Name: image rendering techniques in postmortem computed tomography: evaluation of biological health and profile in stranded cetaceans
Uploaded: 2020-09-27T15:00:00
Description: Watch this Scientific Journal Video about Image Rendering Techniques in Postmortem Computed Tomography: Evaluation of Biological Health and Profile in Stranded Cetaceans at JoVE.com

The authors would like to thank the Agriculture, Fisheries and Conservation Department of the Hong Kong Special Administrative Region Government for the continuous support in this project. Sincere appreciation is also extended to veterinarians, staff, and volunteers from the Aquatic Animal Virtopsy Lab, City University of Hong Kong, Ocean Park Conservation Foundation Hong Kong and Ocean Park Hong Kong&#160;for paying great effort on the stranding response in this project. Special gratitude is owed to technicians in CityU Veterinary Medical Centre and Hong Kong Veterinary Imaging Centre for operating the CT and MRI units for the present study. Any opinions, findings, conclusions or recommendations expressed herein do not necessarily reflect the views of the Marine Ecology Enhancement Fund or the Trustee. This project was funded by the Hong Kong Research Grants Council (Grant number: UGC/FDS17/M07/14), and the Marine Ecology Enhancement Fund (grant number: MEEF2017014, MEEF2017014A,&#160;MEEF2019010 and MEEF2019010A), Marine Ecology Enhancement Fund, Marine Ecology &#38; Fisheries Enhancement Funds Trustee Limited. Special thanks to Dr. Mar&#237;a Jos&#233; Robles Malagamba for English editing of this manuscript.

NOTE: In the framework of the Hong Kong cetacean virtopsy stranding response program, stranded cetaceans were routinely examined by PMCT. The authors were in charge of virtopsy scanning, data postprocessing (e.g., image reconstruction and rendering), data interpretation, and virtopsy reporting1. This advanced technology emphasizes attentive findings and gives insights on the initial investigation of PM findings prior to conventional necropsy (https://www.facebook.com/aquanimallab).
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For the clear visualization of virtopsy datasets, 8 image rendering techniques, consisting of both 2D and 3D rendering, were routinely applied to each stranded carcass for the PM investigation of their biological health and profile. These rendering techniques included MPR, CPR, MIP, MinIP, DVR, segmentation, TF, and PVR. Diverse rendering techniques are complementarily used together with windowing adjustment. The concepts of each image reformation technique and advantages are also described.
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Virtopsy, also known as postmortem (PM) imaging, is the examination of a carcass with advanced cross-sectional imaging modalities, including postmortem computed tomography (PMCT), postmortem magnetic resonance imaging (PMMRI), and ultrasonography1. In humans, PMCT is useful in investigating traumatic cases of skeletal alterations2,3, foreign bodies, gaseous findings4,5,6, and pathologies of the vascular system7,8,9. Since 2014, virtopsy has been routinely implemented in the Hong Kong cetacean stranding response program1. PMCT and PMMRI are able to depict patho-morphological findings on carcasses that are too decomposed to be evaluated by conventional necropsy. The non-invasive radiological assessment is objective and digitally storable, allowing second opinion or retrospective studies years later1,10,11. Virtopsy has become a valuable alternative technique to provide new insights of PM findings in stranded marine animals12,13,14,15,16. Combined with necropsy, which is the gold standard to explain the pathophysiological reconstruction and cause of death17, the biological health and profile of the animals can be addressed. Virtopsy has been gradually recognized and implemented into stranding response programs worldwide, including but not limited to Costa Rica, Japan, Mainland China, New Zealand, Taiwan, Thailand and USA1.
Image rendering techniques in radiology use computer algorithms to transform numbers into information about the tissue. For example, radiological density is expressed in conventional X-rays and CT. The vast quantity of volumetric data is stored in the Digital Imaging and Communications in Medicine (DICOM) format. CT images can be used to produce isotropic voxel data using two-dimensional (2D) and three-dimensional (3D) image rendering in a postprocessing 3D workstation for high resolution visualization18,19. Quantitative data and results are mapped to transform serially acquired axial images into 3D images with gray-scale or color parameters19,20,21. Choosing an appropriate data visualization method from diverse rendering techniques is an essential technical determinant of the visualization quality, which significantly affects the analysis and interpretation of radiological findings21. This is particularly critical for stranding work that involves personnel without any radiology background, who need to understand the results in different circumstances17. The goal of implementing these image rendering techniques is to enhance the quality on the visualization of anatomical details, relationships and clinical findings, which boosts the diagnostic value of imaging and allows an effective rendition of the defined regions of interest17,19,22,23,24,25.
Although the primary axial CT/MRI images contain most information, they may limit accurate diagnosis or documentation of pathologies as structures cannot be viewed in various orthogonal planes. Image reformation at other anatomically aligned planes permits visualization of structural relationships from another perspective without having to reposition the body26. As medical anatomy and forensic pathology data are predominantly 3D in nature, color-coded PMCT images and 3D reconstructed images are preferred to gray-scale images and 2D slice images in view of improved understandability and suitability for courtroom adjudications27,28. With the advances in PMCT technology, a concern of visualization exploration (i.e., the creation and interpretation of 2D and 3D image) in cetacean PM investigation has been raised12,29. Various volumetric rendering techniques in the radiology workstation allow radiologists, technicians, referring clinicians (e.g., veterinarians and marine mammal scientists), and even laymen (e.g., stranding response personnel, government officers and general public) to visualize and study the regions of interest. Yet, the choice of a suitable technique and confusion of terminology remain a major issue. It is necessary to understand the basic concept, strengths and limitations of the common techniques, since it would significantly influence the diagnostic value and interpretation of radiological findings. Misuse of techniques may generate misleading images (e.g., images that have distortions, rendering errors, reconstruction noises or artefacts) and lead to an incorrect diagnosis30.
The present study aims to assess 8 essential image rendering techniques in PMCT that were used to identify most of the PM findings in stranded cetaceans in Hong Kong waters. Descriptions and practical examples of each technique are provided to guide radiologists, clinicians, and veterinarians worldwide through the often difficult and complicated realm of PMCT image rendering and review for the evaluation of biological health and profile.

<table>
	<tbody>
		<tr>
			<td>Aquarius iNtuition workstation</td>
			<td>TeraRecon Inc</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Siemens 64-row multi-slice spiral CT scanner Somatom go.Up</td>
			<td>Siemens Healthineers</td>
			<td>NA</td>
			<td></td>
		</tr>
	</tbody>
</table>

image rendering techniques in postmortem computed tomography: evaluation of biological health and profile in stranded cetaceans

With 6 years of experience in implementing virtopsy routinely into the Hong Kong cetacean stranding response program, standardized virtopsy procedures, postmortem computed tomography (PMCT) acquisition, postprocessing, and evaluation were successfully established. In this pioneer cetacean virtopsy stranding response program, PMCT was performed on 193 stranded cetaceans, providing postmortem findings to aid necropsy and shed light on the biological health and profile of the animals. This study aimed to assess 8 image rendering techniques in PMCT, including multiplanar reconstruction, curved planar reformation, maximum intensity projection, minimum intensity projection, direct volume rendering, segmentation, transfer function, and perspective volume rendering. Illustrated with practical examples, these techniques were able to identify most of the PM findings in stranded cetaceans and served as a tool to investigate their biological health and profile. This study could guide radiologists, clinicians and veterinarians through the often difficult and complicated realm of PMCT image rendering and reviewing.

From January 2014 to May 2020, a total of 193 cetaceans that stranded in Hong Kong waters were examined by PMCT, including 42 Indo-Pacific humpback dolphins (Sousa chinensis), 130 Indo-Pacific finless porpoises (Neophocaena phocaenoides) and 21 other species. A whole-body scan was performed on 136 carcasses while 57 were partial scans on skulls and flippers. Anatomical features and pathologies commonly observed were illustrated with the 8 image rendering techniques for the evaluation of the stranded cet...

Watch this Scientific Journal Video about Image Rendering Techniques in Postmortem Computed Tomography: Evaluation of Biological Health and Profile in Stranded Cetaceans at JoVE.com

Image Rendering Techniques in Postmortem Computed Tomography: Evaluation of Biological Health and Profile in Stranded Cetaceans

The Hong Kong cetacean stranding response program has incorporated postmortem computed tomography, which provides valuable information on the biological health and profile of the deceased animals. This study describes 8 image rendering techniques that are essential for the identification and visualization of postmortem findings in stranded cetaceans, which will help clinicians, veterinarians and stranding response personnel worldwide to fully utilize the radiological modality.

With 6 years of experience in implementing virtopsy routinely into the Hong Kong cetacean stranding response program, standardized virtopsy procedures, ...

Research

JoVE Journal

Biology

Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System

A magnetic modulation biosensing system (MMB) [1,2] rapidly and homogeneously detected biological targets at low concentrations without any washing or ...

Evaluation of the Spatial Distribution of &gamma;H2AX following Ionizing Radiation

Evaluation of the Spatial Distribution of ÃƒÅ½Ã‚Â³H2AX following Ionizing Radiation

An early molecular response to DNA double-strand breaks (DSBs) is phosphorylation of the Ser-139 residue within the terminal SQEY motif of the histone ...

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may ...

Time-lapse Microscopy of Early Embryogenesis in Caenorhabditis elegans

Time-lapse Microscopy of Early Embryogenesis in Caenorhabditis elegans

Caenorhabditis elegans has often been used as a model system in studies of early developmental processes.  The transparency of the 
embryos, the genetic ...

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the ...

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway ...

High-resolution Time-lapse Imaging and Automated Analysis of Microtubule Dynamics in Living Human Umbilical Vein Endothelial Cells

The physiological process by which new vasculature forms from existing vasculature requires specific signaling events that trigger morphological changes ...

Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction ...

The Assembly and Application of 'Shear Rings': A Novel Endothelial Model for Orbital, Unidirectional and Periodic Fluid Flow and Shear Stress

Deviations from normal levels and patterns of vascular fluid shear play important roles in vascular physiology and pathophysiology by inducing adaptive as ...

Micron-scale Phenotyping Techniques of Maize Vascular Bundles Based on X-ray Microcomputed Tomography

It is necessary to accurately quantify the anatomical structures of maize materials based on high-throughput image analysis techniques. Here, we provide a ...