V6-06: Fluoroscopic Roadmapping for Endourology

Video

Introductions and Objectives
During ureteroscopy and percutaneous nephrolithotomy orientation within the kidney is guided by two sources of information. The operator builds a mental map of the collecting system via visual infection and a retrograde pyelogram can also be performed to provide a visual snapshot. However, the contrast washes out and the visual reference is removed. In a kidney with complex architecture it can be challenging to navigate. We applied the use of fluoroscopic roadmapping used in angiography to provide real-time navigation within the kidney.

Methods
Fluroscopic roadmapping is an imaging process mode commonly used in vascular interventional cases. It is built into many mobile C-arm units used in the operating room. To create a roadmap first an image without contrast is recorded. Then images are captured as contrast is injected. The peak opacification from each frame is saved and then inverted to create a mask showing only the course of the contrast. The result is that immobile structures, such as ribs and vertebra, are erased and the path of the contrast appears white. When used in the kidney the mask acts as a transparent and stable nephrogram. Scopes and wires can be navigated with greater precision even in the absence of visual guidance.

Results
Fluoroscopic roadmapping has been beneficially applied to both ureteroscopy and percutaneous nephrolitotomy. With the collecting system continuously highlighted, complex anatomy such as duplicated systems and compound calyxes can be navigated with confidence. Radiography assisted navigation can augment visual navigation compromised by blood or debris. During percutaneous nephrolitotomy (PCNL), roadmapping allows more precise placement of the dilation balloon.

Conclusions
This novel application of fluoroscopy can be applied whenever a pyelogram would be helpful. With additional experience and optimization of the technical aspects this can provide another tool for complex endourologic procedures. Future research will be needed to quantify the benefits in regards to operative success, operative time, and radiation exposure.

Funding: none