OBJECTIVE To determine whether dual-energy CT (DECT) could accurately differentiate the composition of common canine uroliths in a phantom model.
SAMPLE 30 canine uroliths with pure compositions.
PROCEDURES Each urolith was composed of ≥ 70% struvite (n = 10), urate (8), cystine (5), calcium oxalate (4), or brushite (3) as determined by standard laboratory methods performed at the Canadian Veterinary Urolith Centre. Uroliths were suspended in an agar phantom, and DECT was performed at low (80 kV) and high (140 kV) energies. The ability of low- and high-energy CT numbers, DECT number, and DECT ratio to distinguish uroliths on the basis of composition was assessed with multivariate ANOVA.
RESULTS No single DECT measure differentiated all urolith types. The DECT ratio differentiated urate uroliths from all other types of uroliths. The DECT and low-energy CT numbers were able to differentiate between 8 and 7 pairs of urolith types, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that DECT was unable to differentiate common types of canine uroliths in an in vitro model; therefore, it is unlikely to be clinically useful for determining urolith composition in vivo. Given that the primary reasons for determining urolith composition in vivo are to predict response to shock wave lithotripsy and develop a treatment plan, future research should focus on the correlation between DECT measurements and urolith fragility rather than urolith composition.
A 4.5-year-old 15.8-kg (34.8-lb) sexually intact female clouded leopard (Neofelis nebulosa) from a zoological collection was anesthetized for routine examination and melengestrol acetate (MGA) contraceptive implant removal in preparation for breeding. The MGA implant (48.1 mg/kg [21.86 mg/lb], SC) had been surgically placed 20 months prior to this examination and 8 months following the delivery of 2 healthy cubs. Findings on physical examination were unremarkable except for a firm, prominent, tubular structure in the caudal aspect of the abdomen that was detected on palpation. Findings on CBC, serum biochemical analysis, and urinalysis were within acceptable limits. Radiographs
A 3-year-old neutered male Cocker Spaniel was evaluated because of a 1-day history of trembling and dyspnea. The dog also had a 3-month history of once-weekly retching and vomiting after eating a large amount of food. On physical examination, the dog was tachypneic and dyspneic. Thoracic auscultation revealed vesicular lung sounds on the left and diminished lung sounds on the right. Heart sounds were muffled on the right. No murmur was auscultated. Abnormalities on CBC included mild anemia and mild leukocytosis, characterized by neutrophilia, monocytosis, and basophilia. Serum biochemical analysis revealed mildly low urea and chloride concentrations. Thoracic radiographs
A 4-month-old sexually intact male Great Dane was referred because of regurgitation since being acquired at 3 months of age. The frequency of regurgitation had historically been approximately 3 to 4 episodes/d but had increased dramatically over the 24 hours prior to referral, with 20 to 30 episodes of regurgitation and 1 episode of vomiting being reported. The regurgitated material was described as containing food, liquid, and foam, and episodes were not related to feedings. The dog's appetite had always been good; however, the owners reported that the dog had been anorectic the morning of initial evaluation. Vaccination and
Objective—To assess whether the risk of development
of hypothyroidism after treatment with iodine
131 (131I) was associated with the pattern of sodium
pertechnetate Tc 99m activity in the thyroid gland
detected via scintigraphy before treatment in cats
Procedure—Medical records of cats with hyperthyroidism
that had been treated with 131I (from 1990 to
2002) and had undergone scintigraphy of the thyroid
gland before treatment were reviewed; data regarding
signalment, scintigraphic findings (classified as
unilateral, bilateral-asymmetric, bilateral-symmetric,
or multifocal patterns), serum total thyroxine (T4) concentrations
before treatment and prior to hospital discharge,
and 131I treatment were collected. A questionnaire
was sent to each referring veterinarian to obtain
additional data including whether the cats subsequently
developed hypothyroidism (defined as serum
total T4 concentration less than the lower reference
limit ≥ 3 months after treatment).
Results—50 of 165 (30.3%) 131I-treated cats developed
hypothyroidism. Hypothyroidism developed in 39
of 109 cats with bilateral, 10 of 50 cats with unilateral,
and 1 of 6 cats with multifocal scintigraphic patterns of
their thyroid glands. Cats with a bilateral scintigraphic
pattern were approximately 2 times as likely to develop
hypothyroidism after 131I treatment than were cats
with a unilateral scintigraphic pattern (hazard ratio, 2.1;
95% confidence interval, 1.04 to 4.2).
Conclusions and Clinical Relevance—Cats with
hyperthyroidism that have a bilateral scintigraphic pattern
in the thyroid gland before 131I treatment appear to
have a significantly higher risk of subsequently developing
hypothyroidism, compared with cats with a unilateral
scintigraphic pattern. (J Am Vet Med Assoc
OBJECTIVE To determine, by means of MRI, the time to maximal contrast enhancement in T1-weighted images following IV administration of gadoxetic acid in healthy dogs and assess the impact of gadoxetic acid on the signal intensity of T2-weighted images.
ANIMALS 7 healthy dogs.
PROCEDURES No hepatic abnormalities were detected during ultrasonographic examination. Each dog was anesthetized and positioned in dorsal recumbency for MRI. Transverse T1- and T2-weighted images of the liver were acquired prior to and following (at 5-minute intervals) IV injection of 0.1 mL of gadoxetic acid/kg. Signal intensity of the liver parenchyma was measured in 3 regions of interest in the T1- and T2-weighted images before and at various times point after contrast agent administration. Time versus signal-to-noise ratio curves were plotted to determine time to maximal contrast enhancement and contrast agent–related changes in signal intensity in T2-weighted images.
RESULTS Analysis of T1-weighted images revealed that mean ± SD time to maximal enhancement after gadoxetic acid injection was 10.5 ± 3.99 minutes. Signal intensity of T2-weighted images was not significantly affected by gadoxetic acid administration. No injection-related adverse effects were observed in any dog.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that gadoxetic acid can be used for hepatic MRI in healthy dogs and the resultant hepatic enhancement patterns are similar to those described for humans. Maximal contrast enhancement occurred between 10 and 15 minutes after contrast agent injection; thus, T2-weighted images may be obtained in the interval between injection and maximal enhancement for a more time-efficient clinical protocol.
Objective—To evaluate the efficacy and effects of labeling equine umbilical cord blood (UCB)– and bone marrow (BM)–derived multipotent mesenchymal stromal cells (MSCs) with an ultrasmall superparamagnetic iron oxide (SPIO) contrast agent and the detection of labeled MSCs by use of MRI.
Sample—UCB MSCs from placental tissues of 5 foals and BM MSCs from 5 horses.
Procedures—UCB and BM MSC cultures were seeded in duplicate (5,000 cells/cm2). One duplicate was incubated with SPIO (50 μg/mL); the other was processed identically, but without SPIO. Mesenchymal stromal cells were expanded in triplicates for 5 passages and assessed for viability and proliferative capacity, labeling efficacy, and labeled cell proportion. For MRI detection, 5 × 106 labeled BM MSCs from passage 1 or 2 were injected into a collagenase-induced superficial digital flexor tendon defect of an equine cadaveric forelimb from 2 horses.
Results—For passages 1, 2, and 3, labeling efficacy and cell proportion for UCB MSCs (99.6% [range, 98.8% to 99.9%], 16.6% [range, 6.5% to 36.1%], and 1.0% [range, 0.4% to 2.8%], respectively) were significantly higher than for BM MSCs (99.2% [range, 97.8% to 99.7%], 4.5% [range, 1.6% to 11.8%], and 0.2% [range, 0.1% to 0.6%], respectively). Labeling was not detectable after passage 3. Viability of MSCs was not affected, but cell doubling time increased in labeled MSCs, compared with that of unlabeled MSCs. On MRI 3-D T2*-weighted fast gradient echo sequences, decreased signal intensity was observed for BM passage 1 MSCs.
Conclusions and Clinical Relevance—Equine UCB and BM MSCs were labeled with SPIO at high efficiencies.
Objective—To determine whether the ventrodorsal myelographic view can be used to accurately predict the circumferential location of extruded disk material in dogs with thoracolumbar intervertebral disk extrusion (IVDE) and to describe paradoxical contrast obstruction (PCO).
Design—Retrospective case series.
Animals—104 dogs with Hansen type I IVDE.
Procedures—Ventrodorsal myelographic views were reviewed, and contrast patterns were categorized according to 8 predetermined patterns. Agreement among observers was compared, and the predicted location of extruded disk material was compared with surgical findings.
Results—Agreement regarding myelographic pattern and location of extruded disk material was moderate (κ = 0.74 and 0.80, respectively) among the 4 observers. Ninety-three (89%) dogs had myelographic evidence of lateralized extrusion, and in 83 of the 93 (89%), predicted location of extruded disk material matched the surgically confirmed location. In 33 of the 40 (83%) dogs with bilateral contrast column gaps of unequal length, disk material was found to be located on the side with the shorter, rather than the longer, contrast gap, a phenomenon described as PCO.
Conclusions and Clinical Relevance—Results suggested that the ventrodorsal myelographic view could be used to predict the circumferential location of extruded disk material in dogs with thoracolumbar IVDE more often than previously reported. The PCO phenomenon may be useful in determining the side of lateralization when contrast material does not outline the extruded disk material.
OBJECTIVE To determine effects of repeated use and resterilization on structural and functional integrity of microwave ablation (MWA) antennas.
SAMPLE 17 cooled-shaft MWA antennas (3 groups of 5 antennas/group and 2 control antennas).
PROCEDURES 1, 2, and 3 ablations in the livers of bovine cadavers were performed at the maximum recommended settings. Antennas were cleaned and sterilized in hydrogen peroxide plasma, and the process was repeated (reprocessing cycle; n = 6). Control antennas were only sterilized (6 times). Aerobic and anaerobic bacterial cultures were performed, and antennas were microscopically assessed for damage.
RESULTS 6 cycles were completed. Thirteen of 15 MWA antennas remained functional for up to 4 cycles, 10 were functional after 5 cycles, and only 7 were functional after 6 cycles. Progressive tearing of the silicone coating of the antennas was observed, with a negative effect of the number of cycles for silicone tearing. Size of the ablation zone decreased mildly over time after cycles 5 and 6; however, this was not considered clinically relevant. No significant changes in the shape of ablation zones were detected. All cultures yielded negative results, except for an isolated case, which was considered a contaminant.
CONCLUSIONS AND CLINICAL RELEVANCE Structural and functional integrity of the microwave antennas remained acceptable during repeated use and reprocessing for up to 4 cycles. However, there was a decrease in functional integrity at cycles 5 and 6. We suggest that these microwave antennas be subjected to > 3 reprocessing cycles. Antennas should be carefully examined before reuse.