His curiosity gets the better of him; he goes up to the balding man and asks him what he is doing. The man says, "I'm sending out 1,000 Valentine cards signed, "Guess who?'

"But why?" asks the man.

"I'm a divorce lawyer," the man replies.

A recent review article in the New England Journal written by radiology researchers at Columbia University brought attention to the radiation exposure from CT scanning. Its use has transformed medical imaging by providing a three dimensional view of the organ or body region of interest. The numbers of CT scans have also increased dramatically both for diagnosing symptomatic patients and for screening for lung, colon, and heart disease in asymptomatic people. The pediatric population has found a much higher use for CT scanning especially for diagnosing acute appendicitis. It is estimated that more than 62 million CT scans per year are currently obtained in the United States including at least 4 million in children. Epidemiologic studies indicate that the radiation dose from even two or three CT scans results in a detectable increase in the risk of cancer especially in children. In pediatric populations the faster scanning times, often less than one second, are partly responsible for its increased use. It has also found to be very cost effective. Though no large scale epidemiologic studies of cancer risk associated with its use have been reported there is one such study under way. The authors note that CT scans are often ordered excessively and often repeated unnecessarily especially in the practice of defensive medicine. They present three ways to reduce the overall radiation exposure from CT scanning. First to reduce CT related dose in individual patients, second to replace CT with ultrasonography or MRI imaging if feasible and, the third and most effective way is to simply decrease the number of CT studies that are ordered. The study certainly is food for thought. (Brenner DJ and Hall EJ. Computed tomography - An increasing source of radiation exposure. N Engl J Med 2007 Nov 29;357:2277)

Approximately a quarter of a million patients have out of hospital cardiac arrests yearly, but in hospital cardiac arrests are probably double or triple that number. Fewer than 30% in hospital arrests survive to discharge. Survival is dependent on prompt defibrillation when the arrest is due to ventricular tachycardia or ventricular fibrillation. Out of hospital arrests where there are readily available automated external defibrillators (AED's) have pushed the survival above 50%. A recent article by Chan and colleagues in the New England Journal analyzed nearly 7000 hospitalized patients. They used the bench mark of defibrillation within two minutes. If defibrillation occurred within two minutes survival to hospital discharge was 39% but if it occurs after two minutes it went down to 22% with worse functional and neurologic recovery. Obviously, hospitalized patients have other co-morbidities which may account for the lower survival. However this study showed that delayed fibrillation was also more common during after hours cardiac arrest and placing patients in unmonitored units. Most patients probably assume that a hospital would be the best place to survive a cardiac arrest. This study sheds some doubt on that assumption. It shows that hospitals could improve on this very important patient safety issue. (N Engl J Med 2008 Jan 3;358:9)

Obese men with prostate cancer tend to have poorer outcomes than normal weight men. This retrospective study of over 13,000 men found that obesity was also significantly associated with a lower PSA level. Because obese men have larger plasma volumes, it is felt that hemodilution explains these lower levels. Men in this study with BMI's greater than 35 had 11-21% lower levels and 21-23% larger plasma volumes than normal weight men. These lower levels may lead to delayed diagnosis of prostate cancer in obese men. Clinicians need to be aware of this relationship. (Banez LL et al. Obesity-related hemodilution and PSA concentration among men with prostate cancer. JAMA 2007 Nov 21; 298:2275)

John J. Mohr, M.D.