ANATOMIC REFERENCE FOR COMPUTED TOMOGRAPHY OF THE HEAD OF THE FOAL

The purpose of this study was to produce an anatomic reference for computed tomography (CT) of the head of the foal for use by radiologists, clinicians, and veterinary students. The head from each of 2 foals, euthanized for reasons unrelated to head pathology, was removed and prepared for CT scanning. Using a third-generation CT scanner, 5-mm contiguous transverse images were acquired. The heads were then frozen and sectioned using a band saw, with the cuts matched as closely as possible to the CT slices. The anatomic sections were photographed and radiographed. The radiographs and anatomic photographs were digitized and matched with the corresponding CT image. Each CT image was compared with its corresponding radiographic and anatomic section to assist in the accurate identification of specific structures. Clinically relevant structures were identified and labeled in corresponding images (CT, anatomic slice, and radiograph of slice). Only structures identified in the CT image were labeled in 1 of the other 2 images. Sagittal (reference) images of the horse's head were reconstructed from the transverse CT scans, and were used to indicate the level from which each of the transverse images was obtained. Corresponding labeled images were then formatted together with a legend for identification of specific anatomic structures.     

The diagnostic yield of conventional radiographs and computed tomography in dogs and cats with maxillofacial trauma

Objective— To compare the diagnostic yield of conventional radiographs and computed tomography (CT) images of the skulls of dogs and cats with maxillofacial trauma (MFT).
Study Design— Prospective study.
Animals— Dogs (n=9) and 15 cats with MFT.
Methods— CT-scans and skull radiographs (4 standard projections) for each animal were evaluated using a semi-quantitative scoring system for the ability to identify 26 predefined, clinically relevant anatomic features (Part 1), and 27 predetermined potential traumatic injuries (Part 2). For Part 1, mean scores for each anatomic feature were recorded for every view and imaging modality. For Part 2, studies were evaluated for the frequency of cases where each predetermined traumatic injury was identified.
Results— Part 1: On radiographs it was easy to identify 17 of 26 anatomic features whereas 6 features were very difficult or impossible to identify on any view. All structures were considered easy or very easy to identify on CT. Scores for CT were lower than radiographs for evaluating dental occlusion and the integrity of the mandibular body. Part 2: CT scans demonstrated 1.6 times more maxillofacial injuries for dogs and 2.0 times more for cats than conventional radiographs. The average number of MFT injuries per animal by radiographs and CT-scan was 4.8 and 7.6 in dogs, and 3.8 and 7.7 in cats, respectively.
Conclusion— CT is superior to conventional skull radiography for identification of anatomic structures and traumatic injuries in dogs and cats. Skull radiography is useful for visualizing the mandibular body and dental occlusion.
Clinical Relevance— CT allows for accurate assessment, diagnosis and treatment planning of MFT in dogs and cats.     

USE OF RADIOGRAPHY IN COMBINATION WITH COMPUTED TOMOGRAPHY FOR THE ASSESSMENT OF NONCARDIAC THORACIC DISEASE IN THE DOG AND CAT

Computed tomography (CT) of the thorax was performed in 28 dogs and five cats and findings were compared with previous thoracic radiographs. The sample population included all animals that had thoracic radiographs and a CT study within 5 days of each other, where the complete imaging studies were available for review. Thoracic radiographs were considered indeterminate in 31 patients and CT examinations were done to acquire additional information. The presence of additional information from CT relating to presence of pathology, location of pathology, extent of pathology, and involvement of mediastinal structures was recorded. Whether there was a change in diagnosis based on the CT findings was also recorded. In only 4/33 animals (all dogs) did CT fail to provide any new information for the parameters evaluated when compared with survey thoracic radiographs. Additional information about the pathology that was present was gained by CT in 5/5 cats and 21/ 28 dogs. New information on compartmental location of pathology was seen in 4/5 cats and 19/28 dogs. New information on pathology extent was noted in 5/5 cats and 20/28 dogs. Additional information regarding involvement of mediastinal structures was obtained in 2/5 cats and 10/28 dogs. A change in diagnosis was made in 3/5 cats and 13/28 dogs. In conclusion, CT is a valuable tool for evaluating intrathoracic disease. CT provides additional cross-sectional anatomic information that can aid in anatomic localization and evaluation of the extent of the pathology in question.     

RADIOGRAPHY AND COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF NONNEOPLASTIC EQUINE MANDIBULAR DISEASE

We compared the information gained from computed tomography (CT) vs. radiography in horses with nonneoplastic disease of the mandible. We hypothesized that CT would provide additional diagnostic information. Medical records, radiographs, and CT images of horses with nonneoplastic mandibular disease evaluated between 1994 and 2008 were reviewed. Nineteen horses were identified; 11 had a tooth root abscess and related disease, four had a fracture of the teeth and/or mandible, and four had a nonneoplastic mass. Both CT images and radiographs allowed identification of diseased teeth that appeared clinically normal otherwise. CT allowed identification of teeth that were clinically affected but appeared normal radiographically. Parameters such as tooth pulp involvement, lamina dura destruction, presence of bone fragments, lingual and buccal mandibular bone periosteal reaction, and cortical bone destruction were more conspicuous with CT. Performing radiography and CT in horses with nonneoplastic mandibular disease provides a more complete evaluation than either technique alone. CT contributes additional information that could otherwise be overlooked with radiographs alone in horses with a mandibular fracture. CT provides ancillary information to radiographs in horses with dental infection or a nonneoplastic mass of the mandible.     

Computed Tomography of the Normal Bovine Tarsus

The objective of this study was to provide a detailed multiplanar computed tomographic (CT) anatomic reference for the bovine tarsus. The tarsal regions from twelve healthy adult cow cadavers were scanned in both soft and bone windows via a 16‐slice multidetector CT scanner. Tarsi were frozen at ?20^o C and sectioned to 10‐mm‐thick slices in transverse, dorsal and sagittal planes respecting the imaging protocol. The frozen sections were cleaned and then photographed. Anatomic structures were identified, labelled and compared with the corresponding CT images. The sagittal plane was indispensable for evaluation of bone contours, the dorsal plane was valuable in examination of the collateral ligaments, and both were beneficial for assessment of the tarsal joint articulations. CT images allowed excellent delineation between the cortex and medulla of bones, and the trabecular structure was clearly depicted. The tarsal soft tissues showed variable shades of grey, and the synovial fluid was the lowest attenuated structure. This study provided full assessment of the clinically relevant anatomic structures of the bovine tarsal joint. This technique may be of value when results from other diagnostic imaging techniques are indecisive. Images presented in this study should serve as a basic CT reference and assist in the interpretation of various bovine tarsal pathology.     

Computed tomographic anatomy of the head of the loggerhead sea turtle (Caretta caretta)

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.     

Computed Tomography and Cross‐sectional Anatomy of the Normal Dromedary Camel Tarsus (One Humped Camel)

The purpose of this study was to provide a detailed computed tomographic (CT) anatomic reference for the dromedary camel tarsus. Six cadaver pelvic limbs, obtained from three clinically and radiographically sound dromedary camels, were scanned in both soft tissue and bone windows starting from the calcaneal tuber towards the proximal metatarsus. Limbs were frozen at ?20°C and sectioned transversely via an electric bone saw. The CT images were evaluated and correlated with their corresponding cryosections. The resulting images provided detailed anatomic features for bones, joints and soft tissue components of the tarsus and are intended to serve as a basic reference for the CT scanning of the dromedary camel tarsal pathology.     

Comparison of thoracic radiographs and single breath-hold helical CT for detection of pulmonary nodules in dogs with metastatic neoplasia

Imaging studies in people indicate that x-ray computed tomography (CT) is a more sensitive technique than thoracic radiography for the detection of pulmonary metastasic neoplasia. Systematic studies comparing CT and thoracic radiographic techniques in veterinary patients have not been performed. The present retrospective study was designed to directly compare the efficacy of these 2 techniques in detecting pulmonary nodules in dogs. Eighteen dogs with histologically confirmed pulmonary metastatic neoplasia had contemporaneous thoracic radiographs and pulmonary CT scans compared. Quantitative analyses included estimation of pulmonary nodule size, number, and lobar distribution on thoracic radiographs and CT images. Only 9% of CT-detected pulmonary nodules were identified on thoracic radiographs (P < .003). The lower size threshold was approximately 1 mm to detect pulmonary nodules on CT images and 7-9 mm to reliably detect nodules on radiographs (P < .0001). Additionally, pulmonary nodules were detected in a significantly greater number of lung lobes using CT as compared with thoracic radiographs (P < .0001). These data indicate that CT is significantly more sensitive than thoracic radiography for detecting soft-tissue nodules in dogs. As such, thoracic CT should be considered in any patient with neoplasia that has potential for pulmonary metastasis to more reliably stage the disease, particularly when accurate characterization of the extent and distribution of pulmonary metastatic disease affects therapeutic planning.     

ANATOMIC ATLAS FOR COMPUTED TOMOGRAPHY IN THE MESATICEPHALIC DOG: HEAD AND NECK

The purpose of this study was to produce a comprehensive anatomic atlas of CT anatomy of the dog for use by veterinary radiologists, clinicians, and surgeons. Whole-body CT images of two mature beagle dogs were made with the dogs supported in sternal recumbency and using a slice thickness of 13 mm. The head was scanned using high-resolution imaging with a slice thickness of 8 mm. At the end of the CT session, each dog was euthanized, and while carefully maintaining the same position, the body was placed in a walk-in freezer until completely frozen. The body was then sectioned at 13-mm (head at 8-mm) intervals, with the cuts matched as closely as possible to the CT slices. The forzen sections were cleaned, photographed, and radiographed using xeroradiography. Each CT image was studied and compared with its corresponding xeroradiograph and anatomic section to assist in the accurate identification of specific structures. Intact, sagittally sectioned, and disarticulated dog skulls were used as reference models. Clinically relevant anatomic structures were identified and labeled in the three corresponding photographs (CT image, xeroradiograph, and anatomic section). In this paper, the CT anatomy of the head and neck of the mesaticephalic dog is presented.     

ANATOMIC ATLAS FOR COMPUTED TOMOGRAPHY IN THE MESATICEPHALIC DOG: CAUDAL ABDOMEN AND PELVIS

The purpose of this study was to produce a comprehensive anatomic atlas of CT anatomy of the dog for use by veterinary radiologists, clinicians, and surgeons. Whole-body CT images of two mature beagle dogs were made with the dogs supported in sternal recumbency and using a slice thickness of 13 mm. At the end of the CT session, each dog was euthanized, and while carefully maintaining the same position, the body was frozen. The body was then sectioned at 13-mm intervals, with the cuts matched as closely as possible to the CT slices. The frozen sections were cleaned, photographed, and radiographed using xeroradiography. Each CT image was studied and compared with its corresponding xeroradiograph and anatomic section to assist in the accurate identification of specific structures. Clinically relevant anatomic structures were identified and labeled in the three corresponding photographs (CT image, xeroradiograph, and anatomic section). In previous papers, the head and neck, and the thorax and cranial abdomen of the mesaticephalic (beagle) dog were presented. In this paper, the caudal part of the abdomen and pelvis of the bitch and male dog are presented.     

ANATOMIC ATLAS FOR COMPUTED TOMOGRAPHY IN THE MESATICEPHALIC DOG: THORAX AND CRANIAL ABDOMEN

The purpose of this study was to produce a comprehensive anatomic atlas of CT anatomy of the dog for use by veterinary radiologists, clinicians, and surgeons. Whole-body CT images of two mature beagle dogs were made with the dogs supported in sternal recumbency and using a slice thickness of 13 mm. At the end of the CT session, each dog was euthanized, and while carefully maintaining the same position, the body was placed in a walk-in freezer until completely frozen. The body was then sectioned at 13-mm intervals, with the cuts matched as closely as possible to the CT slices. The frozen sections were cleaned, photographed, and radiographed using xeroradiography. Each CT image was studied and compared with its corresponding xeroradiograph and anatomic section to assist in the accurate identification of specific structures. Clinically relevant anatomic structures were identified and labeled in the three corresponding photographs (CT image, xeroradiograph, and anatomic section). In a previous paper, the head and neck of the mesaticephalic (beagle) dog was presented. In this paper, the thorax and cranial part of the abdomen of the dog are presented.     

Computed tomographic findings of the gastrointestinal tract in rabbits

BackgroundGastrointestinal (GI) diseases are common in rabbits. Although diagnostic imaging studies can assist clinicians in selecting therapeutic approaches, there are few reports of advanced imaging findings in normal rabbits. Computed tomography (CT) is recognized as a useful tool in dogs and cats, but there are few reports of normal findings on multidetector computed tomography (MDTC) in rabbits. The goals of this study are to describe the CT anatomic imaging appearance of the GI tract and their normal variation in healthy pet rabbits and to obtain the normal wall thickness measurements of normal GI tract structures.MethodsTwenty-three rabbits were scanned under general anesthesia and the CT abdominal images were analyzed by two experienced radiologists. Location and size of the major GI organs and structures were determined, and wall thickness of the stomach, small and large intestines were measured, including the interobserver agreement. Statistical analysis of quantitative and qualitative variables was performed.ResultsWall thickness values were established for the different parts of the stomach (cardia: 3.4 ± 0.4mm; fundus: 1.4 ± 0.2mm; body: 1.4 ± 0.1mm; pylorus: 2.9 ± 0.5mm), small intestines (duodenum: 1.4 ± 0.1mm; jejunum: 1.2 ± 0.1mm; ileum: 1.4 ± 0.1mm), and large intestines (cecum: 1.2 ± 0.1mm; colon ascending: 1.4 ± 0.3 mm and descending: 1.3 ± 0.3mm). When distended the stomach did not extend beyond the caudal limits of the L2 vertebra. The cecum occupied the ventral abdominal region from T12/T13 to L7/S1, the sacculus rotundus was identified in 11 of the 23 rabbits. The sacculus rotundus and vermiform cecal appendix were identified only in rabbits with mild large intestinal distension.Conclusions and clinical relevanceIt was possible to use CT to evaluate the different portions of the GI tract that are not normally readily visible on radiographs and ultrasound (US). Normal wall thickness values of the different portion of the GI tract were stablished. These results provide new and important reference values for CT studies in normal pet rabbits and provide data for further studies in rabbits with GI diseases.     

Cerebral cysticercosis in pigs studied by computed tomography and necropsy

An original technique for computed tomography (CT) of the pig's brain is described. Brains of 11 cysticercotic pigs were studied by CT and by macroscopic and microscopic examination after necropsy, in order to compare the tomographic images with the anatomic findings. By CT, cysticerci could be seen in all the brains except one which had only one parasite. Good correlation was found when the CT sections were compared with the anatomic slices, nevertheless not all cysticerci seen during necropsy examination could be identified in the CT images. Only two parasites were found in the ventricles. There were difficulties in differentiating submeningeal and parenchymal localization of the cysticerci. Most cysticerci had similar morphologic appearance; inflammatory reactions of different degrees and characteristics were observed around some of them.     

RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC DETERMINATION OF FEMORAL VARUS AND TORSION IN THE DOG

Diagnosis and quantification of femoral varus and femoral torsion using radiographs is technically challenging due to the difficulty in determining proper positioning. The purpose of this study is to describe a computed tomographic technique for determination of femoral varus and femoral torsion and to compare this technique, and standard radiography, to anatomic preparation, for the measurement of femoral varus and femoral torsion in normal dogs. Nine canine cadavers, visually and radiographically free of orthopedic disease of the hip and stifle joints, were utilized for analysis. Femoral varus was determined using a craniocaudal radiograph, a craniocaudal radiograph obtained after confirming accurate positioning using horizontal beam fluoroscopy, and computed tomography (CT). Femoral torsion (expressed as angle of version) was determined using an axial radiographic projection obtained from distal to proximal and CT. Each femur was dissected free of soft tissues, and direct determination of femoral varus and femoral torsion was performed using digital photographic images. All radiologic and photographic images were digitally measured to quantify the magnitude of femoral varus and femoral torsion. For femoral varus, no difference ( P =0.149) between the three different imaging techniques and the anatomic preparation was identified. For femoral torsion, no difference ( P =0.059) between the two imaging techniques and the anatomic preparation was identified. Well positioned radiographs and the described computed tomographic method are both as accurate as anatomic preparation for the measurement of both femoral varus and femoral torsion in normal dogs.