Introduction an Aim. The ultrasound assessment of flow-mediated dilation (FMD) of the brachial artery is a non-invasive and reproducible technique to evaluate the endothelial function. FMD is classically expressed as a percentage rise of the change in diameter from the baseline after ischemia or administration of sublingual nitroglycerin (NTG).

We compared FMD and internal diameter measurements obtained with an echotracking system (ART.LAB; Esaote BV, Maastricht, the Netherlands), to those obtained with a new, image-based, system for real time measurement of FMD (FMD Studio, Pisa, Italy).

Methods: FMD studio-ART.LAB mean difference of FMD after ischemia and internal brachial diameter at baseline, peak and post-ischemia were tested in 30 subject. Moreover, in a subgroup of 16 subjects, we measured FMD after NTG administration. All measurements were performed simultaneously by ART.LAB and FMD studio.

Results: Mean difference of internal diameter was 0.27±0.24 mm at baseline (7% of mean value), 0.33±0.25 mm at peak (8% of mean value), and 0.30±0.23 mm after ischemia (8% of mean value); mean difference of FMD after ischemia was 0.89±3.97%, corresponding to 15% of mean value. Mean difference of FMD post-NTG was 0.85±4.85%, (5% of mean value). All the values obtained by FMD studio were not significantly different (P=NS) to those obtained by ART.LAB.

Conclusions: We reported a good agreement of FMD and internal diameter measurements between an echotracking device, which represents the gold standard for arterial parameters measurements, and a new, image-based, system for real time measurement of FMD.