Objective—To test the effects of computed tomography (CT) image plane and window settings on diagnostic certainty for CT characteristics associated with dysplastic elbow joints (elbow joint dysplasia) in dogs and to provide optimal display guidelines for these CT characteristics.
Sample Population—CT images of 50 dysplastic elbow joints from 49 lame dogs and 10 elbow joints from 5 sound dogs.
Procedures—CT image data were obtained in transverse, sagittal, and dorsal planes. Each plane was examined by use of 3 Hounsfield unit (HU) window settings. Two veterinary radiologists independently evaluated sets of CT images for evidence of 7 CT characteristics. Effect of elbow joint status, image plane, and window settings on diagnostic certainty for these CT characteristics was tested by use of a visual analogue scale.
Results—Diagnostic certainty for abnormalities of the medial coronoid process (MCP) and radial incisure was highest in the transverse plane, subchondral defects or sclerosis of the trochlea humeri was highest in the dorsal plane, and joint incongruity was highest in the sagittal plane. Certainty for hypoattenuating subchondral defects or fissures was highest at 2,500 or 3,500 HUs, whereas certainty for subchondral sclerosis was highest at 1,500 HUs and lowest at 3,500 HUs.
Conclusions and Clinical Relevance—Diagnostic certainty for CT characteristics of elbow joint dysplasia in dogs was affected by image display variables. Diagnostic certainty for altered subchondral bone density was primarily influenced by window settings, whereas structural MCP abnormalities and joint incongruity were influenced most by image plane.
Objective—To evaluate the correlation between the
half-time of liquid-phase gastric emptying (T50) determined
by use of nuclear scintigraphy, using technetium
Tc 99m pentetate, and absorption variables of
orally administered acetaminophen in horses with
experimentally delayed gastric emptying.
Animals—6 mature horses.
Procedure—Delayed gastric emptying was induced
by IV injection of atropine sulfate. Twenty minutes
later, acetaminophen and technetium Tc 99m pentetate
were administered simultaneously via nasogastric
tube. Serial lateral images of the stomach region
were obtained, using a gamma camera. Power exponential
curves were used for estimation of T50 and
modified R2 values for estimation of goodness-of-fit of
the data. Serial serum samples were obtained, and
acetaminophen concentration was determined, using
fluorescence polarization immunoassay. Maximum
serum concentration (Cmax), time to reach maximum
serum concentration (Tmax), area under the curve for
480 minutes, and the appearance rate constant were
determined, using a parameter estimation program.
Correlations were calculated, using a Spearman rank
Results—A significant correlation was detected
between T50 determined by use of scintigraphy and
Tmax determined by use of acetaminophen absorption.
Correlation between T50 and other absorption
variables of acetaminophen was not significant.
Conclusions and Clinical Relevance—The acetaminophen
absorption method was a valid technique in
this model of delayed gastric emptying in horses. The
method may be a valuable tool for use in research as
well as in clinical evaluation of gastric emptying in
horses. (Am J Vet Res 2002;63:170–174)
Objective—To devise a technique for gradual occlusion
of the caudal vena cava in dogs and determine
effects of complete occlusion of the caudal vena cava.
Animals—8 mixed-breed hounds that weighed
between 25 and 30 kg.
Procedure—Baseline evaluation of dogs included
serum biochemical analyses and determination of
glomerular filtration rate (GFR) with dynamic renal
scintigraphy and plasma clearance analysis. An
occluder was placed around the vena cava in the
region cranial to the renal veins. The occluder was
attached to a vascular access port. The vena cava was
gradually occluded over 2 weeks. The GFR was measured
every 2 weeks after surgery, and venograms
were performed every 3 weeks after surgery. Blood
samples were collected every 48 hours for the first
week and then weekly thereafter to measure BUN
and creatinine concentrations and activities of alanine
transaminase, alkaline phosphatase, and creatinine
kinase. Dogs were euthanatized 6 weeks after
surgery, and tissues were submitted for histologic
examination. The GFR and biochemical data were
compared with baseline values.
Results—Gradual occlusion of the caudal vena cava
was easily and consistently performed with this
method, and adverse clinical signs were not detected.
Formation of collateral vessels allowed overall
GFR to remain constant despite a decrease in function
of the left kidney. Measured biochemical values
did not deviate from reference ranges.
Conclusions and Clinical Relevance—Gradual
occlusion of the caudal vena cava may allow removal
of adrenal gland tumors with vascular invasion that
would otherwise be difficult or impossible to resect.
(Am J Vet Res 2003;64:1347–1353)