Ultrafast power Doppler imaging for RV myocardial perfusion assessment: histopathologic correlation and in vivo comparison-a pilot study.

AIMS: Myocardial vascular remodeling is a key feature in various diseases associated with right ventricular (RV) pressure overload but its non-invasive assessment remains challenging. The new technique attenuation-compensated fractional moving blood volume (acFMBV) based on ultrafast power Doppler (UPD) was developed for myocardial blood volume quantification, linked to RV remodeling and capillary density, but not validated in vivo.

OBJECTIVES

To quantify RV myocardial blood volume across the cardiac cycle using UPD in rodent models, with histopathological validation, and assess its feasibility in human patients.

METHODS AND

RESULTS

Twelve rats (sex ratio 1/1) were randomized to pulmonary artery banding (PAB) (n = 6) or sham controls (n = 6). After 6 weeks, UPD-derived acFMBV was measured in the RV lateral wall, representing myocardial blood volume. Capillary density was quantified via CD31 immunostaining, and its correlation with mid-diastolic acFMBV was evaluated. UPD was also applied in seven healthy human volunteers and seven age-matched patients with RV pressure overload. Mid-diastolic acFMBV in PAB rats was significantly lower than in controls (5.3% ± 0.9% vs. 7.8% ± 1.2%, P < 0.05), correlating with reduced capillary density (r = 0.78, P < 0.01). In humans, mid-diastolic acFMBV was also lower in RV pressure overload patients compared with healthy volunteers (4.8% ± 0.7% vs. 3.1% ± 2.3%, respectively, P = 0.03).

CONCLUSION

In this pilot study, UPD-based acFMBV correlates with histological capillary density, supporting its potential as a reliable, non-invasive tool for quantifying RV myocardial blood volume in clinical settings. These observations will need to be confirmed in studies with larger sample sizes.

CONDENSED ABSTRACT: Myocardial vascular remodeling in right ventricle (RV) pressure overload is difficult to assess non-invasively. This study validated attenuation-compensated fractional moving blood volume (acFMBV) using ultrafast power Doppler (UPD) to quantify RV myocardial blood volume. Twelve rats underwent pulmonary artery banding (PAB) or sham surgery, with acFMBV measured and correlated with capillary density. PAB rats had lower mid-diastolic acFMBV and capillary density (r = 0.78, P < 0.01). In humans, RV pressure-overload patients showed reduced acFMBV compared with healthy volunteers (P = 0.03). UPD-based acFMBV correlates with histology, supporting its use as a non-invasive tool for assessing RV perfusion.