Classical histology is the gold standard for soft-tissue analysis, and it is performed by imaging thin slices of a sample with a microscope. While the resolution is high in two dimensions, the sample preparation to be able to record images is time consuming, destructive and effectively limiting the recorded data to two dimensions. We propose virtual histology by x-ray phase-contrast computed tomography (CT) as a non-destructive imaging method to be used as a complement to classical histology. With our laboratory system, we focus on detailed imaging of soft-tissue tumours with the aim of distinguishing the tumour from healthy tissue.
Purpose: Synchrotron radiation-based tomography yields microanatomical features in human and animal tissues without physical slicing. Recent advances in instrumentation have made laboratory-based phase tomography feasible. We compared the performance of three cutting-edge laboratory systems benchmarked by synchrotron radiation-based tomography for three specimens. As an additional criterion, the user-friendliness of the three microtomography systems was considered.
Approach: The three tomography systems—SkyScan 2214 (Bruker-microCT, Kontich, Belgium), Exciscope prototype (Stockholm, Sweden), and Xradia 620 Versa (Zeiss, Oberkochen, Germany)—were given 36 h to measure three medically relevant specimens, namely, zebrafish larva, archaeological human tooth, and porcine nerve. The obtained datasets were registered to the benchmark synchrotron radiation-based tomography from the same specimens and selected ones to the SkyScan 1275 and phoenix nanotom m® laboratory systems to characterize development over the last decade.
Results: Next-generation laboratory-based microtomography almost reached the quality achieved by synchrotron-radiation facilities with respect to spatial and density resolution, as indicated by the visualization of the medically relevant microanatomical features. The SkyScan 2214 system and the Exciscope prototype demonstrated the complementarity of phase information by imaging the eyes of the zebrafish larva. The 3-μm thin annual layers in the tooth cementum were identified using Xradia 620 Versa.
Conclusions: SkyScan 2214 was the simplest system and was well-suited to visualizing the wealth of anatomical features in the zebrafish larva. Data from the Exciscope prototype with the high photon flux from the liquid metal source showed the spiral nature of the myelin sheaths in the porcine nerve. Xradia 620 Versa, with detector optics as typically installed for synchrotron tomography beamlines, enabled the three-dimensional visualization of the zebrafish larva with comparable quality to the synchrotron data and the annual layers in the tooth cementum.
Purpose: Surgery is an essential part of the curative plan for most patients affected with solid tumors. The outcome of such surgery, e.g., recurrence rates and ultimately patient survival, depends on several factors where the resection margin is of key importance. Presently, the resection margin is assessed by classical histology, which is time-consuming (several days), destructive, and basically only gives two-dimensional information. Clearly, it would be advantageous if immediate feedback on tumor extension in all three dimensions were available to the surgeon intraoperatively.
Approach: We investigate a laboratory propagation-based phase-contrast x-ray computed tomography system that provides the resolution, the contrast, and, potentially, the speed for this purpose. The system relies on a liquid-metal jet microfocus source and a scintillator-coated CMOS detector. Our study is performed on paraffin-embedded non-stained samples of human pancreatic neuroendocrine tumors, liver intrahepatic cholangiocarcinoma, and pancreatic serous cystic neoplasm (benign).
Results: We observe tumors with distinct and sharp edges having cellular resolution (∼10 μm) as well as many assisting histological landmarks, allowing for resection margin assessment. All x-ray data are compared with classical histology. The agreement is excellent.
Conclusion: We conclude that the method has potential for intraoperative three-dimensional virtual histology.
Inline phase tomography using synchrotron radiation with sub-micrometer voxel sizes is nowadays the gold standard for investigation of soft and hard tissues with micron resolution. Recent developments on detectors and X-ray sources allow the transfer of the technique into laboratory environment. For the comparison of three manufacturers, we performed microtomography with advanced laboratory microtomography devices with micron resolution on a porcine nerve, a zebrafish embryo and a historic human tooth. These data sets were also compared with data acquired at the ANATOMIX beamline at Synchrotron Soleil and the TOMCAT beamline at SLS. For the lab-based experiments following scanners were chosen: Skyscan 2214 (Bruker-microCT, Kontich, Belgium), Xradia 620 Versa (Zeiss, Oberkochen, Germany) and a prototype with a MetalJet X-ray source from Exillum from the company Exciscope (Stockholm, Sweden). All devices contained detectors including X-ray optics.
Surgery is an essential part of the curative plan for most patients affected with solid tumors. The outcome of such surgery, e.g., recurrence rates and ultimately patient survival, depends on several factors where the resection margin is of key importance. Presently the resection margin is assessed by classical histology, which is time-consuming (several days), destructive, and basically only gives two-dimensional information. Clearly it would be advantageous if immediate feedback on tumor extension in all three dimensions were available to the surgeon intra-operatively. In the present paper we investigate a laboratory propagation-based phase-contrast xray computed tomography (CT) system that provides the resolution, contrast, and, potentially, the speed for this purpose. The system relies on a liquid-metal jet micro-focus source and a scintillator-coated CMOS detector. The study is performed on paraffin-embedded non-stained samples of human pancreatic neuroendocrine tumors, liver intrahepatic cholangiocarcinoma, and pancreatic serous cystic neoplasm (benign). We observe tumors with distinct and sharp edges having cellular resolution (∼10 μm) as well as many assisting histological landmarks, allowing for resection margin assessment. All x-ray data is compared with classical histology. The agreement is excellent, and we conclude that the method has potential for intra-operative three-dimensional virtual histology.
Ancient remains from humans, animals and plants hold valuable information about our history. X-ray imaging methods are often, because of their non-destructive nature, used in the analysis of such samples. The classical x-ray imaging methods, radiography and computed tomography (CT), are based on absorption, which works well for radiodense structures like bone, but gives limited contrast for textiles and soft tissues, which exhibit high x-ray transmission. Destructive methods, such as classical histology, have historically been used for analysing ancient soft tissue but the extent to which it is used today is limited because of the fragility and value of many ancient samples. For detailed, non-destructive analysis of ancient biological samples, we instead propose x-ray phase-contrast CT, which like conventional CT gives volume data but with the possibility of better resolution through the detection of phase shift. Using laboratory x-ray sources, we here demonstrate the capabilities of phase-contrast tomography of dried biological samples. Virtual histological analysis of a mummified human hand from ancient Egypt is performed, revealing remains of adipose cells in situ, which would not be possible with classical histology. For higher resolution, a lab-based nano-CT arrangement based on a nanofocus transmission x-ray source is presented. With an x-ray emission spot of 300 nm the system shows potential for sub-micronresolution 3D imaging. For characterisation of the performance of phase-contrast imaging of dried samples a piece of wood is imaged. Finally, we present the first phase-contrast CT data from our nano-CT system, acquired of the dried head of a bee.
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