IMAGE MAGNIFICATION IN DIGITAL FLUOROSCOPY

Image magnification is inherent in radiography. In digital fluoroscopy, the three components of magnification are geometric, electronic and photographic. In this study, the total magnification factor of a digital imaging system was determined by two methods, 1) comparison of measurements of a known object to its image and 2) calculation of geometric, electronic and photographic magnification from the imaging system specifications. Both methods were employed for various focal-film distances, image intensifier tube modes and laser printer formats. Results of these two methods were different due to the detrimental effect of penumbra on image quality with increasing magnification. If a radiographic image is to be used to approximate object size, then a technique should be used that will minimize magnification. In digital fluoroscopy this is achieved with the shortest object-film distance (assuming a fixed focal-object distance), largest image intensifler mode and greatest number of images per sheet of film.     

High Dynamic Range Image Fusion Based on Wavelet

With the developpment of image fusion technology and the maturity of wavelet theory, wavelet transform with its good time-frequency characteristics stands out in the field of image fusion. On the basis of wavelet transforms theory, this article proposes a high dynamic range imaging confusion method which combines with wavelet decomposition. First, perform a wavelet multi-scale decomposition to the two registered source image; then conduct wavelet inverse transform to the decomposed images. This paper focuses on the characteristics of high frequency and low frequency domain after wavelet decomposition,using different fusion methods in each of the frequency domain, finally obtain the fused image through inverse wavelet transform image reconstruction. The simulation results and evaluation index results show that, compared with other similar methods, this method is better in retaining the original image's details information, and improves the quality of fusion image.     

Preparation of muscle samples for comparative electron microscopy.

The interpretation of muscle structure by scanning electron microscopy (SEM) has not been consistent among various studies. Consequently, the literature is confusing with respect to the identity of T-tubules, transverse ridges, Z-disks, and intermyofibrillar connections. The objective of this research was to evaluate the effects of different methods of sample preparation and imaging on ultrastructural details of previously identified transverse structures and intermyofibrillar connections and to verify or disprove the commonality of these structures under different viewing conditions. Scanning electron microscopy coupled with a cold stage, SEM at room temperature, and transmission electron microscopy (TEM) of thin sections were most appropriate for exposing detail of inter- and intracellular structures and for measuring sarcomere length and spacing of intermyofibrillar connections. Scanning electron microscopy of samples mounted on a cold stage, fractured, and sublimed provided excellent images of meat and muscle ultrastructure and may be used in correlative microscopy. Sarcomere length and spacing between intermyofibrillar connections were similar among most specimen preparation techniques and were affected similarly by heat treatments. Results indicate that the regularly spaced transverse structures viewed by conventional SEM and the intermyofibrillar connections viewed by low-temperature SEM are Z-disks.     

Radiography, myelography, computed tomography, and magnetic resonance imaging of the spine.

Various methods of documenting pathologic change in the spine and spinal cord are available to the veterinary practitioner. Intimidation caused by the imaging modality and the fear that one will not be able to recognize or diagnose a lesion are the factors that limit the use of diagnostic imaging. One needs only to be able to recognize the variations of normal anatomy to be successful. Once an abnormal area has been identified, the diagnosis is soon to follow. Therefore one should concentrate on improving the simple skills associated with image interpretation and normal anatomy. Lesion identification and definitive diagnoses will follow by natural progression.     

基于灵活的时空融合模型的植被覆盖度与植被指数关系

时空数据融合模型被广泛地应用于获取高时间、高空间分辨率的植被指数与植被覆盖度,但是其反演的精度常常受输入的低空间分辨率影像(如MODIS影像)的影响。本研究基于灵活的时空数据融合方法(FSDAF),深入分析了赛里木湖流域与石河子地区两种不同情景的MODIS影像组合对FSDAF模型植被覆盖度提取精度的影响,并研究了6种植被指数与植被覆盖度的线性与非线性关系。研究结果表明,FSDAF模拟影像的植被覆盖度精度取决于2个时期MODIS影像的变化率,影像变化小时取得的精度明显好于影像差异大的情况。而采用植被指数对植被覆盖度模拟时,NDVI与OSAVI的线性拟合效果较好,可以获取较理想的结果。试验表明,采用时空模型用于研究区植被覆盖反演能取得较好的效果,具有一定的应用推广价值。     

COMPARISON OF FAST SPIN-ECHO AND CONVENTIONAL SPIN-ECHO MAGNETIC RESONANCE SPINAL IMAGING TECHNIQUES IN FOUR NORMAL DOGS

Various magnetic resonance (MR) imaging techniques have been used to assess lumbar spinal abnormalities in people. Four, young adult, clinically normal dogs were used to compare images of the spinal cord acquired using conventional spin-echo and rapid acquisition relaxation-enhanced (RARE), commonly called fast spin-echo (FSE), magnetic resonance imaging techniques. Lateral myelograms were made as an anatomic control. The T2-weighted FSE technique was characterized by better image quality than the T2-weighted conventional spin-echo technique. The short acquisition time with the FSE technique allowed increases in the matrix size and number of excitations, thus improving resolution and signal-to-noise ratio. In canine lumbar spinal MR imaging, use of a FSE technique is recommended to reduce the overall time for imaging and to improve image quality.     

Technique for transrectal ultrasonography of the cranial mesenteric artery of the horse

Transrectal ultrasonography was successfully used to image the cranial mesenteric artery and its branches in 23 adult horses. The artery could be imaged from its origin at the aorta distally to identify several bifurcations. The method for transrectal imaging of the cranial mesenteric artery and its major branches required 3 distinct transducer positions. One position was used to locate the cranial mesenteric artery by imaging the caudal portion of the aorta from the aortic bifurcation cranially to the level of the cranial mesenteric artery. The second position was used to image the origin of the cranial mesenteric artery. The third position was used to image the major branches of the cranial mesenteric artery.     

IMAGING: RADIOGRAPHY-11*

In this paper an overview of principles involved in radiographic imaging by tomography, magnification radiography, xeroradiography, and computed tomography is presented. Tomography is a method to selectively blur distracting superimposed shadows while maintaining relative image sharpness in a plane of concern. Magnification radiography is a method to directly enlarge the radiographic image by increasing object-film distance and utilizing a small focal spot. Xeroradiography is an electrostatic imaging process that provides wide latitude and good resolution through enhanced contrast in tissues with poor inherent contrast. Computed tomography involves imaging by computer analysis of x-ray absorption utilizing rotational x-ray projections.     

3-dimensional imaging modalities for phenotyping genetically engineered mice

A variety of 3-dimensional (3D) digital imaging modalities are available for whole-body assessment of genetically engineered mice: magnetic resonance microscopy (MRM), X-ray microcomputed tomography (microCT), optical projection tomography (OPT), episcopic and cryoimaging, and ultrasound biomicroscopy (UBM). Embryo and adult mouse phenotyping can be accomplished at microscopy or near microscopy spatial resolutions using these modalities. MRM and microCT are particularly well-suited for evaluating structural information at the organ level, whereas episcopic and OPT imaging provide structural and functional information from molecular fluorescence imaging at the cellular level. UBM can be used to monitor embryonic development longitudinally in utero. Specimens are not significantly altered during preparation, and structures can be viewed in their native orientations. Technologies for rapid automated data acquisition and high-throughput phenotyping have been developed and continually improve as this exciting field evolves.     

A TECHNIQUE FOR MAGNETIC RESONANCE IMAGING OF EQUINE CADAVER SPECIMENS

We tested an adaptation of a technique for performing magnetic resonance (MR) imaging of human cadaver limbs in the horse. The forelimbs from a normal horse were collected, frozen, and sealed with a paraffin-polymer combination prior to imaging with either a high- or midfield magnetic resonance scanner. Each forelimb was defrosted, scanned, and refrozen on two separate occasions. A five-point scale was used to evaluate the quality of each set of sagittal and transverse, T1-weighted images of each digit. There was no difference in image quality between first and second scans of either specimen (p > 0.05). We conclude that this technique allows investigators to bank tissue specimens for future magnetic resonance imaging without significant loss of image quality.     

Comparison of different methods to assess the composition of pig bellies in progeny testing

The objective of the study was to validate methods that assess the belly composition of stationary tested progenies of Piétrain boars. In German performance test stations, there are currently three methods of determining belly compositon in use: 1) a regression equation that contains different carcass characteristics, such as fat thickness and muscle area; 2) planimetric analysis of video or digital images acquired at the cut between the 13th and 14th ribs; and 3) estimation of the belly composition using ultrasound data from a three-dimensional ultrasound image produced an online carcass-grading system. Validation of these techniques was performed on 400 carcasses of stationary-tested Piétrain and Piétrain-sired crossbred pigs, which were slaughtered at a mean carcass weight of 85 and 97 kg. Magnetic resonance imaging (MRI) served as a reference to determine the lean content of the bellies. The correlation to MRI lean content ranged from 0.71 to 0.81, and corresponding correlation values were 0.62 to 0.64 for the digital imaging technique, and 0.53 to 0.59 for the AutoFOM online carcass-grading system. An increase in precision was achieved when information from digital imaging and linear carcass measures were included in the regression equation. Accuracy of the AutoFOM system does not seem to be sufficient to assess the belly composition for the special breeds in performance testing. However, extracting and combining 127 AutoFOM-base recordings into modified equations using partial least squares techniques yielded an improvement in the prediction accuracy for all tested breed and/or weight groups.     

雌雄蚕卵激光自动分选仪的工作原理和基本结构与设计思路

为促进雄蚕品种的选育与繁育推广,研制成功了雌雄蚕卵激光自动分选仪。该仪器可依据雄蚕品种雌雄蚕卵具有不同卵色的特点,通过图像采集和计算机图像处理及识别,指令激光器精确地射杀雌卵,从而只保留雄卵,为雄蚕品种的选育和繁育推广提供了快速精确的分卵设备与方法,解决了人工分选雌雄蚕卵效率低的难题。重点阐述了该仪器的工作原理和蚕卵图像的计算机处理软件等部分的设计思路,介绍了仪器的基本结构与基本配置及主要工作流程,以及分选平附种和散制种蚕卵的方法与主要的技术参数。     

Differential expression and localization of TRPV channels in the mature sperm of Anas platyrhynchos

Sperm cells perform precise chemotactic and thermotactic movement which is crucial for fertilization. However, the key molecules involved in detection of different chemical and physical stimuli which guide the sperm during navigation are not well understood. Ca²⁺-signalling mediated by ion channels seem to play important role in motility and other fertility parameters. In this work, we explored the endogenous localization pattern of TRPV channels in the mature spermatozoa of avian species. Using sperm from white pekin duck (Anas platyrhynchos) as the representative avian model, we demonstrate that duck sperm endogenously express the thermosensitive channels TRPV1, TRPV2, TRPV3, TRPV4, and highly Ca²⁺-selective channels TRPV5 and TRPV6 in specific yet differential locations. All of these TRPV channels are enriched in the sperm tail, indicating their relevance in sperm motility. Interestingly, the TRPV3 and TRPV4 channels are present in the mitochondrial region. Calcium selective TRPV5 channel is exclusively present in sperm tail and is most abundant among the TRPV channels. This is the first report describing the endogenous presence of TRPV2 and TRPV3 channels in the sperm of any species. Using confocal imaging and super-resolution imaging, we demonstrate that though the TRPV channels are evolutionarily closely related, they have distinct localization pattern in the duck sperm, which could impact their role in fertilization.     

The use of magnetic resonance imaging for the assessment of distal limb wounds in horses: A pilot study

The utility of magnetic resonance (MR) imaging in the evaluation of equine solar foot penetrations is well established. The objective of this pilot study was to evaluate the utility of MR imaging in assessment of equine distal limb wounds excluding solar penetrations. Low-field MR images of 23 horses that had previously sustained distal limb wounds were reviewed in consensus by two ECVDI diplomats. Structures (bone; synovial structure; subcutaneous tissue and skin; and ligament/tendon) were identified as normal or abnormal on MR images, radiographs and ultrasound images and reports. All abnormalities were described. The presence of artefacts and their effect on image interpretation were also noted for each modality. Comparisons were made between imaging modalities, and it was noted if MR imaging influenced case management. Abnormalities of the bone were identified in 26% of horses on MR images and 17% of horses on radiographs; there were no osseous abnormalities identified on radiographs that were not identified on MR images, and additional features and better characterisation of lesions were noted on MR images. Tendon/ligament abnormalities were identified in 57% horses on MR and 47% of horses on ultrasound images. Magnetic susceptibility artefacts compromised MR image interpretation in 17% of horses. MR imaging of equine distal limb wounds allowed identification of both osseous and tendon/ligament abnormalities in more cases than either radiography or ultrasonography, and altered case management in 20/23 horses. Although MR imaging should not replace conventional imaging, this study highlights that MR imaging of equine distal limb wounds can yield information not detected on conventional imaging which may direct treatment and affect prognostication.     

COMPUTED TOMOGRAPHIC IMAGING OF DOGS WITH PRIMARY LARYNGEAL OR TRACHEAL AIRWAY OBSTRUCTION

Seventeen dogs with clinical signs attributable to nonneoplastic obstruction of the larynx, trachea, or large bronchi underwent computed tomography (CT) imaging. In 16 of the 17 dogs, CT was performed without general anesthesia using a positioning device. Fifteen of these 16 dogs were imaged without sedation or general anesthesia. Three‐dimensional (3D) internal rendering was performed on each image set based on lesion localization determined by routine image planes. Visual laryngeal examination, endoscopy, video fluoroscopy, and necropsy were used for achieving the cause of the upper airway obstruction. The CT and 3D internal rendering accurately indicated the presence and cause of upper airway obstruction in all dogs. CT findings indicative of laryngeal paralysis included failure to abduct the arytenoid cartilages, narrowed rima glottis, and air‐filled laryngeal ventricles. Laryngeal collapse findings depended on the grade of collapse and included everted laryngeal saccules, collapse of the cuneiform processes and corniculate processes, and narrowed rima glottis. Trachea abnormalities included hypoplasia, stenosis, or collapse syndrome. The CT findings in tracheal hypoplasia consisted of a severely narrowed lumen throughout the entire length. Tracheal stenosis was represented by a circumferential decrease in tracheal lumen size limited to one region. Tracheal collapse syndrome was diagnosed by severe asymmetric narrowing. Lobar bronchi collapse appeared in CT images as a narrowed asymmetric lumen diameter. CT imaging of unanesthetized dogs with upper airway obstruction compares favorably with traditional definitive diagnostic methods.     

IMAGING ARTIFACTS IN DIAGNOSTIC ULTRASOUND—A REVIEW

Imaging artifacts commonly occur during routine ultrasonographic evaluation of patients and contribute to image inaccuracies. These artifacts are classified into artifacts arising from factors controllable prior to imaging or from sound beam interactions within the patient which may result in clinically useful or confusing artifacts. Artifact formation, and how this influences the anatomical image location, echogenicity, size and shape, is described. The clinical interpretation of artifacts is explained in order to gain maximum diagnostic information from an ultrasonographic image.     

Radiographic contrast study of the upper gastrointestinal tract of eight dogs using carboxymethylcellulose mixed with a low concentration of barium sulphate

To evaluate the efficacy of a mixture of barium and carboxymethylcellulose (CMC) suspension in upper gastrointestinal contrast studies, and to determine its optimal concentration and method for use, eight healthy beagle dogs underwent conventional upper gastrointestinal contrast imaging and a modified procedure using a mixture of barium sulphate and CMC. Four different procedures were carried out on the dogs at weekly intervals. In the first, the dogs were administered 10 ml/kg of 60 per cent barium suspension for conventional study of the upper gastrointestinal tract. The second, third and fourth procedures involved modified methods in which the dogs were given 10 ml/kg of a mixture of 25 per cent barium and 0.5 per cent CMC prepared to a low, moderate or high viscosity, respectively. All four procedures were evaluated by four criteria: the quality of the images obtained, the translucency and distensibility of the bowel, and the transit time. The method of imaging which used a moderately viscious CMC formulation provided excellent image quality, high translucency, a rapid transit time and suitable bowel distension to enable more precise diagnosis of disorders of the gastrointestinal tract.     

MAGNETIC RESONANCE IMAGING OF THE CANINE BRAIN AT 3 AND 7 T

Magnetic resonance (MR) imaging of the canine brain is commonly acquired at field strengths ranging from 0.2 to 1.5 T. Our purpose was to compare the MR image quality of the canine brain acquired at 3 vs. 7 T in dogs. Low‐resolution turbo spin echo (TSE) T2‐weighted images (T2W) were obtained in transverse, dorsal, and sagittal planes, and high‐resolution TSE T2W and turbo spin echo proton density‐weighted images were obtained in the transverse and dorsal planes, at both 3 and 7 T. Three experienced reviewers evaluated 32 predetermined brain structures independently and without knowledge of field strength for spatial resolution and contrast. Overall image quality and evidence of artifacts were also evaluated. Contrast of gray and white matter was assessed quantitatively by measuring signal intensity in regions of interest for transverse plane images for the three pulse sequences obtained. Overall, 19 of the 32 neuroanatomic structures had comparable spatial resolution and contrast at both field strengths. The overall image quality for low‐resolution T2W images was comparable at 3 and 7 T. High‐resolution T2W was characterized by superior image quality at 3 vs. 7 T. Magnetic susceptibility and chemical shift artifacts were slightly more noticeable at 7 T. MR imaging at 3 and at 7 T provides high spatial resolution and contrast images of the canine brain. The use of 3 and 7 T MR imaging may assist in the elucidation of the pathogenesis of brain disorders, such as epilepsy.     

INVITED REVIEW—IMAGE REGISTRATION IN VETERINARY RADIATION ONCOLOGY: INDICATIONS,IMPLICATIONS, AND FUTURE ADVANCES

The field of veterinary radiation therapy (RT) has gained substantial momentum in recent decades with significant advances in conformal treatment planning, image‐guided radiation therapy (IGRT), and intensity‐modulated (IMRT) techniques. At the root of these advancements lie improvements in tumor imaging, image alignment (registration), target volume delineation, and identification of critical structures. Image registration has been widely used to combine information from multimodality images such as computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) to improve the accuracy of radiation delivery and reliably identify tumor‐bearing areas. Many different techniques have been applied in image registration. This review provides an overview of medical image registration in RT and its applications in veterinary oncology. A summary of the most commonly used approaches in human and veterinary medicine is presented along with their current use in IGRT and adaptive radiation therapy (ART). It is important to realize that registration does not guarantee that target volumes, such as the gross tumor volume (GTV), are correctly identified on the image being registered, as limitations unique to registration algorithms exist. Research involving novel registration frameworks for automatic segmentation of tumor volumes is ongoing and comparative oncology programs offer a unique opportunity to test the efficacy of proposed algorithms.     

Diagnostic imaging – evaluating image quality using visual grading characteristic (VGC) analysis

Radiologists are regularly faced with the task of comparing image quality obtained using different imaging systems or settings. Visual grading techniques can be used to evaluate the quality of images by grading the clarity of reproduction of anatomical or pathological structures. The methods, which include “visual grading analysis (VGA)” and the “image criteria (IC) study”, are characterised by their attractive simplicity and reliability. Non-parametric rank-invariant statistical methods are suitable techniques for statistical analysis of VGA-data. Båth and Månsson (2007) introduced such a method and termed it “visual grading characteristics (VGC) analysis”. This paper gives an overview of the principle together with an example of its use in veterinary radiology. The aim of this review article is to encourage veterinary researchers to apply this method which has proven valuable in the human field. Basically, the method can also be applied for the analysis of other categories of images (e.g. histological sections, cytological smears) in cases where the task is to evaluate features subjectively on the basis of a score, allowing some degree of freedom of decision. Furthermore, the aim of the investigation is not necessarily restricted to quality aspects. Other questions such as the effects of treatment options on the appearance of certain structures can be compared as well.