Imaging Inflammation - From Whole Body Imaging to Cellular Resolution

Impact of biocontainment on small animal PET performance adapted for BSL-2/3 infectious disease imaging research

BACKGROUND

Biocontainment protocols are critical for conducting infectious disease (ID) research, particularly when using small animal models in biosafety level (BSL) 2/3 environments. This study evaluates the impact of poly-methyl methacrylate (PMMA) containment vessels on the performance of preclinical positron emission tomography (PET) systems. We tested containment vessels designed with varying wall thicknesses (3, 6, and 9 mm) to simulate ID imaging facility equipment and protocols. Through the use of multicomponent phantoms and in vivo mouse models of Staphylococcus aureus infection, we assessed key performance metrics including count rate, image quality, activity recovery, and spatial resolution.

RESULTS

The results indicate that the use of PMMA containment causes only minor reductions in imaging performance. The thickest PMMA (9 mm) led to a maximum 6.8% decrease in count rate, which remains well within the acceptable range of variation. Effects on spatial resolution were most noticeable for smaller structures within the phantom study, with a 19.65% difference in full width at half maximum (FWHM) for the thickest walled vessel. In vivo, using infected mice, the containment devices had modest effects on the task of activity concentration to be detected at the infection site, even with the thickest PMMA tube.

CONCLUSION

These findings suggest that PMMA biocontainment vessels have small but measurable impact on preclinical PET system performance, making them a viable and cost-effective solution for conducting infectious disease imaging under BSL-2/3 conditions. Specifically, the thinnest containment (3 mm) had only minor effects on all tested parameters, suggesting it is well-suited for use in ID enclosures while maintaining accurate qualitative and quantitative assessments. This approach may reduce the burden for fully separate and specialized modifications for BSL-3 imaging facilities, and can be broadly applied to preclinical research involving pathogenic organisms.

A method framework of semi-automatic knee bone segmentation and reconstruction from computed tomography (CT) images

Background

Accurate delineation of knee bone boundaries is crucial for computer-aided diagnosis (CAD) and effective treatment planning in knee diseases. Current methods often struggle with precise segmentation due to the knee joint's complexity, which includes intricate bone structures and overlapping soft tissues. These challenges are further complicated by variations in patient anatomy and image quality, highlighting the need for improved techniques. This paper presents a novel semi-automatic segmentation method for extracting knee bones from sequential computed tomography (CT) images.

Methods

Our approach integrates the fuzzy C-means (FCM) algorithm with an adaptive region-based active contour model (ACM). Initially, the FCM algorithm assigns membership degrees to each voxel, distinguishing bone regions from surrounding soft tissues based on their likelihood of belonging to specific bone regions. Subsequently, the adaptive region-based ACM utilizes these membership degrees to guide the contour evolution and refine segmentation boundaries. To ensure clinical applicability, we further enhance our method using the marching cubes algorithm to reconstruct a three-dimensional (3D) model. We evaluated the method on six randomly selected knee joints.

Results

We evaluated the method using quantitative metrics such as the Dice coefficient, sensitivity, specificity, and geometrical assessment. Our method achieved high Dice scores for the femur (98.95%), tibia (98.10%), and patella (97.14%), demonstrating superior accuracy. Remarkably low root mean square distance (RSD) values were obtained for the tibia and femur (0.5±0.14 mm) and patella (0.6±0.13 mm), indicating precise segmentation.

Conclusions

The proposed method offers significant advancements in CAD systems for knee pathologies. Our approach demonstrates superior performance in achieving precise and accurate segmentation of knee bones, providing valuable insights for anatomical analysis, surgical planning, and patient-specific prostheses.

Current and future applications of light-sheet imaging for identifying molecular and developmental processes in autism spectrum disorders

Autism spectrum disorder (ASD) is identified by a set of neurodevelopmental divergences that typically affect the social communication domain. ASD is also characterized by heterogeneous cognitive impairments and is associated with cooccurring physical and medical conditions. As behaviors emerge as the brain matures, it is particularly essential to identify any gaps in neurodevelopmental trajectories during early perinatal life. Here, we introduce the potential of light-sheet imaging for studying developmental biology and cross-scale interactions among genetic, cellular, molecular and macroscale levels of circuitry and connectivity. We first report the core principles of light-sheet imaging and the recent progress in studying brain development in preclinical animal models and human organoids. We also present studies using light-sheet imaging to understand the development and function of other organs, such as the skin and gastrointestinal tract. We also provide information on the potential of light-sheet imaging in preclinical drug development. Finally, we speculate on the translational benefits of light-sheet imaging for studying individual brain-body interactions in advancing ASD research and creating personalized interventions.

Advanced methods and novel biomarkers in autoimmune diseases ‑ a review of the recent years progress in systemic lupus erythematosus

There are several autoimmune and rheumatic diseases affecting different organs of the human body. Multiple sclerosis (MS) mainly affects brain, rheumatoid arthritis (RA) mainly affects joints, Type 1 diabetes (T1D) mainly affects pancreas, Sjogren's syndrome (SS) mainly affects salivary glands, while systemic lupus erythematosus (SLE) affects almost every organ of the body. Autoimmune diseases are characterized by production of autoantibodies, activation of immune cells, increased expression of pro-inflammatory cytokines, and activation of type I interferons. Despite improvements in treatments and diagnostic tools, the time it takes for the patients to be diagnosed is too long, and the main treatment for these diseases is still non-specific anti-inflammatory drugs. Thus, there is an urgent need for better biomarkers, as well as tailored, personalized treatment. This review focus on SLE and the organs affected in this disease. We have used the results from various rheumatic and autoimmune diseases and the organs involved with an aim to identify advanced methods and possible biomarkers to be utilized in the diagnosis of SLE, disease monitoring, and response to treatment.

Exploring the Usability of α-MSH-SM-Liposome as an Imaging Agent to Study Biodegradable Bone Implants In Vivo

Novel biodegradable metal alloys are increasingly used as implant materials. The implantation can be accompanied by an inflammatory response to a foreign object. For studying inflammation in the implantation area, non-invasive imaging methods are needed. In vivo imaging for the implanted area and its surroundings will provide beneficiary information to understand implant-related inflammation and help to monitor it. Therefore, inflammation-sensitive fluorescent liposomes in rats were tested in the presence of an implant to evaluate their usability in studying inflammation. The sphingomyelin-containing liposomes carrying alpha-melanocyte-stimulating hormone (α-MSH)-peptide were tested in a rat bone implant model. The liposome interaction with implant material (Mg-10Gd) was analyzed with Mg-based implant material (Mg-10Gd) in vitro. The liposome uptake process was studied in the bone-marrow-derived macrophages in vitro. Finally, this liposomal tracer was tested in vivo. It was found that α-MSH coupled sphingomyelin-containing liposomes and the Mg-10Gd implant did not have any disturbing influence on each other. The clearance of liposomes was observed in the presence of an inert and biodegradable implant. The degradable Mg-10Gd was used as an alloy example; however, the presented imaging system offers a new possible use of α-MSH-SM-liposomes as tools for investigating implant responses.

Molecular Mechanisms of Inflammation in Sarcopenia: Diagnosis and Therapeutic Update

Sarcopenia is generally an age-related condition that directly impacts the quality of life. It is also related to chronic diseases such as metabolic dysfunction associated with diabetes and obesity. This means that everyone will be vulnerable to sarcopenia at some point in their life. Research to find the precise molecular mechanisms implicated in this condition can increase knowledge for the better prevention, diagnosis, and treatment of sarcopenia. Our work gathered the most recent research regarding inflammation in sarcopenia and new therapeutic agents proposed to target its consequences in pyroptosis and cellular senescence. Finally, we compared dual X-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and ultrasound (US) as imaging techniques to diagnose and follow up on sarcopenia, indicating their respective advantages and disadvantages. Our goal is for the scientific evidence presented here to help guide future research to understand the molecular mechanisms involved in sarcopenia, new treatment strategies, and their translation into clinical practice.

The development and clinical application of microscopic endoscopy for in vivo optical biopsies: Endocytoscopy and confocal laser endomicroscopy

Endoscopies are crucial for detecting and diagnosing diseases in gastroenterology, pulmonology, urology, and other fields. To accurately diagnose diseases, sample biopsies are indispensable and are currently considered the gold standard. However, random 4-quadrant biopsies have sampling errors and time delays. To provide intraoperative real-time microscopic images of suspicious lesions, microscopic endoscopy for in vivo optical biopsy has been developed, including endocytoscopy and confocal laser endomicroscopy. This article reviews recent advances in technology and clinical applications, as well as their shortcomings and future directions.

Utilizing Sphingomyelinase Sensitizing Liposomes in Imaging Intestinal Inflammation in Dextran Sulfate Sodium-Induced Murine Colitis

Inflammatory bowel disease (IBD) is characterized by chronic inflammation in the gastrointestinal tract, resulting in severe symptoms. At the moment, the goal of medical treatments is to reduce inflammation. IBD is treated with systemic anti-inflammatory compounds, but they have serious side effects. The treatment that is most efficient and causes the fewest side effects would be the delivery of the drugs on the disease site. This study aimed to investigate the suitability of sphingomyelin (SM) containing liposomes to specifically target areas of inflammation in dextran sulfate sodium-induced murine colitis. Sphingomyelin is a substrate to the sphingomyelinase enzyme, which is only present outside cells in cell stress, like inflammation. When sphingomyelin consisting of liposomes is predisposed to the enzyme, it causes the weakening of the membrane structure. We demonstrated that SM-liposomes are efficiently taken up in intestinal macrophages, indicating their delivery potential. Furthermore, our studies showed that sphingomyelinase activity and release are increased in a dextran sulfate sodium-induced IBD mouse model. The enzyme appearance in IBD disease was also traced in intestine samples of the dextran sulfate sodium-treated mice and human tissue samples. The results from the IBD diseased animals, treated with fluorescently labeled SM-liposomes, demonstrated that the liposomes were taken up preferentially in the inflamed colon. This uptake efficiency correlated with sphingomyelinase activity.