Measurement of acoustic backscatter and attenuation in the liver of dogs with experimentally induced steroid hepatopathy

Robert T. O'Brien From the Departments of Surgical Sciences (O'Brien) and Pathobiology (Steinberg), School of Veterinary Medicine, and Department of Medical Physics (Zagzebski, Lu), Medical School, University of Wisconsin, Madison, WI 53706.

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 DVM, MS
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James A. Zagzebski From the Departments of Surgical Sciences (O'Brien) and Pathobiology (Steinberg), School of Veterinary Medicine, and Department of Medical Physics (Zagzebski, Lu), Medical School, University of Wisconsin, Madison, WI 53706.

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Zheng Feng Lu From the Departments of Surgical Sciences (O'Brien) and Pathobiology (Steinberg), School of Veterinary Medicine, and Department of Medical Physics (Zagzebski, Lu), Medical School, University of Wisconsin, Madison, WI 53706.

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Howard Steinberg From the Departments of Surgical Sciences (O'Brien) and Pathobiology (Steinberg), School of Veterinary Medicine, and Department of Medical Physics (Zagzebski, Lu), Medical School, University of Wisconsin, Madison, WI 53706.

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Abstract

Objective

To determine the usefulness of a new method of measuring acoustic backscatter and attenuation in the liver of dogs with experimental steroid-induced hepatopathy.

Animals

10 clinically normal dogs.

Procedure

Steroid hepatopathy was induced by daily injections of prednisone (2 mg/kg of body weight, IM). Dogs were evaluated histologically and were sonographically imaged on days 0, 3, 7, 10, and 14. Acoustic backscatter and attenuation were measured from in vivo images of dogs, using a video signal method, and compared with results obtained from analysis of the unprocessed radio frequency signal.

Results

Histologic evaluation revealed midzonal, predominantly water-filled vacuoles in hepatocytes by day 7, which persisted for the remainder of the study and significantly (P = 0.0001) increased liver weight on day 14. Attenuation and backscatter increased during the experimental period. Mean effective attenuation difference was higher (P = 0.015) in the liver imaged through a left paraxyphoid window in experimental dogs by day 3. Significantly (P < 0.05) greater attenuation persisted in the liver of experimental dogs throughout the experimental period. Mean backscatter ratio was significantly increased (P = 0.02) by day 10. Uncorrected pixel intensity of the liver in 2 experimental dogs was approximately equal to that of the spleen on day 10 and greater than that of the spleen on day 14.

Conclusion

Administration of prednisone to dogs results in increased acoustic backscatter and attenuation in the liver.

Clinical Relevance

The video signal method is a sensitive technique for detecting subtle acoustic changes in the liver of dogs. (Am J Vet Res 1996;57:1690–1694)

Abstract

Objective

To determine the usefulness of a new method of measuring acoustic backscatter and attenuation in the liver of dogs with experimental steroid-induced hepatopathy.

Animals

10 clinically normal dogs.

Procedure

Steroid hepatopathy was induced by daily injections of prednisone (2 mg/kg of body weight, IM). Dogs were evaluated histologically and were sonographically imaged on days 0, 3, 7, 10, and 14. Acoustic backscatter and attenuation were measured from in vivo images of dogs, using a video signal method, and compared with results obtained from analysis of the unprocessed radio frequency signal.

Results

Histologic evaluation revealed midzonal, predominantly water-filled vacuoles in hepatocytes by day 7, which persisted for the remainder of the study and significantly (P = 0.0001) increased liver weight on day 14. Attenuation and backscatter increased during the experimental period. Mean effective attenuation difference was higher (P = 0.015) in the liver imaged through a left paraxyphoid window in experimental dogs by day 3. Significantly (P < 0.05) greater attenuation persisted in the liver of experimental dogs throughout the experimental period. Mean backscatter ratio was significantly increased (P = 0.02) by day 10. Uncorrected pixel intensity of the liver in 2 experimental dogs was approximately equal to that of the spleen on day 10 and greater than that of the spleen on day 14.

Conclusion

Administration of prednisone to dogs results in increased acoustic backscatter and attenuation in the liver.

Clinical Relevance

The video signal method is a sensitive technique for detecting subtle acoustic changes in the liver of dogs. (Am J Vet Res 1996;57:1690–1694)

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