Early detection of radiation-induced myocardial damage by [18F]AlF-NOTA-FAPI-04 PET/CT imaging

C-X-C-chemokine-receptor-type-4 as a potential target for diagnosis and treatment of acute radiation-induced esophagitis

PURPOSE

Acute radiation-induced esophagitis (ARIE) is a common and dose-limiting adverse reaction associated with radiotherapy for thoracic tumors. mRNA sequencing identified CXCR4 as a potential target for noninvasive imaging of ARIE and significant up-regulation of CXCR4 expression was further confirmed in ARIE experimental animal model and clinical samples. This research investigated the feasibility of targeting CXCR4 for the diagnosis and treatment of ARIE.

METHODS

ARIE models were established, and magnetic resonance imaging was performed. Dynamic, blocking, histopathological studies, mRNA-sequencing and flow cytometry were conducted. The feasibility of an 18F-labeled polypeptide (QHY-04) targeting CXCR4 for detecting ARIE was validated. CXCR4 blockade using AMD3100 was applied immediately post radiotherapy.

RESULTS

Increased signal intensity in the esophagus and surrounding tissues was observed in ARIE models, with clinical manifestations confirmed by H&E staining. Immunofluorescence staining demonstrated significant CXCR4 up-regulation. Significantly increased [18F]AlF-NOTA-QHY-04 uptake in the irradiated esophagus was observed via PET imaging. Immune cell infiltration and flow cytometry identified CXCR4-positive neutrophils and monocytes as the primary source of the radiotracer. AMD3100-mediated CXCR4 blockade significantly reduced ARIE.

CONCLUSION

CXCR4-targeted PET/CT facilitates noninvasive detection of ARIE in experimental animal models. CXCR4 blockade mitigates ARIE, highlighting CXCR4 as a promising theranostic target of ARIE.

Gallium-Labeled PET Radiopharmaceuticals in Cardiovascular Disease

Gallium-labeled positron emission tomography (PET) probes targeting activated fibroblasts or somatostatin receptor expression are frequently used for varying applications in oncology. With the widespread availability of 68Ge/68Ga generators and cold kits, 68Ga tracers have become a main tool in molecular imaging. These tracers, such as [68Ga]Ga-DOTA-TATE, [68Ga]Ga-FAPI, and [68Ga]Ga-pentixafor, allow targeted imaging of the key pathological processes, including inflammation, fibrosis, and necrosis. This review highlights their potential in conditions like myocardial infarction, cardiac sarcoidosis, myocarditis, and other cardiomyopathies. Clinical and preclinical studies underscore their utility in visualizing active disease processes, predicting outcomes, and guiding therapeutic strategies. However, challenges remain, including the need for standardization, larger clinical trials, and integration into routine practice. These advancements position 68Ga-based PET as a promising modality for enhancing diagnostic precision and personalized treatment in cardiovascular disease.

Imaging of Cardiac Fibrosis: How Far Have We Moved From Extracellular to Cellular?

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. Myocardial fibrosis plays an important role in adverse outcomes such as heart failure and arrhythmias. As the pathological response and degree of scarring, and therefore clinical presentation varies from patient to patient, early detection of fibrosis is crucial for identifying the appropriate treatment approach and forecasting the progression of a disease along with the likelihood of disease-related mortality. Current imaging modalities provides information about either decreased function or extracellular signs of fibrosis. Targeting activated fibroblasts represents a burgeoning approach that could offer insights prior to observable functional alterations, presenting a promising focus for potential anti-fibrotic therapeutic interventions at cellular level. In this article, we provide an overview of imaging cardiac fibrosis and discuss the role of different advanced imaging modalities with the focus on novel non-invasive imaging of activated fibroblasts.

Advances in injectable hydrogels for radiation-induced heart disease

Radiological heart damage (RIHD) is damage caused by unavoidable irradiation of the heart during chest radiotherapy, with a long latency period and a progressively increasing proportion of delayed cardiac damage due to conventional doses of chest radiotherapy. There is a risk of inducing diseases such as acute/chronic pericarditis, myocarditis, delayed myocardial fibrosis and damage to the cardiac conduction system in humans, which can lead to myocardial infarction or even death in severe cases. This paper details the pathogenesis of RIHD and gives potential targets for treatment at the molecular and cellular level, avoiding the drawbacks of high invasiveness and immune rejection due to drug therapy, medical device implantation and heart transplantation. Injectable hydrogel therapy has emerged as a minimally invasive tissue engineering therapy to provide necessary mechanical support to the infarcted myocardium and to act as a carrier for various bioactive factors and cells to improve the cellular microenvironment in the infarcted area and induce myocardial tissue regeneration. Therefore, this paper combines bioactive factors and cellular therapeutic mechanisms with injectable hydrogels, presents recent advances in the treatment of cardiac injury after RIHD with different injectable gels, and summarizes the therapeutic potential of various types of injectable hydrogels as a potential solution.

Early and Accurate Detection of Radiation-induced Heart Damage by Cardiodynamicsgram

Cardiodynamicsgram (CDG) has emerged recently as a noninvasive spatiotemporal electrocardiographic method for subtle cardiac dynamics information analysis within electrocardiogram (ECG). This study explored the feasibility of CDG for detecting radiation-induced heart damage (RIHD) in a rat model. A single radiation dose of 40 Gy was delivered to the cardiac apex of female Wistar rats. First, CDG was generated through dynamic modeling of ECG signals using the deterministic learning algorithm. Furthermore, CDG indexes were calculated using the wavelet transform and entropy. In this model, CDG entropy indexes decreased significantly after radiotherapy. The shape of CDG changed significantly after radiotherapy (irregular shape) compared with controls (regular shape). Macrophage and fibrosis in myocardium of rats increased significantly after radiotherapy. CDG changes after radiotherapy were significantly correlated with histopathological changes and occurred significantly earlier than histopathological changes. This study provides an experimental basis for the clinical application of CDG for the early detection of RIHD.

Early, non-invasive detection of radiation-induced lung injury using PET/CT by targeting CXCR4

PURPOSE

Radiation-induced lung injury (RILI) is a severe side effect of radiotherapy (RT) for thoracic malignancies and we currently lack established methods for the early detection of RILI. In this study, we synthesized a new tracer, [18F]AlF-NOTA-QHY-04, targeting C-X-C-chemokine-receptor-type-4 (CXCR4) and investigated its feasibility to detect RILI.

METHODS

An RILI rat model was constructed and scanned with [18F]AlF-NOTA-QHY-04 PET/CT and [18F]FDG PET/CT periodically after RT. Dynamic, blocking, autoradiography, and histopathological studies were performed on the day of peak uptake. Fourteen patients with radiation pneumonia, developed during or after thoracic RT, were subjected to PET scan using [18F]AlF-NOTA-QHY-04.

RESULTS

The yield of [18F]AlF-NOTA-QHY-04 was 28.5-43.2%, and the specific activity was 27-33 GBq/μmol. [18F]AlF-NOTA-QHY-04 was mainly excreted through the kidney. Significant increased [18F]AlF-NOTA-QHY-04 uptake in the irradiated lung compared with that in the normal lung in the RILI model was observed on day 6 post-RT and peaked on day 14 post-RT, whereas no apparent uptake of [18F]FDG was shown on days 7 and 15 post-RT. MicroCT imaging did not show pneumonia until 42 days post-RT. Significant intense [18F]AlF-NOTA-QHY-04 uptake was confirmed by autoradiography. Immunofluorescence staining demonstrated expression of CXCR4 was significantly increased in the irradiated lung tissue, which correlated with results obtained from hematoxylin-eosin and Masson's trichrome staining. In 14 patients with radiation pneumonia, maximum standardized uptake values (SUVmax) were significantly higher in the irradiated lung compared with those in the normal lung. SUVmax of patients with grade 2 RILI was significantly higher than that of patients with grade 1 RILI.

CONCLUSION

This study indicated that [18F]AlF-NOTA-QHY-04 PET/CT imaging can detect RILI non-invasively and earlier than [18F]FDG PET/CT in a rat model. Clinical studies verified its feasibility, suggesting the clinical potential of [18F]AlF-NOTA-QHY-04 as a PET/CT tracer for early monitoring of RILI.

Highlighting Fibroblasts Activation in Fibrosis: The State-of-The-Art Fibroblast Activation Protein Inhibitor PET Imaging in Cardiovascular Diseases

Fibrosis is a common healing process that occurs during stress and injury in cardiovascular diseases. The evolution of fibrosis is associated with cardiovascular disease states and causes adverse effects. Fibroblast activation is responsible for the formation and progression of fibrosis. The incipient detection of activated fibroblasts is important for patient management and prognosis. Fibroblast activation protein (FAP), a membrane-bound serine protease, is almost specifically expressed in activated fibroblasts. The development of targeted FAP-inhibitor (FAPI) positron emission tomography (PET) imaging enabled the visualisation of FAP, that is, incipient fibrosis. Recently, research on FAPI PET imaging in cardiovascular diseases increased and is highly sought. Hence, we comprehensively reviewed the application of FAPI PET imaging in cardiovascular diseases based on the state-of-the-art published research. These studies provided some insights into the value of FAPI PET imaging in the early detection of cardiovascular fibrosis, risk stratification, response evaluation, and prediction of the evolution of left ventricular function. Future studies should be conducted with larger populations and multicentre patterns, especially for response evaluation and outcome prediction.

Tales from the future-nuclear cardio-oncology, from prediction to diagnosis and monitoring

Cancer and cardiovascular diseases (CVD) often share common risk factors, and patients with CVD who develop cancer are at high risk of experiencing major adverse cardiovascular events. Additionally, cancer treatment can induce short- and long-term adverse cardiovascular events. Given the improvement in oncological patients' prognosis, the burden in this vulnerable population is slowly shifting towards increased cardiovascular mortality. Consequently, the field of cardio-oncology is steadily expanding, prompting the need for new markers to stratify and monitor the cardiovascular risk in oncological patients before, during, and after the completion of treatment. Advanced non-invasive cardiac imaging has raised great interest in the early detection of CVD and cardiotoxicity in oncological patients. Nuclear medicine has long been a pivotal exam to robustly assess and monitor the cardiac function of patients undergoing potentially cardiotoxic chemotherapies. In addition, recent radiotracers have shown great interest in the early detection of cancer-treatment-related cardiotoxicity. In this review, we summarize the current and emerging nuclear cardiology tools that can help identify cardiotoxicity and assess the cardiovascular risk in patients undergoing cancer treatments and discuss the specific role of nuclear cardiology alongside other non-invasive imaging techniques.

The Potential of Fibroblast Activation Protein-Targeted Imaging as a Biomarker of Cardiac Remodeling and Injury

PURPOSE OF REVIEW

Cardiovascular disease features adverse fibrotic processes within the myocardium, leading to contractile dysfunction. Activated cardiac fibroblasts play a pivotal role in the remodeling and progression of heart failure, but conventional diagnostics struggle to identify early changes in cardiac fibroblast dynamics. Emerging imaging methods visualize fibroblast activation protein (FAP) as a marker of activated fibroblasts, enabling non-invasive quantitative measurement of early cardiac remodeling.

RECENT FINDINGS

Retrospective analysis of oncology patient cohorts has identified cardiac uptake of FAP radioligands in response to various cardiovascular conditions. Small scale studies in dedicated cardiac populations have revealed FAP upregulation in injured myocardium, wherein the area of upregulation predicts subsequent ventricle dysfunction. Recent studies have demonstrated that silencing of FAP-expressing fibroblasts can reverse cardiac fibrosis in disease models. The parallel growth of FAP-targeted imaging and therapy provides the opportunity for imaging-based monitoring and refinement of treatments targeting cardiac fibroblast activation.