Accuracy of quantitative vessel analysis in endovascular treatment for femoropopliteal lesions

Background: Our aim was to evaluate the accuracy of quantitative vessel analysis (QVA) in measuring the reference vessel diameter (RVD) of femoropopliteal lesions. Methods: Between October 2014 and September 2015, 30 consecutive femoropopliteal lesions in 25 patients who underwent endovascular therapy (EVT) under intravascular ultrasound (IVUS) guidance were analyzed. RVDs measured using QVA(sheath) (calibrated using a 6-Fr sheath in the common femoral artery) and QVA(ruler) (calibrated using a ruler on the angiography table) were compared to those obtained using IVUS as the reference values. Results: The mean QVA(sheath)-measured RVD was significantly larger than the mean IVUS-measured RVD (5.34 +/- 1.29 vs. 5.07 +/- 1.20 mm, P=0.001). In contrast, mean QVA(ruler)-measured RVD was 4.60 +/- 1.04 mm, which was significantly smaller than both the mean IVUS- and mean QVA(sheath)-measured RVD (both P<0.001). Bland-Altman analysis revealed that the 95% limits of agreement versus IVUS ranged from -0.94 to 1.49 mm for QVA(sheath) and -1.69 to 0.76 mm for QVA(ruler), respectively. Agreement with tolerance of +/- 1.00 mm accounted for 88% of QVA(sheath) and 83% of QVA(ruler) (P=0.60). The difference between QVA- and IVUS-measured RVDs was inversely correlated with the distance from the table (P=0.029 for QVA(sheath) and P=0.003 for QVA(ruler)). Conclusions: The accuracy of both QVA(sheath) and QVA(ruler) in measuring RVD were similarly suboptimal. Over- and under-estimation of RVD is not rare in QVA.