SONOSim3D: a multimedia system for sonography simulation and education with an extensible case database

Optical ultrasound simulation-based training in obstetric sonography

Ultrasound is an imaging modality that is highly operator dependent. This article reviews the challenges in learning how to perform obstetric sonography, as well as the processes necessary to acquire expert performance skills in sonography. Simulation-based education and learning, and the value of medical simulation are also discussed. Ultrasound simulators are an effective means of teaching obstetric sonography, because it provides training, deliberate practice, and performance evaluation/feedback which allows continuous and critical self-evaluation. We review evidence that simulation can improve performance in obstetric ultrasound examination, review current simulators, and discuss the current problems/gaps in ultrasound simulation. Optical positioning ultrasound simulation is a novel high-fidelity simulation learning system, which addresses many of these problems/gaps and is introduced for the first time here.

Ultrasound simulation with deformable and patient-specific scatterer maps

PURPOSE

Ray-tracing-based simulations model ultrasound (US) interactions with a custom geometric anatomical model, where US texture can be emulated via real-time point-spread function convolutions of a tissue scatterer representation. Such scatterer representations for realistic appearance are difficult to parameterize or model manually and do not respond to volumetric deformations such as those caused with tissue compression by the probe. Herein we utilize brightness mode (B-mode) estimated scatterer maps for ray tracing and propose to enhance the realism of ray-tracing-based simulations by incorporating dynamic speckle patterns that change compliant with tissue deformation.

METHODS

In this work, we realistically simulate US texture deformations in the scatterer domain via back-projection of ray segments into a nominal state before sampling during simulation runtime. We estimate scatterer maps from background in vivo images using a pretrained generative adversarial network.

RESULTS

We demonstrated our proposed scatterer estimation and runtime background fusion method on simulated transvaginal US scans of detailed surface-based foetal models. We show the viability of modelling deformations in the scatterer domain at interactive frame rates of 28 frames per second. A quantitative and a qualitative evaluations indicated improved realism in comparison to the state of the art.

CONCLUSIONS

Transferring a background image in a scatterer representation enables us to capture anatomical content in a physical space, in which deformations can be incorporated physically consistently before convolving with a US point-spread function during simulation runtime. This then uses the same imaging model on both the background and the hand-crafted models leading to a consistent and seamless compounding of contents in the scatterer space.

Multi-ray medical ultrasound simulation without explicit speckle modelling

PURPOSE

To develop a medical ultrasound (US) simulation method using T1-weighted magnetic resonance images (MRI) as the input that offers a compromise between low-cost ray-based and high-cost realistic wave-based simulations.

METHODS

The proposed method uses a novel multi-ray image formation approach with a virtual phased array transducer probe. A domain model is built from input MR images. Multiple virtual acoustic rays are emerged from each element of the linear transducer array. Reflected and transmitted acoustic energy at discrete points along each ray is computed independently. Simulated US images are computed by fusion of the reflected energy along multiple rays from multiple transducers, while phase delays due to differences in distances to transducers are taken into account. A preliminary implementation using GPUs is presented.

RESULTS

Preliminary results show that the multi-ray approach is capable of generating view point-dependent realistic US images with an inherent Rician distributed speckle pattern automatically. The proposed simulator can reproduce the shadowing artefacts and demonstrates frequency dependence apt for practical training purposes. We also have presented preliminary results towards the utilization of the method for real-time simulations.

CONCLUSIONS

The proposed method offers a low-cost near-real-time wave-like simulation of realistic US images from input MR data. It can further be improved to cover the pathological findings using an improved domain model, without any algorithmic updates. Such a domain model would require lesion segmentation or manual embedding of virtual pathologies for training purposes.

Assessment of Paramedic Ultrasound Curricula: A Systematic Review

OBJECTIVE

Prehospital ultrasound is being applied in the field. The purpose of this systematic review is to describe evidence pertaining to ultrasound curricula for paramedics specifically, including content, duration, setting, design, evaluation, and application.

METHODS

Electronic searches of MEDLINE, Embase, CINAHL, and the Cochrane Center Register of Controlled Trials were conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Primary literature describing acute care ultrasound curricula for paramedics were included. Two authors independently extracted data and assessed quality using 2 validated tools.

RESULTS

Twelve studies with 187 paramedics were included. Curricula duration varied, with effective curricula teaching focused assessment with sonography for trauma (FAST) in 6 to 8 hours and pleural ultrasound in 25 minutes. FAST, pleural, and fracture-detection ultrasound are being applied in the field by paramedics; however, no literature exists describing application to detect cardiac standstill. Curricula combined didactic and hands-on components including simulation and evaluated competency using sensitivity and specificity of paramedic-performed ultrasound.

CONCLUSIONS

Paramedic ultrasound curricula in FAST and pleural ultrasound is feasible and time effective with successful application. Although fracture detection ultrasound is being used by the special operations forces, no comprehensive curriculum was described. Curricula designed to detect cardiac standstill have been too short, and successful application by paramedics has not been shown.

Learning ultrasound gesture database: building and application to musculoskeletal ultrasound exams

Our aim is to develop a frame work for virtually learning the ultrasound exams. In this paper we address the method used to build the image database required for this frame work. The used materiel and the proposed methodology are presented and explained. The realized prototype has been used to build the database of ultrasound images.

A review of computer-based simulators for ultrasound training

SUMMARY STATEMENT

Computer-based simulators for ultrasound training are a topic of recent interest. During the last 15 years, many different systems and methods have been proposed. This article provides an overview and classification of systems in this domain and a discussion of their advantages. Systems are classified and discussed according to the image simulation method, user interactions and medical applications. Computer simulation of ultrasound has one key advantage over traditional training. It enables novel training concepts, for example, through advanced visualization, case databases, and automatically generated feedback. Qualitative evaluations have mainly shown positive learning effects. However, few quantitative evaluations have been performed and long-term effects have to be examined.

On the usage of health records for the design of Virtual Patients: a systematic review

Background

The process of creating and designing Virtual Patients for teaching students of medicine is an expensive and time-consuming task. In order to explore potential methods of mitigating these costs, our group began exploring the possibility of creating Virtual Patients based on electronic health records. This review assesses the usage of electronic health records in the creation of interactive Virtual Patients for teaching clinical decision-making.

Methods

The PubMed database was accessed programmatically to find papers relating to Virtual Patients. The returned citations were classified and the relevant full text articles were reviewed to find Virtual Patient systems that used electronic health records to create learning modalities.

Results

A total of n = 362 citations were found on PubMed and subsequently classified, of which n = 28 full-text articles were reviewed. Few articles used unformatted electronic health records other than patient CT or MRI scans. The use of patient data, extracted from electronic health records or otherwise, is widespread. The use of unformatted electronic health records in their raw form is less frequent. Patient data use is broad and spans several areas, such as teaching, training, 3D visualisation, and assessment.

Conclusions

Virtual Patients that are based on real patient data are widespread, yet the use of unformatted electronic health records, abundant in hospital information systems, is reported less often. The majority of teaching systems use reformatted patient data gathered from electronic health records, and do not use these electronic health records directly. Furthermore, many systems were found that used patient data in the form of CT or MRI scans. Much potential research exists regarding the use of unformatted electronic health records for the creation of Virtual Patients.

Interactive development of a CT-based tissue model for ultrasound simulation

The objective of this study was to make an interactive method for development of a tissue model, based on anatomical information in computed tomography (CT) images, for use in an ultrasound simulator for training or surgical pre-planning. The method consisted of (1) comparison of true ultrasound B-mode images with corresponding ultrasound-like images, and (2) modification of tissue properties to decrease the difference between these images. Ultrasound-like images that reproduced many, but not all the properties of corresponding true ultrasound images were generated. The tissue model could be used for real-time simulation of ultrasound-like B-mode images on a moderately priced computer.

Efficiency of ultrasound training simulators: method for assessing image realism

Although ultrasound has become an important imaging modality within several medical professions, the benefit of ultrasound depends to some degree on the skills of the person operating the probe and interpreting the image. For some applications, the possibility to educate operators in a clinical setting is limited, and the use of training simulators is considered an alternative approach for learning basic skills. To ensure the quality of simulator-based training, it is important to produce simulated ultrasound images that resemble true images to a sufficient degree. This article describes a method that allows corresponding true and simulated ultrasound images to be generated and displayed side by side in real time, thus facilitating an interactive evaluation of ultrasound simulators in terms of image resemblance, real-time characteristics and man-machine interaction. The proposed method could be used to study the realism of ultrasound simulators and how this realism affects the quality of training, as well as being a valuable tool in the development of simulation algorithms.

B-mode ultrasound image simulation in deformable 3-D medium

This paper presents an algorithm for fast image synthesis inside deformed volumes. Given the node displacements of a mesh and a reference 3-D image dataset of a predeformed volume, the method first maps the image pixels that need to be synthesized from the deformed configuration to the nominal predeformed configuration, where the pixel intensities are obtained easily through interpolation in the regular-grid structure of the reference voxel volume. This mapping requires the identification of the mesh element enclosing each pixel for every image frame. To accelerate this point location operation, a fast method of projecting the deformed mesh on image pixels is introduced in this paper. The method presented was implemented for ultrasound B-mode image simulation of a synthetic tissue phantom. The phantom deformation as a result of ultrasound probe motion was modeled using the finite element method. Experimental images of the phantom under deformation were then compared with the corresponding synthesized images using sum of squared differences and mutual information metrics. Both this quantitative comparison and a qualitative assessment show that realistic images can be synthesized using the proposed technique. An ultrasound examination system was also implemented to demonstrate that real-time image synthesis with the proposed technique can be successfully integrated into a haptic simulation.

Visualization and GPU-accelerated simulation of medical ultrasound from CT images

We present a fast GPU-based method for simulation of ultrasound images from volumetric CT scans and their visualization. The method uses a ray-based model of the ultrasound to generate view-dependent ultrasonic effects such as occlusions, large-scale reflections and attenuation combined with speckle patterns derived from pre-processing the CT image using a wave-based model of ultrasound propagation in soft tissue. The main applications of the method are ultrasound training and registration of ultrasound and CT images.

Clinical Simulation in Modern Teaching and Training of Sonography in Obstetrics and Gynecology

Advances in computer technology, hardware and software have made ultrasound a diagnostic imaging technique of choice in certain areas of medicine or specialties such as obstetrics and gynecology. In teaching and training of obs/gyne ultrasonography, medical educators can utilize different forms of clinical simulators: traditional standardized patients and standard ultrasound diagnostic equipment, computer-based simulators, ultrasound simulators or ultrasound simulators with manikins. The popularity of a simulator is determined not only by its features, ease of use and cost, but also by its available learning modules and applications.

Technology in ultrasound and computers are rapidly advancing in enhancing the quality and miniaturizing ultrasound machines. Portable and handheld ultrasound equipments are quickly becoming indispensable diagnostic instruments in different health care settings especially the emergency rooms and physician offices. Concerns, however, remain related to the lack of competence of health care providers in using and interpreting results of ultrasound studies, and the needs to standardize the training in ultrasonography. It is important to have access to one or more ultrasound simulators; however, it is even more important to establish and integrate fundamental structure of training ultrasonography into the main training curriculum of undergraduate, graduate, and postgraduate medical education.

Ultra-sonografia virtual: reprodutibilidade intra-observador

OBJETIVO: Analisar a reprodutibilidade intra-observador da ultra-sonografia tridimensional (US3D) real com a US virtual, nas modalidades multiplanar e volumétrica. MATERIAIS E MÉTODOS: Foram examinados, prospectivamente, 132 blocos provenientes de 44 avaliações de 26 conceptos. Dezoito conceptos tinham idade gestacional ecográfica de oito semanas a oito semanas e seis dias, e 26 tinham de dez semanas a dez semanas e seis dias. Realizou-se a US3D, analisando-se: comprimento cabeça-nádega, saco gestacional, saco amniótico, translucência nucal, conduto onfalomesentérico, vesícula vitelínica, membros superiores, membros inferiores, distinção cabeça-tórax, perfil da face, coronal da face, implantação das orelhas, perfil da coluna, coronal da coluna, parede abdominal fechada. Foram obtidos três blocos por concepto para posterior realização da US virtual. A análise estatística foi feita utilizando-se o teste t de Student, o teste de McNemar e o kappa. RESULTADOS: No grupo I, a avaliação ultra-sonográfica 3D real multiplanar versus 3D virtual multiplanar, na análise das variáveis contínuas, evidenciou diferença significativa para todas. Na avaliação das variáveis categóricas, evidenciou-se que todas não apresentaram diferença significativa. No grupo II, a avaliação ultra-sonográfica 3D real volumétrica versus 3D virtual volumétrica demonstrou diferença significativa apenas para a variável implantação de orelhas. Os resultados das análises das variáveis categóricas evidenciaram concordância para a maioria das variáveis analisadas em ambos os grupos. CONCLUSÃO: Há reprodutibilidade intra-observador da US3D com a modalidade virtual, multiplanar e volumétrica.

Abdominal virtual ultrasonographic images reconstructed by multi-detector row helical computed tomography

BACKGROUND

Three-dimensional (3D) images can be generated using thin sections from multi-detector row computed tomography (CT) and computer software, simulating images obtained using conventional ultrasonography (US). This software allows easy diagnosis of abdominal lesions and subsequent treatment of focal liver lesions such as hepatocellular carcinoma (HCC). The present study used newly developed virtual US software for diagnose and treatment of hepatobiliary disease.

METHODS

The software was used to create virtual US images in 10 subjects. Radiofrequency ablation (RFA) was performed by virtual US in seven patients with HCC.

RESULTS

Slices were easily reconstructed from various angles, and each slice was continuously animated as with conventional US in all subjects. Moreover, when seven patients with HCC were examined using virtual US, HCC nodules were visualized and could be treated with RFA.

CONCLUSIONS

Virtual US should prove useful for visualization of HCC nodules that cannot be seen under conventional US. Virtual US is a useful tool for US-guided treatment of HCC.

Ultrasound simulators: experience with the SonoTrainer and comparative review of other training systems

Ultrasound has become indispensable in prenatal diagnosis. Ultrasound training, however, still lacks proper quality assessment and control. Moreover, most fetal anomalies which must be diagnosed during pregnancy are extremely rare. Ultrasound simulators could provide an opportunity to overcome this dilemma. This review summarizes the potential benefits of simulator-based ultrasound training, briefly describes the properties of a variety of ultrasound simulators that have been developed for various applications including prenatal diagnosis, and presents the SonoTrainer sonography simulation system which makes it possible to run a real-time simulation of a complete prenatal ultrasound examination. We evaluated the system for the training of first- and second-trimester screening for both normal and pathological findings and found that physicians who received theoretical training and were additionally trained with the simulator (T + S) significantly improved their skills in measurements of nuchal translucency thickness (NT) and crown-rump length (CRL) as compared with colleagues who only underwent theoretical instruction (T) [mean +/- SD NT deviation: 0.31 +/- 0.1 mm (T + S) vs. 0.62 +/- 0.2 mm (T), P < 0.05; mean +/- SD CRL deviation: 1.48 +/- 2.0 mm (T + S) vs. 3.27 +/- 2.5 (T), P < 0.05]. Simulator-based training enabled physicians to diagnose rare fetal anomalies in the second trimester with a sensitivity of 86% and a specificity of 100%. In a study in which second-trimester scans including fetal anomalies were presented to physicians, 96% of the participants subjectively estimated their training effect as being good. We therefore conclude that simulator-based training would provide an ideal educational tool to test, improve and monitor a physician's or technician's ultrasound skills in detecting fetal anomalies.