npj Imaging最新文献

Myocardial ischemia induces tissue injury with subsequent inflammation and recruitment of immune cells. Besides myocardial tissue characterization, magnetic resonance imaging (MRI) allows for functional assessment using molecular imaging contrast agents. Here, we assessed ischemic cardiac lesions non-invasively directly after ischemia/reperfusion (I/R) in a porcine model by advanced MRI techniques and molecular imaging, targeting the cell adhesion molecule P-selectin functionalized with microparticles of iron oxide (MPIO). We used a closed-chest model of I/R by temporary coronary balloon-occlusion, real time 3T MRI-guided coronary injection of MPIO-based contrast agents, as well as injury, edema and iron-sensitive MRI. Within the first hours after I/R, we found T1 mapping to be most sensitive for tissue injury, with no changes in edema-sensitive MRI. Intriguingly, P-selectin MPIO contrast agent selectively enhanced the ischemic area in iron-sensitive MRI. In conclusion, this approach allows for sensitive detection of early myocardial inflammation beyond traditional edema-sensitive imaging.

Despite its introduction in the 1970's, it is only recent technology advances that have propelled growth in clinical optoacoustic (photoacoustic) imaging over the past decade. We analytically present the broad landscape of clinical optoacoustic applications in the context of these key technology advances, the unique contrast achieved, and the tissue biomarkers resolved. We then discuss current challenges and future opportunities to address the unmet clinical needs.

Despite significant strides in lymphatic system imaging, the timely diagnosis of lymphatic disorders remains elusive. This is driven by the absence of standardized, non-invasive, reliable, quantitative methods for real-time functional analysis of lymphatic contractility with adequate spatial and temporal resolution. Here, we address this unmet need by integrating near-infrared fluorescence lymphangiography imaging with an innovative analytical workflow that combines data acquisition, signal processing, and statistical analysis to integrate traditional peak-and-valley analysis with advanced wavelet time-frequency analyses. Variance component analysis was used to evaluate the drivers of variance attributable to each experimental variable for each lymphangiography measurement type. Generalizability studies were used to assess the reliability of measured parameters and how reliability improves as the number of repeat measurements per subject increases. This allowed us to determine the minimum number of repeat measurements needed per subject for acceptable measurement reliability. This approach not only offers detailed insights into lymphatic pumping behaviors across species, sex and age, but also significantly boosts the reliability of these measurements by incorporating multiple regions of interest and evaluating the lymphatic system under various gravitational loads. For example, the reliability of the peak-and-valley analysis of human lymphatic vessels was increased 3-fold using the described approach. By addressing the critical need for improved imaging and quantification methods, our study offers a new standard approach for the imaging and analysis of lymphatic function that can improve our understanding, diagnosis, and treatment of lymphatic diseases. The results highlight the importance of comprehensive data acquisition strategies to fully capture the dynamic behavior of the lymphatic system.

Label-free optical microscopy utilizes the information encoded in light scattered off unlabeled particles to generate the images. This review article starts off with a discussion on how this light matter interaction gives rise to the issues of poor-contrast and diffraction-limited spatial resolution. Then, this article reviews the various far-field label-free optical microscopy techniques that have been developed, with an emphasis on the physical mechanisms behind the image formation processes in such techniques. Thus the article aims to elucidate the various state-of-the-art label-free techniques and their current applications.

Molecular imaging is used in clinical and research settings. Since tools to study viral pathogenesis longitudinally and systemically are limited, molecular imaging is an attractive and largely unexplored tool. This review discusses molecular imaging probes and techniques for studying viruses, particularly those currently used in oncology that are applicable to virology. Expanding the repertoire of probes to better detect viral disease may make imaging even more valuable in (pre-)clinical settings.

Pneumonia is a common infection in people suffering with Alzheimer's disease, leading to delirium, critical illness or severe neurological decline, which may be due to an amplified response of the blood-brain barrier (BBB) to peripheral insult. We assess the response of the BBB to repeated Streptococcus pneumoniae lung infection in rat model of Alzheimer's disease (TgF344-AD), at 13- and 18-months old, using dynamic contrast-enhanced (DCE) MRI and filter exchange imaging. Higher BBB water exchange rate is initially detected in infected TgF344-AD rats. BBB water exchange rates correlated with hippocampus aquaporin-4 water channel expression in infected animals. We detected no differences in BBB permeability to gadolinium contrast agent measured by DCE-MRI, confirmed by staining for tight junction proteins, occludin and claudin-5. These findings provide insight into the mechanisms of how peripheral inflammation impacts the BBB.

Given the enormous output and pace of development of artificial intelligence (AI) methods in medical imaging, it can be challenging to identify the true success stories to determine the state-of-the-art of the field. This report seeks to provide the magnetic resonance imaging (MRI) community with an initial guide into the major areas in which the methods of AI are contributing to MRI in oncology. After a general introduction to artificial intelligence, we proceed to discuss the successes and current limitations of AI in MRI when used for image acquisition, reconstruction, registration, and segmentation, as well as its utility for assisting in diagnostic and prognostic settings. Within each section, we attempt to present a balanced summary by first presenting common techniques, state of readiness, current clinical needs, and barriers to practical deployment in the clinical setting. We conclude by presenting areas in which new advances must be realized to address questions regarding generalizability, quality assurance and control, and uncertainty quantification when applying MRI to cancer to maintain patient safety and practical utility.

Senescent cells promote osteoarthritis progression through the secretion of inflammatory mediators. Preclinical studies have identified senescence-associated beta-galactosidase (β-gal) as a biomarker of senescence, but in vivo detection remains challenging. Here, we evaluated whether a β-gal responsive gadolinium (Gd) chelate can non-invasively detect β-gal expressing senescent cells with standard clinical magnetic resonance imaging (MRI) technology in vitro, ex vivo, and in vivo in porcine joints. In vitro studies showed that senescent mesenchymal stromal cells (MSCs) exhibited significant MRI signal enhancement upon incubation with the β-gal responsive Gd-chelate compared to viable control cells. In vivo, intraarticular injection of the probe into pig knee joints revealed its retention and activation by senescent cells in cartilage defects, evidenced by a significant increase in R ₁ relaxation rate. MRI-based senescent cell detection holds promise for identifying patients amenable to senolytic therapies, tailoring treatment plans, and monitoring therapy response in real-time.

The accurate measurement of three-dimensional (3D) fiber orientation in the brain is crucial for reconstructing fiber pathways and studying their involvement in neurological diseases. Comprehensive reconstruction of axonal tracts and small fascicles requires high-resolution technology beyond the ability of current in vivo imaging (e.g., diffusion magnetic resonance imaging). Optical imaging methods such as polarization-sensitive optical coherence tomography (PS-OCT) can quantify fiber orientation at micrometer resolution but have been limited to two-dimensional in-plane orientation, preventing the comprehensive study of connectivity in 3D. In this work we present a novel method to quantify volumetric 3D orientation in full angular space with PS-OCT in postmortem human brain tissues. We measure the polarization contrasts of the brain sample from two illumination angles of 0 and 15° and apply a computational method that yields the 3D optic axis orientation and true birefringence. We further present 3D fiber orientation maps of entire coronal cerebrum sections and brainstem with 10 μm in-plane resolution, revealing unprecedented details of fiber configurations. We envision that our method will open a promising avenue towards large-scale 3D fiber axis mapping in the human brain as well as other complex fibrous tissues at microscopic level.