Multiple liver abscesses in a dog secondary to the liver fluke Metorchis conjunctus treated by percutaneous transhepatic drainage and alcoholization.

A 1-year-old German shepherd × husky cross dog was diagnosed with multiple liver abscesses and severe cholangitis secondary to the liver fluke Metorchis conjunctus. The dog was successfully treated with 2 percutaneous transhepatic drainage and alcoholization procedures, and a prolonged course of antibiotics and praziquantel.

Abcès hépatiques multiples chez un chien secondaire à une douve du foieMetorchis conjunctustraitée par drainage transhépatique percutané et alcoolisation. Un chien de race croisée Berger allemand et Husky âgé de 1 an a été diagnostiqué avec des abcès hépatiques multiples et une cholangite grave secondaire à la douve du foie Metorchis conjunctus. Le chien a été traité avec succès à l'aide de deux interventions de drainage transhépatique percutané et d'alcoolisation ainsi que d'un traitement prolongé aux antibiotiques et au praziquantel.(Traduit par Isabelle Vallières).

Invited review--Off-site PET imaging programs: challenges and opportunities.

Veterinarians are gaining interest in and access to Position Emission Tomography (PET and PET/CT) imaging for both clinical and research applications. This manuscript provides an overview of how veterinarians may approach the use of off-site PET and PET/CT scanners already in use for human medical imaging in order to gain access to this technology without direct investment in costly equipment and infrastructure. An overview of general procedures, animal transport, and radiation safety considerations is offered along with references to key regulatory statutes that may apply to the operation of PET imaging facilities in individual states.

Computed tomography radiomic features hold prognostic utility for canine lung tumors: An analytical study.

Quantitative analysis of computed tomography (CT) radiomic features is an indirect measure of tumor heterogeneity, which has been associated with prognosis in human lung carcinoma. Canine lung tumors share similar features to human lung tumors and serve as a model in which to investigate the utility of radiomic features in differentiating tumor type and prognostication. The purpose of this study was to correlate first-order radiomic features from canine pulmonary tumors to histopathologic characteristics and outcome. Disease-free survival, overall survival time and tumor-specific survival were calculated as days from the date of CT scan. Sixty-seven tumors from 65 dogs were evaluated. Fifty-six tumors were classified as primary pulmonary adenocarcinomas and 11 were non-adenocarcinomas. All dogs were treated with surgical resection; 14 dogs received adjuvant chemotherapy. Second opinion histopathology in 63 tumors confirmed the histologic diagnosis in all dogs and further characterized 53 adenocarcinomas. The median overall survival time was longer (p = 0.004) for adenocarcinomas (339d) compared to non-adenocarcinomas (55d). There was wide variation in first-order radiomic statistics across tumors. Mean Hounsfield units (HU) ratio (p = 0.042) and median mean HU ratio (p = 0.042) were higher in adenocarcinomas than in non-adenocarcinomas. For dogs with adenocarcinoma, completeness of excision was associated with overall survival (p<0.001) while higher mitotic index (p = 0.007) and histologic score (p = 0.037) were associated with shorter disease-free survival. CT-derived tumor variables prognostic for outcome included volume, maximum axial diameter, and four radiomic features: integral total, integral total mean ratio, total HU, and max mean HU ratio. Tumor volume was also significantly associated with tumor invasion (p = 0.044). Further study of radiomic features in canine lung tumors is warranted as a method to non-invasively interrogate CT images for potential predictive and prognostic utility.

Diagnosis, management, and outcome in 19 horses with deltoid tuberosity fractures.

OBJECTIVE: To describe the diagnosis and treatment of fractures of the deltoid tuberosity. STUDY DESIGN: Case series. METHODS: Medical records (1992-2009) of 19 horses with radiographic confirmation of deltoid tuberosity fractures were reviewed. Data retrieved included signalment, clinical and diagnostic imaging findings, and treatment. Outcome was determined by telephone questionnaire of owners and referring veterinarians. RESULTS: Most horses were markedly lame on admission and 53% had reduced protraction of the affected limb. All fractures were identified on a cranio45° medial-caudolateral oblique projection; however, only 32% (6 horses) were detected on a mediolateral projection whereas 86% were evident ultrasonographically. Treatment by local wound care and stall rest resulted in return to athletic function without lameness for 13 of 14 horses that had follow-up. CONCLUSIONS: A cranio45° medial-caudolateral oblique radiographic view was better than a mediolateral projection for identification of deltoid tuberosity fractures. Ultrasonographic detection of fractures was similar except when gas accumulation obscured the fracture site. Deltoid tuberosity fractures can cause severe lameness but can be treated successfully with conservative management.

Three-dimensional imaging of whole rodent organs using optical computed and emission tomography.

We explore the potential of optical computed tomography (optical-CT) and optical emission computed tomography (optical-ECT) in a new area-whole organ imaging. The techniques are implemented on an in-house prototype benchtop system with improved image quality and the capacity to image larger samples (up to 3 cm) than previous systems based on stereo microscopes. Imaging performance tests confirm high geometrical accuracy, accurate relative measurement of linear attenuation coefficients, and the ability to image features at the 50-microm level. Optical labeling of organ microvasculature was achieved using two stains deposited via natural in vivo circulatory processes: a passive absorbing ink-based stain and an active fluorescin FITC-lectin conjugate. The lectin protein binds to the endothelial lining, and FITC fluorescense enables optical-ECT imaging. Three-dimensional (3-D) optical-CT images have been acquired of a normal rat heart and left lung and a mouse right lung showing exquisite detail of the functional vasculature and relative perfusion distribution. Coregistered optical-ECT images were also acquired of the mouse lung and kidney. Histological sections confirmed effective labeling of microvasculature throughout the organs. The advantages of optical-CT and optical-ECT include the potential for a unique combination of high resolution and high contrast and compatibility with a wide variety of optical probes, including gene expression labeling fluorescent reporter proteins.

The use of multi-detector row computed tomography (MDCT) as an alternative to specimen preparation for anatomical instruction.

The purpose of the study reported here was to establish a method of teaching veterinary anatomy, including radiologic anatomy, for clinical practice using computer-aided diagnosis (CAD). Two clinically healthy dogs and three cats were scanned using multi-detector row computed tomography (MDCT). Images were made by means of imaging processing software. At the workstation, by observing the transverse, dorsal-plane, or sagittal sections and three-dimensional (3D) images simultaneously, it is much easier to understand the 3D anatomical structure. With this educational support system, anatomical figures can be explained using living animals instead of specimens. In addition, clinical representative examples can be used to show anatomical disorders to students. Veterinary students (N = 62) who filled out a questionnaire evaluating how the method aided their understanding of both experimental study and clinical examples gave it a score of 88.2 +/- 20.6 (Mean +/- SD) on a visual analog scale. This system can enhance veterinary students' understanding and interest in anatomy and can enable us to offer them a quality veterinary medical education. We concluded that CAD is a useful new option not only for clinical service but also for veterinary education.

High-resolution PET in cats: application of a clinical camera to experimental studies.

UNLABELLED: A commercial high-resolution scanner designed for clinical PET studies was tested for its applicability to investigate cerebral metabolism and blood flow in cats. METHODS: Cerebral blood flow, CMRO2, CBV and CMRglc were determined repeatedly using 15O steady-state oxygen methods and 18F-fluorodeoxyglucose (FDG). Metabolic and blood flow images of 14 contiguous 3-mm PET slices were compared to histological sections in four control animals. In another six cats, hemodynamic and metabolic changes were followed by serial multi-tracer PET for 24 hr after permanent occlusion of the left middle cerebral artery (MCA). Pattern and extent of changes of the physiological variables were related to the final infarct verified in matched histological sections. RESULTS: At spatial resolutions (FWHM) of 3.6 mm in transaxial planes and 4.0 mm axially, details of the gross anatomy of the cat brain were distinguished best in the FDG images. Cerebral blood flow, CMRO2 and CMRglc values measured in the cortex, white matter and basal ganglia were in the range of common autoradiographic results. Immediately after MCA occlusion, there was widespread decrease in blood flow, but metabolism was preserved at values, which suggest viable tissue. With time, the areas of increased oxygen extraction fraction (OEF) moved from the center to the periphery of the MCA territory. CONCLUSION: High-resolution PET can be used for repeat, quantitative imaging of blood flow and metabolism in small animals such as the cat. After MCA occlusion, the changes in blood flow and metabolism can be followed over time and can be related to the final morphological lesion.

PET imaging of osteosarcoma in dogs using a fluorine-18-labeled monoclonal antibody Fab fragment.

UNLABELLED: Four dogs with histologically confirmed osteogenic sarcoma were studied with PET following intravenous injection of the 18F-labeled Fab fragment of TP-3, a monoclonal antibody specific for human and canine osteosarcomas. METHODS: The antibody fragment was labeled using the N-succinimidyl 8-[(4'-[18F]fluorobenzyl)amino]suberate acylation agent. Blood clearance of activity was biphasic in all dogs but half-times were variable (T1/2 beta = 2-13 hr). Catabolism of labeled Fab was reflected by the decrease in protein-associated activity in serum from more than 90% at 1 min to 60%-80% at 4 hr. RESULTS: PET images demonstrated increased accumulation of 18F at the primary tumor site relative to normal contralateral bone in one dog as early as 15 min after injection. Biopsies obtained after euthanasia indicated higher uptake at the edges of the tumor as observed on the PET scans. Tumor uptake was 1-3 x 10(-3)% injected dose/g, a level similar to that reported for other Fab fragments in human tumors. In the three dogs with metastatic disease, early PET images reflected activity in the blood pool but later uptake was observed in suspected metastatic sites. CONCLUSIONS: These results, although preliminary, suggest that PET imaging of 18F-labeled antibody fragments is feasible and that dogs with spontaneous tumors could be a valuable model for preclinical research with radioimmunoconjugates.

Imaging small animals with positron emission tomography.

During the past few years many research centers have successfully applied their knowledge of positron emission tomography (PET) to construct PET scanners which are dedicated to image small animals such as rats and mice. Although there are many in-house built systems which are used in laboratory environments, only a few of them are commercially available at this time. This review will give an overview of dedicated animal PET systems with their technical description and main physical characteristics. Graphical analysis of spatial resolution against absolute sensitivity allows a comparison of the most important characteristics of each camera. The quadHIDAC, a PET scanner recently installed at the Department of Nuclear Medicine, University Hospital Münster, acquires images with sub-millimeter spatial resolution. A (18)F-FDG whole body image of a mouse with small structures like the left ventricle of the heart clearly visualized, demonstrates its excellent spatial resolution.

Performance stability of SHR-2000 high resolution PET for animal research.

The performance of a high resolution positron emission tomography (PET) system SHR-2000 for animal studies was re-evaluated six years after its installation. The system employs a detector array consisting of BGO crystals that are 1.7 mm (transaxially) by 10 mm (axially) by 30 mm (deep). A block detector, which is a position-sensitive photomultiplier tube (PMT) coupled to 4 arrays of BGO crystals has been adopted to the system. There are 15 block detectors positioned to form a 35 cm diameter ring with a field of view (FOV) of 17 cm by 4.6 cm axially, giving the system a 7 slice imaging capability. For six year workload in spatial resolution (FWHM), there were approximately a 2.6% increase at tangential FOV and a 7.5% increase at radial FOV. In axial resolution (FWHM) there was almost no change. The count rate loss for the true count rate increased 1.3% at 200 kBq/ ml. The average slice sensitivity showed a decrease of approximately 4.1%, and in scatters it showed an increase of approximately 1.4%. In animal experiments, the bones of guinea pigs were clearly identified with 18F fluoride ion. These experiments show that after a six year workload, the system also maintains good performance and has good stability.

New and future advanced imaging techniques.

The advances in diagnostic imaging in the past 20 years have been nothing short of phenomenal. This article presents what is available with some of the latest in state-of-the-art techniques. Included are three-dimensional techniques, vascular MRI, high-resolution three-dimensional video animation, positron emission tomography, MR spectroscopy, and other developing methodology in diagnostic imaging.

Surgical treatments for seizure. Adaptability for dogs.

Surgical treatments are often used for human epileptics who are refractory to more conventional anticonvulsant therapies. The goals of surgery are to decrease seizure morbidity or, ideally, bring about a cure to the seizure disorder. As a sizable subpopulation of dogs with seizures are also refractory to currently available anticonvulsant therapies, consideration has been given to evaluating alternative treatments for seizures in dogs. This article discusses the adaptability of surgical treatments used in humans for use in seizure control in affected dogs.

Hansen type I disk disease at T1-2 in a dachshund.

A 7-year-old Dachshund was presented with chronic left thoracic limb lameness and acute neurological deficits to the hind limbs following trauma. A lesion was suspected between C7 and T2 on the basis of neurological examinations. Radiography and myelography identified a calcified intervertebral disk at C7-T1 and an extradural unilateral compressive lesion at T1-2. Computed tomography scans of the cranial thoracic spine revealed extrusion of disk material from the T1-2 intervertebral space resulting in marked spinal cord compression. Intervertebral disk disease is rarely reported at this location. The neurological condition deteriorated after a second myelogram, which was done to examine the thoracolumbar spine. A modified dorsal decompression of T1-2 was performed. The dog was euthanased due to further neurological deterioration 8 days after surgery.

Future directions in small animal imaging.

The adaptation and development of imaging technologies for use in small animals has the potential to be a refinement with profound effects on how basic cancer research using animals is conducted. The authors describe how NCI funding is helping to advance research in this area.

A review of high-resolution X-ray computed tomography and other imaging modalities for small animal research.

Dedicated high-resolution small animal systems have recently emerged as important new tools for laboratory animal research. These imaging systems permit researchers to noninvasively screen animal models for mutations or pathologies and to monitor disease progression and response to therapy. The authors survey various small animal imaging modalities, including MRI, PET, SPECT, and microCT, and discuss several representative microCT mouse imaging studies.

[Positron emission tomography: diagnostic imaging on a molecular level]. / Positronen-Emissions-Tomographie: Ein bildgebendes Verfahren auf molekularer Ebene.

In human medicine positron emission tomography (PET) is a modern diagnostic imaging method. In the present paper we outline the physical principles of PET and give an overview over the main clinic fields where PET is being used, such as neurology, cardiology and oncology. Moreover, we present a current project in veterinary medicine (in collaboration with the Paul Scherrer Institute and the University Hospital Zurich), where a hypoxia tracer is applied to dogs and cats suffering from spontaneous tumors. Finally new developments in the field of PET were discussed.

A craniopharyngioma in a seven-year-old dog.

A seven-year-old male Border Collie was presented with a history of lethargy, episodic circling, incoordination and polydypsia. Physical examination revealed depression, obesity and bradycardia. A neurological examination indicated the possible presence of a space-occupying lesion in the brain. Results of the clinical investigation revealed hyposthenuria, sinus bradycardia and increased concentration of protein in the cerebrospinal fluid. A computerised axial tomography scan revealed a mass in the region of the hypophysis. The dog was euthanased and a post mortem examination confirmed the presence of a craniopharyngioma.

Accurate modeling of a DOI capable small animal PET scanner using GATE.

In this work we developed a Monte Carlo (MC) model of the Sedecal Argus pre-clinical PET scanner, using GATE (Geant4 Application for Tomographic Emission). This is a dual-ring scanner which features DOI compensation by means of two layers of detector crystals (LYSO and GSO). Geometry of detectors and sources, pulses readout and selection of coincidence events were modeled with GATE, while a separate code was developed in order to emulate the processing of digitized data (for example, customized time windows and data flow saturation), the final binning of the lines of response and to reproduce the data output format of the scanner's acquisition software. Validation of the model was performed by modeling several phantoms used in experimental measurements, in order to compare the results of the simulations. Spatial resolution, sensitivity, scatter fraction, count rates and NECR were tested. Moreover, the NEMA NU-4 phantom was modeled in order to check for the image quality yielded by the model. Noise, contrast of cold and hot regions and recovery coefficient were calculated and compared using images of the NEMA phantom acquired with our scanner. The energy spectrum of coincidence events due to the small amount of (176)Lu in LYSO crystals, which was suitably included in our model, was also compared with experimental measurements. Spatial resolution, sensitivity and scatter fraction showed an agreement within 7%. Comparison of the count rates curves resulted satisfactory, being the values within the uncertainties, in the range of activities practically used in research scans. Analysis of the NEMA phantom images also showed a good agreement between simulated and acquired data, within 9% for all the tested parameters. This work shows that basic MC modeling of this kind of system is possible using GATE as a base platform; extension through suitably written customized code allows for an adequate level of accuracy in the results. Our careful validation against experimental data confirms that the developed simulation setup is a useful tool for a wide range of research applications.

Radiopharmaceutical pharmacokinetics in animals: critical considerations.

Since the advent of single photon emission computerized tomography (SPECT) and positron emission tomography (PET) various chemical ligands have been labeled with radionuclides and evaluated as tracer compounds in animal models to ascertain their suitability as potential radiopharmaceuticals for humans. In the absence of a defined algorithm to predict the diagnostic efficacy of a radiopharmaceutical, any new radioligand has to undergo preclinical evaluation even if it has excellent in vitro properties. Until now few studies have produced pharmacokinetic data that could be translated from animal models directly to humans. The purpose of this review is to highlight some critical aspects to consider during the development and validation phase of a new radiopharmaceutical. Interspecies differences and the absence of knowledge of physiological mechanism can become challenging drawbacks for obtaining a successful radiopharmaceutical. In this context, the influence of ABC transporters in neuroimaging, the effect of plasma protein binding and the consequence of anesthesia with reference to interspecies differences will be discussed with illustrative examples.