COMPARISON OF SINGLE-SLICE COMPUTED TOMOGRAPHY PROTOCOLS FOR DETECTION OF PULMONARY NODULES IN DOGS

Two dogs (4 and 38 kg) with radiographic evidence of pulmonary nodules were evaluated using single-slice, helical computed tomography (CT). Each thorax was scanned using 12 combinations of examination parameters that included slice collimation width (3 and 5 mm for the small dog and 5 and 7 mm for the large dog), pitch (1, 1.5, and 2), and reconstruction interval (0.5 and 1). Sensitivity, specificity, and accuracy for nodule detection were evaluated for each protocol by three different observers, their results being compared with a consensus evaluation of images acquired with the protocol providing the best theoretic resolution (narrow collimation, pitch of 1, reconstruction interval of 0.5). For all observers, sensitivity and accuracy were significantly increased when using a protocol with narrow collimation ( P <0.0001–0.005 and P =0.0003–0.005, respectively). Pitch and reconstruction interval did not significantly influence the accuracy, sensitivity, or specificity for at least two of the observers. Additionally, nodule size (<3 mm vs. ≥3 mm) did not significantly affect nodule detection. Interobserver repeatability was variable among protocols (κ=0.32–0.78), highlighting the fact that nodule detection may be more dependent on the observer than on the choice of the CT protocol. For single-slice CT, the results of this study suggest that narrow collimation (3–5 mm, depending on the animal's size), a pitch of 2 and a reconstruction interval of 1 should be used in dogs for the detection of pulmonary nodules.     

QUANTITATIVE COMPUTED TOMOGRAPHY EVALUATION OF PULMONARY DISEASE

Objective assessment of pulmonary disease from computed tomography (CT) examinations is desirable but difficult. When such assessments can be made, it is important that they are related to some part of the pathophysiologic process present. Herein we propose that automated volume histogram analysis can yield data that allow differentiation of normal from abnormal lung, and that the magnitude of disease will have an association with objective CT indices. Data from pulmonary CT images from 34 foxes (six uninfected controls and 28 infected with Angiostrongylus vasorum , subdivided by age and infective dose) were available. Lung tissue was segmented from surrounding tissue using an automated segmentation method. A volume histogram showing voxel frequency for each CT number in the range −1024 to −250 HU was created from the entire image stack from each fox. Using these data, the inter-quartile range and the CT number at the 95th percentile were determined. The results showed that segmentation could be readily achieved but that areas of severely diseased lung were excluded. Based on two-way analysis of variance for both the inter-quartile range and the CT number at the 95th percentile, both quantities were significantly affected by the infection status of the animal and were related to worm burden ( P <0.001). The study shows that this form of analysis is readily achieved and provides quantitative data that can be used to assess disease severity, progression, and response to treatment.     

Morphological and histological characterization of an ectopically mineralized structure in a gilthead sea bream Sparus aurata with opercular deformation

In this study, we describe an abnormal ectopically mineralized structure (EMS) that was found inside the skull of a juvenile Sparus aurata that also showed a bilateral opercular deformation. The overall phenotype and tissue composition were studied using micro‐CT scanning and histological analyses. The ectopic structure occupies a large volume of the brain cavity, partially extruding into the gill cavity. It shows a dense mineralization and an extracellular matrix‐rich phenotype, with variation in both the morphology and size of the cell lacunae, combined with an irregular fibre organization inside the matrix. This study is the first to report such an EMS in a juvenile teleost fish, where the tissue does not resemble any other connective tissue type described in bony fish so far. The tissue phenotype seems to rule out that the EMS corresponds to a tumorous cartilage. Yet, it is rather reminiscent of a highly mineralized structure found in cartilaginous fish, where it is suggested to be associated with damage repair.     

Computed tomographic contrast tenography of the digital flexor tendon sheath of the equine hindlimb

Pre‐surgical investigation of digital flexor tendon sheath pathology remains challenging with current standard imaging techniques. The aim of this prospective, anatomical, pilot study was to describe the anatomy of the equine hind limb digital flexor tendon sheath using a combination of computed tomography (CT) and computed tomographic contrast tenography in clinically normal cadaver limbs. Ten pairs of hind limbs with no external abnormalities were examined from the level of the tarsometatarsal joint distally. Limbs initially underwent non‐contrast CT examination using 120 kVp, 300 mAs, and 1.5 mm slice thickness. Sixty millilitres of ioversol iodinated contrast media and saline (final concentration 100 mg/ml) were injected using a basilar sesamoidean approach. The computed tomographic contrast tenography examination was then repeated, before dissection of the specimens to compare gross and imaging findings. The combined CT and computed tomographic contrast tenography examinations provided excellent anatomical detail of intra‐thecal structures. The borders of the superficial and deep digital flexor tendons, and the manica flexoria were consistently identifiable in all limbs. Detailed anatomy including that of the mesotenons, two of which are previously undescribed, and the plantar annular ligament were also consistently identifiable. Dissection of all 10 pairs of limbs revealed there to be no pathology, in accordance with the imaging findings. In conclusion, the combination of CT and computed tomographic contrast tenography may be useful adjunctive diagnostic techniques to define digital flexor tendon sheath pathology prior to surgical exploration in horses.     

玉米象各发育期对磷化氢的敏感性

结果表明,磷化氢对玉米象(Sitophilus zeamais Motschlscky)成虫有较强的毒力。玉米象各发育期对磷化氢的敏感性为:成虫>幼虫>卵>蛹,幼虫的耐药力与成虫接近,卵与蛹的耐药力几乎相同,卵、蛹的耐药力比成虫、幼虫约大2倍。因此,磷化氢熏蒸效果检查,不仅应对所有虫态检查,而且应保持储粮中较长时间没有活虫发生;在保持磷化氢有效浓度条件下,增加暴露时间能增效;CT值能全面检查磷化氢实仓熏蒸效果。未来用CT值代替剂量值,对进一步改善磷化氢熏蒸技术和提高药效,具有重要的现实意义。     

深松结合秸秆还田对黑土孔隙结构的影响

【目的】东北黑土实施深松结合秸秆还田对土壤孔隙结构影响的研究缺乏明确性结论，为此开展本研究，旨在研究深松结合秸秆还田对黑土结构的影响机制，为合理耕层创建提供科学依据。【方法】利用在东北典型黑土区——黑龙江省绥化市青冈县开展的5年田间定位试验为平台，设置农民常规耕作（FP）、单独深松25 cm(T2)、深松25 cm结合秸秆还田（T3）和深松35 cm结合秸秆还田（T4）等处理，采用CT扫描技术开展土壤孔隙结构可视化和定量化研究，并结合田间持水量和容重等指标，探究深松结合秸秆还田对黑土孔隙结构的影响。【结果】通过土壤孔隙二维和三维图像可以清晰看出，各处理0—20 cm土层孔隙分布均明显少于20—40 cm土层，深松结合秸秆还田（T3、T4）的孔隙分布明显多于FP，增加了结构更为复杂的大孔隙。定量化分析表明，相较于FP，单独深松25 cm(T2)显著提高20—30 cm土层总孔隙度103.0%(P<0.05)，主要通过显著提高小孔隙（孔隙直径d≤0.50 mm）孔隙度91.3%和中孔隙（0.50 mm相似文献   

Comparison of X-ray CT and MRI of watercore disorder of different apple cultivars

Watercore is an internal disorder that appears as water-soaked, glassy regions near the core in apples. Fast and non-destructive solutions for sensing watercore would be readily accepted in the postharvest industry. X-ray CT and MRI were compared as potential imaging technologies for detecting this particular disorder. After matching the 3D datasets of X-ray CT and MRI, the images that were obtained on identical fruit were compared quantitatively. Both MRI and CT were able to detect watercore, however the contrast in MRI images was superior. High-resolution micro-CT images showed the microstructural changes in watercore fruit: the intercellular spaces of the affected apple tissue are filled with water. This explained the higher density that is detected here by the X-rays and the higher water content in the MRI. Mean and variance of the frequency distribution of MRI and X-ray CT intensity appeared to be a parameter that allows the identification of healthy apples from affected fruit. Automatic image processing based on thresholding the images resulted in comparable watercore classification accuracy of up to 89% for X-ray CT and 79% for MRI data, despite the better contrast in the MRI images.     

基于CT扫描的不同粒形滤料孔隙结构特征

滤层孔隙结构直接影响过滤过程中的颗粒沉积和运移效果。为了掌握砂石过滤器不同粒形滤料组成滤层的内部孔隙结构特征，该研究以粒径为1～1.18 mm的普通石英砂（QS1）、天然海砂（SS2）、改性玻璃（MG3）和玻璃微珠（GB4）4 种滤料为研究对象，采用CT 扫描技术对滤层孔隙模型进行了三维重构，利用VGStudio MAX、Image J等计算机图像处理软件，分析了 4 种滤层的孔隙率、孔径大小及孔隙形状参数，并结合分形理论确定了 4 种滤层孔隙结构的计盒分形维数。结果表明：4种滤层的表观孔隙率范围分别为0.397～0.446（QS1）、0.385～0.423（SS2）、0.407～0.456（MG3）、0.351～0.380（GB4），对应体积孔隙率分别为0.422、0.412、0.441、0.366；对应孔径范围分别为75～960、80～760、70～1 050、85～930 μm，圆度值区间分别为1.59～1.78、1.35～1.54、1.65～2.03、1.20～1.36，扁平度值区间分别为2.62～2.75、2.05～2.20、3.04～3.21、1.94～2.04，计盒维数均值分别为1.621、1.566、1.661、1.446。该研究定量表征了滤层孔隙结构特性，得出不同粒形滤料细观孔隙结构的差异：滤层表观孔隙率呈现"上高下低"分布规律，孔径分布规律表明滤层内均是小孔隙占多数，大孔隙占少数，且孔隙以狭长型为主。随着滤料棱角度增加，表观孔隙率分布越分散，体积孔隙率越大，大孔隙占比也相应增加，最大达到17.24%（MG3），孔隙形状更加偏离球形，表征孔隙结构复杂性的计盒维数相应增加，且分形维数与孔隙率呈负相关关系。滤层孔隙结构研究可为后续研究滤层内颗粒沉积和运移规律奠定基础。     

Microstructural characterisation of commercial kiwifruit cultivars using X-ray micro computed tomography

The skin is the physical barrier between the fruit and the environment in which it develops. Environmental conditions during fruit development have a large influence on fruit quality, both at the time of harvest and during subsequent storage. It is hypothesised that some features of the skin and sub-epidermal tissues could provide information about the past growing conditions to which the fruit was exposed and therefore be of predictive value for storage quality. In this study, five commercial kiwifruit cultivars (‘Hayward’, ‘Hort16A’, ‘G3’, ‘G9’ and ‘G14’) were studied, and ‘Hayward’ fruit were manipulated during growth with different cultural practices. After harvest at horticultural maturity, X-ray micro computed tomography (μCT) was used to investigate features of the skin and the immediate parenchyma tissue. Despite orchard management practices (crop load and girdling) being observed to effect macro fruit quality parameters (mass, firmness, SSC, and DM), differences in microstructure (e.g. porosity) caused by these practices were not observed. However, porosity and pore size were found to be highly variable between cultivars. The thickness of dense sub-epidermal tissue could be readily measured and the 3-D distribution of raphide bundles was visible as high density particles distributed within the parenchyma. Overall, μCT was found to be a powerful technique to explore fruit epidermal and sub-epidermal structures in three dimensions at a micro level. However, the length of time required for data capture and analysis and the large number of samples required to overcome natural variation within horticultural products need to be considered. Future work may define the impact of differences in porosity or sub-epidermal anatomy on kiwifruit physiology (e.g. firmness change or sensitivity to low oxygen storage atmospheres). With this information, μCT could be used as a screening tool during plant breeding, or to determine the response to agronomic treatments, without conducting lengthy storage trials.