Effect of display modality on spatial accuracy of orthopaedic surgery pre-operative planning applications

Graphical representation of a patient's anatomy is fairly similar in the majority of orthopaedic surgery planning programs. The position of implantable devices is usually established using a three-pane window showing 2D cross sections of the CT data set taken on three user-selectable orthogonal planes. In some cases this orthogonal-plane representation is replaced or extended by interactive 3D visualization, obtained using surface rendering techniques. These ways to represent the CT data come naturally and easily to the programmer. However, the efficacy of these display strategies is questionable. The present study aims to assess if the display modality used to visualize CT data affects the inherent spatial accuracy achievable in a surgical planning application. A group of users was asked to perform repeatedly a specific planning task using various display interfaces to the same underlying software application. The planning task was designed to allow an assessment of the accuracy with which each user was able to position the prosthetic component. A specialized interface, called multimodal display, presented a peak error of 0.45 mm and 0.95 deg, significantly lower than the 2.4 mm and 4 deg for the othogonal slices interface, and the 3.8 mm and 16.7 deg for the 3D-rendering interface. The results of this study indicate an important effect of the type of visualization modality used to represent CT data on final accuracy of the planning operation.     

Virtual palpation of skeletal landmarks with multimodal display interfaces

The 3D location of skeletal landmarks on CT datasets is an important procedure, used in many research and clinical contexts. The standard procedure involves the segmentation of the CT images, the creation of a 3D surface bone model, and the location of the landmarks on this surface. However, the segmentation is time-consuming and requires skilled operators and sophisticated software. The aim of the present study is to evaluate the efficacy of a multimodal display interface to direct volumetric interactive visualization in performing a virtual palpation task. An expert operator used the CT dataset of a patient's thigh region to locate 14 femoral skeletal landmarks. This operation was repeatedly performed using different CT data representation; the accuracy and repeatability were compared to those achievable with the conventional procedure based on the segmented 3D surface. When a multimodal display interface (formed by an orthogonal slice, RXCT and interactive isosurface views) was used to perform the virtual palpation directly on the CT data, the average coordinates of the landmarks did not differ significantly from those located on the 3D surface, and the measurement repeatability was actually better with the multimodal display of the volumetric data than with the 3D surface. Thus, we can conclude that skeletal virtual palpation can be performed directly on the CT dataset, as far as the virtual palpation is performed with a multimodal display interface.     

A comparative evaluation of human interaction for design and assembly of 3D CAD models in desktop and immersive environments

Computer aided design (CAD) systems have become today the basic tools used to design and develop products in the industry. In current CAD software most of the editing commands are issued with the aid of widgets and alphanumeric data input devices, while research community is proposing the use of virtual reality environments for CAD modelling. This paper presents an experimental study which compares the performance and usability of a multimodal immersive VR (virtual reality)-CAD system with a traditional CAD system. A comparative analysis was done for the modelling and the assembling process of 3D models. The results obtained from this investigation have shown that, in spite of the variety of interface devices in the virtual environment which provide a natural interaction to the user, the modelling time is about the same compared with a traditional desktop interface. The assembling time, however, is shown to be much smaller for multimodal system. Furthermore, the multimodal interface poses a higher physical stress factor, the hand movement distance being on average 1.6–2.3 times greater than the desktop interface for modelling process and assembling process, respectively. A post-experiment questionnaire shows that the multimodal system produce a great satisfaction for users in modelling and assembly processes.     

An image visualization tool in mammography

The poor detectability of diagnostic mammographic features, due to their low contrast, is dealt with by a software visualization tool. The tool is domain specific to medical imaging and consequently mammographic imaging, and it is envisaged as part of medical image visualization and manipulation stations. Domain specificity is served by the tool conformance to DICOM 3.0 part 10 image format specifications, specifically PAPYRUS 3.0, window width/level display adjustments of image dynamic range of up to 16 bits, and application of visualization operations to user-defined regions of interest in addition to global operations. The software has been designed and implemented according to an object oriented approach in Visual C++. The tool user interface is friendly, based on a widely used windowing paradigm, the Microsoft Foundation Class library version 4.2, which provides interface items, such as windows, dialogue boxes, lists, slide bars, buttons, etc. The visualization functionality offered by the tool relies on the following three categories of image processing algorithms: dynamic range adjustments by pixel intensity transformations, contrast enhancement and noise suppression by spatial domain direct manipulation of image pixels or by manipulation of wavelet coefficients. The first two categories of algorithms are implemented in real time. Initial use of the tool has demonstrated its potential in improving the detectability of diagnostic mammographic image features.     

A tool for designing digital test objects for module performance evaluation in medical digital imaging

Currently, medical digital imaging systems are characterized by the introduction of additional modules such as digital display, image compression and image processing, as well as film printing and digitization. These additional modules require performance evaluation to ensure high image quality. A tool for designing computer-generated test objects applicable to performance evaluation of these modules is presented. The test objects can be directly used as digital images in the case of film printing, display, compression and image processing, or indirectly as images on film in the case of digitization. The performance evaluation approach is quality control protocol based. Digital test object design is user-driven according to specifications related to the requirements of the modules being tested. The available quality control parameters include input/output response curve, high contrast resolution, low contrast discrimination, noise, geometric distortion and field uniformity. The tool has been designed and implemented according to an object oriented approach in Visual C++ 5.0, and its user interface is based on the Microsoft Foundation Class Library version 4.2, which provides interface items such as windows, dialog boxes, lists, buttons, etc. The compatibility with DICOM 3.0 part 10 image formats specifications allows the integration of the tool in the existing software framework for medical digital imaging systems. The capability of the tool is demonstrated by direct use of the test objects in case of image processing, and indirect use of the test objects in case of film digitization.     

Accuracy and repeatability of cementless total hip replacement surgery in patients with deformed anatomies

The present study is aimed to assess the repeatability of orthopaedic surgeons in planning total hip replacement surgery, and the Planned-vs.-Achieved accuracy obtainable with a conventional unassisted surgical procedure. A CT-based surgical planning system called Hip-Op was used for pre-operative planning the pose of the cementless components. The study group included only patients affected by severe deformities of the hip joint. In the repeatability study three surgeons were asked to repetitively plan the same three cases in a blind way. There was agreement among surgeons and also consistency for each surgeon in planning the implant position, while the most expert surgeon was more repeatable in planning the implant orientation. For all patients of the study group, the Planned-vs.-Achieved accuracy was computed as the difference between the spatial position of both prosthetic components derived from the post-operative CT scans and that achieved by the surgeon in the pre-operative planning. The average differences for the stem were lower than 5 mm for the position, and lower than 5 degrees for the orientation. For the socket the average differences increased to 8 mm and 10 degrees. The study shows the need for a more informative planning environment and for intra-operative supports, especially when deformed anatomies are involved.     

多模态影像融合技术在心脏疾病诊治中的应用研究进展

多模态影像融合技术旨在发挥不同成像模式的医学影像的优点，通过计算机图像拼接技术制作出更加精确的图像，达到优势互补，是医学影像学发展中的重大技术突破。心脏多模态影像融合可将多种无创成像技术获得的解剖学、形态学和功能数据组合起来，对冠心病、心脏瓣膜疾病、心脏再同步化治疗、心脏消融和心脏注射治疗等疾病进行更深入和准确的研究，为患者提供准确的诊断和预后信息。本文就多模态影像融合技术在心脏诊疗中的研究进展作一综述。     

Endorektale Sonographie

Endorectal sonography is a simple and dynamic procedure that has few side effects and can be performed as often as desired. It facilitates accurate localization of the pathological processes based on knowledge of anatomical structures and is valuable in making treatment decision during pre- and postoperative staging of rectal cancer. Endoanal sonography allows precise planning of sphincter-sparing surgery and planning of multimodal therapy.     

Three-dimensional spiral CT venography for the pre-operative assessment of varicose patients

BACKGROUND: The purpose of pre-operative spiral CT venography or veno-CT (VCT) is to provide a precise 3D anatomic depiction of the venous network, to be used as a guideline by the surgeon. METHODS: A multislice and multidetector spiral CT acquisition of the lower limb with diluted contrast injection produces about 400 slices in 30 s. Dedicated volume-rendering software compute interactive 3D images of the venous system. Dynamic data are easily exported by e-mail and available for phlebologists and surgeons. As VCT provides no hemodynamic data, an associated color-coded duplex is mandatory. RESULTS: VCT is useful in case of post-operative recurrence (especially of the popliteal fossa), high or dystrophic termination of the short saphenous vein, varices feeded by the Giacomini vein, and to investigate pelvic or pudental varicose veins. A full knowledge of the complex venous networks is possible thanks to interactivity of the resulting 3D model, using rotation and modification of transparency of the tissues. CONCLUSION: Providing a more complete anatomical information, VCT makes possible a better surgical choice of technique, avoiding anatomic pitfalls, with a more precise and limited skin approach. Accordingly, it may hopefully improve the aesthetic result as well as the efficacy, by reducing the varicose veins recurrence rate.     

Artificial intelligence assisted display in thoracic surgery: development and possibilities

In this golden age of rapid development of artificial intelligence (AI), researchers and surgeons realized that AI could contribute to healthcare in all aspects, especially in surgery. The popularity of low-dose computed tomography (LDCT) and the improvement of the video-assisted thoracoscopic surgery (VATS) not only bring opportunities for thoracic surgery but also bring challenges on the way forward. Preoperatively localizing lung nodules precisely, intraoperatively identifying anatomical structures accurately, and avoiding complications requires a visual display of individuals’ specific anatomy for surgical simulation and assistance. With the advance of AI-assisted display technologies, including 3D reconstruction/3D printing, virtual reality (VR), augmented reality (AR), and mixed reality (MR), computer tomography (CT) imaging in thoracic surgery has been fully utilized for transforming 2D images to 3D model, which facilitates surgical teaching, planning, and simulation. AI-assisted display based on surgical videos is a new surgical application, which is still in its infancy. Notably, it has potential applications in thoracic surgery education, surgical quality evaluation, intraoperative assistance, and postoperative analysis. In this review, we illustrated the current AI-assisted display applications based on CT in thoracic surgery; focused on the emerging AI applications in thoracic surgery based on surgical videos by reviewing its relevant researches in other surgical fields and anticipate its potential development in thoracic surgery.     

Interactive design of dental implant placements through CAD-CAM technologies: from 3D imaging to additive manufacturing

In the field of oral rehabilitation, the combined use of 3D imaging technologies and computer-guided approaches allows the development of reliable tools to be used in preoperative assessment of implant placement. In particular, the accurate transfer of the virtual planning into the operative field through surgical guides represents the main challenge of modern dental implantology. Guided implant positioning allows surgical and prosthetic approaches with minimal trauma by reducing treatment time and decreasing patient’s discomfort. This paper aims at defining a CAD/CAM framework for the accurate planning of flapless dental implant surgery. The system embraces three major applications: (1) freeform modelling, including 3D tissue reconstruction and 2D/3D anatomy visualization, (2) computer-aided surgical planning and customised template modelling, (3) additive manufacturing of guided surgery template. The tissue modelling approach is based on the integration of two maxillofacial imaging techniques: tomographic scanning and surface optical scanning. A 3D virtual maxillofacial model is created by matching radiographic data, captured by a CBCT scanner, and surface anatomical data, acquired by a structured light scanner. The pre-surgical planning process is carried out and controlled within the CAD application by referring to the integrated anatomical model. A surgical guide is then created by solid modelling and manufactured by additive techniques. Two different clinical cases have been approached by inserting 11 different implants. CAD-based planned fixture placements have been transferred into the clinical field by customised surgical guides, made of a biocompatible resin and equipped with drilling sleeves.     

Three-dimensional reconstruction of soft palate modeling from subject-specific magnetic resonance imaging data

Purpose

The objectives of this study were to extract a computational three-dimensional (3D) soft palate model from a set of magnetic resonance imaging (MRI) data and to identify an approach that generates a patient-specific model in a computerized visual platform.

Methods

Multiple MRI slices of the head and neck region of a young, non-overweight Caucasian male volunteer were taken in the supine position with a passive oral appliance in place. The DICOM (Digital Imaging and Communications) MRI slices were registered into a high-resolution volumetric data set for manually segmentation to generate a surface mesh and, with additional editing, a volume mesh. For biomechanical dynamic simulation and for physical simulation of the anatomical structures, the volume mesh format and multiple landmarks of each muscle were imported into ArtiSynth, a 3D biomechanical modeling toolkit.

Results

The segmented soft palate complex consisted of five groups of muscles: levator veli palatini, tensor veli palatini, palatoglossus, palatopharyngeous and musculus uvulae. The palatine tonsil between the pharyngopalatine and glossopalatine arches was included in the segmentation.

Conclusions

The same procedure was used to build up a generic reference model of the dentition, tongue, mandible and airway from a mixture of medical records (CT and dental casts) of the same subject. This manual segmentation method eliminated the common errors that occur from an automatic segmentation although it was more time-consuming. It remains a fundamental process for analyzing the dynamic interaction between anatomical components in the oral, pharyngeal, and laryngeal areas.     

Anatomical definition of aortic root abscesses by transesophageal echocardiography: Planning a surgical strategy using homograft valves

Infective endocarditis of the native or a prosthetic aortic valve may be complicated by abscess cavity development in the aortic root, and successful treatment depends upon early diagnosis, clear anatomical definition preoperatively, and maintaining sterility of the second implant. Homograft valves offer many advantages in this setting. Timing of surgery and the choice of the particular technique depends on accurate characterization of the anatomical details of the abscess. Five cases of paravalvular aortic root abscess in the setting of prosthetic valve endocarditis are described. In each case the diagnosis was made with transesophageal echocardiography, and the information was used in planning the operative procedure of homograft valve replacement. This strategy is proposed as optimal management of this potentially lethal condition.     

Performance Evaluation of a Multi-Slice CT System with 16-Slice Detector and Increased Gantry Rotation Speed for Isotropic Submillimeter Imaging of the Heart

BACKGROUND: 4-slice CT scanners have shown limitations in clinical application for noninvasive coronary CT angiography (CTA). We evaluate advances in ECG-gated scanning of the heart and the coronary arteries with recently introduced 16-slice CT equipment (SOMATOM Sensation 16, Siemens, Forchheim, Germany). MATERIALS AND METHODS: The technical principles of ECG-gated cardiac scanning, scan parameters, and detector design of the new scanner are presented. ECG-gated scan and image reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose are described, key parameters for image quality and simulation results presented, and phantom studies and initial patient experience discussed. The impact of reduced gantry rotation time (0.42 s) on temporal resolution and initial estimations of the patient dose are presented. RESULTS: Extensions of ECG-gated reconstruction algorithms used for 4-slice CT provide adequate image quality for up to 16 slices. For each detector collimation different slice widths are available for retrospective reconstruction with well-defined slice sensitivity profiles (SSPs). For coronary CTA the heart can be covered with 0.75 mm collimation within a 20-s breathhold. The best possible spatial resolution is 0.5 x 0.5 x 0.6 mm. For 0.42 s gantry rotation time, temporal resolution reaches its optimum (105 ms) at a heart rate of 81 bpm. Effective patient dose for coronary CTA is 4-5 mSv using ECG-pulsed acquisition. CONCLUSION: The clinical performance of coronary CTA by means of spatial resolution, temporal resolution and scan time is substantially improved with the evaluated 16-slice CT scanner. Also, display of smaller coronary segments and instent visualization are substantially improved.     

Selective Laser Melting and Electron Beam Melting of Ti6Al4V for Orthopedic Applications: A Comparative Study on the Applied Building Direction

The 3D printing process offers several advantages to the medical industry by producing complex and bespoke devices that accurately reproduce customized patient geometries. Despite the recent developments that strongly enhanced the dominance of additive manufacturing (AM) techniques over conventional methods, processes need to be continually optimized and controlled to obtain implants that can fulfill all the requirements of the surgical procedure and the anatomical district of interest. The best outcomes of an implant derive from optimal compromise and balance between a good interaction with the surrounding tissue through cell attachment and reduced inflammatory response mainly caused by a weak interface with the native tissue or bacteria colonization of the implant surface. For these reasons, the chemical, morphological, and mechanical properties of a device need to be designed in order to assure the best performances considering the in vivo environment components. In particular, complex 3D geometries can be produced with high dimensional accuracy but inadequate surface properties due to the layer manufacturing process that always entails the use of post-processing techniques to improve the surface quality, increasing the lead times of the whole process despite the reduction of the supply chain. The goal of this work was to provide a comparison between Ti6Al4V samples fabricated by selective laser melting (SLM) and electron beam melting (EBM) with different building directions in relation to the building plate. The results highlighted the influence of the process technique on osteoblast attachment and mineralization compared with the building orientation that showed a limited effect in promoting a proper osseointegration over a long-term period.     

An Intensive Insulinotherapy Mobile Phone Application Built on Artificial Intelligence Techniques

Background

Software to help control diabetes is currently an embryonic market with the main activity to date focused mainly on the development of noncomputerized solutions, such as cardboard calculators or computerized solutions that use “flat” computer models, which are applied to each person without taking into account their individual lifestyles. The development of true, mobile device-driven health applications has been hindered by the lack of tools available in the past and the sheer lack of mobile devices on the market. This has now changed, however, with the availability of pocket personal computer handsets.

Method

This article describes a solution in the form of an intelligent neural network running on mobile devices, allowing people with diabetes access to it regardless of their location. Utilizing an easy to learn and use multipanel user interface, people with diabetes can run the software in real time via an easy to use graphical user interface. The neural network consists of four neurons. The first is glucose. If the user''s current glucose level is within the target range, the glucose weight is then multiplied by zero. If the glucose level is high, then there will be a positive value multiplied to the weight, resulting in a positive amount of insulin to be injected. If the user''s glucose level is low, then the weights will be multiplied by a negative value, resulting in a decrease in the overall insulin dose.

Results

A minifeasibility trial was carried out at a local hospital under a consultant endocrinologist in Belfast. The short study ran for 2 weeks with six patients. The main objectives were to investigate the user interface, test the remote sending of data over a 3G network to a centralized server at the university, and record patient data for further proofing of the neural network. We also received useful feedback regarding the user interface and the feasibility of handing real-world patients a new mobile phone. Results of this short trial confirmed to a large degree that our approach (which also can be known as intensive insulinotherapy) has value and perhaps that our neural network approach has implications for future intelligent insulin pumps.

Conclusions

Currently, there is no software available to tell people with diabetes how much insulin to inject in accordance with their lifestyle and individual inputs, which leads to adjustments in software predictions on the amount of insulin to inject. We have taken initial steps to supplement the knowledge and skills of health care professionals in controlling insulin levels on a daily basis using a mobile device for people who are less able to manage their disease, especially children and young adults.     

A novel augmented reality-based interface for robot path planning

Intuitive and efficient interfaces for robot task planning have been a challenging issue in robotics as it is essential for the prevalence of robots supporting humans in key areas of activities. This paper presents a novel augmented reality (AR) based interface for interactive robot path and end-effector (EE) orientation planning. A number of human-virtual robot interaction methods have been formulated and implemented with respect to the various types of robotic operations needed in different applications. A Euclidean distance-based method is developed to assist the users in the modification of the waypoints so as to update the planned paths and/or orientation profiles within the proposed AR environment. The virtual cues augmented in the real environment can support and enhance human-virtual robot interaction at different stages of the robot tasks planning process. Two case studies are presented to demonstrate the successful implementation of the proposed AR-based interface in planning robot pick-and-place tasks and path following tasks.     

Utility of simple radiation dose measurements in the evaluation of different CT scanners used for high-resolution CT

In recent years radiation risk from CT scanning has become an important area of investigation. Many authors have suggested that radiation dose can be decreased without loss of diagnostic information. This dose reduction has primarily been achieved through a decrease in tube current. An area that has received little attention has been variations in dose from different CT scanners. To evaluate this aspect of radiation exposure, we measured the radiation dose of 4 different CT scanners. We found that the radiation dose for the same CT technique can vary by as much as a factor of 3 when 1 mm slices are used. CT dose variation was greatest for thin slices, making these observations particularly important for high-resolution CT. Our measurement technique used standard quality assurance equipment available in most radiology departments. Use of these measurements to assess the radiation dose from different CT scanners is an easily performed technique that may allow a decrease in radiation exposure in departments by choosing the most appropriate intra departmental CT scanner for specific indications.     

Some technical considerations in tomographic coronary arteriography

Summary Coronary artery anatomy can be visualized using high-speed, volume scanning x-ray CT. A single scan during a bolus injection of contrast medium provides image data for display of all angles of view of the opacified coronary arterial tree. Due to the tomographic nature of volume image data, the superposition of the vessels on themselves and on other contrast filled coronary arteries, such as would occur in an aortic root injection of contrast agent, can be eliminated.To achieve the goal of coronary arteriography using a single angiographic injection, the tomographic scanner must scan the entire volume encompassing the coronary arteries synchronously and within a brief period of time. The volume must be scanned so that the thickness of the scanned slices is less than the diameter of the smallest vessel desired to be visualized quantitatively. Preliminary results from a fast volume scanning CT scanner (the Dynamic Spatial Reconstructor) used to scan experimental animals are used to indicate the quantitative and qualitative impact of such varibles as scanned slice thickness, scanned slice separation and angle between the vessel and the plane of the scanned slices.This work was supported in part by NIH Grants HL-04664, HL-38042 and RR-02540.