Fast catheter segmentation and tracking based on x-ray fluoroscopic and echocardiographic modalities for catheter-based cardiac minimally invasive interventions

X-ray fluoroscopy and echocardiography imaging (ultrasound, US) are two imaging modalities that are widely used in cardiac catheterization. For these modalities, a fast, accurate and stable algorithm for the detection and tracking of catheters is required to allow clinicians to observe the catheter location in real-time. Currently X-ray fluoroscopy is routinely used as the standard modality in catheter ablation interventions. However, it lacks the ability to visualize soft tissue and uses harmful radiation. US does not have these limitations but often contains acoustic artifacts and has a small field of view. These make the detection and tracking of the catheter in US very challenging. The first contribution in this thesis is a framework which combines Kalman filter and discrete optimization for multiple catheter segmentation and tracking in X-ray images. Kalman filter is used to identify the whole catheter from a single point detected on the catheter in the first frame of a sequence of x-ray images. An energy-based formulation is developed that can be used to track the catheters in the following frames. We also propose a discrete optimization for minimizing the energy function in each frame of the X-ray image sequence. Our approach is robust to tangential motion of the catheter and combines the tubular and salient feature measurements into a single robust and efficient framework. The second contribution is an algorithm for catheter extraction in 3D ultrasound images based on (a) the registration between the X-ray and ultrasound images and (b) the segmentation of the catheter in X-ray images. The search space for the catheter extraction in the ultrasound images is constrained to lie on or close to a curved surface in the ultrasound volume. The curved surface corresponds to the back-projection of the extracted catheter from the X-ray image to the ultrasound volume. Blob-like features are detected in the US images and organized in a graphical model. The extracted catheter is modelled as the optimal path in this graphical model. Both contributions allow the use of ultrasound imaging for the improved visualization of soft tissue. However, X-ray imaging is still required for each ultrasound frame and the amount of X-ray exposure has not been reduced. The final contribution in this thesis is a system that can track the catheter in ultrasound volumes automatically without the need for X-ray imaging during the tracking. Instead X-ray imaging is only required for the system initialization and for recovery from tracking failures. This allows a significant reduction in the amount of X-ray exposure for patient and clinicians.Open Acces

Investigation of mobile devices usage and mobile augmented reality applications among older people

Mobile devices such as tablets and smartphones have allow users to communicate, entertainment, access information and perform productivity. However, older people are having issues to utilise mobile devices that may affect their quality of life and wellbeing. There are some potentials of mobile Augmented Reality (AR) applications to increase older users mobile usage by enhancing their experience and learning. The study aims to investigate mobile devices potential barriers and influence factors in using mobile devices. It also seeks to understand older people issues in using AR applications

Atherosclerosis: Methods and Protocols

This volume provides detailed, up-to-date methods used in research on Atherosclerosis. Chapters guide readers through an overview of the pathogenesis of atherosclerosis and model systems together with in vitro, ex vivo, in vivo and emerging methods in atherosclerosis research. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and cutting-edge, Atherosclerosis: Methods and Protocols serves as an invaluable resource for those engaging in research on atherosclerosis and cardiovascular disease, as well as for researchers who are new to t

PRELIMINARY FINDINGS OF A POTENZIATED PIEZOSURGERGICAL DEVICE AT THE RABBIT SKULL

The number of available ultrasonic osteotomes has remarkably increased. In vitro and in vivo studies have revealed differences between conventional osteotomes, such as rotating or sawing devices, and ultrasound-supported osteotomes (Piezosurgery®) regarding the micromorphology and roughness values of osteotomized bone surfaces. Objective: the present study compares the micro-morphologies and roughness values of osteotomized bone surfaces after the application of rotating and sawing devices, Piezosurgery Medical® and Piezosurgery Medical New Generation Powerful Handpiece. Methods: Fresh, standard-sized bony samples were taken from a rabbit skull using the following osteotomes: rotating and sawing devices, Piezosurgery Medical® and a Piezosurgery Medical New Generation Powerful Handpiece. The required duration of time for each osteotomy was recorded. Micromorphologies and roughness values to characterize the bone surfaces following the different osteotomy methods were described. The prepared surfaces were examined via light microscopy, environmental surface electron microscopy (ESEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and atomic force microscopy. The selective cutting of mineralized tissues while preserving adjacent soft tissue (dura mater and nervous tissue) was studied. Bone necrosis of the osteotomy sites and the vitality of the osteocytes near the sectional plane were investigated, as well as the proportion of apoptosis or cell degeneration. Results and Conclusions: The potential positive effects on bone healing and reossification associated with different devices were evaluated and the comparative analysis among the different devices used was performed, in order to determine the best osteotomes to be employed during cranio-facial surgery

Muscle activation patterns in shoulder impingement patients

Introduction: Shoulder impingement is one of the most common presentations of shoulder joint problems 1. It appears to be caused by a reduction in the sub-acromial space as the humerus abducts between 60o -120o – the 'painful arc'. Structures between the humeral head and the acromion are thus pinched causing pain and further pathology 2. Shoulder muscle activity can influence this joint space but it is unclear whether this is a cause or effect in impingement patients. This study aimed to observe muscle activation patterns in normal and impingement shoulder patients and determine if there were any significant differences. Method: 19 adult subjects were asked to perform shoulder abduction in their symptomatic arm and non-symptomatic. 10 of these subjects (age 47.9 ± 11.2) were screened for shoulder impingement, and 9 subjects (age 38.9 ± 14.3) had no history of shoulder pathology. Surface EMG was used to collect data for 6 shoulder muscles (Upper, middle and lower trapezius, serratus anterior, infraspinatus, middle deltoids) which was then filtered and fully rectified. Subjects performed 3 smooth unilateral abduction movements at a cadence of 16 beats of a metronome set at 60bpm, and the mean of their results was recorded. T-tests were used to indicate any statistical significance in the data sets. Significance was set at P<0.05. Results: There was a significant difference in muscle activation with serratus anterior in particular showing a very low level of activation throughout the range when compared to normal shoulder activation patterns (<30%). Middle deltoid recruitment was significantly reduced between 60-90o in the impingement group (30:58%).Trends were noted in other muscles with upper trapezius and infraspinatus activating more rapidly and erratically (63:25%; 60:27% respectively), and lower trapezius with less recruitment (13:30%) in the patient group, although these did not quite reach significance. Conclusion: There appears to be some interesting alterations in muscle recruitment patterns in impingement shoulder patients when compared against their own unaffected shoulders and the control group. In particular changes in scapula control (serratus anterior and trapezius) and lateral rotation (infraspinatus), which have direct influence on the sub-acromial space, should be noted. It is still not clear whether these alterations are causative or reactionary, but this finding gives a clear indication to the importance of addressing muscle reeducation as part of a rehabilitation programme in shoulder impingement patients

Adipose derived stromal vascular fraction: therapeutic potential of renal artery administration in renal ischaemia reperfusion injury

Shortages of kidneys for transplantation is a universal concern. Countries like the United Kingdom have had success improving the number of kidneys available notably through expanding their living donation program. However, trends indicate the discrepancy between supply and demand will never fully be met with current practise. Bioengineering of donor specific organs may provide the ultimate answer, but despite rapidly growing progress it will be many more years until complex organs, such as a kidney, are available for transplantation. Utilising kidneys that traditionally would not be considered suitable for transplantation will drastically increase the donor pool of kidneys. To implant these ‘marginal’ kidneys we have to minimise the ischaemia reperfusion injury (IRI) they sustain during the transplantation process. Cellular therapies offer the greatest potential in ameliorating transplant related IRI and allowing these marginal kidneys to recover with acceptable long-term function. The field of cellular therapies, in particular stem cell therapy, has expanded rapidly in the last ten years. Adipose tissue offers one of the most attractive sources of stem cells due to its relatively easy accessibility and high abundance of stem cells. The adipose derived stromal vascular fraction (ADSVF), which contains the adipose derived stem cells, can quickly be extracted from the adipose tissue with minimal technical expertise. Multiple animal studies of renal IRI have demonstrated significantly improved kidney function after treatment with ADSVF. However, administration of freshly isolated, uncultured ADSVF administered via the renal at the time of transplantation has never been attempted in human kidneys. Before considering clinical translation, we need to better understand the use of ADSVF in such settings. In chapter one, experiments characterise the ADSVF obtained from inguinal and peri-renal adipose tissue of both rats and humans. Chapter two describes the development of a novel animal model which closely mimics the transplant recipient in order to accurately investigate the ADSVF. Chapter three demonstrates the biodistribution of the ADSVF administered via the renal artery and chapter four highlights some of the potential mechanisms of action of the ADSVF. In summary, ADSVF from peri-renal and inguinal adipose tissue consist of a similar heterogenous cell population, although they differ in the proportions of each subset. When administered via the renal artery, ADSVF likely ameliorate IRI via multiple mechanisms, by reducing the immediate injury, modulating the inflammatory response and reducing the progression to fibrosis. Administration via the renal artery is an effective means of reducing non-target biodistribution and deliver the majority of the ADSVF to the cortex of the kidney. The animal model developed as part of this research better mimics the transplant patient, compared to existing models, without increasing the risks to the animal. The findings of this research combined with recently published data using mesenchymal stem cells in human kidney IRI, provides enough support to consider renal artery administration of uncultured ADSVF. Initially this translational research could be performed on declined kidney grafts

Development of a synthetic small calibre vascular bypass graft

Polyurethanes are an attractive class of material for bioprosthesis development due to the ability to manipulate their elasticity and strength. However, their use as long term biological implants is hampered by biodegradation. A novel polyurethane has been developed which incorporates nano-engineered polyhedral oligomeric silsesquioxane within poly(carbonate-urea) urethane to improve the biostability of the latter. Previous investigators have found this material to be cytocompatible and to have low thrombogenicity. The medium and long term clinical results of currently available prosthetic small calibre vascular bypass grafts are poor, due to neo-intimal hyperplasia associated with their non-compliant properties. The investigation reported here commences with the benchtop manufacture of compliant small calibre grafts using an original extrusion- phase inversion technique. The reproducibility of the technique as well as the effect on the pore structure of different coagulation conditions is demonstrated. Fundamental mechanical characterisation of the grafts produced is then presented, by way of tensillometry to demonstrate the viscous and elastic properties of the material. These are made more relevant to the clinical setting with functional mechanical characterisation of the grafts, showing graft compliance in a biomimetic flow circuit along with viscoelastic hysteresis, along with burst pressure testing. An examination of burst pressure testing methodology is also shown, in the light of the various non-standardised strategies reported in the graft-testing literature. Mechanical characterisation shows the short-term safety for use, but durability studies in the biological haemodynamic environment serve to assess longer term fatigability as well as confirming biostability. This has been reported using a stringent ovine carotid interposition model which remained patent over the full investigation period representing at least 45 million pulsatile cycles. Physico-chemical analysis; integrity of the structure, microstructure and ultrastructure; preservation of mechanical properties and immunohistological analysis were used to examine the grafts after implantation to show their healing properties and biostability