Radiation During Cardiovascular Imaging

Ariel Roguin; Prashant Nair

Disclosures

Br J Cardiol. 2007;14(5):289-292. 

In This Article

Case History

A 52-year-old man with cardiac risk factors of hypertension, type 2 diabetes, hypertriglyceridaemia, low high-density lipoprotein (HDL), obesity, positive family history of early coronary artery disease, and atypical anginal symptoms was referred for cardiovascular evaluation. Treadmill stress test was not conclusive, as he did not reach his target heart rate. Echocardiography was normal. He was referred for a dipyridamole dual isotope nuclear stress test, which showed lateral wall reversible ischaemia. Coronary angiography was recommended. The patient was concerned and anxious, and elected to undergo MSCT angiography, which revealed an elevated calcium score and significant coronary narrowing in the left circumflex and right coronary arteries. Coronary angiography had similar findings and the lesions were treated with stents.

Our patient underwent echocardiography that uses ultrasound energy and has no ionising radiation. Echocardiography allows estimation of heart and valve function but not of the coronary arteries. The same is true for cardiac magnetic resonance imaging (MRI), although it is much more expensive.

As he did not complete his treadmill stress test (no radiation), a pharmacological stress test was used. A dobutamine echocardiography stress test has no radiation and is excellent for this purpose, but a nuclear scan was ordered and, based on the results of this test, the patient’s history, medical therapy and risk profile, a coronary angiography was ordered. However, our patient and his wife were still very worried and hesitant about the need for an interventional procedure. After being exposed to the debate in the media concerning computed tomography (CT) in cardiology, our patient referred himself to MSCT angiography.

In the cardiovascular evaluation of our patient, he was exposed to the following ionising radiation: treadmill stress test (0 mSv), echocardiography (0 mSv), dipyridamole nuclear stress test (thallium + technetium; 25 mSv), calcium score (2 mSv), MSCT angiography (10 mSv) and diagnostic coronary angiography (5 mSv), for a total of about 42 mSv. This is equivalent to 2,100 chest X-rays or the approximate equivalent period of natural background radiation of 17 years. The percutaneous intervention was not complex and was associated with approximately an additional 15 mSv of ionising radiation. If we follow this patient with a dual isotope cardiovascular nuclear scan (25 mSv), he will be exposed to an equivalent of approximately 1,250 chest X-rays every time he has the test.

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