MRI


MR-CT-PET Fusion
- a free, open source software revolution

The new version of OsiriX is taking diagnosotic imaging to a whole new level. The advanced opensource PACS workstation DICOM viewer for the Mac OS, is capable of combining a range of imaging modalities, such as MRI, PET, CT, ultrasound, angiographic
images and even dynamic cardiac motion and functional metabolic studies. Middle East Health reports.

There is increasing demand in diagnostic imaging for combined or hybrid imaging for complex diseases. And while PET-CT has been around for some time and hybrid PET-MR machines are very new and expensive – a new open-source software application is offering radiologists the ability to fuse PET, CT and MR images in a variety of combinations.

The creators of OsiriX, the advanced open-source PACS workstation DICOM viewer for the Mac OS, showed off their new 64-bit viewer on the new Mac Pro 8-Core workstation at the European Congress of Radiology (ECR) in Vienna, earlier this year.

The creators define OsiriX as a powerful interactive image processing and visualisation software program designed for the display and analysis of large sets of three dimensional medical images.

The new 64-bit program is specifically designed to handle new generation imaging modalities combining anatomical and metabolic images (MRI, PET, CT, ultrasound, and angiographic images). It also provides dynamic display for timevarying images such as cardiac motion or metabolic functional studies.

The key initiator behind OsiriX, Osman Ratib, Professor and Chairman of the Department of Radiology and Head of the Division of Nuclear Medicine at the University Hospital of Geneva, said: “The new 64-bit extension to the OsiriX software represents a significant performance advantage over traditional medical imaging solutions allowing users to quickly load and view very large datasets.”

OsiriX for free

OsiriX software is distributed free of charge as an open-source software under the GNU licensing scheme <www.gnu.org>. OsiriX software was developed through a collaboration between the University of California, Los Angeles and the University of Geneva. Designed by a team of radiologists it provides an intuitive and user friendly user interface tailored for physicians that are not familiar with complex image processing.

Open source
Open Source Software promotes the development and sharing of software source code. The rationale behind open source is simple: When programmers can read, redistribute and modify the source code for a piece of software, the software evolves. People improve and adapt it. And this can happen at a speed that is generally much faster than conventional software development. The rapidly growing open source community has realised that this fast evolutionary process produces better software than the traditional closed model.

Open Source offers freedom from software licensing costs. With reduced cost software upgrades, and no license expiration. The medical informatics community has welcomed Open Source Software, which fits well with its scientific model of shared, peer-reviewed knowledge in medicine.

Vendors of open-source applications can share development costs with the users’ community and focus on implementation and support services. The resulting paradigm shift is that opensource medical system vendors can become professional service providers, competing on service quality rather than on the basis of software secrets.

Dr Ratib pointed out that new tools and new ways are required to explore multidimensional data generated by modern imaging techniques.

“New software platforms need to be simple and intuitive and provide extremely fast and powerful processing capabilities allowing the users to easily navigate and explore complex anatomical and functional features of these examinations. This is the main rationale behind the development of OsiriX.”

At the ECR Dr Ratib said that matching CT with MR was relatively simple.

“The challenge comes when fusing a PET image with an MR image that was acquired at a different time, on a different scanner, and at a different orientation – which is a typical medical case.”

Using several pairs of reference points located in the area of interest, the OsiriX software correlates anatomic pointers from the CT element of the PET/CT scan (or SPECT image) with those of the MR scan. With these points established (the more pointers selected the greater the accuracy) the program allows the user to realign the CT image with the MR image in a matter of seconds consequently also combining the PET/MR information accurately.

“Once you've done that, you can use the registration tool to create a new set of images that are perfectly aligned, and which you can manipulate and play with,” Dr Ratib said. “It provides convenient and fast visualisation and navigation capabilities across a large number of multimodality images, and, of course, it is free and runs on off-the-shelf software.”

Dr Will Adair, a radiologist from the Leicester Royal Infirmary in the UK, is a regular user of OsiriX on his MacBook. He welcomed this latest development saying: “Until recently, medical imaging was accessible only to a limited number of dedicated work stations using expensive, proprietary solutions. The combined OsiriX and Mac proposition has the potential to completely change the way we work by providing easy access to affordable, commercial-level image processing solutions with exceptional 3D and 4D capabilities.”

●To find out more about OsiriX visit: www.osirixviewer.com

● View sample of Head MRI 4D rendering www.osirixviewer.com/PICTS/HeadFlyThru.mov
 

Hard-wired for hierarchy

Researchers using functional MRI have got the first glimpse of what appears to show circuitry in the human brain identified with social status. Middle East Health reports.

Human imaging studies have for the first time identified brain circuitry associated with social status, according to researchers at the US National Institute of Mental Health (NIMH). They found that different brain areas are activated when a person moves up or down in a pecking order – or simply views perceived social superiors or inferiors. Circuitry activated by important events responded to a potential change in hierarchical status as much as it did to winning money.



“Our position in social hierarchies strongly influences motivation as well as physical and mental health,” said NIMH Director Thomas R Insel, MD. “This first glimpse into how the brain processes that information advances our understanding of an important factor that can impact public health.”

Caroline Zink, PhD, Andreas Meyer-Lindenberg, MD, PhD, and colleagues of the NIMH Genes Cognition and Psychosis Program, report on their functional magnetic resonance imaging (fMRI) study in the 24 April 2008 issue of the journal Neuron. Meyer-Lindenberg is now director of Germany’s Central Institute of Mental Health.

Prior studies have shown that social status strongly predicts health. Animals chronically stressed by their hierarchical position have high rates of cardiovascular and depression / anxiety-like syndromes. A classic study of British civil servants found that the lower one ranked, the higher the odds for developing cardiovascular disease and dying early. Lower social rank likely compromises health through psychological effects, such as by limiting control over one’s life and interactions with others. However, in hierarchies that allow for more upward mobility, those at the top who stand to lose their positions can have higher risk for stressrelated illness. Yet little is known about how the human brain translates such factors into health risk.

To find out, the NIMH researchers created an artificial social hierarchy in which 72 participants played an interactive computer game for money. They were assigned a status that they were told was based on their playing skill. In fact, the game outcomes were predetermined and the other “players” simulated by computer. While their brain activity was monitored by fMRI, participants intermittently saw pictures and scores of an inferior and a superior “player” they thought were simultaneously playing in other rooms.

Although they knew the perceived players’ scores would not affect their own outcomes or reward – and were instructed to ignore them – participants' brain activity and behavior were highly influenced by their position in the implied hierarchy.

“The processing of hierarchical information seems to be hard-wired, occurring even outside of an explicitly competitive environment, underscoring how important it is for us,” said Zink.

● Just viewing a superior human “player,” as opposed to a perceived inferior one or a computer, activated an area near the front of the brain that appears to size people up – making interpersonal judgments and assessing social status. A circuit involving the mid-front part of the brain that processes the intentions and motives of others and emotion processing areas deep in the brain activated when the hierarchy became unstable, allowing for upward and downward mobility.

● Performing better than the superior “player” activated areas higher and toward the front of the brain controlling action planning, while performing worse than an inferior “player” activated areas lower in the brain associated with emotional pain and frustration.

● The more positive the mood experienced by participants while at the top of an unstable hierarchy, the stronger was activity in this emotional pain circuitry when they viewed an outcome that threatened to move them down in status. In other words, people who felt more joy when they won also felt more pain when they lost.

“Such activation of emotional pain circuitry may underlie a heightened risk for stress-related health problems among competitive individuals,” suggested Meyer- Lindenberg.

In collaboration with other NIMH researchers, Zink and colleagues are planning follow-up studies to explore brain activity in response to the experimental social hierarchy in patients with mental illnesses like schizophrenia or autism, which are marked by social and thinking deficits. The researchers will also be exploring whether particular gene variants might differentially affect brain responses in similar experiments.

Also participating in the study were Yunxia Tong, Qiang Chen, Danielle Bassett, and Jason Stein, NIMH.
 

Key study findings included:
● The area that signals an event's importance, called the ventral striatum, responded to the prospect of a rise or fall in rank as much as it did to the monetary reward, confirming the high value accorded social status.

REFERENCES:
Zink CF, Tong Y, Chen Q, Bassett D, Stein JL, Meyer-Lindenberg A. Know your place: neural processing of social hierarchy in humans. "Neuron". 2008 Apr 24. Sapolsky RM. < http://www.ncbi.nlm.nih.gov/pubmed/15860617?ordinalpos=26&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Res ultsPanel.Pubmed_RVDocSum > The influence of social hierarchy on primate health. "Science". 2005 Apr 29;308(5722):648-52. Review. PMID: 15860617 Marmot MG. < http://www.ncbi.nlm.nih.gov/pubmed/16537740?ordinalpos=4&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Resul tsPanel.Pubmed_RVDocSum > Status syndrome: a challenge to medicine. "JAMA". 2006 Mar 15;295(11):1304-7. No abstract available. PMID: 16537740


 Date of upload: 23rd July 2008

                                  
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