Utility of Image Magnification Software to Reduce Radiation Emission During Invasive Coronary Angiography

Background:
Image acquisition at high magnification during invasive coronary angiography (ICA) increases emitted radiation. In this study we examined the effect of performing ICA at lower than standard magnification compared to standard magnification on 1) emitted radiation and 2) image quality, while using post image acquisition magnifying software.

Methods:
ICAs were randomly performed at “22 cm” (standard) magnification or “42 cm” (low) magnification. To account for factors affecting radiation emission, all studies were performed by one operator with the same equipment and same technique. Radiation emission, measured in milli Gray (mGy) was recorded at the end of each case from the x-ray equipment radiation monitor. All studies were reviewed by one experienced blinded angiographer. Post image acquisition magnifying software was available to magnify images in either group as necessary. Image quality was graded as good to excellent, adequate or inadequate. Adequate quality was defined by meeting all the following criteria: 1) ability to see all the major coronary arteries and their main branches (>= 2mm) in their entirety, 2) ability to assess lesion severity and length, 3) ability to assess collateralization.

Results:
74 studies were performed; 37 by the standard and 37 by the low magnification technique. Patients in the low magnification and standard magnification arm had similar age (65.1 vs 66.6 years), weight (201.6 vs 197.3 pounds), height (69.5 vs 68.8 inches) and body mass index (29.1 vs 28.9 ) respectively. Total radiation time was similar between the standard and low magnification groups (2.4 vs 2.2 minutes) respectively. Post image magnifying software was used to review all images in the low magnification group and none of the images in the standard magnification group. Emitted radiation was significantly lower (42%) in the low versus the standard magnification group (145.5 mGy vs 250.8 mGy, p<0.01). All images in both groups were graded as adequate to excellent.

Conclusions:
Performing ICA at lower than standard versus standard image magnification, and utilizing post-acquisition image magnifying software significantly reduces radiation emission without adversely effecting image quality.