This is a retrospective, single-center study to develop and validate an updated algorithm for computing fractional flow reserve from intravascular ultrasound images (IvusFFR v2.0). The study will use existing intravascular ultrasound (IVUS) images and corresponding invasive fractional flow reserve (FFR) measurements obtained from approximately 100 patients who underwent clinically indicated coronary angiography, IVUS, and FFR assessment at Fuwai Hospital. All data will be anonymized prior to analysis. The primary objective is to assess the diagnostic accuracy of IvusFFR v2.0 in identifying hemodynamically significant coronary stenosis, using wire-based FFR ≤0.80 as the reference standard. This study involves no prospective intervention or additional patient contact.