Probe-based Confocal Laser Endomicroscopy of the Urinary Tract: The Technique

The aim of the following experiment is to demonstrate in vivo microscopy using probe based confocal laser endo microscopy in a patient undergoing transurethral resection of a bladder tumor. This is achieved by first using white light cystoscopy to visualize the entire urothelium of the bladder and to note any abnormal or suspected mucosal lesions. As a second step, a contrast agent is instilled intra ally providing the fluorescence contrast needed for visualization with the confocal laser endo microscope in the third step in vivo microscopy of each area of interest is performed and the cellular micro architectural and vascular features of the tissue are noted.

Ultimately, the in vivo microscopy findings can be compared to the histopathological analysis of the biopsies of the regions of interest. Demonstrating the procedure will be Dr.Joseph Leal, the urologic surgeon, who developed the application of the probe based confocal laser endo microscopy for the urinary tract In the operating room. After the subject is in the lithotomy position, begin by inserting a rigid cystoscope through the urethra using standard white light cystoscopy to surveil the regions of the bladder under white light.

Mark the regions of interest for confocal laser endo microscopy with a resection loop. Other macroscopic optical imaging modalities, such as fluorescent cystoscopy and narrow band imaging may be used at this step to identify additional areas of suspicion, now insert a sterile urinary catheter into the bladder using a 60 milliliter catheter. Tip syringe, instill the diluted contrast agent by gravity.

Next, clamp the urinary catheter to hold the contrast agent in dwelling. After five minutes, drain the agent from the bladder. Then pour 240 to 300 milliliters of normal saline into the 60 milliliter syringe to wash out any residual contrast from the bladder for intravenous injection of fluorescein.

Draw one milliliter of fluorescein into a syringe. Attach the syringe to the intravenous access point and inject 0.5 to one milliliter of the fluorescein intravenously as a bolus flushing the line with normal saline. After the contrast agent has been injected, remove a sterile confocal laser endo microscopy imaging probe from the packaging and connect it to the laser scanning unit.

Next, warm up and calibrate the imaging probe according to the manufacturer's instructions, and then reinsert the rigid cystoscope with a zero degree lens into the bladder. Now advance the confocal endo microscopy imaging Probe along the working channel of the cystoscope with the tip just beyond the cystoscope under white light. Locate the previously marked regions of interest as the imaging probe scans the region of interest.

Record the images for future analysis. Then use the operator's hand to manipulate the confocal endo microscopy imaging. Probe for direct on fast contact of the regions of interest for optical sectioning of the regions of interest.

Gently increase and decrease the pressure to the imaging probe while maintaining direct contact To reach tumors located at the interior bladder. Use a standard AL elbow and bridge to facilitate the deflection of the imaging probe for direct contact with the region of interest. If desired, obtain cold cut biopsies from any corresponding regions of interest that was scanned by the confocal laser endo microscopy.

Upon completion of the imaging, remove the confocal endo microscopy imaging probe from the working channel. While attempting this procedure, it is important to remember to wash excess fluorescein from within the bladder before imaging and to maintain 90 degree contact between a probe and the mucosal surface. This first image is from a representative white light cystoscopy with an intravascularly stained papillary tumor.

Note the 2.6 millimeter imaging probe visible at the bottom of the image. These two images are representative confocal laser endo microscopy images obtained from two different bladder tumors using intravesical and intravenous fluorescein respectively. Given that the imaging probes may be interchanged between the different types of cystoscopes confocal laser, endo microscopy can be combined with other emerging imaging modalities, which may improve the diagnostic accuracy of either technology by itself, including fluorescent cystoscopy as shown here, and narrow band imaging as shown here.

So this method may provide insight into bladder cancer. It may be applied to other systems such as upper tract urothelial carcinomas, which may be difficult to diagnose in biopsy.