Tissue Imaging Techniques Research Articles

Novel imaging and biophysical approaches to study tissue hydraulics in mammalian folliculogenesis

AbstractA key developmental stage in mammalian folliculogenesis is the formation of a fluid-filled lumen (antrum) prior to ovulation. While it has long been speculated that the follicular fluid is essential for oocyte maturation and ovulation, little is known about the morphogenesis and the mechanisms driving the antrum formation and ovulation, potentially due to challenges in imaging tissue dynamics in large tissues. Misregulation of such processes leads to anovulation, a hallmark of infertility in ageing and diseases such as the polycystic ovary syndrome (PCOS). In this review, we discuss recent advances in deep tissue imaging techniques, machine learning and theoretical approaches that have been applied to study development and diseases. We propose that an integrative approach combining these techniques is essential for understanding the physics of hydraulics in follicle development and ovarian functions.

Tissue Imaging Technique Using Near-Infrared Illumination of Whispering Gallery Mode Silicon-Based Resonator

Tissue Imaging Technique Using Near-Infrared Illumination of Whispering Gallery Mode Silicon-Based Resonator

The deterioration of microstructure and biochemical components in cancellous bone characterizing by the photoacoustic microscopy imaging

Abstract Background/Objective: Osteoporosis is mainly characterized by a deterioration of microstructure and a loss of biochemical components in bone tissues. Developing an imaging technique for measuring bone tissue microstructure and the biochemical components is of great significance for the early diagnosis of osteoporosis. Photoacoustic microscopy (PAM) has the advantage of high optical resolution and the potential to diagnose osteoporosis. In this study, we investigated the feasibility of the photoacoustic microscopy (PAM) technique for bone tissue imaging, and the deterioration of microstructure and biochemical components in cancellous bone was characterized by the PAM. Statement of Contribution/Methods: We performed the optical-resolution photoacoustic microscopy (OR-PAM) for bone tissue imaging and the trabecular microstructure and hydroxyapatite (HAP) were degraded by immersion in JYBL-I solution. The PAM imaging method was developed for the measurement of the surface and subsurface of cancellous bone with a high resolution. Specifically, a 532 nm pulse laser was used to excite the PA signal from the bone. The PA signal sampling frequency was 80 MHz. A motor rotated a 15 MHz central frequency transducer to receive 1000 × 1000 × 250 points data. The envelope of the signal was obtained using the Hilbert transform for reconstruction. Then, the JYBL-I solution was used to reduce the HAP component in the bone. The PAM imaging was performed after different immersion times, (i.e., at 0, 5, and 10 mins). In the PAM measurement of the cancellous bone, the imaging area was a cylinder with an 8 mm diameter and an 8 μm/pixel resolution. Results/Discussion: The results showed that the trabecular microstructure could be imaged with a relatively high quality using the PAM technique. With the different extent of HAP degradation by immersion in JYBL-I solution, some trabecular bone disappeared corresponding with PA signals decreased significantly in amplitude. Conclusion: These results indicate that the PA technique has potential application in the characterization of bone microstructure and biochemical components with a high resolution.

High-speed light-sheet fluorescent microscopy with an adaptive three-dimensional region-of-signal identification method

Light-sheet fluorescent microscopy (LSFM) is a crucial 3D imaging technique for tissues with advantages in high 3D spatial resolution, effective optical sectioning, and quick imaging. Prior to imaging, the sample's imaging depth, imaging region, and region of interest (ROI) division should all be established in accordance with the sample's outermost dimensions. However, because biological samples are inherently irregular a traditional imaging flow that images ROI by ROI, slice by slice, would waste a great deal of time and data storage space by additionally recording non-signal regions. In order to solve this problem, we create a high-speed LSFM with an adaptive three-dimensional region-of-signal identification method (RSI). We immediately perform crude imaging for each ROI before the software analyzes the longitudinal distribution and, ultimately, uses dimensionality reduction, binarization, filtering, and redundancy expansion to acquire the signal region result. By imaging two mouse spinal cord segments with a total of 170 ROIs and 180 ROIs on two channels, respectively, the high-speed imaging capability is validated. Our method reduced the overall imaging time and raw data size by more than treble and 14 times, respectively, without losing signal. With a programmable imaging range based on the real signal region, this method offers an efficient tool for flexible light-sheet microscopy. It can also be applied to other microscopy techniques to speed up imaging.

The guardians of pulmonary harmony: alveolar macrophages orchestrating the symphony of lung inflammation and tissue homeostasis.

Recent breakthroughs in single-cell sequencing, advancements in cellular and tissue imaging techniques, innovations in cell lineage tracing, and insights into the epigenome collectively illuminate the enigmatic landscape of alveolar macrophages in the lung under homeostasis and disease conditions. Our current knowledge reveals the cellular and functional diversity of alveolar macrophages within the respiratory system, emphasising their remarkable adaptability. By synthesising insights from classical cell and developmental biology studies, we provide a comprehensive perspective on alveolar macrophage functional plasticity. This includes an examination of their ontology-related features, their role in maintaining tissue homeostasis under steady-state conditions and the distinct contribution of bone marrow-derived macrophages (BMDMs) in promoting tissue regeneration and restoring respiratory system homeostasis in response to injuries. Elucidating the signalling pathways within inflammatory conditions, the impact of various triggers on tissue-resident alveolar macrophages (TR-AMs), as well as the recruitment and polarisation of macrophages originating from the bone marrow, presents an opportunity to propose innovative therapeutic approaches aimed at modulating the equilibrium between phenotypes to induce programmes associated with a pro-regenerative or homeostasis phenotype of BMDMs or TR-AMs. This, in turn, can lead to the amelioration of disease outcomes and the attenuation of detrimental inflammation. This review comprehensively addresses the pivotal role of macrophages in the orchestration of inflammation and resolution phases after lung injury, as well as ageing-related shifts and the influence of clonal haematopoiesis of indeterminate potential mutations on alveolar macrophages, exploring altered signalling pathways and transcriptional profiles, with implications for respiratory homeostasis.

T1 Mapping in Cardiovascular Magnetic Resonance-A Marker of Diffuse Myocardial Fibrosis in Patients Undergoing Hematopoietic Stem Cell Transplantation.

Introduction: Hematopoietic stem cell transplantation (HSCT) recipients are at increased risk of cardiovascular diseases. In our study, we aimed to find subclinical changes in myocardial tissue after HSCT with the help of cardiovascular magnetic resonance (CMR) tissue imaging techniques. Methods: The data of 44 patients undergoing autologous and allogeneic HSCT in the Hospital of Lithuanian University of Health Sciences Kaunas Clinics from October 2021 to February 2023 were analyzed. Bioethics approval for the prospective study was obtained (No BE-2-96). CMR was performed two times: before enrolling for the HSCT procedure (before starting mobilization chemotherapy for autologous HSCT and before starting the conditioning regimen for allogeneic HSCT) and 12 ± 1 months after HSCT. LV end-diastolic volume, LV end-systolic volume, LV mass and values indexed to body surface area (BSA), and LV ejection fraction were calculated. T1 and T2 mapping values were measured. Results: There was a statistically significant change in T1 mapping values. Before HSCT, mean T1 mapping was 1226.13 ± 39.74 ms, and after HSCT, it was 1248.70 ± 41.07 ms (p = 0.01). The other parameters did not differ significantly. Conclusions: Increases in T1 mapping values following HSCT can show the progress of diffuse myocardial fibrosis and may reflect subclinical injury. T2 mapping values remain the same and do not show edema and active inflammation processes at 12 months after HSCT.

Abstract B017: Understanding the impact of transporter heterogeneity on the efficacy of PARP inhibitors

Abstract B017: Understanding the impact of transporter heterogeneity on the efficacy of PARP inhibitors

Recent Developments and Application of Mass Spectrometry Imaging in N-Glycosylation Studies: An Overview.

Among the most typical posttranslational modifications is glycosylation, which often involves the covalent binding of an oligosaccharide (glycan) to either an asparagine (N-linked) or a serine/threonine (O-linked) residue. Studies imply that the N-glycan portion of a glycoprotein could serve as a particular disease biomarker rather than the protein itself because N-linked glycans have been widely recognized to evolve with the advancement of tumors and other diseases. N-glycans found on protein asparagine sites have been especially significant. Since N-glycans play clearly defined functions in the folding of proteins, cellular transport, and transmission of signals, modifications to them have been linked to several illnesses. However, because these N-glycans' production is not template driven, they have a substantial morphological range, rendering it difficult to distinguish the species that are most relevant to biology and medicine using standard techniques. Mass spectrometry (MS) techniques have emerged as effective analytical tools for investigating the role of glycosylation in health and illness. This is due to developments in MS equipment, data collection, and sample handling techniques. By recording the spatial dimension of a glycan's distribution in situ, mass spectrometry imaging (MSI) builds atop existing methods while offering added knowledge concerning the structure and functionality of biomolecules. In this review article, we address the current development of glycan MSI, starting with the most used tissue imaging techniques and ionization sources before proceeding on to a discussion on applications and concluding with implications for clinical research.

Recurrence of a Desmoid Tumour in a Scar at the Donor Site of a Latissimus Dorsi Flap

A desmoid tumour, also known as aggressive fibrous tumour or desmoid fibromatosis, is a rare, benign tumour originating from connective tissue cells. Desmoid tumours account for approximately 0.03+% of all neoplasms and less than 3+% of all soft tissue tumours. The estimated incidence in the general population is 2 to 4 cases per million people per year [1]. Desmoid tumours are characterised by aggressive growth but typically do not metastasize. They often occur in young adults and preferably affect specific body regions such as the abdomen, shoulder, chest, or extremities. The exact cause of the condition is not fully understood, but genetic changes and hormonal factors may play a role. Symptoms of a desmoid tumour depend on its location and size, with pain, swelling, or restricted movement commonly occurring. A diagnosis is typically made through a tissue sample (biopsy) and imaging techniques such as MRI or CT [2]. To our knowledge, this is the first documented case of recurrence of a desmoid tumour in the scar at the donor site of a latissimus dorsi flap previously used for the reconstruction of desmoid resection in the lower leg.

Sine Spin flat detector CT can improve cerebral soft tissue imaging: a retrospective in vivo study

BackgroundFlat detector computed tomography (FDCT) is frequently applied for periinterventional brain imaging within the angiography suite. Novel technical developments such as the Sine Spin FDCT (S-FDCT) may provide an improved cerebral soft tissue contrast. This study investigates the effect of S-FDCT on the differentiation between gray and white matter compared to conventional FDCT (C-FDCT) and multidetector computed tomography (MDCT).MethodsA retrospective analysis of a prospectively maintained patient database was performed, including patients who underwent mechanical thrombectomy in our institution and received S-FDCT or C-FDCT as well as MDCT. Differentiation between gray and white matter on the contralateral hemisphere to the ischemic stroke was analyzed quantitatively by contrast-to-noise ratio (CNR) and qualitatively (5-point ordinal scale).ResultsIn a cohort of 109 patients, MDCT demonstrated the best differentiation between gray and white matter compared to both FDCT techniques (p ≤ 0.001). Comparing both generations of FDCT, S-FDCT provided better visibility of the basal ganglia (p = 0.045) and the supratentorial cortex (p = 0.044) compared to C-FDCT both in quantitative and qualitative analyses. Median CNR were as follows: S-FDCT 2.41 (interquartile range [IQR] 1.66–3.21), C-FDCT 0.96 (0.46–1.70), MDCT 3.43 (2.83–4.17). For basal ganglia, median score and IQR were as follows: S-FDCT 2.00 (2.00–3.00), C-FDCT 1.50 (1.00–2.00), MDCT 5.00 (4.00–5.00).ConclusionsThe novel S-FDCT improves the periinterventional imaging quality of cerebral soft tissue compared to C-FDCT. Thus, it may improve the diagnosis of complications within the angiography suite. MDCT provides the best option for x-ray-based imaging of the brain tissue.Relevance statementFlat detector computed tomography is a promising technique for cerebral soft tissue imaging, while the novel Sine Spin flat detector computed tomography technique improves imaging quality compared to conventional flat detector computed tomography and thus may facilitate periinterventional diagnosis of gray and white matter.Key points• Flat detector computed tomography (FDCT) is frequently applied for periinterventional brain imaging.• The potential of novel Sine Spin FDCT (S-FDCT) is unknown so far.• S-FDCT improves the visibility of cerebral soft tissue compared to conventional FDCT.• Multidetector computed tomography is superior to both FDCT techniques.• S-FDCT may facilitate the evaluation of brain parenchyma within the angiography suite.Graphical

Deep learning of cell spatial organizations identifies clinically relevant insights in tissue images

Recent advancements in tissue imaging techniques have facilitated the visualization and identification of various cell types within physiological and pathological contexts. Despite the emergence of cell-cell interaction studies, there is a lack of methods for evaluating individual spatial interactions. In this study, we introduce Ceograph, a cell spatial organization-based graph convolutional network designed to analyze cell spatial organization (for example,. the cell spatial distribution, morphology, proximity, and interactions) derived from pathology images. Ceograph identifies key cell spatial organization features by accurately predicting their influence on patient clinical outcomes. In patients with oral potentially malignant disorders, our model highlights reduced structural concordance and increased closeness in epithelial substrata as driving features for an elevated risk of malignant transformation. In lung cancer patients, Ceograph detects elongated tumor nuclei and diminished stroma-stroma closeness as biomarkers for insensitivity to EGFR tyrosine kinase inhibitors. With its potential to predict various clinical outcomes, Ceograph offers a deeper understanding of biological processes and supports the development of personalized therapeutic strategies.

Speckle-Reduced Optical Coherence Tomography Using a Tunable Quasi-Supercontinuum Source

Optical coherence tomography (OCT), which has long been used for fine-scale structure imaging with higher resolution, larger penetration depth, and more detailed information, is a fast-growing technique for biological tissue imaging. However, speckle is an inherent property in OCT, appearing as bright and dark granular patterns, and hinders the visibility of the fine-scale structure. For the first time, we demonstrated speckle-reduced high-resolution imaging using a tunable quasi-supercontinuum (SC) source. OCT images with uncorrelated speckle patterns could be obtained by several quasi-SC spectra and compounded to improve the image quality. We confirmed that the implementation of a quasi-SC source enables us to reduce speckle noise for better observation of fine-scale structure.

RaMALDI: Enabling simultaneous Raman and MALDI imaging of the same tissue section

Multimodal tissue imaging techniques that integrate two complementary modalities are powerful discovery tools for unraveling biological processes and identifying biomarkers of disease. Combining Raman spectroscopic imaging (RSI) and matrix-assisted laser-desorption/ionization (MALDI) mass spectrometry imaging (MSI) to obtain fused images with the advantages of both modalities has the potential of providing spatially resolved, sensitive, specific biomolecular information, but has so far involved two separate sample preparations, or even consecutive tissue sections for RSI and MALDI MSI, resulting in images with inherent disparities. We have developed RaMALDI, a streamlined, integrated, multimodal imaging workflow of RSI and MALDI MSI, performed on a single tissue section with one sample preparation protocol. We show that RaMALDI imaging of various tissues effectively integrates molecular information acquired from both RSI and MALDI MSI of the same sample, which will drive discoveries in cell biology, biomedicine, and pathology, and advance tissue diagnostics.

JOINT MOTION CORRECTION AND 3D SEGMENTATION WITH GRAPH-ASSISTED NEURAL NETWORKS FOR RETINAL OCT.

Optical Coherence Tomography (OCT) is a widely used non-invasive high resolution 3D imaging technique for biological tissues and plays an important role in ophthalmology. OCT retinal layer segmentation is a fundamental image processing step for OCT-Angiography projection, and disease analysis. A major problem in retinal imaging is the motion artifacts introduced by involuntary eye movements. In this paper, we propose neural networks that jointly correct eye motion and retinal layer segmentation utilizing 3D OCT information, so that the segmentation among neighboring B-scans would be consistent. The experimental results show both visual and quantitative improvements by combining motion correction and 3D OCT layer segmentation comparing to conventional and deep-learning based 2D OCT layer segmentation.

The Desmoplastic Stroma of Pancreatic Cancer: Multilayered Levels of Heterogeneity, Clinical Significance, and Therapeutic Opportunities

Simple SummaryPancreatic cancer is a highly malignant disease with treatment resistance to standardized chemotherapies. In addition, only a small fraction of patients with pancreatic cancer has, to date, actionable genetic aberrations, leading to a narrow therapeutic window for molecularly targeted therapies or immunotherapies. A lot of preclinical and translational studies are ongoing to discover potential vulnerabilities to treat pancreatic cancer. Histologically, human pancreatic cancer is characterized by abundant cancer-associated fibrotic stroma, called “desmoplastic stroma”. Recent technological advances have revealed that desmoplastic stroma in pancreatic cancer is much more complicated than previously thought, playing pleiotropic roles in manipulating tumor cell fate and anti-tumor immunity. Moreover, real-world specimen-based analyses of pancreatic cancer stroma have also uncovered spatial heterogeneity and an intertumoral variety associated with molecular alterations, clinicopathological factors, and patient outcomes. This review describes an overview of the current efforts in the field of pancreatic cancer stromal biology and discusses treatment opportunities of stroma-modifying therapies against this hard-to-treat cancer.Pancreatic cancer remains one of the most lethal malignancies and is becoming a dramatically increasing cause of cancer-related mortality worldwide. Abundant desmoplastic stroma is a histological hallmark of pancreatic ductal adenocarcinoma. Emerging evidence suggests a promising therapeutic effect of several stroma-modifying therapies that target desmoplastic stromal elements in the pancreatic cancer microenvironment. The evidence also unveils multifaceted roles of cancer-associated fibroblasts (CAFs) in manipulating pancreatic cancer progression, immunity, and chemotherapeutic response. Current state-of-the-art technologies, including single-cell transcriptomics and multiplexed tissue imaging techniques, have provided a more profound knowledge of CAF heterogeneity in real-world specimens from pancreatic cancer patients, as well as in genetically engineered mouse models. In this review, we describe recent advances in the understanding of the molecular pathology bases of pancreatic cancer desmoplastic stroma at multilayered levels of heterogeneity, namely, (1) variations in cellular and non-cellular members, including CAF subtypes and extracellular matrix (ECM) proteins; (2) geographical heterogeneity in relation to cell–cell interactions and signaling pathways at niche levels and spatial heterogeneity at locoregional levels or organ levels; and (3) intertumoral stromal heterogeneity at individual levels. This review further discusses the clinicopathological significance of desmoplastic stroma and the potential opportunities for stroma-targeted therapies against this lethal malignancy.

A Short Review of Deep Tissue Imaging Techniques and Applications

Deep tissue imaging is a fundamental research method in the field of biological imaging. With an intent on obtaining more clear and detailed images deep within tissue, researchers have put much focus on developing deep tissue imaging techniques. In the past few decades, deep tissue imaging techniques have been improved in many aspects. In contrast to increasingly refined techniques, the application of these techniques seems to have not received equally attention. In this review, we will focus on the advanced applications of deep issue imaging that have emerged in recent years.

Discontinuously Dewetting Solvent Arrays: Droplet Formation and Poly-Synchronous Surface Extraction for Mass Spectrometry Imaging Applications.

We describe a new liquid tissue stamping method called poly-synchronous surface extraction (PSSE) that utilizes an omniphobic substrate patterned with hydrophilic surface energy traps (SETs), which when wet with a solvent form a dense microdroplet array. When contacted with a tissue sample, each droplet locally extracts analytes from the tissue surface, which subsequentially can be analyzed by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-IMS) or ambient ionization-MS techniques. Optimization of the patterned surface with six different solvents was carried out to increase the droplet density, height, and reproducibility of volume deposition. Once optimized, sister slices of a strawberry (Fragaria × ananassa) were spatially extracted using the PSSE technique and the chemical distribution of selected compounds was analyzed with both MALDI-IMS and a lower resolution but faster ambient liquid microjunction surface sampling probe (LMJ-SSP) approach. Heat maps for target analytes for the PSSE approach are compared to those produced using traditional MALDI-IMS analysis. The PSSE method aligned well with direct analysis and demonstrated the potential to increase the speed of ambient MS tissue imaging techniques by decreasing the number of steps required for sample preparation.

CLARITY techniques based tissue clearing: types and differences.

CLARITY is a tissue imaging technique that uses hydrogel embedded tissue to remove lipids while maintaining the intactness of protein and tissue fine structure. CLARITY has been widely used in the field of three-dimensional reconstruction of intact tissues and biomolecular information analysis, which enhances the ability to obtain biological structural and molecular information from intact systems. Therefore, many modified tissue clearing methods based on CLARITY have emerged. However, the variety and complexity of modified CLARITY techniques, as well as such challenges as low tissue clearing efficiency, tissue damage, and expensive experimental equipment significantly limited popular application. This review systematically summarises the progress of CLARITY techniques from the perspective of tissue clearing and classifies them into active CLARITY, passive CLARITY, and the method of merging active CLARITY with passive CLARITY according to different tissue clearing methods, which helps researchers to select a suitable tissue clearing method for the experimental samples more quickly and effectively based on balancing the removal speed and tissue transparency of different tissue clearing methods. In addition, combing through the advantage and highlighting the limitations of CLARITY techniques may be beneficial for the ideas building of different research and enlighten to improve the details of the techniques.

Recent progress in optical clearing of eye tissues

The growing need for viewing the detailed 3D structures of various tissues and organs requires advanced tissue processing and imaging techniques. However, light scattering by tissues hinders detailed structural observations. To overcome this, the emerging technique of “tissue optical clearing” has been flourishing in recent decades, providing excellent opportunities for imaging deep, micro-scale structures of various organs, or even of the whole body. In recent years, advanced tissue clearing techniques have been optimized for specific tissues and organs. Among these tissues, the eye is unique owing to its delicate structure and pigmented retinal epithelial cells, calling for more work on making these tissues “transparent”. In this review, we searched Medline and Embase for studies published between January 2006 and August 2021 using the terms “tissue optical clearing”, “ophthalmology”, “eye”, and “optical clearing agents”, and we reviewed the publications on the optical clearing techniques of eye tissue from 2006 to the present, including both the clearing procedures and the subsequent analytical processes, thus gaining more insight into the application of tissue optical clearing in basic eye research. Furthermore, we discuss the future potential of optical clearing applications in clinical ophthalmology.

Prediction of pancreatic fistula after pancreatectomy by virtual touch tissue imaging and quantification (VTIQ) technology

ObjectivesThe aim of this study was to quantitatively evaluate the stiffness of pancreatic parenchyma and solid focal pancreatic lesions (FPLs) by virtual touch tissue imaging and quantification (VTIQ) technique and to investigate the potential usefulness of VTIQ method in the prediction of post-operative pancreatic fistula (POPF) after pancreatectomy. MethodsIn this prospective study, patients who scheduled to undergo pancreatectomy were initially enrolled and received VTIQ assessment within one week before surgery. VTIQ elastography (Siemens ACUSON Sequoia, 5C-1 transducer) was used to measure the shear wave velocity (SWV) value of FPLs and the body part pancreatic parenchyma. The palpation stiffness of pancreas was qualitatively evaluated during operation by surgeons. POPF was finally diagnosed and graded through a three-weeks post-operative follow-up according to international study group of pancreatic fistula (ISGPF). SWV values were compared between POPF positive and negative group. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic efficacy of SWV value in predicting POPF. ResultsFrom December 2020 to June 2021, 44 patients were finally enrolled in this study, among which, 26 patients were identified to develop POPF after pancreatectomy. The SWV value of pancreatic parenchyma in POPF positive group was significantly lower than that in POPF negative group (P = 0.001). However, there was no significant difference in palpation stiffness between the two groups (P = 0.124). Besides, neither the SWV value of FPL nor the SWV ratio between FPL to surrounding pancreatic parenchyma differ significantly between POPF positive and negative group (P > 0.05). Taking SWV value of pancreatic parenchyma >1.10 m/s as a cut-off value for predicting POPF, area under the receiver operating characteristic curve (AUROC) was 0.864 with 72.2% sensitivity, 92.3% specificity, 86.7% positive predictive value (PPV) and 82.8% negative predictive value (NPV), respectively. ConclusionsVTIQ technique might be a potential non-invasive imaging method to predict POPF before pancreatectomy in future clinical practice.