Haptic Surgical Guidance for Prostate Biopsy
thesisposted on 28.11.2018, 00:00 by Martina anagrafica Berni
Prostate cancer (PCa), in addition to being the most widespread non-cutaneous cancerous form among American men, is the third prevalent factor of cancer-related mortality in the US. For this reason, early detection and accurate diagnosis are paramount for survival, increasing the possibilities of successful treatments. Non-invasive screening tests are rstly performed and, if the presence of cancerous tissue is suspected, prostate biopsy is executed to assess the presence of malignant lesions inside the gland. Blind systematic biopsy is the standard procedure allowing the extraction of cores through the guidance of transrectal ultrasound (TRUS) probe. This technique is ine cient and inaccurate because many samples must be taken in order to ensure some cores include cancerous tissue and small tumors might be missed. Whereas, if too many samples are extracted, the gland could be seriously damaged. Targeted biopsy aims to improve detection rate and prevent oversampling. The most common guidance still relies on TRUS, while the target de nition is based on magnetic resonance imaging (MRI). Limitations of this method resides in complexity and costs of the image fusion system. The TRUS guidance in this thesis project is substituted by a real-time tracking obtained through the haptic device. Moreover, a correction sensor is placed on the patient pelvis to take into account possible movements. The haptic surgical guidance for prostate biopsy main aim is to improve current prostate biopsy (PBx) procedure directing the surgeon toward the center of the tumors, identi ed with magnetic resonance elastography (MRE). Through MRE, mechanical properties of the tissue are acquired and a 3D map with sti ness distribution is consequently obtained. This technique provides an innovative diagnostic tool and targeting methodology, because cancerous areas are sti er respect surrounding healthy tissues. The mentioned property allows the identi cation of the center of the tumors through clustering techniques. In the virtual reality (VR) environment, pre-surgical planning can be conducted through the visual and haptic feedbacks obtained interacting with the simulated prostate. Before the procedure, image registration is fundamental to match information from the di erent imaging techniques and also to create coherence with anatomical data. Finally, the surgeon is guided towards the identi ed targets, through the force feedback provided by the haptic device.