Volumetric in-vivo visualization of upper urinary tract tumors using optical coherence tomography, "Beyond the Abstract," by Mieke T. J. Bus, MD and Jean J.M.C.H. de la Rosette, MD, PhD

BERKELEY, CA (UroToday.com) - We recently published our study on in vivo optical coherence tomography (OCT) as a new diagnostic tool for upper urinary tract urothelial carcinoma (UUT-UC). UUT-UC diagnosis is based on imaging, endoscopy, cytology, and histology. Although each technique is important to obtain a proper diagnosis on tumour stage and grade, they all have their limitations resulting in a high rate of tumour upgrading and upstaging after nephroureterectomy.

The reference standard treatment in patients with UUT-UC suitable for surgery is radical nephroureterectomy. UUT-UC only has to be confirmed and exact tumour stage and grade is disregarded during the diagnostic work-up. However, patients with low-grade and low-stage disease have the possibility to undergo endoscopic treatment nowadays. This new treatment modality makes optimal tumor staging and grading mandatory, in order to attain optimal patient selection for tailored treatment.

Since current diagnostics all have their limitations, search for a new diagnostic tool that can provide reliable information on tumor grade and stage is of utmost importance. OCT is a high resolution imaging technique, originally used in cardiology and ophthalmology. Nowadays, it is used in many different applications, especially in epithelial tissues. OCT is analogous to ultrasound but uses backscattered near-infrared light instead of black reflected sound waves to produce images. OCT is capable of producing cross-sectional images with µm scale resolution on which the anatomical layers of the ureter are visible, including the basement membrane. On these cross-sectional images, tumor lesions can be visualized. Tumor stage can be accurately determined by image bases assessment of a visible basement membrane underneath the tumor lesion, or interruption of the basement membrane by the lesion. Interruption of the basement membrane by a lesion indicates invasiveness.

This new imaging technique does not only provide accurate information on tumor stage, but we have demonstrated in this pilot study that OCT has also the potential to provide the urologist with real-time information on tumour grade. As light scattering decreases OCT signal magnitude with depth, this signal decrease can be quantified by the attenuation coefficient (µoct). During carcinogenesis, changes occur in the cellular architecture, like increased nuclear-to-cytoplasm ratio and increased number of mitochondria. These changes in cellular content determine light scattering properties. Therefore lesion grade can be determined by correlating with µoct. Although this study is limited by a small study population, we were able to demonstrate a significant difference between µoct in low-grade tumours and µoct in high-grade tumours.

Therefore, OCT could be a helpful diagnostic tool for UUT-UC, providing the endoscopist with accurate information on tumor grade and stage. This makes OCT a promising new tool for optical diagnostics in upper urinary tract abnormalities. An extended in vivo human study should confirm if OCT is able to differentiate between low-grade, high-grade and CIS lesions. Secondly, sensitivity and specificity testing of OCT will have to be determined.

Written by:
Mieke T. J. Bus, MD and Jean J.M.C.H. de la Rosette, MD, PhD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

Department of Urology, Academic Medical Center, Amsterdam, The Netherlands

Volumetric in-vivo visualization of upper urinary tract tumors using optical coherence tomography: A pilot study - Abstract

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