FDG PET/CT Imaging of Sarcoidosis

PET/CT Imaging of Infectious Diseases: Overview of Novel Radiopharmaceuticals

Infectious diseases represent one of the most common causes of hospital admission worldwide. The diagnostic work-up requires a complex clinical approach, including laboratory data, CT and MRI, other imaging tools, and microbiologic cultures. PET/CT with 18F-FDG can support the clinical diagnosis, allowing visualization of increased glucose metabolism in activated macrophages and monocytes; this tracer presents limits in differentiating between aseptic inflammation and infection. Novel PET radiopharmaceuticals have been developed to overcome these limits; 11C/18F-labeled bacterial agents, several 68Ga-labeled molecules, and white blood cells labeled with 18F-FDG are emerging PET tracers under study, showing interesting preliminary results. The best choice among these tracers can be unclear. This overview aims to discuss the most common diagnostic applications of 18F-FDG PET/CT in infectious diseases and, as a counterpoint, to describe and debate the advantages and peculiarities of the latest PET radiopharmaceuticals in the field of infectious diseases, which will probably improve the diagnosis and prognostic stratification of patients with active infectious diseases.

Diagnostic Value of Imaging and Serological Biomarkers in Pulmonary Sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of an unknown aetiology. It can exist in many organs. Pulmonary and intrathoracic lymph nodes are most commonly involved. Lung sarcoidosis is uncommon in Asia. However, due to the large population of our country and the development of bronchoscopy, percutaneous lung puncture, and other medical technologies, the number of pulmonary sarcoidosis patients is on the rise. Pulmonary sarcoidosis patients have no obvious symptoms in the early stage, and the clinical manifestations in the later stage may vary from person to person. Eventually, the disease progresses to life-threatening pulmonary fibrosis. Therefore, patients with pulmonary sarcoidosis should receive a timely diagnosis. In recent years, the imaging features and serologic biomarkers of pulmonary sarcoidosis have been continuously studied. The diagnostic value of imaging and serologic biomarkers for pulmonary sarcoidosis is summarized below.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Fibrotic Pulmonary Sarcoidosis

Fibrotic pulmonary sarcoidosis (fPS) affects about 20% of patients. fPS carries a significant morbidity and mortality. However, its prognosis is highly variable, depending mainly on fibrosis extent, functional impairment severity, and the development of pulmonary hypertension. Moreover, fPS outcomes are also influenced by several other complications, including acute exacerbations, and infections. fPS natural history is unknown, in particular regarding the risk of progressive self-sustaining fibrosis. The management of fPS is challenging, including anti-inflammatory treatment if granulomatous activity persists, rehabilitation, and in highly selected patients antifibrotic treatment and lung transplantation.

Neurosarcoidosis

Sarcoidosis affects the nervous system in 5% of cases. 60% of cases involve the cranial and peripheral nerves, the remainder the central nervous system, in which a leptomeningitis, a pachymeningitis and a vasculitis may arise. Stroke and cerebral haemorrhage may occur, and certain infections in the brain are more likely with sarcoidosis. Patients respond well to treatment but oftentimes with residual neurological impairments which may be severe. A greater understanding of the disease and the need for early treatment and use of biological therapies have improved treatment outcome in recent times.

Sarcoidosis detected after COVID‑19 with T‑SPOT.TB positive: A case report

Sarcoidosis is an idiopathic multisystem disorder with unknown etiology. Due to clinical similarities among sarcoidosis, tuberculosis (TB) infection and malignant diseases (such as lymphoma, lung carcinoma and pituitary tumor), the diagnosis of sarcoidosis is challenging. The present report describes a case of sarcoidosis in a 48-year-old male with complaint of chest pain 1 month after Coronavirus disease 2019. The patient underwent whole-body 18F-fluorodeoxyglucose (18F-FDG) PET-CT imaging, which revealed multiple lymphadenopathies throughout the body without lung parenchyma involvement. Biochemical examinations such as T-SPOT.TB test and pathological examination of right supraclavicular lymph node revealed positive T-SPOT.TB but negative Ziehl-Neelsen staining. However, non-caseating epithelioid granulomas were observed in the mediastinal biopsy, indicating the diagnosis of sarcoidosis. The patient was clinically stable, and the symptom of chest pain was gradually relieved without any specific treatment. Outpatient follow-up continued every 3 months. The present case suggested a possible link between coronavirus infection and sarcoidosis, which suggests the advantages of 18F-FDG PET-CT for the detection of sarcoidosis. However, T-SPOT.TB is insufficient for differentiating between sarcoidosis and TB.

Clinical Manifestations and Management of Fibrotic Pulmonary Sarcoidosis

Fibrotic pulmonary sarcoidosis represents a distinct and relatively uncommon manifestation within the spectrum of sarcoidosis and has substantial morbidity and mortality. Due to the scarcity of research focused on this specific disease subtype, our current understanding of pathogenesis and optimal management remains constrained. This knowledge gap underscores the need for further investigation into areas such as targeted therapies, lung transplantation, and quality of life of patients with fibrotic pulmonary sarcoidosis. The primary aim of this review is to discuss recent developments within the realm of fibrotic pulmonary sarcoidosis to foster a more comprehensive understanding of the underlying mechanisms, prognosis, and potential treatment modalities.

The clinical value of quantitative cardiovascular molecular imaging: a step towards precision medicine

Cardiovascular diseases (CVD) are the leading cause of death worldwide and have an increasing impact on society. Precision medicine, in which optimal care is identified for an individual or a group of individuals rather than for the average population, might provide significant health benefits for this patient group and decrease CVD morbidity and mortality. Molecular imaging provides the opportunity to assess biological processes in individuals in addition to anatomical context provided by other imaging modalities and could prove to be essential in the implementation of precision medicine in CVD. New developments in single-photon emission computed tomography (SPECT) and positron emission tomography (PET) systems, combined with rapid innovations in promising and specific radiopharmaceuticals, provide an impressive improvement of diagnostic accuracy and therapy evaluation. This may result in improved health outcomes in CVD patients, thereby reducing societal impact. Furthermore, recent technical advances have led to new possibilities for accurate image quantification, dynamic imaging, and quantification of radiotracer kinetics. This potentially allows for better evaluation of disease activity over time and treatment response monitoring. However, the clinical implementation of these new methods has been slow. This review describes the recent advances in molecular imaging and the clinical value of quantitative PET and SPECT in various fields in cardiovascular molecular imaging, such as atherosclerosis, myocardial perfusion and ischemia, infiltrative cardiomyopathies, systemic vascular diseases, and infectious cardiovascular diseases. Moreover, the challenges that need to be overcome to achieve clinical translation are addressed, and future directions are provided.