Phantom study of an ultrasound guidance system for transcatheter aortic valve implantation

McLeod, A. Jonathan; Currie, Morgan; Moore, John; Bainbridge, Daniel; Kiaii, Bob; Chu, Michael; Peters, Terry M.

doi:10.1016/j.compmedimag.2014.12.001

Cited by 8 publications

(6 citation statements)

References 14 publications

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“…Many TMMs have been proposed for ultrasound phantoms (Madsen et al 2005 , Zell et al 2007 , Troia et al 2017 ), but there is a need for new materials, and new methods to use them in phantoms. Currently-used TMMs include silicone (McLeod et al 2016 ), agar/gelatin (Pavan et al 2010 ), poly(vinyl alcohol) cryogel (Surry et al 2004 , Xia et al 2011 ), polyvinyl chloride-plastisol (McLeod et al 2015 ), and urethane rubber (Culjat et al 2010 ). Identifying a TMM that allows for independent tuning of parameters such as the speed of sound, ultrasonic scattering, and attenuation, and which can be developed from non-toxic, mechanically robust, and inexpensive materials, has been particularly challenging.…”

Section: Introductionmentioning

confidence: 99%

Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds

et al. 2018

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Here we describe methods for creating tissue-mimicking ultrasound phantoms based on patient anatomy using a soft material called gel wax. To recreate acoustically realistic tissue properties, two additives to gel wax were considered: paraffin wax to increase acoustic attenuation, and solid glass spheres to increase backscattering. The frequency dependence of ultrasound attenuation was well described with a power law over the measured range of 3–10 MHz. With the addition of paraffin wax in concentrations of 0 to 8 w/w%, attenuation varied from 0.72 to 2.91 dB cm−1 at 3 MHz and from 6.84 to 26.63 dB cm−1 at 10 MHz. With solid glass sphere concentrations in the range of 0.025–0.9 w/w%, acoustic backscattering consistent with a wide range of ultrasonic appearances was achieved. Native gel wax maintained its integrity during compressive deformations up to 60%; its Young’s modulus was 17.4 ± 1.4 kPa. The gel wax with additives was shaped by melting and pouring it into 3D printed moulds. Three different phantoms were constructed: a nerve and vessel phantom for peripheral nerve blocks, a heart atrium phantom, and a placental phantom for minimally-invasive fetal interventions. In the first, nerves and vessels were represented as hyperechoic and hypoechoic tubular structures, respectively, in a homogeneous background. The second phantom comprised atria derived from an MRI scan of a patient with an intervening septum and adjoining vena cavae. The third comprised the chorionic surface of a placenta with superficial fetal vessels derived from an image of a post-partum human placenta. Gel wax is a material with widely tuneable ultrasound properties and mechanical characteristics that are well suited for creating patient-specific ultrasound phantoms in several clinical disciplines.

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Section: Introductionmentioning

confidence: 99%

Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds

et al. 2018

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“…Specifically, surgical simulators that use patient-specific or realistic anatomy could offer a safe and comprehensive training experience for new or inexperienced clinicians. [17][18][19] They can also be used to validate new surgical tools or image guidance techniques while in the development stage, [20][21][22] helping to reduce the need for animal trials. Finally, they allow for the simulation of a surgical procedure preoperatively, using different tools and techniques to evaluate each method's efficacy for the patient.…”

Section: Introductionmentioning

confidence: 99%

Patient-specific cardiac phantom for clinical training and preprocedure surgical planning

et al. 2018

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Minimally invasive mitral valve repair procedures including MitraClip are becoming increasingly common. For cases of complex or diseased anatomy, clinicians may benefit from using a patient-specific cardiac phantom for training, surgical planning, and the validation of devices or techniques. An imaging compatible cardiac phantom was developed to simulate a MitraClip procedure. The phantom contained a patient-specific cardiac model manufactured using tissue mimicking materials. To evaluate accuracy, the patient-specific model was imaged using computed tomography (CT), segmented, and the resulting point cloud dataset was compared using absolute distance to the original patient data. The result, when comparing the molded model point cloud to the original dataset, resulted in a maximum Euclidean distance error of 7.7 mm, an average error of 0.98 mm, and a standard deviation of 0.91 mm. The phantom was validated using a MitraClip device to ensure anatomical features and tools are identifiable under image guidance. Patient-specific cardiac phantoms may allow for surgical complications to be accounted for preoperative planning. The information gained by clinicians involved in planning and performing the procedure should lead to shorter procedural times and better outcomes for patients.

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“…The data reported in the TAVI Deployment With Fluoroscopic or AR Guidance experiment were also presented in McLeod et al 24 The previous work focused on the design of guidance systems and specialized delivery tools from an engineering perspective, whereas this article provides more clinical context and evaluation of aspects of the surgical workflow, such as valve localization, which are needed to advance this work into the operating room.…”

Section: Transcatheter Aortic Valve Implantation Deployment With Fluomentioning

confidence: 97%

Augmented Reality System for Ultrasound Guidance of Transcatheter Aortic Valve Implantation

Currie

McLeod

Moore

et al. 2016

Innovations�(Phila)

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Objective Transcatheter aortic valve implantation (TAVI) relies on fluoroscopy and nephrotoxic contrast medium for valve deployment. We propose an alternative guidance system using augmented reality (AR) and transesophageal echocardiography (TEE) to guide TAVI deployment. The goals of this study were to determine how consistently the aortic valve annulus is defined from TEE using different aortic valve landmarks and to compare AR guidance with fluoroscopic guidance of TAVI deployment in an aortic root model. Methods Magnetic tracking sensors were integrated into the TAVI catheter and TEE probe, allowing these tools to be displayed in an AR environment. Variability in identifying aortic valve commissures and cuspal nadirs was assessed using TEE aortic root images. To compare AR guidance of TAVI deployment with fluoroscopic guidance, a TAVI stent was deployed 10 times in the aortic root model using each of the two guidance systems. Results Commissures and nadirs were both investigated as features for defining the valve annulus in the AR guidance system. The commissures were identified more consistently than the nadirs, with intraobserver variability of 2.2 and 3.8 mm, respectively, and interobserver variability of 3.3 and 4.7 mm, respectively. The precision of TAVI deployment using fluoroscopic guidance was 3.4 mm, whereas the precision of AR guidance was 2.9 mm, and its overall accuracy was 3.4 mm. This indicates that both have similar performance. Conclusions Aortic valve commissures can be identified more reliably than cuspal nadirs from TEE. The AR guidance system achieved similar deployment accuracy to that of fluoroscopy while eliminating the use and consequences of nephrotoxic contrast and radiation.

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Phantom study of an ultrasound guidance system for transcatheter aortic valve implantation

Cited by 8 publications

References 14 publications

Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds

Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds

Patient-specific cardiac phantom for clinical training and preprocedure surgical planning

Augmented Reality System for Ultrasound Guidance of Transcatheter Aortic Valve Implantation

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