D. Van Loo

An exploratory study of contrast agents for soft tissue visualization by means of high resolution X-ray computed tomography imaging.

High resolution X‐ray computed tomography (CT), or microCT, is a promising and already widely used technique in various scientific fields. Also for histological purposes it has great potential. Although microCT has proven to be a valuable technique for the imaging of bone structures, the visualization of soft tissue structures is still an important challenge due to their low inherent X‐ray contrast. One way to achieve contrast enhancement is to make use of contrast agents. However, contrary to light and electron microscopy, knowledge about contrast agents and staining procedures is limited for X‐ray CT. The purpose of this paper is to identify useful X‐ray contrast agents for soft tissue visualization, which can be applied in a simple way and are also suited for samples larger than (1 cm)3. And 28 chemical substances have been investigated. All chemicals were applied in the form of concentrated aqueous solutions in which the samples were immersed. First, strips of green Bacon were stained to evaluate contrast enhancement between muscle and adipose tissue. Furthermore it was also tested whether the contrast agents remained fixed in the tissue after staining by re‐immersing them in water. Based on the results, 12 contrast agents were selected for further testing on postmortem mice hind legs, containing a variety of different tissues, including muscle, fat, bone, cartilage and tendons. It was evaluated whether the contrast agents allowed a clearer distinction between the different soft tissue structures present. Finally also penetration depth was measured. And 26 chemicals resulted in contrast enhancement between muscle and adipose tissue in the Bacon strips. Mercury(II)chloride (HgCl2), phosphotungstic acid (PTA), phosphomolybdic acid (PMA) and ammonium orthomolybdate ((NH4)2MoO4) remained fixed after re‐immersion in water. The penetration tests showed that potassium iodide (KI) and sodium tungstate can be most efficiently used for large samples of the order of several tens of cm3. PMA, PTA, HgCl2 and also to a lesser extent Na2WO4 and (NH4)2MoO4 allowed a clearer distinction between the different soft tissue structures present.

A LabVIEW® based generic CT scanner control software platform.

UGCT, the Centre for X-ray tomography at Ghent University (Belgium) does research on X-ray tomography and its applications. This includes the development and construction of state-of-the-art CT scanners for scientific research. Because these scanners are built for very different purposes they differ considerably in their physical implementations. However, they all share common principle functionality. In this context a generic software platform was developed using LabVIEW® in order to provide the same interface and functionality on all scanners. This article describes the concept and features of this software, and its potential for tomography in a research setting. The core concept is to rigorously separate the abstract operation of a CT scanner from its actual physical configuration. This separation is achieved by implementing a sender-listener architecture. The advantages are that the resulting software platform is generic, scalable, highly efficient, easy to develop and to extend, and that it can be deployed on future scanners with minimal effort.

Modeling the Impact of Partial Hepatectomy on the Hepatic Hemodynamics Using a Rat Model

Due to the growing shortage of donor livers, more patients are waiting for transplantation. Living donor liver transplantation may help expanding the donor pool, but is often confronted with the small-for-size syndrome. Since the hemodynamic effects of partial hepatectomy are not fully understood, we developed an electrical rat liver model to compare normal with resected liver hemodynamics. Detailed geometrical data and 3-D reconstructions of the liver vasculature of two rats were gathered by combining vascular corrosion casting, micro-CT scanning, and image processing. Data extrapolations allowed obtaining a total liver pressure- and flow-driven electrical analog. Subsequently, virtual resections led to 70%, 80%, or 90% partial hepatectomy models. Results demonstrated hyperperfusion effects such as portal hypertension and elevated lobe-specific portal venous flows (11, 12, and 24 mmHg, and 1.0-3.0, 1.8-3.5, and 7.4 ml/min for 70%, 80%, and 90% hepatectomy, respectively). Comparison of two 90% resection techniques demonstrated different total arterial flows (0.28 ml/min versus 0.61 ml/min), portal (24 mmHg versus 21 mmHg), and sinusoidal pressures (14 mmHg versus 9.5-12 mmHg), probably leading to better survival for lower portal and sinusoidal pressures. Toward the future, the models may be extrapolated to human livers and help us to optimize hepatectomy planning.

Potential of X-ray computed tomography for 3D anatomical analysis and microdensitometrical assessment in wood research with focus on wood modification

Abstract Studying structure and chemistry of wood and wood-based materials is the backbone of all wood research and many techniques are at hand to do so. A very valuable modality is X-ray computed tomography (CT), able to non-destructively probe the three-dimensional (3D) structure and composition. In this paper, we elaborate on the use of Nanowood, a flexible multi-resolution X-ray CT set-up developed at UGCT, the Ghent University Centre for X-ray Tomography. The technique has been used successfully in many different fields of wood science. It is illustrated how 3D structural and microdensitometrical data can be obtained using different scan set-ups and protocols. Its potential for the analysis of modified wood is exemplified, e.g. for the assessment of wood treated with hydrophobing agents, localisation of modification agents, pathway analysis related to functional tissues, dimensional changes due to thermal treatment, etc. Furthermore, monitoring of transient processes is a promising field of activity too.

Anatomical description and morphometry of the skeleton of the common marmoset (Callithrix jacchus)

Callithrix jacchus (common marmoset) is regularly used in biomedical research, including for studies involving the skeleton. To support these studies, skeletons of healthy animals that had been euthanized for reasons not interfering with skeletal anatomy were prepared. The marmoset dental formula 2I-1C-3P-2M of each oral quadrant is atypical for New World monkeys which commonly possess a third molar. Seven cervical, 12–13 thoracic, 7–6 lumbar, 2–3 sacral and 26–29 caudal vertebrae are present, the thoracolumbar region always comprising 19 vertebrae. A sigmoid clavicle connects the scapula with the manubrium of the sternum. Depending on the number of thoracic vertebrae, 4–5 sternebrae are located between the manubrium and xiphoid process. Wide interosseous spaces separate the radius from the ulna, and the tibia from the fibula. A small sesamoid bone is inserted in the m. abductor digiti primi longus at the medial border of the carpus, a pair of ovoid sesamoid bones is located at the palmar/plantar sides of the trochleae of each metapodial bone, and round fabellae articulate with the proximal surfaces of the femoral condyles. Male marmosets possess a small penile bone. Both the front and hind feet have five digits. The hallux possesses a flat nail, whereas all other digits present curved claws. Interestingly, a central bone is present in both the carpus and tarsus. This study provides a description and detailed illustrations of the skeleton of the common marmoset as an anatomical guide for further biomedical research.

From Human Liver Vascular Corrosion Cast to Electrical Analog Model of the Hepatic Blood Flow

Machine perfusion (MP) is experiencing a revival in organ preservation due to the limitations of static cold storage and the need for better preservation methods for expanded criteria donors. Liver MP prototypes, however, face problems such as potential damage to sinusoidal endothelial cells, and heterogeneous perfusion related to the complex hepatic microcirculation.Copyright