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Biotech Science

Cheap Blood Clot Detection Device 103

Posted by kdawson
from the but-wear-your-helmet dept.
Gearoid_Murphy writes "The BBC details the news of a cheap handheld device to detect blood clots on the surface of the brain. The device uses infrared light to penetrate 3 cm into the body; light that has passed through clotted blood changes detectably. A doctor who is testing the device in India said, 'We found a 98% accuracy for showing blood clots or haematomas.'"
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Cheap Blood Clot Detection Device

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  • Company Website... (Score:4, Informative)

    by appleguru (1030562) on Sunday April 15, 2007 @09:20PM (#18745957) Homepage Journal
    http://www.infrascanner.com/ [infrascanner.com]

    Looks like they're based in PA, USA... But due to US regulations, they aren't allowed to test the device on patients in the US, and have outsourced such clinical testing to India.
  • by Anonymous Coward on Sunday April 15, 2007 @09:59PM (#18746235)
    In fact, they are using CTs to confirm the diagnosis...so the implication is that the hand held device is missing 2% of the cases that the CT is catching...at a great cost savings (what was that speech from fightclub about the recall formula?)...that might be the reason why the device isn't cleared for use in the states.
  • by Anonymous Coward on Sunday April 15, 2007 @10:29PM (#18746391)
    In developing a new technology, it's common to compare it's performance to the current 'gold standard'. Also, the device doesn't have to be perfect to be useful. It could be used as a first pass, and then a subsequent CT scan could be done on the patients that get a negative test result. It would be nice if the article gave the sensitivity and specificity so we would know what makes up its '98% accuracy'.
  • by fukitznukin (1088811) on Sunday April 15, 2007 @10:34PM (#18746437)
    The other way to look at it is to compare infrared to the current modalities. For example, MRI which provides very sophisticated images, picks up 96% of brain injuries including blood clots. However, this is a very expensive test and is time consuming. In my hospital, I can get a STAT MRI and a radiologist's report in 1-2 hours. If it's after hours, a team has to be called in to do the test and then you can add at least another 45 minutes. Infrared testing on the other hand is a bedside test that can be done very quickly and inexpensively. From a general perspective, 98% is not just adequate it is much better than most tests used in medicine. An EKG that is done for heart attacks for example can miss up to 50% and most people are relieved when they are told that the EKG is normal. 98% accuracy is almost unheard of in medical testing. The term accuracy includes the effects of false negatives and false positives so 98% accurate does not necessarily mean that 2% of the true positives are missed, the test could be picking up all the true positives but also some false positives (it overcalls the number of abnormal test results). Additionally, a test that is 98% accurate does not mean that 2% of the people die unless of course you are referring to a uniformally fatal disease of which blood clots on the brain do not belong. A subdural hematoma is one type of blood clot on the brain and its mortality is about 60%. Additionally, if you think about it, the 2% of blood clots that are going to be missed (let's say the miss rate is 2%) will be the smallest 2% of the blood clots and therefore the least lethal. Yes, size does matter when it comes to blood clots on the brain.
  • by Anonymous Coward on Sunday April 15, 2007 @10:53PM (#18746545)
    TFA did say that the alternative - a CT scan - gives a better image. Point is it's anything but cheap or portable.

    "The infrascanner will never replace CT scans - but could be a highly useful new piece of medical technology."
  • How it works (Score:5, Informative)

    by c_fel (927677) on Sunday April 15, 2007 @10:54PM (#18746549) Homepage
    Hemoglobin has a different absorption spectrum when it's oxygenated (oxyhemoglobin) or not (desoxyhemoglobin). An interesting characteristic of this spectrum is observed in the near-infrared part or light (700-850nm): http://omlc.ogi.edu/spectra/hemoglobin/index.html [ogi.edu]

    In the infrared part, oxyhemoglobin absorbs less light than desoxyhemoglobin ; it's the contrary in the red part. So if we shoot these near-infrared wavelengths (and some more, to get a good idea of the absorption spectrum) in the head and detect it somewhere else (around 5-6cm from the source), we can get information on the concentration and oxygen level of the hemoglobin in the middle of the emitter and the detector. If the hemoglobin is more present than somewhere else in the head, and it's less oxygenated than usually, we get a good idea that there's something wrong there.

    Other advantages : infrared light is non-ionizing, so it's absolutely no dangerous to use that kind of instrument continuously on a person until we are sure there's no problem.

    It's brilliant and I'm glad to see that kind of instrument emerging.
  • Errr... (Score:5, Informative)

    by Anonymous Coward on Sunday April 15, 2007 @11:13PM (#18746649)
    I don't entirely agree...

    Aside from the fact that a lot of the time, we're more worried about post-op *bleeding* (which we'd see on CT) than simple clotting, I'm not sure how you'd tell appropriate clotting from dangerous clot, *except* through monitoring symptoms. Its not the clots after surgery that are dangerous, but when the clots are in areas that suffocate healthy tissue (ischemia).

    And a CT looking for new infarct would be useless. An MRI might help, but not a CT.

    And, yes, IAAD.

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