Objective—To provide a detailed description of cross-sectional anatomic structures of the manus in canine cadavers in association with corresponding features in computed tomographic (CT) and magnetic resonance (MR) images.
Sample Population—7 cadavers of adult large-breed–type dogs (weight range, 25 to 30 kg) without forelimb disease.
Procedures—Forelimbs were removed from the cadavers within 4 hours after euthanasia and frozen. The right forelimbs of 3 cadavers were cut into 4-mm sections by use of a band saw; 1 limb each was sectioned in the transverse, dorsal, or sagittal plane. Sections were cleaned and then photographed. After thawing, transverse CT images of the right forelimbs of 3 additional cadavers were obtained, and the right forelimb of a seventh cadaver underwent MR imaging in the transverse, sagittal, and dorsal planes. The evaluated regions extended from the digits to the carpus. Features in CT and MR images that corresponded to clinically important anatomic structures in tissue sections were identified.
Results—For most of the anatomic structures evident in tissue sections, corresponding CT and MR imaging features were identified. Osseous and musculotendinous structures of the manus were readily detected in CT and MR images, whereas vascular structures were only rarely identified by use of the imaging techniques.
Conclusions and Clinical Relevance—Results of the detailed assessment of anatomic structures of the canine manus in association with corresponding features in CT and MR images will facilitate detection of pathological conditions and be beneficial in planning surgical procedures for diseases of the manus in dogs.
Objective—To characterize the computed tomographic (CT) and cross-sectional anatomic features of myofascial compartments and soft tissue spaces in the manus of cadavers of dogs without forelimb disease.
Animals—33 cadavers of adult medium- to large-breed dogs without forelimb disease.
Procedures—Forelimbs were removed from the cadavers within 4 hours after euthanasia or within 6 hours after thawing from initial freezing. Specimens were then frozen for variable periods and thawed for approximately 16 hours before use. Each manus of 60 forelimbs underwent CT before and after injection of a radiopaque, blue-staining contrast medium into locations where soft tissue spaces and myofascial compartments were predicted (on the basis of pilot study data [6 forelimbs]). Two veterinary radiologists reviewed CT images and recorded the presence or absence of a discrete space or compartment at each injection site. Each manus was subsequently dissected or sectioned transversely. Locations of blue-staining contrast medium accumulation were compared with locations of contrast enhancement in CT images. Anatomic structures within each soft tissue space or myofascial compartment were described.
Results—13 soft tissue spaces and 5 myofascial compartments were identified in the manus. Three myofascial structures that were examined were determined not to be compartments.
Conclusions and Clinical Relevance—Knowledge of soft tissue spaces and myofascial compartments are used to map the likely spread of disease in the hands and feet of humans. Thus, understanding the locations and extent of similar structures in the canine manus may improve the effectiveness of surgical interventions in dogs with injury or inflammation of this region of the forelimb.
To evaluate the enhancement accuracy of a triple-phase abdominal CT angiography (CTA) protocol in dogs and explore the patient, scan, and contrast parameters associated with accuracy of enhancement.
233 client-owned dogs that underwent routine abdominal CTA.
During each CTA study, the subjective timing accuracy (early, ideal, late) of the 3 obtained vascular phases (arterial, venous, delayed) was scored by consensus (2 reviewers) at 4 target organs (liver, pancreas, left kidney, and spleen). These scores were evaluated for statistical associations with 21 study variables (patient, scan, and contrast medium). The objective enhancement (HU) for each target organ was also compared statistically with subjective timing accuracy scores and the study variables.
The study protocol performed best for the pancreas, moderately for the liver, and worse for the spleen and left kidney. Measurements of scan length and time were associated positively with phase lateness for most target organs and phases. Increased heart rate was the most significant patient factor associated positively with phase lateness within the liver (all phases), pancreas (arterial and venous phases), and kidney (arterial phase). Contrast medium variables were less associated with timing accuracy in this protocol. Objective enhancement (HU) correlated poorly with subjective phase timing accuracy and study variables.
Scan time, scan length, and heart rate were the predominant variables contributing to lateness in this canine abdominal CTA protocol. The findings of this exploratory study may aid in protocol adjustment and choice of included anatomy for dogs undergoing routine abdominal CTA.
To evaluate the utility of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values obtained by diffusion-weighted MRI (DWI) at 3.0 T for differentiating intracranial neoplastic lesions from noninfectious inflammatory lesions (NIILs) in dogs.
54 dogs that met inclusion criteria (ie, had a histologically confirmed intracranial lesion and DWI of the brain performed) with 5 lesion types: meningioma [n = 18], glioma , metastatic hemangiosarcoma , other metastatic neoplasms , and NIIL ).
Two observers, who were blinded to the histologic diagnoses, independently determined the mean ADC and FA values for each evaluated intracranial lesion on the basis of 3 circular regions of interest on DWI images. Findings were compared among the 5 lesion types, between all neoplasms combined and NIILs, and between the 5 legion types and previously determined values for corresponding locations for neurologically normal dogs.
The mean ADC and FA values did not differ significantly among the 5 lesion types or between all neoplasms combined and NIILs. However, 35% (14/40) of the neoplastic lesions had an ADC value ≥ 1.443 × 10−3 mm2/s, whereas all NIILs had ADC values < 1.443 × 10−3 mm2/s. Meningiomas and NIILs had FA values that were significantly lower than those for neurologically normal dogs.
CONCLUSIONS AND CLINICAL RELEVANCE
In this population of dogs, the FA values for meningiomas and NIILs differed significantly from those previously reported for neurologically normal dogs. In addition, an ADC cutoff value of 1.443 × 10−3 mm2/s appeared to be highly specific for diagnosing neoplastic lesions (vs NIILs), although the sensitivity and accuracy were low.
OBJECTIVE To acquire MRI diffusion data (apparent diffusion coefficient [ADC] and fractional anisotropy [FA] values, including separate measures for gray and white matter) at 3.0 T for multiple locations of the brain of neurologically normal dogs.
ANIMALS: 13 neurologically normal dogs recruited from a group of patients undergoing tibial plateau leveling osteotomy.
PROCEDURES: MRI duration ranged from 20 to 30 minutes, including obtaining preliminary images to exclude pathological changes (T2-weighted fluid-attenuated inversion recovery transverse and dorsal images) and diffusion-weighted images.,
RESULTS: Globally, there were significant differences between mean values for gray and white matter in the cerebral lobes and cerebellum for ADC (range of means for gray matter, 0.8349 × 10−3 s/mm2 to 0.9273 × 10−3 s/mm2; range of means for white matter, 0.6897 × 10−3 s/mm2 to 0.7332 × 10−3 s/mm2) and FA (range of means for gray matter, 0.1978 to 0.2364; range of means for white matter, 0.5136 to 0.6144). These values also differed among cerebral lobes. In most areas, a positive correlation was detected between ADC values and patient age but not between FA values and patient age.
CONCLUSIONS AND CLINICAL RELEVANCE: Cerebral interlobar and cerebellar diffusion values differed significantly, especially in the gray matter. Information about diffusion values in neurologically normal dogs may be used to diagnose and monitor abnormalities and was the first step in determining the clinical use of diffusion imaging. This information provided an important starting point for the clinical application of diffusion imaging of the canine brain.
Objective—To describe findings of 3.0-T multivoxel proton magnetic resonance spectroscopy (1H-MRS) in dogs with inflammatory and neoplastic intracranial disease and to determine the applicability of 1H-MRS for differentiating between inflammatory and neoplastic lesions and between meningiomas and gliomas.
Animals—33 dogs with intracranial disease (19 neoplastic [10 meningioma, 7 glioma, and 2 other] and 14 inflammatory).
Procedures—3.0-T multivoxel 1H-MRS was performed on neoplastic or inflammatory intracranial lesions identified with conventional MRI. N-acetylaspartate (NAA), choline, and creatine concentrations were obtained retrospectively, and metabolite ratios were calculated. Values were compared for metabolites separately, between lesion categories (neoplastic or inflammatory), and between neoplastic lesion types (meningioma or glioma) by means of discriminant analysis and 1-way ANOVA.
Results—The NAA-to-choline ratio was 82.7% (62/75) accurate for differentiating neoplastic from inflammatory intracranial lesions. Adding the NAA-to-creatine ratio or choline-to-creatine ratio did not affect the accuracy of differentiation. Neoplastic lesions had lower NAA concentrations and higher choline concentrations than inflammatory lesions, resulting in a lower NAA-to-choline ratio, lower NAA-to-creatine ratio, and higher choline-to-creatine ratio for neoplasia relative to inflammation. No significant metabolite differences between meningiomas and gliomas were detected.
Conclusions and Clinical Relevance—1H-MRS was effective for differentiating inflammatory lesions from neoplastic lesions. Metabolite alterations for 1H-MRS in neoplasia and inflammation in dogs were similar to changes described for humans. Use of 1H-MRS provided no additional information for differentiating between meningiomas and gliomas. Proton MRS may be a beneficial adjunct to conventional MRI in patients with high clinical suspicion of inflammatory or neoplastic intracranial lesions.
An 8-year-old 36.3-kg (79.9-lb) spayed female Rottweiler was evaluated because of anorexia and vomiting.
Extrahepatic biliary obstruction (EHBO) secondary to pancreatitis was suspected on the basis of results from serum biochemical analyses, CT, and cytologic examination.
TREATMENT AND OUTCOME
Only marginal improvement was observed after 24 hours of traditional medical management; therefore, novel continual biliary drainage was achieved with ultrasonographically and fluoroscopically guided placement of a percutaneous transhepatic cholecystostomy drainage (PCD) catheter. Within 24 hours after PCD catheter placement, the dog was eating regularly, had increased intestinal peristaltic sounds on abdominal auscultation, no longer required nasogastric tube feeding, and had decreased serum total bilirubin concentration (7.7 mg/dL, compared with 23.1 mg/dL preoperatively). Bile recycling was performed by administering the drained bile back to the patient through a nasogastric tube. The PCD remained in place for 5 weeks and was successfully removed after follow-up cholangiography confirmed bile duct patency.
Transhepatic PCD catheter placement provided fast resolution of EHBO secondary to pancreatitis in the dog of the present report. We believe that this minimally invasive, interventional procedure has the potential to decrease morbidity and death in select patients, compared with traditional surgical options, and that additional research is warranted regarding clinical use, safety, and long-term results of this procedure in veterinary patients, particularly those that have transient causes of EHBO, are too unstable to undergo more invasive biliary diversion techniques, or have biliary diseases that could benefit from palliation alone.
Objective—To determine whether the pattern of extension of modeled infection from the interdigital web spaces in dogs is predictable and whether the distribution differs among initial injury sites.
Sample Population—Thawed frozen forelimbs from 23 cadavers of previously healthy adult medium- to large-breed dogs.
Procedures—The manus of each forelimb was evaluated by use of computed tomography (CT) before and after injection of radiopaque blue-staining contrast medium into the interdigital web spaces. Two veterinary radiologists reviewed the CT images and recorded the extent of contrast medium from each site. Each manus was dissected or sectioned transversely after imaging, and the extent of contrast medium accumulation was recorded and compared with locations of CT contrast enhancement. The Fisher exact test was performed to determine whether the pattern of contrast medium extension differed by injection site.
Results—Injections made in the interdigital web spaces of the canine manus led to unique and predictable patterns of extension into the surrounding soft tissues. That pattern of extension primarily involved the soft tissues of the digits.
Conclusions and Clinical Relevance—In humans, knowledge of common extension patterns from infected soft tissue spaces is used to predict the spread of disease within the hand and develop surgical plans that will minimize patient illness. Identification of the common sites of disease spread from the interdigital web spaces in dogs may help improve surgical planning and treatment for infection in the manus.