N. de Clerck

Quantitative analysis of bone mineral content by x-ray microtomography

A new non-destructive method based on x-ray microtomography (micro-CT) was developed to measure calcium density in bone. X-ray micro-CT was used as a quantitative approach to acquire and reconstruct virtual cross-sections through the sample. Accurate beam-hardening correction was implemented. Grey values in the virtual cross-sections were calibrated as calcium mineral density in bone. From these cross-sections, three-dimensional models were created. Calcium content was calculated directly from images and expressed as percentage per volume and per weight. Calcium mineral density was studied by this method in a unique set of bones isolated from newts (Pleurodeles waltlii Michah) that had travelled into space. A demineralization of 10% was shown as a consequence of sustained micro-gravity.

High resolution micro-CT scanning as an innovatory tool for evaluation of the surgical positioning of cochlear implant electrodes

X-ray microtomography (micro-CT) is a new technique allowing for visualization of the internal structure of opaque specimens with a quasi-histological quality. Among multiple potential applications, the use of this technique in otology is very promising. Micro-CT appears to be ideally suited for in vitro visualization of the inner ear tissues as well as for evaluation of the electrode damage and/or surgical insertion trauma during implantation of the cochlear implant electrodes. This technique can greatly aid in design and development of new cochlear implant electrodes and is applicable for temporal bone studies. The main advantage of micro-CT is the practically artefact-free preparation of the samples and the possibility of evaluation of the interesting parameters along the whole insertion depth of the electrode. This paper presents the results of the first application of micro-CT for visualization of the inner ear structures in human temporal bones and for evaluation of the surgical positioning of the cochlear implant electrodes relative to the intracochlear soft tissues.

In vivo assessment of emphysema in mice by high resolution X-ray microtomography

High resolution X‐ray microtomography (micro‐CT) was used for the detection of emphysema in live mice. Emphysema was induced in C57BL/6 J mice by intratracheal instillation of different amounts of porcine pancreatic elastase. This emphysema could be clearly detected by micro‐CT seven weeks post‐treatment: analysis of the whole data set of virtual cross‐sections showed the presence of a dose‐dependent level of emphysema.

3D in-vivo X-ray microtomography of living snails

In this paper we report the first in‐vivo scanning of living snails by desktop X‐ray microtomograph with a resolution up to 10 m. Consecutive cross‐sections were acquired without destroying the specimen. Subsequently, 3D images were reconstructed. The results clearly demonstrate the possibilities of in‐vivo scanning. Processes of growth and regeneration of living snails were visualized over a period of time.

Uniform sarcomere behaviour during twitch of intact single cardiac cells

Behaviour of sarcomere length was analysed in different regions of single cardiac cells (n = 249) of the ventricle, both at rest (n = 144) and during twitch contractions (n = 57). At rest, regional distribution of sarcomere length proved to be uniform. In the leaky cell (n = 48), resting sarcomere length was not affected over longer periods of time (up to 2 h), nor by lowering the ATP concentration (from 5 mM to 2.5 mM and 500 microM), nor by increasing free calcium within subactivating ranges (5, 20, 60 microM). No statistical differences could be detected between resting cell dimensions and sarcomere length between cells isolated from left and right ventricle (n = 64), nor between cells from epicardial or endocardial layers (n = 80). During twitch contraction in the intact unloaded cardiac cell (n = 32), sarcomere lengths in different regions were analysed every 20 ms and behaved synchronously, presenting arguments for uniformity during the myocardial contraction-relaxation cycle in the free-lying intact cardiac cell.

Possibilities and limits of X-ray microtomography for in vivo and ex vivo detection of vascular calcifications

In the present paper, vascular calcifications due to chronic renal failure in rats are studied by X-ray microtomography (μ-CT). Although μ-CT is traditionally used as an imaging technique, a quantitative analysis of data obtained by in vivo and ex vivo μ-CT is described and discussed. By comparison with traditional destructive methods, such as histomorphometry and atomic absorption, the detection limits for calcium were determined in living rats and in extracted aortas. μ-CT proved to be an effective non-invasive imaging technique allowing non-destructive quantification of ectopic calcifications.