Role of carbonated water technique to enhance Tc-99m tetrofosmin myocardial perfusion imaging by reducing subdiaphragmatic artefacts.

Objective: Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is confounded by the extracardiac artefacts cause by hepatobiliary clearance of the radiotracers. Various techniques have been evaluated to lessen those artefacts. In this study, we endeavoured to determine the effect of carbonated water in reducing such infracardiac artefact so to improve MPI image quality, sensitivity and specificity.

Methods: A total of 1000 patients were prospectively enrolled and randomised into two equal groups as A and B. Group A were given 250 ml of carbonated beverages and Group B were given 250 ml plain water immediately after radiotracer injection. Images were evaluated qualitatively and quantitatively for the interfering extracardiac artefacts.

Results: The qualitative analysis favoured carbonated water in reducing the interfering intestinal activity during rest as well as stress (p = 0.005 and p < 0.001, respectively). Quantitative calculation showed significant improvement of myocardium to extracardiac ratio with carbonated water ingestion in rest (p = 0.031) and vasodilator stress studies (p = 0.004). However, for exercise stress studies quantitative evaluation were not statistically different between the two protocols (p = 0.855).

Conclusion: Carbonated water ingestion is an easy and effective way to enhance SPECT image quality by mitigating extracardiac artefacts.