Assessment of coronary vasoreactivity by multidetector computed tomography-feasibility study with rubidium-82 cardiac positron emission tomography

Abstract

Background: Positron emission tomography (PET) during the cold pressor test (CPT) has been used to assess endothelium-dependent coronary vasoreactivity, a surrogate marker of cardiovascular events. However, its use remains limited by cardiac PET availability. As multidetector computed tomography (MDCT) is more widely available, we aimed to develop a measurement of endothelium-dependent coronary vasoreactivity with MDCT and similar radiation burden as with PET. Methods and Results: A study group of 18 participants without known cardiovascular risk factor (9F/9M; age 60±6 years) underwent cardiac PET with 82Rb and unenhanced ECG-gated MDCT within 4 h, each time at rest and during CPT. The relation between absolute myocardial blood flow (MBF) response to CPT by PET (ml·min -1·g -1) and relative changes in MDCT-measured coronary artery surface were assessed using linear regression analysis and Spearman's correlation. MDCT and PET/CT were analyzed in all participants. Hemodynamic conditions during CPT at MDCT and PET were similar (P>0.3). Relative changes in coronary artery surface because of CPT (-2.0-21.2%) correlated to changes in MBF (-0.10-0.52 ml·min -1·g -1) (ρ=0.68, P=0.02). Effective dose was 1.3±0.2 mSv for MDCT and 3.1 mSv for PET/CT. Conclusions: Assessment of endothelium-dependent coronary vasoreactivity using MDCT CPT appears feasible. Because of its wider availability, shorter examination time and similar radiation burden, MDCT could be attractive in clinical research for coronary status assessment.