Preoperative 3D Model Research Articles

Preliminary use of HoloLens glasses in surgery of liver cancer

To establish the preoperative three dimensional (3D) model of liver cancer, and to precisely match the preoperative planning with the target organs during the operation. Methods: The 3D model reconstruction based on magnetic resonance data, which was combined with virtual reality technology via HoloLens glasses, was applied in the operation of liver cancer to achieve preoperative 3D modeling and surgical planning, and to directly match it with the operative target organs during operation. Results: The 3D model reconstruction of liver cancer based on magnetic resonance data was completed. The exact match with the target organ was performed during the operation via HoloLens glasses leaded by the 3D model. Conclusion: Magnetic resonance data can be used for the 3D model reconstruction to improve preoperative assessment and accurate match during the operation.

Relationships Between the Axial Derotation of the Lower Instrumented Vertebra and Uninstrumented Lumbar Curve Correction: Radiographic Outcome in Lenke 1 Adolescent Idiopathic Scoliosis With a Minimum 2-Year Follow-up.

Preoperative spinal parameters are used to guide the fusion levels in adolescent idiopathic scoliosis (AIS) spinal surgery. However, the impact of the factors modifiable by the surgeon in varying levels of preoperative patient-specific variables is not fully explored. The goal of this study was to identify the association between axial rotation correction of the lower instrumented vertebra (LIV) and spontaneous correction of the uninstrumented lumbar spine as a function of preoperative 3 dimensional (3D) curve characteristics in Lenke 1 AIS. Twenty-three Lenke1 AIS with a minimum 2-year follow-up were included. All patients had biplanar spinal x-rays and 3D reconstructions at preoperative, first erect, and 2-year follow-up visits. Five patient factors were measured preoperatively: kyphosis and lumbar modifiers, and thoracic to lumbar curve rotation, translation, and frontal deformity angle ratios. One surgical factor, percentage of LIV rotation correction, was determined from the preoperative and first erect 3D models. A factorial design analysis was implemented to determine the impact of surgical and patient factors, both separately and in combination, on 2-year radiographic outcomes of spontaneous correction of the uninstrumented spine. Spontaneous lumbar Cobb and lumbar apical rotation correction were predicted significantly by patient and surgical factors, P<0.05. Lumbar modifier, percentage correction of LIV rotation, the interaction between LIV rotation correction and lumbar modifier, and the interaction between LIV rotation correction and thoracic to lumbar apical vertebrae translation ratio correlated significantly to 2-year outcomes of spontaneous lumbar Cobb correction, P<0.05. Lumbar modifier and the interaction between the Cobb ratio and the percentage of the LIV rotation correction correlated significantly to 2-year outcomes of lumbar apical rotation correction, P<0.05. The relationship between LIV rotation correction and spontaneous lumbar curve correction after selective thoracic fusion varied based on the patient's 3D preoperative curve characteristics. Patients with lumbar modifier C and apical vertebrae translation ratios >1.5 showed improved lumbar Cobb correction in 2-years when 50% or more LIV rotation correction was achieved surgically.

Three-dimensional computed tomography reconstruction for operative planning in robotic segmentectomy: a pilot study.

The objective of our pilot study was to assess if three-dimensional (3D) reconstruction performed by Visible Patient™ could be helpful for the operative planning, efficiency and safety of robot-assisted segmentectomy. Between 2014 and 2015, 3D reconstructions were provided by the Visible Patient™ online service and used for the operative planning of robotic segmentectomy. To obtain 3D reconstruction, the surgeon uploaded the anonymized computed tomography (CT) image of the patient to the secured Visible Patient™ server and then downloaded the model after completion. Nine segmentectomies were performed between 2014 and 2015 using a pre-operative 3D model. All 3D reconstructions met our expectations: anatomical accuracy (bronchi, arteries, veins, tumor, and the thoracic wall with intercostal spaces), accurate delimitation of each segment in the lobe of interest, margin resection, free space rotation, portability (smartphone, tablet) and time saving technique. We have shown that operative planning by 3D CT using Visible Patient™ reconstruction is useful in our practice of robot-assisted segmentectomy. The main disadvantage is the high cost. Its impact on reducing complications and improving surgical efficiency is the object of an ongoing study.

3D Modeling of Lower Extremities With Biplanar Radiographs: Reliability of Measures on Subsequent Examinations.

Biplanar radiography with 3-dimensional (3D) modeling (EOS) provides a comprehensive assessment of lower limb alignment in an upright weight-bearing position with less radiation than conventional radiography. A study was performed to assess the consistency and reliability of 2 lower extremity 3D biplanar radiograph models created at least 1 year apart in a pediatric population. All patients who had 2 lower extremity radiographic evaluations with EOS performed at visits a minimum of 1 year apart were reviewed. Digital radiographs, of lower extremities in both frontal and sagittal planes, were acquired simultaneously, using the EOS system. The 3D reconstruction of the images was achieved utilizing the SterEOS software. Pelvic position, femoral and tibial anatomy, and the torsional profile were evaluated and compared using t tests. In total, 53 patients with a mean age of 11.7 years (range, 6.1 to 18.9 y) met inclusion criteria. When comparing 3D models between visits, minimal differences were noted in proximal femoral anatomy and pelvic alignment (pelvic incidence, sacral slope, sagittal tilt, neck shaft angle). Expected differences in femoral and tibial length corresponded with normal longitudinal growth between visits. Sagittal plane knee position varied widely between examinations. Femoral and/or tibial rotational osteotomies were performed in 37% of extremities between examinations. After femoral derotational osteotomy, a significant difference in femoral anteversion was appreciated when comparing preoperative and postoperative 3D models. However, this difference was less than the expected difference based on the anatomic correction achieved intraoperatively. No differences were noted in tibial torsion measures after tibial derotational osteotomy. The 3D modeling based on biplanar radiographs provides consistent and reliable measures of pelvic and hip joint anatomy of the lower extremity. Patient positioning may influence the reproducibility of knee alignment. The torsional profile assessment did not accurately reflect changes obtained by derotational osteotomy. Level III.

Mandibular defect reconstruction utilizing preoperative 3D modeling, plate pre-bending and a novel triad graft: a case report

Stomatological Disease and Science is an open acccess journal, which publishes articles in the field of stomatological research, oral surgery, oral medicine, oral pathology, oral radiology, oral cancer etc.

Accurate 3D reconstruction of bony surfaces using ultrasonic synthetic aperture techniques for robotic knee arthroplasty

Robotically guided knee arthroplasty systems generally require an individualized, preoperative 3D model of the knee joint. This is typically measured using Computed Tomography (CT) which provides the required accuracy for preoperative surgical intervention planning. Ultrasound imaging presents an attractive alternative to CT, allowing for reductions in cost and the elimination of doses of ionizing radiation, whilst maintaining the accuracy of the 3D model reconstruction of the joint. Traditional phased array ultrasound imaging methods, however, are susceptible to poor resolution and signal to noise ratios (SNR). Alleviating these weaknesses by offering superior focusing power, synthetic aperture methods have been investigated extensively within ultrasonic non-destructive testing. Despite this, they have yet to be fully exploited in medical imaging.In this paper, the ability of a robotic deployed ultrasound imaging system based on synthetic aperture methods to accurately reconstruct bony surfaces is investigated. Employing the Total Focussing Method (TFM) and the Synthetic Aperture Focussing Technique (SAFT), two samples were imaged which were representative of the bones of the knee joint: a human-shaped, composite distal femur and a bovine distal femur. Data were captured using a 5MHz, 128 element 1D phased array, which was manipulated around the samples using a robotic positioning system. Three dimensional surface reconstructions were then produced and compared with reference models measured using a precision laser scanner. Mean errors of 0.82mm and 0.88mm were obtained for the composite and bovine samples, respectively, thus demonstrating the feasibility of the approach to deliver the sub-millimetre accuracy required for the application.

3D printed renal cancer models derived from MRI data: application in pre-surgical planning.

To determine whether patient-specific 3D printed renal tumor models change pre-operative planning decisions made by urological surgeons in preparation for complex renal mass surgical procedures. From our ongoing IRB approved study on renal neoplasms, ten renal mass cases were retrospectively selected based on Nephrometry Score greater than 5 (range 6-10). A 3D post-contrast fat-suppressed gradient-echo T1-weighted sequence was used to generate 3D printed models. The cases were evaluated by three experienced urologic oncology surgeons in a randomized fashion using (1) imaging data on PACS alone and (2) 3D printed model in addition to the imaging data. A questionnaire regarding surgical approach and planning was administered. The presumed pre-operative approaches with and without the model were compared. Any change between the presumed approaches and the actual surgical intervention was recorded. There was a change in planned approach with the 3D printed model for all ten cases with the largest impact seen regarding decisions on transperitoneal or retroperitoneal approach and clamping, with changes seen in 30%-50% of cases. Mean parenchymal volume loss for the operated kidney was 21.4%. Volume losses>20% were associated with increased ischemia times and surgeons tended to report a different approach with the use of the 3D model compared to that with imaging alone in these cases. The 3D printed models helped increase confidence regarding the chosen operative procedure in all cases. Pre-operative physical 3D models created from MRI data may influence surgical planning for complex kidney cancer.

Ultrasound image based visual servoing for moving target ablation by high intensity focused ultrasound.

BackgroundAlthough high intensity focused ultrasound (HIFU) is a promising technology for tumor treatment, a moving abdominal target is still a challenge in current HIFU systems. In particular, respiratory‐induced organ motion can reduce the treatment efficiency and negatively influence the treatment result. In this research, we present: (1) a methodology for integration of ultrasound (US) image based visual servoing in a HIFU system; and (2) the experimental results obtained using the developed system.Materials and methodsIn the visual servoing system, target motion is monitored by biplane US imaging and tracked in real time (40 Hz) by registration with a preoperative 3D model. The distance between the target and the current HIFU focal position is calculated in every US frame and a three‐axis robot physically compensates for differences. Because simultaneous HIFU irradiation disturbs US target imaging, a sophisticated interlacing strategy was constructed.ResultsIn the experiments, respiratory‐induced organ motion was simulated in a water tank with a linear actuator and kidney‐shaped phantom model. Motion compensation with HIFU irradiation was applied to the moving phantom model. Based on the experimental results, visual servoing exhibited a motion compensation accuracy of 1.7 mm (RMS) on average. Moreover, the integrated system could make a spherical HIFU‐ablated lesion in the desired position of the respiratory‐moving phantom model.ConclusionsWe have demonstrated the feasibility of our US image based visual servoing technique in a HIFU system for moving target treatment.

Minimally invasive fixation in tibial plateau fractures using an pre-operative and intra-operative real size 3D printing

The purpose of our study was to compare the outcome after minimally invasive reconstruction and internal fixation with and without the use of pre- and intra-operative real size 3D printing for patients with displaced tibial plateau fractures (TPFs). We prospectively followed up 40 consecutive adult patients with closed TPF who underwent surgical treatment of reconstruction of the tibial plateau with the use of minimally invasive fixation. Sixteen patients (group 1) were operated using a pre-operative and intra-operative real size 3D-model, while 24 patients (group 2) were operated without 3D-model printing, but using only pre-operative and intra-operative 3D Tc-scan images. The mean operating time was 148.2±15.9min for group 1 and 174.5±22.2min for group 2 (p=0.041). In addition, the mean intraoperative blood loss was less in group 1 (520mL) than in group 2 (546mL) (p=0.534). After discharge, all patients were followed up at 6 weeks, 12 weeks, 6 months, 1year and then every year post surgically and radiographic evaluation was carried out each time using clinical and radiological Rasmussen’s score, with no significant differences between the two groups. Two patients (group 2) developed infection which resolved within 3 weeks after usage of antibiotics. Neither superficial nor deep infections were present in group 1. In all patients, no non-union occurred. No intraoperative, perioperative, or postoperative complications, such as loss of valgus correction, bone fractures, or metallic plate failures were detected at follow-up. In patients operated with the use of 3D-model printing, we found a significant reduction in surgical time. Moreover, the technique without a 3D-model increased the patient’s and the surgeon’s exposure to radiation.

Mandibular reconstruction after cancer: an in-house approach to manufacturing cutting guides

The restoration of mandibular bone defects after cancer can be facilitated by computer-assisted preoperative planning. The aim of this study was to assess an in-house manufacturing approach to customized cutting guides for use in the reconstruction of the mandible with osteocutaneous free flaps. A retrospective cohort study was performed, involving 18 patients who underwent mandibular reconstruction with a fibula free flap at three institutions during the period July 2012 to March 2015. A single surgeon designed and manufactured fibula and mandible cutting guides using a computer-aided design process and three-dimensional (3D) printing technology. The oncological outcomes, production parameters, and quality of the reconstructions performed for each patient were recorded. Computed tomography scans were acquired after surgery, and these were compared with the preoperative 3D models. Eighteen consecutive patients with squamous cell carcinoma underwent surgery and then reconstruction using this customized in-house surgical approach. The lengths of the fibula bone segments and the angle measurements in the simulations were similar to those of the postoperative volume rendering (P=0.61). The ease of access to 3D printing technology has enabled the computer-aided design and manufacturing of customized cutting guides for oral cancer treatment without the need for input from external laboratories.

Registering imaged ECoG electrodes to human cortex: A geometry-based technique

BackgroundThe accurate localization of implanted ECoG electrodes over the brain is of critical importance to invasive diagnostic work-up for the surgical treatment of intractable epileptic seizures. The implantation of subdural electrodes is an invasive procedure which typically introduces non-uniform deformations of a subject’s brain, increasing the difficulty of determining the precise location of the electrodes vis-à-vis cortex. Formalization of this problem is used to define a novel solution for the optimal localization of subdural electrodes. New methodWe demonstrate that nonlinear transformation is required to accurately register the implanted electrodes to the non-deformed pre-surgical cortical surface, and that this problem is accommodated by utilizing known features of electrode geometry. Techniques to register chronically implanted subdural electrodes to the undistorted brain image are described and evaluated using simulated and clinical data. ResultsPrincipal Axis, our novel analysis method that estimates an electrode’s orientation by the moment of inertia of the solid electrode volume, proved to be the most reliable measure in both the simulated and clinical datasets. Comparison with existing methodsThis method of electrode translation along its principal axis is an improvement over other techniques, such as the limited view provided by intraoperative photography, and the image degradation inherent in post-operative MRI. ConclusionsThis technique compensates for alterations due to post-operative brain edema, and translates subdural electrodes to their original location on pre-operative MRI 3D models. This is helpful in the correct localization of seizure foci and functional mapping of epilepsy patients.

Holding versus seeing pathology. Three-dimensional printing of the bony pelvis for preoperative planning of a complex pelvis fracture: A case report.

Pelvic injuries are not uncommon. The complex anatomy of the pelvic bones, the complex pattern of injuries, associated important structures such as neurovascular bundles, and difficult access make the reduction and fixation of these fractures difficult. Often the surgical outcomes are not satisfactory. Three-dimensional (3D) imaging using computed tomography (CT) scan (3DCT) has been the mainstay of preoperative evaluation since the 1980s, however, even with these images it may be difficult to understand complex injury patterns. Preoperative printing of a 3D model using the same CT scan data allows surgeons to hold the pelvis in their hands and then plan appropriate treatment. We report one such case of complex pelvic injury and its management using the novel method of preoperative 3D model printing.

Improved alignment and operating room efficiency with patient-specific instrumentation for TKA.

Achieving accurate alignment in total knee arthroplasty (TKA) remains a concern. Patient-specific instrumentation (PSI) produced using preoperative 3D models was developed to offer surgeons a simplified, reliable, efficient and customised TKA procedure. In this prospective study, 60 patients underwent TKA with conventional instrumentation and 71 patients were operated on using PSI. The primary endpoint was surgical time. Secondary endpoints included operating room (OR) time, the number of instrument trays used and postoperative radiographic limb alignment. Compared to conventional instrumentation, PSI significantly reduced total surgical time by 8.9 ± 3.3 min (p=0.038), OR time by 8.6 ± 4.2 min (p=0.043), and the number of instrument trays by six trays (p<0.001). Mechanical axis malalignment of the lower limb of >3° was observed in 13% of PSI patients versus 29% with conventional instrumentation (p=0.043). PSI predicted the size of the femoral and tibial components actually used in 85.9% and 78.9% of cases, respectively. PSI improves alignment, surgical and OR time, reduces the number of instruments trays used compared to conventional instrumentation in patients undergoing TKA and results in fewer outliers in overall mechanical alignment in the coronal plane. Prospective comparative therapeutic study.

Three-dimensional planning and use of patient-specific guides improve glenoid component position: an in vitro study

Glenoid component positioning is a key factor for success in total shoulder arthroplasty. Three-dimensional (3D) measurements of glenoid retroversion, inclination, and humeral head subluxation are helpful tools for preoperative planning. The purpose of this study was to assess the reliability and precision of a novel surgical method for placing the glenoid component with use of patient-specific templates created by preoperative surgical planning and 3D modeling. A preoperative computed tomography examination of cadaveric scapulae (N = 18) was performed. The glenoid implants were virtually placed, and patient-specific guides were created to direct the guide pin into the desired orientation and position in the glenoid. The 3D orientation and position of the guide pin were evaluated by performing a postoperative computed tomography scan for each scapula. The differences between the preoperative planning and the achieved result were analyzed. The mean error in 3D orientation of the guide pin was 2.39°, the mean entry point position error was 1.05 mm, and the mean inclination angle error was 1.42°. The average error in the version angle was 1.64°. There were no technical difficulties or complications related to use of patient-specific guides for guide pin placement. Quantitative analysis of guide pin positioning demonstrated a good correlation between preoperative planning and the achieved position of the guide pin. This study demonstrates the reliability and precision of preoperative planning software and patient-specific guides for glenoid component placement in total shoulder arthroplasty.

Real-time advanced spinal surgery via visible patient model and augmented reality system

This paper presents an advanced augmented reality system for spinal surgery assistance, and develops entry-point guidance prior to vertebroplasty spinal surgery. Based on image-based marker detection and tracking, the proposed camera-projector system superimposes pre-operative 3-D images onto patients. The patients’ preoperative 3-D image model is registered by projecting it onto the patient such that the synthetic 3-D model merges with the real patient image, enabling the surgeon to see through the patients’ anatomy. The proposed method is much simpler than heavy and computationally challenging navigation systems, and also reduces radiation exposure. The system is experimentally tested on a preoperative 3D model, dummy patient model and animal cadaver model. The feasibility and accuracy of the proposed system is verified on three patients undergoing spinal surgery in the operating theater. The results of these clinical trials are extremely promising, with surgeons reporting favorably on the reduced time of finding a suitable entry point and reduced radiation dose to patients.

Design of the needle-driven robot for radio frequency ablation therapy based on ultrasound navigation

The ultrasonic image guided radio frequency ablation surgery is an effective technique in liver tumour treatment. However, the traditional surgery imposes a constraint for surgeons to have high precision in their hand?eye coordination. This paper discusses the design of an assisted medical robot system to reduce these requirements; the needle-driven robot system consists of needle-driven robot, 3D model navigation and a magnetic tracker. In the pre-operative phase, 3D model of the liver tumour is reconstructed and the needle insertion path is planed. In the intra-operative phase, the surgeon matches the pre-operative 3D model of the liver with real patient?s liver. Then, the needle-driven robot moves accurately at the target point where the surgeon inserts the needle into the liver tumour to destroy the tumour with microwave coagulation. A small and compact medical robot is proposed based on workspace optimisation in this paper. Experimental results show that the needle-driven robot location errors are less than 0.2 mm, whereas the robot ultrasound navigation system errors are less than 2.5 mm.

Recent advances in liver imaging

Liver surgery remains a difficult challenge in which preoperative data analysis and strategy definition may play a significant role in the success of the procedure. Medical image processing led to a major improvement of patient care by guiding the surgical gesture. From this initial data, new technologies of virtual reality and augmented reality can increase the potential of such images. The 3D modeling of the liver of patients from their CT scan or MRI thus allows an improved surgical planning. Simulation allows the procedure to be simulated preoperatively and offers the opportunity to train the surgical gesture before carrying it out. These three preoperative steps can be used intraoperatively thanks to the development of augmented reality, which consists of superimposing the preoperative 3D modeling of the patient onto the real intraoperative view of the patient and his/her organs. Augmented reality provides surgeons with a transparent view of the patient. This facilitated the intraoperative identification of the vascular anatomy and the control of the segmental arteries and veins in liver surgery, thus preventing intraoperative bleeding. It can also offer guidance due to the virtual improvement of their real surgical tools, which are tracked in real-time during the procedure. During the surgical procedure, augmented reality, therefore, offers surgeons a transparent view of their patient, which will lead to the automation of the most complex maneuvers. The new ways of processing and analyzing liver images have dramatically changed the approach to liver surgery.

3D visualization tool for minimally invasive discectomy assistance.

Multimodal fusion of 2D thoracoscopic images with a pre-operative 3D anatomical model of the spine is useful for minimally invasive surgical procedures using an angled monocular endoscope with varying focal length. An offline calibration procedure has been developed to compute initial endoscope parameters, such as lens distortion, focal length and optical center before surgery. An optical tracking system is used to update extrinsic parameters describing the position and orientation of the endoscope in real-time during the procedure. This calibration allows the registration of the thoracoscopic image sequence with a pre-operative MRI 3D model of the spine. Two visualization methods merging the 3D model and thoracoscopic image sequence have been developed using both augmented reality and augmented virtuality paradigms primarily as an aid for discectomy. Augmented views are generated by adding annotations and projecting the MRI 3D model onto real thoracoscopic images. Virtual views are generated by projecting the real thoracoscopic images on a virtual view of the 3D model. Experimental results showed that the calibration procedure accuracy obtained by computing the relative 3D reconstruction error on a known object was 1.0 mm. Two orthopedic surgeons assessed the generated views, confirming the relevance and added value of the proposed visualization tool for minimally invasive discectomy assistance.

Virtual reality system for planning minimally invasive neurosurgery

The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. After a short period of acclimatization, the system proved easy to operate and is currently used routinely for preoperative planning of difficult cases at the authors' institution. It was felt that working with a virtual reality multimodal model of the patient significantly improved surgical planning. The pathoanatomy in individual patients could easily be understood in great detail, enabling the authors to determine the surgical trajectory precisely and in the most minimally invasive way. The authors found the preoperative 3D model to be in high concordance with intraoperative conditions; the resulting intraoperative "déjà-vu" feeling enhanced surgical confidence. In all procedures planned with the Dextroscope, the chosen surgical strategy proved to be the correct choice. Three-dimensional virtual reality models of a patient allow quick and easy understanding of complex intracranial lesions.

Augmented Reality for Surgery and Interventional Therapy

This paper presents an advanced augmented reality system for spinal surgery assistance, and develops entry-point guidance prior to vertebroplasty spinal surgery. Based on image-based marker detection and tracking, the proposed camera-projector system superimposes pre-operative 3-D images onto patients. The patients’ preoperative 3-D image model is registered by projecting it onto the patient such that the synthetic 3-D model merges with the real patient image, enabling the surgeon to see through the patients’ anatomy. The proposed method is much simpler than heavy and computationally challenging navigation systems, and also reduces radiation exposure. The system is experimentally tested on a preoperative 3D model, dummy patient model and animal cadaver model. The feasibility and accuracy of the proposed system is verified on three patients undergoing spinal surgery in the operating theater. The results of these clinical trials are extremely promising, with surgeons reporting favorably on the reduced time of finding a suitable entry point and reduced radiation dose to patients.