Search Results

Abstract

Case Description—A 3-year-old French Bulldog was evaluated because of acute signs of back pain and spastic paraparesis.

Clinical Findings—Neuroanatomic localization indicated a lesion in the T3-L3 spinal cord segment. Magnetic resonance imaging revealed extradural spinal cord compression at the ventral right aspect of the intervertebral disk space L3–4. On the basis of these findings, a diagnosis of sequestrated Hansen type 1 disk extrusion without extradural hemorrhage was made.

Treatment and Outcome—The dog was treated conservatively with cage rest, restricted exercise on a leash, and NSAIDs. Results of follow-up examination 5 weeks later indicated complete resolution of clinical signs, and results of repeated MRI indicated a 69% reduction in the volume of the herniated disk material.

Clinical Relevance—Findings for the dog of this report indicated spinal cord compression attributable to extruded intervertebral disk material resolved. Functional improvements in dogs with such problems may be partly attributable to spontaneous regression of intervertebral disk extrusions.

Abstract

OBJECTIVE To investigate metabolite concentrations of the brains of dogs with intracranial neoplasia or noninfectious meningoencephalitis by use of short echo time, single voxel proton magnetic resonance spectroscopy (¹H MRS) at 3.0 T.

ANIMALS 29 dogs with intracranial lesions (14 with neoplasia [3 oligodendromas, 3 glioblastomas multiformes, 3 astrocytomas, 2 lymphomas, and 3 meningiomas] and 15 is with noninfectious meningoencephalitis) and 10 healthy control dogs.

PROCEDURES Short echo time, single voxel ¹H-MRS at 3.0 T was performed on neoplastic and noninfectious inflammatory intracranial lesions identified with conventional MRI. Metabolites of interest included N-acetyl aspartate (NAA), total choline, creatine, myoinositol, the glutamine-glutamate complex (Glx), glutathione, taurine, lactate, and lipids. Data were analyzed with postprocessing fitting algorithm software. Metabolite concentrations relative to brain water content were calculated and compared with results for the healthy control dogs, which had been previously evaluated with the same ¹H MRS technique.

RESULTS NAA, creatine, and Glx concentrations were reduced in the brains of dogs with neoplasia and noninfectious meningoencephalitis, whereas choline concentration was increased. Concentrations of these metabolites differed significantly between dogs with neoplasia and dogs with noninfectious meningoencephalitis. Concentrations of NAA, creatine, and Glx were significantly lower in dogs with neoplasia, whereas the concentration of choline was significantly higher in dogs with neoplasia. Lipids were predominantly found in dogs with high-grade intra-axial neoplasia, meningioma, and necrotizing meningoencephalitis. A high concentration of taurine was found in 10 of 15 dogs with noninfectious meningoencephalitis.

CONCLUSIONS AND CLINICAL RELEVANCE ¹H MRS provided additional metabolic information about intracranial neoplasia and noninfectious meningoencephalitis in dogs.

Abstract

OBJECTIVE To describe the perfusion and diffusion characteristics of the liver in healthy dogs as determined by morphological, perfusion-weighted, and diffusion-weighted MRI.

ANIMALS 11 healthy adult Beagles.

PROCEDURES Each dog was anesthetized and underwent morphological, perfusion-weighted, and diffusion-weighted MRI of the cranial aspect of the abdomen. On the MRI images, a region of interest (ROI) was established for each of 6 structures (aorta, caudal vena cava, portal vein, hepatic parenchyma, splenic parenchyma, and skeletal [epaxial] muscle). The signal intensity was determined, and a time-intensity curve was generated for each ROI. The apparent diffusion coefficient (ADC) was calculated for the hepatic and splenic parenchyma in diffusion-weighted MRI images, and the normalized ADC for the liver was calculated as the ratio of the ADC for the hepatic parenchyma to the ADC for the splenic parenchyma. Dogs also underwent abdominal ultrasonography, and ultrasound-guided fine-needle aspirate samples and biopsy specimens were obtained from the liver for cytologic and histologic examination.

RESULTS Cytologic and histologic results suggested that the liver was clinically normal in all dogs. Perfusion-weighted MRI parameters varied among the 6 ROIs. The mean ± SD ADC of the hepatic parenchyma was 0.84 × 10⁻³ mm²/s ± 0.17 × 10⁻³ mm²/s, and the mean normalized ADC for the liver was 1.8 ± 0.4.

CONCLUSIONS AND CLINICAL RELEVANCE Results provided preliminary baseline information about the diffusion and perfusion characteristics of the liver in healthy dogs. Additional studies on dogs of various breeds with and without hepatopathies are necessary to validate and refine these findings.

Abstract

Objective—To characterize the ultrasonographic appearance of the canine esophagus.

Animals—14 healthy Beagles.

Procedures—Endoscopic ultrasonography (EUS) examinations were performed with a radial ultrasonographic gastrovideoscope in anesthetized dogs. Images were obtained at 3-cm intervals along the esophageal length to allow evaluation of the esophageal wall. Images were obtained with the probe in direct contact with the esophageal wall and with a water-filled balloon as a standoff.

Results—Images were obtained with (12 dogs) and without (10) the water-filled balloon. Median thickness of the esophageal wall was 2.19 mm (range, 1.03 to 5.62 mm) in the proximal third of the esophagus, 2.15 mm (range, 1.10 to 4.45 mm) in the middle third, and 2.84 mm (range, 1.35 to 5.92 mm) in the distal third. Wall thickness differed significantly between proximal and distal thirds. Results were similar when the water-filled balloon was used. Esophageal wall layers appeared as 5 alternating hyperechoic and hypoechoic bands that could not be consistently identified in all dogs. All layers could be identified in 26 of 198 (13%) images, 3 layers could be identified in 67 of 198 (34%) images, and 105 of 198 (53%) images had no layers. Visual identification of layers in images obtained with and without the balloon did not differ significantly.

Conclusions and Clinical Relevance—EUS appeared to be a useful technique for assessing esophageal wall integrity in dogs; however, complete evaluation of all layers could not be accomplished in all instances. Further studies with this technique in dogs are needed.

Abstract

OBJECTIVE To investigate regional differences of relative metabolite concentrations in the brain of healthy dogs with short echo time, single voxel proton magnetic resonance spectroscopy (¹H MRS) at 3.0 T.

ANIMALS 10 Beagles.

PROCEDURES Short echo time, single voxel ¹H MRS was performed at the level of the right and left basal ganglia, right and left thalamus, right and left parietal lobes, occipital lobe, and cerebellum. Data were analyzed with an automated fitting method (linear combination model). Metabolite concentrations relative to water content were obtained, including N-acetyl aspartate, total choline, creatine, myoinositol, the sum of glutamine and glutamate (glutamine-glutamate complex), and glutathione. Metabolite ratios with creatine as the reference metabolite were calculated. Concentration differences between right and left hemispheres and sexes were evaluated with a Wilcoxon signed rank test and among various regions of the brain with an independent t test and 1-way ANOVA.

RESULTS No significant differences were detected between sexes and right and left hemispheres. All metabolites, except the glutamine-glutamate complex and glutathione, had regional concentrations that differed significantly. The creatine concentration was highest in the basal ganglia and cerebellum and lowest in the parietal lobes. The N-acetyl aspartate concentration was highest in the parietal lobes and lowest in the cerebellum. Total choline concentration was highest in the basal ganglia and lowest in the occipital lobe.

CONCLUSIONS AND CLINICAL RELEVANCE Metabolite concentrations differed among brain parenchymal regions in healthy dogs. This study may provide reference values for clinical and research studies involving ¹H MRS performed at 3.0 T.

Abstract

Objective—To investigate clinical use of proton magnetic resonance spectroscopy (¹H MRS) and to compare metabolic brain bioprofiles of dogs with and without hepatic encephalopathy.

Animals—6 dogs with hepatic encephalopathy and 12 control dogs.

Procedures—Conventional MRI and single-voxel ¹H MRS were performed with a 3-T magnet. Images for routine MRI planes and sequences were obtained. Single-voxel ¹H MRS was performed with a point-resolved sequence with a short echo time (35 milliseconds) and voxel of interest placement at the level of the basal ganglia. Metabolites of interest included the glutamine-glutamate complex (sum quantification of glutamate and glutamine), myoinositol, N-acetyl aspartate, total choline, and creatine. Data were analyzed with postprocessing fitting algorithm software, and metabolite concentration relative to water and ratios with creatine as the reference metabolite were calculated.

Results—Compared with control dogs, dogs with hepatic encephalopathy had specific changes, which included significantly higher concentration relative to water of the glutamine-glutamate complex and significantly lower concentration of myoinositol. Choline and N-acetyl aspartate concentrations were also slightly lower in dogs with hepatic encephalopathy than in control dogs. No differences in creatine concentration were detected between groups.

Conclusions and Clinical Relevance—¹H MRS aided in the diagnosis of hepatic encephalopathy in dogs, and findings supported the assumption that ammonia is a neurotoxin that manifests via glutamine-glutamate complex derangements. Use of ¹H MRS may provide clinically relevant information in patients with subclinical hepatic encephalopathy, equivocal results of bile acids tests, and equivocal ammonia concentrations or may be helpful in monitoring efficacy of medical management.

Abstract

OBJECTIVE To describe perfusion and diffusion characteristics of the liver, spleen, and kidneys of healthy adult male cats as determined by morphological, perfusion-weighted, and diffusion-weighted MRI.

ANIMALS 12 healthy adult male cats.

PROCEDURES Each cat was anesthetized. Morphological, perfusion-weighted, and diffusion-weighted MRI of the cranial aspect of the abdomen was performed. A region of interest (ROI) was established on MRI images for each of the following structures: liver, spleen, cortex and medulla of both kidneys, and skeletal muscle. Signal intensity was determined, and a time-intensity curve was generated for each ROI. The apparent diffusion coefficient (ADC) was calculated for the hepatic and splenic parenchyma and kidneys on diffusion-weighted MRI images. The normalized ADC for the liver was calculated as the ratio of the ADC for the hepatic parenchyma to the ADC for the splenic parenchyma.

RESULTS Perfusion-weighted MRI variables differed among the 5 ROIs. Median ADC of the hepatic parenchyma was 1.38 × 10⁻³ mm²/s, and mean ± SD normalized ADC for the liver was 1.86 ± 0.18. Median ADC of the renal cortex and renal medulla was 1.65 × 10⁻³ mm²/s and 1.93 × 10⁻³ mm²/s, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE Results provided preliminary baseline information about the diffusion and perfusion characteristics of structures in the cranial aspect of the abdomen of healthy adult male cats. Additional studies of cats of different sex and age groups as well as with and without cranial abdominal pathological conditions are necessary to validate and refine these findings.

Abstract

OBJECTIVE To compare stroke volume (SV) calculated on the basis of cardiac morphology determined by MRI and results of phase-contrast angiography (PCA) of ventricular inflow and outflow in dogs.

ANIMALS 10 healthy Beagles.

PROCEDURES Cardiac MRI was performed twice on each Beagle. Cine gradient echo sequences of both ventricles in short-axis planes were used for morphological quantification of SVs by assessment of myocardial contours. From the long-axis plane, SVs in 4-chamber and left ventricular 2-chamber views were acquired at end diastole and end systole. For calculation of SV on the basis of blood flow, PCA was performed for cardiac valves.

RESULTS Mean ± SD values for SV quantified on the basis of blood flow were similar in all valves (aortic, 17.8 ± 4.1 mL; pulmonary, 17.2 ± 5.4 mL; mitral, 17.2 ± 3.9 mL; and tricuspid, 16.9 ± 5.1 mL). Morphological quantification of SV in the short-axis plane yielded significant differences between left (13.4 ± 2.7 mL) and right (8.6 ± 2.4 mL) sides. Morphological quantification of left ventricular SV in the long-axis plane (15.2 ± 3.3 mL and 20.7 ± 3.8 mL in the 4- and 2-chamber views) yielded variable results, which differed significantly from values for flow-based quantification, except for values for the morphological 4-chamber view and PCA for the atrioventricular valves, for which no significant differences were identified.

CONCLUSIONS AND CLINICAL RELEVANCE In contrast to quantification based on blood flow, calculation on the basis of morphology for the short-axis plane significantly underestimated SV, probably because of through-plane motion and complex right ventricular anatomy.

Abstract

Abstract

OBJECTIVE To characterize delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) features of healthy hyaline cartilage of the distal interphalangeal joint (DIPJ) of horses, to determine whether dGEMRIC can be used to differentiate various stages of naturally occurring osteoarthritis of the DIPJ, and to correlate relaxation times determined by dGEMRIC with the glycosaminoglycan concentration, water content, and macroscopic and histologic findings of hyaline cartilage of DIPJs with and without osteoarthritis.

SAMPLE 1 cadaveric forelimb DIPJ from each of 12 adult warmblood horses.

PROCEDURES T1-weighted cartilage relaxation times were obtained for predetermined sites of the DIPJ before (T1_preGd) and after (T1_postGd) intra-articular gadolinium administration. Corresponding cartilage sites underwent macroscopic, histologic, and immunohistochemical evaluation, and cartilage glycosaminoglycan concentration and water content were determined. Median T1_preGd and T1_postGd were correlated with macroscopic, histologic, and biochemical data. Mixed generalized linear models were created to evaluate the effects of cartilage site, articular surface, and macroscopic and histologic scores on relaxation times.

RESULTS 122 cartilage specimens were analyzed. Median T1_postGd was lower than the median T1_preGd for normal and diseased cartilage. Both T1_preGd and T1_postGd were correlated with macroscopic and histologic scores, whereby T1_preGd increased and T1_postGd decreased as osteoarthritis progressed. There was topographic variation of T1_preGd and T1_postGd within the DIPJ. Cartilage glycosaminoglycan concentration and water content were significantly correlated with T1_preGd and macroscopic and histologic scores but were not correlated with T1_postGd.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dGEMRIC relaxation times varied for DIPJs with various degrees of osteoarthritis. These findings may help facilitate early detection of osteoarthritis.