Cold Carbonated Water Reduces Interference from Extracardiac Gastric Activity During 82Rb PET in Patients

Cold carbonated water is a simple, inexpensive preparation that could plausibly reduce gastric uptake through a combination of gastric distension, altered motility from CO2, and reduced mucosal perfusion from cooling. To our knowledge, this approach has not been investigated in the setting of 82Rb PET myocardial perfusion imaging. Methods: We conducted a same-day, within-subject study of 20 patients undergoing surveillance for cancer therapy-related cardiac dysfunction and included 20 additional patients from the same cohort who did not receive the intervention. Each patient underwent 2 rest 82Rb PET scans; between scans, each drank up to 500 mL of cold carbonated water. Gastric spillover was assessed in 3 ways: subjective comparison (better/worse/unchanged), a 4-level semiquantitative interference severity score, and quantitative myocardial-to-extracardiac (MYO/EXT) ratios using voxel- and contour-based region-of-interest methods. Results: Severity scores shifted lower after the intervention (P = 0.003). The scores for 11 of 20 patients improved, 9 were unchanged, and none worsened. MYO/EXT uptake ratios increased with both region-of-interest methods (voxel: from 1.67 ± 0.61 to 1.98 ± 0.50, P = 0.041; contour: from 1.60 ± 0.34 to 1.82 ± 0.37, P = 0.006). Readers judged improvement in 75% and 80% of cases, respectively, with 75% concordance. In contrast, the nonintervention group showed no significant differences in semiquantitative scores or MYO/EXT uptake ratios between scans. Conclusion: Cold carbonated water reduced gastric interference during rest 82Rb PET myocardial perfusion imaging across visual and quantitative metrics. The intervention is simple and well tolerated. Larger, controlled studies, especially during stress imaging, are warranted.