01384-A: Improved Imaging to Monitor Therapy Response of Urinary Bladder Cancer Using 3D Volume Ultrasonography
Grant Status: Closed
The goal of this research study was to determine if three-dimensional ultrasonography (3DUS) could provide an improved way to image and measure urinary bladder tumors, as the currently available methods are either inconsistent, cost-prohibitive or place an undue physical burden on the patient. In the study, the investigators used state of the art 3DUS equipment to measure bladder tumors in 10 dogs and compared these measurements to those made, of the same tumors, with conventional two-dimensional ultrasound (2DUS) and computed tomography (CT), using CT as the gold standard method of measurement. The information gleaned from this study met and exceeded our expectations. First, they found that 3DUS can be used interchangeably with CT to make accurate measurements of bladder tumor volume. This is important because 3DUS is an inexpensive measurement method when compared to CT. Also, there is no need for anesthesia using 3DUS. CT cannot be performed without anesthesia in veterinary patients, which adds substantially to the cost of each study. These two factors form a solid new cornerstone which will aid oncologists in identifying the most efficient routes of bladder cancer treatment. Second, with 3DUS they found that repeated measurements of the same tumor showed very little difference. This shows that the same operator will produce very accurate measurements and suggests that this technique might be used by several different operators to image the same patient, and all would find a very similar tumor size. This is important because it allows flexibility in imaging the patients when monitoring remission, stability or progression of cancer. A separate study using various operators to measure tumor size with 3DUS is needed to prove this contention. Third, they found that there is no statistical difference in bladder tumor size when the bladder filled to different levels. This is new, valuable information because it has previously been assumed that the amount of urine in a bladder, and therefore the pressure present in the bladder lumen, may cause some or all of these tumors to change size. This finding negates the need to catheterize patients to empty or fill the bladder to accomplish a uniform size, and also eliminates the need for patients to wait, sometimes hours at a time, to fill their bladder naturally so that the tumor can be imaged. Last, and in addition to the original proposed work, they found that the 3DUS volumes of the tumors do not need to be excessively segmented, or sliced, with a special computer program, in order to achieve an accurate tumor volume. They divided each of the tumors into four, eight and 12 segments, or pieces, to measure size and found that eight segments provides the optimum balance between accuracy and time spent analyzing each tumor mass. An improved imaging method is now available for monitoring therapeutic response in urinary bladder tumors. The results of this study are encouraging and met or exceeded all of the expectations set forth at the beginning of the project. The 3DUS method is applied with the same efficiency as a conventional 2DUS with slightly more time required to obtain each image volume. While the processing of the information after the exam requires a slightly larger time investment than that required in 2DUS these investments are balanced by the increased accuracy and consistency of measurements made of the patient's tumor. It is estimated that only 10 additional minutes are needed for this method versus conventional 2DUS. This is encouraging news for clinicians and owners of dogs with urinary bladder TCC and is currently being implemented at our institution.
Naughton, J. F., Widmer, W. R., Constable, P. D., & Knapp, D. W. (2012). Accuracy of three-dimensional and two-dimensional ultrasonography for measurement of tumor volume in dogs with transitional cell carcinoma of the urinary bladder. American Journal of Veterinary Research, 73(12), 1919–1924. https://doi.org/10.2460/ajvr.73.12.1919
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