Assessment of optimum stent deployment by stent boost imaging: comparison with intravascular ultrasound

Stent boost (SB) imaging is an enhancement of the radiologic edge of the stent by digital management of regular X-ray images. The purpose of the present study was to validate SB imaging by comparison with the anatomical standard using intravascular ultrasound (IVUS). We investigated SB and IVUS after stent implantation in 68 arteries in 60 patients. Based on those findings, we added high-pressure dilatation in four patients and another stent implantation in four patients. We defined the SB criteria for adequate stent deployment as: complete stent expansion, stent minimum diameter ≥70% of reference diameter, and stent minimum diameter ≥2.0 mm; and IVUS criteria for adequate stent deployment as: minimal stent area ≥5.0 mm(2). If the reference vessel was <2.8 mm, adequate stent deployment was defined as minimum stent area ≥4.5 mm(2). IVUS findings indicated inadequate stent deployment in 21/72 observations (29%). Seven SB images showed inadequate stent expansion. SB predicted inadequate findings of IVUS with 100% specificity, 33% sensitivity, and 81% agreement. Although the sensitivity of SB image for adequate stent deployment is low, the specificity is sufficiently high for it to be the first-line for monitoring just after stent implantation in centers where IVUS is not used routinely.