Computer-assisted navigation in oral and maxillofacial surgery: A systematic review

Background

The term "navigation" describes a device that can pinpoint critical anatomical features, the most direct path to the target, and the optimal surgical orientation. This study aimed to conduct a comprehensive literature search on computer-assisted navigation for use in oral and maxillofacial surgery.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, relevant studies were retrieved from five electronic databases: Medline, Web of Science, PubMed, Google Scholar, and Saudi Digital Library (SDL). The central question was, "Does the computer-assisted navigation system improve the outcome of surgical procedures in the oral and maxillofacial region?" The Cochrane Risk of Bias 2 was used to determine the various types of bias.

Results

Post-traumatic midfacial reconstruction is one of the many fields that have benefited from the use of computer-assisted navigation because of its reliability. It can also be used to extricate difficult foreign entities from the operative zone. Locating critical anatomical components, communicating the surgical plan to the patient, and verifying surgical success can improve the function and appearance of patients with dentofacial abnormalities. In addition, it decreases the surgical error margin and duration.

Conclusion

Computer-assisted navigation is promising in surgical practice. The accuracy of surgery can be significantly enhanced by first planning the process in a virtual environment and then performing it under close supervision in real time. In addition, the time required for preoperative planning and surgery can be reduced by creating and improving software programs.

A novel Foley catheter made of high-intensity near-infrared fluorescent silicone rubber for image-guided surgery of lower rectal cancer

BACKGROUND

Urethral injury occurs in 1-6 % of male cases during minimally invasive surgery of lower rectal cancer. A Foley catheter emitting near-infrared (NIR) fluorescence of sufficient intensity has been expected to locate the urethra during image-guided surgery. Although it has been difficult to impart NIR fluorescent properties to biocompatible thermosetting polymers, we have recently succeeded in developing a NIR fluorescent compound for silicone rubber and a NIR fluorescent Foley catheter (HICARL). Here, we evaluated its NIR fluorescence properties and visibility performance using porcine anorectal isolation specimens.

METHODS

The HICARL catheter was made of a mixture of solid silicone rubber and a NIR fluorescent compound that emits fluorescence with a wavelength of 820-880 nm, while a conventional transparent Foley catheter was made of solid silicone rubber only. As a standard for comparison of the intensity of NIR fluorescence, a transparent Foley catheter the lumen of which was filled with a mixture of indocyanine green (ICG) and human plasma was used. As a comparison to assess the visibility performance of the HICARL catheter, a transparent Foley catheter into which a commercially available NIR fluorescent polyurethane ureteral catheter (NIRC) was placed was used.

RESULTS

A NIR fluorescence quantitative imaging analysis revealed that the Foley-NIRC catheter and the HICARL catheter emitted 3.42 ± 0.42 and 6.43 ± 0.07 times more fluorescence than the Foley-ICG catheter, respectively. The location of the HICARL catheter placed in the anorectum with a wall thickness of 3.8 ± 0.1 mm was clearly delineated in its entirety by NIR fluorescence, while that of the Foley-NIRC catheter was faintly or only partially visible.

CONCLUSIONS

The HICARL catheter emitting NIR fluorescence of sufficient intensity is a promising and easy-to-use tool for urethral visualization during image-guided surgery of lower rectal cancer.

Surgical radioguidance with beta-emitting radionuclides; challenges and possibilities: A position paper by the EANM

Radioguidance that makes use of β-emitting radionuclides is gaining in popularity and could have potential to strengthen the range of existing radioguidance techniques. While there is a strong tendency to develop new PET radiotracers, due to favorable imaging characteristics and the success of theranostics research, there are practical challenges that need to be overcome when considering use of β-emitters for surgical radioguidance. In this position paper, the EANM identifies the possibilities and challenges that relate to the successful implementation of β-emitters in surgical guidance, covering aspects related to instrumentation, radiation protection, and modes of implementation.

Precise tumor delineation in clinical tissues using a novel acidic tumor microenvironment activatable near-infrared fluorescent contrast agent

Tumor selective near-infrared (NIR) fluorescent contrast agents has the potential to greatly enhance the efficiency and precision of tumor surgery by enabling real-time tumor margin identification for tumor resection guided by imaging. However, the development of these agents is still challenging. In this study, based on the acidic tumor microenvironment (TME), we designed and synthesized a novel pH-sensitive NIR fluorescent contrast agent OBD from β-carboline. The fluorescence quantum yield of OBD exhibited a notable increase at pH 3.6, approximately 12-fold higher compared to its value at pH 7.4. After cellular uptake, OBD lighted up the cancer cells with high specificity and accumulated in the mitochondria. Spraying OBD emitted selective fluorescence in xenograft tumor tissues with tumor-to-normal tissue ratios (TNR) as high as 11.18, implying successful image-guided surgery. Furthermore, OBD was also shown to track metastasis in spray mode. After simple topical spray, OBD rapidly and precisely visualized the tumor margins of clinical colon and liver tissues with TNR over 4.2. Therefore, the small-molecule fluorescent contrast agent OBD has promising clinical applications in tumor identification during surgery.

Patient-specific profile guide in rhinoplasty

The introduction of new technologies in the field of facial aesthetic surgery is leading to improvement in surgical intervention quality. In the field of rhinoplasty, the design of customized surgical guides for the patient helps to perform an intervention with greater precision according to the presurgical planning. We present our design and method of fabrication of surgical profile guides for patients undergoing rhinoplasty, with free software and mostly in-house design and fabrication. The entire design process takes less than an hour. We have found that designing the guide enhances the communication process with the patient, and using that guide improves the surgical result.

Automatic rigid image Fusion of preoperative MR and intraoperative US acquired after craniotomy

BACKGROUND

Neuronavigation of preoperative MRI is limited by several errors. Intraoperative ultrasound (iUS) with navigated probes that provide automatic superposition of pre-operative MRI and iUS and three-dimensional iUS reconstruction may overcome some of these limitations. Aim of the present study is to verify the accuracy of an automatic MRI - iUS fusion algorithm to improve MR-based neuronavigation accuracy.

METHODS

An algorithm using Linear Correlation of Linear Combination (LC2)-based similarity metric has been retrospectively evaluated for twelve datasets acquired in patients with brain tumor. A series of landmarks were defined both in MRI and iUS scans. The Target Registration Error (TRE) was determined for each pair of landmarks before and after the automatic Rigid Image Fusion (RIF). The algorithm has been tested on two conditions of the initial image alignment: registration-based fusion (RBF), as given by the navigated ultrasound probe, and different simulated course alignments during convergence test.

RESULTS

Except for one case RIF was successfully applied in all patients considering the RBF as initial alignment. Here, mean TRE after RBF was significantly reduced from 4.03 (± 1.40) mm to (2.08 ± 0.96 mm) (p = 0.002), after RIF. For convergence test, the mean TRE value after initial perturbations was 8.82 (± 0.23) mm which has been reduced to a mean TRE of 2.64 (± 1.20) mm after RIF (p < 0.001).

CONCLUSIONS

The integration of an automatic image fusion method for co-registration of pre-operative MRI and iUS data may improve the accuracy in MR-based neuronavigation.

Image Guided Endoscopic Sinus Surgery: First Experience from Kashmir Valley

Image guidance is best suited to paranasal sinus surgeries as these demand a high degree of anatomical precision because of close proximity to orbit and cranial cavity which at times is challenging in patients with frequent anatomical variations. This study is aimed to describe our first experience of using image guided endoscopic sinus surgery in Kashmir valley in terms of real time correlation between the operative field and the preoperative imaging; to evaluate its utility in disease clearance and to evaluate patient reported outcome measures using (pre and post-op) VAS, SNOT-22, Lund Mackey endoscopic and radiological scores. This prospective observational study was conducted from September 2016 to August 2018. Patients with the specific inclusion and exclusion criteria were operated using image guidance system. Pre and post operative SNOT-22, VAS, Lund Mackey endoscopic and radiological scoring were compared. Operative time, Instrument accuracy and complications were noted. Out of twenty cases enrolled in this study majority (14) patients (70%) were cases of uncomplicated chronic rhinosinusitis with nasal polyposis. Mean number of sinuses operated were 7.8 ± 2.14. Set up time for installing navigation system in first 10 cases was on an average 17 ± 1.67 min and in second 10 cases it was 12 ± 1.42 min. Mean operative time recorded was 112 ± 17.32 min. Accuracy of our system was 1.25 ± 0.73 mm (0.50-1.80) and average blood loss was 100 ± 23.54 ml. There was statistically significant reduction in postoperative VAS score, SNOT-22 score, Lund Mackey endoscopic and radiological scoring. Revision FESS was done in 12 cases and most common intraoperative absent nasal landmark was middle turbinate in these cases. No orbital or intracranial complication was seen. Minor complications were seen. Image guided surgery is a valuable tool worth use in difficult and revision cases. It makes the surgeon comfortable and saves patient from any major complication.

Navigation Assisted Frontal Sinus Osteoplastic Flap Surgeries - A Case Series

Osteoplastic flap surgery of the frontal sinus is still a relevant surgical technique for frontal sinus pathologies despite advancements in endoscopic techniques due to the complex anatomy of frontal sinus and limitations of endoscopic techniques for certain pathologies. The most crucial step in this surgery is accurate delineation of the frontal sinus pneumatisation which guides the osteotomies and this is conventionally done with radiographs which is not without errors. Here we present three cases where we have utilized image guidance technology for osteoplastic flap surgery of the frontal sinus with superior results.

Navigated liver surgery: State of the art and future perspectives

BACKGROUND

In recent years, the development of digital imaging technology has had a significant influence in liver surgery. The ability to obtain a 3-dimensional (3D) visualization of the liver anatomy has provided surgery with virtual reality of simulation 3D computer models, 3D printing models and more recently holograms and augmented reality (when virtual reality knowledge is superimposed onto reality). In addition, the utilization of real-time fluorescent imaging techniques based on indocyanine green (ICG) uptake allows clinicians to precisely delineate the liver anatomy and/or tumors within the parenchyma, applying the knowledge obtained preoperatively through digital imaging. The combination of both has transformed the abstract thinking until now based on 2D imaging into a 3D preoperative conception (virtual reality), enhanced with real-time visualization of the fluorescent liver structures, effectively facilitating intraoperative navigated liver surgery (augmented reality).

DATA SOURCES

A literature search was performed from inception until January 2021 in MEDLINE (PubMed), Embase, Cochrane library and database for systematic reviews (CDSR), Google Scholar, and National Institute for Health and Clinical Excellence (NICE) databases.

RESULTS

Fifty-one pertinent articles were retrieved and included. The different types of digital imaging technologies and the real-time navigated liver surgery were estimated and compared.

CONCLUSIONS

ICG fluorescent imaging techniques can contribute essentially to the real-time definition of liver segments; as a result, precise hepatic resection can be guided by the presence of fluorescence. Furthermore, 3D models can help essentially to further advancing of precision in hepatic surgery by permitting estimation of liver volume and functional liver remnant, delineation of resection lines along the liver segments and evaluation of tumor margins. In liver transplantation and especially in living donor liver transplantation (LDLT), 3D printed models of the donor's liver and models of the recipient's hilar anatomy can contribute further to improving the results. In particular, pediatric LDLT abdominal cavity models can help to manage the largest challenge of this procedure, namely large-for-size syndrome.

Clinical use of augmented reality, mixed reality, three-dimensional-navigation and artificial intelligence in liver surgery

A precise knowledge of intra-parenchymal vascular and biliary architecture and the location of lesions in relation to the complex anatomy is indispensable to perform liver surgery. Therefore, virtual three-dimensional (3D)-reconstruction models from computed tomography/magnetic resonance imaging scans of the liver might be helpful for visualization. Augmented reality, mixed reality and 3D-navigation could transfer such 3D-image data directly into the operation theater to support the surgeon. This review examines the literature about the clinical and intraoperative use of these image guidance techniques in liver surgery and provides the reader with the opportunity to learn about these techniques. Augmented reality and mixed reality have been shown to be feasible for the use in open and minimally invasive liver surgery. 3D-navigation facilitated targeting of intraparenchymal lesions. The existing data is limited to small cohorts and description about technical details e.g., accordance between the virtual 3D-model and the real liver anatomy. Randomized controlled trials regarding clinical data or oncological outcome are not available. Up to now there is no intraoperative application of artificial intelligence in liver surgery. The usability of all these sophisticated image guidance tools has still not reached the grade of immersion which would be necessary for a widespread use in the daily surgical routine. Although there are many challenges, augmented reality, mixed reality, 3D-navigation and artificial intelligence are emerging fields in hepato-biliary surgery.

Performance of image guided navigation in laparoscopic liver surgery - A systematic review

BACKGROUND

Compared to open surgery, minimally invasive liver resection has improved short term outcomes. It is however technically more challenging. Navigated image guidance systems (IGS) are being developed to overcome these challenges. The aim of this systematic review is to provide an overview of their current capabilities and limitations.

METHODS

Medline, Embase and Cochrane databases were searched using free text terms and corresponding controlled vocabulary. Titles and abstracts of retrieved articles were screened for inclusion criteria. Due to the heterogeneity of the retrieved data it was not possible to conduct a meta-analysis. Therefore results are presented in tabulated and narrative format.

RESULTS

Out of 2015 articles, 17 pre-clinical and 33 clinical papers met inclusion criteria. Data from 24 articles that reported on accuracy indicates that in recent years navigation accuracy has been in the range of 8-15 mm. Due to discrepancies in evaluation methods it is difficult to compare accuracy metrics between different systems. Surgeon feedback suggests that current state of the art IGS may be useful as a supplementary navigation tool, especially in small liver lesions that are difficult to locate. They are however not able to reliably localise all relevant anatomical structures. Only one article investigated IGS impact on clinical outcomes.

CONCLUSIONS

Further improvements in navigation accuracy are needed to enable reliable visualisation of tumour margins with the precision required for oncological resections. To enhance comparability between different IGS it is crucial to find a consensus on the assessment of navigation accuracy as a minimum reporting standard.

Quantitative fluorescence angiography aids novice and experienced surgeons in performing intestinal resection in well-perfused tissue

Background

Anastomotic leakage (AL) after gastrointestinal resection is a devastating complication with huge consequences for the patient. As AL is associated with poor blood supply, tools for objective assessment of perfusion are in high demand. Indocyanine green angiography (ICG-FA) and quantitative analysis of ICG-FA (q-ICG) seem promising. This study aimed to investigate whether ICG-FA and q-ICG could improve perfusion assessment performed by surgeons of different experience levels.

Methods

Thirteen small bowel segments with a varying degree of devascularization, including two healthy sham segments, were constructed in a porcine model. We recruited students, residents, and surgeons to perform perfusion assessment of the segments in white light (WL), with ICG-FA, and after q-ICG, all blinded to the degree of devascularization.

Results

Forty-five participants fulfilled the study (18 novices, 12 intermediates, and 15 experienced). ICG and q-ICG helped the novices correctly detect the healthy bowel segments to experienced surgeons’ level. ICG and q-ICG also helped novice surgeons to perform safer resections in healthy tissue compared with normal WL. The relative risk (RR) of leaving ischemic tissue in WL and ICG compared with q-ICG, even for experienced surgeons was substantial, intermediates (RR = 8.9, CI95% [4.0;20] and RR = 6.2, CI95% [2.7;14.1]), and experienced (RR = 4.7, CI95% [2.6;8.7] and RR = 4.0, CI95% [2.1;7.5]).

Conclusion

Q-ICG seems to guide surgeons, regardless of experience level, to safely perform resection in healthy tissue, compared with standard WL. Future research should focus on this novel tool’s clinical impact.

A multimodal molecular imaging approach targeting urokinase plasminogen activator receptor for the diagnosis, resection and surveillance of urothelial cell carcinoma

With a 5-year recurrence rate of 30-78%, urothelial cell carcinoma (UCC) rates amongst the highest of all solid malignancies. Consequently, after transurethral resection, patients are subjugated to life-long endoscopic surveillance. A multimodal near-infrared (NIR) fluorescence-based imaging strategy can improve diagnosis, resection and surveillance, hence increasing quality of life.

METHODS

Expression of urokinase plasminogen activator receptor (uPAR) and epithelial cell adhesion molecule (EpCAM) are determined on paraffin-embedded human UCC using immunohistochemistry and on UCC cell lines by flow cytometry. MNPR-101, a humanised monoclonal antibody targeting uPAR is conjugated to IRDye800CW and binding is validated in vitro using surface plasmon resonance and cell-based binding assays. In vivo NIR fluorescence and photoacoustic three-dimensional (3D) imaging are performed with subcutaneously growing human UM-UC-3luc2 cells in BALB/c-nude mice. The translational potential is confirmed in a metastasising UM-UC-3luc2 orthotopic mouse model. Infliximab-IRDye800CW and rituximab-IRDye800CW are used as controls.

RESULTS

UCCs show prominent uPAR expression at the tumour-stroma interface and EpCAM on epithelial cells. uPAR and EpCAM are expressed by 6/7 and 4/7 UCC cell lines, respectively. In vitro, MNPR-101-IRDye800CW has a picomolar affinity for domain 2-3 of uPAR. In vivo fluorescence imaging with MNPR-101-IRDye800CW, specifically delineates both subcutaneous and orthotopic tumours with tumour-to-background ratios reaching as high as 6.8, differing significantly from controls (p < 0.0001). Photoacoustic 3D in depth imaging confirms the homogenous distribution of MNPR-101-IRDye800CW through the tumour.

CONCLUSIONS

MNPR-101-IRDye800CW is suitable for multimodal imaging of UCC, awaiting clinical translation.

Virus-Mimicking Nanoparticles for Targeted Near Infrared Fluorescence Imaging of Intraperitoneal Ovarian Tumors in Mice

Ovarian cancer is the most lethal malignancy affecting the female reproductive system. Identification and removal of all ovarian intraperitoneal tumor deposits during the intraoperative surgery is important towards preventing cancer recurrence and ultimately improving patient survival. Herein, we investigate the effectiveness of virus mimicking nanoparticles, derived from genome-depleted plant-infecting brome mosaic virus, and doped with near infrared (NIR) brominated cyanine dye BrCy106-NHS, for targeted NIR fluorescence imaging of intraperitoneal ovarian tumors. We refer to these nanoparticles as optical viral ghosts (OVGs). We functionalized the OVGs with antibodies against HER2 receptor, a biomarker over-expressed in ovarian cancers. We injected functionalized OVGs, non-functionalized OVGs, and non-encapsulated BrCy106-NHS intravenously in mice implanted with ovarian intraperitoneal tumors. Tumors were extracted at 2, 6, and 24 h post-injection, and quantitatively analyzed using NIR fluorescence imaging. Fluorescence emission from tumors associated with the injection of the functionalized OVGs continued to increase between 2 and 24 h post-injection. At 24 h timepoint, the average spectrally-integrated fluorescence emission from homogenized tumors containing functionalized-OVGs was about 3.5 and 19.5 times higher than those containing non-functionalized OVGs or non-encapsulated BrCy106-NHS, respectively. Similarly, by using the functionalized-OVGs, the imaging signal-to-noise ratio at 24 h timepoint was enhanced by approximately threefold and sevenfold as compared to non-functionalized OVGs and the non-encapsulated dye, respectively. These functionalized virus-mimicking NIR nano-constructs could potentially be used for intraoperative visualization of ovarian tumors implants.

Evaluation of a novel navigation platform for laparoscopic liver surgery with organ deformation compensation using injected fiducials

In laparoscopic liver resection, surgeons conventionally rely on anatomical landmarks detected through a laparoscope, preoperative volumetric images and laparoscopic ultrasound to compensate for the challenges of minimally invasive access. Image guidance using optical tracking and registration procedures is a promising tool, although often undermined by its inaccuracy. This study evaluates a novel surgical navigation solution that can compensate for liver deformations using an accurate and effective registration method. The proposed solution relies on a robotic C-arm to perform registration to preoperative CT/MRI image data and allows for intraoperative updates during resection using fluoroscopic images. Navigation is offered both as a 3D liver model with real-time instrument visualization, as well as an augmented reality overlay on the laparoscope camera view. Testing was conducted through a pre-clinical trial which included four porcine models. Accuracy of the navigation system was measured through two evaluation methods: liver surface fiducials reprojection and a comparison between planned and navigated resection margins. Target Registration Error with the fiducials evaluation shows that the accuracy in the vicinity of the lesion was 3.78±1.89 mm. Resection margin evaluations resulted in an overall median accuracy of 4.44 mm with a maximum error of 9.75 mm over the four subjects. The presented solution is accurate enough to be potentially clinically beneficial for surgical guidance in laparoscopic liver surgery.

Evaluation of a marker-less, intra-operative, augmented reality guidance system for robot-assisted laparoscopic radical prostatectomy

PURPOSE

Robot-assisted laparoscopic radical prostatectomy (RALRP) using the da Vinci surgical robot is a common treatment for organ-confined prostate cancer. Augmented reality (AR) can help during RALRP by showing the surgeon the location of anatomical structures and tumors from preoperative imaging. Previously, we proposed hand-eye and camera intrinsic matrix estimation procedures that can be carried out with conventional instruments within the patient during surgery, take < 3 min to perform, and fit seamlessly in the existing surgical workflow. In this paper, we describe and evaluate a complete AR guidance system for RALRP and quantify its accuracy.

METHODS

Our AR system requires three transformations: the transrectal ultrasound (TRUS) to da Vinci transformation, the camera intrinsic matrix, and the hand-eye transformation. For evaluation, a 3D-printed cross-wire was visualized in TRUS and stereo endoscope in a water bath. Manually triangulated cross-wire points from stereo images were used as ground truth to evaluate overall TRE between these points and points transformed from TRUS to camera.

RESULTS

After transforming the ground-truth points from the TRUS to the camera coordinate frame, the mean target registration error (TRE) (SD) was [Formula: see text] mm. The mean TREs (SD) in the x-, y-, and z-directions are [Formula: see text] mm, [Formula: see text] mm, and [Formula: see text] mm, respectively.

CONCLUSIONS

We describe and evaluate a complete AR guidance system for RALRP which can augment preoperative data to endoscope camera image, after a deformable magnetic resonance image to TRUS registration step. The streamlined procedures with current surgical workflow and low TRE demonstrate the compatibility and readiness of the system for clinical translation. A detailed sensitivity study remains part of future work.

Feasibility and usability of real-time intraoperative quantitative fluorescent-guided perfusion assessment during resection of gastroesophageal junction cancer. Langenbecks Arch Surg. 2020;405:215-222. [PMID: 32281020 DOI: 10.1007/s00423-020-01876-1]

PURPOSE

Anastomotic leakage after resection of gastroesophageal junction cancer is a dangerous complication, and leakage rates have remained stable for decades. Perfusion is crucial for anastomotic healing, but traditional perfusion assessment is limited in a minimally invasive environment. New methods as indocyanine green fluorescence angiography (ICG-FA) have proven promising, but quantitative analysis has been challenging. This study aimed to demonstrate the feasibility and usability of real-time intraoperative quantitative fluorescence angiography (q-ICG) with a touchscreen tablet.

METHODS

A software for q-ICG was previously developed and validated. Ten patients underwent perfusion assessment in white light (WL), with ICG-FA, and with q-ICG during Ivor-Lewis esophageal resection. The usability of the tablet-based software was tested with the System Usability Scale (SUS®). Furthermore, we investigated the differences in perfusion assessment as the distance from the conduit margin to a surgeon selected point of sufficient perfusion for anastomosis using the different modalities.

RESULTS

Q-ICG was successful in all patients, with an excellent median SUS® of 82.5 (77.5-93.8). Significant differences in distances from the conduit margin to points of sufficient perfusion selected by the surgeons were found: ICG: WL = 14.1 mm (p = 0.048), q-ICG: WL = 32.08 mm (p < 0.001), and q-ICG: ICG = 17.95 mm (p = 0.002). Furthermore, significant differences of perfusion were found between the points, when q-ICG was performed retrospectively in the surgeon selected areas (p = 0.008-0.013).

CONCLUSION

Real-time intraoperative touchscreen-based q-ICG was feasible with excellent usability, and differences in sufficient perfusion points selected by the surgeons between modalities were found. Further studies should focus on clinical relevance and determine cutoff values associated with anastomotic leakage.

Introducing fluorescence guided surgery into orthopedic oncology: A systematic review of candidate protein targets for Ewing sarcoma

Ewing sarcoma (ES), an aggressive bone and soft‐tissue tumor, is treated with chemotherapy, radiotherapy, and surgery. Intra‐operative distinction between healthy and tumorous tissue is of paramount importance but challenging, especially after chemotherapy and at complex anatomical locations. Near infrared (NIR) fluorescence‐guided surgery (FGS) is able to facilitate the determination of tumor boundaries intra‐operatively, improving complete resection and therefore survival. This review evaluates potential ES‐specific proteins from the literature as targets for NIR FGS.

PSMA-PET guided hook-wire localization of nodal metastases in prostate cancer: a targeted approach

Prostate Specific Membrane Antigen Positron Emission Tomography/Computed Tomography (PSMA-PET/CT) has increased the sensitivity and specificity of imaging to identify metastatic prostate cancer in the group of patients with early biochemical recurrence when compared to conventional imaging. In patients who develop biochemical recurrence of prostate cancer following surgical resection, salvage lymph node dissection may reduce prostate specific antigen (PSA) levels and delay the time for commencement of systemic therapies. However, PLND may be an anatomically and technically difficult procedure, particularly with small metastatic diseases which can be problematic for intra-operative identification. We describe the technique using PSMA-PET imaging to pre-operatively localise areas of low-volume nodal metastatic disease with hookwire to allow targeted lymph node dissection with direct visualisation and palpation to ensure adequate clearance of involved nodes.

Generation of fluorescently labeled tracers - which features influence the translational potential?

Given the increasing exploration of fluorescent tracers in the field of nuclear medicine, a need has risen for practical development guidelines that can help improve the translation aspects of fluorescent tracers. This editorial discusses the does and don'ts in developing fluorescence tracers. It has been put forward by the European Association of Nuclear Medicine (EANM) Translational Molecular Imaging & Therapy committee and has been approved by the EANM board.

Introducing navigation during melanoma-related sentinel lymph node procedures in the head-and-neck region

Background

Intraoperative sentinel node (SN) identification in patients with head-and-neck malignancies can be challenging due to unexpected drainage patterns and anatomical complexity. Here, intraoperative navigation-based guidance technologies may provide outcome. In this study, gamma camera-based freehandSPECT was evaluated in combination with the hybrid tracer ICG-^99mTc-nanocolloid.

Materials and methods

Eight patients with melanoma located in the head-and-neck area were included. Indocyanine green (ICG)-^99mTc-nanocolloid was injected preoperatively, whereafter lymphoscintigraphy and SPECT/CT imaging were performed in order to define the location of the SN(s). FreehandSPECT scans were generated in the operation room using a portable gamma camera. For lesion localization during surgery, freehandSPECT scans were projected in an augmented reality video-view that was used to spatially position a gamma-ray detection probe. Intraoperative fluorescence imaging was used to confirm the accuracy of the navigation-based approach and identify the exact location of the SNs.

Results

Preoperatively, 15 SNs were identified, of which 14 were identified using freehandSPECT. Navigation towards these nodes using the freehandSPECT approach was successful in 13 nodes. Fluorescence imaging provided optical confirmation of the navigation accuracy in all patients. In addition, fluorescence imaging allowed for the identification of (clustered) SNs that could not be identified based on navigation alone.

Conclusions

The use of gamma camera-based freehandSPECT aids intraoperative lesion identification and, with that, supports the transition from pre- to intraoperative imaging via augmented reality display and directional guidance.

Localization of the corticospinal tract within the porcine spinal cord: Implications for experimental modeling of traumatic spinal cord injury

Spinal cord injury (SCI) researchers have predominately utilized rodents for SCI modeling and experimentation. Unfortunately, a large number of novel therapies developed in rodent models have failed to demonstrate efficacy in human clinical trials which suggests that improved animal models are an important translational tool. Recently, porcine models of SCI have been identified as a valuable intermediary model for preclinical evaluation of promising therapies to aid clinical translation. However, the localization of the major spinal tracts in pigs has not yet been described. Given that significant differences exist in the location of the corticospinal tract (CST) between rodents and humans, determining its location in pigs will provide important information related to the translational potential of the porcine pre-clinical model of SCI. Thus, the goal of this study is to investigate the localization of the CST within the porcine spinal cord. Mature female domestic pigs (n=4, 60kg) received microinjections of fluorescent dextran tracers (Alexa Fluor, 10,000MW) into the primary motor cortex, using image-guided navigation (StealthStation^®), to label the CST. At 5 weeks post-tracer injection animals were euthanized, the entire neuroaxis harvested and processed for histological examination. Serial sections of the brain and spinal cord were prepared and imaged using confocal microscopy to observe the location of the CST in pigs. Results demonstrate that the CST of pigs is located in the lateral white matter, signifying greater similarity to human anatomical structure compared to that of rodents. We conclude that the corticospinal tract in pigs demonstrates anatomical similarity to human, suggesting that the porcine model has importance as a translational intermediary pre-clinical model.

Computer Aided Orthopaedic Surgery: Incremental shift or paradigm change?

Computer Aided Orthopaedic Surgery (CAOS) is now about 25 years old. Unlike Neurosurgery, Computer Aided Surgery has not become the standard of care in Orthopaedic Surgery. In this paper, we provide the technical and clinical context raised by this observation in an attempt to elucidate the reasons for this state of affairs. We start with a brief outline of the history of CAOS, review the main CAOS technologies, and describe how they are evaluated. We then identify some of the current publications in the field and present the opposing views on their clinical impact and their acceptance by the orthopaedic community worldwide. We focus on total knee replacement surgery as a case study and present current clinical results and contrasting opinions on CAOS technologies. We then discuss the challenges and opportunities for research in medical image analysis in CAOS and in musculoskeletal radiology. We conclude with a suggestion that while CAOS acceptance may be more moderate than that of other fields in surgery, it still has a place in the arsenal of useful tools available to orthopaedic surgeons.

Computational Modeling for Enhancing Soft Tissue Image Guided Surgery: An Application in Neurosurgery

With the recent advances in computing, the opportunities to translate computational models to more integrated roles in patient treatment are expanding at an exciting rate. One area of considerable development has been directed towards correcting soft tissue deformation within image guided neurosurgery applications. This review captures the efforts that have been undertaken towards enhancing neuronavigation by the integration of soft tissue biomechanical models, imaging and sensing technologies, and algorithmic developments. In addition, the review speaks to the evolving role of modeling frameworks within surgery and concludes with some future directions beyond neurosurgical applications.

Fiducial markers configuration optimization in image-guided surgery

The rigid registration is a key step of Image Guided Surgery (IGS), and the point-pair method is the main way used for registration. However the configuration of fiducial points has a great influence on the registration accuracy at the target point. Now almost all the optimization method of fiducial points configuration relies on the empirical simulation-based Fitzpatrick's target registration error (TRE). In this paper, a phantom and some markers were designed and some experiments were conducted to measure and compare the affecting factors on the registration. By the markers repeated selections, the fiducial location error (FLE) has a small deviation of maximum 0.4 mm, and the average of the Fitzpatrick's TRE (F-TRE) has almost 86% proportion to the average of the actual TRE (A-TRE), but the standard deviation (STD) just has 7% proportion. Also, the experiment result showed that six fiducial markers already had the 86% accuracy, and spreading the fiducial markers led to 30% reduction in mean of A-TRE and 40% reduction in STD of A-TRE comparing with the centralized. Overall, to find a strategy of optimization, reducing the TRE has the great meaning to support safer and more accurate minimally IGS procedures.

[Anterior odontoid screw fixation using intra-operative cone-beam computed tomography and navigation]

OBJECTIVE

The purpose of this study was to asses the value of intraoperative cone-beam CT (O-arm) and stereotactic navigation for the insertion of anterior odontoid screws.

MATERIALS AND METHODS

this was a retrospective review of patients receiving surgical treatment for traumatic odontoid fractures during a period of 18 months. Procedures were guided with O-arm assistance in all cases. The screw position was verified with an intraoperative CT scan. Intraoperative and clinical parameters were evaluated. Odontoid fracture fusion was assessed on postoperative CT scans obtained at 3 and 6 months' follow-up

RESULTS

Five patients were included in this series; 4 patients (80%) were male. Mean age was 63.6 years (range 35-83 years). All fractures were acute type ii odontoid fractures. The mean operative time was 116minutes (range 60-160minutes). Successful screw placement, judged by intraoperative computed tomography, was attained in all 5 patients (100%). The average preoperative and postoperative times were 8.6 (range 2-22 days) and 4.2 days (range 3-7 days) respectively. No neurological deterioration occurred after surgery. The rate of bone fusion was 80% (4/5).

CONCLUSION

Although this initial study evaluated a small number of patients, anterior odontoid screw fixation utilizing the O-arm appears to be safe and accurate. This system allows immediate CT imaging in the operating room to verify screw position.

A region-based anatomical landmark configuration for sinus surgery using image guided navigation system: a phantom-study

PURPOSE

To evaluate the current beliefs about the ways to reduce target registration error (TRE) values in image guided Sinus surgery by rearranging the fiducial configuration, and investigating the best configurations for various surgical fields in a phantom study.

METHODS

A new CT-compatible skull phantom consisting of implanted targets was designed to enable direct measurement of TRE in four fields of sinus surgery, Frontal, Ethmoid, Sphenoid and Maxillary. The effects of different landmark configurations on TRE values, measured by the Parsiss-IV navigation system were investigated to find the best landmark arrangement for each region, and compared to the TRE prediction formula to assess the clinically accepted landmark selection approaches based on this formula.

RESULTS

It was shown that smaller values of TRE could be attained by arranging the center of the fiducials to be more focused on the surgery target. The addition of more fiducials and keeping non-linear arrangement of landmark would not necessarily decrease the TRE value.

CONCLUSION

Optimizing the landmark configuration is important for increasing the localization accuracy in image guided sinus surgery. The common beliefs accepted in the clinical community about the ways to reduce the TRE are very general and should be adapted to specific field of image guided surgery.