Preoperative planning and real-time assisted navigation by three-dimensional individual digital model in partial nephrectomy with three-dimensional laparoscopic system

Are 3D Image Guidance Systems Ready for Use? A Comparative Analysis of 3D Image Guidance Implementations in Minimally Invasive Partial Nephrectomy

Introduction: Three-dimensional image-guided surgical (3D-IGS) systems for minimally invasive partial nephrectomy (MIPN) can potentially improve the efficiency and accuracy of intraoperative anatomical localization and tumor resection. This review seeks to analyze the current state of research regarding 3D-IGS, including the evaluation of clinical outcomes, system functionality, and qualitative insights regarding 3D-IGS's impact on surgical procedures. Methods: We have systematically reviewed the clinical literature pertaining to 3D-IGS deployed for MIPN. For inclusion, studies must produce a patient-specific 3D anatomical model from two-dimensional imaging. Data extracted from the studies include clinical results, registration (alignment of the 3D model to the surgical scene) method used, limitations, and data types reported. A subset of studies was qualitatively analyzed through an inductive coding approach to identify major themes and subthemes across the studies. Results: Twenty-five studies were included in the review. Eight (32%) studies reported clinical results that point to 3D-IGS improving multiple surgical outcomes. Manual registration was the most utilized (48%). Soft tissue deformation was the most cited limitation among the included studies. Many studies reported qualitative statements regarding surgeon accuracy improvement, but quantitative surgeon accuracy data were not reported. During the qualitative analysis, six major themes emerged across the nine applicable studies. They are as follows: 3D-IGS is necessary, 3D-IGS improved surgical outcomes, researcher/surgeon confidence in 3D-IGS system, enhanced surgeon ability/accuracy, anatomical explanation for qualitative assessment, and claims without data or reference to support. Conclusions: Currently, clinical outcomes are the main source of quantitative data available to point to 3D-IGS's efficacy. However, the literature qualitatively suggests the benefit of accurate 3D-IGS for robotic partial nephrectomy.

Patient-specific simulations and navigation systems for partial nephrectomy

Partial nephrectomy (PN) is the standard treatment for T1 renal cell carcinoma. PN is affected more by surgical variations and requires greater surgical experience than radical nephrectomy. Patient-specific simulations and navigation systems may help to reduce the surgical experience required for PN. Recent advances in three-dimensional (3D) virtual reality (VR) imaging and 3D printing technology have allowed accurate patient-specific simulations and navigation systems. We reviewed previous studies about patient-specific simulations and navigation systems for PN. Recently, image reconstruction technology has developed, and commercial software that converts two-dimensional images into 3D images has become available. Many urologists are now able to view 3DVR images when preparing for PN. Surgical simulations based on 3DVR images can change surgical plans and improve surgical outcomes, and are useful during patient consultations. Patient-specific simulators that are capable of simulating surgical procedures, the gold-standard form of patient-specific simulations, have also been reported. Besides VR, 3D printing is also useful for understanding patient-specific information. Some studies have reported simulation and navigation systems for PN based on solid 3D models. Patient-specific simulations are a form of preoperative preparation, whereas patient-specific navigation is used intraoperatively. Navigation-assisted PN procedures using 3DVR images have become increasingly common, especially in robotic surgery. Some studies found that these systems produced improvements in surgical outcomes. Once its accuracy has been confirmed, it is hoped that this technology will spread further and become more generalized.

A three-dimensional renal tumor anatomy and intrarenal relationship nephrometry (ADDD) for robot-assisted partial nephrectomy : 3D-CT based nephrometry for RAPN

OBJECTIVE

To develop a 3D scoring system of tumor anatomy and intrarenal relationship for assessing surgical complexity and outcomes of robot-assisted partial nephrectomy (RAPN).

METHODS

We prospectively enrolled patients with a renal tumor who had a 3D model and underwent RAPN between Mar 2019 and Mar 2022. The ADDD nephrometry consisted of the contact surface area between tumor and parenchyma (A), the depth of tumor invasion into the renal parenchyma (D1), the distance from tumor to the main intrarenal artery (D2), and to the collecting system (D3). The primary outcomes included perioperative complication rate and trifecta outcome (WIT ≤ 25 min, negative surgical margins, and no major complications).

RESULTS

We enrolled a total of 301 patients. The mean tumor size was 2.93 ± 1.44 cm. There were 104 (34.6%) patients, 119 (39.5%) patients, and 78 (25.9%) patients in the low-, intermediate-, and high-risk groups, respectively. Each point increase in the ADDD score increased the risk of complications [hazard ratio (HR) 1.501]. A lower grade indicated a lower risk of failed trifecta (HR low group 15.103, intermediate group 9.258) and renal function damage (HR low risk 8.320, intermediate risk 3.165) compared to the high-risk group. The AUC of ADDD score and grade were 0.738 and 0.645 for predicting major complications, 0.766 and 0.714 for predicting trifecta outcome, and 0.746 and 0.730 for predicting postoperative renal function reservation.

CONCLUSION

The 3D-ADDD scoring system shows the tumor anatomy and its intraparenchymal relationships and has better efficacy in predicting surgical outcomes of RAPN.

Effect of augmented reality navigation technology on perioperative safety in partial nephrectomies: A meta-analysis and systematic review

Aim

To evaluate the impact of augmented reality surgical navigation (ARSN) technology on short-term outcomes of partial nephrectomy (PN).

Methods

A systematic literature search was conducted in PubMed, Embase, Cochrane, and Web of Science for eligible studies published through March 28, 2022. Two researchers independently performed the article screening, data extraction and quality review. Data analysis was performed using Cochrane Review Manager software.

Results

A total of 583 patients from eight studies were included in the analysis, with 313 in the ARSN-assisted PN group (AR group) and 270 in the conventional PN group (NAR group). ARSN-assisted PN showed better outcomes than conventional surgery in terms of operative time, estimated blood loss, global ischemia rate, warm ischemia time, and enucleation rate. However, there were no significant differences in the rate of Conversion to radical nephrectomy (RN), postoperative estimated glomerular filtration rate (eGFR), positive margin rate, and postoperative complication rate.

Conclusion

The utilization of ARSN can improve the perioperative safety of PN. Compared with conventional PN, ARSN-assisted PN can reduce intraoperative blood loss, shorten operative time, and improve renal ischemia. Although direct evidence is lacking, our results still suggest a potential advantage of ARSN in improving renal recovery after PN. However, as the ARSN system is still in an exploratory stage, its relevance in PN have been poorly reported. Additional high-quality randomized controlled trial (RCT) studies will be required to confirm the effect of ARSN on PN.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=301798, identifier PROSPERO ID: CRD42022301798.

Three-dimensional Model-assisted Minimally Invasive Partial Nephrectomy: A Systematic Review with Meta-analysis of Comparative Studies

CONTEXT

Use of three-dimensional (3D) guidance for nephron-sparing surgery (NSS) has increased in popularity, especially for laparoscopic and robotic approaches. Different 3D visualization modalities have been developed as promising new tools for surgical planning and intraoperative navigation.

OBJECTIVES

To summarize and evaluate the impact of 3D models on minimally invasive NSS in terms of perioperative, functional, and oncological outcomes.

EVIDENCE ACQUISITION

A systematic literature search was conducted in December 2021 using the Medline (PubMed), Embase (Ovid), Scopus, and Web of Science databases. The protocol was registered on PROSPERO (CRD42022300948). The search strategy used the PICOS (Population, Intervention, Comparison, Outcome, Study design) criteria and article selection was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias and the quality of the articles included were assessed. A dedicated data extraction form was used to collect the data of interest. Meta-analysis was performed using the Mantel-Haenszel method for binary outcomes, with results summarized as the odds ratio (OR), and the inverse variance method for continuous data, with results reported as the mean difference (MD). All effect estimates are reported with the 95% confidence interval (CI) and p ≤ 0.05 was considered statistically significant. All analyses were performed using R software and the meta package.

EVIDENCE SYNTHESIS

The initial electronic search identified 450 papers, of which 17 met the inclusion criteria and were included in the analysis. Use of 3D technology led to a significant reduction in the global ischemia rate (OR 0.22, 95% CI 0.07-0.76; p = 0.02) and facilitated more frequent enucleation (OR 2.54, 95% CI 1.36-4.74; p < 0.01) and less frequent opening of the collecting system (OR 0.36, 95% CI 0.15-0.89; p = 0.03) and was associated with less blood loss (MD 23.1 ml, 95% CI 31.8-14.4; p < 0.01). 3D guidance for NSS was associated with a significant reduction in the transfusion rate (OR 0.20, 95% CI 0.07-0.56; p < 0.01). There were no significant differences in rates of conversion to radical nephrectomy, minor and major complications, change in glomerular filtration rate, or surgical margins (all p > 0.05).

CONCLUSIONS

3D guidance for NSS is associated with lower rates of detriment and surgical injury to the kidney. Specifically, a lower amount of nontumor renal parenchyma is exposed to ischemia or sacrificed during resection, and opening of the collecting system is less frequent. However, use of 3D technology does not lead to significant improvements in oncological or functional outcomes.

PATIENT SUMMARY

We reviewed the use of three-dimensional tools for minimally invasive surgery for partial removal of the kidney in patients with kidney cancer. The evidence suggests that these tools have benefits during surgery, but do not lead to significant improvements in cancer control or functional outcomes for patients.

Systematic Review of Comparative Studies of 3D Models for Preoperative Planning in Minimally Invasive Partial Nephrectomy

Background: The employment of 3-dimensional (3D) virtual models of the organs and tumors, obtained from conventional 2-dimensional (2D) imaging (i.e. computed tomography scan and magnetic resonance imaging) have already demonstrated an outstanding potential in urology, especially in renal surgery. Objectives: The aim of this systematic review is to provide an updated focus on the results obtained from the preoperative employment of 3D virtual imaging reconstructions in nephron sparing oncological surgery. Methods: A systematic literature search was conducted in April 2022 using Medline (via PubMed), Embase (via Ovid), Scopus, and Web of Science. The search strategy used PICO criteria and article selection was conducted in accordance with the PRISMA guidelines. The risk of bias and the quality of the articles included were assessed. A dedicated data extraction form was used to collect the data of interest. Results: The initial electronic search identified 471 papers, of which 13 ultimately met the inclusion criteria and were included in the review. 11 studies reported outcomes of virtual models, 2 studies focused on printed 3D models. In these studies, the application of 3D models for preoperative planning has been reported to increase the selective clamping rate and reducing the opening of collecting system, blood loss and loss of renal function. Conclusions: 3D virtual models seem to provide some surgical benefits for preoperative planning especially for complex renal masses. In the next future the continuous evolution of this technology may further increase its field of application and its potential clinical benefit.

The application of full-size three-dimensional individual printed model combined with three-dimensional digital demonstration can facilitate patient's preoperative comprehension to robotic-assisted laparoscopic partial nephrectomy

BACKGROUND

In this study, it was aimed to evaluate the feasibility and effectiveness of full-size three-dimensional individual printed model (3D-IPM) based on computerized tomography (CT) reconstruction combined with 3D individual digital models (3D-IDMs) for improving the patient's and their families' comprehension levels of robotic-assisted laparoscopic partial nephrectomy (RALPN) preoperatively.

METHODS

Between January 2020 and January 2021, 37 patients underwent RALPN in our institution. 3D individual digital models (3D-IDMs) were reconstructed based on the data of computerized tomography (CT) scanning and full-size 3D-IPMs were fabricated correspondingly. For each patient and his/her closest accompanying immediate family member (CAIFM) (spouse or son/daughter), two semi-structured conversations were held by using CT films (1st conversation) and 3D-IPM combined with 3D-IDM demonstration (2nd one) respectively. The preoperative levels of comprehension were evaluated quantitatively by using a self-made preoperative comprehending score (PCS) in the patients and CAIFMs.

RESULTS

All the fabrications of full-size 3D-IPMs and all the operations were technically successful. The total PCS elevated significantly by presenting 3D-IPM combined with 3D-IDM demonstration compared with CT films (42.5 vs 35.5 in patients, P < 0.001; 42.9 vs 35.8 in CAIFMs, P < 0.001). Sub-PCSs in the evaluating aspects of renal anatomy, mass characteristics, the upcoming RALPN procedure, potential complication risks, and prognosis also showed a uniformed climbing pattern with the assistance of 3D-IPM+3D-IDM.

CONCLUSION

The application of 3D-IPM presentation combined with 3D-IDM demonstration can improve the preoperative comprehension of patient and CAIFM to RALPN with more direct-viewing and verisimilar presentation, and can be used in RALPN patient education for increasing patients' and their families' cognitive empowerment.

Three-dimensional virtual planning for nodule resection in solid organs: A systematic review and meta-analysis

OBJECTIVES

To systematically review the effects of 3D-imaging virtual planning for nodule resection in the following solid organs: lung, liver, and kidney.

METHODS

MEDLINE, EMBASE, and Cochrane Library were searched through September 31, 2020 to include randomized and non-randomized controlled studies that compared outcomes of surgical resection of lung, liver, or kidney nodule resection with and without 3D virtual planning with computed tomography. From each article, the mean operation time (OT), mean estimated blood loss (EBL), mean postoperative hospital stay (POHS), and the number of postoperative events (POE) were extracted. The effect size (ES) of 3D virtual planning vs. non-3D planning was extracted from each study to calculate the pooled measurements for continuous variables (OT, EBL, POHS). Data were pooled using a random-effects model.

RESULTS

The literature search yielded 2397 studies and 10 met the inclusion criteria with a total of 897 patients. There was a significant difference in OT between groups with a moderate ES favoring the 3D group (ES,-0.56; 95%CI: 0.91,-0.29; I² = 83.1%; p < .001). Regarding EBL, there was a significant difference between 3D and non-3D with a small ES favoring IGS (ES,-0.18; 95%CI: 0.33,-0.02; I² = 22.5%; p = .0236). There was no difference between the 3D and non-3D groups for both POHS (POHS ES,-0.15; 95%CI: 0.39,0.10; I² = 37.0%; p = .174) and POE (POE odds ratio (OR),0.80; 95%CI:0.54,1.19; I² = 0.0%; p = .0.973).

CONCLUSIONS

3D-imaging planning for surgical resection of lung, kidney, and liver nodules could reduce OT and EBL with no effects on immediate POHS and POE. Improvements in these perioperative variables could improve medium and long-term postoperative clinical outcomes.

Surgical Tracking, Registration, and Navigation Characterization for Image-guided Renal Interventions

Most image-guided interventions rely on surgical tracking and image/model to patient registration to establish a spatial relationship between the patient and the pre- and intraprocedural images, by using surgical tracking and localization systems. In this work, we characterize the tracking, registration and navigation accuracy using two different surgical localization systems - the NDI Polaris Spectra optical tracking system and the NDI Aurora electromagnetic tracking system - in the context of an image-guided renal intervention, using a 3D printed life-size model of a patient-specific kidney phantom generated from a CT image. Our results reported a 0.05 mm fiducial localization error, 0.70 mm fiducial registration error, and 0.78 mm target registration error, and 0.63 mm overall navigation error using the optical tracking, and 0.12 mm fiducial localization error, 0.78 mm fiducial registration error, 0.93 mm target registration error and 0.89 mm overall navigation error using electromagnetic tracking. Additionally, our study also showed similarity between the overall navigation accuracy using optical (0.63 mm RMS error) or electromagnetic tracking (0.89 mm RMS error) and the overall navigation accuracy achieved using direct visualization of the surgical scene (0.68 mm and 1.06 RMS error respectively), which serves as a baseline control metric.

Three-dimensional printing - Assisted planning for complete and safe resection of retroperitoneal tumor

BACKGROUND

Surgery is usually recommended to treat retroperitoneal tumors. However, complete surgical resections often remain challenging.

OBJECTIVE

To assess the assistant role of three-dimensional (3D) imaging and printing model in retroperitoneal tumor resection, as well as compare the difference between 3D printing and computed tomography (CT) in preoperative planning and confidence building.

METHODS

We admitted a patient with retroperitoneal mass (13.0×6.4×14.8 cm) adjacent to important abdominal blood vessels whose surgery was thought to be difficult. 3D printing and CT was arranged. A novel questionnaire and scoring system consisting of surgery difficulty and safety were designed to compare doctors understanding and confidence for surgery based on 3D printing and CT. Twenty-four doctors completed the scoring table based on CT and then 3D imaging, respectively. Paired t-test was applied for statistics analysis.

RESULTS

Preoperative evaluation based on 3D printing indicated that the tumor could be removed completely. The operation lasted 120 minutes to successfully remove the tumor and the estimated blood loss was less than 100 ml. Scores based on 3D printing is significantly higher than CT in difficulty and safety of surgery (p < 0.001). Interestingly, the junior doctors seem to benefit more from 3D printing than the senior doctors.

CONCLUSIONS

3D imaging and printing model provides greater help for preoperative planning and confidence building than using CT in resection of retroperitoneal tumor, especially for the junior doctors.

Computer-assisted surgery: virtual- and augmented-reality displays for navigation during urological interventions

PURPOSE OF REVIEW

To provide an overview of the developments made for virtual- and augmented-reality navigation procedures in urological interventions/surgery.

RECENT FINDINGS

Navigation efforts have demonstrated potential in the field of urology by supporting guidance for various disorders. The navigation approaches differ between the individual indications, but seem interchangeable to a certain extent. An increasing number of pre- and intra-operative imaging modalities has been used to create detailed surgical roadmaps, namely: (cone-beam) computed tomography, MRI, ultrasound, and single-photon emission computed tomography. Registration of these surgical roadmaps with the real-life surgical view has occurred in different forms (e.g. electromagnetic, mechanical, vision, or near-infrared optical-based), whereby the combination of approaches was suggested to provide superior outcome. Soft-tissue deformations demand the use of confirmatory interventional (imaging) modalities. This has resulted in the introduction of new intraoperative modalities such as drop-in US, transurethral US, (drop-in) gamma probes and fluorescence cameras. These noninvasive modalities provide an alternative to invasive technologies that expose the patients to X-ray doses. Whereas some reports have indicated navigation setups provide equal or better results than conventional approaches, most trials have been performed in relatively small patient groups and clear follow-up data are missing.

SUMMARY

The reported computer-assisted surgery research concepts provide a glimpse in to the future application of navigation technologies in the field of urology.

How well do software assistants for minimally invasive partial nephrectomy meet surgeon information needs? A cognitive task analysis and literature review study

INTRODUCTION

Intraoperative software assistance is gaining increasing importance in laparoscopic and robot-assisted surgery. Within the user-centred development process of such systems, the first question to be asked is: What information does the surgeon need and when does he or she need it? In this article, we present an approach to investigate these surgeon information needs for minimally invasive partial nephrectomy and compare these needs to the relevant surgical computer assistance literature.

MATERIALS AND METHODS

First, we conducted a literature-based hierarchical task analysis of the surgical procedure. This task analysis was taken as a basis for a qualitative in-depth interview study with nine experienced surgical urologists. The study employed a cognitive task analysis method to elicit surgeons' information needs during minimally invasive partial nephrectomy. Finally, a systematic literature search was conducted to review proposed software assistance solutions for minimally invasive partial nephrectomy. The review focused on what information the solutions present to the surgeon and what phase of the surgery they aim to support.

RESULTS

The task analysis yielded a workflow description for minimally invasive partial nephrectomy. During the subsequent interview study, we identified three challenging phases of the procedure, which may particularly benefit from software assistance. These phases are I. Hilar and vascular management, II. Tumour excision, and III. Repair of the renal defects. Between these phases, 25 individual challenges were found which define the surgeon information needs. The literature review identified 34 relevant publications, all of which aim to support the surgeon in hilar and vascular management (phase I) or tumour excision (phase II).

CONCLUSION

The work presented in this article identified unmet surgeon information needs in minimally invasive partial nephrectomy. Namely, our results suggest that future solutions should address the repair of renal defects (phase III) or put more focus on the renal collecting system as a critical anatomical structure.

Retrolaparoscopic adrenalectomy assisted by three-dimensional reconstructed digital model in a patient with situs inversus totalis

Background

Situs inversus totalis is a relatively rare congenital anomaly. Performing the retrolaparoscopic adrenalectomy for the patient with situs inversus totalis is a skill-demanding and challenging surgical task, which has been even more rarely reported.

Case presentation

We present a case with a large right adrenal mass (10.2 × 9.4 × 7.9 cm) complicated by situs inversus totalis. This 59-year-old female patient underwent the retrolaparoscopic adrenalectomy in our department. In order to facilitate the surgical orientation and improve the manipulating accuracy, the data from computed tomography images was extracted and the three-dimensional digital model was reconstructed. Under the assistance of preoperative planning and intraoperative navigation by the three-dimensional digital model, the retrolaparoscopic adrenalectomy was technically precise and successful. The targeted adrenal tumor was excised completely with final pathological diagnosis of adrenocortical adenoma.

Conclusions

Retrolaparoscopic adrenalectomy can be performed safely in patients with situs inversus totalis. The assistance of preoperative planning and intraoperative navigation by the reconstructed three-dimensional digital model can facilitate the operation and lead to more precise vessel manipulation and accurate excision of tumor that is both effective and safe.

Electronic supplementary material

The online version of this article (10.1186/s12957-018-1473-8) contains supplementary material, which is available to authorized users.

Virtual and Augmented Reality Systems for Renal Interventions: A Systematic Review

PURPOSE

Many virtual and augmented reality systems have been proposed to support renal interventions. This paper reviews such systems employed in the treatment of renal cell carcinoma and renal stones.

METHODS

A systematic literature search was performed. Inclusion criteria were virtual and augmented reality systems for radical or partial nephrectomy and renal stone treatment, excluding systems solely developed or evaluated for training purposes.

RESULTS

In total, 52 research papers were identified and analyzed. Most of the identified literature (87%) deals with systems for renal cell carcinoma treatment. About 44% of the systems have already been employed in clinical practice, but only 20% in studies with ten or more patients. Main challenges remaining for future research include the consideration of organ movement and deformation, human factor issues, and the conduction of large clinical studies.

CONCLUSION

Augmented and virtual reality systems have the potential to improve safety and outcomes of renal interventions. In the last ten years, many technical advances have led to more sophisticated systems, which are already applied in clinical practice. Further research is required to cope with current limitations of virtual and augmented reality assistance in clinical environments.

Application of Three-Dimensional Visualization Technology in Laparoscopic Partial Nephrectomy of Renal Tumor: A Comparative Study

PURPOSE

To compare the effectiveness and safety of individualized three-dimensional visualization technology (3DVT) on surgical planning and perioperative outcomes in laparoscopic partial nephrectomy (LPN) for renal cell carcinoma (RCC) with routine computed tomography (CT) examination in the treatment of renal tumor.

METHODS

From May 2015 to March 2016, a total of 94 patients with cT1 RCC who underwent surgical treatment in our department were analyzed retrospectively. Among these patients, a total of 49 cases received LPN with operation plan based on 3DVT. Surgical plan was obtained by virtual operation and morphometry on 3D reconstruction model. The remaining 45 cases received surgical treatment with traditional CT examination. Patient demographic, surgical outcome, and postoperative parameters were compared between these two groups.

RESULTS

No significant difference was found in blood loss volume, postoperative complication, selective clamping success rate, changes in postoperative renal function, and operative and ischemic time between the two groups. However, when handling complicated tumor with R.E.N.A.L score ≥8, operation time (126.7 ± 36.4 versus 154.8 ± 34.7, P = .018) and occurrence of postoperative urinary leak (0 versus 4, 0% versus 22.2%, P = .033) were diminished significantly in the 3DVT group.

CONCLUSIONS

3DVT provided precise information of anatomical structure in the operative area and reliable guidance for preoperative plan design. Our results indicated that 3DVT facilitated accurate visible image-guided tumor resection with ideal renal function preservation in LPN for renal tumor of high complexity.

Robust augmented reality registration method for localization of solid organs' tumors using CT-derived virtual biomechanical model and fluorescent fiducials

BACKGROUND

Augmented reality (AR) is the fusion of computer-generated and real-time images. AR can be used in surgery as a navigation tool, by creating a patient-specific virtual model through 3D software manipulation of DICOM imaging (e.g., CT scan). The virtual model can be superimposed to real-time images enabling transparency visualization of internal anatomy and accurate localization of tumors. However, the 3D model is rigid and does not take into account inner structures' deformations. We present a concept of automated AR registration, while the organs undergo deformation during surgical manipulation, based on finite element modeling (FEM) coupled with optical imaging of fluorescent surface fiducials.

METHODS

Two 10 × 1 mm wires (pseudo-tumors) and six 10 × 0.9 mm fluorescent fiducials were placed in ex vivo porcine kidneys (n = 10). Biomechanical FEM-based models were generated from CT scan. Kidneys were deformed and the shape changes were identified by tracking the fiducials, using a near-infrared optical system. The changes were registered automatically with the virtual model, which was deformed accordingly. Accuracy of prediction of pseudo-tumors' location was evaluated with a CT scan in the deformed status (ground truth). In vivo: fluorescent fiducials were inserted under ultrasound guidance in the kidney of one pig, followed by a CT scan. The FEM-based virtual model was superimposed on laparoscopic images by automatic registration of the fiducials.

RESULTS

Biomechanical models were successfully generated and accurately superimposed on optical images. The mean measured distance between the estimated tumor by biomechanical propagation and the scanned tumor (ground truth) was 0.84 ± 0.42 mm. All fiducials were successfully placed in in vivo kidney and well visualized in near-infrared mode enabling accurate automatic registration of the virtual model on the laparoscopic images.

CONCLUSIONS

Our preliminary experiments showed the potential of a biomechanical model with fluorescent fiducials to propagate the deformation of solid organs' surface to their inner structures including tumors with good accuracy and automatized robust tracking.

Application of Virtual, Augmented, and Mixed Reality to Urology

Recent developments in virtual, augmented, and mixed reality have introduced a considerable number of new devices into the consumer market. This momentum is also affecting the medical and health care sector. Although many of the theoretical and practical foundations of virtual reality (VR) were already researched and experienced in the 1980s, the vastly improved features of displays, sensors, interactivity, and computing power currently available in devices offer a new field of applications to the medical sector and also to urology in particular. The purpose of this review article is to review the extent to which VR technology has already influenced certain aspects of medicine, the applications that are currently in use in urology, and the future development trends that could be expected.

Computer-assisted surgical planning and intraoperative guidance in fetal surgery: a systematic review

Fetal surgery has become a clinical reality, with interventions for twin‐to‐twin transfusion syndrome (TTTS) and spina bifida demonstrated to improve outcome. Fetal imaging is evolving, with the use of 3D ultrasound and fetal MRI becoming more common in clinical practise. Medical imaging analysis is also changing, with technology being developed to assist surgeons by creating 3D virtual models that improve understanding of complex anatomy, and prove powerful tools in surgical planning and intraoperative guidance.

We introduce the concept of computer‐assisted surgical planning, and present the results of a systematic review of image reconstruction for fetal surgical planning that identified six articles using such technology.

Indications from other specialities suggest a benefit of surgical planning and guidance to improve outcomes. There is therefore an urgent need to develop fetal‐specific technology in order to improve fetal surgical outcome. © 2015 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.

What's already known about this topic?

Fetal surgery has now become a clinical reality, with interventions such as laser treatment for twin‐to‐twin transfusion syndrome (TTTS) and open fetal surgery for spina bifida demonstrated in randomised control trials to improve neonatal outcome

Other specialities are increasingly utilising computer‐assisted surgical planning software, with evidence that this can improve outcome

What does this study add?

We feel that there is an urgent need to develop fetal‐specific technology for surgical planning as it is likely to play an important role in improving outcomes from fetal surgery