Considerations in screening CT scans
Given the recent interest in CT coronary angiogram as a tool for health screening of perfectly healthy patients, this has raised certain issues, and it is always wise for a patient to understand the potential problems, and consider them carefully before doing this scan. These issues often apply to CT colonoscopy as well.
1. Radiation concerns
 Radiation dose in a CT coronary angiogram is at least 2 years of equivalent background radiation time. CT colonoscopy carries at least a similar dose, probably more.
Risks include malignancies – read : cancer – like leukemia and soft tissue sarcomas. There can also be genetic mutations that may be inherited by the offspring, which must be a consideration for patients who are still planning for more children. The risk may be rare, but as always, to the unlucky one who is struck with cancer, it is a very real, life-threatening problem.
2. The risk of contrast
There is a possibility of having an allergy to the intravenous contrast medium. Allergic reactions may range from mild rash, to angioedema and even life threatening airway obstruction and anaphylactic shock. These may happen rarely, but again, not something to brush off lightly.
For patients with renal failure, intravenous contrast may worsen renal function. Diabetic patients must follow medical advice regarding metfomin, due to a risk of transient renal failure.
3. Incidental findings
A CT scan of the coronary vessels just not just include the coronary vessels. It includes practically the whole thorax, and part of the upper abdomen, and there is a possibility of incidental findings. Perhaps a nodule in the lung or the mediastinum. Perhaps a nodule in the liver or the adrenal gland. These incidental findings may require further work-up and investigation, which may be expensive, and merely prove that they are benign.
Even a positive finding of a soft plaque in an otherwise asymptomatic, fit patient may cause a dilemma. In such a case, is a PTCA indicated ? If not, what if the patient subsequently suffers a heart attack?
As such, using these as a screening tool is not recommended without due consideration. For those with worrying symptoms of chest pain or left arm or shoulder pain and numbness, the benefits will probably outweight the dangers, but for fit, asymptomatic patients, the benefits of the scans is still not proven.