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1.
Computed tomography (CT) is commonly used in veterinary practice to evaluate dogs with suspected brain disease, however contrast resolution limitations and artifacts may reduce visualization of clinically important anatomic features. The purpose of this study was to develop an optimized CT protocol for evaluating the canine brain. The head of a 5‐year‐old Springer Spaniel with no neurological signs was imaged immediately following euthanasia using a 4‐slice CT scanner and 282 protocols. Each protocol used a fixed tube voltage of 120 kVp and 10 cm display field of view. Other acquisition and reconstruction parameters were varied. For each protocol, four selected images of the brain were reconstructed, anonymized and saved in DICOM format. Three board‐certified veterinary radiologists independently reviewed each of the four images for each protocol and recorded a numerical quality score for each image. The protocol yielding the lowest total numerical score was defined as the optimal protocol. There was overall agreement that the optimal protocol was the one with the following parameters: sequential mode, 300 mAs, 1 mm slice thickness, 1 s tube rotation time, medium image reconstruction algorithm and applied beam hardening correction. Sequential imaging provided optimal image resolution. The thin‐sliced images provided a small blur due to partial volume artifacts. A high tube current resulted in a relatively low noise level. Use of a medium frequency image reconstruction algorithm provided optimal contrast resolution for brain tissue. Use of a proprietary beam hardening correction filter (Posterior Fossa Optimization) markedly reduced beam‐hardening artifact.  相似文献   

2.
Karen L.  Morrow  DVM  MS  Richard D.  Park  DVM  PhD  Thomas L.  Spurgeon  PhD  Ted S.  Stashak  DVM  MS  Billie  Arceneaux  RT 《Veterinary radiology & ultrasound》2000,41(6):491-497
The head from three horses euthanized due to diseases unrelated to the head and neck was imaged using computed tomography (CT). Gross cross-sectional slices of equine head #1 and skeleton of equine head #2 were compared with the CT images of the three equine heads to identify normal structures of the cranium, brain, paranasal sinuses, nasal cavity, and teeth. Labeled transverse CT images of the equine head are presented sequentially as a reference for normal anatomy.  相似文献   

3.
The VetMousetrap?, a novel device that allows computed tomography (CT) of awake cats and provides a clinically supportive environment, is described. Ten normal cats were used to test the device for ambient internal oxygen, carbon dioxide levels, and temperature. Twenty‐two awake normal cats were imaged using a 16‐multi‐slice helical CT unit to evaluate dose‐equivalent protocols. Two different X‐ray tube potentials (kV), 80 and 120, and two different helical pitches, 0.562 and 1.75, were evaluated. The signal intensity of the pulmonary parenchyma (SIlung), signal intensity of background (SIbackgr), contrast, noise, signal‐to‐noise ratio (SNR), and contrast‐to‐noise ratio (CNR) were calculated. Three evaluators ranked the images for sharpness of liver margins, motion, helical, and windmill artifacts. CT was successfully completed in 20 of 22 cats. No artifacts directly related to the device were detected. Overall, 75 of 80 (94%) examinations were judged to have absent or minimal motion artifact. A statistically significant difference was found for SNR (P=0.001) and CNR (P=0.001) between all protocols. The higher pitch protocols had significantly lower noise and higher SNR and CNR, lower motion artifact but greater helical artifacts. A protocol using 80 kV, 130 mA, 0.5 s, and 0.562 pitch with 1.25 mm slice thickness, and 0.625 mm slice reconstruction interval is recommended. The VetMousetrap? appears to provide the opportunity for diagnostic CT imaging of the thorax of awake cats.  相似文献   

4.
The heads of three loggerhead sea turtles were disarticulated and imaged immediately to minimize postmortem changes and then frozen and sectioned. For computed tomography (CT) imaging, the heads were positioned in ventral recumbency. Transverse CT images with soft-tissue window were obtained from the olfactory sac region to the temporomandibular joint region. After CT imaging, the heads were sectioned and the gross sections were compared to CT images, to assist in the accurate identification of the anatomic structures. Different clinically relevant anatomic structures were identified and labelled in two series of photographs (CT images and anatomic cross-sections). CT images provided good differentiation between the bones and the soft tissues of the head. The information presented in this paper should serve as an initial reference to evaluate CT images of the head of the loggerhead sea turtle and to assist in the interpretation of lesions of this region.  相似文献   

5.
A series of CT imaging experiments was performed to test the hypothesis that when the tympanic bulla is filled with fluid there would be a false impression of bulla wall thickening. CT images were obtained before and after introduction of water in the tympanic bulla of a fresh canine cadaver. Images were acquired using different mA settings, slice thicknesses, reconstruction algorithms, and displayed at different window widths. The wall of the fluid filled bulla appeared thicker than that of the air filled bulla. This artifact was also demonstrated on a phantom composed of a thin (0.5 mm) and a thick (5 mm) piece of aluminum imaged in air and water. The effect was more apparent when images were acquired as thick slices (>5 mm), reconstructed with a soft tissue algorithm, or displayed with a narrow window (<250 CT numbers). The radiologist must be aware of this artifact when interpreting CT images of the tympanic bullae.  相似文献   

6.
Turbinate destruction is an important diagnostic criterion in canine and feline nasal computed tomography (CT). However decreased turbinate visibility may also be caused by technical CT settings and nasal fluid. The purpose of this experimental, crossover study was to determine whether fluid reduces conspicuity of canine and feline nasal turbinates in CT and if so, whether CT settings can maximize conspicuity. Three canine and three feline cadaver heads were used. Nasal slabs were CT‐scanned before and after submerging them in a water bath; using sequential, helical, and ultrahigh resolution modes; with images in low, medium, and high frequency image reconstruction kernels; and with application of additional posterior fossa optimization and high contrast enhancing filters. Visible turbinate length was measured by a single observer using manual tracing. Nasal density heterogeneity was measured using the standard deviation (SD) of mean nasal density from a region of interest in each nasal cavity. Linear mixed‐effect models using the R package ‘nlme’, multivariable models and standard post hoc Tukey pair‐wise comparisons were performed to investigate the effect of several variables (nasal content, scanning mode, image reconstruction kernel, application of post reconstruction filters) on measured visible total turbinate length and SD of mean nasal density. All canine and feline water‐filled nasal slabs showed significantly decreased visibility of nasal turbinates (P < 0.001). High frequency kernels provided the best turbinate visibility and highest SD of aerated nasal slabs, whereas medium frequency kernels were optimal for water‐filled nasal slabs. Scanning mode and filter application had no effect on turbinate visibility.  相似文献   

7.
Laser rhinoscopy was used to treat a nasal obstruction in a captive California sea lion (Zalophus californianus). The rehabilitated, adult, female sea lion developed mucopurulent, intermittent, bilateral nasal discharge and functional nasal obstruction 20 mo after acquisition by the Aquarium of the Pacific in Long Beach, California. A 3-mm-thick soft tissue structure spanning the region between the soft and hard palates, a deviated nasal septum, and several nasopharyngeal polyps were identified. Biopsies and cultures of the obstructive web showed ulcerative granulation tissue with suppurative inflammation, bacterial infection, and a partial section of an arthropod larva (not speciated). Laser rhinoscopy was performed to relieve the caudal nasopharyngeal obstruction and ablate the polyps. The sea lion appeared to breathe through the nares with lessened nasal discharge for a period of 6 wk after laser therapy, but within 8 wk the mucopurulent nasal discharge returned, the obstruction had reformed, and the sea lion was euthanized. Postmortem examination confirmed antemortem diagnoses of caudal nasopharyngeal obstruction secondary to inflammatory tissue; however, no additional sections of arthropod parasites were located microscopically.  相似文献   

8.
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9.
The purpose of this study was to develop an optimized imaging protocol for canine dental imaging using single‐detector row CT and multidetector row CT. Two medium‐sized mesaticephalic cadaver dog heads were scanned using varying slice thickness, sequential vs. helical scanning mode, sequential CT table increment, pitch, image reconstruction algorithm, and an additional moderate edge enhancement filter. For each series, two reviewers scored dental roots as not visible (score: 0), partially visible (score: 1) or completely visible (score: 2). Sharpness of the dento‐alveolar margin was scored as blurry (score: 0), sharp (score: 1) or very sharp (score: 2). Consensus reader scores were compared among CT protocols. For single‐detector row CT, complete visualization of all tooth roots was only achieved with 1 mm slice thickness and image interval sequential or helical series (pitch of 1 or 2) using a high‐frequency image reconstruction algorithm with or without additional edge enhancement. For four‐detector row CT, complete visibility of all tooth roots was recorded in all series. For single‐detector row CT, all medium frequency algorithm series yielded blurry margin scores and all other series yielded sharp margin scores. For four‐detector row CT, sequential and helical 0.5 mm thickness images yielded very sharp dento‐alveolar margin scores, whereas the 1 mm series yielded only sharp margin scores. Authors concluded that the optimal dental imaging protocol was a sequential mode 1 mm slice thickness and interval with a high‐frequency image reconstruction algorithm and an additional moderate edge enhancement filter.  相似文献   

10.
Computed tomography (CT) is commonly used to assess animals with head trauma. However, strongly attenuating objects such as metallic gunshot cause artifacts that may make accurate localization of shrapnel pieces difficult. The purpose of this study was to develop an optimized CT protocol for minimizing metal artifacts in an animal model of gunshot head trauma. A cadaver head of a stranded Gray seal (Halichoerus grypus) was shot post‐mortem with a 0.223‐inch caliber rifle. The head was frozen, thawed, and scanned using a multislice CT scanner and protocols with varying acquisition and reconstruction parameters. Scans were acquired with and without use of the scanner's proprietary Extended CT Scale (ECTS) mode and beam hardening reduction (Posterior Fossa Optimization [PFO]) filter. Window/level display settings were also varied. For each protocol and each of five selected metallic shrapnel pieces, a single observer measured combined metal halo artifact and shrapnel area using a hand‐traced region of interest. The number of hypo‐ and hyper‐attenuating streak artifacts was also recorded. Measurements were repeated for three different reading sessions. Metal CT artifacts were minimized with a high‐frequency image reconstruction algorithm and a wide window setting. Further artifact reduction was achieved with a proprietary ECTS raw data reconstruction technique and a very wide window. This enabled a more confident evaluation of surrounding bone. On the other hand, these techniques are unfortunately not effective under conditions of soft tissue evaluation. Increasing tube voltage and use of a proprietary PFO filter did not yield a significant reduction in metal artifacts.  相似文献   

11.
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12.
The purpose of this study was to provide an atlas of the normal anatomy of the canine abdomen using helical computed tomographic (CT) images of the abdomen in four mature cross-breed dogs. The dogs were supported in sternal recumbency under general anaesthesia and scans were performed with 5 mm collimation and a pitch of 1. All sections were imaged with soft-tissue window settings and the cranial abdomen was also imaged with mediastinum-vascular window settings. CT scans were performed immediately after iodinated contrast medium was injected into the cephalic vein at 2 mL/kg. Iodinated contrast medium (10 mL/kg) was administered orally 2 h before the scan with a further 3 mL/kg administered immediately prior to scanning. A cross-sectional anatomy atlas was used to identify the structures of the abdominal cavity. Clinically relevant anatomical structures were identified and labelled in the CT images.  相似文献   

13.
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14.
Computed tomography (CT) images of nine dogs with a multilobular tumor of bone of the head were reviewed. The CT characteristics of the neoplasms involving the calvarium (n = 7) were rounded, well defined with a fine granular, nonhomogeneous bone opacity usually in the occipital region. Cranial vault invasion (5 of 7) was commonly found with a significant portion of the mass within the vault. The neoplasms involving the zygomatic arch (n = 2) were also generally rounded and well defined but with a more coarse granular appearance. The common CT findings were best seen when the images were viewed in a bone window.  相似文献   

15.
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.  相似文献   

16.
COMPUTED TOMOGRAPHY OF THE NORMAL FELINE NASAL CAVITY AND PARANASAL SINUSES   总被引：1，自引：0，他引：1  
Computed tomography (CT) images of the feline nasal cavity and paranasal were acquiredfrom noraml adult cats. Good resolutin and amatomic detail were obtained from the CT images using soft tissue formatting. A desciption of normal feline nasal cavity and paranasal sinus anatomy using CT is presented.  相似文献   

17.
The cone-beam type CT (Computed Tomography) enabled us to collect the three-dimensional (3D) digitalized data directly from the animal carcass. In this study, we applied the techniques of the cone-beam type CT for a carcass head of the giant panda (Ailuropoda melanoleuca) to obtain the 3D images easily without reconstruction process, and could morphologically examine the sections from the 3D data by means of non-destructive observations. The important results of the study represent the two following points. 1) We could show the morphological relationships between the muscles of mastication and the mandible in non-destructive status from the 3D data. The exact position of the coronoid process could be recognized in the rostro-lateral space of the temporal fossa. 2) By the serial sections from the 3D data sets, the morphological characteristics in the nasal cavity were detailed with high resolution in this rare species. The nasal concha was well-developed in the nasal cavity. The ethmoidal labyrinth was encountered immediately caudal to the nasal cavity and close to the region of the olfactory bulb. The ethmoidal labyrinth consisted of the complicated osseous structure in this area. The data will be useful to discuss the olfactory function in the reproduction behavior of this species.  相似文献   

18.
Preoperative knowledge of the renal vascular anatomy is important for selection of the appropriate feline renal donor. Intravenous urograms (IVUs) have been performed routinely to screen potential donors at the Veterinary Hospital of the University of Pennsylvania (VHUP), but the vascular phase views lack sufficient detail of the renal vascular anatomy. Computed tomography angiography (CTA), which requires a helical computed tomography (CT) scanner, has been found to provide superior renal vascular anatomic information of prospective human renal donors. The specific aims of this study were as follows: 1) develop the CTA technique for the feline patient; and 2) obtain preliminary information on feline renal vessel anatomy in potential renal donors. Ten healthy, potential feline renal donors were anesthetized and imaged using a third-generation helical CT scanner. The time delay between i.v. contrast medium injection and image acquisition, and other parameters of slice collimation, slice interval, pitch, exposure settings, and reconstruction algorithms were varied to maximize contrast medium opacification of the renal vascular anatomy. Optimal CTA acquisition parameters were determined to be: 1) 10-sec delay post-i.v. bolus of iodinated contrast medium; 2) two serially acquired (corresponding to arterial and venous phases) helical scans through the renal vasculature; 3) pitch of 2 (4 mm/sec patient translation, 2 mm slice collimation); and 4) 120-kVp, 160-mA, and 1-sec exposure settings. Retrospective reconstructed CTA transverse images obtained at a 2-mm slice width and a 1-mm slice interval in combination with two-dimensional reformatted images and three-dimensional reconstructed images were qualitatively evaluated for vascular anatomy; vascular anatomy was confirmed at surgery. Four cats had single renal arteries and veins bilaterally; four cats had double renal veins. One cat had a small accessory artery supplying the caudal pole of the left kidney. One cat had a left renal artery originating from the aorta at a 90 degrees angle with the cranial mesenteric artery. CTA of the feline renal vascular anatomy is feasible, and reconstruction techniques provide excellent anatomic vascular detail. CTA is now used routinely at VHUP to screen all potential feline renal donors.  相似文献   

19.
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20.
The computed tomographic (CT) findings of fungal rhinitis/sinusitis in cats were characterized. The CT images of 10 cats ranging in age from 7 to 13 years were examined. The mean age was 10.8 years and all were neutered males. Nasal aspergillosis was diagnosed in five cats, cryptococcosis in three cats, hyalohyphomycosis in one cat, and trichosporonosis in one cat. Bilateral disease was present in eight cats, seven had abnormal soft tissue attenuation in two-thirds of the nasal cavity, and six had turbinate lysis. Seven cats had also lysis of the hard palate, nasal septum, or frontal bone. One cat had lysis of the cribriform plate. Five of the nine cats whose lymph nodes were imaged had lymph node enlargement. There was contrast medium enhancement in the nasal cavity in all cats, with either a primarily peripheral rim or heterogeneous pattern. There appears to be an overlap of clinical signs, age, and CT features of cats with nasal neoplasia and those with fungal rhinitis/sinusitis.  相似文献   

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