Excerpt

We enjoyed reading the critical appraisal of Farzaneh-Far A. et al1 addressing the potential of PET/MR imaging in cardiovascular disease.2 We certainly agree that the application of various radiotracers in nuclear cardiovascular imaging may carry a “minimal and calculated” increased risk of cancer manifestation when patients are exposed to low-dose radiation such as with FDG (≈6–8 mSv).3 The problem in assigning an increased risk in cancer manifestation due to low-dose radiation exposure, however, is related, at least in part, to the high incidence of non-radiogenic cancer in industrialized countries and also to the observation that ionization is a weak carcinogen in comparison to many other toxins to which humans are exposed. Although there is no recognizable increase in cancer below cumulative radiation exposure less than 100 mSv,4 a minimal risk cannot be excluded for exposure of the patient to radiation by nuclear imaging techniques and cardiac CT.3,5 Notably, even cardiac magnetic resonance imaging may potentially impact the integrity of human DNA as demonstrated more recently.6 It is important to bear in mind that the intrinsic lifetime risk of dying from malignancy in the U.S. is approximately 21%.4 In this direction, 10 mSv of ionizing radiation from nuclear cardiovascular imaging techniques or cardiac CT could add 0.05% to that risk in absolute terms (a relative increase of 0.2%) and thus may reflect a minimal risk for cancer manifestation, if at all. In view of this potential minimal cancer risk, cardiovascular nuclear imaging and also CT are performed according to the ALARA principle (as low as reasonably achievable) with application of the lowest radiotracer dose while maintaining diagnostic image quality with the clinical benefit for the patient.3 …