Chronic painful tendinopathy is a common cause for elite- and recreational athletes to stop or decrease the level of their sports activity. Recent research on innervation patterns, histopathology and possible pain mechanisms in tendons has led to an increased knowledge about the chronic painful tendon. Ultrasound (US) and colourDoppler (CD) examination showing localized high blood flow, inside and outside regions with structural tendon abnormalities, has been shown to be of importance for tendon pain. Immuno-histochemical analyses of biopsies have shown sensory and sympathetic nerves in close relation to the high blood flow outside the tendon. These findings have led to new ideas about development of new treatment methods for chronic painful tendinopathy. In study I, we evaluated the already in use, US-guided sclerosing polidocanol injection treatment of midportion Achilles tendinopathy, using two different concentrations of the substance. This study aimed to find out if there was a faster return to pain-free activity by using the concentration 10 mg/ml compared to the formerly used 5 mg/ml. There were no significant differences in the clinical results between the groups. In study II - Technical note, we aimed to develop a new one-stage surgical treatment method for patellar tendinopathy. This method was based on research concerning the innervation patterns and US and CD findings in patellar tendinopathy/ “jumper’s knee”. Technically we added ultrasound guidance to knee arthroscopy to identify and visualize the region of interest during a surgical shaving procedure. In study III, we tested the newly invented US and CD-guided arthroscopic shaving technique in a pilot study. The short-term clinical results were promising and the majority of the patients returned to pain-free activity after a short rehabilitation period. In study IV, we compared the US and CD-guided artrhroscopic shaving method with the already in use sclerosing polidocanol injection treatment in a randomized study. At short-term follow-up, the patients treated with US and CD-guided arthroscopic shaving had significantly less pain during rest and activity, were significantly more satisfied with the treatment, and had a faster return to sports, compared to the patients in the sclerosing injection group. There were no complications. In study V, at longer-term followup (endpoint 46 months) there was a significant decrease in pain during activity in both groups. There were no remaining significant differences in the pain levels during activity between the groups. The tendon structure had improved significantly in both groups. There was a significant decrease in the antero-posterior thickness of the proximal patellar tendon in patients treated with US and CD-guided arthroscopic shaving, but not in the sclerosing injection group. The CD flow had diminished significantly in both groups, and there was a correlation between low CD flow and high patient satisfaction in both groups, The CD flow decreased faster in the surgical group than in the injection group. In conclusion, this newly invented US and CD-guided arthroscopic shaving treatment, focusing on treatment outside the tendon, has shown good clinical results with pain relief and a fast return to sports activity, in patients with patellar tendinopathy.

Objective: The purpose of the study is to explore and illustrate how ultrasound midwives and medical specialist in obstetrics and gynecology believe the information given to parents about the genetic soft markers should be handled. Design: A quantitative questionnaire study with cross-sectional design. Participants: 44 ultrasound midwives and 37 medical specialists in obstetrics and gynecology. Findings: Most of the participants would like to inform before the ultrasound starts that they will be looking for genetic softmarkers during the ultrasound. Likewise the majority wanted to inform the parents about possible increases in the risk for chromosomal abnormalities based on findings on the routine ultrasound. There was a difference in frequency between those who responded that they would like to inform before the ultrasound that they will be looking for genetic softmarkers and those who responded that they believe the future parents wants information before the examination. Key conclusions: It could help health care professionals in their role as information providers if there were common recommendations for the information to be given to future parents about genetic softmarkers in connection with the routine ultrasound. / Syfte: Syftet med studien är att undersöka och belysa hur ultraljudbarnmorskor och specialistläkare inom obstetrik och gynekologi anser att informationen som ges till blivande föräldrar kring genetiska ultraljudsmarkörer bör hanteras. Design: En kvantitativ enkätstudie med tvärsnittsdesign. Deltagare: 44 ultraljudsbarnmorskor och 37 specialistläkare inom obstetrik och gynekologi. Resultat: Merparten av deltagarna vill informera innan ultraljudundersökningen börjar om att de kommer att titta efter genetiska ultraljudmarkörer under rutinultraljudet. Likaså ville majoriteten informera de blivande föräldrarna om eventuella riskökningar för kromosomavvikelser utifrån upptäckter på rutinultraljudet. Det fanns en skillnad i frekvens mellan de som svarat att de ville informera innan ultraljudsundersökningen om att de kommer att titta efter genetiska ultraljudsmarkörer och de som svarat att de tror att de blivande föräldrarna vill ha denna information innan undersökningen. Slutsats: Det skulle kunna hjälpa hälso-och sjukvårdspersonal i sin uppgift som informationsgivare om det fanns genomsamma rekommendationer för vilken information som skall ges till blivande föräldrar kring genetiska ultraljudsmarkörer i samband med rutinultraljudet. På det sättet skulle vi erbjuda en mer jämställd information och vård till hela befolkningen oberoende av var de bor.

Outlining of the prostate boundary in ultrasound images is a very useful procedure performed and subsequently used by clinicians. The contribution of the resulting segmentation is twofold. First of all, the segmentation of the prostate glands can be used to analyze the size, geometry, and volume of the gland. Such analysis is useful as it is known that the former quantities used in conjunction with a PSA blood test can be used as an indicator of malignancy in the gland itself. The second purpose of accurate segmentation is for treatment planning purposes. In brachetherapy, commonly used to treat localized prostate cancer, the accurate location of the prostate must be found so that the radioactive seeds can be placed precisely in the malignant regions. Unfortunately, the current method of segmentation of ultrasound images is performed manually by expert radiologists. Due to the abundance of ultrasound data, the process of manual segmentation can be extremely time consuming and inefficient. A much more desirable way to perform the segmentation process is through automatic procedures, which should be able to accurately and efficiently extract the boundary of the prostate gland with minimal user intervention. This is the ultimate goal of the proposed approach. The proposed segmentation algorithm uses a probability distribution tracking framework to accurately and efficiently perform the task at hand. The basis for this methodology is to extract image and shape features from available manually segmented ultrasound images for which the actual prostate region is known. Then, the segmentation algorithm seeks a region in new ultrasound images whose features closely mirror the learned features of known prostate regions. Promising results were achieved using this method in a series of in silico and in vivo experiments.

Vascular diseases are among the leading causes of death in Canada and around the globe. A major underlying cause of most such medical conditions is atherosclerosis, a gradual accumulation of plaque on the walls of blood vessels. Particularly vulnerable to atherosclerosis is the carotid artery, which carries blood to the brain. Dangerous narrowing of the carotid artery can lead to embolism, a dislodgement of plaque fragments which travel to the brain and are the cause of most strokes. If this pathology can be detected early, such a deadly scenario can be potentially prevented through treatment or surgery. This not only improves the patient's prognosis, but also dramatically lowers the overall cost of their treatment. Medical imaging is an indispensable tool for early detection of atherosclerosis, in particular since the exact location and shape of the plaque need to be known for accurate diagnosis. This can be achieved by locating the plaque inside the artery and measuring its volume or texture, a process which is greatly aided by image segmentation. In particular, the use of ultrasound imaging is desirable because it is a cost-effective and safe modality. However, ultrasonic images depict sound-reflecting properties of tissue, and thus suffer from a number of unique artifacts not present in other medical images, such as acoustic shadowing, speckle noise and discontinuous tissue boundaries. A robust ultrasound image segmentation technique must take these properties into account. Prior to segmentation, an important pre-processing step is the extraction of a series of features from the image via application of various transforms and non-linear filters. A number of such features are explored and evaluated, many of them resulting in piecewise smooth images. It is also proposed to decompose the ultrasound image into several statistically distinct components. These components can be then used as features directly, or other features can be obtained from them instead of the original image. The decomposition scheme is derived using Maximum-a-Posteriori estimation framework and is efficiently computable. Furthermore, this work presents and evaluates an algorithm for segmenting the carotid artery in 3D ultrasound images from other tissues. The algorithm incorporates information from different sources using an energy minimization framework. Using the ultrasound image itself, statistical differences between the region of interest and its background are exploited, and maximal overlap with strong image edges encouraged. In order to aid the convergence to anatomically accurate shapes, as well as to deal with the above-mentioned artifacts, prior knowledge is incorporated into the algorithm by using weak geometric priors. The performance of the algorithm is tested on a number of available 3D images, and encouraging results are obtained and discussed.

Polycystic ovary syndrome (PCOS) is an endocrine abnormality with multiple diagnostic criteria due to its heterogenic manifestations. One of the diagnostic criterion includes analysis of ultrasound images of ovaries for the detection of number, size, and distribution of follicles within the ovary. This involves manual tracing of follicles on the ultrasound images to determine the presence of a polycystic ovary (PCO). A novel method that automates PCO morphology detection is described. Our algorithm involves automatic segmentation of follicles from ultrasound images, quantifying the attributes of the segmented follicles using stereology, storing follicle attributes as feature vectors, and finally classification of the feature vector into two categories. The classification categories are PCO morphology present and PCO morphology absent. An automatic PCO diagnostic tool would save considerable time spent on manual tracing of follicles and measuring the length and width of every follicle. Our procedure was able to achieve classification accuracy of 92.86% using a linear discriminant classifier. Our classifier will improve the rapidity and accuracy of PCOS diagnosis, and reduce the chance of the severe health implications that can arise from delayed diagnosis.

Coronary heart diseases are a significant cause of death among both men and women in the industrialized world; thus finding ways to detect factors which cause coronary heart diseases is worthy challenge for researchers. Ultrasound elastography system (50MHz) for measuring mechanical properties of arteries was developed as part of this thesis. Ability to discriminate between various tissue types was demonstrated using fresh and modified porcine coronary arteries, which closely models the plaque in human atherosclerosis. Elastographic measurements agreed well with uniaxial mechanical testing over a range of compression moduli.

An understanding of the generation of higher harmonics in Lamb waves is of critical importance for applications such as remaining life prediction of plate-like structural components. The objective of this work is to use nonlinear Lamb waves to experimentally investigate inherent material nonlinearities in aluminum plates. These nonlinearities, e.g. lattice anharmonicities, precipitates or vacancies, cause higher harmonics to form in propagating Lamb waves. The amplitudes of the higher harmonics increase with increasing propagation distance due to the accumulation of nonlinearity while the Lamb wave travels along its path. Special focus is laid on the second harmonic, and a relative nonlinearity parameter is defined as a function of the fundamental and second harmonic amplitude. The experimental setup uses an ultrasonic transducer and a wedge for the Lamb wave generation and laser interferometry for detection. The experimentally measured Lamb wave signals are processed with a short-time Fourier transformation (STFT) and a chirplet transformation-based algorithm, which yield the amplitudes of the frequency spectrum as functions of time, allowing the observation of the nonlinear behavior of the material. The increase of the relative nonlinearity parameter with propagation distance as an indicator of cumulative second harmonic generation is shown in the results for two different aluminum alloys. The difference in inherent nonlinearity between both alloys as determined from longitudinal wave measurements can be observed for the Lamb wave measurements, too.

Elastography is a non-invasive imaging modality that uses ultrasound to estimate the elasticity of soft tissues. The resulting images are called 'elastograms'. Elastography techniques are promising as cost-effective tools in the early detection of pathological changes in soft tissues. The quality of elastographic images depends on the accuracy of the local displacement estimates. Cross-correlation based displacement estimators are precise and sensitive. However cross-correlation based techniques are computationally intense and may limit the use of elastography as a real-time diagnostic tool. This study investigates the use of parallel general purpose graphics processing unit (GPGPU) engines for speeding up generation of elastograms at real-time frame rates while preserving elastographic image quality. To achieve this goal, a cross-correlation based time-delay estimation algorithm was developed in C programming language and was profiled to locate performance blocks. The hotspots were addressed by employing software pipelining, read-ahead and eliminating redundant computations. The algorithm was then analyzed for parallelization on GPGPU and the stages that would map well to the GPGPU hardware were identified. By employing optimization principles for efficient memory access and efficient execution, a net improvement of 67x with respect to the original optimized C version of the estimator was achieved. For typical diagnostic depths of 3-4cm and elastographic processing parameters, this implementation can yield elastographic frame rates in the order of 50fps. It was also observed that all of the stages in elastography cannot be offloaded to the GPGPU for computation because some stages have sub-optimal memory access patterns. Additionally, data transfer from graphics card memory to system memory can be efficiently overlapped with concurrent CPU execution. Therefore a hybrid model of computation where computational load is optimally distributed between CPU and GPGPU was identified as an optimal approach to adequately tackle the speed-quality problem in real-time imaging. The results of this research suggest that use of GPGPU as a co-processor to CPU may allow generation of elastograms at real time frame rates without significant compromise in image quality, a scenario that could be very favorable in real-time clinical elastography.

In the study of the mechanical behavior of biological tissues, many complex tissues are often modeled as poroelastic systems due to their high fluid content and mobility. Fluid content and fluid transport mechanisms in tissues are known to be highly correlated with several pathologies. Thus, imaging techniques capable of providing accurate information about these mechanisms can potentially be of great diagnostic value. Ultrasound elastography is an imaging modality that is currently used as a complement to sonographic methods to detect a variety of tissue pathologies. Poroelastography is a new elastographic technique that has been recently proposed to image the mechanical behavior of tissues that can be modeled as poroelastic media. The few poroelastographic studies retrievable focus primarily on homogeneous poroelastic media. In this study, a statistical analysis of the performance of poroelastographic techniques in a non-homogeneous poroelastic simulation model under different loading conditions was carried out. The two loading conditions simulated were stress relaxation (application of constant strain) and creep compression (application of constant stress), both of which have been commonly used in the field of poroelastography. Simulations were performed using a FE poroelastic simulation software combined with ultrasound simulation software techniques and poroelastography processing algorithms developed in our laboratory. The non-homogeneous poroelastic medium was modeled as a cube (background) containing a cylindrical inclusion (target). Different permeability, Young’s modulus and Poisson’s ratio contrasts between the underlying matrix of the background and the target were considered. Both stress relaxation and creep compression loading conditions were simulated. The performance of poroelastography techniques was quantified in terms of accuracy, elastographic contrast–to–noise ratio and contrast transfer efficiency. The results of this study show that, in general, image quality of both axial strain and effective Poisson’s ratio poroelastograms is a complex function of time, which depends on the contrast between the poroelastic material properties of the background and the poroelastic material properties of the target and the boundary conditions. The results of this study could have important implications in defining the clinical range of applications of poroelastographic techniques and in the methodologies currently deployed.

ABSTRACT The effects of ultrasonic irradiation at different frequencies, i.e. 0.25, 0.5, 1, and 5 MHz, on the biological reaction of the single cell creature have been investigated. When multi-cell creature is exposed to ultrasound, this reaction will lead the biological effect becomes complex. Therefore, in this dissertation, a single cell creature is chosen to study the biological effects induced by ultrasound exposure. The paramecium, which possesses many features typical of higher-order animal cells, was considered as an appropriate choice for this study. The ability shown by ultrasound in promoting and/or accelerating many reactions has been shown to be a useful field. The resonant frequency of paramecium by using the ultrasound irradiation is an important parameter in this research. All other parameters being kept constant, it has been ascertained that an appropriate frequency value of ultrasound can be selected, capable of driving a biological reaction to its suitable yield. The oscillation of the cells in response to the ultrasound radiation is simulated using Rayleigh-Plesset¡¦s bubble activation theory. The resonant frequency of the unicellular creature is then calculated. In the experiment, the resonant (0.5 and 1 MHz) and non-resonant (0.25 and 5 MHz) frequencies were employed. The theoretical resonant frequency of the paramecium vacuole is among 0.5013~1.2703 MHz. In this thesis, the experiment included two different series. The exposure intensity is the major subject of the first experimental series to study the bioeffect of ultrasound. The waveform was set to the tone pulse mode, pulsing 1:1. The exposure duration was continued and maintained 5 minutes. For a given frequency, exposures of the paramecium were made over a range of intensities spanning 0 to 1.7 mW/cm2. The second experimental series was focused on the exposure duration of the ultrasound. The transducers were operating in a pulsed mode with two duty cycles of 1:1 and 1:9. All insonated samples were exposed to ultrasound with a spatial peak temporal peak intensity (SPTP) of 0.127 mW/cm2. The total ¡§with signal¡¨ time was about 6 minutes in each trial. In addition, the control samples and the treated samples would be re-incubated up to the 96 hr. When the 1 MHz frequency of ultrasound was irradiated in the samples, there was about 24% inhibition rate and 30% enhancement rate in the first experimental series. The 0.5 MHz frequency of ultrasound, which approaches to the resonant frequency range, also appeared the inhibitive and beneficial effect. In the second experimental series, the relative growth number was about 32.4% higher than that of unexposed sample. The inhibition or enhancement growth conditions did not appear apparently during irradiation the non-resonant frequency of ultrasound. Moreover, experimental evidence suggests that the sustaining growth effect can be expected, when the irradiation time is divided into parts.