Tag Archives: ISB

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.

Leave a Comment

Filed under NTNUmedicine, Other, Research

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.

Leave a Comment

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!

Leave a Comment

Filed under NTNUmedicine, Other, 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.

Leave a Comment

Filed under Cancer, 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

Leave a Comment

Filed under Cancer, NTNUmedicine, Research

CIUS fall conference day 2016

The second CIUS full-day conference held on 23 November 2016 in Trondheim, attracted near 80 participants representing CIUS researchers, partners, collaborators and international speakers.  The day had a varied programme and ample opportunity for networking across work packages, institutions, and fields of speciality.

CIUS director Asta Håberg opened the day before leaving the floor for the invited speakers Dr Alan Hunter from University of Bath, and Dr Hua Wang from MIT.

Presentations by Hunter and Wang. Photos: Kari Williamson/NTNU

Dr Hunter spoke on the topic “Underwater crime scene investigation for the London Metropolitan Police”, where the challenge is to develop an autonomous, compact, easy-to-use and affordable sonar vessel for finding missing persons and objects related to crime. He took us through the progress in the project so far, and future challenges, like identifying small objects.

Dr Wang’s presentation on “Seismic Propagation in Borehole Environment” took us through the use of wave dispersion characteristics by modelling of single and dual cased wells.  He presented a novel method for depicting and characterizing bore holes, even through double steel layers, using ultrasound.

After a quick update on plans for the CIUS website and intranet by web- and communications officer Kari Williamson, it was time for speed updates. The topics ranged from improving ultrasound technology and image analysis to clinical applications. See the programme below for details.

Speed updates. Photos: Kari Williamson/NTNU

The partner presentations ranged from open heart surgery applications and innovative projects, to the use of portable ultrasound at the patient bedside, also by non-expert users.

First speaker was Erik Swensen, Vice President R&D at Medistim, who talked about the use and challenges of developing reusable ultrasound probes for monitoring vessel patency in open heart, peripheral and transplant surgery. He was followed by Svein-Erik Måsøy, CEO Inphase Solutions, who talked about innovation projects including using ultrasound for wireless transfer of information and power as well as for use in quality assurance. The last speaker in this section was Håvard Dalen, Professor NTNU and Senior Consultant Cardiology St. Olavs Hospital, who showed how portable ultrasound devices can be used with great success by medical students, medical residents and nurses, and how it improves diagnostic accuracy, and thereby reducing time to treatment

Partner updates. Photos: Kari Williamson/NTNU

The final session saw updates from academia with Fabrice Prieur, Postdoc at UiO, talking about the use of 2nd harmonics, which is commonly used in medical ultrasound for SONAR imaging (non-linearity and its challenges). He demonstrated that the use of 2nd harmonics provides additional information also in SONAR.  Lasse Løvstakken, Professor NTNU, taking us through the latest in Doppler, software beamforming, functional ultrasound imaging and 3D tracking. CIUS Board Director and Programme Manager at GE Healthcare, Eva Nilssen, concluded the conference with a summary of the day.

Closing sessions. Photos: Kari Williamson/NTNU

The next CIUS conference day will be held in the last week of April and by request from our partners, the CIUS spring meeting will be extended to 1.5 day to get more time for workshops and partner-academia interaction.

The presentations will be made available on the CIUS intranet.

The programme:

  • Opening and presentation of CIUS’ results for 2016 and plans for 2017 (Professor Asta Håberg)
  • Underwater crime scene investigation for the London Metropolitan Police (Professor Alan Hunter, University of Bath, UK)
  • Seismic Propagation in borehole environment (Dr. Hua Wang, MIT, USA)
  • Presentation of CIUS intra- and internet pages (Kari Williamson, web- and communications, CIUS)
  • Speed updates:
    • Optimisation of Ultrasound Pulses for Second Harmonic Imaging, Thong Huynh, HSN
    • Experimental Evaluation of Broadband Wave Propagation in Plates, Andreas Talberg, NTNU
    • Deep learning, Erik Smistad, NTNU/SINTEF (Read Smistad’s blog on the same topic.)
    • 3D Vector Flow, Morten Smedsrud Wigen, NTNU
    • Improving Quality of Cardiac Ultrasound Images, Ali Fatemi, NTNU (Read Fatemi’s blog on the topic)
    • Ultrasound and Multimodal Image-Guided Interventions, Tormod Selbekk, SINTEF
    • VScan in Stroke Diagnosis and Follow-Up, Lars Mølgaard Saxhaug, NTNU/Levanger Community Hospital.
    • The Dynamic Range of Adaptive Beamformers, Andreas Austeng, UiO
  • Medistim (Erik Swensen, Vice President R&D)
  • Inphase Solutions (Svein-Erik Måsøy, CEO)
  • US cardiology in a non-expert setting (Nord-Trøndelag, HUNT) (Professor Håvard Dalen, St. Olavs Hospital and NTNU)
  • Non linearity in underwater acoustics, and other things (Postdoc Fabrice Prieur, UiO)
  • Ultrasound blood flow imaging – state of the art and future perspectives (Professor Lasse Løvstakken, NTNU)
  • Closing remarks (Eva Nilssen, CIUS Board Director and Programme Manager GE Healthcare, and Asta Håberg, NTNU)

Leave a Comment

Filed under NTNUmedicine, Research

How to outsmart a prostate cancer cell

Siver MoestueBlogger: Siver Moestue, Associate Professor
MR Cancer Group, Department of circulation and medical imaging, NTNU

 

 

Cancer cells are notoriously difficult to deal with – partly because they have the ability to dodge the bullets we aim at them. They are inherently resistant to a lot of hostile conditions and therapies, but they can also activate compensatory mechanisms that rescue them when they are exposed to anticancer drugs. We have therefore tried to find a way to responsibly kill cancer cells (killing cancer cells without harming the normal cells in the body, that is) by identifying the crucial compensation mechanisms, and then applying a second drug that strikes the cancer cells where it hurts the most.

Essentially all the work that is performed inside our cells is carried out by proteins. Not all proteins work at the same time – most of them are responsive to cues from their surroundings that tell them when to work and when to take a break. One such cue is OGlcNacylation. Sounds difficult, but basically the cells put tiny “flags” consisting of amino sugars on proteins, thereby giving them new work orders (Figure 1).

Illustration of O-GlcNac Transferase (OGT)

Figure 1 Proteins can be activated, deactivated or otherwise change function when they are labelled with the amino sugar N-acetylglucosamine on specific amino acid residues. This process is called O-GlcNacylation, and may play an important role in cancer.

In cancer, it has been seen that an enzyme responsible for putting these amino sugar flags on proteins (OGT) is frequently over-activated. In a collaboration with Prof. Ian Mills (Norwegian Centre for Molecular Medicine) and Suzanne Walker (Harvard Medical School), we wanted to find out if a novel drug targeting OGT could be used to kill prostate cancer cells. To cut a long story short, they could – but only to a certain extent. The cells found a way to survive and continue to divide, just a little slower than before. To understand how the cancer cells escaped death, we took a deep dive into their metabolism using magnetic resonance spectroscopy.

Interestingly, we found that OGT inhibition made the cells reprogram metabolism. They stopped consuming glucose, instead turning to the common amino acid alanine as a new source of energy. Since OGlcNacylation is a process that normally allows cells to respond to starvation or altered supply of nutrients, this sort of makes sense. It also raised the question “What if we block the metabolism of the cells so they cannot use alanine anymore?”. Luckily, the well-known drug cycloserine (used to treat tuberculosis), does just that – by blocking the alanine-converting enzyme GPT2.

When we treated the prostate cancer cells with both the OGT inhibitor and cycloserine, the prostate cancer cells activated a self-destruct mechanism and died. Luckily, normal prostate cells tolerated the treatment very well.

MR spectrum of cells treated with an OGT inhibitor.

Figure 2 Left: MR spectrum showing how cells treated with an OGT inhibitor (black line) have low levels of glutamate and are virtually depleted of alanine. Right: Diagram demonstrating how LNCaP prostate cancer cells treated with a combination of an OGT inhibitor + cycloserine (blue bar) are far less viable than untreated control cells or cells treated with each of the drugs alone (grey bars).

What did we learn from all this? First, we demonstrated an important principle: Cancer cells may display metabolic ”soft spots” leaving them in a vulnerable position once they are under attack from anticancer drugs. Finding these – and attacking them with a second drug – could be a way of improving cancer therapy in the future. Second, we proved that it is possible to learn an old dog new tricks: cycloserine was developed to make it hard for tuberculosis bacteria to make their cell wall. However, as a side effect it also blocks the ability of mammalian cells to use alanine as an energy source. This does not seem to be a problem for normal cells, because they don´t depend on this mechanism at all. But under given conditions (such as when they are under attack from drugs blocking OGT), prostate cancer cells are addicted to it – and we can take advantage of that when we try to kill them.

The project was carried out with financial support from the Norwegian Cancer Society and the Research Council of Norway.

Leave a Comment

Filed under Cancer, NTNUmedicine

Improving quality of cardiac ultrasound images

Ali FatemiBlogger: Ali Fatemi, PhD Candidate
Centre for Innovative Ultrasound Solutions (CIUS), Department of circulation and medical imaging

 

 

Cardiovascular diseases (CVDs) are the number-one cause of death globally. An estimated 17.5 million people died from CVDs in 2012, 31% of all global deaths. One important factor in preventing cardiovascular disease, is early diagnosis using technologies such as ultrasound echocardiography. In this project, we study the cause of certain defects in the current echocardiograms and will try to propose new processing methods to improve the image qualities.

The quality of cardiac ultrasound images (echocardiograms) has increased significantly in the last 20 years, making it possible to correctly diagnose the occurrence of CVDs in about 80% of patients. In the remaining 20% certain physical factors hinder a correct visualization of the heart and the assessment of its function.

One of the artefacts which is seen in the echocardiograms taken from some patients, is what we refer to as “haze” artefact. In the images with this artefact a haze-like noise can be seen over the heart. This haze-like noise normally disappears when imaging deeper than 10 cm into the body in the studied cases (see the hazy echocardiogram in the figure below). In the following figure a “non-hazy” echocardiogram is shown together with a “hazy” one.

Ultrasound images

Left: a ”clear” ultrasound image of heart. Right: a ”hazy” ultrasound image of heart

Echocardiography produces real-time images of the heart, by sending ultrasonic pulses (sound waves with higher frequency than audible frequency range) in between the ribs and down into the body. Ultrasonic pulses are then reflected back to the transducer (the transmitter and receiver of the ultrasonic pulses), which can be detected and transformed into an image. However that is not the only path that the signal can take. Sometimes the signal can be partially blocked by the ribs impacting the quality of the result images. Therefore, as a potential cause of the haze artefact, we investigate the geometry of rib bones and its effect on the received ultrasound signal from the heart.

To study this effect, we carried out an experiment out of the body, where we imaged an artificial ventricle in a water tank. A section of a pork ribcage was placed on top of it to simulate the ribs effect in human body (see figure below). We imaged the ventricle through the ribs with an M5Sc transducer and E95 GE scanner. We repeated the imaging after placing the tip of a metal needle under water about 10 cm away from the transducer. Figure below shows the setup with and without the needle and the corresponding ultrasound images. We observe that the needle tip is displayed in the ultrasound image at a depth of around 11 cm (see the lower right pane in the figure below). However the needle is not expected to be visible in the image since it is placed out of the transducer field of view or “imaging plane” (a cross section of the object which is being imaged).

Ultrasound images and pork ribs with artificial ventricle

Images of the setup and corresponding ultrasound images with and without the needle. Upper left pane: image of the setup without the needle. Lower left pane: ultrasound image without the needle. Upper right pane: image of the setup with the needle. Lower right pane: ultrasound image with the needle.

This experiment shows that if the ultrasound beam is partially blocked by the ribs, then part of the energy is reflected to unwanted directions. This deflected energy can then be reflected once more by the scatterers that are present in these directions (the needle tip in our experiment) and travels back to the transducer. Therefore, the scatterers out of the imaging plane can be observed in the ultrasound image as noise. The result of this experiment can be expanded to the haze artefact in the echocardiograms with the hypothesis being:

In some patients, with a specific shape and angle of the ribs, and depending on the heart position relative to the ribs, there is no way for all of the ultrasound beam to go through the ribs before hitting the desired cross section of the heart. This leads to the beam being partially reflected and any scattering tissue out of the imaging plane is then rendered as haze noise.

At this stage, we are collecting some live data from volunteers to check the haze level in their echocardiograms. At the same time, we record some data of the shape and distance of their ribs and compare the haze level with this information.

Leave a Comment

Filed under Cardiovascular, NTNUmedicine, Other, Research

Can a psoriasis drug be used to treat breast cancer? Targeting the link between inflammation and cancer

Hanna Maja TunsetEugene KimBloggers: Hanna Maja Tunset, PhD candidate, Eugene Kim, PostDoc,
MR Cancer group, Department of circulation and medical imaging

 

 

October is nearly over. The good news is that Christmas season is just around the corner. The bad news? This is the final post from the MR Cancer group in our blog series for breast cancer awareness month! If you missed the first two blogs, you can check them out here: A new cure for breast cancer? and Could breast cancer metabolism reveal new therapeutic targets?

Breast cancer is not just one disease, and different breast cancers need different treatment. Targeted treatment according to the type of tumor has increased breast cancer survival for a lot of patients.  However, around 15 % of breast cancer patient have what we call triple negative breast cancer (TNBC), which does not respond to currently available targeted therapies. This subtype also tends to be highly aggressive, develop at a younger age, and have poorer prognosis compared to other types. Going against the overall trend in breast cancer, survival rates for TNBC have not increased in the past few decades. So, new targeted therapies for TNBC are in high demand.

One way of finding a good therapeutic target is to look for something that is unique to that particular disease. We have previously identified that the inflammatory enzyme cytosolic phospholipase A2, or cPLA2, is overly active in TNBC as compared to other breast cancers. We wanted to see if inhibiting cPLA2 could be an effective treatment.  So we teamed up with Berit Johansen, a professor at the NTNU Department of Biology and CSO of Avexxin AS, a Trondheim-based start-up company developing a line of cPLA2 inhibitors intended to treat inflammatory diseases like psoriasis and rheumatoid arthritis.

We tested one of their drugs, AVX235, in a mouse model of TNBC, and the results look promising. Tumors in mice treated with the drug only reached 1/3rd of the size of untreated control tumors after 19 days of treatment.

But how does AVX235, an anti-inflammatory drug, inhibit tumor growth?

Targeting the link between inflammation, blood vessels, and cancer

Cytosolic phospholipase A2 is highly involved in both acute and chronic inflammation in the body. In 1863, Rudolf Virchow, the father of cellular pathology, theorized that cancer was caused by chronic inflammation. Over the years, research has revealed close links between inflammation and cancer. American pathologist Harold Dvorak  went as far as to describe tumors as “wounds that do not heal”. A major component of inflammation and wound healing is angiogenesis –  the growth of new blood vessels. Angiogenesis is a hallmark of cancer and is observed in most solid tumors. As a tumor grows, it produces blood vessels that deliver the oxygen and nutrients necessary to sustain it.

Our study suggests that cPLA2 plays an important role in angiogenesis in TNBC. We found that AVX235 reduced the amount and size of blood vessels in the tumors. High-resolution CT images showed that large portions of tumors treated with AVX235 did not have a blood supply.

 

CT images of breast cancer tumours

CT-based images of representative tumors from control (Ctrl) and treated (Tx) groups, color-coded for vessel caliber (VC), i.e. vessel diameter – the more yellow or red, the larger the vessel. Note the lack of vessels in large areas of the treated tumor (arrows).

We also examined tumor tissue under the microscope, after staining for certain factors that could reveal if blood vessel cells were dividing. Treated tumors had fewer actively growing blood vessels. This indicates that blocking cPLA2 activity hindered the cancer’s ability to produce new blood vessels, resulting in tumors that were under-fed and unable to grow as they normally would.

Next steps towards improving treatment of TNBC

We are still in the early phases, but our initial results show that inhibition of cPLA2 may be a strategy for targeted therapy of TNBC. Continuing our collaboration with Avexxin, we are currently trying to find out more about how this may work. By using breast cancer cells grown in a flask as a model system, we can detect responses on a cellular level, like alterations of metabolism, how fast the cells grow, and their ability to invade new tissues.

Over the past decade, there has been an increasing interest in cPLA2 as an important player in the progression of various cancers, including breast cancer. We hope our research in this field will contribute towards providing a much-needed targeted therapy for triple negative breast cancer patients.

The results from this study was published in BMC Cancer.

This work was funded by the liaison committee between the Central Norway Regional Health Authority and the Norwegian University of Science and Technology (NTNU), the Norwegian Cancer Society, the Research Council of Norway, and Avexxin AS.

Group photo. Poto: Kari Williamson

From the back (left to righ): Astrid Jullumstrø Feuerherm, Siver Moestue, Jana Kim, Eugene Kim, Berit Johansen and Hanna Maja Tunset

Leave a Comment

Filed under Cancer, NTNUmedicine, Research

A new cure for breast cancer?

Portrettbilde SiverTrygve AndreassenBloggers: Trygve AndreassenSenior engineer, and Siver Moestue, Associate professor,
The MR Cancer Group, Department of circulation and medical imaging

 

 

Scientists all over the world are strenuously pursuing new ways of killing cancer cells. They look for so called “drug targets” – proteins the cancer cells need for rapid and uncontrolled proliferation. In collaboration with Karolinska Institutet in Sweden, we have discovered such a protein called CHPT1. Based on this discovery we think it may be possible to develop new drugs for treating breast cancer.

A needle in a haystack

Before we can develop a new cancer drug, we must have some idea about what the drug should do. We have to identify a “drug target” – a protein the drug must recognize, bind to and alter the function of. It is not as simple as it might sound – we have about 20,000 different protein coding genes in our DNA, and it has been estimated that they can produce up to 100,000 different proteins (Savage, Nature 2015). These proteins communicate with each other in various ways, which means that we are trying to find a needle in a pretty big haystack.

Cancer drugs are often designed to block processes that are important for cell division, or the copying of DNA that happens prior to every cell division. In our research group, we are interested in the metabolism of cancer cells (in order to grow and divide fast, the cancer cells will reprogram their metabolism), and therefore we have searched for possible target proteins in the biochemical pathways.

In collaboration with Karolinska Institutet in Sweden, we started out with some known characteristics of breast cancer cells: They often grow faster in the presence of oestrogen; and they have an abnormally high turnover of the molecule choline. In order to study the choline turnover we apply a technique called MR-spectroscopy.

Main suspect: CHPT1

First we identified about 18,000 oestrogen binding domains in DNA, and found that these domains control the expression of about 2500 genes. Next we found how many of these genes that could be involved in choline turnover – hereby reducing the number of candidate genes to 19. By interpreting MR-spectra of cancer cells grown with and without oestrogen, we found which metabolic changes that could be derived from oestrogen stimulation. This allowed us to further reduce the number of proteins – and eventually we suspected the protein CHPT1 of being heavily involved in transferring the stimulating effect of oestrogen to the metabolic machinery of cancer cells.

To make sure that our findings are not only valid for cancer cells grown in the lab, we investigated tumour tissue from 70 breast cancer patients. Here we found higher expression of CHPT1 in tumour tissue compared to normal breast tissue. Even more interesting, we could see that tumours classified as oestrogen sensitive had significantly higher CHPT1 expression than the other tumours. This implies that oestrogen actually activates CHPT1 in breast cancer patients.

The next step in proving that CHPT1 is a relevant drug target was to show what happens if we switch off this gene. In the laboratory we have molecular tools which allow us to stop the production of the CHPT1-protein in cancer cells, and we found that cancer cells grew much slower when CHPT1 was switched off (Figure 1).

Figur 1: Brystkreftceller i mikroskop.

Figure 1: The two pictures to the left show to different types of breast cancer, seen in a microscope when growing freely in a dish. In the pictures to the right (marked siCHPT1) we see the same cells, but here we have “switched off” CHPT1. There are clearly fewer cells, which indicates that the cells need CHPT1 to grow and divide.

Killing cells in a dish at the lab is fairly easy, so the next step was to see if we could influence tumour growth in a living organism. Our choice of organism was zebrafish (they are quite transparent which enables us to observe the cancer cells directly). By switching off CHPT1 we could see that both tumour growth, as well as the cancer cells’ ability to spread to other tissue and organs, was reduced (Figure 2).

Sebrafisklarve med svulster.

Figure 2: Above we see a zebrafish larva with implanted oestrogen sensitive MCF-7 cancer cells. They have developed a tumour at the injections site (red colour), and daughter tumours (metastases) have formed along the spine (marked with arrows (6). Below we see a zebrafish larva injected with the same type of cancer cells, but with CHPT1 switched off (siCHPT1). Here, there is no big tumour at the injection site, and there are clearly fewer daughter tumours along the spine (marked with arrows (3)).

All in all, we have presented several indicators suggesting that CHPT1 may be an important drug target for the treatment of oestrogen sensitive breast cancer. But there are still many things we haven’t found out yet: Is it possible to design drugs that block CHPT1? What are the side effects? Are they superior to existing drugs?

We have published our findings and hope that someone will take up the gauntlet and continue working on our ideas. And hopefully be able to develop a new drug based on our basic research.

The project has been partly funded by the Norwegian Cancer Society and the Research Council of Norway.

Leave a Comment

Filed under Cancer, NTNUmedicine, Research