Background: iMAP is a new intravascular ultrasound (IVUS) derived technique for tissue characterization using spectral analysis. Since there is a need for reproducibility data to design longitudinal studies, we sought to assess the in vivo reproducibility of this imaging technique.
Methods: iMAP (40 MHz, Boston Scientific Corporation) was performed in patients referred for elective percutaneous intervention and in whom a nonintervened vessel was judged suitable for a safe IVUS analysis. Overall 20 patients with 20 non-angiographically significant lesions were assessed by two independent observers. Five of these 20 patients received an additional iMAP analysis using a new IVUS catheter and using the same catheter after its engagement and reengagement.
Results: The interobserver relative difference in plaque area was 2.5%. Limits of agreement for lumen, vessel, and plaque area measurements were 1.62, -2.47 mm(2) ; 2.09, -3.71 mm(2) ; 2.80, -3.72 mm(2) ; respectively. Limits of agreement for fibrotic, lipidic, necrotic, and calcified measurements were 1.32, -1.44 mm(2) ; 0.24, -0.36 mm(2) ; 1.50, -2.26 mm(2) ; 0.09, -0.11 mm(2) ; respectively. The intercatheter and intracatheter relative difference in plaque area were 0.9% and 4.1%, respectively. Although the variability for compositional measurements increased using two different catheters or using the same catheter twice, the variability for compositional measurements keeps always below 10%.
Conclusions: Our analysis demonstrates that the geometrical and compositional iMAP analysis is acceptably reproducible.
Keywords: angiography; coronary; intravascular ultrasound; lipids.
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