Neste trabalho é analisada a medição de viscosidade de líquidos por ultrasom pelo método da reflexão de ondas de cisalhamento. O método baseiase na medição da magnitude e fase do coeficiente de reflexão quando as ondas de cisalhamento incidem na interface entre um sólido e o líquido testado. Foram analisados os conceitos teóricos do método da medição de viscosidade e desenvolvida a metodologia experimental a fim de evitar a influência indesejada de fatores externos, como a temperatura e a instabilidade da eletrônica, sobre a medição. Foram obtidos resultados com dois óleos alimentícios (azeite de oliva e óleo de milho) e quatro óleos automotivos do tipo SAE (40, 90, 140 e 250). Foi mostrado que para uma freqüência de operação baixa o suficiente para garantir comportamento Newtoniano do líquido, os valores de viscosidade têm excelente concordância numérica com os valores obtidos usando o viscosímetro rotacional, no caso dos óleos menos viscosos. Já no caso dos óleos mais viscosos, foram obtidos valores de viscosidade menores que os obtidos com viscosímetro rotacional, e o aumento no módulo elástico sugere um comportamento mais viscoelástico. Foi mostrado que o método de cálculo simplificado usado por alguns autores, que permite calcular a viscosidade a partir somente da magnitude do coeficiente de reflexão, não fornece os valores esperados de viscosidade. / This work deals with the ultrasonic measurement of liquids viscosity by means of the shear reflectance method. The method is based on the measurement of the magnitude and phase of the complex reflection coefficient of shear waves at a solidliquid sample interface. Basic concepts of the viscosity measurement method were analyzed and the experimental methodology was developed to avoid the undesired influence of external factors, such as temperature and electronic instability. Experimental results were obtained with two kinds of eatable oils (olive and corn oils) and four different automotive oils (SAE 40, 90, 140 e 250). For an operating frequency low enough to obtain Newtonian liquid behavior, as for less viscous liquids, it was shown that the viscosity results have good agreement with rotational viscometer measurements. In the case of more viscous liquids, the measured viscosity values were smaller than those obtained by the rotational viscometer, and the elastic modulus is increased, suggesting viscoelastic behavior. It is shown that a simplified model used by other authors, which obtains the viscosity without measuring the phase of the complex reflection coefficient, results in greater errors associated with the values obtained by the rotational viscometer.

This study aims to compare the physical properties of denture base resin after staining by beverages, treatment by four cleaning methods, and selecting the optimal cleaning method. Two hundred and ninety square Lucitone dental acrylic specimens were fabricated. Three relevant experiences are performed. Part I will compare cleaning methods effects on physical properties of denture resin. The purpose of this part is to test the effects of different cleaning methods on the physical properties of the denture resin on ideal condition (without stain). Part II will compare the staining effects on denture resin. The purpose of this part is to find the impact of different dyes on the physical properties of the denture resin without cleaning. Part III will compare staining and cleaning effects on denture resin. The purpose of this part is to select the best cleaning methods with less defect and more efficient for denture cleaning. Significance differences are found between different cleaning methods and stains. For all stain, denture cleanser combined brushing is more efficient to remove the stain than other cleaning methods. However, this method causes significate damage to denture base resin. Meanwhile, ultrasonic combine denture cleanser showed lower changes in surface roughness, weight and thickness, and higher surface hardness. In red wine staining, cleaning denture with ultrasound only showed lower differences and higher surface hardness. Within the scope of this study, the optimal selections of denture base cleaning methods for different stains are suggested. For coffee and tea stains, ultrasonication after cleanser application causes fewer effects on physical properties and better efficiency for stain removal than other cleaning methods. For red wine stains, cleaning dentures with ultrasound only cause a fewer impact on material properties and more efficient stain removal. In the clinic, home-care and cleaning protocol should explain to denture patient at the delivery appointment. Instead of giving the universal instruction, customization cleaning protocols are preferred to individual patients. Social hobbies especially the diet of the patient should be analyzed individually. According to the present study, a customized combined cleaning protocol can recommend to the individual patient and the improvement of denture longevity can be predicted. / 2020-08-06T00:00:00Z

STUDY DESIGN: Randomized crossover experiment. OBJECTIVE: To determine whether the Rich-Mar AutoSound™ would be as effective as traditional ultrasound at increasing the temperature of the triceps surae muscle during a 10-min, 1 MHz, 1.0 W/cm2 ultrasound treatment. BACKGROUND: The AutoSound™ is a hands-free ultrasound device that is strapped on the body and left for the duration of the ultrasound treatment. It requires no clinician during the actual ultrasound treatment, thus freeing the clinician to perform other tasks and reducing clinician error during treatments. METHODS: 16 healthy subjects (6 males, 10 females, age = 22 ± 1.6 yrs, height = 173.2 ± 8.4 cm, weight = 72.5 ± 11.3 kg, triceps surae subcutaneous fat thickness = 0.85 ± 0.37 cm) received a 10-min, 1 MHz, 1.0 W/cm2 ultrasound treatment over their left triceps surae muscle with both the AutoSound™ and traditional ultrasound (via the TheraHammer™) with 24 hours between treatments. Temperatures were measured every 30 seconds during the ultrasound treatments by way of a thermistor, approximately 2.25 cm deep in the triceps surae. RESULTS: The AutoSound™ was not effective at increasing the temperature of the triceps surae muscle, as temperature decreased 0.16°C during treatment (p = 0.334). On average, the AutoSound™ caused intramuscular temperature to decrease at a rate of 0.016 ± 0.001°C per min. Traditional ultrasound performed using the TheraHammer™ had a total temperature increase of 0.41°C. Rate of temperature increase during traditional ultrasound was 0.025 ± 0.003°C per min (p < 0.0001). CONCLUSION: The AutoSound™ is not as effective at increasing muscle temperature as traditional ultrasound during a 10-min, 1 MHz, 1.0 W/cm2 treatment. However, neither the AutoSound™ nor traditional ultrasound was very effective at increasing the temperature of the triceps surae muscle during the treatment time.

The aim of this study was to clarify the relationship between the dosage parameters and temperature increase at the target tissues (up to 5 cm below the skin surface), and to explore the possibility of proposing a preliminary model to guide clinicians and researchers in determining treatment dosages based on expected increase in temperatures at the target tissue. Prior to the conduct of the main study several protocol-related issues were investigated. These included the reliability of the measurement procedures, the optimum speed of movement of the transducer, the optimum size of the treatment area, and the maximum output intensity that could be considered safe for treatment applications and investigations. An in-vitro post-mortem pig model was chosen for the experimental design using only adult-sized pigs, weighing between 60 to 80 kilograms. A total of 76 specimens were obtained from the shoulder and thigh sections of 19 pigs. The therapeutic ultrasound machine used throughout the study was the Omnisound 3000TM (Physio Technology Inc., Topeka, Kansas, USA) Output from the Omnisound 3000TM was checked and calibrated as necessary prior to each experiment using a power meter (Model UPM-DT-10, Ohmnic Instruments Co., St. Michaels, Maryland 21663, USA). Calibration was only performed when the checks demonstrated an error in the output intensity of the machine exceeded ±10%. The Minolta spot thermometer (HT-11, Minolta Co. Ltd., Japan) and the Avio thermal video system (TVS) 2000TM (Nippon Avionics Co. Ltd., Japan) were used to measure the change in tissue temperatures (dependent variable) at the skin surface and subcutaneously (at l, 2, 3, 4 and 5 cm below skin surface) respectively. The prepared specimen was mounted on a fixed table, with the clean cross-section facing the infrared thermographic camera. / The camera to specimen distance was standardised at 50 cm for all experiments. Markers corresponding to 1, 2, 3, 4, and 5 cm on the specimen were plotted on the display unit, and saved to a 3.5 inch floppy disk. Measurements were recorded at baseline (prior to commencement of the experiment) and subsequently at 1-minute intervals during 10 minutes of exposure to the ultrasound, and for a further 10 minutes post-exposure, until the end of the experiment at 20 minutes. In general, there were five main parameters for all the studies: the movement speed of the transducer, the size of the treatment, and the frequency, intensity and duration of exposure and post-exposure to ultrasound. These five parameters represented the independent variables for all the studies. The dependent variable throughout was change in tissue temperature (measured in °C) at the skin surface, and at 1, 2, 3, 4 and 5 cm below the skin surface. Data were analysed using the SPSS for Windows software, Version 10.0 (SPSS Inc., 444N Michigan Avenue, Chicago, Illinois 60611, USA). Analyses of the data, using a repeated measures analysis of variance procedure, were performed on change in temperature, rather than actual temperature measured at selected time points. Only data from the 5th, 10th, 15th, and 20th minutes were analysed. This corresponded to the middle and end of the ultrasound exposure phase (5th and 10th minute) and post-exposure phase (15th and 20th minute), as these were considered to be representative of both these phases of data collection. / Data for all 20-minute sampling is provided in the table of means for each experiment. The level of statistical significance was set at 0.05. Results of the reliability study showed that both the infrared spot thermometer and the video thermography unit were reliable within acceptable limits (as defined in this study). The latter, however, was more reliable than the former. In addition, the reliability was better for the post-exposure phase compared with the exposure phase, and for deeper tissues compared with the superficial and surface tissues. An unplanned analysis of the twenty minutes of data (at one minute intervals) suggested the possibility of reducing the duration factor from 20 to 4 (5th, 10th, 15th and 20th minute). In this manner, the data analyses for subsequent studies could be simplified considerably without affecting the overall results. Results of the other protocol-related studies showed that: a. There was no difference in change in temperatures between the slow (60 beats/min or 7cm/s), moderate (120 beats/min or 14cm/s) and fast (180 beats/min or 21cm/s) movement speeds of the transducer. However, for practical reasons, the moderate speed was recommended for subsequent studies; b. There was a significant difference in change in temperatures between the small (2X ERA), medium (3X ERA) and large (4X ERA) treatment sizes. The small treatment size provided the most effective and deeper heating, and was the recommended treatment size for subsequent studies; c. For both 1 and 3 MHz, tissue damage did not occur for intensities up to 1.5 Watts/cm[superscript]2. However, irreversible thermal injury to the tissues occurred at 2.0 Watts/cm[superscript]2 (1 MHz). / Therefore, the recommended maximum intensity at which investigations could be carried out without any risks of thermal injury to the tissues was 1.5 Watt s/cm[superscript]2 for both 1 and 3 MHz. The results from the main study demonstrated that the increase in temperature due to absorption of the ultrasonic energy at any of the investigated target sites (up to 5 cm below surface) was related to the ultrasound frequency, intensity and duration of exposure. For the frequency factor, the evidence seems to suggest that compared with the 3 MHz ultrasound, the 1 MHz frequency may be more appropriate for clinical applications as it does not overheat surface tissues, and at the same time, is able to increase the temperatures of target tissues up to a depth of 5 cm. For the intensity factor, the results suggest that the therapeutic range of intensities which can be considered neither too low (as to be ineffective) nor too high (as to be damaging) are 0.5 to 1.3 Watts/cm 2 and 0.3 to 0.5 Watts/cm[superscript]2 for 1 and 3 MHz respectively The narrow therapeutic range for 3 MHz could render it questionable for clinical applications. In contrast, the larger therapeutic range available for the 1 MHz frequency suggests that it is more suitable for clinical applications and research. For the duration factor, the results demonstrated that the temperatures at all tissue sites increased as the duration of exposure increased. / However, for the post-exposure phase, while the superficial tissues decreased with time, the deeper tissues continued to increase in their temperatures, albeit gradually. In summary, the results demonstrated that a higher frequency, a higher intensity, a greater exposure time and a more superficial site all contribute to a greater change in mean temperature. From these results, a preliminary model to guide clinicians and researchers in determining treatment dosages, based on expected increase in tissue temperatures at the target site, was proposed. While the preliminary model provided is only a first step effort, it is hoped that it can be refined further through use by physical therapists and other users of therapeutic ultrasound.

Doctor of Philosophy (Medicine) / This work investigates a number of issues. Firstly it examines ultrasonic fetal biometry, the parameters and techniques for accurate measuring and reviews the procedure adopted for graph formation and application of regression analysis for a mathematical model to describe the relationship between fetal size and weeks of gestation. Next it establishes new Australian fetal measurement charts for the crown rump length, head circumference and abdominal circumference, based on an Australian population, to replace the charts currently in use that are over 20 years old and relate to middle class white American and British women. The new graphs, along with previous work completed by the author in 1999 on the BPD, OFD femur and humerus length, were subsequently accepted by the Australasian Society for Ultrasound in Medicine (ASUM) in 2001 as the new Australian standard for ultrasonic fetal measurements. The accuracy of first trimester ultrasound dating is also investigated, displaying the variations seen in the crown-rump length due to fetal flexion and the implications of inaccurate measuring. The third study examines inter- and intra-sonographer ultrasonic fetal measurement reproducibility in the final 6 weeks of pregnancy. The study highlights the importance of sonographer competence, standardised measuring protocols, image planes and reference charts, particularly for patients undergoing ultrasound examinations for fetal growth assessment at different practices. The fourth study looks at the incidence of fetal macrosomia and birth complications in Chinese women and Caucasian women in two time periods, 1992 and 1999/2000. The results showed a rise in macrosomic babies born to Chinese immigrants from 4% of total Chinese births in 1992 to 9.8% in 1999/2000. There was also a rise in the rate of macrosomia among Caucasian women with respective rates of 11 and 14% for the same periods. The incidence of post partum haemorrhage increased significantly over this time in both Chinese immigrant and Caucasian women. Interventions declined in all Caucasian birth-weight ranges whilst interventions for Chinese births remained stable except between 3500grams and 4000grams, where interventions rose from 35.7% to 60.5%. Fetal macrosomia is a complication of pregnancy that is increasing in incidence. One of the causes of fetal overgrowth is uncontrolled gestational diabetes mellitus and so if women thus diagnosed are closely monitored, the risks of a macrosomic baby and associated birth complications may be reduced. The final study examines the effect of gestational diabetes mellitus (GDM) on fetal growth. GDM is a complication of mid to late pregnancy caused by glucose intolerance. In the Australian population up to 8% of all pregnancies can be affected. In the Australian Chinese community the GDM rate is as high as 15% compared with 4% in Caucasian women. The risks to the fetus as a result of GDM include increased perinatal mortality, large for gestational dates, macrosomia and prematurity. The aim of this study was to determine whether the fetuses of women diagnosed with GDM were significantly larger for dates for any of the commonly ultrasonically measured fetal parameters, than in the general pregnant population. The results show that if the glycaemic levels are properly controlled, fetal size should not be compromised. The abdominal circumference measurement appears to be the important marker for fetal macrosomia, particularly in the Chinese population. The study also assessed fetal weight gain from 36 weeks gestation to term in Caucasian women with GDM and Chinese pregnancies both with and without GDM. No statistically significant difference was seen in daily weight gain between the groups investigated.

<p>Ultralyd er i dag et standardverktøy innen hjertediagnostikk. Analyse av ventrikkelfunksjon gjøres subjektivt ved å se på gråskala ultralydopptak av hjertet. Dette gjør dokumentasjon og opplæring vanskelig. Det er derfor ønskelig med kvantitative mål på ventrikkelfunksjon. Kvantitative metoder kan benytte høy tidsoppløsning og dermed også registrere flere detaljer.</p><p>To teknikker for kvantitativ ventrikkelanalyse er vevs-Doppler og speckle tracking (mønsterfølging). Ved bruk av disse teknikkene er det viktig å sikre kvaliteten av resultatene samtidig som analyseprosessen kan gjennomføres så effektivt som mulig. I denne avhandlingen presenteres flere metoder for å sikre kvalitet og øke effektivitet ved kvantitativ ventrikkelanalyse som alle er relatert til bruk av høy tidsoppløsning.</p><p>For å kunne gjøre effektiv ventrikkelanalyse behøves analyseverktøy. Et slikt verktøy som fungerer med både vevs-Doppler og speckle tracking presenteres i denne avhandlingen. Dette verktøyet har gjort flere store kliniske studier mulig. Ved analyse av hendelsene som skjer innen en hjertesykel er det viktig å dele opp hjertesykelen i ulike faser. Venstre ventrikkels tømmingsfase avsluttes ved at aortaklaffen lukkes, og denne hendelsen må derfor bestemmes før kvantitative parametre i slutten av tømmingsfasen og i overgangen til fyllingsfasen kan bestemmes. I denne avhandlingen vurderes og testes ulike kandidater for bestemmelse av lukkingen. To gunstige kandidater i hastighetskurver fra basale deler av ventrikkelen ble funnet: andre nullkryssing etter tømming og høyeste positive akselerasjon etter tømming før fylling. Et eget bidrag viser at den siste av disse kan bestemmes automatisk. For å oppnå høy tidsoppløsning kreves høy datarate. En populær metode for å øke datarate er flere parallelle mottaksstråler for hver sendestråle. I vanlig gråtoneavbilding av hjertet er det imidlertid observert at dette medfører uønskede linjelignende strukturer i bildet. I denne avhandlingen vises det at årsaken til dette er at de parallelle strålene deformeres når de passerer strukturene mellom hjertet og proben. Avhandlingen inneholder også et bidrag som viser hvordan bruk av parallelle mottakstråler kan medføre at vevs-Doppler kurver blir hentet fra et annet sted i hjertet enn det intensjonen var. Samlet er avhandlingen et bidrag til fortsatt utvikling og forbedring av kvantitative ultralydmetoder innen hjertediagnostikk.</p>

<p>The purpose of this thesis was to evaluate the diagnostic potential of a new ultrasound contrast agent,Sonazoid^TM, intended for use in patients with suspicion of prostate cancer.</p><p>The sonographic appearance of normal prostatic vascularity in dogs was evaluated before and after injection of Sonazoid,using different Doppler flow detection modes.The use of Sonazoid significantly improved the visibility of the vascular pattern in normal dog prostate,both with colour and power Doppler imaging.There was a significant difference in the depiction of blood flow in the prostate between the two imaging modalities,showing the power Doppler superior to colour Doppler imaging.The contrast revealed a radial,spoke-like intraprostatic pattern,not seen prior to contrast injection.</p><p>Different ultrasound imaging modalities were tested in a small group of young healthy male volunteers to evaluate the visibility of the normal prostate blood flow with and without Sonazoid.</p><p>The ultrasound contrast agent improved the visibility of the normal human prostate vascular anatomy for both colour and power Doppler imaging.Again,the improvement was significantly better for power Doppler than for colour Doppler imaging.Using fundamental B-mode,there was no major difference in the ultrasound appearance of the prost ate vascular it y before and after i njection of Sonazoid.Cont rast dynamic st udies of blood flow wit hi n t he normal gland showed a filling from the periphery towards the centre in all subjects,demonstrating a symmetric, radial vascular pattern.</p><p>A canine prostate model was used to investigate if Sonazoid,could improve the visualisation of prostatic vessels to better delineate areas on normal and decreased blood flow.Both 2D and 3D power Doppler imaging was performed in this study.The visibility of the prostate blood flow improved significantly following injection of Sonazoid for both 2D and 3D power Doppler imaging.There was,however,no major difference in depicting the vascularity using 2D and 3D imaging.After injection of Sonazoid,a disturbance of the radial vascular pattern and a lack of blood flow symmetry between the two prostate lobes were possible to identify.The added information gained by injection of Sonazoid made it possible to identify areas of decreased blood flow not seen prior to contrast injection.</p><p>The vascular pattern of lesions,identified with B-mode imaging in patients with suspicion of prostate cancer,was studied,using Sonazoid.Contrast dynamic inflow in the lesions,compared to the adjacent tissue was investigated in the same study.Prostate cancer lesions appeared hypervasuclar prior to ultrasound contrast agent.Three of six cancer lesions changed from hypervascular to marked hypervascular following injection of Sonazoid,a finding that might be interpreted as a higher level of confidence.None of the non-cancer lesions were assessed as hypervascular after Sonazoid injection,a possible increased value of a negative finding.Four of the cancer lesions enhanced earlier compared to the surrounding prostate tissue,following ultrasound contrast injection.The results indicate that changes in vascular architecture,e.g.induction of angiogenesis by tumour cells,can be observed by ultrasonographically determining the inflow pattern of an intravenously injected ultrasound contrast agent.</p>

Thesis (M.S.M.E.)--University of Delaware, 2006. / Principal faculty advisor: Kausik Sarkar, Dept. of Mechanical Engineering. Includes bibliographical references.

The purpose of this thesis was to evaluate the diagnostic potential of a new ultrasound contrast agent,SonazoidTM, intended for use in patients with suspicion of prostate cancer. The sonographic appearance of normal prostatic vascularity in dogs was evaluated before and after injection of Sonazoid,using different Doppler flow detection modes.The use of Sonazoid significantly improved the visibility of the vascular pattern in normal dog prostate,both with colour and power Doppler imaging.There was a significant difference in the depiction of blood flow in the prostate between the two imaging modalities,showing the power Doppler superior to colour Doppler imaging.The contrast revealed a radial,spoke-like intraprostatic pattern,not seen prior to contrast injection. Different ultrasound imaging modalities were tested in a small group of young healthy male volunteers to evaluate the visibility of the normal prostate blood flow with and without Sonazoid. The ultrasound contrast agent improved the visibility of the normal human prostate vascular anatomy for both colour and power Doppler imaging.Again,the improvement was significantly better for power Doppler than for colour Doppler imaging.Using fundamental B-mode,there was no major difference in the ultrasound appearance of the prost ate vascular it y before and after i njection of Sonazoid.Cont rast dynamic st udies of blood flow wit hi n t he normal gland showed a filling from the periphery towards the centre in all subjects,demonstrating a symmetric, radial vascular pattern. A canine prostate model was used to investigate if Sonazoid,could improve the visualisation of prostatic vessels to better delineate areas on normal and decreased blood flow.Both 2D and 3D power Doppler imaging was performed in this study.The visibility of the prostate blood flow improved significantly following injection of Sonazoid for both 2D and 3D power Doppler imaging.There was,however,no major difference in depicting the vascularity using 2D and 3D imaging.After injection of Sonazoid,a disturbance of the radial vascular pattern and a lack of blood flow symmetry between the two prostate lobes were possible to identify.The added information gained by injection of Sonazoid made it possible to identify areas of decreased blood flow not seen prior to contrast injection. The vascular pattern of lesions,identified with B-mode imaging in patients with suspicion of prostate cancer,was studied,using Sonazoid.Contrast dynamic inflow in the lesions,compared to the adjacent tissue was investigated in the same study.Prostate cancer lesions appeared hypervasuclar prior to ultrasound contrast agent.Three of six cancer lesions changed from hypervascular to marked hypervascular following injection of Sonazoid,a finding that might be interpreted as a higher level of confidence.None of the non-cancer lesions were assessed as hypervascular after Sonazoid injection,a possible increased value of a negative finding.Four of the cancer lesions enhanced earlier compared to the surrounding prostate tissue,following ultrasound contrast injection.The results indicate that changes in vascular architecture,e.g.induction of angiogenesis by tumour cells,can be observed by ultrasonographically determining the inflow pattern of an intravenously injected ultrasound contrast agent.

Ultralyd er i dag et standardverktøy innen hjertediagnostikk. Analyse av ventrikkelfunksjon gjøres subjektivt ved å se på gråskala ultralydopptak av hjertet. Dette gjør dokumentasjon og opplæring vanskelig. Det er derfor ønskelig med kvantitative mål på ventrikkelfunksjon. Kvantitative metoder kan benytte høy tidsoppløsning og dermed også registrere flere detaljer. To teknikker for kvantitativ ventrikkelanalyse er vevs-Doppler og speckle tracking (mønsterfølging). Ved bruk av disse teknikkene er det viktig å sikre kvaliteten av resultatene samtidig som analyseprosessen kan gjennomføres så effektivt som mulig. I denne avhandlingen presenteres flere metoder for å sikre kvalitet og øke effektivitet ved kvantitativ ventrikkelanalyse som alle er relatert til bruk av høy tidsoppløsning. For å kunne gjøre effektiv ventrikkelanalyse behøves analyseverktøy. Et slikt verktøy som fungerer med både vevs-Doppler og speckle tracking presenteres i denne avhandlingen. Dette verktøyet har gjort flere store kliniske studier mulig. Ved analyse av hendelsene som skjer innen en hjertesykel er det viktig å dele opp hjertesykelen i ulike faser. Venstre ventrikkels tømmingsfase avsluttes ved at aortaklaffen lukkes, og denne hendelsen må derfor bestemmes før kvantitative parametre i slutten av tømmingsfasen og i overgangen til fyllingsfasen kan bestemmes. I denne avhandlingen vurderes og testes ulike kandidater for bestemmelse av lukkingen. To gunstige kandidater i hastighetskurver fra basale deler av ventrikkelen ble funnet: andre nullkryssing etter tømming og høyeste positive akselerasjon etter tømming før fylling. Et eget bidrag viser at den siste av disse kan bestemmes automatisk. For å oppnå høy tidsoppløsning kreves høy datarate. En populær metode for å øke datarate er flere parallelle mottaksstråler for hver sendestråle. I vanlig gråtoneavbilding av hjertet er det imidlertid observert at dette medfører uønskede linjelignende strukturer i bildet. I denne avhandlingen vises det at årsaken til dette er at de parallelle strålene deformeres når de passerer strukturene mellom hjertet og proben. Avhandlingen inneholder også et bidrag som viser hvordan bruk av parallelle mottakstråler kan medføre at vevs-Doppler kurver blir hentet fra et annet sted i hjertet enn det intensjonen var. Samlet er avhandlingen et bidrag til fortsatt utvikling og forbedring av kvantitative ultralydmetoder innen hjertediagnostikk.