Reproducibility of neointima quantification with motorized intravascular ultrasound pullback in stented coronary arteries

Background Intravascular ultrasound (IVUS) imaging has shown excellent repr oducibility immediately after coronary stent implantation. However, the var iability of measurements in lesions late after stent implantation, when neo intima formation is present, has not been studied. Neointimal tissue is gen erally tow echogenic and thus difficult to quantify. We therefore sought to analyze the reproducibility of morphometric measurements late after stent implantation. Methods and Results Fifty consecutive patients were investigated 6 months a fter Patmaz-Schatz stent implantation (motorized catheter pullback 0.5 mm/s ). Two experienced investigators independently identified the stent area, l umen area, and neointimal area at different sites within the stent. Planime tric measurements were performed with commercially available software. Corr elation coefficient and mean difference for corresponding measurements were calculated for the intraobserver and interobserver comparisons. Variabilit y for the intraobserver and interobserver comparisons was similar. Observer agreement regarding the presence of neointimal hyperplasia was as high as 71% (interobserver comparison 62%). The mean difference for neointima area was 0.06 +/- 1.5 mm(2) (-0.6 +/- 1.5 mm(2)); mean differences for lumen are a were 0.02 +/- 0.1.9 mm(2) (0.03 +/- 0.17 mm(2)) and for stent area 0.01 /- 0.09 mm(2) (-0.02 +/- 0.12 mm(2)) (values for interobserver comparison a re given in parentheses), Correlation between measurements was high for all structures: correlation coefficients were 0.66 (0.69) for neointima, 0.94 (0.95) for lumen, and 0.95 (0.91) for stent area. Conclusions Morphometric measurements of IVUS investigations with motorized IVUS pullback late after stent placement show good reproducibility, Intrao bserver variability and interobserver variability are low. Differences for corresponding measurements were more pronounced for neointima area. Motoriz ed catheter pullback guarantees high reliability of IVUS measurements and s hould be used routinely for clinical IVUS studies.