Background Main pulmonary artery diameter (mPA) and ratio of mPA to ascending aorta diameter (ratio PA) derived from chest CT are commonly reported in clinical practice. We determined the age and sex-specific distribution and normal reference values for mPA and ratio PA by CT in an asymptomatic community-based population. Methods and Results In 3171 men and women (mean age 51 ± 10 years, 51% men) from the Framingham Heart Study, a non-contrast ECG gated eight-slice cardiac multi-detector CT was performed. We measured the mPA and transverse axial diameter of the ascending aorta at the level of the bifurcation of the right pulmonary artery and calculated the ratio PA. We defined the healthy referent cohort (n=706) as those without obesity, hypertension, current and past smokers, chronic obstructive pulmonary disease, history of pulmonary embolism, diabetics, cardiovascular disease, and heart valvular surgery. The mean mPA diameter in the overall cohort was 25.1 ± 2.8mm and mean ratio PA was 0.77 ± 0.09. The sex-specific 90th percentile cutoff value for mPA diameter was 28.9 mm in men and 26.9 mm in women and was associated with increase risk for self-reported dyspnea (adjusted odds ratio 1.31, p=0.02). The 90th percentile cutoff value for ratio PA of the healthy referent group was 0.91, similar between gender, but decreased with increasing age (range 0.82 to 0.94), though not associated with dyspnea. Conclusions For simplicity, we established 29 mm in men and 27 mm in women as sex-specific normative reference values for mPA and 0.9 for ratio PA.

Adenosine stress CT can identify stress-induced myocardial perfusion defects with diagnostic accuracy comparable to SPECT, with similar radiation dose and with the advantage of providing information on coronary stenosis.