Tag Archives: ISB

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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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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How water motion can tell us about cancer treatment effectiveness

Jana CebullaBlogger: Jana CebullaPostDoc
MR Cancer Group, Department of Circulation and Medical Imaging

 

 

 

Just as every human being is a unique individual, every cancer has its own characteristics, and this is increasingly being recognised in cancer treatment. Targeted therapies are being developed that attack cancers on the molecular level and treatment strategies are tailor-made for each patient.

But how do we know that a treatment actually works?

Typically, treatment response is measured as a change in tumour size using anatomical MRI or CT images, or tumour markers found in body fluids. However, these changes usually occur quite late in the course of the treatment. This is especially true of new, targeted therapies that do not directly kill cancer cells, but cause more subtle structural changes in the tumour tissue. These new therapies aim for a better treatment effect with less side-effects, but because the changes are so subtle, it also means it could be more difficult to see if a treatment is effective or not. Continue reading

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Furry and fit: get moving this Movember!

Debbie Hill og Leslie WoodBloggers: Researcher Debbie Hill og PhD Candidate Leslie Euceda Wood
MR Cancer group, Department for ciruclation and medical imaging

 

 

 

It’s that time of year again! And this year, the Movember Foundation is challenging YOU to move every day this month to tackle physical inactivity. In keeping with the Movember spirit, the MR Cancer group (and friends!) donned their best training gear, and ventured out into the crisp breeze of a lovely November morning. Not only to raise a few smiles, but also to raise awareness for men’s health and prostate cancer.

MR Cancer-gruppen i treningstøy og barter.

According to the Movember Foundation a lack of physical activity is the fourth leading risk factor for global mortality, causing 3.2 million deaths worldwide per year. There is a push to combat physical inactivity by:

  1. Getting people moving (check out the MOVE campaign)
  2. Raising awareness on the dangers of physical inactivity & benefits of activity for both physical and mental health
  3. Finding new ways to encourage physical activity
  4. Investing in projects that increase understanding of what motivates men to move. Continue reading

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Planning the direction for CIUS

CIUS-people

Photo: Kristina Jones/NTNU

45 people from both academia and the industry were present at the first meeting discussing the direction for half the different work packages at NTNUs new centre CIUS, a Centre for Innovative Ultrasound Solutions for health care, maritime, and oil & gas.

– At this point, before we can start the work, it is important for us to point out the further direction for the research in some of the work packages at the centre. Work packages 1-4, in ultrasound knowledge and technology, and no 7, in clinical feasibility, are the fundament onto which all the other work packages will build, Asta Håberg, the head of CIUS, says.

CIUS is a Norwegian Research Council appointed centre for research-based innovation (SFI) and is located at Department of Medical Imaging and Circulation at Norwegian University of Science and Technology (NTNU) in Trondheim.

– CIUS will deliver novel ultrasound technology solutions for the benefit of the involved partners, new diagnostic tools for the benefit of patients and the Norwegian healthcare system, important knowledge disseminated in highly recognized scientific journals, and skilled personnel to further exploit the future potential of ultrasound imaging in Norwegian industries, healthcare and academia, Håberg says.

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Shutting off blood supply to an extremity to protect the heart

på operasjonssal

Foto: Geir Mogen

In a study just published in the International Journal of Cardiology, researchers from CERG and the Department of Cardiothoracic Surgery at the St. Olav’s Hospital have shown that shutting off the blood supply to an arm or leg before cardiac surgery protects the heart during the operation.

We wanted to see how the muscle of the left chamber of the heart was affected by a technique, called RIPC (remote ischemic preconditioning), during cardiac surgery. RIPC works by shutting off the blood supply to an arm or a leg before heart surgery. The goal is to reduce risk during cardiac surgery in the future.

Read more at CERG’s blog

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To treat or not to treat? The role of PET/MRI in prostate cancer

Mattijs ElschotBlog by: Mattijs Elschot
Postdoctoral Fellow at MR Cancer Group

Some prostate cancer patients need radical surgery to survive, whereas others can do without any form of treatment. The urologist determines to which group a patient belongs. Researchers at NTNU/St. Olavs Hospital investigate whether a PET/MRI scan can help making the correct decision.

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Early markers of a potentially dangerous type of prostate cancer

Morten Beck RyeBloggers: May-Britt Tessemansattebilde.may-britt.tessem and Morten Beck Rye

As we speak there are no accurate methods to diagnose potentially dangerous prostate cancer in an early stage of cancer.

From a pathologist’s point of view, aggressive cancers look totally similar to harmless subtypes in the beginning of development. As a consequence, the patients will be at high risk of overtreatment in the majority of cases where prostate cancer is detected. We urgently need new tools and markers to sort out the potentially dangerous types of prostate cancer from the non-dangerous in early disease. Most importantly, this will save the patients from reduced quality of life due to unnecessary surgical interventions, and also be economically beneficial for society.

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New method for characterizing brain tumors

Blogger: Morteza EsmaeiliMortezaE
Postdoctoral Fellow at MR Cancer Group, NTNU

 

A new non-invasive method can identify a special mutation in a type of brain tumor called gliomas. This unique test can assist in research towards new treatments that target cancer cells in glioma patients carrying this mutation. The new method is developed by my colleagues and me at MR Cancer Group at NTNU and researchers at the Departments of Radiology and Pathology of Radboud University Medical Center in Nijmegen. We believe it is an important step towards improved tools for the diagnosis and treatment evaluation of brain tumor patients.

Gliomas are common subtypes of primary brain tumors that originate from glial cells in the brain. There are different grades of gliomas, indicating their degree of aggressiveness; however, they are most often classified as “low-grade” or “high-grade” gliomas. Glioblastomas are the most aggressive type of gliomas. Various types of gliomas have been identified, and they have different clinical behavior and response to treatment. This means there is an urgent need for more accurate and precise diagnosis, prognosis, and therapy monitoring tools.

MR-bilde av en hjerne

Gliomas are common subtypes of primary brain tumors that originate from glial cells in the brain. A new non-invasive method can identify a special mutation in gliomas. (Photo: Geir Mogen/NTNU)

Conventional anatomical imaging methods, such as magnetic resonance imaging (MRI) (Figure 1), provide limited information on tumor characterization and prognosis. Advances in personalized patient management and new drug treatments for brain tumors have generated increasing demand for reproducible, non-invasive, quantitative imaging biomarkers.

Recent developments have concentrated on the role of physiological and metabolic MRI, such as magnetic resonance spectroscopy (MRS, see an example in Figure 2), and other molecular imaging methods in understanding the metabolic processes associated with tumor growth and progression. These studies have indicated that cancer cell metabolism, contrary to the metabolism in normal cells, is modulated and reprogrammed to facilitate additional/excessive demands for biomass generation and rapid cellular growth and proliferation. This particular characteristic of cancer cells can be targeted as a “weak point” to kill these cells.

This particular characteristic of cancer cells can be targeted as a “weak point” to kill these cells.

Furthermore, the utility of various techniques in distinguishing between aggressive and benign tumors, tumor grading, and treatment response evaluation and monitoring are also of interest.

Conventional MR imaging of glioblastoma

Figure 1: Conventional MR imaging of glioblastoma. Tumor regions can be identified by different MR contrasts; For example, (A) T1-weighted pre-contrast exhibit a low-intensity lesion in the left frontal lobe region (yellow arrow), (B) post-contrast MR image demonstrates a focus of enhancement in that area, (C) and T2-weighted MR image shows increased-intensity at the same region. These MR techniques enable non-invasive imaging and diagnosis of tumor lesions in the brain. Illustration is adapted from Ahmed R. et al. Cancer Manag Res, 2014 (with permission).

During our study, we uncovered a new imaging biomarker to identify glioma subtypes with different prognosis and therefore this biomarker may be used for a better clinical management, avoiding extra cost for patients and communities. More specifically the biomarker concerns metabolite levels associated with a mutated IDH gene found in more than 70% of the brain tumors classified as low-grade gliomas and secondary gliomas. Glioma patients with this mutation actually have a better prognosis.

In particular, with our MRS technique we observe the indirect effect of the mutation in the IDH1 gene on the level of some phospholipid metabolites, which can be considered a molecular “finger print” for this mutation. These metabolites are major components of phospholipid metabolism in the synthesis of cancer cell membranes.

MR spectroscopy provides information additional to conventional MRI

Figure 2: MR spectroscopy provides information additional to conventional MRI. T2-weighted MR images of a mouse brain with glioma tumor (top, A) and a healthy mouse brain (bottom, B), and corresponding MRS data from area of interest (blue circles, C and D). MRS detects signals for different metabolites in normal brain and tumor tissue. In particular phospholipid metabolites are of interest to characterize brain tumors. (from left to right); PE, phosphoethanolamine; PC, phosphocholine; GPE, glycerophosphoethanolamine; GPC, glycerophosphocholine. Adapted from Esmaeili M. et al. Cancer Res. 2014 (with permission).

To be a bit technical: IDH1 acts in an energy-generating pathway known as the citric-acid cycle, and the IDH1 mutations associated with cancer causes a metabolite called 2-hydroxyglutarate to accumulate. IDH1 catalyzes the conversion of isocitrate into α-ketoglutarate, a reaction that takes place in energy-generating metabolic pathways. Most remarkable is that the mutated IDH1 enzyme has acquired the capacity to produce 2-hydroxyglutarate, which can accumulate in high concentrations in gliomas with the mutation. 2-hydroxyglutarate is commonly called an oncometabolite. Our finding shows that the mutation also alters lipogenesis in brain cancer cells. Phospholipid metabolism is a major network supporting cellular lipogenesis and cell membrane turnover.

The discovery of the IDH1 mutation has generated such intense interest that pharmaceutical companies are keen to find drugs that target mutant IDH1 gliomas

The discovery of the IDH1 mutation has generated such intense interest that pharmaceutical companies are keen to find drugs that target mutant IDH1 gliomas, with some companies focusing exclusively on targeting cancer metabolism. The findings of this study and those published recently on IDH related metabolism could be used in the development of drugs for cancers with these mutations. In addition, these findings enable the detection through non-invasive imaging of the direct metabolic consequence of a genetic mutation in a cancer cell. This offers a potential new tool in the management of brain tumor patients.

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