January 1, 2010 Journal Watch summarizes a remarkable article entitled “Investigation of incidental findings on cardiac CT.” The article was based on a study conducted at a Canadian institution where the investigators evaluated the incidence, clinical importance, and costs of these incidental findings.
It’s first important to note that these researchers used the word incidental as equivalent to the word, occult. In medical imaging, an occult finding is an unexpected finding that has clinical consequence. Such findings are made with great frequency and have dramatically improved the lives of many. For example, a chest x-ray searching for a rib fracture reveals a lung cancer mass which was otherwise completely unexpected. A CT scan of the abdomen performed because of a complaint abdominal pain reveals a dissection of the thoracic aorta.
The Canadian researchers are strangely troubled by the discovery of unexpected conditions. The test they are evaluating is cardiac CT. Imaging data obtained during a cardiac CT includes imaging information of structures or tissues outside the heart. in an examination of 966 consecutive patients who underwent cardiac CT during 12 months at a single Canadian institution, incidental findings were noted in 401 patients. 12 of the patients were found to have clinically significant conditions, many of them, life-threatening without treatment.
Even if one accepts the very conservative assessment that only 12 of the patients were found to have clinically significant conditions, that means that 3% of everyone who had a cardiac CT performed had a condition that might have seriously harmed or killed them if it had not been accidentally seen in this study.
The researchers do not see the benefit derived by the 3% as a bonus. They don’t question that all the patients benefited from having a cardiac CT. In fact, no one questions that this method of scanning provides an important and noninvasive method of evaluating patients suffering coronary calcification and arterial disease. However, 68 patients exhibited incidental findings such as nodules or cysts in the lungs or liver. There’s the rub.
Confronted with 68 patients of the 401 who had abnormalities deemed to be indeterminate (undetermined significance) researchers worry that the abnormalities found might lead some to conduct further testing or evaluation. The solution, as they see it, is to not format the data concerning non-cardiac tissue and structures. They want to ask patients to consent to keeping the non-cardiac information invisible. If they see no “evil”, they need speak no “evil.”
I think this is insanity.