It is estimated that the growth rate of cardiac imaging is approximately 26% per year. Of this growing number, many patients are referred to centers which use a more expensive but a reportedly “more accurate” method of 64-row CT angiogram.
A recent study by Miller et al, a group at Johns Hopkins in Baltimore, examined 64-row CT angiography versus conventional angiography and found no overall benefit. This study (reported in the November 27, 2008 issue of The New England Journal of Medicine) was performed as follows:
CT Angiography Study Question
Is CT angiography as accurate as conventional angiography in patients with suspected coronary artery disease?
Angiogram Study Method
Patients underwent calcium scoring, multidetector CT angiography and then conventional angiography.
291 patients (with calcium scores of 600 or less) were examined at 9 centers.
The physician group, using an independent laboratory, looked at diagnostic accuracy and subsequent revascularization status.
Study Results - Accuracy of CT angiogram versus conventional angiogram
- CT angiography was found to be as accurate but similar to conventional angiography in the ability to identify patients who underwent revascularization.
- Disease severity detected by both CT and conventional angiography was well correlated (the same).
Angiography Study Conclusions: Is 64 row CT “better” than conventional “regular” CT?
In this study, the authors concluded that no, 64 row CT angiography (although just as accurate) cannot replace conventional angiography at present.
In the same issue of the New England Journal of Medicine, Drs. Redberg and Walsh, out of UCSF in California, wrote a perspective outlining the following risks and benefits of CT angiography:
Benefits OF CT Angiography:
- Speed - CT angiography is much faster than conventional, only taking 10 minutes.
- Enhanced photos - 64 row, multidetector CT angiography produces high resolution, color, 3D images of the heart and vessels; “prettier pictures”.
Risks Of CT Angiography:
- Greater level of radiation - Dr. Redberg describes CT angiography as “bombarding patients with radiation many orders of magnitude greater than traditional radiographs”. In her perspective, Dr. Redberg refers to a study from Brenner and Hall that estimates that 1.5 to 2.0% of all cases of cancers in the United States may be attributed to CT radiation.
- Expense - The expense of CT angiography is, at present, a heated item of debate amongst Medicare funding proponents and foes.
- Greater incidental findings - CT angiography may lead to greater “incidental findings” which can lead to additional procedures (often found to be unnecessary) such as: biopsies, revascularizations and additional diagnostic tests.
These important results and opinions reflect not only the concern for individual patient overall long term health but also mirror present day economical concerns and the impending landslide of questions that will be weighed amongst patients, clinicians and government agencies in the near future.
