[Augmented reality for image guided therapy (ARIGT) of kidney tumor during nephron sparing surgery (NSS): animal model and clinical approach].

Introduction: The main problem in nephron sparing surgery (NSS) is to preserve renal tumors oncological purity during the removal of the tumor with a margin of macroscopically unchanged kidney tissue while keeping the largest possible amount of normal parenchyma of the operated kidney. The development of imaging techniques, in particular IGT (Image Guided Therapy) allows precise imaging of the surgical field and, therefore, is essential in improving the effectiveness of NSS (increase of nephron sparing with the optimal radicality).

Aim: The aim of this study was to develop a method of the three-dimensional (3D) imaging of the kidney tumor and its lodge in the operated kidney using 3D laser scanner during NSS procedure. Additionally, the animal model of visualization was developed.

Material And Methods: The porcine kidney model was used to test the set built up with HD cameras and linear laser scanner connected to a laptop with graphic software (David Laser Scanner, Germany) showing the surface of the kidney and the lodge after removal the chunk of renal parenchyma. Additionally, the visualization and reconstruction was performed on animal porcine model. Moreover, 5 patients (3 women, 2 men) aged from 37 to 68 years (mean 56), diagnosed with kidney tumors in CT scans with a diameter of 3.7-6.9 cm (mean 4.9) were operated in our Department this year, scanning the surface during the treatment with the kidney tumor and kidney tumor after it is removed with a margin of renal tissue. In one case, the lodge of removed tumor was scanned. Dimensions in 3D reconstruction images of laser scans in the study of animal model and the images obtained intraoperatively were compared with the dimensions evaluated during preoperative CT scans, intraoperative measurements.

Results: Three-dimensional imaging laser scanner operating field loge resected tumor and the tumor on the kidney of animal models and during NSS treatments for patients with kidney tumors is possible in real time with an accuracy of -2 mm do +9 mm (+/- 3 mm). The duration of data acquisition by laser scanner and obtain three-dimensional image of the operating field takes an average of 13 seconds +/- 2 seconds. Movements associated with breathing and heart rate did not affect on the quality of the reconstruction. The imposition of the scanned surface texture occurs in real time, allowing you to identify renal parenchymal structures such as renal cortex, pyramids, pyelo-calices complex.

Conclusions: Imaging control of NSS procedures is possible in animal models and in real time intraoperatively. The comparison of tumor size and the tumor lodge obtained in preoperative CT scans with the measurements during NSS procedure provide the surgeon to assess the extent of macroscopic estimation of the resection. This procedure helps the surgeon in obtaining oncological radicality with saving as much normal tissue kidney as possible. Performance of the imaging methods should be evaluated on a larger group of patients with kidney tumors eligible for NSS treatment.