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.