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- Author or Editor: William Tod Drost x
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Abstract
Objective—To quantitatively determine echogenicity of the liver and renal cortex in clinically normal cats.
Animals—17 clinically normal adult cats.
Procedure—3 ultrasonographic images of the liver and the right kidney were digitized from video output from each cat. Without changing the ultrasound machine settings, an image of a tissue-equivalent phantom was digitized. Biopsy specimens of the right renal cortex and liver were obtained for histologic examination. Mean pixel intensities within the region of interest (ROI) on hepatic, renal cortical, and tissue-equivalent phantom ultrasonographic images were determined by histogram analysis. From ultrasonographic images, mean pixel intensities for hepatic and renal cortical ROI were standardized by dividing each mean value by the mean pixel intensity from the tissue-equivalent phantom.
Results—The mean (± SD) standardized hepatic echogenicity value was 1.06 ± 0.02 (95% confidence interval, 1.02 to 1.10). The mean standardized right renal cortical echogenicity value was 1.04 ± 0.02 (95% confidence interval, 1.01 to 1.08). The mean combined standardized hepatic and renal cortical echogenicity value was 1.02 ± 0.05 (95% confidence interval, 0.99 to 1.04).
Conclusions and Clinical Relevance—Quantitative determination of hepatic and renal cortical echogenicity in cats is feasible, using histogram analysis, and may be useful for early detection of diffuse parenchymal disease and for serially evaluating disease progression. (Am J Vet Res 2000;61:1016–1020)
Abstract
Objectives—To quantify direction and velocity of blood flow in hepatic veins in dogs under different hemodynamic conditions by use of pulsed-wave Doppler ultrasonography.
Animals—10 healthy dogs.
Procedure—Dogs were anesthetized, and venous flow velocities in the quadrate lobe were measured. Arterial blood pressure, right atrial pressure, pulmonary artery pressure, and cardiac output were measured simultaneously. The timing of each waveform during the cardiac cycle was used to identify velocity profiles. Peak waveform velocities were measured during conditions of light anesthesia with isoflurane (baseline; period 1), cardiovascular depression following administration of highdose isoflurane and esmolol IV (period 2), cardiovascular depression with crystalloid volume expansion (period 3), and high cardiac output induced with dobutamine (period 4). Hemodynamic measurements and maximum waveform velocities were compared among the 4 periods by use of an ANOVA and univariate and multivariate linear regression.
Results—During each study period, 4 distinct, lowvelocity waves were identified. Mean velocities recorded during period 1 were as follows: retrograde atrial contraction a-wave, 7.3 cm/s; antegrade systolic S-wave, 15.0 cm/s; retrograde venous return v-wave, 2.7 cm/s; and antegrade diastolic D-wave, 11.4 cm/s. Mean S:D ratio was 1.27. During periods 3 and 4, Swave velocity increased; D-wave velocity was highest during period 4.
Conclusions and Clinical Relevance—Consistent hepatic venous velocity profiles were observed in healthy dogs under different hemodynamic conditions. These findings provide baseline values that may be useful in evaluating clinical cases, but further study involving healthy, awake dogs and dogs with cardiac and hepatic diseases is required. (Am J Vet Res 2004;65:734–740)
Abstract
Objective—To determine maximum extrarenal plasma clearance of technetium-99m-mercaptoacetyltriglycine (99mTc–MAG3) and maximum extrarenal hepatic uptake of 99mTc–MAG3 in cats.
Animals—6 clinically normal adult cats.
Procedure—Simultaneously, baseline plasma clearance and camera-based uptake of 99mTc–MAG3 were determined in anesthetized cats. Double exponential curves were fitted to plasma clearance data. Injected dose was divided by area under the curve and body weight to determine 99mTc–MAG3 clearance. Regions of interest were drawn around kidneys and liver, and percentage dose uptake was determined 1 to 3 minutes after injection. After bilateral nephrectomy, simultaneous extrarenal plasma clearance and camera- based hepatic uptake of 99mTc–MAG3 were evaluated in each cat.
Results—Mean ± SD baseline plasma clearance and extrarenal clearance were 5.29 ± 0.77 and 0.84 ± 0.47 mL/min/kg, respectively. Mean extrarenal clearance (as a percentage of baseline plasma clearance) was 16.06 ± 7.64%. For right, left, and both kidneys, mean percentage dose uptake was 9.42 ± 2.58, 9.37 ± 0.86, and 18.79 ± 2.47%, respectively. Mean hepatic percentage dose uptake before and after nephrectomy was 12.95 ± 0.93 and 21.47 ± 2.00%, respectively. Mean percentage change of hepatic uptake after nephrectomy was 166.89 ± 23.19%.
Conclusions and Clinical Relevance—In cats, extrarenal clearance of 99mTc–MAG3 is higher than that of other species; therefore, 99mTc–MAG3 is not useful for estimation of renal function in felids. Evaluation of renal function in cats may be more accurate via camera- based versus plasma clearance-based methods because camera-based studies can discriminate specific organs. (Am J Vet Res 2003;64:1076–1080)
