Category Archives: Research

Microbubbles and focused ultrasound cure tumours in mice

Catharina de Lange DaviesBlogger: Catharina de Lange Davies, professor Department of Physics, NTNU

A prerequisite for successful chemotherapy is that the drugs reach its target, and that damage to healthy tissue is limited. However, when drugs are injected into the blood, less than 1% of the drugs accumulate in tumours. Microbubbles combined with focused ultrasound shows great promise in enhancing delivery of nanoparticles and drugs thereby improving cancer therapy. Focused ultrasound and nanoparticles can also be used to temporarily open the blood-brain barrier thereby allowing nanoparticles and drugs to enter into brain tissue, which enables treatment of brain disorders. At the Department of Physics, NTNU, we are using two types of new microbubbles to improve the delivery of nanoparticles and drugs in combination with focused ultrasound. Continue reading

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Can the growth rate of brain tumours help predict survival?

Asta HåbergAnne Line StensjøenBloggers: Anne Line Stensjøen, PhD Candidate, Department of Neuromedicine and Movement Science (INB), and Asta Håberg, Professor and Centre Director, Centre of Innovative Ultrasound Solutions (CIUS)

Glioblastomas are tumours that originate from brain tissue. It is both the most common and most aggressive type of brain tumour. The median survival at group level is only 10 months for glioblastoma patients in Norway, but it is difficult to predict how long an individual long patient will survive.

How fast brain tumours grow is important to know to make the best decisions with regard to treatment. Tumour growth can also tell us something about how aggressive the tumour is, and perhaps be used as a marker of prognosis. It has been difficult to assess tumour growth because it requires at least two magnetic resonance images (MRIs) of the brain before treatment is started. Continue reading

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Beamforming – An international challenge

alfonsoBlogger: Alfonso Rodriguez-Molares, Postdoc and Senior Engineer, Department of Circulation and Medical Imaging and Centre for Innovative Ultrasound Solutions (CIUS).

A revolt is being stirred up in the beamforming world, and CIUS is among the insurgents.

For the first time in history a beamforming challenge was organized in the field of Medical Ultrasonics.

“What is beamforming?”, I hear you say. Beamforming is what bats do. They send an ultrasound signal which gets reflected at targets in front of them, such as prey (insects, fruits) or obstacles (watch out for that tree!). The reflected signal comes back to the bat ears and then the bat knows where the targets are and how to move around. But how does the bat know that? That’s where beamforming comes into play. Beamforming is the process by which temporal data (what the bat hears) is converted into spatial maps (where things are in the world). The bat does it with specialized ears that filter sound differently depending on the direction: up sounds differently than down, left than right, close than far. The same trick is used by other animals. Dolphins use an acoustic lens to direct ultrasound in the forward direction, oilbirds use echolocation to navigate through tress and caves in complete darkness, blind people can learn to navigate around the world by clicking their tongues. All that’s beamforming. Continue reading

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Improvements in ultrasound transducer design and manufacturing

Martijn Frijlink. Photo: Kari Williamson NTNUBlogger: Martijn Frijlink, Associate Professor,
Centre for Innovative Ultrasound Solutions (CIUS) and University College of Southeast Norway



All ultrasound technologies in health care, maritime, and oil & gas make use ultrasonic transducers. For this reason, transducer design is a key research task of the Centre for Innovative Ultrasound Solutions (CIUS).

Ultrasonic transducers are devices that convert electrical signals into mechanical vibrations and vice versa at frequencies above the hearing limit of 20 kHz. This is comparable to loudspeakers and microphones in the audible frequency range. Ultrasonic transducers are also called ultrasound probes. So, in other words, the probes transmit and receive sound waves beyond the hearing limit

Different application areas require different types of probes in the frequency range from 20 kHz to approximately 10 MHz. The core of a probe conventionally consists of a layer of piezoelectric material, which is a material that deforms when an electric field is applied, and that can generate an electric signal when a mechanical pressure is applied. To increase the efficiency to transmit ultrasound waves into the transmission medium, e.g. water, gel, the human body, or an oil or gas pipeline, the probe needs to be matched acoustically to the propagation medium. This is typically done by applying acoustic matching layers, which are thin layers with well-defined thicknesses down to the micrometre range and with appropriate acoustic properties. Transducers can contain one to several thousand acoustic elements. All these elements need to be electrically connected to transmit and/or receive electronics. All these aspects make the design of ultrasonic transducers a multidisciplinary task that include physics, electronics, mechanics, and materials.

At the Department of Micro- and Nanosystem Technology, which is part of the Faculty of Technology and Maritime Science of the University College of Southeast Norway at Campus Vestfold in Horten, we are investigating different aspects of probes for applications in both medical, maritime, and industrial fields. Our ultrasound laboratory workshop allows the manufacturing of special custom-designed prototype ultrasound probes in the frequency range from approximately 1 to 10 MHz. These ultrasound probes can be either a single-element probe (one transducer element to transmit and receive the sound, see this Wiki article on Doppler fetal monitor) or an array probe consisting of multiple transducer elements that allows steering of the transmitted and received ultrasound beam.

A prototype transducer stack.

An example of a prototype transducer stack, created and imaged at the acoustic lab at HSN.

One research topic that is under investigation as part of CIUS is the design and manufacturing of a dual frequency transducer for medical purposes. A dual frequency transducer can send and receive both lower and higher frequency sound. A potential application is the manipulation and detection of ultrasound contrast agents, which are tiny gas spheres that can be injected in the blood circulation for e.g. blood flow imaging. The dual frequency probe would allow for transmitting and receiving at different frequency ranges, but through the same probe surface. Such probe design could consist of several active piezoelectric layers, which can result in complex vibration modes and a more complex manufacturing procedure.

Another topic under investigation is self-heating of probes. In transmit, all electrical energy that is consumed but not transmitted into the transmission medium, is lost as heat within the probe itself. This leads to heating of the probe, and can even result in probe failure. The hypothesis is that theoretical investigation of the thermal principles behind this, and accurate modelling and measurements of temperature distributions within real ultrasonic probes, can lead to better understanding and methods in how to reduce heating problems that are currently experienced in some industrial applications.

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What the immune system is up to while you’re holding your breath

Ingrid EftedalBlogger: Ingrid Eftedal, Principal investigator
Barophysiology research group, Department of circulation and medical imaging



White blood cells are essential components of the immune system. Without these cells we would not stay healthy for long on a planet where infections thrive. But what are these cells up to when we’re not sick? They are present. And they are active, at all times.

Lean back and breathe in. Hold your breath. It can’t get much easier; what could there possibly here for a scientist to study? Well, there is something.

Evolution has shaped us for the environment we live in, and our environment is never completely static. The immune system is involved in rapid biological adjustments that protect us from harm caused by environmental perturbations. Some perturbations are of a cyclic nature, like those that are linked to the earth’s rotation around the sun and its own axis. In an elegant study published in the journal Nature in 2015, English and German scientists identified variations in the immune system that are perfectly aligned with the seasons. Actually, our bodies appear to lie slightly ahead of the seasonal changes: we appear to have a biological memory that fine-tunes the immune system just before the seasons change. Since many common infectious diseases appear in a seasonal pattern, this is an amazing adaptation for life on planet earth. If we speed the cycle up a bit, related effects have been observed over the 24 hrs cycle.

So the immune system shows cyclic variation.

What happens if we speed it up to the cycle of our breath?

Most of the time, we breathe without thinking about it. Our cells need oxygen for energy production, and once we have filled our lungs with air, it is the circulatory system – i.e. the heart, blood vessels and blood – that distributes oxygen to the cells in all parts of our body. We can all voluntarily hold our breath for a while, but some people do this better than the rest. Freedivers dive while holding their breath; the best of them can hold their breath for over 10 minutes.

Freediving competition.

Eleven-time free-diving world champion Goran Colak during a bout of static apnea; timed breath-holding while immersed in water .We have used blood samples from elite free-diving athletes to examine how white blood cells of the immune system responds to acute reduction in blood oxygen levels. The photo is used with Goran Colak’s permission.

In order to understand how white blood cells respond to an altered breathing pattern, we studied some of the world’s best free-diving athletes. We used a simple design: blood samples were drawn from contestants at an international free-diving competition before start, and then again one and three hours after completion of a series of dives where the athletes either lay face down in water or swam close to the surface for as long as they could.

Then the samples were transported to the NTNU Genomic Core Facility where total gene expression in the athletes’ white blood cells was measured by a method called full genome microarray analysis. The analysis results were striking: the activity of more than 5000 genes changed in response to the simple effort of breath-holding. This is almost ¼ of all genes found in human cells. With this amount of data we could dig deeper into cellular biology and calculate which specific types of white blood cells that reacted to breath-holding, and also see finer details in the biological processes going on within the cells.

Graph showing white blood cell types in freedivers.

The figure shows a selection of white blood cell types in samples taken from athlete free-divers. Blue boxes are cell amounts prior to diving, whereas the red and green boxes show the same cells one and three hours after diving. The main changes identified were a marked increase in the amount of neutrophil granulocytes, whereas two types of lymphocytes; CD8-postivie cells and natural killer (NK) cells, decreased. Calculations of relative amounts of specific white blood cell types were done by mathematical deconvolution of global blood gene expression data.

The most striking finding we did was a marked increase of the white blood cell type neutrophil granulocytes. These blood cells are programmed for rapid response when the body perceives attacks from intruders; the neutrophils are capable of killing invading cells simply by eating them. But they also have another interesting trait that emerges when oxygen levels drop: neutrophil granulocytes are evolutionary old-timers that stem from an era when the atmosphere contained less oxygen than now, and their modern offspring still prefer environments where the oxygen levels are low. White blood cell types that use more oxygen – like lymphocytes – were less active in blood drawn after the athletes held their breath. What we observed are likely to be traces of evolutionary history still embedded in our immune system, visible when oxygen levels change. The study was published in November 2016 in the journal Physiological Genomics.

This study was done on healthy athletes.

Can it be relevant for understanding of human diseases?

Healthy people normally don’t have to worry about oxygen, but for common diseases like chronic obstructive lung disease (COPD) and sleep apnea, the body’s oxygen supply is limited. These diseases are associated with persistent inflammatory conditions, and increased risk of infections; both indicative of an impaired immune system. If we can use data from healthy individuals to distinguish secondary effects of low oxygen levels from the primary pathology of the disease, this may in turn be helpful for prevention and treatment strategies.

– And breathe out.

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Filed under Blood, Inflammatory and Immune System, Research

Exploiting nonlinear distortion to switch from black and white to colour in underwater acoustic imaging

Fabrice_PrieurBlogger: Fabrice Prieur, PostDoc,
University of Oslo and Centre for Innovative Ultrasound Solutions (CIUS)


When ultrasound propagates through water nonlinear effects come into play and distort the signal originally transmitted (Figure 1). The effect of this distortion can be seen as a transfer of energy around what is called “harmonic frequencies”. For example if the signal originally transmitted has a frequency of 1 MHz, after nonlinear distortion it will show components around 1 MHz, but also 2 MHz, 3 MHz, etc. (Figure 1).

The component around 1MHz is called the fundamental and those around 2 MHz, 3 MHz, etc. are called second harmonic, third harmonic, etc. A “monochromatic” signal (we use this term from the optical field to qualify a pure tone with one single frequency) becomes “polychromatic”. One could say that nonlinear effects “add colours” to a signal. By “listening” around these harmonic frequencies additional information can be extracted.

Graphs showing before and after nonlinear distortion.

Figure 1: Signal (top) and its frequency content (bottom) before (left) and after (right) nonlinear distortion. The frequency of the signal before distortion is 1 MHZ. It is a “monochromatic” signal. After distortion, its frequency spectrum shows components around the upper harmonic frequencies: 2 MHz, 3 MHz, etc. The signal is now “polychromatic”.

In underwater acoustics however its applications seem to be reduced to the “parametric arrays”. These arrays usually quite large in size explore another effect nonlinearity that creates very directive sound at low frequency capable of penetrating deep into the ocean bottom. This type of sonars are most often used for “seeing beyond the ocean floor” also called sub-bottom profiling. There are today opportunities for using nonlinearity in applications such as seabed imaging or fish finding in ways similar to what is done in medicine with THI: second harmonic imaging in underwater acoustics.

It is surprising that Thomas Muir who first thought about using nonlinearity in underwater acoustics imaging did not limit himself to the second harmonic but went all the way to image targets using the fifth harmonic when we know that the sound level decreases by at least 6 dB per harmonic.

Images from first trials of harmonic imaging in underwater acoustics.

Figure 2: First trials of harmonic imaging in underwater acoustics by Muir: “Nonlinear effects in acoustic imaging” 1980. First five harmonics used to image a floating barge and a cylinder.

I had the chance to meet Tom Muir recently at a conference. I told him that we were trying to take his pioneering work further and mentioned his article on harmonic imaging to which he replied “this paper was quickly forgotten” but he was well aware that he tried harmonic imaging before it became widely spread in medical imaging.

Fabrice Prieur and Tom Muir.

Figure 3: Thomas Muir (right) who pioneered the first trials on harmonic imaging in underwater acoustics.

Only six years ago when we first started some experiments to prove the feasibility of second harmonic imaging using echo-sounders (simple sonars for fish finding) we were limited by the technology. The bandwidth (frequency range) of the system did not allow receiving the second harmonic and separate systems needed to be used for transmit and receive. Today the systems bandwidth has exploded going from 70 to 140 kHz or even from 200 kHz to 400 kHz making second harmonic imaging easily available.

EM2040 multi-beam echo-sounder from Kongsberg Maritime

Figure 4: EM2040 multi-beam echo-sounder manufactured by Kongsberg Maritime. (Image courtesy of Kongsberg Maritime)

Using the second harmonic in addition to conventional imaging could not only improve the image quality but bring additional information about what we are imaging. Indeed when directing sound towards an object or an animal the level of sound reflected by it depends on the frequency of the incoming sound. Comparing the level of the sound received at the fundamental and second harmonic frequencies could help identifying targets.

Gathering information contained in the echo of the fundamental frequency and of the upper harmonics would be a bit like switching from black and white to colour television. Preliminary tests on more advanced sonars used for bottom mapping (multi-beam sonars) using the second harmonic seem to be very promising. So let us turn the colours on!

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CEMIR received Young Research Talents grant (FRIPRO) from the Research Council of Norway

Two researchers at CEMIR, Atle Granlund and Richard Kandasamy have received the “Young Research Talents” – grants that is a part of the FRIPRO-funding (Norwegian link) for researchers early in their career.  FRIPRO is an open, national competitive arena that covers all fields of research. It aims to promote scientific quality at the forefront of international research, boldness in scientific thinking and innovation, careers for young research talents and mobility for researchers early in their career. FRIPRO aims to contribute to strengthen Norway’s national knowledge base by funding broad-based, independent research, that is a prerequisite for all other research and is essential for future industrial development and for policymaking. Continue reading

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Filed under Inflammatory and Immune System, NTNUmedicine, Research

If van Gogh was a pathologist…

Eugene KimBlogger: Eugene Kim, Post Doctor
MR Cancer Group, Department of circulation and medical imaging




This image won the prize for Best Scientific Image at the 8th International PhD Conference in Medical Imaging 2016:

Inspired by Vincent van Gogh’s signature bold, sweeping brush strokes, this contemporary piece evokes a meteor shower back-dropped by the majestic Milky Way stretching across the midnight sky.

It is a false-color image of a human breast cancer tissue section in which blood vessel walls and proliferating (growing/replicating) cells were labeled using immunohistochemistry. A digital image of the tissue section was acquired with a microscope. Then, a computer algorithm was used to segment the image into different classes or types of cellular and tissue components. Each color represents a different class (e.g., orange = blood vessel and yellow = proliferating cell).

A false-colour image of a human breast cancer tissue. Image: Eugene Kim

Technical details

The digital image of the human breast cancer tissue section was acquired at 40x with an Olympus VS120 slide scanner. K-means clustering was performed in MATLAB to segment the image into the different classes. This was part of a larger algorithm to automate the tedious task of counting proliferating blood vessels.

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Tuberculosis – a complex enigma

Blogger: Jane Atesoh Awuh, Postdoctoral Fellow, Department of Cancer Research and Molecular Medicine and Centre of Molecular Inflammation Research (SFF-CEMIR).20161125_133429 crop

Most often we become passionate and involved in issues in this life for very personal reasons. I am particularly drawn to infectious diseases because I hail from a society that is plagued by one kind of infection or the other. If you are not killed by one infectious disease you will be by the other, and if not by disease, it will be by war or hunger. I know two relatives who died of tuberculosis, one of them only a couple of months ago. Tuberculosis (TB) is still a disease of poverty although there is increasing incidence even in developed countries. HIV and TB are a dangerous liaison wherein HIV infects and destroys the very cells that should protect us from TB. These diseases are still considered shameful and surrounded by stigma. Continue reading

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Filed under Infection, Inflammatory and Immune System, NTNUmedicine, Research

Fusion makes a difference – also in the prostate!

ansattebilde.may-britt.tessemailin falkmo hansenBloggers:  Ailin Falkmo Hansen (PhD candidate) and May-Britt Tessem (Research Scientist), MR Cancer group


Movember is around with a “trøndersk” spirit on Facebook, Instagram, and the city is filled with mustaches in different shapes and varieties. The goal is increased awareness of men’s health and prostate cancer – a disease we in the MR cancer group want to understand better.

vevsbit og MR

Prostate tissue samples are stored in liquid nitrogen prior to MR spectroscopy analyses (photo: Geir Mogen/NTNU)

How can cancer metabolism provide important information about prostate cancer?

Scientists around the world have shown that changes in metabolism are important characteristics of cancer. We have studied how metabolism is altered due to cancer and how metabolism is changed owing to cancer aggressiveness. Previously, we have found that the two molecules citrate and spermine may be markers for prostate cancer and also can reveal information about aggressiveness.

Prostate cancer is a heterogeneous type of cancer, and this is of importance for treatment and prognosis of patients. However, today there are no reliable methods for assessment of type of prostate cancer. Researchers world-wide are therefore searching for new methods that may provide diagnostic and/or prognostic information. Presence of the fusion gene TMPRSS2-ERG have been suggested to be a candidate method for risk stratification, and in a recently published study we investigated the link between prostate cancer metabolism and TMPRSS2-ERG.

Continue reading

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