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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session E

Poster F4 - The Impact of Probe Pressure on Ultrasound Imaging for Monitoring Rat Bladder Morphology and Volume

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Bladder outlet obstruction (BOO) is a condition in which the outlet to the bladder is constricted, reducing outflow of urine. The most common cause of BOO in men is benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate gland. In early stages of BOO, the bladder is capable of increasing its muscle mass to generate sufficiently high pressures to overcome the rise in outlet resistance. However, prolonged elevation in voiding pressures induces progressive changes to the bladder wall that cause lower urinary tract symptoms (LUTS). About one-third of men over the age of 50 will experience moderate to severe LUTS due to BOO [1-2]. Unfortunately, 30% of prostrate surgeries to treat BOO are ineffective. In an ongoing collaborative research program, we are developing the first digital twin of the bladder that can be used to design and test improved treatments for BOO. This model is based on data obtained from an established rat model of BOO. Ultrasound (US) measurements of the bladder are an important component of this data set. The focus of the present study is the design of an US protocol for probe pressure with high reproducibility of the bladder morphology and volume measurements.

Materials and

Methods:  To assess the impact of probe pressure, we performed two ultrasound images on a healthy rat with a high and low amount of pressure. To investigate the experiment's reproducibility, we performed US imaging on a rat three times, considering minimal probe pressure. After performing each experiment, we utilized an in-house semi-automated deep-learning-based image segmentation tool to segment the bladder in the obtained ultrasound stacks [4]. Then, using an in-house 3D reconstruction tool, we generated 3D models of the bladder for each experiment and measured their volumes [4].

Results, Conclusions, and Discussions: Figure 1 presents the results of the first experiment assessing the impact of probe pressure on rat bladder morphology and volume measurements. These results showed that probe pressure can result in a 34.3% reduction in bladder volume measurement compared to the case with minimal probe pressure. The morphology of the bladder obtained from the two stacks also indicates substantial variations, indicating the necessity to perform rat ultrasound imaging tasks using minimal probe pressures. Figure 2 shows the results of the reproducibility analysis. Repeating the ultrasound imaging for the rat's full bladder resulted in less than 4% variations in volume measurements compared to the average of calculated volume measurements among the three stacks.
In summary, the results from the first experiment highlighted the sensitivity of bladder shape to the amount of pressure applied during ultrasound imaging. Excessive pressure can alter bladder morphology, suggesting imaging should be performed with minimal pressure to avoid deforming the bladder and altering its shape. The second experiment demonstrated the reproducibility of bladder volume measurements when a low probe pressure was used, indicating ultrasound imaging, when performed with minimal probe pressure, is a reliable method for monitoring in-vivo bladder shape and volume in rats.

Acknowledgements (Optional):  The authors gratefully acknowledge funding from the NIH R01 DK133434.