they never stop to ask if they should do something.” This sentiment, voiced by a Michael Crichton character in Jurassic Park, encapsulates the themes presented in a perspective published in today’s New England Journal of Medicine.
Dr. Michael S. Lauer from NHBLI, who spoke with Cardiovascular Business News about his perspective, comments on a retrospective analysis in the same journal. The analysis found nearly 700,000 non-elderly people out of approximately one million underwent at least one medical imaging procedure over a three-year period.
In the study, Fazel et al found that of these 700,000, approximately 20 percent received a moderate dose of radiation, which ranged from 3 mSv – 20 mSv. Less than 2 percent received high to very doses. While the majority of the people in the study only received 2.4 mSv, the authors deemed “imaging procedures an “important source of exposure to ionizing radiation in the United States.”
The researchers also found that CT and nuclear imaging accounted for the vast majority of the cumulative dose. More specifically, myocardial perfusion imaging alone accounted for 22 percent of the total effective dose. And, more than 80 percent of the imaging took place in outpatient settings.
In response to these findings, Lauer said that medical imaging procedures, with the exception of mammography, have not proven their benefit to counteract the potential cancer risks associated with these radiation doses, or their costs. He stressed the necessity of launching large-scale randomized, controlled trials to address these issues for various patient populations.
As a result of this lack of hard evidence, Lauer said that most imaging protocols should be re-evaluated, specifically highlighting imaging protocols in cardiovascular medicine as being unsupported by conclusive data. “We don’t know if these tests save lives or prevent heart attacks,” he said.
Dr. John Lesser, from the Minneapolis Heart Institute, said in an interview that these procedures help practicing cardiologists to diagnose and treat their patients. He also mentioned that much research has ensued to reduce radiation levels in newer techniques and technologies, such as CT.
Also, Lesser noted that while randomized, controlled trials would be helpful, he said they would require a great deal of funding and effort. He also highlighted the complexity of a trial that would attempt to prove or disprove that medical imaging improves longevity or reduces mortality because they are diagnostic tests, and not procedures.
The affect of this NEJM study and perspective remains to be seen, but the lines are already being drawn about how people will choose to employ medical imaging procedures in clinical practice. Hopefully, this will serve to further inform a community in need of hard data.
On these topics, or any others, please feel free to contact me.