Marina Carbone

How to build patient-specific synthetic abdominal anatomies. An innovative approach from physical toward hybrid surgical simulators

According to literature evidence, simulation is of the utmost importance for training and innovative surgical strategies assessment. At present commercial physical simulators are limited to single or only a few anatomical structures and these are often just standard anatomies.

Value of multidetector computed tomography image segmentation for preoperative planning in general surgery

BackgroundUsing practical examples, this report aims to highlight the clinical value of patient-specific three-dimensional (3D) models, obtained segmenting multidetector computed tomography (MDCT) images, for preoperative planning in general surgery.MethodsIn this study, segmentation and 3D model generation were performed using a semiautomatic tool developed in the authors’ laboratory. Their segmentation procedure is based on the neighborhood connected region-growing algorithm that, appropriately parameterized for the anatomy of interest and combined with the optimal segmentation sequence, generates good-quality 3D images coupled with facility of use. Using a touch screen monitor, manual refining can be added to segment structures unsuitable for automatic reconstruction. Three-dimensional models of 10 candidates for major general surgery procedures were presented to the operating surgeons for evaluation. A questionnaire then was administered after surgery to assess the perceived added value of the new technology.ResultsThe questionnaire results were very positive. The authors recorded the diffuse opinion that planning the procedure using a segmented data set allows the surgeon to plan critical interventions with better awareness of the specific patient anatomy and consequently facilitates choosing the best surgical approach.ConclusionsThe benefit shown in this report supports a wider use of segmentation software in clinical practice, even taking into account the extra time and effort required to learn and use these systems.

An optimal design for patient‐specific templates for pedicle spine screws placement

Currently, pedicle screws are positioned using a free‐hand technique or under fluoroscopic guidance, with error in the range 10–40%, depending on the skill of the surgeon.

Augmented reality visualization of deformable tubular structures for surgical simulation

Surgical simulation based on augmented reality (AR), mixing the benefits of physical and virtual simulation, represents a step forward in surgical training. However, available systems are unable to update the virtual anatomy following deformations impressed on actual anatomy.

Assessment of DICOM Viewers Capable of Loading Patient-specific 3D Models Obtained by Different Segmentation Platforms in the Operating Room.

Patient-specific 3D models obtained by the segmentation of volumetric diagnostic images play an increasingly important role in surgical planning. Surgeons use the virtual models reconstructed through segmentation to plan challenging surgeries. Many solutions exist for the different anatomical districts and surgical interventions. The possibility to bring the 3D virtual reconstructions with native radiological images in the operating room is essential for fostering the use of intraoperative planning. To the best of our knowledge, current DICOM viewers are not able to simultaneously connect to the picture archiving and communication system (PACS) and import 3D models generated by external platforms to allow a straight integration in the operating room. A total of 26 DICOM viewers were evaluated: 22 open source and four commercial. Two DICOM viewers can connect to PACS and import segmentations achieved by other applications: Synapse 3D® by Fujifilm and OsiriX by University of Geneva. We developed a software network that converts diffuse visual tool kit (VTK) format 3D model segmentations, obtained by any software platform, to a DICOM format that can be displayed using OsiriX or Synapse 3D. Both OsiriX and Synapse 3D were suitable for our purposes and had comparable performance. Although Synapse 3D loads native images and segmentations faster, the main benefits of OsiriX are its user-friendly loading of elaborated images and it being both free of charge and open source.

High frequency poroelastic waves in hydrogels.

In this work a continuum model for high frequency poroelastic longitudinal waves in hydrogels is presented. A viscoelastic force describing the interaction between the polymer network and the bounded water present in such materials is introduced. The model is tested by means of ultrasound wave speed and attenuation measurements in polyvinylalcohol hydrogel samples. The theory and experiments show that ultrasound attenuation decreases linearly with the increase in the water volume fraction beta of the hydrogel. The introduction of the viscoelastic force between the bounded water and the polymer network leads to a bi-phasic theory, showing an ultrasonic fast wave attenuation that can vary as a function of the frequency with a non-integer exponent in agreement with the experimental data in literature. When beta tends to 1 (100% of interstitial water) due to the presence of bounded water in the hydrogel, the ultrasound phase velocity acquires higher value than that of pure water. The ultrasound speed gap at beta=1 is confirmed by the experimental results, showing that it increases in less cross-linked gel samples which own a higher concentration of bounded water.

A new head-mounted display-based augmented reality system in neurosurgical oncology: a study on phantom

Abstract Purpose: Benefits of minimally invasive neurosurgery mandate the development of ergonomic paradigms for neuronavigation. Augmented Reality (AR) systems can overcome the shortcomings of commercial neuronavigators. The aim of this work is to apply a novel AR system, based on a head-mounted stereoscopic video see-through display, as an aid in complex neurological lesion targeting. Effectiveness was investigated on a newly designed patient-specific head mannequin featuring an anatomically realistic brain phantom with embedded synthetically created tumors and eloquent areas. Materials and methods: A two-phase evaluation process was adopted in a simulated small tumor resection adjacent to Broca’s area. Phase I involved nine subjects without neurosurgical training in performing spatial judgment tasks. In Phase II, three surgeons were involved in assessing the effectiveness of the AR-neuronavigator in performing brain tumor targeting on a patient-specific head phantom. Results: Phase I revealed the ability of the AR scene to evoke depth perception under different visualization modalities. Phase II confirmed the potentialities of the AR-neuronavigator in aiding the determination of the optimal surgical access to the surgical target. Conclusions: The AR-neuronavigator is intuitive, easy-to-use, and provides three-dimensional augmented information in a perceptually-correct way. The system proved to be effective in guiding skin incision, craniotomy, and lesion targeting. The preliminary results encourage a structured study to prove clinical effectiveness. Moreover, our testing platform might be used to facilitate training in brain tumour resection procedures.

Anthropomorphic ultrasound elastography phantoms — Characterization of silicone materials to build breast elastography phantoms

In this paper a mechanical characterization of low cost and simply available materials to build efficient anthropomorphic ultrasound elastography phantoms is described. The class of silicone materials was selected because of their deformability, durability and the possibility of reproducing specific tissue properties and shapes. Innovative formulations of silicone mixtures with echogenic and/or softening additives were tested. The proposed models have good acoustic properties and tactile feedback; moreover they are durable and do not require special storage since they do not dehydrate or decompose over time.

Application of a New Wearable Augmented Reality Video See-Through Display to Aid Percutaneous Procedures in Spine Surgery

In mini-invasive surgery, the surgeon operates without a direct visualization of the patient’s anatomy. In image-guided surgery, solutions based on augmented reality (AR) represent the most promising ones. The aim of this study was to evaluate the efficacy of a new wearable AR system as aid in the performance of percutaneous procedures in spine surgery. Our solution is based on a video see-through head mounted display (HMD) and it allows the augmentation of video frames acquired by two external cameras with the rendering of patient-specific 3D models obtained elaborating radiological images. We tested the system on an in vitro setup intended to simulate the reaching of a lumbar pedicle. An experienced surgeon performed the percutaneous task wearing the HMD. System accuracy was evaluated through post-operative CT scan, measuring the maximum distance between the planned and obtained trajectories inside the pedicle canal. The mean insertion error was of 1.18 ±0.16 mm.

Basic Endovascular Skills Trainer: A surgical simulator for the training of novice practitioners of endovascular procedures.

In recent years the clinical interest for structured training in endovascular procedures has increased. Such procedures respect the physical integrity of the patient and at the same time ensure good therapeutic results. This study describes the development and testing of the B.E.S.T. (Basic Endovascular Skills Trainer) simulator. The B.E.S.T is an innovative physical endovascular simulator to learn basic skills of endovascular surgery. The simulator was tested by 25 clinicians with different levels of experience: novices, intermediates, and experts. All clinicians agree on affirming the importance of training in endovascular surgery; in particular they consider the B.E.S.T a valid simulator to learn specific basic skills of vascular surgery.