Innovations in laboratory-based dynamic micro-CT to accelerate in situ research.

In the past few years, dynamic computed tomography (CT) approaches or uninterrupted acquisitions of deforming materials have rapidly emerged as an essential technique to understand material evolution, facilitating in situ investigations ranging from mechanical deformation to fluid flow in porous materials and beyond. Developments at synchrotron facilities have led this effort, pointing to the future of the technique. In the laboratory, recent developments at TESCAN XRE have made it possible to image, reconstruct and inspect dynamic processes in the laboratory with a temporal resolution below 10 s, meaning that an entire acquisition from 0 to 360° is completed within 10 s. The aim of this study is to explore the challenges and innovations that have led to the ability to perform high speed, dynamic acquisitions. A unique horizontally rotating gantry based micro-CT system was developed to facilitate complex in situ experiments. In doing so, the sample stays fixed while source and detector are uninterruptedly rotating around a vertical axis. In this work, the dynamic CT method with this rotating gantry based system will be described by two application examples: (1) deformation and collapse of a delicate beer foam and (2) in situ baking process of pastry. For the pastry baking process, an oven was needed to reach baking temperature. In a conventional micro-CT system, where the sample rotates, it is not so obvious to rotate an oven with sensor and heating cables. On the other hand, the delicate foam of a collapsing beer head is able to rotate, but because of the tangential convection during fast rotation (<10 s), it could influence the bubble detachment and liquid drainage and thus also the foam degradation. To investigate both processes, a horizontally rotating gantry based micro-CT is required. For both examples it was possible to quantify the key parameters such as pore size and distribution to better understand the rise and fall of porous foams. These examples will highlight the recent progress in adapting micro-CT workflows to accommodate uninterrupted imaging of dynamic events and point to opportunities for future continued development. LAY DESCRIPTION: Micro-CT allows the nondestructive visualisation of internal structures and is being used routinely in the field of Material Science, Geoscience, Life Science and more. Because of its nondestructive aspect, micro-CT is optimal to take repetitive scans of the same sample over time. The combination of taking different scans over time is so called time-resolved CT. By doing so, crucial insights can be obtained on how materials form, deform and perform over time or under certain external conditions. TESCAN XRE have made it possible to image, reconstruct and inspect dynamic processes in the laboratory with a temporal resolution below 10 s. The dynamic CT method will be described through the lens of two application examples: (1) deformation and collapse of a delicate beer foam and (2) in situ baking process of pastry. These examples will highlight the recent progress in adapting micro-CT workflows to accommodate imaging of dynamic events and point to opportunities for future continued development.

A new algorithm for the discrimination of actinic keratosis from normal skin and squamous cell carcinoma based on in vivo analysis of optical properties by high-definition optical coherence tomography.

BACKGROUND: High-definition optical coherence tomography (HD-OCT) features of actinic keratosis (AK) may aid in its diagnosis and therapeutic strategy. A diagnostic algorithm permitting discrimination of AK from squamous cell carcinoma (SCC) and normal skin has been proposed. However, diagnostic accuracy strongly depends on the experience of physicians. In two recent studies, it was demonstrated that HD-OCT permits to quantify in vivo optical properties such as light attenuation in intrinsic ageing skin, in melanocytic lesions and in basal cell carcinoma. This approach seems to permit a semiautomated classification of lesions easier to handle by non-experts. OBJECTIVES: The aim of this paper was to quantify in vivo optical properties of facial located AK/SCC lesions, such as light attenuation, by HD-OCT. Additional objectives were to determine the best critical value of these optical properties for discrimination of AK from SCC and from normal sun exposed skin and to subdifferentiate AKs. METHODS: The technique of semi-log plot has been implemented on HD-OCT signals. This permitted the in vivo measurement of OCT signals coming from the skin entrance up to the superficial reticular dermis. Moreover, relative attenuation factor (µraf ) at different skin layers (1-3) could be determined. RESULTS: Optical properties with high diagnostic accuracy (DA) and high negative predictive values (NPV) could be defined permitting the differentiation between normal skin, non-Bowenoid AK without follicular involvement, non-Bowenoid AK with follicular involvement, Bowenoid AK, hypertrophic and lichenoid form of AK and squamous cell carcinoma. CONCLUSION: HD-OCT seems to enable the combination of in vivo morphological analysis of cellular and 3D microarchitectural structures with in vivo analysis of optical properties of tissue scatterers in AK/SCC lesions and normal sun-exposed skin. In vivoHD-OCT analysis of optical properties permits AK discrimination from SCC and AK subdifferentiation with higher accuracy than in vivoHD-OCT analysis of morphology alone.

In vivo assessment of optical properties of melanocytic skin lesions and differentiation of melanoma from non-malignant lesions by high-definition optical coherence tomography.

One of the most challenging problems in clinical dermatology is the early detection of melanoma. Reflectance confocal microscopy (RCM) is an added tool to dermoscopy improving considerably diagnostic accuracy. However, diagnosis strongly depends on the experience of physicians. High-definition optical coherence tomography (HD-OCT) appears to offer additional structural and cellular information on melanocytic lesions complementary to that of RCM. However, the diagnostic potential of HD-OCT seems to be not high enough for ruling out the diagnosis of melanoma if based on morphology analysis. The aim of this paper is first to quantify in vivo optical properties such as light attenuation in melanocytic lesions by HD-OCT. The second objective is to determine the best critical value of these optical properties for melanoma diagnosis. The technique of semi-log plot whereby an exponential function becomes a straight line has been implemented on HD-OCT signals coming from four successive skin layers (epidermis, upper papillary dermis, deeper papillary dermis and superficial reticular dermis). This permitted the HD-OCT in vivo measurement of skin entrance signal (SES), relative attenuation factor normalized for the skin entrance signal (µ raf1) and half value layer (z 1/2). The diagnostic accuracy of HD-OCT for melanoma detection based on the optical properties, µ raf1 , SES and z 1/2 was high (95.6, 82.2 and 88.9 %, respectively). High negative predictive values could be found for these optical properties (96.7, 89.3 and 96.3 %, respectively) compared to morphologic assessment alone (89.9 %), reducing the risk of mistreating a malignant lesion to a more acceptable level (3.3 % instead of 11.1 %). HD-OCT seems to enable the combination of in vivo morphological analysis of cellular and 3-D micro-architectural structures with in vivo analysis of optical properties of tissue scatterers in melanocytic lesions. In vivo HD-OCT analysis of optical properties permits melanoma diagnosis with higher accuracy than in vivo HD-OCT analysis of morphology alone.

High-definition optical coherence tomography intrinsic skin ageing assessment in women: a pilot study.

Several non-invasive two-dimensional techniques with different lateral resolution and measurable depth range have proved to be useful in assessing and quantifying morphological changes in skin ageing. Among these, only in vivo microscopy techniques permit histometric measurements in vivo. Qualitative and quantitative assessment of chronological (intrinsic) age-related (IAR) morphological changes of epidermis, dermo-epidermal junction (DEJ), papillary dermis (PD), papillary-reticular dermis junction and reticular dermis (RD) have been performed by high-definition optical coherence tomography in real time 3-D. HD-OCT images were taken at the internal site of the right upper arm. Qualitative HD-OCT IAR descriptors were reported at skin surface, at epidermal layer, DEJ, PD and upper RD. Quantitative evaluation of age-related compaction and backscattered intensity or brightness of different skin layers was performed by using the plugin plot z-axis profile of ImageJ(®) software permitting intensity assessment of HD-OCT (DICOM) images (3-D images). Analysis was in blind from all clinical information. Sixty, fair-skinned (Fitzpatrick types I-III) healthy females were analysed retrospectively in this study. The subjects belonged to three age groups: twenty in group I aged 20-39, twenty in group II aged 40-59 and twenty in group III aged 60-79. Only intrinsic ageing in women has been studied. Significant age-related qualitative and quantitative differences could be noticed. IAR changes in dermal matrix fibers morphology/organisation and in microvasculature were observed. The brightness and compaction of the different skin layers increased significantly with intrinsic skin ageing. The depth of visibility of fibers in RD increased significantly in the older age group. In conclusion, HD-OCT allows 3-D in vivo and real time qualitative and quantitative assessment of chronological (intrinsic) age-related morphological skin changes at high resolution from skin surface to a depth of the superficial reticular dermis.

High-definition optical coherence tomography algorithm for the discrimination of actinic keratosis from normal skin and from squamous cell carcinoma.

BACKGROUND: Preliminary studies described morphological features of actinic keratosis (AK) and squamous cell carcinoma (SCC) imaged by High-Definition Optical Coherence Tomography (HD-OCT) and suggested that this technique may aid in their diagnosis. However, systematic studies evaluating the accuracy of HD-OCT for the diagnosis of AK and SCC are lacking so far. OBJECTIVE: In this study, we sought to design an algorithm for AK classification that could (i) distinguish SCC from AK and normal skin, (ii) differentiate AK from normal skin and (iii) discriminate AKs with adnexal involvement from those without. METHODS: A total of 53 histopathologically confirmed lesions (37 AKs and 16 SCC) were imaged by HD-OCT. Fifty-three HD-OCT images of normal skin of healthy volunteers, with matched age, skin type and anatomic site, were taken as reference. By comparing these 106 en face and cross-sectional HD-OCT images, particular features were selected based on their potential to discriminate AK from normal skin and from SCC, and to assess adnexal involvement in AK. This study represents a training set not a testing set. Severe (>300 µm) hyperkeratotic AKs were not included in this study. RESULTS: Particular features with high Phi coefficient could be identified. The absence of an outlined dermo-epidermal junction (DEJ) on cross-sectional images allowed discriminating SCC from AK and normal skin (Phi coefficient = 0.84). AK could be discriminated from normal skin in both imaging modes by the presence of alternating hyperkeratosis/parakeratosis in cross-sectional mode and/or variability in shape, size and reflectivity of cells (atypical honeycomb pattern) in en face mode. Adnexal involvement of AK could be assessed by the disappearance of the typical cocarde image of adnexal epithelium in en face mode. CONCLUSION: This study provides select 3-D HD-OCT features having a potential to discriminate SCC from AK and normal skin. Based on these particular features with high Phi coefficient, a diagnostic algorithm is designed which will be used later in validation studies to determine HD-OCT accuracy in AK/SCC classification.

High-definition optical coherence tomography algorithm for discrimination of basal cell carcinoma from clinical BCC imitators and differentiation between common subtypes.

BACKGROUND: Preliminary studies have described morphological features of basal cell carcinoma (BCC) imaged by high-definition optical coherence tomography (HD-OCT) and suggested that this technique may aid in its diagnosis and management. However, systematic studies evaluating the accuracy of HD-OCT for the diagnosis of BCC are lacking. OBJECTIVE: The aim of this study was to identify three-dimensional (3-D) HD-OCT features able i) to distinguish BCC from clinical BCC imitators and ii) to discriminate between the most common BCC subtypes. Based on these particular features, a diagnostic algorithm will be suggested. METHOD: A total of 50 histopathologically confirmed BCCs (18 superficial, 19 nodular, 13 infiltrative) were imaged by HD-OCT at the centre of the lesion prior to standard surgical excision and subsequent histopathological analysis. Fifty images of clinical BCC imitators were also retrieved as a 'pitfalls' group. RESULTS: The simultaneous presence of grey/dark subepidermal (hemi-spherical) or intradermal lobulated structure(s) presenting a typical cockade feature in both HD-OCT modes was a significant feature for BCC diagnosis. Features discriminating between BCC subtypes were location of the roof of BCC lobules, vascular pattern of the papillary plexus and stretching effect on the stroma. Clinical BCC imitators such as actinic keratosis, compound and intradermal naevi, amelanotic melanoma, sebaceous hyperplasia and small haemangioma could be differentiated from BCC by means of HD-OCT. CONCLUSION: This study provides a thorough description of 3-D HD-OCT features that can permit discrimination of BCC from clinical BCC imitators and differentiation of BCC subtypes. Based on these features, a diagnostic algorithm is proposed which requires additional validation, but enhances current understanding of the morphological correlates of HD-OCT images in skin.

Holistic approach of pre-existing flaws on the decay of two limestones.

This study aims to understand the influence of the microfacies and the determination of pre-existing flaws on the weathering behavior of two types of limestones. Therefore, both Lede and Noyant limestones were independently weathered by strong acid tests and freeze-thaw cycles. In order to characterize the weathering patterns inside the stones, a combination of high resolution X-ray CT, SEM-EDS and thin section microscopy was used. The advantage of high resolution X-ray CT is its non-destructive character and the obtained 3D structural information. By using this technique, a time-lapse sequence of the weathering patterns was obtained for both gypsum crust formation as well as crack formation due to freezing and thawing. This way, a clear link could be made with the initial non-weathered state. Thin section microscopy and SEM-EDS provided additional chemical information. The focus of this study lies in the processes that occur in the bioclast fragments in the stone and the influence of the surrounding cement or matrix. The results show that weathering patterns vary for both limestones although the causes of weathering were similar. In case of the Noyant stone, the weathering by crystallizing gypsum was mainly restricted to the microporous matrix of the stone, while in case of the Lede stone, several foraminifera and shell fragments were preferentially recrystallized. In general, the underlying microstructure determines the weathering pattern of the stone.

Imaging of basal cell carcinoma by high-definition optical coherence tomography: histomorphological correlation. A pilot study.

BACKGROUND: With the continued development of noninvasive therapies for basal cell carcinoma (BCC) such as photodynamic therapy and immune therapies, noninvasive diagnosis and monitoring become increasingly relevant. High-definition optical coherence tomography (HD-OCT) is a high-resolution imaging tool, with micrometre resolution in both transversal and axial directions, enabling visualization of individual cells up to a depth of around 570 µm, and filling the imaging gap between conventional optical coherence tomography (OCT) and reflectance confocal microscopy (RCM). OBJECTIVES: We sought to determine the feasibility of detecting BCC by this technique using criteria defined for RCM and conventional OCT and compared with histology. METHODS: In this pilot study skin lesions of 21 patients with a histologically proven BCC were imaged by HD-OCT just before excision and images analysed qualitatively. RESULTS: Features for four different BCC subtypes were described in both transverse and axial directions. In general, these features were subepidermal or intradermal aggregations of cells. These islands or trabeculae were surrounded by a less refractile border corresponding with palisading and peritumoral mucin production. There was a pronounced architectural disarray of the epidermis. A variably refractile stroma together with abundant dilated peritumoral blood vessels was present. These features were comparable with histological features for each patient. CONCLUSIONS: Using features already suggested by RCM and conventional OCT, the study implies that HD-OCT facilitates in vivo diagnosis of BCC and allows the distinction between different BCC subtypes for increased clinical utility.

4D imaging and quantification of pore structure modifications inside natural building stones by means of high resolution X-ray CT.

Weathering processes have been studied in detail for many natural building stones. The most commonly used analytical techniques in these studies are thin-section petrography, SEM, XRD and XRF. Most of these techniques are valuable for chemical and mineralogical analysis of the weathering patterns. However, to obtain crucial quantitative information on structural evolutions like porosity changes and growth of weathering crusts in function of time, non-destructive techniques become necessary. In this study, a Belgian historical calcareous sandstone, the Lede stone, was exposed to gaseous SO(2) under wet surface conditions according to the European Standard NBN EN 13919 (2003). Before, during and after the strong acid test, high resolution X-ray tomography has been performed to visualize gypsum crust formation to yield a better insight into the effects of gaseous SO(2) on the pore modification in 3D. The tomographic scans were taken at the Centre for X-ray Tomography at Ghent University (UGCT). With the aid of image analysis, partial porosity changes were calculated in different stadia of the process. Increasing porosity has been observed visually and quantitatively below the new superficial formed layer of gypsum crystals. In some cases micro-cracks and dissolution zones were detected on the grain boundaries of quartz. By using Morpho+, an in-house developed image analysis program, radial porosity, partial porosity, ratio of open and closed porosity and equivalent diameter of individual pore structures have been calculated. The results obtained in this study are promising for a better understanding of gypsum weathering mechanisms, porosity changes and patterns on natural building stones in four dimensions.

Bluetongue virus type 17 can exist in a latent state in MDBK cells.

An infection with bluetongue virus type 17 can be regulated by the temperature of incubation to be either persistent, producing low levels of virus; lytic, producing a high titer of released virus; or latent, producing no detectable virus. The persistent and latent states are reversible.

Effects of ambient temperature on sexual maturity in chickens.

Ninety-six, 14-day-old Single Comb White Leghorns (48 males and 48 females) in each of two trials were divided into three groups and grown thereafter under one of the ambient temperatures of 21, 29, or 35 C. Age at sexual maturity of males was decreased in both trials as temperature was increased. First semen was produced at 54 and and 56 days of age in Trials 1 and 2, respectively, when the ambient temperature was 35 C and 68 and 63 days at 21 C for Trials 1 and 2, respectively. Sexual maturity of females was significantly delayed at the highest ambient temperature. Semen quality was only slightly affected by the highest ambient temperature. Although egg production was seriously affected at 35 C, fertility and hatchability, except in a few instances, were only mildly affected.

Effect of three lifetime ambient temperatures on growth, feed and water consumption and various blood components in male and female Leghorn chickens.

In two trials, SC White Leghorns were subjected to constant ambient temperatures of 21.1, 29.4, and 35.0 C from 2 to 31 or 32 weeks of age. Weekly measurements were made of body weight, feed efficiency, water consumption, red blood cell count, hemoglobin, hematocrit, total plasma protein, Po2, Pco2, pH, and mortality. It was found that the blood picture changes with age, sex, and ambient temperature. Age at which sex differences become significant varies with the blood component studied.

Electrolyte content of blood and bone in chickens subjected to heat stress.

In two trials, S. C. White Leghorns were subjected to constant ambient temperatures of 21.1, 29.4 and 35.0 C from 2 to 33 or 2 to 31 weeks of age. Blood samples were obtained 4 days prior to termination of the trial. In trial 1, blood electrolytes Na, K, Ca, Mg and Cl were studied. In trial 2, the same blood electrolytes plus P were studied and the left femur was analyzed for Na, K, Ca, Mg, P, Cu, Zn, Fe, Mn and % ash. Results indicate that both males and females can maintain homeostasis of both blood and bone under the above temperature conditions.

Growth and mineral content of cultured chick embryos.

In order to assess mineral uptake by chick embryos cultured outside of the shell, growth and mineral (Ca, Mg, K, Na) composition of control and cultured embryos and total egg contents (embryo plus residual egg contents) were measured from 8 through 21 days of incubation. At day nine and thereafter, cultured embryos contained significantly less Ca and Mg than did control embryos. At day 11 and thereafter, ash weight of cultured embryos was significantly less than that of controls. At 13 days and thereafter, wet weight, dry weight, toe length, K and Na content of cultured embryos were significantly less than in controls. To assess relative mineral uptake of cultured embryos, mineral (Ca, Mg, K, Na) content per gram embryo dry weight was plotted against incubation age. Values for the ratio of Mg, K and Na per gram dry weight were similar for control and cultured embryos. Control values for Ca per dry weight were consistently higher than those for cultured embryos during the period from 9 to 21 days. The data suggest that Ca may not be present in sufficient quantity, even on a relative growth basis, to perform its normal physiological functions in cultured embryos.

Growth of the chick embryo in vitro.

An improved technique is described for in vitro culture of the chick embryo from three days through 21 days of total incubation (three days in shell plus 18 days in culture). Mean survival time for cultured embryos is 18 days of total incubation, and mean morphological stage is Hamburger-Hamilton stage 41 (15 days). Mean measurements of wet weight, dry weight, and right third toe length for stage 45 (partial or complete abdominal yolk sac retraction, 19-20 days) cultured embryos are comparable with corresponding means for stage 42-43 (16-17 days) embryos from control intact eggs. Possible causes of growth retardation in vitro are briefly discussed.