Molecular Imaging and Biology最新文献

Purpose: In this study, we report the development and characterization of a copper-64 (⁶⁴Cu) radiolabeled anti-EphA2 minibody (Mb) for pre-treatment characterization of antigen expression via Positron Emission Tomography (PET). Minibodies, ≈85 kDa molecular weight antibody fragments, are advantageous as targeting molecules due to accelerated serum clearance which enables imaging at earlier time points relative to the parent IgG. As EphA2, a tyrosine kinase receptor, is overexpressed in various cancer types with minimal expression in normal tissue, rapid quantification of EphA2 expression could be beneficial for patient stratification.

Procedures: Recombinantly produced anti-EphA2-Mb was evaluated for purity, stability, affinity, and in vivo target localization. Following bifunctional chelator conjugation, radiolabeling with ⁶⁴Cu and evaluating purity, stability and immunoreactivity of resultant radioimmunoconjugate, [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb, 11.1 MBq (300 μCi) and 0.2 MBq (5 μCi) doses were administered to HT1080-fibrosarcoma-bearing nude mice for in-vivo PET imaging and ex-vivo biodistribution analyses respectively at 4 and 24 h post-injection (p.i.). Antigen-specificity was assessed via a blocked control group which received the dose co-administered with non-radiolabeled anti-EphA2-Mb.

Results: Anti-EphA2-Mb produced via recombinant protein expression was pure, stable and had high binding affinity to human EphA2 antigen (K_D = 0.63 ± 0.24 nM). When labeled with ⁶⁴Cu via NOTA, [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb had high purity, in-vitro stability in PBS and mouse serum up to 24 h, and high immunoreactivity. On administering to tumor-bearing mice, [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb exhibited rapid tumor targeting with 25.53±2.92%ID/g at 4 h, and 22.13±7.68%ID/g at 24 h p.i. Competitive inhibition reduced tumor uptake (11.24±0.88%D/g, 24 h p.i., p = 0.0286). There was minimal uptake of the radiotracer in non-target tissues, except kidney and liver, and fast clearance from the blood, with high tumor to blood ratios. Tumor SUV_mean values obtained from region of interest (ROI) Quantification of the PET images were 1.13±0.03 and 1.08±0.06 at 4 and 24 h respectively.

Conclusion: Our findings demonstrate that anti-EphA2-Mb is an excellent targeting molecule, and [⁶⁴Cu]Cu-NOTA-anti-EphA2-Mb is a promising immunoPET agent with potential for use for other theranostic applications.

Preclinical biodistribution studies are required at an early stage of radiopharmaceutical development to determine tracer pharmacokinetics in clinically relevant animal models of human diseases. When combined with quantitative analysis from non-invasive imaging, biodistribution experiments provide essential data on the uptake, retention, binding specificity, metabolism, and clearance of radiotracers in both target and non-target tissues. Most research groups have developed in-house protocols to perform these studies in a reproducible manner. However, there is a general lack of consistency in how different groups carry out biodistribution experiments. In addition to practical differences that occur during tissue collection (for example, washing and blotting dry the tissue, perfusion, sampling site for a given tissue, etc.), other aspects of biodistribution experiments, which often vary include the methods used for calibrating the injected activity, the processes used to calculate mass normalized tissue uptake (i.e. percentage of injected dose per gram [%ID g^-1] or percentage of injected activity per gram of tissue [%IA g^-1]) values, differences in data processing and statistical analyses (particularly error propagations and calculation of tissue contrast ratios), and variations in how the methods and data are reported and interpreted. This variability hinders the direct comparison of datasets produced at different laboratories. Here, we present a comprehensive guideline for conducting ex vivo biodistribution experiments with radiotracers in rodent models. An open source, freely accessible online biodistribution calculator and associated spreadsheet are provided which can be employed to compute the percent of injected dose per gram of tissue (%ID g^-1), standardized uptake value (SUV by mass), and target-to-background tissue contrast ratios. Finally, advice concerning biodistribution data presentation and statistical analysis are given to help the reader harness the full power of ex vivo biodistribution studies in radiotracer development.

Purpose: Lymph node (LN) excision is critical in oncologic surgery to provide important therapeutic and diagnostic information. LN evaluation helps in staging cancers, predicting prognosis and improving survival. The ultimate wish of a surgical oncologist would be to localize and dissect all pathologically positive LNs while avoiding the morbidity of removing true negative LNs. The goal of our study was to identify a reliable marker for intraoperative molecular imaging of LNs with cancer cells from non-small cell lung cancer versus a LN without.

Procedures: We identified Epithelial Cell Adhesion Molecule (EpCAM), a membrane protein normally expressed in epithelial tissues including lung. We performed immunofluorescence staining on human specimens with a conjugated anti-EpCAM monoclonal antibody.

Results: Fluorescence was significantly higher in LNs with metastases as shown in 48 positive LNs from patients with resected primary lung cancer. There was high fluorescence in both hilar and mediastinal LNs, and in all primary tumor histologies.

Conclusions: EpCAM may be useful for the surgical oncologist for intraoperative molecular imaging of positive LNs from lung cancer.

Purpose: Tuberculosis (TB) continues to afflict global health. Therefore, a deeper understanding of the host response mechanisms that underly pathogenesis versus disease control upon infection with Mycobacterium tuberculosis (Mtb) is required to leverage the development of improved therapeutic or prophylactic TB treatment regimens. In the present work positron emission tomography (PET) using [¹⁸F]DPA714 is piloted as a tracer of the mitochondrial translocator protein TSPO that mainly targets macrophages.

Procedures: We compared two tracers: [¹⁸F]DPA714 to the widely applied marker [¹⁸F]FDG to visualize the development of experimental pulmonary TB in three rhesus monkeys (Macaca mulatta), that were infected with Mtb by repeated low dose exposure. Next to baseline recordings prior to infectious challenge, two PETs at a two-weeks interval were acquired early after the manifestation of TB infection for each of the respective tracers.

Results & conclusions: Here, we demonstrate that both PET tracers detected Mtb infection. The inflammatory response tracked by [¹⁸F]FDG progressively increased in line with the developing TB pathology, while [¹⁸F]DPA714 showed a transient signal in lungs and lung-draining hilar lymph nodes. This study underpins the potential value of different tracers to investigate cellular and molecular host response cascades in experimental medicine settings, in this case, into a (transient) local involvement of myeloid immune cell activation versus inflammation-associated glucose consumption in pulmonary TB.

Purpose: Influenza (flu) is a respiratory illness caused by lung infection with influenza viruses. This study establishes lung [¹⁸F]FDG uptake by PET/CT as an accurate measure of lung inflammation associated with influenza A virus (IAV) H1N1 infection.

Procedures: Immunocompetent BALB/c mice were infected with a highly lethal dose of influenza A virus (PR8 strain) and intravenously injected with [¹⁸F]FDG. Ex vivo tissue biodistribution was assessed by gamma counting, while in vivo tissue biodistribution was analyzed by VOI analysis of PET/CT images. Disease severity was also investigated by VOI measurements of high-resolution lung CT images. Infection and inflammation were confirmed by immunohistochemical staining; while viral replication and expression of inflammatory proteins (cytokines and chemokines) were measured in lung tissues by qRT-PCR and multiplex ELISA, respectively.

Results: Ex vivo tissue biodistribution of [¹⁸F]FDG revealed that the lungs were the only relevant imaging target in influenza-infected mice. Lung [¹⁸F]FDG uptake on PET/CT images increased with disease severity and exhibited 1.53-fold increase on day 1 and up to 2.63-fold increase on day 6 post-infection compared to pre-infection levels. Lung uptake correlated with the increased production of pro-inflammatory proteins associated with influenza infection.

Conclusions: Lung [¹⁸F]FDG uptake on PET images is a non-invasive molecular biomarker of influenza-A virus-induced lung inflammation and disease, effectively distinguishing infected from non-infected lungs as early as day 1 post-infection.

Nanophotonics-the manipulation of light at the nanometer scale within biological systems-is transforming molecular imaging and photobiology, enabling advanced in vivo imaging, diagnostics, and therapy guidance. This review outlines core nanophotonic principles, including surface plasmon resonance, optical confinement, and photon-matter interactions, underpinning emerging molecular imaging probes and diagnostic tools. Biocompatible nanomaterials such as quantum dots, gold nanoparticles, and photonic metamaterials enable highly sensitive, selective imaging and biosensing for early, minimally invasive disease detection and monitoring. Targeted photothermal and photodynamic therapies using near-infrared (NIR) and NIR-II light advance image-guided interventions, allowing deeper tissue penetration with minimal collateral damage. We also discuss the integration of nanophotonic components into lab-on-a-chip and microfluidic platforms for point-of-care diagnostics, accelerating clinical translation. Additionally, machine learning enhances molecular imaging analysis and probe optimization, enabling real-time data interpretation and predictive modeling tailored to patient-specific profiles. This article is a narrative review that emphasizes recent advancements from 2021-2025, identified through targeted database searches, highlighting progress, research gaps, and future perspectives for disease-specific applications. While these advances hold promise, challenges remain in biocompatibility, light penetration, scalability, and regulatory approval. Collectively, integrating nanophotonics with molecular imaging, machine learning, and personalized medicine frameworks marks a step toward next-generation precision diagnostics and image-guided therapeutics.

Ostrich eggs have recently attracted interest as an alternative model in preclinical nuclear medicine imaging. The ability to be used in clinical PET/CT (positron emission tomography/computed tomography) systems and their ethical profile are advantageous over conventional rodent models and other avian systems. Nevertheless, concerns regarding radiation exposure during repeated CT (computed tomography) imaging of developing embryos remain inadequately addressed. This study aimed to characterize the attenuation impact of eggshells in ostrich eggs and to evaluate the potential for organ-specific dose assessment. A representative ostrich egg was selected from a cohort of 168 eggs and used to construct a dimensionally matched 3D-printed phantom. Organ weights of 83 embryos were documented on development day (DD) 37 to provide a basis for future organ-level dosimetric modeling. Thermoluminescence dosimeters (TLDs) were positioned along the z-axis within both the egg and phantom, and CT dose distributions were measured using a clinical PET/CT system. The mean absorbed dose in the real egg was 16.3 ± 2.0% lower than in the phantom, attributable to radiation attenuation by the 1.89 ± 0.12 mm thick eggshell. CTDI (computed tomography dose index) values remained stable across developmental stages (DD 0-37). Our findings confirm that the ostrich eggshell exerts a significant shielding effect during CT imaging. While ostrich eggs are suitable for serial in-ovo imaging, embryo positioning remains a major limitation for precise dosimetry. Organ weight data enable potential use of AI (artificial intelligence)-based modeling to improve spatial dosimetry accuracy. This study provides essential groundwork for dose optimization and radioprotection in preclinical imaging protocols using ostrich eggs.

Theranostics, a concept combining "therapy" and "diagnostics", is poised to enter an exponential growth phase. By using specific diagnostic markers to guide the selection and application of targeted treatments directed at those markers, this approach aims to improve effectiveness and reduce unnecessary interventions. While several agents have been approved by the FDA recently, multiple additional theranostics are being developed, studied in clinical trials and expected to enter clinical practice in short order. As part of the "Translation of New Therapy (TNT) Interest Group's Radiotheranostics Kick-off" pre-meeting of the annual World Molecular Imaging Conference (WMIC) 2024 over 350 attendees with 10% leaders from industry, 60% senior and junior investigators in academia and 30% trainees discussed the key challenges and opportunities in implementing a theranostic research program in academia, which are addressed in this white paper. Overarching themes included funding, regulatory hurdles, and workforce training. Panel recommendations included leveraging existing expertise and patient populations, securing revenue streams, exploring alternative funding sources, and developing a multifaceted approach to promote training, education and public awareness, including fostering academic-industry partnerships. By shedding light on the gap between research and real-world program implementation, this white paper and forthcoming pre-meetings at WMIC aim to define a practical framework for building successful programs based on insights from recent research.

Sarcopenia, characterized by the progressive loss of skeletal muscle mass and function, remains a formidable challenge in aging populations. This review synthesizes current knowledge on its multifactorial pathogenesis, including mitochondrial dysfunction, oxidative stress, chronic inflammation, apoptosis, and satellite cell impairment. Neuromuscular alterations such as motor unit Remodeling and neuromuscular junction degeneration further exacerbate functional decline. Diagnostic approaches, ranging from DXA, CT, MRI, and ultrasound imaging to functional assessments like handgrip strength and gait speed, exhibit variability that complicates standardization. Therapeutic strategies are equally versatile. Resistance-based exercise and targeted nutritional support remain first-line, but late-phase trials of myostatin-neutralising antibodies (e.g., LY2495655, bimagrumab) and oral selective androgen-receptor modulators (SARMs; e.g., enobosarm, GSK2881078) now show dose-dependent gains in appendicular lean mass and preliminary functional benefits, signalling that combination regimens integrating lifestyle and drug therapy are imminent. Integration of these approaches with personalized medicine paradigms and AI-driven diagnostic tools holds promise for improved outcomes. This review also outlines critical research areas including mechanistic studies, diagnostic standardization, and translational gaps between preclinical models and clinical application. Addressing these challenges requires an interdisciplinary strategy that encompasses molecular, clinical, and public health perspectives to mitigate the personal and societal impacts of sarcopenia. Future efforts must focus on harmonizing diagnostic criteria, refining therapeutic regimens, and leveraging emerging technologies to develop targeted interventions that preserve muscle function and enhance quality of life in the aging population.

Purpose: Despite advancements in colorectal cancer (CRC) therapy, surgery remains the only curative option. Incomplete resection resulting in tumor cell positive surgical margins occurs in ~ 7% of CRC surgeries and is associated with recurrence and poor prognosis. Fluorescence-guided surgery (FGS) enhances tumor detection and enables real-time identification of tumor margins. Claudins, a large family of tight junction proteins, are being explored as cancer biomarkers and therapeutic targets due to their presence on the cell surface, tissue-specific expression, and selective upregulation in carcinomas. Claudin-1 (CLDN1) is overexpressed in CRC and associated with therapy resistance and metastasis, making it a promising target for fluorescence-based tumor detection.

Procedures: CLDN1 expression in CRC was analyzed using the Cancer Genome Atlas Colorectal Adenocarcinoma (TCGA-COAD) dataset. To enable in vivo tumor detection, a CLDN1 monoclonal antibody was conjugated to a near-infrared fluorescent dye (CLDN1-IR800). Sensitivity, specificity, and tumor-to-background ratio were tested in vitro and in vivo using CRC cell lines, patient-derived organoids, and an orthotopic, syngeneic model of CRC metastasis.

Results: This study demonstrates that CLDN1 is upregulated in 100% of CRC tumors compared to patient-matched normal adjacent colon in the TCGA-COAD dataset, with an average 40-fold increase in expression. CLDN1-IR800 showed specific binding and strong fluorescence in CLDN1-expressing CRC cells, with minimal signal in non-expressing cells or IgG-IR800 controls. In vivo, CLDN1-IR800 produced a significantly higher tumor-to-background ratio in CLDN1-expressing CRC cell line and patient-derived organoid xenografts compared to CLDN1-negative tumors or IgG-IR800-injected mice. Necropsy revealed significantly higher fluorescence in tumors than in other organs. In an orthotopic syngeneic mouse model, both primary and metastatic lesions were detectable. Ex vivo imaging confirmed signal in a panel of patient-derived organoids.

Conclusions: These findings demonstrate CLDN1's potential as a target for tumor detection and FGS in CRC.