation of cardiac sarcoidosis

Cardiac sarcoidosis (CS) remains an intriguing infiltrating disorder and one of the most important forms of inflammatory cardiomyopathy. Identification of patients with CS is of extreme importance because they are at higher risk of sudden death, and heart-failure progression. And while it remains a diagnostic conundrum, a great amount of experience has been accumulated over the last decade with the advent of fluorine-18 fluorodeoxyglucose positron emission tomography and cardiac magnetic resonance with late gadolinium enhancement imaging. They have both proven to be advanced imaging techniques that provide important, and often complementary, diagnostic and prognostic information for the management of CS. However, they have also shown to have limitations, and, thus, there is a continued need for developing more specific imaging probes for identifying cardiac inflammation. The aim of the present manuscript is to provide the reader with a better understanding of the histopathology of the disease, how this potentially relates to noninvasive imaging detection, and the best strategies available for the diagnosis and management of patients with CS.

Gallium-68 DOTA-NOC PET/CT as an alternate predictor of disease activity in sarcoidosis

INTRODUCTION

We evaluated the role of gallium-68-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-octreotide (Ga-DOTA-NOC) PET/CT in assessing sarcoidosis disease activity.

PATIENTS AND METHODS

Patients diagnosed with sarcoidosis underwent Ga-DOTA-NOC-PET/CT. The maximum standardized uptake value (SUVmax) at the pathological site and in the descending thoracic aorta (reference standard, SUVmed) were assessed. A SUVmax/SUVmed ratio (disease activity score) of more than one was considered a marker of active disease and was compared with the clinical symptoms and serum angiotensin-converting enzyme and computed tomography (CT) scan. The primary outcome was to assess the efficacy of the scan in estimating disease activity.

RESULTS

Of the 39 patients enrolled in the study, 27 patients were symptomatic and the rest were asymptomatic at enrollment. Increased disease activity was present in 25 (92%) of the 27 symptomatic patients and two (16%) of the 12 asymptomatic patients. The sensitivity and specificity of the test were 92.5% (95% confidence interval=75.7-99.0) and 83.3% (95% confidence interval=51.5-97.9), respectively. Seven out of nine patients who became asymptomatic after treatment showed a significant decrease in the mean disease activity score in post-treatment scans (3.38±1.05 vs 1.20±0.82, P<0.001).

CONCLUSION

Ga-DOTA-NOC PET/CT emerged as a useful tool to assess the disease activity and treatment response in patients with sarcoidosis with thoracic involvement.

Prospective of 68Ga Radionuclide Contribution to the Development of Imaging Agents for Infection and Inflammation

During the last decade, the utilization of ⁶⁸Ga for the development of imaging agents has increased considerably with the leading position in the oncology. The imaging of infection and inflammation is lagging despite strong unmet medical needs. This review presents the potential routes for the development of ⁶⁸Ga-based agents for the imaging and quantification of infection and inflammation in various diseases and connection of the diagnosis to the treatment for the individualized patient management.

Somatostatin receptor based hybrid imaging in sarcoidosis

Several diagnostic imaging methodologies are available for the clinical evaluation of sarcoidosis, but all have their limitations. FDG PET/CT is frequently used, but this technique does not provide optimal results in all cases. Novel radiopharmaceuticals aimed at other disease targets may be helpful, particularly in cardiac sarcoidosis when FDG PET/CT has a low diagnostic accuracy, due to difficulties in preparing the patients who should use a specific diet combined with prolonged fasting. ⁶⁸Ga-labeled somatostatin based receptor hybrid imaging is a potential alternative to FDG PET/CT.

This short communication provides a rapid overview of initial findings concerning the application of ⁶⁸Ga-labeled somatostatin based receptor hybrid imaging in the diagnosis of (cardiac) sarcoidosis activity.