Background: Even in the era of drug-eluting stents, underexpansion of coronary stents remains a prominent cause of in-stent thrombosis and restenosis in patients having percutaneous coronary interventions (PCI). The aim of this work was to evaluate the value of using stent boost (SB) to detect stent under expansion (UE) by comparing this method to the gold-standard method of measurement by intravascular ultrasound (IVUS). Methods: This prospective observational cross-sectional research enrolled 21 cases with chronic coronary artery disease who had elective PCI with IVUS and SB. Every patient was exposed to full history taking, full clinical examination and echocardiography. Pre-stenting IVUS was done to assess lesion characteristics, vessel measurements specifically distal reference lumen diameter and area (distal RLD, RLA) and to assess the size of the needed stent. SB image was obtained helped by the deflated balloon of the immediately deployed stent. IVUS was introduced post-stenting to obviate any hidden complication as well as to assess stent measurements of minimal stent diameter and area (MSD, MSA), hence, identify the group of patients with stent UE for which subsequent high pressure balloon dilatation was done. Post-procedure off-line processing of SB and QCA images to evaluate the presence of UE by both modalities. Results: SB showed good agreement to IVUS regarding MSD which became optimal agreement when done for Xience Xpedition stent (as the commonly used stent in our study).  SB was able to detect optimal expansion compared to IVUS with 100% sensitivity and 33.33% specificity (p =0.005, AUC=0.808) at cut-off value criteria of MSD/distal RLD of 70%. The specificity increased to 66.67% when the cut-off value criteria of MSD/distal RLD was 76%. There was less agreement between QCA and IVUS. Conclusions: Stent boost showed good agreement to IVUS regarding MSD which became optimal agreement when done for Xience Xpedition stent (as the commonly used stent in our study). SB was able to detect optimal expansion compared to IVUS with 100% sensitivity and Expedition 66.67% specificity (p =0.005, AUC=0.808) at MSD/distal RLD of 76% as a cut-off value criteria.