3D Reconstruction Of CT Scan Research Articles

Study on impact resistance of sandwich glass based on CT scan-3D reconstruction

Utilizing the light gas gun system, impact tests on sandwich glass specimens with various structural configurations were performed at high-speed, medium-speed, and low-speed to evaluate the impact resistance of polyvinyl butyral (PVB) sandwich glass. An impact damage test method that incorporates stress data and three-dimensional fracture data was proposed in conjunction with the CT scan-3D reconstruction technique. The experimental findings demonstrated that as glass thickness grew, sandwich glass’ rigidity increased noticeably, and impact resistance of sandwich glass was significantly improved. On the other hand, under the action of elastic deformation energy absorption and horizontal cohesion of the PVB interlayer, the thicker interlayer could consume and disperse more impact energy, making the veins radially distributed and reducing the flying of debris. The conclusion that thin glass-thick interlayer could equivalently replace thick glass-thin interlayer to a certain extent was obtained. The study offers crucial technological backing for sandwich glass’s industrial applicability.

A rare case surgery repair for pediatric sphenoethmoidal encephalocele with single-step transfrontobasal approach

Link of Vidio Abstract: https://youtu.be/nsnfWQ81oRU Background: Basal encephalocele (BEC) is the rarest type of all encephaloceles. Several methods were used to close and repair the bony defect and prevent CSF leakage. Here we present a case of a 1-month-old pediatric patient who presented with a sphenoethmoidal basal encephalocele with a single transfrontobasal approach. Case Presentation: A female infant one-month-old with diagnosed large sphenoethmoid encephalocele (basal encephalocele). From the 3D CT scan reconstruction, we found a defect in the planum sellae and ethmoid region with a maximum line of 2.84 cm x 2.89 cm. We performed a transfrontobasal approach by using titanium mesh/plate. After follow-up, we did not find CSF leakage. Conclusion: Uncertainty persists on the best way to restore BEC. In this instance, we used single TBF approaches to seal and repair the basal encephalocele. There are no signs of infection or CSF leakage throughout the follow-up.

Retracted: Application Value of the CT Scan 3D Reconstruction Technique in Maxillofacial Fracture Patients.

[This retracts the article DOI: 10.1155/2022/1643434.].

Analysis of Imperative Facial Angles for Rhinoplasty: An Endowment to the Surgeon.

To study the nasal framework of patients in relation to CT scan and observe the Nasofrontal angle and Nasofacial angle in patients. This study is a prospective observational study. It was done from January 2020 to December 2020. It involved selection of patients with nasal complaints and external nasal deformity followed by their CT scan evaluation. It included a 3D analysis of the CT scan using a computer software. Preoperative photographic evaluation of the patient was done in frontal, lateral and basal view for a better understanding and correlation. Thirty patients were evaluated and their 3D reconstructed CT scans were observed. The mean Nasofrontal angle was 116.69°. The mean was 110.43° in males and 126.08° in females. The mean Nasofacial Angle was 37.68. The mean was 43.05° in males and 29.62° in females. There was a significant statistical difference seen. The demand for rhinoplasty in India is on rise. The studies done in the past have evaluated patients using plain 2D CT films. In this study, 3D reconstruction of CT scan has been done. There are meagre studies which describe the aesthetics of Indian population. It aids in preoperative evaluation and plan of surgery, enables a good doctor-patient communication. Also, it can be used for clinical learning of resident doctors.

Study on the effect of different sandwich materials on the impact resistance of laminated glass

In this paper, four types of laminated glass with various sandwich materials, polyvinyl butyral (PVB), polyurethane (PU), ethylene vinyl acetate (EVA), and SentryGlas® Plus (SGP), were selected to obtain the impact mechanical parameters and crack space development of laminated glass under different impact velocities by using light gas gun flyer plate variable velocity impact combined with CT scan-3D reconstruction technique. The findings demonstrated that different impact velocities had various demands on the elastic modulus of the sandwich material, showing the impact resistance demands of low velocity-high flexibility and high velocity-high rigidity. From the full-dimensional crack characterization under the medium-velocity impact, it could be seen that the comprehensive characteristics of the sandwich material viscosity, ductility, and rigidity led to different total volume, density, and spatial distribution complexity of cracks. This research provides important practical value and technical support for the selection and improvement of laminated glass.

Patient-individualized resection planning in liver surgery using 3D print and virtual reality (i-LiVR)—a study protocol for a prospective randomized controlled trial

BackgroundA multitude of different diseases—benign and malign—can require surgery of the liver. The liver is an especially challenging organ for resection planning due to its unique and interindividually variable anatomy. This demands a high amount of mental imagination from the surgeon in order to plan accordingly - a skill, which takes years of training to acquire and which is difficult to teach. Since the volume of the functional remnant liver is of great importance, parenchyma sparing resections are favoured. 3D reconstructions of computed tomography imaging enable a more precise understanding of anatomy and facilitate resection planning. The modality of presentation of these 3D models ranges from 2D monitors to 3D prints and virtual reality applications.MethodsThe presented trial compares three different modes of demonstration of a 3D reconstruction of CT scans of the liver, which are 3D print, a demonstration on a regular computer screen or using a head-mounted virtual reality headset, with the current gold standard of viewing the CT scan on a computer screen. The group size was calculated with n=25 each. Patients with major liver resections in a laparoscopic or open fashion are eligible for inclusion. Main endpoint is the comparison of the quotient between planned resection volume and actual resection volume between these groups. Secondary endpoints include usability for the surgical team as well as patient specifics and perioperative outcome measures and teaching issues.DiscussionThe described study will give insight in systematic planning of liver resections and the comparison of different demonstration modalities of 3D reconstruction of preoperative CT scans and the preference of technology. Especially teaching of these demanding operations is underrepresented in prior investigations.Trial registrationProspective trials registration at the German Clinical Trials register with the registration number DRKS00027865. Registration Date: January 24, 2022.

Biomechanical Comparison of Fibertape Augmentation with Intercuneiform Adjunct and Cannulated Screws for Ligamentous Lisfranc Injuries: 3D Visualization of Complex Movement

Category:Midfoot/Forefoot; Sports; TraumaIntroduction/Purpose:The preferred method of fixation for ligamentous Lisfranc injuries is controversial, with the traditional method being transarticular screws. Unfortunately screw removal is often required leading surgeons to seek alternative fixation methods including fibertape constructs. Our lab has published biomechanical results on the safety and efficacy of a fibertape construct for the treatment of ligamentous Lisfranc injuries demonstrating biomechanical superiority with the supplementation of an intercuneiform limb. The purpose of this biomechanical study is to compare transarticular screws to a fibertape construct under loading and utilizing 3D visualization software.Methods:Three matched pairs of cadaveric specimens were dissected to allow for the placement of three screws on the dorsal aspect of the each bone involved in the Lisfranc complex. The diastasis between bones were measured at three midfoot joints in the Lisfranc articulation while each specimen was loaded to 75% of donor bodyweight. Measurements were obtained for the pre- injured specimens. The MC-2MT joint was sectioned under fluoroscopic imaging and re-measured to produce at least 2 mm of gapping. Specimens were then fixed with either transarticular screws or fibertape with an intercuneiform limb and computed tomography scans were performed. Post-fixation measurements were obtained for 250 N of axial loading with subsequent 100 N increases up to 650 N. CT scans were imported as DICOM images and the three bones were segmented to analyze the gapping that occurred at the dorsal, interosseous, and plantar portions of the ligament.Results:There were no significant differences detected for the diastasis between bones in the Lisfranc complex between the fibertape and screws. After loading to 650 N, no specimens had reached a diastasis of 2 mm through coordinate digitized measurements (Figure 1A and B). At 650 N of loading the fibertape specimens displayed an average diastasis of 0.78 mm while the specimens fixed with screws also displayed an average diastasis of 0.78 mm. 3D diastasis measurements showed coordinate digitized measurements were within 0.2 mm of those measured from 3D reconstruction of CT scans. The largest diastasis occurred at the dorsal aspect of the ligament.Conclusion:The use of a fibertape device involving a supplementary intercuneiform limb appears to provide a biomechanically viable alternative to screws for ligamentous Lisfranc injuries. Diastasis was verified using 3D computer models. Future efforts involve increasing the number of specimens, applying cyclic loading, and determining the effects on each portion of the ligament for each fixation type.

Telerobotic interventions from a distance: an initial experience in 3D phantom mapping

IntroductionThe current COVID-19 pandemic has fostered several accelerations in “remote” patient care such as video and telephone clinics, as well as multidisciplinary collaborations using online platforms with experts consulting the local teams from a distance. The next logical step would be to also offer remote-controlled interventions which the expert operator not on site, but in support of the local team. This is especially valuable for complex interventions when either patient or expert operator can not be present at the same place.PurposeWe aimed to demonstrate that an expert operator located at far distance (Austria) could directly interact with the remote magnetic navigation system in London (UK) whilst mapping a 3D phantom using an electroanatomical mapping system.MethodTwo experienced operators of the magnetic navigation system were tasked with creating fast anatomic maps (FAM) of the atrial and ventricular chambers of a 3D phantom using remote magnetic navigation in combination with 3D electroanatomical mapping. One was located in the control room of the magnetic catheter lab (UK) and the second one was in Tirol, Austria and connected through a secure remote desktop connection (via high speed fibre optic cable). Using a solid tip magnetic catheter connected to a mechanical drive, all interactions with the system were carried out via the Odyssey platform. Acquisitions for right and left atrium, as well as right and left ventricles plus aorta was compared with regards to mapping duration, map completeness (as judged by the average distance of surface points from 3D CT scan reconstruction), total 3D map volume and need for additional radiation exposure during the mapping process.ResultsMapping time and map completeness when performed by the distant operator was not inferior to the local operator and both did not require any additional radiation exposure during the mapping process. Table 1 demonstrates the mean parameters for each chamber, respectively. Figure 1 depicts the matched data for chamber completeness as compared for the LA (green= local operator, pink= distant operator) using a contrast CT scan as the gold standard.ConclusionTelerobotic 3D mapping of a 3D phantom from a distance was equally fast delivered from the control room as compared to an operator located 1200 km away without compromising on map completeness. This demonstrates the feasibility of telerobotic interventions and stress the need for remote collaboration which is especially valuable when travel of patients and/or physician experts is restricted.Funding AcknowledgementType of funding sources: None. Matched data for aorta

Telerobotic interventions from a distance: an initial experience in 3D phantom mapping

Abstract Introduction The current COVID-19 pandemic has fostered several accelerations in “remote” patient care such as video and telephone clinics, as well as multidisciplinary collaborations using online platforms with experts consulting the local teams from a distance. The next logical step would be to also offer remote-controlled interventions which the expert operator not on site, but in support of the local team. This is especially valuable for complex interventions when either patient or expert operator can not be present at the same place. Purpose We aimed to demonstrate that an expert operator located at far distance (Austria) could directly interact with the remote magnetic navigation system in London (UK) whilst mapping a 3D phantom using an electroanatomical mapping system. Method Two experienced operators of the magnetic navigation system were tasked with creating fast anatomic maps (FAM) of the atrial and ventricular chambers of a 3D phantom using remote magnetic navigation in combination with 3D electroanatomical mapping. One was located in the control room of the magnetic catheter lab (UK) and the second one was in Tirol, Austria and connected through a secure remote desktop connection (via high speed fibre optic cable). Using a solid tip magnetic catheter connected to a mechanical drive, all interactions with the system were carried out via the Odyssey platform. Acquisitions for right and left atrium, as well as right and left ventricles plus aorta was compared with regards to mapping duration, map completeness (as judged by the average distance of surface points from 3D CT scan reconstruction), total 3D map volume and need for additional radiation exposure during the mapping process. Results Mapping time and map completeness when performed by the distant operator was not inferior to the local operator and both did not require any additional radiation exposure during the mapping process. Table 1 demonstrates the mean parameters for each chamber, respectively. Figure 1 depicts the matched data for chamber completeness as compared for the LA (green= local operator, pink= distant operator) using a contrast CT scan as the gold standard. Conclusion Telerobotic 3D mapping of a 3D phantom from a distance was equally fast delivered from the control room as compared to an operator located 1200 km away without compromising on map completeness. This demonstrates the feasibility of telerobotic interventions and stress the need for remote collaboration which is especially valuable when travel of patients and/or physician experts is restricted. Funding Acknowledgement Type of funding sources: None. Matched data for aorta

Left atrial appendage remodeling following percutaneous closure with WATCHMAN 2.5 and FLX: insights from the WATCH-DUAL registry

Abstract Background Percutaneous left atrial appendage closure (LAAC) has emerged as a valid option for prevention of thromboembolic events in patients with non-valvular atrial fibrillation and contraindications for oral anticoagulation. The most recent devices have been created to improve the intervention efficiency and to allow the procedure in a wider range of anatomies. The new-generation Watchman FLX (WMFLX) features a new design but its in vivo performances have not been compared to the previous WATCHMAN 2.5 (WM2.5) prosthesis. Hence, the data regarding conformability, compression and device-related LAA remodeling are scarce. Purpose To compare the anatomical results of WM2.5 and WMFLX implantation and impact on LAA dimensions. Methods This study included LAAC patients from the WATCH-DUAL registry who benefited from a pre- and post-intervention CT scan. The WATCH-DUAL study was a dual center observational study including all the LAAC procedures prospectively collected in local registries from two high-volume centres between November 2017 and December 2020. The LAA and device dimensions were measured in a centralized core lab by 3D CT scan reconstruction methods, focusing on the device landing zone (LZ/defined as the cross section of the appendage that was perpendicular to its axis and connected the circumflex artery to a point 1 to 2 cm inside the LAA). Results This analysis included n=107 patients (n=58 WMFLX, n=49 WM2.5). The patients clinical profiles didn't differ, except for a higher proportion of coronary artery disease in WM2.5 group. The LAA dimensions were comparable between groups. There was a significantly higher proportion of chickenwing shapes in the WMFLX patients. The mean device baseline diameter was in the WMFLX compared to the WM2.5 patients (28.8±0.5 vs. 25.7±0.4 mm, p<0.001). The median delay for CT control was 48 (43–62) days. The LZ area (451 (363–521) vs. 366 (260–459) mm2, p<0.001) and minimal diameter (23.0 (20.7–24.8) vs. 18.7 (15.9–21.8) mm, p<0.001) significantly increased after implantation among patients. The LZ area increase absolute value and percentage were 101 (18–151) mm2 and 28 (4–54) % respectively. The LZ dimensions increase was more pronounced in the WMFLX group: these patients exhibited post LAAC larger LZ area and dimensions compared to the WM2.5 cases. The LAA eccentricity was reduced after implantation: the ratio LZ maximal/LZ minimal diameter significantly decreased for all patients (r=1.28 (1.18–1.40) vs. 1.06 (1.05–1.09), p<0.001). Comparable results were observed in WMFLX and WM2.5 patients. A multivariable regression analysis demonstrated that baseline LAA length, baseline LZ eccentricity and WM FLX use were independent predictors of LAA remodeling/dimensions increase. Conclusion LAA dimensions increased over time at the site of WM prosthesis implantation suggesting a local positive appendage remodeling after procedure. This phenomenon appears to be more pronounced with the WMFLX device. Funding Acknowledgement Type of funding sources: None.

Finite element analysis of a human foot

The aim of this work is to quantitatively evaluate the stresses acting in a human foot in its upright standing position. In the analysis, both the human feet were modeled using three-dimensional finite element model and studied for the characteristics and performance. The human foot was created using the 3D reconstruction of CT scan. The bone structures were implanted in a mass of soft tissues. Both the foot models were meshed using tetrahedral elements duly incorporating the material properties. The stress distribution of the skeleton and the plantar surface during balanced standing were calculated along with the effect of the stress distribution. Finally, the FEA results of the foot models were compared with that of the experimental results available from the literature.

An efficient approach based on 3D reconstruction of CT scan to improve the management and monitoring of COVID-19 patients

PurposeTo reconstruct a 3D visualization from CT images of COVID-19 patients in order to improve understanding of the disease for better management and follow-up. Materials and methodsWe have retrieved CT images of 185 COVID-19 patients from the Cheikh Zaid International University Hospital in Rabat, Morocco. We then performed computer processing that allowed us to obtain a 3D visualization of these patients. ResultsIn this article, we have chosen to do 3D reconstruction of three specific cases among 185 patients:- Cases (A1, A2) which are negative RT-PCR patient with normal CT images.- Cases (B1, B2) which are positive RT-PCR patient with abnormal CT images.- Case (C) which is a negative RT-PCR patient with CT abnormalities.To improve our results and have a better quality of the 3D reconstruction, we used different algorithms and a specific row data processing. Conclusion3D reconstruction has a significant role in the diagnosis and management of COVID-19 patients. The quality and reliability of 3D reconstructions allow the clinician to make a quick and efficient diagnosis and avoid an eventual false negative (produced by the RT-PCR test). We suggest including chest 3D reconstruction in the patient management and prognosis evaluation.

Posterior endoscopic cervical foramiotomy and discectomy: clinical and radiological computer tomography evaluation on the bony effect of decompression with 2\xa0years follow-up

PurposeCervical radiculopathy is a common disabling cervical spine condition. Open anterior and posterior approaches are the conventional surgical treatment approaches with good clinical outcomes. However, the soft tissue damage in these procedures can lead to increase perioperative morbidity. Endoscopic spine surgery provides more soft tissue preservation than conventional approaches. We investigate the radiological and clinical outcomes of posterior endoscopic cervical foraminotomy and discectomy.MethodsA prospective clinical and radiological study with retrospective evaluation were done for 25 patients with 29 levels of cervical radiculopathy who underwent posterior endoscopic cervical discectomy from November 2016 to December 2018. Clinical outcomes of Visual Analogue Scale, Neck Disability Index and MacNab’s score were evaluated at pre-operative, post-operative 1 week, 3 months and final follow-up. Preoperative and post-operative final follow-up flexion and extension roentgenogram were evaluated for cervical stability assessment. Pre-operative and post-operative computer tomography cervical spine evaluation of foraminal length in ventro-dorsal, cephalad-caudal dimensions, sagittal foraminal area and using 3D CT reconstruction coronal decompression area were done.ResultsTwenty-nine levels of cervical radiculopathy underwent posterior endoscopic cervical decompression. The mean follow-up was 29.6 months, and the most common levels affected were C5/6 and C6/7. There was a complication rate of 12% with 2 cases of neurapraxia and one case of recurrent of prolapsed disc. There was no revision surgery in our series. There was significant clinical improvement in Visual Analogue Scale and Neck Disability Index. Prospective comparative study between preoperative and final follow-up mean improvement in VAS score was 5.08 ± 1.75, and NDI was 45.1 ± 13.3. Ninety-two percent of the patients achieved good and excellent results as per MacNab’s criteria. Retrospective evaluation of the radiological data showed significant increments of foraminal dimensions: (1) sagittal area increased 21.4 ± 11.2 mm2, (2) CT Cranio Caudal length increased 1.21 ± 1.30 mm and (3) CT ventro-dorsal length increased 2.09 ± 1.35 mm and (4) 3D CT scan reconstruction coronal decompression area increased 536 ± 176 mm2, p < 0.05.ConclusionUniportal posterior endoscopic cervical foraminotomy and discectomy are safe, efficient and precise choreographed set of technique in the treatment of cervical radiculopathy. It significantly improved clinical outcomes and achieved the objective of increasing in the cervical foramen size in our cohort of patients.

Noninvasive epicardial mapping for the diagnosis of arrhythmogenic cardiomyopathy in case of non-conclusive task force criteria

Because the Task Force Criteria (TFC) are often not sufficient, the diagnosis of arrhythmogenic cardiomyopathy (AC) remains a challenge. The finding of low voltage areas (LVA) in the triangle of dysplasia, during a mapping in the electrophysiology lab, supports AC diagnosis but at the cost of an invasive procedure. A new noninvasive ECG high-resolution mapping tool, using a 252 leads vest and a CT scan 3D reconstruction (CardioInsight Technologies, Inc., Cleveland, Ohio), has the potential to unmask early AC disease. To identify LVA in the triangle of dysplasia by an ECG noninvasive epicardial mapping system in patients with suspected AC and negative TFC. Five patients (pts) were included (3 males, 47.4 ± 12.6 years). Median follow-up was 26 months [18; 97]. Pts were divided according to TFC between AC possible/borderline with high clinical suspicion (2 pts, respectively 1 minor TFC & 1 major plus 1 minor TFC) and definite AC (3 pts). For each pt a noninvasive high-resolution epicardial mapping of both ventricles was performed. LVA were defined as < 30% of maximum ventricular voltage. The triangle of dysplasia including basal right ventricle (RV), RV outflow tract, and posterolateral left ventricle (LV) was specifically analyzed. The noninvasive epicardial voltage maps revealed LVA in the 3 sides of the triangle of dysplasia in both pts with high clinical suspicion of AC but non-conclusive TFC ( Fig. 1 ). Interestingly, these two pts had no major criteria by MRI (RV end-diastolic volume respectively 94 and 57 ml/m 2 , RV ejection fraction 51 and 69%, and homogeneous segmental contraction), suggesting an early stage of the disease. All pts with defined AC had LVA in ≥ 2 sides of the triangle of dysplasia. An ECG noninvasive epicardial mapping can improve the diagnosis of early stage AC by demonstrating the presence of previously unknown lesions in the triangle of dysplasia.

Development and manufacturing of a custom made implant regarding the new European Medical Device Regulation

Abstract New technologies are great opportunities for personalized medicine. Custom made implants can be very helpful for patients with severe bone defects or in case of bone tumor. Through the European Union it is regulated how many possibilities and restrictions all medical devices have. Because of critical vulnerabilities a new European Medical Device Regulation (MDR) was published in May 2017 and it will enter into force in May 2020. For the manufacturers of customized products it will change the documentation of the manufacturing and tracking of serious incidents. Patients with a pelvis defect of Paprosky IIb and higher can benefit from a custom made pelvis implant, because all planning steps according to biomechanic and bone contact to the implant can be designed and proofed during a reconstruction process. With regular modular implant systems, it probably can be a trial and error procedure during the surgery according to biomechanic and a stable position of the implant. Based on the 3D-Reconstruction of CT-Scans of a patient with a Paprosky 2b pelvis defect, a personalized acetabulum implant was designed. To maintain as much bone as possible, the implant was shaped to the remaining pelvic bone stock. Additive manufacturing gives the opportunity to produce custom made single items even in a quality that ful-fills the requirements of the MDR. Modern Selective Laser Melting (SLM) and Electron Beam melting (EBM) Systems are able to produce Titanium or CoCr parts in the ISO standards for Implants (ISO 5832 ff). In this study the process chain, starting from the reconstruction, to the design and the production of a custom made acetabulum cup was run through on an exemplary CTData of one patient. With this example, it was shown that it is possible, to establish a process, that is able to address surgical needs for patients that benefit from those techniques.

Holding Eternity in One's Hand: First Three-Dimensional Reconstruction and Printing of the Heart from 2700 Years-Old Egyptian Mummy.

The heart in ancient Egyptian mummification procedure is the central organ that should stay in place in the chest and waiting for the afterlife judgment. Here, we show the first case of three-dimensional (3D) CT scan reconstruction of a mummified heart from a person embalmed in Egypt around 2,700 years ago, and present a 3D printing of the same heart using a low-cost yet accurate 3D printer. A multi-slice computed tomography scanner was used to scan the mummy. We applied the following radiological protocol: 80 keV and 140 keV, 140 mAs, with a slice thickness of 0.9 mm. The mummified heart and ascending aorta were extracted with semi-automatic segmentation. We used a low-cost 3D printer (Up plus 2) using fusion deposition modeling technology. The 3D printed model was then painted with acrylic paint to color code structures of interest. The 3D CT multi-resolution imaging allows us to identify the gross anatomy of the heart, the ascending aorta, the pulmonary arteries, and the presence of multiple atherosclerosis lesions. Using 3D printed model we recognized upper auricle, vein cave inferior, and the two coronary arteries. The brachiocephalic artery, common carotid artery, and left subclavian artery were clearly cut to dissociate the heart from surrounding tissues. This multi-3D approach allows for a better understanding of complex and distorted anatomy of the mummified heart, of paleopathology (arteriosclerosis), and of mummification techniques. Anat Rec, 302:912-916, 2019. © 2018 Wiley Periodicals, Inc.

Augmented Reality of the Middle Ear Combining Otoendoscopy and Temporal Bone Computed Tomography.

Augmented reality (AR) may enhance otologic procedures by providing sub-millimetric accuracy and allowing the unification of information in a single screen. Several issues related to otologic procedures can be addressed through an AR system by providing sub-millimetric precision, supplying a global view of the middle ear cleft, and advantageously unifying the information in a single screen. The AR system is obtained by combining otoendoscopy with temporal bone computer tomography (CT). Four human temporal bone specimens were explored by high-resolution CT-scan and dynamic otoendoscopy with video recordings. The initialization of the system consisted of a semi-automatic registration between the otoendoscopic video and the 3D CT-scan reconstruction of the middle ear. Endoscope movements were estimated by several computer vision techniques (feature detectors/descriptors and optical flow) and used to warp the CT-scan to keep the correspondence with the otoendoscopic video. The system maintained synchronization between the CT-scan image and the otoendoscopic video in all experiments during slow and rapid (5-10 mm/s) endoscope movements. Among tested algorithms, two feature-based methods, scale-invariant feature transform (SIFT); and speeded up robust features (SURF), provided sub-millimeter mean tracking errors (0.38 ± 0.53 mm and 0.20 ± 0.16 mm, respectively) and an adequate image refresh rate (11 and 17 frames per second, respectively) after 2 minutes of procedure with continuous endoscope movements. A precise augmented reality combining video and 3D CT-scan data can be applied to otoendoscopy without the use of conventional neuronavigation tracking thanks to computer vision algorithms.

The Normal 3D Gleno-humeral Relationship and Anatomy of the Glenoid Planes.

Knowledge of the normal and pathological three-dimensional (3D) gleno-humeral relationship is imperative when planning and performing a total shoulder arthroplasty. Currently, two-dimensional (2D) parameters are used to describe this anatomy and despite the fact that these 2D measurements have a wide distribution in the normal population, they are commonly accepted. This broad distribution can be explained on one hand by anatomical factors and on the other hand, by positional errors. A 3D CT-scan reconstruction and evaluation can overcome this shortcoming and can be used to determine more accurately the surgical planes on the normal and pathological shoulder joint. There is, however, no consensus on which references should be used when studying this 3D relationship. This thesis describes the normal 3D gleno-humeral relationship and the best glenoid plane to use in surgery, based on 3D CT-scan. Furthermore, a glenoid aiming device that can be of surgical help in the reconstruction of the normal glenoid anatomy was developed based on these measurements.

Postoperative CT-scan 3D reconstruction of the calcaneus following lateral calcaneal lengthening osteotomy for flatfoot deformity in children. Is the surgical procedure potentially associated with subtalar joint damage?

BackgroundSeveral anatomical studies have shown that the articular facets of the calcaneus can present with different anatomy. This study assessed the 3D anatomy of lateral calcaneal lengthening (LCL) osteotomy in relation to the anterior and middle facet of the calcaneus in a group of skeletally immature patients treated for symptomatic flatfoot deformity. MethodsDuring the study period, 14 consecutive patients (10 males, 4 females) presenting symptomatic flatfoot (20 feet) with different aetiologies underwent LCL osteotomy and CT scan with 3D reconstruction of the operated feet. Anatomy of articular factes of the calcaneus were graded according to Bunning & Barnett’s classification. In order to assess clinical and functional outcome, all patients were evaluated according to Yoo et al.’s, Mosca’s and AOFAS clinical criteria before surgery and at last follow-up visit. ResultsDespite proving difficult to assess (10 out of 20 feet), dimensions of bone and joint structures revealed significant anatomical variations. In particular, working to Bunning & Barnett’s classification, anatomy of the articular facet varied significantly among patients, and in Bunning & Barnett type-B1 or B2 the LCL osteotomy necessarily violates the articular surface of the anterior and middle facet of the calcaneus due to the fact that the two facets are fused together (single articular surface). ConclusionsThese biometric notions allow a better understanding of the impact on articular facets of the calcaneus of the osteotomy procedure suggested by Evans and Mosca. We anticipate that the findings reported here should lead to improved techniques for assessing all bone structures of the hindfoot, support logical classifications of the different pathological situations, and ultimately lead to improved treatment strategies.

In vivo posterior cruciate ligament elongation in running activity after anatomic and non-anatomic anterior cruciate ligament reconstruction.

The goals of this study were to (1) investigate the in vivo elongation behaviour of the posterior cruciate ligament (PCL) during running in the uninjured knee and (2) evaluate changes in PCL elongation during running after anatomic or non-anatomic anterior cruciate ligament (ACL) reconstruction. Seventeen unilateral ACL-injured subjects were recruited after undergoing anatomic (n=9) or non-anatomic (n=8) ACL reconstruction. Bilateral high-resolution CT scans were obtained to produce 3D models. Anterolateral (AL) and posteromedial (PM) bundles insertion sites of the PCL were identified on the 3D CT scan reconstructions. Dynamic knee function was assessed during running using a dynamic stereo X-ray (DSX) system. The lengths of the AL and PM bundles were estimated from late swing through mid-stance. The contralateral knees served as normal controls. Control knees demonstrated a slight decrease in AL bundle and a significant decrease in PM bundle length following foot strike. Length and elongation patterns of the both bundles of the PCL in the anatomic ACL reconstruction group were similar to the controls. However, the change in dynamic PCL length was significantly greater in the non-anatomic group than in the anatomic reconstruction group after foot strike (p<0.05). The AL bundle length decreased slightly, and the PM bundle length significantly decreased after foot strike during running in uninjured knees. Anatomic ACL reconstruction maintained normal PCL elongation patterns more effectively than non-anatomic ACL reconstruction during high-demand, functional loading. These results support the use of anatomic ACL reconstruction to achieve normal knee function in high-demand activities. Case-control study, Level III.