J Med Syst (2016) 40:158 DOI 10.1007/s10916-016-0522-5

EDUCATION & TRAINING

Anatomical-Ultrasound Visor for Regional Anaesthesia Juan A. Juanes 1 & Pablo Alonso 2 & Felipe Hernández 2 & Pablo Ruisoto 3,4 & Clemente Muriel 2

Received: 16 November 2015 / Accepted: 9 May 2016 # Springer Science+Business Media New York 2016

Abstract Introduction. Regions considered optimal for performing peripheral nerve blocking have been well documented. However identify and perform regional anesthesia in those regions from ultrasound images remains a challenge. Aim. This study aims to develop a virtual environment for the simulation of ultrasound exploration of the neck nerves and both the upper and lower limbs for regional anesthesia. Method. Cross-sectional images were obtained from Magnetic Resonance Imaging for puncture regions involved in ultrasound-guided nerve block. Results. A threedimensional digital viewer was developed for the anatomical and ultrasound identification of key structures involved in peripheral nerve block in neck, upper and lower limbs. Conclusion. This study provides a virtual environment software used to simulate ultrasound exploration of nerve neck and upper and lower limbs for regional anesthesia. Discussion. Potential implications of this tool for improving the ultrasound exploration for regional anesthesia and acquisition of anatomical knowledge are further discussed.

This article is part of the Topical Collection on Education & Training * Pablo Ruisoto [email protected]

1

Department of Human Anatomy, Faculty of Medicine, University of Salamanca, Salamanca, Spain

2

Department of Anesthesia and Pain Therapy, Universitary Hospital, Salamanca, Spain

3

VisualMed System Research Group, University of Salamanca, Avda. De la Merced, 109/131, Salamanca, Spain

4

European University of Madrid, calle Tajo, s/n. Villaviciosa de Odon, Madrid, Spain

Keywords Anesthesia . Medical training . Software . Anatomy . Ultrasonography

Introduction Regional anesthesia with ultrasound has awakened deep interest in the past 10 years and is now a common practice for many anesthesiologists [1–4]. In fact, ultrasound guidance is considered as one of the most important evolutions in the field of regional anesthesia techniques, in particular, for peripheral nerve blocks and regional anesthesia [5, 6], by which the regional anesthesiologist can attain the safety, speed, and efficacy of general anesthesia [7, 8]. However, traditional training methods based on face-to-face lectures and consultation of printed learning material requires a prolonged learning curve. Currently, digital learning material provides new learning and teaching opportunities including internet-based learning such as Open University Courses, letting students access multimedia contents in an interactive and personalized way [9]. Two of the main applications within the frame of elearning are the development of simulators and virtual reality scenarios. Simulators allow the exploration of a virtual patient, allowing students the acquisition of practical skills without the need to come into contact with a real patient [10]. Indeed, in a review of these new learning techniques it has been reported that methods based on elearning may be as efficient as conventional teaching methods, they tend to have a high degree of satisfaction and are cost-effective [11]. The use of simulators and virtual reality, as part of elearning, allow students to perform explorations on virtual patients, facilitating the acquisition of practical skills without having to use a real patient. These learning materials are known and recommended by the American Society of

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Regional Anesthesia and Pain Medicine/European Society of Regional Anesthesia and Pain Therapy (ASRA/ESRA) as BAdditional Education Resources^ in the field [12, 13]. For training in regional anaesthesia with ultrasound, the acquisition of a series of specific areas of knowledge is crucial. On one hand, students need anatomical knowledge, in particular sectional anatomical knowledge of the zones where blocks are performed, so that they can recognize the different structures and identify the nerves correctly. On the other hand, these concepts can be integrated into a new one denominated sonoanatomy, which are simply the viewing of the body and the identification of structures through the use of ultrasound. Basing our efforts on the new technologies available, the aim of this study is to develop a virtual scenario suitable for teaching and training in regional anesthesia and different types of blockade.

Methodology Image acquisition Original ultrasound images were obtained using a Mylab 25 portable ultrasonograph with a multifrequency probe from 5 to 12 MHz from a right-handed 43 year old healthy male subject. Approval to conduct this study was granted by the appropriate IRB and Helsinki Declaration principles, including informed consent. In addition, original video clips of ultrasound explorations of the nerves of the brachial and lumbosacral plexuses were also created, including video clips with the Doppler color function in the specific block regions and clips of the movement produced by neurostimulation in the different blockades. Fig 1 Transverse section of the upper limb from a cadaver from the Visible Human Project for the manual segmentation of the anatomical bone, muscle and vessel-nerve structures

Original Magnetic Resonances Image were acquired using a Philips Medical Systems device of 1.5 Teslas. The acquisition protocol consisted of sequences of the neck and of the limbs on the axial plane, with the following parameters: Repetition Time = 412; Echo Time = 6.4; Inversion Time = 300; Thickness = 1.6 mm; Slice Spacing =0.8 mm; Matrix =276 × 276; Flip Angle =90°. The images were enhanced in T1. Finally, surface photos of a model serving as a patient and selected regions crossed by the different nerves were acquired. Image processing In order to reconstruct anatomical structures indirectly involved in the process of regional anesthesia, regions of interest (ROIs) were manually segmented from MRI images obtained from the Visible Human Project™. Specifically, images used were high resolution axial sections 1 mm thick with an original 576 × 768 pixel size (Figs 1 and 2). Then, anatomical structures were geometrically modeled and textured using Autodesk Maya version 2011™ and Mental Ray as rendering motor. Anatomical-ultrasound visor development The viewer was developed for Windows and was programmed in Visual C++. The movement of the cursor on the surface of the human anatomy adopted the form of an ultrasound wave, which was synchronized with a projection of the video clip of the ultrasound exploration on the same region. Additionally, International Nomina Anatomica [14] was used as reference for labeling each target structure.

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presented were as follows: item 1) This tool is a completely new product; item 2) The tool is easy to use; item 3) The tool facilitates the learning of regional blockades guided by ultrasound; item 4) It is useful for our daily practice; item 5) The content is similar to what is seen in routine clinical practice; item 6) This tool facilitates the understanding of the anatomy of the limbs; item 7) It is a suitable self-learning method, and item 8) I would recommend it to colleagues and even to anatomy and radiology students. Participants answered in a 5 point Likert-like scale: 1- completely disagree; 2- partially disagree; 3- neither agree nor disagree; 4- partially agree; 5- completely agree.

Results

Fig 2 Geometric modelling, using Autodesk Maya 2011 software, of the anatomical structures previously segmented and identified, for their reconstruction and 3D visualization

Satisfaction and perception of usefulness evaluation Finally, the developed simulator was tested and evaluated by 80 anesthesiologists from different Spanish hospitals using a satisfaction Likert type scale composed of 8 items. The items

Fig 3 Complete screen of the anatomical-ultrasound visor: a) ultrasound of the region being explored; b) Btraffic light^; c) labelled with the nerve block; d) displays; e) photo of the model surface over which the probe is

A fully anatomical-ultrasound viewer for regional anaesthesia was developed (Fig 3). It allowed a complete anatomical assessment of different neuromuscular systems of the upper and lower limbs dependent on the brachial and lumbar plexuses, integrating magnetic res onance radiological and echographical images. The user-friendly interface allows clinician to easily interact with three-dimensional anatomical models previously reconstruction and other elements of the visual scene by placing the cursor on the screen using the mouse. In particular, the following features can be accessed and displayed in the main screen of the application:

passed; f) ultrasound probe; g) three-dimensional anatomical visor; h) displays with anatomical description

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Fig 5 Doppler ultrasound of the zone of interscalene block

Fig 4 Representation of the 3D anatomical visor, showing the hierarchical tree for the assessment and study of the different neuromuscular systems. The anatomical structures of the visor can be observed, in any spatial position, by moving the cursor

First, an atlas of ultrasound anatomy where by moving the cursor over an ultrasound image, for example of the plexus, it is possible to identify and perform spatial rotations, translations, and applying zoom effect in and out for less or more detailed visualization of hierarchically organized anatomical structures (Fig 4). Second, a video clip with Doppler color of the specific zone (Fig 5). Third, a video clip with the neurostimulation produced at that level (Fig 6). Next, a magnetic resonance section with the structures identified (Fig 7). Finally, a technical document about the concepts involved in ultrasonography and its applications in regional anesthesia and the different types of blockades. The user must first choose from a given group of blocks, established on the basis of a photo that appears on screen. For example, user can be given a photo of the neck and upper

Fig 6 Video Image of neurostimulation of the interscalene brachial plexus

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Fig 7 MRI section with the structures of the neck profiled in the zone of interscalene brachial plexus block

chest of the model patient, and the regions that can be explored will be those corresponding to supraclavicular, medial infraclavicular and coracoid interscalene block. A blue mark would indicate the orientation of the probe. By using the mouse and left clicking, it is possible to Bpick up^ the probe and move it over the photo. When a nerve is reached, an ultrasound image of that region is shown, which moves with the movement of the mouse (probe). If the probe is not positioned correctly, it will not provide an ultrasound image and a red Btraffic light^ comes on. If the nerve has been reached the light turns to amber, and if the correct region for the blockade to be done has been reached it turns green and a signal appears with the block that can be performed; for example, an interscalene block (Figs 8 and 9). To summarize, the user can visualize an ultrasound image of the region where the different anatomical structures are located and by means of an intuitive Btraffic light^, learns the most appropriate region for performing a block. It should be noted that the use of ultrasound permits a block along the whole nerve tract. Nevertheless, we chose the regions traditionally mentioned in the literature for performing blocks with ultrasound. Evaluation Anaesthesiologists reported a very high degree of satisfaction with the application for both clinical and professional training purposes. In particular, participants scored every item significantly above 4.5, where 4 was, Bpartially agree^ and 5 was Bcompletely agree^. Scores fell at 4.7 points average, the medical specialists considered this simulator a useful tool to facilitate the learning of regional blockades guided by ultrasound

in addition to their daily practice. They considered the content similar to what is seen in routine clinical practice and useful to facilitate the understanding of the anatomy of the limbs. They would also recommend it to their colleagues including anatomy or radiology students.

Discusion In summary, this study provides a virtual environment software used to simulate ultrasound exploration of nerve neck and upper and lower limbs for regional anesthesia. For training in regional anesthesia with ultrasound, the acquisition of a series of specific areas of knowledge is crucial. On the one hand, students need anatomical knowledge, especially sectional anatomical knowledge of the regions where blocks are performed, so that they can recognize the different structures and identify the nerves correctly. On the other hand, these concepts can be integrated into a new one denominated sonoanatomy, which is simply the viewing of the body and the identification of structures through the use of ultrasound. Using new technologies, we have created a simulator for the learning of regional anesthesia with ultrasound. In this platform we include several e-learning concepts. First, there is a three dimensional virtual environment with which users can interact to learn about different aspects of anatomy. Here, MRI sections of the different anatomical regions where nerve blocks should be performed are included. Second, the application includes a simulator of ultrasound exploration of the

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Fig 8 Ultrasound exploration of the brachial plexus of the neck. A) amber traffic light; b) ultrasound of the brachial plexus (between the supraclavicular and interscalene zone); c) ultrasound probe in the neck

neck, the upper and lower limbs where users can follow the nerves in real time, including the best one for performing the

block. Finally, students have an array of documents concerning the basic concepts of ultrasonography and its

Fig 9 Ultrasound exploration of the brachial plexus in the neck. A) green traffic light; b) ultrasound image of the interscalene plexus; c) probe correctly placed

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application in regional anesthesia and specific considerations about the different blocks. However, like any technique used in anesthesiology, specific training is required and the learning period tends to be prolonged. Traditional ways of learning include face to face teaching and the reading of written material. Together with these traditional methods, the so called e-learning methods are increasingly used; these encompass learning based on the internet, on-line learning, distance learning, and computer-assisted learning, where through the use of multimedia systems students can interact with the material and learn on an individual basis. Although the learning of regional anesthesia with ultrasound necessarily involves practical use of an ultrasound device, with this platform we offer the user a complete system for acquiring knowledge in this specialty. By doing this, we expect to reduce learning time in comparison with learning with real patients, thus avoiding unnecessary discomfort. Evidently, the learning of regional anesthesia with ultrasound necessarily requires the use of a real ultrasound device. The movement sensation of the probe such as rotation and oscillation, or pressure on the patient’s body, and of course the actual implementation of a block, can only be achieved through practice with real patients. Nevertheless, with this tool we offer users a system for them to acquire both anatomical knowledge and expertise in the ultrasound exploration of the nerve tracts of the upper and lower limbs. We also offer practical advice about ultrasonography in regional anesthesia and in the implementation of different types of blocks. It is unquestionable that these basic regions of knowledge offered prior to the actual practicing of ultrasound-guided blocks will decrease the time required for students and professionals to learn the technique. This tool offers noticeable differences with previous applications such as http://www.usra.ca/vspine.php. For example, our viewer allows the probe to be positioned by the user, who must locate the most suitable region on the surface of the virtual patient’s body (real image) where the nerve tracts are. Therefore it is the user who moves the ultrasound probe, allowing greater authenticity to the exploration. The greatest potential of the application lies in its the threedimensional anatomical viewer, which was highly appreciated by the anesthesiologists who used the tool. This 3D anatomical viewer allows users to see each of the anatomical structures in any spatial position, allowing them to remove or replace each of the muscles or nerves as wished, which differs from other website resources where the muscle view is twodimensional and run one-by-one, thus providing clues for better spatial orientation. Additionally, this application includes an interface that allows simultaneous and independent interaction

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with ultrasound image, anatomical image, Doppler echo, neurostimulation and MR axial sections. Moreover, it works off-line by simply installing it as a standalone application. In conclusion, this study provides an innovative simulation environment for the implementation of regional anesthesia and offers a new tool for improving clinical training in anesthesiology. Compliance with ethical standards Conflict of interest The authors declare that they have no conflict of interest.

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