Minimally invasive approaches to treating tumors of the pharynx and larynx like trans-oral surgery have improved patient outcome, but challenges remain in localizing tumors for margin control. Introducing necessary retractors and scopes deforms the anatomy and the tumor, rendering preoperative imaging inaccurate and making tumor localization difficult. This paper describes a pipeline that uses preoperative imaging to generate a hybrid FEM-multibody model and then dynamically simulates tongue deformation due to insertion of an electromagnetically-tracked laryngoscope. We hypothesize that the simulation output will be a sufficient estimate of the final intraoperative state and thus provide the surgeon with more accurate guidance during surgical resection. This pipeline was trialed on a cadaver head. The skull, mandible, and laryngoscope were tracked, and fiducial clips were embedded in the tongue for calculating target localization error (TLE) between the simulated and real tongue deformation. Registration accuracies were 1.1, 1.3, and 0.8 mm, respectively, for the tracked skull, mandible, and laryngoscope, and tracking and segmentation validation between the last tracked frame and the ground-truth intraoperative CT was 0.8, 0.9, and 1.2 mm, respectively. TLE of 6.4±2.5 mm was achieved for the full pipeline, in contrast to the total tongue deformation of 37.2±11.4 mm (via tongue clips) between the preoperative and intraoperative CT. Use of tracking and deformation modeling is viable to estimate deformation of the tongue during laryngoscopy. Future work involves additional intraoperative data streams to help further refine model parameters and improve localization.
Tumor phantoms (TP) have been described for the purposes of training surgical residents and further understanding tissue characteristics in malignancy. To date, there has not been a tumor phantom described for the purposes of research and training in oncologic surgery of the head and neck focusing on the larynx and pharynx. With the goal of providing radiographic, visual, and physical mimicry of head and neck squamous cell carcinoma (HNSCC), a phantom was developed as a proposed training and research tool for trans-oral surgical procedures such as transoral laser microsurgery (TLM) and transoral robotic surgery (TORS). TP’s were constructed with an agar-gelatin chicken stock base to approximate reported physical properties, then glutaraldehyde and Omnipaque-350 were used as a fixative and to enhance CT-visualization respectively. Further, to ensure heterogeneity in radiographic imaging, other materials like olive oil and condensed milk were explored. These ingredients were combined with the use of a novel, 3D printed, syringe adaptor designed to allow for the direct injection of the liquid tumor into model tissue. TP’s fixed quickly in vivo upon implantation and were imaged using CT and segmented. This injection-based model was piloted in bovine tissue and verified in porcine tissue with excess Omnipaque-350 for volumetric reliability then optimized utilizing 6 well plates. Following radiographic optimization, the viscoelastic properties of TP’s were measured through uniaxial compression. We observed a Young’s modulus similar to published literature values and consistent reproducibility. Most notably, our proposed TP can be used by multiple specialties by altering the color and concentration of agar in the base solution to approximate physical properties.
In trans-oral surgeries, large intraoperative deformations limit the surgeons’ use of preoperative images to accurately resect tumors while traditional metal instruments render intraoperative images ineffective. A CT/MR compatible laryngoscopy system was developed previously to allow for the study of these deformations with intraoperative imaging. For this study, we compare the deformation analysis of two patient groups: those who had received prior radiation to the upper aerodigestive tract (irradiated) and those who have not (non-irradiated). We speculate that differences in tissue deformation exist between these two groups due to radiation-induced fibrosis (RIF) and that quantifying these distinct deformation patterns will lead to more patient-specific tissue modeling. Thirteen patients undergoing diagnostic laryngoscopy were recruited; five had been irradiated and eight had not. Artifact-free images were obtained and registered. Mandible, hyoid, and tongue region displacements were quantified. For the bony structures, significant differences were observed in certain displacement directions as well as magnitude, with the irradiated patient group experiencing less anatomical shift (non-irradiated vs irradiated: (Mandible) 12.6±3.6mm vs 7.9±2.8mm, p=0.029; (Hyoid) 13.3±3.1mm vs 9.0±1.8mm, p=0.019). For the tongue, average displacements of tongue fiducials were 26.2±11.1mm vs 22.9±8.4mm respectively (p=0.033). The data from this study can serve as ground truth to generate and evaluate upper aerodigestive tract deformation models to predict the intraoperative state and provide guidance to the surgeons.
Robot-assisted laparoscopic partial nephrectomies (RALPN) are performed to treat patients with locally confined renal carcinoma. There are well-documented benefits to performing partial (opposed to radical) kidney resections and to using robot-assisted laparoscopic (opposed to open) approaches. However, there are challenges in identifying tumor margins and critical benign structures including blood vessels and collecting systems during current RALPN procedures. The primary objective of this effort is to couple multiple image and data streams together to augment visual information currently provided to surgeons performing RALPN and ultimately ensure complete tumor resection and minimal damage to functional structures (i.e. renal vasculature and collecting systems). To meet this challenge we have developed a framework and performed initial feasibility experiments to couple pre-operative high-resolution anatomic images with intraoperative MRI, ultrasound (US) and optical-based surface mapping and kidney tracking. With these registered images and data streams, we aim to overlay the high-resolution contrast-enhanced anatomic (CT or MR) images onto the surgeon’s view screen for enhanced guidance. To date we have integrated the following components of our framework: 1) a method for tracking an intraoperative US probe to extract the kidney surface and a set of embedded kidney markers, 2) a method for co-registering intraoperative US scans with pre-operative MR scans, and 3) a method for deforming pre-op scans to match intraoperative scans. These components have been evaluated through phantom studies to demonstrate protocol feasibility.