Bi-plane and single plane angiography: a study to compare contrast usage and radiation doses for adult cardiac patients in diagnostic studies.

OBJECTIVE:: This study compares the performance of bi-plane coronary angiography against single plane angiography in terms of the volume of contrast used (ml) and the total dose-area product (DAP) (μGym2 ) to the patient measured directly via flat panel detectors.

METHODS:: A total of 5176 adult diagnostic cardiac angiograms from a hospital in Brisbane, Australia were retrospectively studied. Patients with aortograms, iliac or femoral artery imaging, and stenting or graft interventions were excluded. Student's t-tests were used to compare means, and confounding variables were compared using multivariate regression. This quantified the effects of bi-plane system use holding constant other factors (e.g.) body mass index (BMI), age, room, sex, number of digital acquisitions and fluoro time.

RESULTS:: Bi-plane imaging had an average difference in mean contrast use of -15.1 ml [15.5% 95% confidence interval (CI) (-13.2, -17.0) p<0.001], multivariate regression demonstrated a -27.0 ml reduction in contrast use [28% 95% CI (-29.0, -24.83) p<0.0001] when the significant effects of fluoro time, number of digital acquisitions, BMI and sex were held constant. Bi-plane imaging had an average difference in mean DAP of + 887.1 μGym2 [23% 95% CI (+1110.7, +663.4) p < 0.001], whilst multivariate regression found a +628.3 Gym2 increase in DAP [16% 95% CI (+467.5, +789.3) p<0.001] when the significant effects of fluoro time, number of digital acquisitions, BMI and sex were held constant.

CONCLUSION:: These results demonstrate that bi-plane imaging uses less contrast media than single-plane imaging for coronary angiography at the expense of more radiation. Bi-plane imaging may be preferable in patients with renal impairment, however single plane imaging may be preferable in those without renal impairment.

ADVANCES IN KNOWLEDGE:: This is a large cohort and statistically comprehensive study comparing bi-plane and single plane coronary angiography. Other studies 4, 5, 6, 12 have used Student's t-tests to measure the difference between means, however this provides no causative information on the differences found. This study provides a view of the causative impact of bi-plane usage on DAP and contrast use via multivariate regression modelling.