The Role of Micro-CT in 3D Histology Imaging

Microcomputed tomography as a diagnostic tool for detection of lymph node metastasis in non-small cell lung cancer: A decision-support approach for pathological examination "A pilot study for method validation"

Background

Non-small cell lung cancer (NSCLC) patients without lymph node (LN) metastases (pN0) may exhibit different survival rates, even when their T stage is similar. This divergence could be attributed to the current pathology practice, wherein LNs are examined solely in two-dimensional (2D). Unfortunately, adhering to the protocols of 2D pathological examination does not ensure the exhaustive sampling of all excised LNs, thereby leaving room for undetected metastatic foci in the unexplored depths of tissues. The employment of micro-computed tomography (micro-CT) facilitates a three-dimensional (3D) evaluation of all LNs without compromising sample integrity. In our study, we utilized quantitative micro-CT parameters to appraise the metastatic status of formalin-fixed paraffin-embedded (FFPE) LNs.

Methods

Micro-CT scans were conducted on 12 FFPEs obtained from 8 NSCLC patients with histologically confirmed mediastinal LN metastases. Simultaneously, whole-slide images from these FFPEs underwent scanning, and 47 regions of interest (ROIs) (17 metastatic foci, 11 normal lymphoid tissues, 10 adipose tissues, and 9 anthracofibrosis) were marked on scanned images. Quantitative structural variables obtained via micro-CT analysis from tumoral and non-tumoral ROIs, were analyzed.

Result

Significant distinctions were observed in linear density, connectivity, connectivity density, and closed porosity between tumoral and non-tumoral ROIs, as indicated by kappa coefficients of 1, 0.90, 1, and 1, respectively. Receiver operating characteristic analysis substantiated the differentiation between tumoral and non-tumoral ROIs based on thickness, linear density, connectivity, connectivity density, and the percentage of closed porosity.

Conclusions

Quantitative micro-CT parameters demonstrate the ability to distinguish between tumoral and non-tumoral regions of LNs in FFPEs. The discriminatory characteristics of these quantitative micro-CT parameters imply their potential usefulness in developing an artificial intelligence algorithm specifically designed for the 3D identification of LN metastases while preserving the FFPE tissue.

3D Virtual Histopathology by Phase-Contrast X-Ray Micro-CT for Follicular Thyroid Neoplasms

Histological analysis is the core of follicular thyroid carcinoma (FTC) classification. The histopathological criteria of capsular and vascular invasion define malignancy and aggressiveness of FTC. Analysis of multiple sections is cumbersome and as only a minute tissue fraction is analyzed during histopathology, under-sampling remains a problem. Application of an efficient tool for complete tissue imaging in 3D would speed-up diagnosis and increase accuracy. We show that X-ray propagation-based imaging (XPBI) of paraffin-embedded tissue blocks is a valuable complementary method for follicular thyroid carcinoma diagnosis and assessment. It enables a fast, non-destructive and accurate 3D virtual histology of the FTC resection specimen. We demonstrate that XPBI virtual slices can reliably evaluate capsular invasions. Then we discuss the accessible morphological information from XPBI and their significance for vascular invasion diagnosis. We show 3D morphological information that allow to discern vascular invasions. The results are validated by comparing XPBI images with clinically accepted histology slides revised by and under supervision of two experienced endocrine pathologists.

3D visualization and printing: An "Anatomical Engineering" trend revealing underlying morphology via innovation and reconstruction towards future of veterinary anatomy

The amalgamation of veterinary anatomy, technology and innovation has led to development of latest technological advancement in the field of veterinary medicine, i.e., three-dimensional (3D) imaging and reconstruction. 3D visualization technique followed by 3D reconstruction has been proven to enhance non-destructive 3D visualization grossly or microscopically, e.g., skeletal muscle, smooth muscle, ligaments, cartilage, connective tissue, blood vessels, nerves, lymph nodes, and glands. The core aim of this manuscript is to document non-invasive 3D visualization methods being adopted currently in veterinary anatomy to reveal underlying morphology and to reconstruct them by 3D softwares followed by printing, its applications, current challenges, trends and future opportunities. 3D visualization methods such as MRI, CT scans and micro-CT scans are utilised in revealing volumetric data and underlying morphology at microscopic levels as well. This will pave a way to transform and re-invent the future of teaching in veterinary medicine, in clinical cases as well as in exploring wildlife anatomy. This review provides novel insights into 3D visualization and printing as it is the future of veterinary anatomy, thus making it spread to become the plethora of opportunities for whole veterinary science.

Contrast-enhanced Micro-CT 3D visualization of cell distribution in hydrated human cornea

Background

The cornea, a vital component of the human eye, plays a crucial role in maintaining visual clarity. Understanding its ultrastructural organization and cell distribution is fundamental for elucidating corneal physiology and pathology. This study comprehensively examines the microarchitecture of the hydrated human cornea using contrast-enhanced micro-computed tomography (micro-CT).

Method

Fresh human corneal specimens were carefully prepared and hydrated to mimic their in vivo state. Contrast enhancement with Lugol's iodine-enabled high-resolution Micro-CT imaging. The cells' three-dimensional (3D) distribution within the cornea was reconstructed and analyzed.

Results

The micro-CT imaging revealed exquisite details of the corneal ultrastructure, including the spatial arrangement of cells throughout its depth. This novel approach allowed for the visualization of cells' density and distribution in different corneal layers. Notably, our findings highlighted variations in cell distribution between non-hydrated and hydrated corneas.

Conclusions

This study demonstrates the potential of contrast-enhanced micro-CT as a valuable tool for non-destructive, 3D visualization and quantitative analysis of cell distribution in hydrated human corneas. These insights contribute to a better understanding of corneal physiology and may have implications for research in corneal diseases and tissue engineering.

Multimodal exploration of the intracranial aneurysm wall

PURPOSE

Intracranial aneurysms (IAs) are pathological changes of the intracranial vessel wall, although clinical image data can only show the vessel lumen. Histology can provide wall information but is typically restricted to ex vivo 2D slices where the shape of the tissue is altered.

METHODS

We developed a visual exploration pipeline for a comprehensive view of an IA. We extract multimodal information (like stain classification and segmentation of histologic images) and combine them via 2D to 3D mapping and virtual inflation of deformed tissue. Histological data, including four stains, micro-CT data and segmented calcifications as well as hemodynamic information like wall shear stress (WSS), are combined with the 3D model of the resected aneurysm.

RESULTS

Calcifications were mostly present in the tissue part with increased WSS. In the 3D model, an area of increased wall thickness was identified and correlated to histology, where the Oil red O (ORO) stained images showed a lipid accumulation and the alpha-smooth muscle actin (aSMA) stained images showed a slight loss of muscle cells.

CONCLUSION

Our visual exploration pipeline combines multimodal information about the aneurysm wall to improve the understanding of wall changes and IA development. The user can identify regions and correlate how hemodynamic forces, e.g. WSS, are reflected by histological structures of the vessel wall, wall thickness and calcifications.

Multimodal CT imaging of ischemic stroke thrombi identifies scale-invariant radiomic features that reflect clot biology

BACKGROUND

Biological interpretability of ischemic stroke clot imaging remains challenging.

OBJECTIVE

To carry out paired CT/micro-CT imaging of ischemic stroke clots retrieved by thrombectomy with the aim of identifying interpretable image features that are correlated among pretreatment image modalities and post-treatment histopathology.

METHODS

We performed multimodal CT imaging and histology for 10 stroke clots retrieved by mechanical thrombectomy. Clots were manually segmented from co-registered, pretreatment CT angiography (CTA) and non-contrast CT (NCCT). For the same cases, retrieved clots were iodine-stained, and imaged with a ScanCo micro-CT 100 (4.9 µm resolution). Afterwards, clots were subjected to histological processing (hematoxylin and eosin staining) and whole slide scanned (40X). Clot radiomic features (RFs) (n=93 per modality, 279 total) were extracted using PyRadiomics and histological composition was computed using Orbit Image Analysis. Correlation analysis was used to test associations between micro-CT and CTA (or NCCT) RFs as well as between RFs and histological composition. Statistical significance was considered at R≥0.65 and q<0.05.

RESULTS

From paired RF correlation analysis, we identified 23 scale-invariant RFs with significant correlation between micro-CT and CTA (18), and micro-CT and NCCT (5). Correlation of unpaired RFs identified 377 positively and 36 negatively correlated RFs between micro-CT and CTA, and 168 positively and 41 negatively correlated RFs between micro-CT and NCCT. Scale-invariant RFs computed from CTA and NCCT demonstrated significant correlation with red blood cell and fibrin-platelet components, while micro-CT RFs were found to be correlated with white blood cell percent composition.

CONCLUSION

Multimodal CT, radiomic, and histological analysis of stroke clots can help to bridge the gap between pretreatment imaging and clot pathobiology.

Influence of antiresorptive/antiangiogenic therapy on changes in periodontal and oral tissue structures: a histomorphometrical analysis in rats

OBJECTIVE

The objective of this study was to investigate the influence of various antiresorptive and antiangiogenic medications on morphological changes in periodontal and oral tissue structures.

MATERIALS AND METHODS

Fifty-five Wistar rats randomly received dual application (i.e., at baseline and after 12-weeks) one of the following medications: (1) amino-bisphosphonate [zoledronate (Zo)], (2) RANKL inhibitor [denosumab (De)], (3) antiangiogenic [bevacizumab (Be)], (4) Zo + Be, (5) De + Be or (6) no medication [Control (Co)]. Periodontal and oral tissue biopsies were obtained at 17 (n = 21 animals, Phase 1, (De = 3, De + Be = 3, Zo = 5, Be = 3, Zo + Be = 2, Co = 5) and 29 (n = 34 animals, (De = 8, De + Be = 6, Zo = 2, Be = 7, Zo + Be = 4, Co = 7, Phase 2) weeks after the second drug application. The following outcomes were histomorphometrically assessed: periodontal space width in the coronal (PLS-C, mm) and apical sections (PLS- A), number of empty alveolar bone lacunae in the coronal, apical sections and at the apex at respective tooth sites (EL - C, EL- A, EL- Ap), mucosal thickness at edentulous alveolar ridge areas (MT, mm), and, when present, associated areas of inflammatory cell infiltrates (ICI, mm2).

RESULTS

Comparable mean PLS-C, PLS-A, ET-A, ET-C, ET-Ap, and MT values were observed in all experimental groups after Phases 1 and 2. The presence of ICI was identified in 3 animals in the Co group (Phase 1: 1, Phase 2: 2), and 17 animals in the test groups (Phase 1: 4; Phase 2: 14). The estimated ICI surface area was significantly higher in the Zo + Be group, followed by the Zo and Be groups compared to that measured in the Co group. The time (i.e., Phases 1 and 2) was not found to be a predictor for the extent of the ICI area. In all groups, the EL-C, EL-A, and EL-Ap values were significantly higher after Phase 2 compared to those assessed after Phase 1. The MT values were significantly reduced in all groups after Phase 2 compared to those measured after Phase 1.

CONCLUSIONS

The present evaluation was not able to find any morphological effects of different antiresorptive and antiangiogenic medications on periodontal and oral tissue structures. The presence of inflammatory cell infiltrates was more frequently observed in the animals administered with antiresorptive and antiangiogenic medications as well as combinations thereof.

CLINICAL RELEVANCE

Administration of antiresorptive and antiangiogenic medications may be capable of inducing inflammatory reactions in periodontal tissues.

Durability assessment of hydrogel mountings for contrast-enhanced micro-CT

Micro-computed tomography (micro-CT) provides valuable data for studying soft tissue, though it is often affected by sample movement during scans and low contrast in X-ray absorption. This can result in lower image quality and geometric inaccuracies, collectively known as 'artefacts'. To mitigate these issues, samples can be embedded in hydrogels and enriched with heavy metals for contrast enhancement. However, the long-term durability of these enhancements remains largely unexplored. In this study, we examine the effects of two contrast enhancement agents - iodine and phosphotungstic acid (PTA) - and two hydrogels - agarose and Poloxamer 407 - over a 14-day period. We used Drosophila melanogaster as a test model for our investigation. Our findings reveal that PTA and agarose are highly durable, while iodine and poloxamer hydrogel exhibits higher leakage rates. These observations lay the foundation for estimating contrast stabilities in contrast-enhanced micro-CT with hydrogel embedding and serve to inform future research in this field.

X-ray Stain Localization with Near-Field Ptychographic Computed Tomography

Although X-ray contrast agents offer specific characteristics in terms of targeting and attenuation, their accumulation in the tissue on a cellular level is usually not known and difficult to access, as it requires high resolution and sensitivity. Here, quantitative near-field ptychographic X-ray computed tomography is demonstrated to assess the location of X-ray stains at a resolution sufficient to identify intracellular structures by means of a basis material decomposition. On the example of two different X-ray stains, the nonspecific iodine potassium iodide, and eosin Y, which mostly interacts with proteins and peptides in the cell cytoplasm, the distribution of the stains within the cells in murine kidney samples is assessed and compared to unstained samples with similar structural features. Quantitative nanoscopic stain concentrations are in good agreement with dual-energy micro computed tomography measurements, the state-of-the-art modality for material-selective imaging. The presented approach can be applied to a variety of X-ray stains advancing the development of X-ray contrast agents.

An optimized workflow for microCT imaging of formalin‐fixed and paraffin‐embedded ( FFPE ) early equine embryos

Here, we describe a workflow for high‐detail microCT imaging of formalin‐fixed and paraffin‐embedded (FFPE) equine embryos recovered on Day 34 of pregnancy (E34), a period just before placenta formation. The presented imaging methods are suitable for large animals' embryos with intention to study morphological and developmental aspects, but more generally can be adopted for all kinds of FFPE tissue specimens. Microscopic 3D imaging techniques such as microCT are important tools for detecting and studying normal embryogenesis and developmental disorders. To date, microCT imaging of vertebrate embryos was mostly done on embryos that have been stained with an X‐ray dense contrast agent. Here, we describe an alternative imaging procedure that allows to visualize embryo morphology and organ development in unstained FFPE embryos. Two aspects are critical for high‐quality data acquisition: (i) a proper sample mounting leaving as little as possible paraffin around the sample and (ii) an image filtering pipeline that improves signal‐to‐noise ratio in these inherently low‐contrast data sets. The presented workflow allows overview imaging of the whole embryo proper and can be used for determination of organ volumes and development. Furthermore, we show that high‐resolution interior tomographies can provide virtual histology information from selected regions of interest. In addition, we demonstrate that microCT scanned embryos remain intact during the scanning procedure allowing for a subsequent investigation by routine histology and/or immunohistochemistry. This makes the presented workflow applicable also to archival paraffin‐embedded material.

Patch-based artifact reduction for three-dimensional volume projection data of sparse-view micro-computed tomography

Micro-computed tomography (micro-CT) enables the non-destructive acquisition of three-dimensional (3D) morphological structures at the micrometer scale. Although it is expected to be used in pathology and histology to analyze the 3D microstructure of tissues, micro-CT imaging of tissue specimens requires a long scan time. A high-speed imaging method, sparse-view CT, can reduce the total scan time and radiation dose; however, it causes severe streak artifacts on tomographic images reconstructed with analytical algorithms due to insufficient sampling. In this paper, we propose an artifact reduction method for 3D volume projection data from sparse-view micro-CT. Specifically, we developed a patch-based lightweight fully convolutional network to estimate full-view 3D volume projection data from sparse-view 3D volume projection data. We evaluated the effectiveness of the proposed method using physically acquired datasets. The qualitative and quantitative results showed that the proposed method achieved high estimation accuracy and suppressed streak artifacts in the reconstructed images. In addition, we confirmed that the proposed method requires both short training and prediction times. Our study demonstrates that the proposed method has great potential for artifact reduction for 3D volume projection data under sparse-view conditions.

MicroCT Can Characterize Clots Retrieved With Mechanical Thrombectomy From Acute Ischemic Stroke Patients–A Preliminary Report

Background

Characterization of the clot occluding the arteries in acute ischemic stroke received ample attention, in terms of elucidating the relationship between the clot composition, its etiology and its amenability for pharmacological treatment and mechanical thrombectomy approaches. Traditional analytical techniques such as conventional 2D histopathology or electron microscopy sample only small parts of the clot. Visualization and analysis in 3D are necessary to depict and comprehend the overall organization of the clot. The aim of this study is to investigate the potential of microCT for characterizing the clot composition, structure, and organization.

Methods

In a pilot study, we analyzed with microCT clots retrieved from 14 patients with acute ischemic stroke. The following parameters were analyzed: overall clot density, clot segmentation with various density thresholds, clot volume.

Results

Our findings show that human clots are heterogeneous in terms of CT intra-clot density distribution. After fixation in formalin, the clots display a shift toward negative values. On average, we found the mean HU values of red clots retrieved from patients to be −153 HU, with SD = 23.8 HU, for the intermediate clots retrieved from patients −193 HU, SD = 23.7 HU, and for the white clots retrieved from patients −229 HU, SD = 64.8 HU.

Conclusion

Our study shows that volumetric and density analysis of the clot opens new perspectives for clot characterization and for a better understanding of thrombus structure and composition.

Integration of multiple imaging platforms to uncover cardiovascular defects in adult zebrafish

Aims

Mammalian models have been instrumental in investigating adult heart function and human disease. However, electrophysiological differences with human hearts and high costs motivate the need for non-mammalian models. The zebrafish is a well-established genetic model to study cardiovascular development and function; however, analysis of cardiovascular phenotypes in adult specimens is particularly challenging as they are opaque.

Methods and results

Here, we optimized and combined multiple imaging techniques including echocardiography, magnetic resonance imaging, and micro-computed tomography to identify and analyse cardiovascular phenotypes in adult zebrafish. Using alk5a/tgfbr1a mutants as a case study, we observed morphological and functional cardiovascular defects that were undetected with conventional approaches. Correlation analysis of multiple parameters revealed an association between haemodynamic defects and structural alterations of the heart, as observed clinically.

Conclusion

We report a new, comprehensive, and sensitive platform to identify otherwise indiscernible cardiovascular phenotypes in adult zebrafish.

Multiscale imaging of the rat brain using an integrated diceCT and histology workflow

Advancements in tissue visualization techniques have spurred significant gains in the biomedical sciences by enabling researchers to integrate their datasets across anatomical scales. Of particular import are techniques that enable the interpolation of multiple hierarchical scales in samples taken from the same individuals. In this study, we demonstrate that two-dimensional histology techniques can be employed on neural tissues following three-dimensional diffusible iodine-based contrast-enhanced computed tomography (diceCT) without causing tissue degradation. This represents the first step toward a multiscale pipeline for brain visualization. We studied brains from adolescent male Sprague-Dawley rats, comparing experimental (diceCT-stained then de-stained) to control (without diceCT) brains to examine neural tissues for immunolabeling integrity, compare somata sizes, and distinguish neurons from glial cells within the telencephalon and diencephalon. We hypothesized that if experimental and control samples do not differ significantly in morphological cell analysis, then brain tissues are robust to the chemical, temperature, and radiation environments required for these multiple, successive imaging protocols. Visualizations for experimental brains were first captured via micro-computed tomography scanning of isolated, iodine-infused specimens. Samples were then cleared of iodine, serially sectioned, and prepared again using immunofluorescent, fluorescent, and cresyl violet labeling, followed by imaging with confocal and light microscopy, respectively. Our results show that many neural targets are resilient to diceCT imaging and compatible with downstream histological staining as part of a low-cost, multiscale brain imaging pipeline.

Development of Pathological Diagnosis Support System Using Micro-computed Tomography

In pathological diagnosis, the cutting position of pathological materials is subjectively determined by pathologists. This leads to a low cutting accuracy, which in turn may lead to incorrect diagnoses. In this study, we developed a system that supports the determination of the cutting position by visualizing and analyzing the internal structure of pathological material using micro-computed tomography (CT) before cutting. This system consists of a dedicated micro-CT and cutting support software. The micro-CT system has a fixture for fixing the target, enabling the scanning of easily deformable pathological materials. In the cutting support software, a function that interactively selects the extraction plane while displaying the volume rendering image and outputs a pseudo-histological image was implemented. Our results confirmed that the pseudo-histological image showed the fine structure inside the organ and that the latter image was highly consistent with the pathological image.

3D-Non-destructive Imaging through Heavy-Metal Eosin Salt Contrast Agents

Conventional histology is a destructive technique based on the evaluation of 2D slices of a 3D biopsy. By using 3D X‐ray histology these obstacles can be overcome, but their application is still restricted due to the inherently low attenuation properties of soft tissue. In order to solve this problem, the tissue can be stained before X‐ray computed tomography imaging (CT) to enhance the soft tissue X‐ray contrast. Evaluation of brominated fluorescein salts revealed a mutual influence of the number of bromine atoms and the cations applied on the achieved contrast enhancement. The dibromo fluorescein barium salt turned out to be the ideal X‐ray contrast agent, allowing for 3D imaging and subsequent complementing counterstaining applying standard histological techniques.

Differentiation of benign and malignant regions in paraffin embedded tissue blocks of pulmonary adenocarcinoma using micro CT scanning of paraffin tissue blocks: a pilot study for method validation

PURPOSE

Micro computed tomography (micro-CT) can provide detailed information about the internal structure of materials. This study aimed to demonstrate the diagnostic value of micro-CT in formalin fixed paraffin embedded pulmonary adenocarcinomas by correlating the micro-CT findings of tumoral and non-tumoral areas with hematoxylin and eosin (HE) sections.

METHODS

Paraffin blocks obtained from three adenocarcinomas were scanned with micro-CT. Ten regions of interest (ROIs) from adenocarcinoma and 11 ROIs from pulmonary parenchyma (ROI-C and ROI-N, respectively) areas were compared regarding the various structural parameters.

RESULTS

All parameters were significantly different regarding the tumoral and non-tumoral ROIs. The percent object volume, structure thickness, structure linear density, connectivity and connectivity density were higher in ROI-Cs (p < 0.000, p < 0.000, p = 0.001, p < 0.000, and p < 0.000 respectively); whereas intersection surface and structure model index were higher in ROI-Ns (p < 0.000 and p < 0.000). The open porosity percentage was higher in ROI-Ns (68.86 + 2.96 vs 48.29 + 5.11, p < 0.000) and the closed porosity percentage was higher in ROI-Cs (2.29 + 0.55 vs 0.57 + 0.17 p < 0.000).

CONCLUSIONS

The tumoral and non-tumoral areas in paraffin blocks can be distinguished from each other, using the quantitative and qualitative information obtained by micro-CT. Making this distinction with quantitative data obtained from micro-CT can therefore be the basis of creating artificial intelligence algorithms in the future.

Detection and assessment of capsular invasion, vascular invasion and lymph node metastasis volume in thyroid carcinoma using microCT scanning of paraffin tissue blocks (3D whole block imaging): a proof of concept

In the modern era, detailed pathologic characteristics of a thyroid tumor are crucial to achieve accurate diagnosis and guide treatment. The presence of capsular invasion (CI) is diagnostic for carcinoma, whereas vascular invasion (VI) and nodal metastasis (NM) are included in risk stratification. However, the very definition of CI and VI is surrounded by controversies and an accurate assessment of NM is lacking. Whole Block Imaging (WBI) by microCT is a new imaging modality to create 3D reconstruction of whole tissue block with microscopic level resolution without the need for tissue sectioning. In this study, we aimed to define CI, VI, and NM volume using WBI by microCT. Twenty-eight paraffin blocks (PBs) from 26 thyroid tumors were scanned. Ten PBs contained CI, whereas 7 had VI. 3D microCT images were compared with whole slide images (WSI) of corresponding H&E slides. In 2 cases with VI and/or CI, WSI of serial H&E slides were obtained and underwent 3D-reconstruction to be compared with the WBI. Satellite tumor nodules beyond tumor capsule were shown to be CI by demonstrating the point of penetration using microCT and 3D reconstruction. Additional foci of CI were detected using microCT. VI was seen using microCT. Fibrin associated with tumor thrombus was not always present on serially sectioned H&E slides. WBI by microCT scanner was able to assess the volume of NM. In conclusion, WBI is able to detect CI, VI, and assess the volume of NM in thyroid carcinoma without tissue sectioning. It is the ultimate method for the complete sampling of the tumor capsule. It has the potential to increase the detection rate of CI, better define criteria for CI and VI, and provide an accurate assessment of the volume of nodal disease. This technology may impact the future practice of surgical pathology.

Iodine-enhanced micro-computed tomography of atherosclerotic plaque morphology complements conventional histology

BACKGROUND AND AIMS

Visualization of arterial lesions in situ can enhance understanding of atherosclerosis progression and potentially improve experimental therapies. Conventional histology methods for assessing atherosclerotic lesions are robust but are destructive and may prevent further tissue analysis. The objective of the current study was to evaluate a novel, nondestructive method for visualization and characterization of atherosclerotic lesions as an alternative or complementary to routine histology. Thus, we tested the hypothesis that micro-computed tomography (micro-CT) paired with an iodine-based radiopaque stain would effectively characterize atherosclerotic plaques in a manner comparable to routine histology while maintaining sample integrity and providing whole-volume data.

METHODS

We examined porcine coronary arteries with varying degrees of atherosclerosis, using micro-CT in the absence and presence of iohexol (240 mgI/ml). Following iohexol washout, routine histological assessment of the samples was performed with hematoxylin and eosin and Masson's trichrome.

RESULTS

Iohexol staining generated soft tissue delineation and subsequent atherosclerotic plaque assessment via augmented radiopacity, permitting three-dimensional (3D) reconstruction of these lesions, maintaining in situ architecture. Although plaque distribution and arterial wall tissue layers were discernible, micro-CT was incapable of discriminating cell types comprising the plaque. Calcium phosphate deposition was readily located and visualized in 3D space, independent of iohexol.

CONCLUSIONS

The results of this study establish micro-CT, combined with a diffusible radiopaque contrast agent, as a powerful imaging modality for visualizing in situ architecture of atherosclerotic plaques. Our findings demonstrate that micro-CT can be used to identify plaque distribution and calcium deposition complementary to routine histological analysis.

Wear debris released by hip prosthesis analysed by microcomputed tomography

Total hip arthroplasty uses commercial devices that combine different types of biomaterials. Among them, metals, ceramics and metal oxides can be used either in the prosthesis itself or in the cement used to anchor them in the bone. Over time, all of these materials can wear out and release particles that accumulate in the periprosthetic tissues or can migrate away. We used histology blocks from 15 patients (5 titanium metallosis, 5 alumina prostheses, 5 with altered methacrylic cement) to perform a microCT study and compare it with conventional histology data. An EDS-SEM analysis was done to characterise the atomic nature of the materials involved. A morphometric analysis was also performed in 3D to count the particles and assess their density and size. The metallic particles appeared to be the largest and the ceramic particles the finest. However, microCT could not reveal the wear particles of radiolucent biomaterials such as polyethylene and the very fine zirconia particles from cement fragmentation. MicroCT analysis can reveal the extent of the accumulation of these debris in the periprosthetic tissues. LAYOUT DESCRIPTION: Hip prostheses progressively degrade in the body by releasing wear debris. They accumulate in the periprosthetic tissues. Microcomputed tomography was used to image three types of radio-opaque wear debris: metal, ceramic and zirconia used in the bone cements.

MicroCT optimisation for imaging fascicular anatomy in peripheral nerves

BACKGROUND

Due to the lack of understanding of the fascicular organisation, vagus nerve stimulation (VNS) leads to unwanted off-target effects. Micro-computed tomography (microCT) can be used to trace fascicles from periphery and image fascicular anatomy.

NEW METHOD

In this study, we present a simple and reproducible method for imaging fascicles in peripheral nerves with iodine staining and microCT for the determination of fascicular anatomy and organisation.

RESULTS

At the determined optimal pre-processing steps and scanning parameters, the microCT protocol allowed for segmentation and tracking of fascicles within the nerves. This was achieved after 24 hours and 120 hours of staining with Lugol's solution (1% total iodine) for rat sciatic and pig vagus nerves, respectively, and the following scanning parameters: 4 μm voxel size, 35 kVp energy, 114 μA current, 4 W power, 0.25 fps in 4 s exposure time, 3176 projections and a molybdenum target.

COMPARISON WITH EXISTING METHOD(S)

This optimised method for imaging fascicles provides high-resolution, three-dimensional images and full imaging penetration depth not obtainable with methods typically used such as histology, magnetic resonance imaging and optical coherence tomography whilst obviating time-consuming pre-processing methods, the amount of memory required, destruction of the samples and the cost associated with current microCT methods.

CONCLUSION

The optimised microCT protocol facilitates segmentation and tracking of the fascicles within the nerve. The resulting segmentation map of the functional anatomical organisation of the vagus nerve will enable selective VNS ultimately allowing for the avoidance of the off-target effects and improving its therapeutic efficacy.

The role of Micro-CT in imaging breast cancer specimens

PURPOSE

The goal of breast cancer surgery is to remove all of the cancer with a minimum of normal tissue, but absence of full 3-dimensional information on the specimen makes this difficult to achieve.

METHOD

Micro-CT is a high resolution, X-ray, 3D imaging method, widely used in industry but rarely in medicine.

RESULTS

We imaged and analyzed 173 partial mastectomies (129 ductal carcinomas, 14 lobular carcinomas, 28 DCIS). Imaging was simple and rapid. The size and shape of the cancers seen on Micro-CT closely matched the size and shape of the cancers seen at specimen dissection. Micro-CT images of multicentric/multifocal cancers revealed multiple non-contiguous masses. Micro-CT revealed cancer touching the specimen edge for 93% of the 114 cases judged margin positive by the pathologist, and 28 of the cases not seen as margin positive on pathological analysis; cancer occupied 1.55% of surface area when both the pathologist and Micro-CT suggested cancer at the edge, but only 0.45% of surface area for the "Micro-CT-Only-Positive Cases". Thus, Micro-CT detects cancers that touch a very small region of the specimen surface, which is likely to be missed on sectioning.

CONCLUSIONS

Micro-CT provides full 3D images of breast cancer specimens, allowing one to identify, in minutes rather than hours, while the patient is in OR, margin-positive cancers together with information on where the cancer touches the edge, in a fashion more accurate than possible from the histology slides alone.

X-ray Micro-Computed Tomography for Nondestructive Three-Dimensional (3D) X-ray Histology

Historically, micro-computed tomography (μCT) has been considered unsuitable for histologic analysis of unstained formalin-fixed, paraffin-embedded soft tissue biopsy specimens because of a lack of image contrast between the tissue and the paraffin. However, we recently demonstrated that μCT can successfully resolve microstructural detail in routinely prepared tissue specimens. Herein, we illustrate how μCT imaging of standard formalin-fixed, paraffin-embedded biopsy specimens can be seamlessly integrated into conventional histology workflows, enabling nondestructive three-dimensional (3D) X-ray histology, the use and benefits of which we showcase for the exemplar of human lung biopsy specimens. This technology advancement was achieved through manufacturing a first-of-kind μCT scanner for X-ray histology and developing optimized imaging protocols, which do not require any additional sample preparation. 3D X-ray histology allows for nondestructive 3D imaging of tissue microstructure, resolving structural connectivity and heterogeneity of complex tissue networks, such as the vascular network or the respiratory tract. We also demonstrate that 3D X-ray histology can yield consistent and reproducible image quality, enabling quantitative assessment of a tissue's 3D microstructures, which is inaccessible to conventional two-dimensional histology. Being nondestructive, the technique does not interfere with histology workflows, permitting subsequent tissue characterization by means of conventional light microscopy-based histology, immunohistochemistry, and immunofluorescence. 3D X-ray histology can be readily applied to a plethora of archival materials, yielding unprecedented opportunities in diagnosis and research of disease.

Pulmonary Acinus: Understanding the Computed Tomography Findings from an Acinar Perspective

The lung acinus is the most distal portion of the airway responsible for the gas exchange. The normal acini are not visible on conventional computed tomography (CT), but the advent of micro-CT improved the understanding of the microarchitecture of healthy acini. The comprehension of the acinar architecture is pivotal for the understanding of CT findings of diseases that involve the acini. Centriacinar emphysema, for example, presents as round areas of low attenuation due to the destruction of the most central acini with compensatory enlargement of proximal acini due to alveolar wall destruction. In pulmonary fibrosis, intralobular septal fibrosis manifests as acinar wall thickening with an overlap of acinar collapse and compensatory dilation of surrounding acini constituting the cystic disease typical of the usual interstitial pneumonia pattern. This is a state-of-the-art review to describe the acinar structure from the micro-CT perspective and display how the comprehension of the acinar structure can aid in the interpretation of its microarchitecture disruption on conventional CT.

Multimodal virtual histology of rabbit vocal folds by nonlinear microscopy and nano computed tomography

Human vocal folds (VFs) possess a unique anatomical structure and mechanical properties for human communication. However, VFs are prone to scarring as a consequence of overuse, injury, disease or surgery. Accumulation of scar tissue on VFs inhibits proper phonation and leads to partial or complete loss of voice, with significant consequences for the patient's quality of life. VF regeneration after scarring provides a significant challenge for tissue engineering therapies given the complexity of tissue microarchitecture. To establish an effective animal model for VF injury and scarring, new histological methods are required to visualize the wound repair process of the tissue in its three-dimensional native environment. In this work, we propose the use of a combination of nonlinear microscopy and nanotomography as contrast methods for virtual histology of rabbit VFs. We apply these methods to rabbit VF tissue to demonstrate their use as alternatives to conventional VF histology that may enable future clinical studies of this injury model.

A Practical Guide to Whole Slide Imaging: A White Paper From the Digital Pathology Association

Context.—

Whole slide imaging (WSI) represents a paradigm shift in pathology, serving as a necessary first step for a wide array of digital tools to enter the field. Its basic function is to digitize glass slides, but its impact on pathology workflows, reproducibility, dissemination of educational material, expansion of service to underprivileged areas, and intrainstitutional and interinstitutional collaboration exemplifies a significant innovative movement with far-reaching effects. Although the benefits of WSI to pathology practices, academic centers, and research institutions are many, the complexities of implementation remain an obstacle to widespread adoption. In the wake of the first regulatory clearance of WSI for primary diagnosis in the United States, some barriers to adoption have fallen. Nevertheless, implementation of WSI remains a difficult prospect for many institutions, especially those with stakeholders unfamiliar with the technologies necessary to implement a system or who cannot effectively communicate to executive leadership and sponsors the benefits of a technology that may lack clear and immediate reimbursement opportunity.

Objectives.—

To present an overview of WSI technology—present and future—and to demonstrate several immediate applications of WSI that support pathology practice, medical education, research, and collaboration.

Data Sources.—

Peer-reviewed literature was reviewed by pathologists, scientists, and technologists who have practical knowledge of and experience with WSI.

Conclusions.—

Implementation of WSI is a multifaceted and inherently multidisciplinary endeavor requiring contributions from pathologists, technologists, and executive leadership. Improved understanding of the current challenges to implementation, as well as the benefits and successes of the technology, can help prospective users identify the best path for success.

Recent developments in 3-D reconstruction and stereology to study the pulmonary vasculature

Alterations of the pulmonary vasculature are an important feature of human lung diseases such as chronic obstructive pulmonary disease, pulmonary hypertension, and bronchopulmonary dysplasia. Experimental studies to investigate the pathogenesis or a therapeutic intervention in animal models of these diseases often require robust, meaningful, and efficient morphometric data that allow for appropriate statistical testing. The gold standard for obtaining such data is design-based stereology. However, certain morphological characteristics of the pulmonary vasculature make the implementation of stereological methods challenging. For example, the alveolar capillary network functions according to the sheet flow principle, thus making unbiased length estimations impossible and requiring other strategies to obtain mechanistic morphometric data. Another example is the location of pathological changes along the branches of the vascular tree. For developmental defects like in bronchopulmonary dysplasia or for pulmonary hypertension, it is important to know whether certain segments of the vascular tree are preferentially altered. This cannot be overcome by traditional stereological methods but requires the combination of a three-dimensional data set and stereology. The present review aims at highlighting the great potential while discussing the major challenges (such as time consumption and data volume) of this combined approach. We hope to raise interest in the potential of this approach and thus stimulate solutions to overcome the existing challenges.

Tuboperitoneal fistula, ectopic pregnancy, and remnants of fallopian tube: a confocal microtomography analysis and 3D reconstruction of human fallopian tube pathologies

Objective: The aim of this study was to provide a three-dimensional (3D) microscopic reconstruction of morphological modifications of the fallopian tube (FT) following surgical sterilization (including tuboperitoneal fistula) and ectopic pregnancy (EP) using confocal microtomography (micro-CT). Methods: Six specimens of FT from elective and emergency surgeries were selected: three remnants of the FT (RFT) from surgical sterilization, including one presenting tuboperitoneal fistula, and three FTs with EP. The specimens were fixed in formalin and stained with Lugol solution. Micro-CT studies were conducted on the specimens using protocols adapted from biological studies. Results: Three RFTs from surgical sterilization and three FTs affected by EPs were successfully scanned using micro-CT. There was good contrast impregnation, allowing tissue segmentation and analysis of different sections of the FTs. Three FT specimens from EP exhibited considerable distortion of the tubal anatomy, mainly from the blood clot in the tubal abortion. Three RFT specimens exhibited some features observed in traditional microscopy, such as tubal distension and loss of normal anatomical characteristics of a normal FT, and indicated the presence of a tuboperitoneal fistula in one of the three specimens. Conclusion: Micro-CT can identify morphological characteristics of FT pathologies previously described in a microscopic scale, with tissue contrast and the possibility of 3D reconstruction. Micro-CT is also useful in guiding traditional sectioning of specimens for histopathological studies.

Three-dimensional virtual histology enabled through cytoplasm-specific X-ray stain for microscopic and nanoscopic computed tomography

Many histological methods require staining of the cytoplasm, which provides instrumental details for diagnosis. One major limitation is the production of 2D images obtained by destructive preparation of 3D tissue samples. X-ray absorption micro- and nanocomputed tomography (microCT and nanoCT) allows for a nondestructive investigation of a 3D tissue sample, and thus aids to determine regions of interest for further histological examinations. However, application of microCT and nanoCT to biological samples (e.g., biopsies) is limited by the missing contrast within soft tissue, which is important to visualize morphological details. We describe an eosin-based preparation overcoming the challenges of contrast enhancement and selectivity for certain tissues. The eosin-based staining protocol is suitable for whole-organ staining, which then enables high-resolution microCT imaging of whole organs and nanoCT imaging of smaller tissue pieces retrieved from the original sample. Our results demonstrate suitability of the eosin-based staining method for diagnostic screening of 3D tissue samples without impeding further diagnostics through histological methods.

Three-dimensional Imaging and Scanning: Current and Future Applications for Pathology

Imaging is vital for the assessment of physiologic and phenotypic details. In the past, biomedical imaging was heavily reliant on analog, low-throughput methods, which would produce two-dimensional images. However, newer, digital, and high-throughput three-dimensional (3D) imaging methods, which rely on computer vision and computer graphics, are transforming the way biomedical professionals practice. 3D imaging has been useful in diagnostic, prognostic, and therapeutic decision-making for the medical and biomedical professions. Herein, we summarize current imaging methods that enable optimal 3D histopathologic reconstruction: Scanning, 3D scanning, and whole slide imaging. Briefly mentioned are emerging platforms, which combine robotics, sectioning, and imaging in their pursuit to digitize and automate the entire microscopy workflow. Finally, both current and emerging 3D imaging methods are discussed in relation to current and future applications within the context of pathology.