Master thesis and projects

– Ultrasound technology

The department of circulation and medical imaging offers projects and master thesis topics for technology students of most of the different technical study programs at NTNU. There is an own page for the supplementary specialization courses.

List of topics

Topics for thesis and projects are given below. Most of the topics can be adjusted to the students qualifications and wishes.

Don't hesitate to take contact with the corresponding supervisor - we're looking forward to a discussion with you!

Blood flow imaging projects

Examining small baby using ultrasound. Photo: Geir Mogen/NTNU

Ultrasound blood flow imaging - a bit of background:

One of the strengths of ultrasound imaging is its ability to measure blood and tissue velocities with high precision and at a high frame rate. Information of blood velocities can in the diagnostic setting be used to identify abnormal blood flow related to pathology, such as the jet flow pattern resulting from a heart valve leakage. Further, information about tissue velocities can be used to quantify the function of the heart, through the identification of areas of the heart muscle with reduced contractibility.You can read more about Tissue Velocity Imaging here.

Blood flow imaging projects

Examining small baby using ultrasound. Photo: Geir Mogen/NTNU

Ultrasound blood flow imaging - a bit of background:

One of the strengths of ultrasound imaging is its ability to measure blood and tissue velocities with high precision and at a high frame rate. Information of blood velocities can in the diagnostic setting be used to identify abnormal blood flow related to pathology, such as the jet flow pattern resulting from a heart valve leakage. Further, information about tissue velocities can be used to quantify the function of the heart, through the identification of areas of the heart muscle with reduced contractibility.You can read more about Tissue Velocity Imaging here.

Traditional velocity measurements with ultrasound are based on the Doppler principle, which states that sound emitted from a moving source or sound reflected from a moving target will lead to a shift in the frequency of the sound. This so-called Doppler shift can be measured directly from the received signal through a continuous wave ultrasound emission (CW-Doppler), or sampled through the emission of several ultrasound pulses (PW-Doppler).

Today, Doppler ultrasound measurement is an integral part of commercial scanner systems. Conventional blood flow imaging modalities include spectral Doppler, in which the complete spectrum of velocities within one specific region is displayed. Another modality estimates the mean velocity and direction of blood in many points in a distributed region, which is encoded as a parametric color image, displayed overlaid an image of the anatomy. This latter color flow imaging (CFI) modality has proven very useful for the detection of areas of abnormal blood flow, which can be investigated further using spectral Doppler techniques. In Figure 1, the operation of both CFI and spectral Doppler techniques are shown.

Doppler and colour flow imaging

Some blood flow related student assignments

1. Model-based estimation of complex blood flow in congenital heart disease (fetus, neonates and children)

Cardiac flow patterns may reveal several kinds of cardiovascular disease. Well known examples include the detection and quantification of leaky heart valves and poor systolic and diastolic function. Conventional flow imaging with ultrasound is however limited to only measuring the velocity component along the ultrasound beam, i.e. it is a one-dimensional and angle-dependent measurement. This discrepancy limits the usefulness of Doppler ultrasound in diagnostic settings. In this work we will focus on further developing multi-dimensional flow velocity estimators based on speckle tracking, i.e. image pattern matching techniques. The main clinical application will be pediatric cardiology, with the aim to improve the depiction of complex flow patterns such as vortex and shunt flow.

The proposed multidimensional approaches proposed are however not as robust as conventional methods. Thus, the aims of this student project will be to further develop and optimize tracking algorithms within a robust framework based on the predicted motion of flow using a Kalman filter (model-based estimation).

Aims:

  • Further develop and validate robust tracking algorithms that optimally weight measurement and modelling errors (model-based estimation)
  • Test the proposed methods on simplified simulations as well as in vivo data from pediatric cardiology

Qualifications:

Knowledge of digital signal processing and Matlab or Python programming, GPU-programming (optional) 

Contact:


2. Robust blood velocity estimation based on speckle tracking

We see a great potential for providing the medical doctors with more detailed information of blood patterns by estimating the full 2D/3D blood flow velocity vector, where the current methods relying on Doppler principles are only able to give a 1D velocity component. This will be used in many different medical applications such as vascular imaging and pediatric and adult cardiology. One relevant velocity estimator is the blood speckle tracking estimator which relies on an initial (fast) block matching procedure, and a refined subsample displacement estimator step. We would like to know more about this estimator and we want to make it more robust. We are looking for a candidate to 1) Evaluate the statistical properties of the current (simple) algorithms for speckle tracking, and to develop new and more robust speckle tracking algorithms based for instance on robust least squares estimator principles for the initial block matching, and optical flow principles for the subsequent subsample estimation. Also important, we need to provide an uncertainty map to be able to mask out the more uncertain measurements.

Preferred qualifications:

  • Signal processing, estimation theory
  • Programming in either Matlab / CUDA / Python / C++

Contact:


3. Bedside computational fluid dynamics based on ultrasound imaging

There is increasing interest in using advanced computational models for blood flow based on computational fluid dynamics (CFD). By utilizing state-of-the-art GPU's it is possible to significantly speed up computations. Further, by accelerating recent mesh-less methods based on Smoothed Particle Hydrodynamics (SPH) and Lattice-Boltzmann approaches, one can more easily couple ultrasound measurements and simulations in an easier way. Our overall goal of this task is to be able to reconstruct cardiac flow based purely on measurements from ultrasound, including input from real-time segmentation tools and state-of-the-art blood flow measurements developed in our lab. To achieve high computational speed, some trade-offs are inferred, and a central task will be to investigate the right level of accuracy and speed. This assignment is a collaboration between the ultrasound group and the biomechanics group at NTNU.

Preferred qualifications:

  • Programming in Python and C++

Contact:


4. Navigated ultrasound imaging – 3-D reconstruction of (pulsatile) artery geometry and flow

Conventional ultrasound imaging of blood flow in central and peripheral arteries is today based on 2-D imaging, while pathology related to atherosclerosis is inherently three-dimensional. While real-time 3-D ultrasound is available for cardiac imaging, transducers for vascular imaging are not yet available. However, by utilizing highly accurate position sensors during scanning, it is possible to reconstruct the 3-D geometry of arteries based on multiple 2-D flow and B-mode images. In this project we will utilize recently installed navigation system based on optical and magnetic sensors to reconstruct 3-D flow in the carotid artery. This flow is highly pulsatile, and we will also incorporate information from ECG (electro-cardiogram) to also get timing information. The imaging approach will follow a recent plane-wave imaging scheme, where a high frame rate and high image quality can be achieved. Investigations will first be done using in vitro setup of known stationary and pulsatile flow. In vivo imaging in healthy volunteers will further be tries to show the potential of mapping arterial geometry and pulsatile 3-D flow patterns. 

Preferred qualifications:

  • Programming in Matlab and C++

Contact:


5. Accelerating 2D blood flow imaging

In medical ultrasound imaging, blood velocity measurements are important for the diagnostics of cardiovascular disease. Conventional blood velocity imaging is limited as it only estimates the velocity component in the ultrasound beam direction. The ultrasound group at ISB is developing a new method for estimation of 2D blood flow patterns, producing a much more intuitive visualization of blood flow. However, ultrasound is a real-time imaging modality, and the current implementation of the method is not optimized and too slow for clinical use. 

Project aims

  • Accelerating blood vector flow estimation by using GPUs, multiple CPUs or through modification of the algorithms.
  • Real-time 2D vector flow imaging!

Preferred qualifications

  • Knowledge of C/C++/Python and experience with GPU programming.

Blood flow imaging in the carotid bifurcation

Contact:


6. Dual probe 3D blood flow imaging

Conventional ultrasound imaging of blood flow in central and peripheral arteries is today based on 2D imaging, with 1D or 2D measurements of the blood velocity. However, only measurements in 3D are able to give accurate estimates of the true velocity magnitude. By utilizing two 2D probes, it may be possible to get 3D measurements of blood flow in an overlapping image plane, enabling more accurate velocity estimates and more intuitive visualization of blood flow in this plane.

Project aims:

  • Investigate the feasibility of 3D velocity estimation using two linear probes!

Preferred qualifications:

  • Knowledge of Matlab programming and digital signal processing.

Dual probe 3D blood flow imaging

Contact:


7. Robust clutter filtering by image morphing

Estimating tissue movement with a standard tissue doppler technique and image morphing.Cardiovascular diseases (CVDs) are disorders of the heart and blood vessels and include coronary heart disease, cerebrovascular disease, rheumatic heart disease and other conditions.CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause. An estimated 17.5 million people died from CVDs in 2012, representing 31% of all global deaths.

Most cardiovascular diseases can be prevented by early detection and management using counselling and medicines, as appropriate. Recent research shows that early identification of asymptomatic individuals can reduce mortality from myocardial infarction and stroke by 50%.

Ultrasound is the most widely used imaging modality to screen for CVD, since, contrary to MRI, it is a non-ionizing method. Ultrasound screening for CVDs often involves the application of Color Flow Imaging (CFI) a technique that makes it possible to visualize the blood stream velocity field. This is only possible thanks to process called clutter filtering which removes everything but the signal reflected by the blood.

Clutter filtering in the heart is a very challenging problem. The heart tissue moves with velocities which are similar to those of the blood. As a consequence the clutter filter is not able to remove all the tissue in the image or, even worse, removes some of the signal reflected by the blood.

Here at ISB, we have envisioned a technique that can potentially improve the robustness of conventional clutter filters. The technique involves the estimation of the tissue movement with a standard tissue doppler technique and image morphing.

Example of image morphing via the mesh warping: Recent Advances in Image Morphing

Aim

  • Implement the technique and test its performance on in-silico, in-vitro and in-vivo data.

Profile

  • If you like image processing and programing,
  • if you want to be involved into research,
  • if you like to boldly go where no one has gone before:

...this is your project

Requirements

  • Background in Matlab or C++.

Contact

Estimation of true flow velocity using ultrasound

Ultrasound colour Doppler is used for estimation of flow velocity in blood vessels. The quantified flow velocity is dependent on the orientation of the ultrasound propagation path relative to the orientation of the investigated blood vessel. There are different methods that can be used for estimation of true flow velocities. One approach is to do Doppler measurements of the blood vessel from different angles. The flow velocity obtained from at least two different angles can be used to provide a more correct estimate of the true flow velocity.

Estimation of true flow velocity using ultrasound

Ultrasound colour Doppler is used for estimation of flow velocity in blood vessels. The quantified flow velocity is dependent on the orientation of the ultrasound propagation path relative to the orientation of the investigated blood vessel. There are different methods that can be used for estimation of true flow velocities. One approach is to do Doppler measurements of the blood vessel from different angles. The flow velocity obtained from at least two different angles can be used to provide a more correct estimate of the true flow velocity.

Aim:

  • Compare a novel suggested simple method to other methods for estimation of true flow velocity (litterature study)
  • Implement the suggested method in Matlab
  • Perform laboratory measurements of flow
  • Analyse the performance of the method

Qualifications:

  • Matlab programming, digital signal processing. Knowledge of acoustics and ultrasound is also advantageous.

Contact:

Fusion of multi-modal cardiac data

3D echocardiogramFull 3D datasets of the heart can be acquired using different imaging modalities e.g. 3D echocardiography (3D echo), computed tomography (CT) and cardiac magnetic resonance imaging (CMR). Using image fusion the strengths of different image modalities can be combined. As such, by co-registering multi-modal datasets, a direct spatial relationship between anatomical and functional information in the underlying data is established and visualized.

Fusion of multi-modal cardiac data

3D echocardiogramFull 3D datasets of the heart can be acquired using different imaging modalities e.g. 3D echocardiography (3D echo), computed tomography (CT) and cardiac magnetic resonance imaging (CMR). Using image fusion the strengths of different image modalities can be combined. As such, by co-registering multi-modal datasets, a direct spatial relationship between anatomical and functional information in the underlying data is established and visualized.

Furthermore in the case of 3D echo the image quality has large variations between subjects, the spatial resolution varies with depth and the tissue contrast is angle dependent. One possibility of improving image to noise ratio and to extend the field of view is to acquire multiple datasets from different angles, detect corresponding features in each view and fuse the recordings in order to generate a combined volume.

The aim of the project is to develop fusion and image registration techniques to combine multiple 3D cardiac acquisitions with the goal of improving signal-to-noise ratio, spatial resolution and field of view or to improve the diagnostic process and to demonstrate their applicability during live scanning.

3D Echocardiographic CMR

Project topics:

  1. Test/adapt state of the art image registration algorithms on ultrasound and CMR data
  2. ECG based temporal synchronization of data
  3. Comparison of various fusion algorithms vs the quality of the resulting image data 

Skills (dependent on the project):

  • Knowledge of Python, Matlab and/or C++ programming
  • Desire to learn parallel computing (CUDA or OpenCL)

Contact:

Pocket size Ultrasound technology

The pocket-sized VScanThe ultrasound group in Trondheim has several ongoing projects related to pocket-sized ultrasound. The main target is to develop technology and clinical applications for these pocket-sized devices, in order to make these devices becoming the "future stethoscope". These scanners will likely be used by general practitioners and users who are less experienced with the use of ultrasound. Enabling the clinician with the possibility to "look" into the body during the examination, could possibly improve the diagnosis and treatment of patients, as well as improving the workflow in the healthcare system. The physical size of the device and the new user groups give rise to other challenges than for the regular full-size scanners.

Pocket size Ultrasound technology

The pocket-sized VScanThe ultrasound group in Trondheim has several ongoing projects related to pocket-sized ultrasound. The main target is to develop technology and clinical applications for these pocket-sized devices, in order to make these devices becoming the "future stethoscope". These scanners will likely be used by general practitioners and users who are less experienced with the use of ultrasound. Enabling the clinician with the possibility to "look" into the body during the examination, could possibly improve the diagnosis and treatment of patients, as well as improving the workflow in the healthcare system. The physical size of the device and the new user groups give rise to other challenges than for the regular full-size scanners.

1. Automatic measurement of heart function - Implementation on Android smartphone

The motion of the AV-plane, i.e.. the plane between the left ventricle and left atrium, is a sensitive marker for heart failure.  An algorithm has been developed for automatic identification of the AV plane in the ultrasound image, using image processing tools, combined with a Doppler technique to measure the motion. The task is to implement the algorithm on an Android smartphone, validate the method, and participate in clinical testing. A framework for receiving and displaying ultrasound data on a tablet device, implemented in C++, is available and can be used in this project. Only limited knowledge of Java/Android is required as a template APK is also available.  

Qualifications:

  • Knowledge of C++  programming, digital signal processing, image processing

Contact:

 

PWDoppler of heart

2. Augmented reality for cardiac and fetal applications

 Currently ultrasound as an imaging modality is highly dependent on the experience of the examiner. During acquisition, in addition to the cognitive load associated with interpreting the image on the screen, the examiner has to control the correct positioning and orientation of the transducer in order to ensure that the correct anatomical area is imaged and that the image quality is satisfactory.

By providing visual guidance through overlays, which communicate the anatomical structures being imaged, one can greatly improve the understanding of the structural arrangement of tissues during the scanning procedure. Thus it is highly desirable to assist the ultrasound examiner and as such partially alleviate the burden of image interpretation.

The aim of the project is to develop 2D/3D visualization methods that enable the clinician to find a visual correspondence between the ultrasound data being acquired and a generic anatomical mesh-model of a human heart or a model of the fetus.

A visual correspondence between ultrasound data and a generic anatomical mesh-model of a human heart or a model of the fetus.

Project topics:

  1. Augmented reality based tool for cardiac/obstetric applications
  2. Model fitting to 3D volumes or freehand acquired 2D slices
  3. Robust detection of anatomic landmarks in ultrasound data (cardiac or obstetric) 
  4. Training Android or iOS application to facilitate the learning process of students 

Skills (dependent on the project):

  • Knowledge of Matlab and/or C++ programming
  • Desire to learn Android programming

Contact:

Pulse-echo based method for estimation of speed of sound

Accurate and spatially dense measurements of sound speed in a medium could potentially be used to obtain better ultrasound image quality, better characterization of biological tissue and for monitoring of thermal ablation. To estimate the sound speed in a medium, we need to have the travel time of the sound pulse traveling a known path length. The difficulty of sound speed estimation using conventional medical imaging ultrasound transducers is that the real or true depth of the origin of the backscattered echo is unknown, as the travel time will be dependent on both the distance and sound speed.

Pulse-echo based method for estimation of speed of sound

Accurate and spatially dense measurements of sound speed in a medium could potentially be used to obtain better ultrasound image quality, better characterization of biological tissue and for monitoring of thermal ablation. To estimate the sound speed in a medium, we need to have the travel time of the sound pulse traveling a known path length. The difficulty of sound speed estimation using conventional medical imaging ultrasound transducers is that the real or true depth of the origin of the backscattered echo is unknown, as the travel time will be dependent on both the distance and sound speed.

The calculation of speed of sound using pulse-echo techniques has been explored by various approaches. We have suggested a method using the recorded partial time delay between receivers to calculate the speed of sound of the medium.

Aim:

  • Compare the given method to other published methods for estimating speed of sound (litterature study)
  • Implement the method in Matlab
  • Evaluate the method using synthetic data
  • Performing laboratory measurements
  • Analyse the performance of the method

Qualifications:

  • Matlab programming, digital signal processing. Knowledge of acoustics and ultrasound is also advantageous.

Contact:

Ultrasonic imaging through solids

In Non Destructive Testing (NDT), process monitoring, and condition monitoring ultrasound is an important method. for many cases ultrasonic based inspection has to be done through a hard wall, made by e.g. metal or plastics. In this project such imaging shall be realized with an ultrasound scanner, the Faculty of Medicines lab scanner.

Ultrasonic imaging through solids

In Non Destructive Testing (NDT), process monitoring, and condition monitoring ultrasound is an important method. for many cases ultrasonic based inspection has to be done through a hard wall, made by e.g. metal or plastics. In this project such imaging shall be realized with an ultrasound scanner, the Faculty of Medicines lab scanner.

One shall implement beamforming adapted for the above described situation and neccessarry image processing to investigate the achieved image quality.

Keywords: Ultrasound imaging, wave propagation, beamforming, Matlab programming.

Contact:

SURF Imaging Topics

Noise suppression for imaging of soft plaque.SURF Imaging is a new method for ultrasound imaging under development at the Department of Circulation and Medical Imaging. The methods most important concept is to emit two ultrasound pulses at the same time, one conventional high frequency imaging pulse and an additional low frequent manipulation pulse which modifies the propagation and scattering of the imaging pulse.

SURF Imaging Topics

Noise suppression for imaging of soft plaque.SURF Imaging is a new method for ultrasound imaging under development at the Department of Circulation and Medical Imaging. The methods most important concept is to emit two ultrasound pulses at the same time, one conventional high frequency imaging pulse and an additional low frequent manipulation pulse which modifies the propagation and scattering of the imaging pulse.

This opens for exciting new imaging possibilities as f.ex. noise suppression for imaging of soft plaque (1st image), and enhanced contrast agent imaging for cancer detection (2nd image).

Enhanced contrast agent imaging for cancer detection.

Several topics are available, also in collaboration with departments in cybernetics, signal processing, computer science, acoustics, electronics, and mathematics at NTNU.  Example topics are related to nonlinear ultrasound propagation and signal processing, mathematical topics on simulation of nonlinear wave propagation and scattering, GPU parallel programming for real time processing, and multiband transducer designs.

Why does the manipulation pulse make a difference?

Both the scattering and the sound propagation speed is pressure dependent. So applying a manipulation pressure will alter these properties and an imaging pulse travelling in a compression phase of the manipulation wave will be slightly different from a pulse travelling in the rarefaction phase. This difference can be used to extract more information about the tissue and thus enables more advanced processing schemes. For more information on the method take a look at the SURF imaging page.

A group of researchers works at the department with SURF imaging and we are looking forward to offer you a project or thesis in one of the most exciting fields of medical ultrasound imaging! 

Skills

In general students will gain knowledge in the following areas:

  • Wave propagation (Ultrasound theory)
  • Programming (Matlab, C, C++, Python)
  • Signal processing
  • Medicine
  • Literature study and writing of articles
  • team work
  • research and development

Tailoring of topics

Below you'll find a list with available topics. They are all relevant both for master thesis as well as project work. The descriptions are kept quite general and since they anyway will be individually tailord to your interest f.ex. a focus on lab-work, programming, simulations, theoretical and algorithm development ...
Please get in contact with the corresponding supervisors! They'll help you finding the perfect topic for and with you.

Topic: Improved detection of ultrasound contrast agents

The ultrasound echo from blood is very weak compared to the echoes generated by tissue. In many situations it is desired to detect and image blood in the smallest blood vessels. To detect blood in these capillaries often an ultrasound contrast agent is injected into the blood circulation of a patient. These contrast agents are gas-bubbles with a typical diameter of 3µm which give en enhanced ultrasound echo and are transported with the blood. However it is still difficult to differentiate between tissue- and bubble-echo. This is especially important in the diagnosis and treatment of cancer where good imaging of the vessels and their structure is curcial. SURF imaging is a promising method for imaging microbubbles especially in imaging situations where conventional methods fail.

The topic will contain optimalizing, testing and verification of the method and the algorithms behind. Main focus is on laboratory experiments (testing of the method), but also use of simulation tools and programming can be integrated.

Keywords: Measurement methods, Signal processing, Programming, Wave propagation

Topic: Reverberation suppression

Image quality in ultrasound is very patient dependent. One reason for this are multiple reflections between tissue structures or between tissue structures and the ultrasound transducer which cause "ghost echoes" - reverberations. In the best case reverberations become visible as a discernable distinct copy of a tissue structure in shallow depths but more often and more serious a haze of noise is spread over the image.
This noise in the image causes problems in diagnosis in nearly all applications where ultrasound images are used for diagnostics.

The topic contains work on beamforming, simulations and phantom design (design test bodies) for better noise suppression. This comprises in most cases work with software tools and can also comprise experimental work in the ultrasound lab.

Topic: Estimation of non-linear scattering

Calcium particles are building up in the tissue in a number of medical conditions. In for example the diagnosis of breast cancer the physician is interested in calcium particles as they may indicate malignancy. Calcium is visualized very good in X-ray imaging, but not that good in ultrasound.
Improved imaging of calcium particles would directly give better diagnostics and guidance of tissue biopsies.

The topic contains experimental work in the lab, simulations, signal processing and estimation.

Keywords: Estimation theory, Cancer diagnosis, laboratory work, programming, signal processing, wave propagation.

Topic: Transducer for SURF Imaging

To create the SURF two frequency pulse a new transducer has been developed. The transducer consist of a stack of at least two piezoelectric layers, one for the low frequency pulse and one for the high frequency pulse, and layers inbetween the two for mechanical isolation and matching between the two layers. A couple of prototypes transducer arrays have been manufactured, and are succesfully used for imaging. However there are several issues to be investigated for the transducer design, amongst others; bandwidth of the passbands, internal reverberations, mechanical cross coupling, electrical matching to the scanner, non linear behaviour of the transducer.
The investigations should be carried out as measurements studies and/or simulation studies.

Supervision

The students have Bjørn Angelsen as their main or co-supervisor.

Main supervisor

Co - supervisors

Ultrasound Mediated Drug Delivery

Figure 1: Micrograph of a capillary (red), nanoparticles (blue), free drug molecules that have entered into cells (green), and cells without drugs (black).Ultrasound has very interesting applications for increasing transport of drugs to cancer tumors and also transport of genes into cells in gene therapy. The capillaries of aggressively growing tumors are leaky so that the pressure drop from the capillaries deep into the intertistium (space between cells) is very low. Transport of drugs from the capillaries to the cells is therefore mainly produced by diffusion, which is a slow process. Ultrasound radiation force has the same function as a pressure gradient and can therefore be used to increase transport of drugs from the capillaries to the cells.

Ultrasound Mediated Drug Delivery

Figure 1: Micrograph of a capillary (red), nanoparticles (blue), free drug molecules that have entered into cells (green), and cells without drugs (black).Ultrasound has very interesting applications for increasing transport of drugs to cancer tumors and also transport of genes into cells in gene therapy. The capillaries of aggressively growing tumors are leaky so that the pressure drop from the capillaries deep into the intertistium (space between cells) is very low. Transport of drugs from the capillaries to the cells is therefore mainly produced by diffusion, which is a slow process. Ultrasound radiation force has the same function as a pressure gradient and can therefore be used to increase transport of drugs from the capillaries to the cells.

The leaky capillary walls opens for packaging the drugs into nanoparticles (diam ~ 100 nm) that leak out of the tumor capillaries, but not out of normal capillaries, hence protecting normal tissue against the drug. The 1st Figure shows a micrograph of a capillary in red, with some nanoparticles in blue, and free drug molecules that have entered into cells in green. The black areas are cells without drugs. We note that the nanoparticles are found close to the capillaries due to lack of pressure gradient.

Figure 2: Ultrasound radiation force is very useful to improve the transport of particles and molecular drugs away from capillaries.Ultrasound radiation force is therefore very useful to improve the transport of particles and molecular drugs away from the capillaries, as illustrated in the 2nd Figure.

Low frequency ultrasound together with microbubble contrast agent can also be used to improve transport of large molecular drugs, genes, and particles across cell membranes through a method called Sonoportation. This method can also be used to improve transport of drugs into brain tumors, that is hampered due to the blood brain barrier of the cerebral capillaries. Multifrequency ultrasound hence has many interesting applications in cancer and gene therapy, presenting many interesting thesis topics within nonlinear ultrasound propagation and tissue interaction, design of high power multiband ultrasound transducer arrays. The work is done in collaboration with professor Catharina Davies at Department of Physics, and also other groups in acoustics and mathematics at SINTEF and NTNU for simulation and design of acoustic experiments in relation to drug delivery probelms. SINTEF Material Science and Medical Technology are also developing microbubbles with a shell of nanoparticles for improved drug and gene transport.

There are several interesting Master and PhD topics in this field, ranging from

  • multi-frequency ultrasound acoustics and transducer arrays for imaging of particles and stimulated transport and breakage of the particles
  • signal processing for multi-frequency ultrasound imaging (SURF Imaging) of the particles
  • combined optical imaging of particles with ultrasound mediated drug delivery
  • experimental studies of ultrasound mediated transport and breakage of gas micro-bubbles and drug encapsulating nano-particles in lab models and small animal tumor models

Contact:

Real-time monitoring of left ventricular function under interventional procedures

Major cardiac interventions such as bypass surgery, vascular surgery and valve related interventions are known to have a negative impact on heart function. As of today patient monitoring during the intervention is performed by a combination of vital signs monitoring (i.e. blood pressure, heart rate, blood oxygen saturation) and clinical observation by the anesthesiologist. Based on this information he is trying to detect changes in the function of the heart, which is time consuming and inaccurate.

Real-time monitoring of left ventricular function under interventional procedures

Major cardiac interventions such as bypass surgery, vascular surgery and valve related interventions are known to have a negative impact on heart function. As of today patient monitoring during the intervention is performed by a combination of vital signs monitoring (i.e. blood pressure, heart rate, blood oxygen saturation) and clinical observation by the anesthesiologist. Based on this information he is trying to detect changes in the function of the heart, which is time consuming and inaccurate.

The aim of this project is to develop an algorithm capable of detecting changes in the function of the heart and specifically of the left ventricle, based on blood pressure, ECG measurements as well as echocardiographic parameters obtained during continuous automated monitoring, which are proven to correlate well with the function of the heart.

Objectives:

  • Extend existing data transfer and logging tools by adding support for the computation and tracking of parameters related to left ventricular function
  • Identify which parameters are best suited for identifying early signs of changes in left ventricular function
  • Develop machine learning based tools for automatic detection of functional changes
  • Validate the methods on recorded patient data

Skills:

  • Knowledge of Matlab or C++ programming

Contact:

Fighting Cancer with CW Shear-Wave Elastography

Breast cancer is the most common cancer in women worldwide, with nearly 1.7 million new cases diagnosed in 2012 (second most common cancer overall). This represents about 12% of all new cancer cases and 25% of all cancers in women. Early detection remains the cornerstone of breast cancer control. The majority of deaths (269 000) occur in low- and middle-income countries, where most women with breast cancer are diagnosed in late stages.

Fighting Cancer with CW Shear-Wave Elastography

Breast cancer is the most common cancer in women worldwide, with nearly 1.7 million new cases diagnosed in 2012 (second most common cancer overall). This represents about 12% of all new cancer cases and 25% of all cancers in women. Early detection remains the cornerstone of breast cancer control. The majority of deaths (269 000) occur in low- and middle-income countries, where most women with breast cancer are diagnosed in late stages.

Ultrasound is used as the first screening test for breast cancer. However, in early stages, tumorous masses are difficult to detect due to lack of contrast. Ultrasonic elastography brings a new dimension into cancer detection by imaging the tissue stiffness rather than its reflectivity. New techniques have been recently proposed using CW vibration fields. Here at ISB we are developing a technique that can potentially increase the resolution and accuracy of stiffness maps. We utilize high frequency acoustic fields (1 to 5 kHz) and a detection technique based on the k-space transform. Fig.1 shows a numerical simulation of the estimated shear-wave velocity map when an acoustic vibration field of 2500 Hz is used.

Figure 1a. Detected velocity field.Figure 1b. Estimated shear wave velocity map.

Video:

Aim:

We would like to develop this technique further by

  • Developing a 2 kHz shear wave acoustic vibrator, and
  • using 3D ultrasound to image the shear-wave vibration field.

Profile:

We look for someone that:

  • likes experimental work and developing technology,
  • would like to get hands on scientific procedures, and
  • (may be) get her/his name on a paper.

Requirements:

  •     Background in signal processing or electronics is desirable.

Contact:

   Alfonso Rodriguez-Molares Ph.D., Senior Engineer

   Sebastien Salles Ph.D., Postdoc

Adaptive clutter filtering for coronary heart disease

In coronary heart disease (CHD) plaque builds up inside the coronary arteries and blocks the supply of oxygen to heart muscle. And if the supply of oxygen to the heart fails… yeah, that’s no good. CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause. An estimated 17.5 million people died from CVDs in 2012, representing 31% of all global deaths.

Adaptive clutter filtering for coronary heart disease

In coronary heart disease (CHD) plaque builds up inside the coronary arteries and blocks the supply of oxygen to heart muscle. And if the supply of oxygen to the heart fails… yeah, that’s no good. CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause. An estimated 17.5 million people died from CVDs in 2012, representing 31% of all global deaths.

Most cardiovascular diseases can be prevented by early detection and management using counselling and medicines, as appropriate. Recent research shows that early identification of asymptomatic individuals can reduce mortality from myocardial infarction and stroke by 50%.

Ultrasound is the most widely used imaging modality to screen for CVD, since, contrary to MRI, it is a non-ionizing method. Ultrasound screening for CVDs often involves the application of Color Flow Imaging (CFI) a technique that makes it possible to visualize the blood stream velocity field. This is only possible thanks to process called clutter filtering which removes everything but the signal reflected by the blood.

Clutter filtering in the heart is a very challenging problem. The heart tissue moves with velocities which are similar to those of the blood. Consequently the clutter filter is not able to remove all the tissue in the image or, even worse, removes the signal reflected by the blood. Here at ISB, we have envisioned a technique that can potentially improve the robustness of conventional clutter filters. The technique involves the estimation of the tissue movement with a standard tissue doppler technique and then subtracting a deformed version of the image in time.

Aim

  • Implement the technique and test its performance in simulations and experiments.

Profile

We look for someone that:

  • likes signal processing and programing,
  • would like to face a tough research problem, and
  • is not easily demotivated.

Requirements

  • Background in Matlab or C++.

Contact:

Contact ISB

  • E-mail: isb-post@medisin.ntnu.no
  • Visiting address: St.Olavs Hospital, Prinsesse Kristinas gt. 3, Akutten og Hjerte-lunge-senteret, 3.etg. (see map)
  • Postal address: NTNU, Fakultet for medisin og helsevitenskap, Institutt for sirkulasjon og bildediagnostikk, Postboks 8905, 7491 Trondheim, Norway
  • Delivery address: NTNU/ISB, Heggstadmoen 51, Intern: Akutten og Hjerte-lunge-senteret, 3.etg. øst, 7080 Heimdal, Norway