Category Archives: Cardiovascular

Coronary heart disease, diseases of the vasculature and circulation including the lymphatic system, and normal development and function of the cardiovascular system.

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.

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Avoiding unnecessary coronary angiograms

Bjørn Olav HaugenBlogger: Bjørn Olav Haugen, Professor,
Centre for Innovative Ultrasound Solutions, Department of circulation and medical imaging

Angina is chest pain that occurs when the blood supply to the muscles of the heart is restricted. It usually happens because the coronary arteries supplying the heart become hardened and narrowed.

A coronary angiogram (CA) is an X-ray test done to find out if the coronary arteries are blocked or narrowed. If medication does not reduce the symptoms, it is usually recommended to do a coronary angiogram to help the cardiologist to see if you need treatment such as angioplasty with implantation of a stent (PCI), or coronary artery bypass surgery (CABG). Continue reading

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Interpreting ultrasound images with neural networks

Erik SmistadBlogger: Erik Smistad, PostDoc at Centre for Innovative Ultrasound Solutions (CIUS)




Neural networks have recently achieved incredible results for recognising objects such as cats, coffee cups, cars and plants in photographs. These methods are already used by companies like Facebook and Google to identify faces, recognize voice commands and even enable self-driving cars. At the Centre for Innovative Ultrasound Solutions (CIUS), we aim to use these methods to interpret ultrasound images. Ultrasound images can be challenging for humans to interpret and requires a lot of training. We believe neural networks can be used to make it easier to use ultrasound, interpret the images, extract quantitative information, and even help diagnose the patient. This may ultimately improve patient care, reduce complications and lower costs.

Low-level image representations learned by an artificial neural network.

Low-level image representations learnt by an artificial neural network.

Artificial neural networks are simplified versions of the neural networks in the human brain. These networks are able to learn directly from a set of images. By showing a neural network many images of a cat, the network is able to learn how to recognise a cat.

Neural networks are organized into several processing layers which learn different levels of image representation, from low-level representations such as edges, to high-level representations such as the shape of a cat. The image representations are used to distinguish one object from another. Over the years the trend has been to increase the number of layers and thus referred to as deep neural networks and deep learning.

Experiments have shown that deeper neural networks can learn to do even more advanced tasks. Recently, such a deep neural network beat the world champion in the game Go – a game more complex than chess.

One of the challenges with these methods is to collect enough data. Many images are required for the neural network to learn the anatomical variation present in the human population and how the objects appear in ultrasound images. Also, the data must be labelled by experts, which can be a time-consuming process.

In a recent study, we created a neural network able to detect and highlight blood vessels in ultrasound images as shown in the figure below. This was done by training a neural network with over 10,000 examples of images with and without blood vessels. When the neural network is presented with fresh images it is able to recognise blood vessels – it has learnt what a blood vessels looks like in an ultrasound image.

Blood vessels automatically located and highlighted by a neural network.

Blood vessels automatically located and highlighted by a neural network.

Currently, we are investigating how these neural networks can locate structures such as nerves in ultrasound images, which can be difficult even for humans. The figure below shows the femoral nerve of the thigh in yellow, located automatically by an artificial neural network. Identifying these nerves is crucial when performing ultrasound-guided regional anesthesia.

The femoral nerve (yellow) and femoral artery (red).

The femoral nerve (yellow) and femoral artery (red).

Erik Smistad is a PostDoc at CIUS working on machine learning and segmentation techniques for ultrasound image understanding. You can learn more about his research on his own website: Erik Smistad.

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Cyclodextrin, a sugar with promising potential for treatment of atherosclerosis!

Bloggers: Siril S. Bakke and Terje Espevik, researchers at CEMIRBakke-og-Espevik

Cardiovascular disease resulting from atherosclerosis is one of the most common causes of death worldwide. Inflammation plays a crucial role in atherosclerosis and cholesterol crystals are candidate triggers early in the development of the disease. Continue reading

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Brain changes in U-2 pilots due to altitude exposure – NATO high altitude research at NTNU

Andreas MøllerløkkenMarianne Bjordal HavnesBloggers:
Marianne Bjordal Havnes, Post Doc
Andreas MøllerløkkenResearcher,
The Barophysiology group at the Department of circulation and medical imaging



Researchers are trying to find out why U-2 pilots operating in high altitude have  central nervous system changes in a NATO-led project involving researchers from the Barophysiology group at NTNU, researchers from the U.S. Air Force in Texas and from the Institute of Aviation Medicine in Oslo.

You have probably been in a passenger jet, and as you get ready for take-off, you register the cabin attendants going through the safety instructions, mentioning something about loss of cabin pressure and oxygen masks, but you don’t worry about it. 15 minutes later the captain announces that the airplane has reached its cruising altitude of 38,000 feet. At this altitude the barometric pressure is only 1/5 of sea level pressure.

U-2 aeroplane. Photo: Dr Stephen McGuire USAF.Inside the aircraft the pressurisation system ensures that the cabin altitude according to international regulations will never exceed 8000 feet = ¾ of sea level pressure. So while you are travelling, you are actually performing a little mountain-excursion to the same altitude as Norway’s highest mountain, Galdhøpiggen.

Now imagine that you are flying twice as high as your airliner. At an altitude of 70,000+ feet the barometric pressure is 1/25th of an atmosphere. You can see the curvature of the earth and the blackness of space above. This is where the U-2 pilots are working. If you lose the cabin pressure in this environment, an oxygen mask will be of no help. You need to wear a space suit that will instantly inflate to a pressure of 0.3 bar (corresponding to 30,000 feet) and supply you with a breathing gas of 100% oxygen.

The U-2 planes have been operating since the 50s and are still in active duty. In fact, U-2 pilots have actually been flying more the last 10 years as other high-altitude reconnaissance airplanes have retired. This has resulted in an increased number of neurologic decompression sickness episodes.

A US Air Force research team has published findings of what are called white matter hyperintensities in the brain on magnetic resonance imaging (MRI) of U-2 pilots (McGuire et al., 2013) . Recently they have discovered similar findings in U.S. Air Force altitude chamber instructors (McGuire et al., 2014). This group works inside hypobaric chambers, training aircrew including U-2 pilots, in the effect of loss of cabin pressure and lack of oxygen. The altitude exposure in hypobaric chamber training is usually much shorter and less severe than in U-2 operations. None of the other U.S. Air Force control groups they have tested so far, including Air Force doctors, have had similar changes.

The U.S. Air Force research team visited the Institute for Aviation Medicine, Oslo, Norway, and wanted to meet Norwegian research groups that might contribute to understanding the pathophysiology behind the findings. Members of the NTNU Barophysiology group were invited based on their merits for a long time commitment to research on man in extreme environments.

U-2 aeroplane. Photo: Dr Stephen McGuire USAF.U-2 aeroplane. Photo: Dr Stephen McGuire USAF.

Most of the work of the NTNU Barophysiology group has been related to the activity of diving and the adverse effects of working under water. Presently, the research is funded by the Norwegian Research Council through the Petromaks programme.

From left: Berit Holte Munkeby, MD, PhD, Norwegian Armed Forces, Dr Paul Sherman, USAF, Andreas Møllerløkken, PhD NTNU, Marianne Bjordal Havnes, PhD, NTNU, Dr Stephen McGuire USAF.

From left: Berit Holte Munkeby, MD, PhD, Norwegian Armed Forces, Dr Paul Sherman, USAF, Andreas Møllerløkken, PhD NTNU, Marianne Bjordal Havnes, PhD, NTNU, Dr Stephen McGuire USAF.

One of the technologies we are using in assessing possible stress after a dive is ultrasound detection of gas bubbles found in blood veins. These bubbles will form in nearly all diving activity, and it is recognised that the risk of decompression sickness increases with increasing amounts of bubbles.

Our way of observing vascular gas bubbles after diving has become a recognised method for evaluating procedures.  It has also been shown both in animals and humans that the bubbles themselves influence the endothelium lining all blood vessels. When going to high altitudes, the pressure changes are opposite of diving. But there are many similarities as well, and the formation of bubbles is thought to be involved in the formation of the white matter hyperintensities.

After the meeting in Oslo, the researchers from NTNU did some preliminary investigations, and were invited to Lackland Air Force Base in Texas where the main investigation is taking place. The results from the tests at NTNU have already been presented at a NATO high altitude exposure meeting this summer in Paris, and has gained a lot of attention within NATO. Together with the Institute of Aviation Medicine in Oslo, the researchers from the Department of circulation and medical imaging are eager to continue the investigations.

U-2 aeroplane. Photo: Dr Stephen McGuire USAF.

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Unveiling connections between preeclampsia and cardiovascular disease

Women with preeclampsia have up to eight times higher risk of later developing cardiovascular disease. CEMIR’s research group on Inflammation and Genetics in Pregnancy studies how the development of preeclampsia and cardiovascular disease are connected.


Liv Cecilie Vestrheim Thomsen (left) and Lobke Gierman.

The group has recently unveiled inflammatory mechanisms in the placenta and identified an important role for fetal trophoblasts. They have also identified a gene variant that is protective for both preeclampsia and cardiovascular disease.

This research was recently presented at the International Society for the Study of Hypertension in Pregnancy (ISSHP), a conference about research and treatment of hypersensitive diseases during pregnancy, primarily preeclampsia and gestational hypertension.

Researcher Liv Cecilie Vestrheim Thomsen received the prize for best poster and Post.doc. Lobke Gierman received third place in the category best oral presentation.

Article in Placenta:   Toll-like receptor profiling of seven trophoblast cell lines warrants caution for translation to primary trophoblasts


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Deep research: keeping fit on the bottom of the North Sea

FatimaKiboub_Foto_NTNU_profilBlogger: Fatima Zohra Kiboub
Industrial PhD Candidate, Lead QHSE Engineer, Technip




Deep saturation divers

The working environment, health and safety of an offshore diver has significantly improved since the 1990s and saturation diving is today among the safest offshore occupations.

Crucial to our gas and oil industry, the offshore divers perform their work on the ocean floor of the Norwegian continental shelf. Not unlike the astronauts, these divers – the aquanauts – encounter environments that challenge the body’s capacity for adaptations. We look at how their bodies respond and what makes them fit and healthy.

Saturation diving is a very challenging job and the divers have to be extremely fit and healthy. The divers live at an elevated atmospheric pressure inside a pressure chamber, which is equal to the pressure at the water depth they will work at. They breathe a mixture of helium and oxygen called Heliox, which makes their voices sound like Mickey Mouse!

When working at depths of 50-180 metres, it is dark and the seawater is very cold – around 4-8°C. The divers are therefore dressed in neoprene wet suits where heated seawater is pumped through to keep them warm. It is like floating in a heated spa pool. They wear a helmet, wellington boots and rubber gloves, which could be mistaken for dishwashing gloves.

Many research projects have been conducted with recreational divers and also offshore air divers, but there are not many research projects on offshore saturation diving – and even less research done with real-life saturation divers in their own working environment.

New science indicates that the high-pressure working environment makes the body initiate an inflammatory reaction, with possible release of stress biomarkers into the blood stream. This is of course closely linked to the function of the vascular system. This gave us the idea to not only study the effects of diving on the vascular system and how the body adapts to such conditions; but also how to improve the long-term health monitoring.


The main part of my PhD project is to see if the intake of antioxidants in the form of vitamin C and E will reduce the stress biomarkers found in the blood of saturation divers. The participating offshore divers will be given vitamins every day whilst living in the pressure chamber and blood samples will be taken before entering and upon leaving the chamber. The results will be compared with a control group not taking vitamins.

After obtaining the approval of my employer, Technip – which performs subsea construction work for the oil & gas industry; and after securing funding from the Norwegian Research Council and the necessary ethical authorisation to perform research on humans, I could start my PhD research at the Medical Faculty at NTNU doing data- and samples collection during the 2015 offshore season.

Testing ultrasound equipment

Here you can see my manager Morten in the improvised ultrasound testing room and Andreas in the back making sure that the FMD protocol was followed properly.

Before going offshore, one of my PhD supervisors, Andreas Møllerløkken, provided training on how to use an ultrasound machine to run a test called Flow Mediated Dilation (FMD). This test measurers how much a large artery of the arm can expand after the blood flow has been reduced for 5 minutes using an inflated blood pressure cuff. FMD is a much used indicator of vascular health. We used my office colleagues as guinea pigs in order to practice before going offshore.

We also obtained the centrifuges and cooling transportation boxes required for our mission, and on 2nd June, it was time for the fun part of the project to begin!

My main supervisor, Ingrid Eftedal, and I took all the equipment to the hospital on board the Skandi Arctic Dive Support Vessel. We received a warm welcome by all the crew, and by the end of the first day, we had already tested two divers.

The divers had joined the vessel by 6th June. They all went through the medical pre-dive check and some were also due to have their annual direct oxygen uptake (VO2max) test.

Initially, eight divers agreed to participate in the project, and we took their blood samples and ran FMD tests. It was a great relief to actually get started.

Medical tests onboard

As the blood samples also will be used in two other research projects run by the barophysiology group at NTNU, we are taking four test tubes of blood from the divers and 3 from the non-divers to study different paramenters. This has earnt me the nichname ‘The Vampire’, although it is the nurse taking the actual samples!

We centrifuge the tubes with blood and anticoagulant to separate the plasma into tubes for freezing and later analysis at the NTNU laboratory.

We also measure percentage of red blood cells onboard, and record the results in our log sheet.

In addition to ‘normal’ health check such as taking the blood pressure, we ran FMD test using an ultrasound machine in combination with an electro cardiogram (ECG). This test shows how much the brachial artery in the arm can expand after 5 minutes of pressure in the forearm. It is a good indicator of artery elasticity reflecting vascular health.

The divers who were due to take their annual VO2max test, measuring the maximum oxygen uptake in the blood, were running on the onboard treadmill placed within the vessel’s hospital.

I have to say it is not easy to work when the ‘ground’ is moving in all directions all the time, but when the sea calmed down enough, it was safe for the divers to run on the treadmill. All our non-divers also passed the test with extremely good results – it is amasing how fit these guys are despite varying lifestyles and age groups!

In fact there is a bit of jovial competition around the VO2max tests. And the vessel has several provisions for staying active with half a basketball pitch, golf course simulator, boxing gym, table-tennis room and a darts board in addition to the two gyms.

Sports halls onboard

On 9th June there was a crew change, another four of the divers agreed to participate in the project. As one of my biggest concerns has been to get enough divers to participate and to be able to do the tests as planned, I was very pleased about this.

By the 14th June, the campaign was completed and we headed back to Stavanger. Here I did a full handover to the new nurse, who would perform the tests on the batch of divers coming out of decompression on the 15th. The day after, a new team of divers arrived, and most of them agreed to participate thanks to the efforts of our crewing office in Aberdeen.

The Skandi and its divers control room

The diving chambers control room onboard the Skandi is there to keep the divers safe inside the pressurised chambers until they are decompressed back to surface pressure again – a process that can take 2-10 days depending on the depth the divers have been working at

In July I will sign on again, and if all goes well, I will be done with all the sampling and diver testing by mid-July, just in time to spend Ramadhan in Stavanger. In the autumn I will analyse the blood samples and test results, and hopefuly we will be able to share some early results with the Skandi Arctic crew presenting the results to those that partcipated or otherwise have shown an interest in our work.

Working offshore has its challenges including seasickness and a working environment in constant motion. Although phone signals were patchy I managed to get in touch with my family in Algeria and tell them their Saharan girl was having a blast in the middle of the North Sea!

Fatima Zohra Kiboub is a Lead QHSE Engineer at Technip and is doing an industrial PhD with the barophysiology group at the Deparment of circulation and medical imaging (ISB) at NTNU.

Want to know more about life onboard the Skandi Arctic? Check out this video.

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The exercise pill, are we ready for it?

Jose Bianco MoreiraBlogger: Jose Bianco Moreria,
Post doctor at K. G. Jebsen – Senter for hjertetrening (CERG)

Every once in while we talk here about this magic medicine. What about a drug to make your muscles stronger, your heart healthier, power-up metabolism, reduce body weight, improve blood flow in your brain and manh other benefits? Isn’t it great?

Although many people would say yes, we commonly meet many that are against that idea for a number of reasons. For example, it’s well known that physical activity levels have decreased dramatically in the past 100 years in almost all countries, so it’s been thought that a drug to ”copy” exercise would be just one more reason NOT to go out for a work out. And how about elite sports? Doping is an increasing problem in the field, so another pill to enhance performance could lead to more abuse of such substances. Or perhaps more improtant: if exercising promotes so many benefits for health, would the world really need an expensive drug that does (part of) the same thing?

Read the whole blogpost at CERG’s blog here!

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Copenhagen next!

We’re off to Copenhagen! You can meet us at the Science in The City festival from tomorrow until Thursday 26. July.

This is what we are doing there:

On Saturday at 17:00 our researcher Garrett Newton Andersen will demonstrate a hand-held ultrasound machine (Vscan) on stage:



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Cardiovascular disease is associated with increased risk of rheumatoid arthritis

Blogger: Vibeke VidemVibeke Videm. Foto: Geir Mogen

Twice as many of those who got rheumatoid arthritis between the HUNT2 population-based health survey in 1995-1997 and the next survey (HUNT3) in 2006-2008, reported previous cardiovascular disease at HUNT2. They either had angina or had suffered a myocardial infarction or stroke. The data indicate that there may be a causative link.

(…) chronic inflammation in one part of the body intensifies chronic inflammatory processes in other parts

Atherosclerosis, the most common cause of cardiovascular disease, is caused by chronic inflammation in the vessel walls. Rheumatoid arthritis is due to a gradual process with increasing dysregulation of the immune system that finally leads to inflammation in the joints. The inflammation due to atherosclerosis probably intensifies the process leading to rheumatoid arthritis. The study was recently published in the scientific journal  Arthritis Research and Therapy.


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Filed under Cardiovascular, Generic Health Relevance, Inflammatory and Immune System, NTNUmedicine, Research, Stroke