Fatal cancer deaths from CT scans half of previous estimates

A recent article regarding the incidence of cancer caused by CT scans was published in the Annals of Internal Medicine (1). The American College of Radiology has already published its own response (2). This topic is sure to attract the attention of the media and concerned patients who have recently weathered a similar storm regarding mammography.

All concerned parties should know that this article does not report an increase in the estimated rate of cancer caused by CT scans. In fact, it reports the opposite. However, it reports an increase in the number of cancers cased by the 3-fold increase in the number of CT scans done in the US since 1993. The projection of about 29,000 fatal and non-fatal cancers cased by about 70 million CT scans translates to about a 1 in 2400 chance of getting cancer from a CT scan, taking all patients together. However, the odds changed to about 1 in 2000 when the authors removed from the denominator patients who died (or were projected to die) within 5 years of the scan, before any radiation-induced cancer could develop, and patients with cancer at the time of the scan. The FDA estimated the odds of getting a fatal cancer to be 1 in 2000 (3), using cruder methods. Assuming a 50% cancer fatality rate, the new projections actually show the risk of fatal cancer from CT scans is half of what was previously thought.

A second article (4) will rightly cause even more alarm. This report analyzed the actual radiation doses delivered by four CT centers in the San Francisco area. These doses were both variable between centers and higher than assumed to be normal across the country. Thus, the calculated cancer risks were higher for these patients than in the other theoretical article, and these outlying data are the ones quoted by the media (5). Wake up, imaging centers! This article calls upon you to assure your scans are done with the minimum of radiation exposure to your patients.

Radiologists around the world are already striving to reduce the amount of radiation exposure for all types of CT scans and other methods that use ionizing radiation (6, 7). Alternative modalities are recommended whenver possible to achieve the same purposes (8). Each time a CT is planned, physicians must weigh the risk of inducing cancer against the potential benefit of the scan. Non-radiologists must not forget that CT scanners represent and unquestionalbly beneficial technology that has helped avoid exploratory surgery, provided guided interventional procedures to avoid other types of surgery, offered early diagnosis of disease to allow earlier and more effective treatment, and saved countless lives.

1. Original article http://tinyurl.com/yef4svl
2. ACR response http://tinyurl.com/ydqs338
3. FDA article http://tinyurl.com/m8cvxa
4. Second original article http://tinyurl.com/yevb6mt
5. WSJ article http://tinyurl.com/y9eko3b
6. Image Gently in pediatrics http://tinyurl.com/yagxrtv
7. Image Gently expansion http://tinyurl.com/y9f34d5
8. ACR appropriateness criteria http://tinyurl.com/ybcwvxr

The musculoskeletal session overflowed into the hallway, where monitors were set up for those who could not get in the room. The new format combined review course lectures with scientific presentations, and this worked very well.

Is that herniation acute or chronic?

Is there dehydration? It does not matter, since normally hydrated discs and desiccated discs can herniate. Herniated discs dehydrate in 8-20 weeks.

Are there osteophytes? Phytes take about a year to form, so they indicate chronic disc problems. However, they do not protect a disc against a new herniation. You can have bulging for years, osteophytes for years, and still get a new herniation at that level.

Are there endplate signal changes? There are four types, three common types and one not so common:

1. Fibrovascular changes.

2. Fatty changes.

3. Sclerotic changes.

4. Degenerative cysts.

All of these take about a year or so to form, but none protect against new herniations.

The presence of these chronic changes (phytes, endplate changes) indicates only that there have been problems at the corresponding levels for a year or so.

Absence of these changes does not mean that the disc is definitely new, but it would be hard to say a disc herniation is definitely old without these changes present or an old scan showing it was present before.

Also, while new herniations can degenerate over time, and degenerated discs can herniate acutely, there is no such thing as a "degenerative herniation." That is, degeneration of a disc cannot cause it to herniate. Only trauma can cause a herniation.

The image of two MRI scans included here shows a degenerated L4-5 disc with desiccation, narrowing, and osteophytes that herniated acutely four years after the first MR.

Slow Down

I am listening to a wonderful lecture about slowing down the pace in your life to improve your quality of life. This is the philosophy that underlies my recent decision to suspend my clinical work until the beginning of next year so I can devote proper attention to other things on my schedule, including medico-legal reviews, depositions and trials, holidays and vacations, and the biggest and best radiology meeting of the year, the RSNA.

You can download or listen to the lecture by Carl Honore at Learn Out Loud at the following link:

http://tinyurl.com/ydz72de

Video Report of MRI

Video reporting can be very helpful for attorneys who would like the images explained at a mediation with words "from the horse's mouth." I don't see it as a good substitute for a typewritten or multimedia report for use by physicians, but it could be a good adjunct in complicated cases.

Starting a Blog

This blog will serve as a way of delivering news and info to my students, referring physicians, and attorney clients. Not sure yet how it will interface with Google Wave, Twitter, Podcasts, etc. Check back again later if this is all you see here!

Topics will include: MRI, personal injury radiology, brain injury, MTBI, DTI, PET, radiology, spine, disc herniation, plaintiff and defense, errors in radiology, imaging centers, and who knows what else...