Electrical impedance tomography (EIT) is an imaging method that can be used to image electrical impedance contrasts within various tissues of the body. To support development of EIT measurement ...systems, a phantom is required that represents the electrical characteristics of the imaging domain. No existing type of EIT phantom combines good performance in all three characteristics of resistivity resolution, spatial resolution, and stability. Here, a novel EIT phantom concept is proposed that uses 3D printed conductive material. Resistivity is controlled using the 3D printing infill percentage parameter, allowing arbitrary resistivity contrasts within the domain to be manufactured automatically. The concept of controlling resistivity through infill percentage is validated, and the manufacturing accuracy is quantified. A method for making electrical connections to the 3D printed material is developed. Finally, a prototype phantom is printed, and a sample EIT analysis is performed. The resulting phantom, printed with an Ultimaker S3, has high reported spatial resolution of 6.9 µm, 6.9 µm, and 2.5 µm for X, Y, and Z axis directions, respectively (X and Y being the horizontal axes, and Z the vertical). The number of resistivity levels that are manufacturable by varying infill percentage is 15 (calculated by dividing the available range of resistivities by two times the standard deviation of the manufacturing accuracy). This phantom construction technique will allow assessment of the performance of EIT devices under realistic physiological scenarios.
The Physiome Model Repository 2 YU, Tommy; LLOYD, Catherine M; NIELSEN, Poul M. F ...
Bioinformatics (Oxford, England),
03/2011, Letnik:
27, Številka:
5
Journal Article
Recenzirano
The Physiome Model Repository 2 (PMR2) software was created as part of the IUPS Physiome Project (Hunter and Borg, 2003), and today it serves as the foundation for the CellML model repository. Key ...advantages brought to the end user by PMR2 include: facilities for model exchange, enhanced collaboration and a detailed change history for each model.
PMR2 is available under an open source license at http://www.cellml.org/tools/pmr/; a fully functional instance of this software can be accessed at http://models.physiomeproject.org/.
Jet injection presents a promising alternative to needle and syringe injection for transdermal drug delivery. The controllability of recently-developed jet injection devices now allows jet speed to ...be modulated during delivery, and has enabled efficient and accurate delivery of volumes up to 0.3 mL. However, recent attempts to inject larger volumes of up to 1 mL using the same methods have highlighted the different requirements for successful delivery at these larger volumes. This study aims to establish the jet speed requirements for delivery of 1 mL of liquid using a controllable, voice coil driven injection device. Additionally, the effectiveness of a two-phase jet speed profile is explored (where jet speed is deliberately decreased toward the end of the injection) and compared to the constant jet speed case.
A controllable jet injection device was developed to deliver volumes of 1 mL of liquid at jet speeds >140 m/s. This device was used to deliver a series of injections into post-mortem porcine tissue in single and two-phase jet speed profiles. Single-phase injections were performed over the range 80 m/s to 140 m/s. Consistent delivery success (>80% of the liquid delivered) was observed at a jet speed of 130 m/s or greater. Consistent penetration into the muscle layer coincided with delivery success. Two-phase injections of 1 mL were performed with a first phase volume of 0.15 mL, delivered at 140 m/s, while the injection of the remainder of fluid was delivered at a second phase speed that was varied over the range 60 m/s to 120 m/s. Ten two-phase injections were performed with a second phase speed of 100 m/s producing a mean delivery volume of 0.8 mL ± 0.2 mL, while the single-phase injections at 100 m/s achieved a mean delivery volume of 0.4 mL ± 0.3 mL. These results demonstrate that a reduced jet speed can be used in the later stages of a 1 mL injection to achieve delivery success at a reduced energy cost. We found that a jet speed approaching 100 m/s was required following initial penetration to successfully deliver 1 mL, whereas speeds as low as 50 m/s have been used for volumes of <0.3 mL. These findings provide valuable insight into the effect of injection volume and speed on delivery success; this information is particularly useful for devices that have the ability to vary jet speed during drug delivery.
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•The jet injection of 1 mL required a greater jet speed later in the injection than that reported for volumes ≤0.3 mL.•A two-phase jet speed profile successfully delivered 1 mL at a reduced energy cost relative to single-speed injections.•Subcutaneous injections demonstrated a correlation between the volume delivered and the penetration depth.
Computer vision and image processing algorithms form essential components of many industrial, medical, commercial, and research-related applications. Modern imaging systems provide high resolution ...images at high frame rates, and are often required to perform complex computations to process image data. However, in many applications rapid processing is required, or it is important to minimise delays for analysis results. In these applications, central processing units (CPUs) are inadequate, as they cannot perform the calculations with sufficient speed. To reduce the computation time, algorithms can be implemented in hardware accelerators such as digital signal processors (DSPs), field-programmable gate arrays (FPGAs), and graphics processing units (GPUs). However, the selection of a suitable hardware accelerator for a specific application is challenging. Numerous families of DSPs, FPGAs, and GPUs are available, and the technical differences between various hardware accelerators make comparisons difficult. It is also important to know what speed can be achieved using a specific hardware accelerator for a particular algorithm, as the choice of hardware accelerator may depend on both the algorithm and the application. The technical details of hardware accelerators and their performance have been discussed in previous publications. However, there are limitations in many of these presentations, including: inadequate technical details to enable selection of a suitable hardware accelerator; comparisons of hardware accelerators at two different technological levels; and discussion of old technologies.
To address these issues, we introduce and discuss important considerations when selecting suitable hardware accelerators for computer vision and image processing tasks, and present a comprehensive review of hardware accelerators. We discuss the practical details of chip architectures, available tools and utilities, development time, and the relative advantages and disadvantages of using DSPs, FPGAs, and GPUs. We provide practical information about state-of-the-art DSPs, FPGAs, and GPUs as well as examples from the literature. Our goal is to enable developers to make a comprehensive comparison between various hardware accelerators, and to select a hardware accelerator that is most suitable for their specific application.
•Important considerations when selecting hardware accelerators are discussed.•Practical information about state-of-the-art DSPs, FPGAs, and GPUs are presented.•Relative advantages and disadvantages of DSPs, FPGAs, and GPUs are explained.•Several recent examples from the literature are reviewed and compared.
Significance: A non-destructive technique for accurately characterizing the spatial distribution of optical properties of soft tissue membranes may give improved outcomes in many tissue engineering ...applications.
Aim: This study aimed to develop a non-destructive macroscopic imaging technique that is sensitive to optical anisotropy, typical of fibrous components in soft tissue membranes, and can address some of the difficulties caused by the complex turbid nature of these tissues.
Approach: A near-infrared Mueller matrix imaging polarimeter employing logarithm decomposition was developed and used to conduct transmission measurements of all the polarization properties across the full thickness of bovine pericardium tissue.
Results: The full Mueller matrix was measured across a 70 mm × 70 mm sample of calf bovine pericardium and revealed significant retardance (linear and circular) and depolarization in this tissue. Regions with a uniform axis of optical anisotropy were identified. Mueller matrix imaging demonstrated that the exhibited circular retardance was sufficient to lead to possible misinterpretation of apparent fiber orientation when using conventional polarization imaging techniques for such tissues.
Conclusions: Mueller matrix imaging can identify regional distributions of optical anisotropy in calf bovine pericardium. This new capability is a promising development in non-destructive imaging for tissue selection.
Objective: To develop a method to quantify strain fields from in vivo intestinal motility recordings that mitigate accumulation of tracking error. Methods: The deforming geometry of the intestine in ...video sequences was modeled by a biquadratic B-spline mesh. Green-Lagrange strain fields were computed to quantify the surface deformations. A nonlinear optimization scheme was applied to mitigate the accumulation of tracking error associated with image registration. Results: The optimization scheme maintained the RMS strain error under 1% and reduced the rate of strain error by 97% during synthetic tests. The algorithm was applied to map 64 segmental, 12 longitudinal, and 23 propagating circular contractions in the jejunum. Coordinated activity of the two muscle layers could be identified and the strain fields were able to map and quantify the anisotropic contractions of the intestine. Frequency and velocity were also quantified, from which two types of propagating circular contractions were identified: (i) <inline-formula><tex-math notation="LaTeX">-\text{0.36}\pm \text{0.04}</tex-math></inline-formula> strain contractions that originated spontaneously and propagated at <inline-formula><tex-math notation="LaTeX">\text{3} \pm \text{1}</tex-math></inline-formula> mm/s in two pigs, and (ii) cyclic propagating contractions of <inline-formula><tex-math notation="LaTeX">-\text{0.17} \pm \text{0.02}</tex-math></inline-formula> strain occurred at <inline-formula><tex-math notation="LaTeX">\text{11.0} \pm \text{0.6}</tex-math></inline-formula> cpm and propagated at <inline-formula><tex-math notation="LaTeX">\text{16} \pm \text{4}</tex-math></inline-formula> mm/s in a rabbit. Conclusion: The algorithm simultaneously mapped the circular, longitudinal activity of the intestine with high spatial resolution and quantified anisotropic contractions and relaxations. Significance: The proposed algorithm can now be used to define the interactions of muscle layers during motility patterns. It can be integrated with high-resolution bioelectrical recordings to investigate the regulatory mechanisms of motility.
Aim
Physiotherapists typically use digital palpation to determine residual tension in a muscle, referred to as muscle stiffness or tone. These assessments are subjective, and little is known about ...their accuracy or repeatability. Despite this, it is standard practice to base clinical treatment on these findings. The aim of this study was to assess physiotherapists’ ability to assign a seven‐point palpation scale to quantitative stiffness values generated by a novel device.
Methods
Prospective observational study involving 125 musculoskeletal and pelvic floor physiotherapists. A novel device was developed that replicates the haptic feedback that clinicians assess as muscle stiffness. Measurements of displacement, force, and stiffness were recorded.
Results
There was wide overlap between each scale category assigned to the stiffness values, from low stiffness at −3 (119 106, 132 N/m) to moderate stiffness at 0 (462 435,489 N/m); to high stiffness at +3 (897 881,913 N/m). Consistency in applying the scale was poor, and the probability of a similar value of stiffness being assigned to the same scale category by different participants was low.
Conclusions
While palpation is used globally by physiotherapists as a readily available and low‐cost method of assessing muscle stiffness, these results indicate that it should be used with caution in diagnosing and defining patient care. Clinical assessment of muscle stiffness requires a validated and reliable palpation scale if this metric is to be used to diagnose pathology and develop treatment protocols. Training in this scale should then be recommended to improve reliability in patient assessment.
Introduction and hypothesis
The impact of surgery on pelvic floor muscle (PFM) function remains uncertain. There is a pressure differential along the length of the vagina, influenced by surrounding ...active and passive tissue structures, giving rise to a pressure profile. The aim of this study is to determine if an intravaginal pressure sensor, femfit®, can measure differences in pressure profiles before and after surgery for pelvic organ prolapse (POP).
Methods
This pilot study includes 22 women undergoing POP surgery. Intravaginal pressure profiles were measured with femfit® pre- and post-surgery and differences tested using paired Student’s
t
-tests. Patients completed validated questionnaires for vaginal, bowel, and urinary incontinence symptoms pre- and post-POP surgery and a femfit® usability questionnaire.
Results
Sixteen sets of vaginal pressure data were analysed. The highest pressure generated was identified as the peak PFM pressure, whilst all sensor measurements provided a pressure profile. Intra-abdominal pressure (IAP) was measured by the most distal sensor, 8. On average, the difference between peak PFM pressure and IAP was significantly greater post-surgery (
p
< 0.01). Urinary and vaginal symptom questionnaire scores were significantly improved after POP surgery. Femfit® usability questionnaires demonstrated high levels of patient acceptability.
Conclusions
Women generate higher peak PFM pressures compared to IAP post-POP surgery, with pressure profiles that are comparable to women without POP. This metric might be useful to assess the outcome of POP surgery and encourage women to maintain this profile via PFM training, potentially reducing POP recurrence risk.
This title provides an opportunity for computational biomechanics specialists to present and exchange opinions on the opportunities of applying their techniques to computer-integrated medicine.
One of the greatest challenges for mechanists is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, biomedical sciences, and ...medicine. The proposed workshop will provide an opportunity for computational biomechanics specialists to present and exchange opinions on the opportunities of applying their techniques to computer-integrated medicine. These are peer-reviewed proceedings of the workshop affiliated to a major international research conference (Medical Image Computing and Computer Assisted Intervention MICCAI 2010 in Beijing) dedicated to research in the field of medical image computing and computer assisted medical interventions. The list of subjects covered include: medical image analysis, image-guided surgery, surgical simulation, surgical intervention planning, disease prognosis and diagnostics, injury mechanism analysis, implant and prostheses design, medical robotics.
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