Quantification of hepatic and renal cortical echogenicity in clinically normal cats

William Tod Drost Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK74078.

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George A. Henry Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK74078.
Present address is Department of Large Animal Medicine & Surgery, Texas A&M University, College Station, TX 77843-4475.

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James H. Meinkoth Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK74078.

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J. Paul Woods Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK74078.
Present address is Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada, N1G 2W1.

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Terry W. Lehenbauer Department of Infectious Diseases and Physiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK74078.

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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

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)

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