Fine tuning virtual colonoscopy—a faster, better, less expensive screening test for colon cancer?

Bill Crounse 2007 03I happen to be old enough to have had a screening colonoscopy on two occasions.  As anyone who has had this procedure performed will know, the exam itself isn’t nearly as bad as the preparation for it.  With good sedation, one hardly remembers the procedure.  However, drinking a gallon or so of go-litely bowel prep and then waiting for your gut to evacuate has never been high on this doctor’s list of favorite things to do.  For that reason alone, many people avoid having a screening colonoscopy even though it is a test that can save lives by detecting cancer early.

Avoiding the nasty prep and the invasive (some would say embarrassing) test are reasons why many people are attracted to an alternate test called “virtual” screening colonoscopy.  In this test, a CT scanner replaces the colonoscope, but unfortunately the gut-cleaning prep is still required.  The American Cancer Society has added virtual colonoscopy to its list of recommended screenings and studies have shown that the virtual exam is as reliable as the scope method in finding polyps or cancer (New England Journal of Medicine).

Now, clinicians at the Massachusetts General Hospital are testing a concept that could make virtual colonoscopy faster, less expensive and even easier for the patient.  Using the magic of computers and software, it is possible to digitally remove the normal contents of the gut and make the inside of the gut appear just as if the patient had done the usual bowel evacuation prep.  However, one issue with the virtual “cleaning” has been the amount of time needed to process the CT images so they can be interpreted by clinicians.  The time needed to run the necessary computer algorithms can take up to 60 minutes for each exam, far too long to be practical.  So Dr. Hiro Yoshida, a researcher with Massachusetts General who developed the datagram transport layer security (DTLS) algorithm used to electronically clean virtual colonoscopy images, knew it needed to be done faster.  Using Microsoft’s high performance computing (HPC) platform, Microsoft .Net 4.0, and the Intel Parallel Studio 2011 developer tool suite, researchers were able to reduce the time needed to run the algorithms from 60 minutes to just 3 minutes.  This might very well lead to faster, less expensive virtual exams that are also much more pleasant for patients because no bowel prep is required.

The collaboration also:

  • demonstrates advanced visualization capabilities with 2D to 3D conversion, gesture-based (multi-touch) navigation and computer-aided diagnostics on Windows 7 powered devices, including a Slate device, Windows Phone 7, or desktop PC
  • leverages Intel’s multi-core processor technologies, enabling programmers to make performance and reliability improvements to applications
  • uses a fully parallelized GPU-based volume rendering engine developed by Microsoft Research
  • demonstrates the capability to do high performance CPU and GPU-based computing with Windows HPC and .NET for colon cancer screening

Virtual Colonoscopy courtesy Massachusetts General Hospital

One disadvantage of virtual colonoscopy is that if a polyp or cancer is discovered with the CT scan, a patient must undergo a standard colonoscopy for final diagnosis and treatment.  However, as a screening test the virtual exam is likely to be favored by many patients who would rather avoid the prep and inconvenience associated with traditional colonoscopy.  By working together, computer scientists and clinicians may be finding ways to make virtual colonoscopy even better and more attractive to patients.  If so, many more lives could be saved.

Bill Crounse, MD             Senior Director, Worldwide Health             Microsoft

Comments (10)

  1. MP says:

    WONDERFUL,Ive had 3 procedures already, YUCKY!!

  2. Jo McDaniel says:

    We have a family history of colon cancer and need to be tested every year. The cost and prep have discouraged many of us not to undergo the testing. We would appreciate this test so much w/o the cost and the prep!! Thank you so much. When will this be available and will insurances cover it?

  3. Tom says:

    How about the high radiation exposure from a CT scan ?

  4. hlthblog says:

    Jo and Tom,

    Virtual colonoscopy has been available for several years now.  What is new is faster processing of the images and the ability to "electronically" clean the colon.  This elimiaes the the need to purge prior to the test.  The downside is that if something abnormal is found, the patient will then need a standard optical colonoscopy for further evaluation and treatment.  And yes, radiation exposure  from CT is something to consider especially if you have had other abdominal CT scans or lots of xray exams in the past.

    Bill Crounse, MD

  5. Gary Lee says:

    Is this available on the west coast?  Where?

  6. hlthblog says:


    Thanks for writing.  I don't keep an inventory of medical centers that offer virtual colonoscopy.  However, I'm quite certain the procedure is available in medical centers other than mentioned in my blog post.  I would expect almost any major medical center in large metropolitan areas and especially academic medical centers to offer virtual colonoscopy as an alternative to the endoscopic procedure.  Keep in mind that there are advantages and disadvantages to both procedures.

    Bill Crounse, MD

  7. Gary Lee says:

    I was asking about the virtual colonoscopy that doesn't require the cleansing process, the one that Mass General is doing, a virtual cleanse.

  8. hlthblog says:


    Yes, I understood what you were asking.  We are talking about the same thing. If you have a physician, ask him or her if the procedure is offered where you live.


  9. Gary says:

    OK, contacted Stanford University Imaging, never heard of it, UCSF China Basin Imaging, never heard of it, Mayo clinc in Scottsdale Arizona, never heard of it, my Dr.s never heard of anything!  That's why I'am looking for it.

  10. hlthblog says:


    I really cannot believe that no one at Stanford has heard of "virtual colonoscopy" via CT scan.  Did you check with their imaging department?  None-the-less, as a physician I wouldn't recommend this test.  It comes with exposure to radiation, and there is still some prep needed before the test.  Also, if something is found during the CT exam, you would then have to have a standard colonoscopy for biopsies or polyp removal.  For most people it is the prep that is the unpleasant part of standard cononoscopy.  The procedure itself is a breeze thanks to medication you'd be given.  You won't remember a thing about it.  Of course it is your choice and that of your docotr, but if I needed an exam I'd go for the standard test.  And yes, I've had it done (twice) so I know what I'm talking about as a patient as well as a doc.

    Bill Crounse, MD

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