A comparative study of sono‐urethrography using saline, agitated saline, and an ultrasound contrast agent in normal beagles

Abstract

Sono-urethrography is a technique used to evaluate the integrity of the urethra utilizing fluid dilation of the urethral lumen. The purpose of this prospective, method comparison, pilot study was to investigate the feasibility of sono-urethrography in male dogs and to compare the quality of the images obtained using three different contrast solutions. The prostatic, membranous, and penile urethra was evaluated using saline, agitated saline, and ultrasound contrast agent (Sonovue) in 10 adult, male Beagles. Visibility of the urethral wall was better with sono-urethrography than with conventional ultrasonography, and the conspicuity of urethra could be assessed using all solutions.Hyperechoic lines created by agitated saline and Sonovue were more useful than anechoic saline in allowing identification of the urethra. Visibility scores for the internal margin of the urethral wall using sono-urethrography were significantly higher with saline and one-minute post agitated saline injection. However, the individual layers of the urethral wall could not be observed, regardless of the contrast solution used. Shadowing created by the pelvic bone deteriorated the window through which the urethra could be visualized, and this could not be overcome using sono-urethrography.The results of this study indicated that sono-urethrography is a feasible option for the visualization of the male urethra in dogs. The authors recommend sono-urethrography using saline or agitated saline infusion to evaluate the urethral wall and lumen. Sonourethrography using ultrasound contrast agent can be applied to assess the integrity of the urethra by improving its conspicuity.

Evaluation of urethral thickness using ultrasonography in healthy small-breed dogs

“…In a recent study, although their purpose was not to make a reference range of the urethral wall thickness, the thickness of the urethral wall of 10 male Beagle dogs was measured by conventional ultrasound without contrast injection. In the previous study, the mean value of the urethral wall thickness in membranous urethra was 1.4 ± 0.3 mm ( 14 ). This value is smaller than in our study, but there are differences in measurement location and method between the two studies.…”

“…When the urethral lumen is distended with urine, the lumen appears anechoic to hypoechoic due to urine and the mucosal lining may be distinguished. However, in most dogs, the urethral lumen is collapsed, and in those cases, the urethral lumen and mucosal lining are not observed in ultrasound images ( 14 ). The normal urethral lumen is collapsed without continuous excretion of urine ( 14 ); therefore, all dogs included in this study had a collapsed urethral lumen.…”

“…However, in most dogs, the urethral lumen is collapsed, and in those cases, the urethral lumen and mucosal lining are not observed in ultrasound images ( 14 ). The normal urethral lumen is collapsed without continuous excretion of urine ( 14 ); therefore, all dogs included in this study had a collapsed urethral lumen. We measured the distance from the ventral hyperechoic line to the dorsal hyperechoic line (the leading edge to the trailing edge) using electronic calipers ( Figures 1A,B ).…”

“…Non-invasive or minimally invasive imaging modalities are used for evaluation of the urethra ( 14 – 17 ). Radiography is not available for urethral evaluation because it does not enable visualization of the urethra.…”

“…CT and MRI have the disadvantages of being more expensive with relatively longer scanning time. In contrast, ultrasound can clearly visualize the urethral wall even if it is adjacent to the surrounding soft tissue and has the additional benefits of a lower cost, shorter procedure time, not requiring anesthesia, rarely requiring sedation, and avoiding patient or operator exposure to ionizing radiation ( 14 ). Therefore, we used ultrasonography to measure total urethral thickness in this study.…”