The accuracy of length measurements using different intravascular ultrasound motorized transducer pullback systems

Accurate length measurements by intravascular ultrasound (IVUS) are necessary for stent length selection and for IVUS volumetric analysis. The comparative accuracy of commercially available transducer pullback systems--a necessity for accurate IVUS length and volume measurements--has never been studied. We evaluated the accuracy of four IVUS pullback systems by studying 180 patients (45 in each group) who had been treated with a single stent of known length. Stented lesions were located in the left anterior descending artery (n = 77), left circumflex artery (n = 41), right coronary artery (n = 41), left main (n = 2), and saphenous vein grafts (n = 19). The known lengths of implanted stents ranged from 8 to 33 mm. The correlations between known stent length and IVUS-measured stent length in each group were 0.92 for CVIS, 0.83 for BSC Galaxy, 0.63 for Endosonics TrackBack, and 0.69 for Volcano Model R-l00 research pullback device, respectively. Furthermore, the absolute value of the difference between the two measurements was 9.1 +/- 13.1%, 8.8 +/- 10.2%, 18.6 +/- 21.5%, and 17.5 +/- 31.4%, respectively. With the Volcano Model R-l00 research pullback device, there were 3 extreme outliers; if these three outliers were excluded, then the correlation improved from 0.69 to 0.91; and the absolute deviation from known stent length improved from 17.5 +/- 31.4% to 9.7 +/- 8.3%. Thus, there is a significant variation in length measurement accuracy among IVUS pullback devices. This should be taken into account both clinically and when planning scientific studies.