Pulmonary blood volume as a marker of adenosine-induced cardiac hyperemia: A Rubidium-82 study

PURPOSE: To investigate the efficacy of pulmonary blood volume (PBV) as a marker of the cardiac hyperemic response to adenosine during myocardial perfusion imaging (MPI).

METHODS: Forty healthy subjects underwent four consecutive Rubidium-82 rest/adenosine-stress MPI: two sessions were conducted without any caffeine consumption (baseline), while the remaining two sessions involved controlled caffeine consumption (arm 1: 100 and 300 mg; arm 2: 200 and 400 mg). We evaluate the ability of the stress-to-rest ratio of PBV (PBV ratio) to identify an adequate cardiac hyperemic response. The adequate hyperemic response was defined as a stress myocardial blood flow >2 mL/g/min and a corresponding myocardial flow reserve >68% of the maximum myocardial flow reserve obtained during the baseline scans.

RESULTS: Based on 126 MPI sessions conducted in 40 subjects, the PBV ratio demonstrated a sensitivity of 78% and a specificity of 74% in detecting adequate cardiac hyperemia. The positive predictive value was 95%, while the negative predictive value was 36%.

CONCLUSION: The PBV ratio permits the identification of adequate hyperemic response with sensitivities and specificities comparable to existing markers.