Since the introduction of coronary angiography in 1959,' a new "gold standard" examination became avail-able for the evaluation of coronary artery disease. The tra-ditional approach for transcatheter coronary revasculariza-tion since the introduction of percutaneous transluminal coronary balloon angioplasty (PTCA) by Gruentzig in September 1977 had been visual assessment of the lesion as well as the results of the intervention by coronary an-giography ." Refinements in the technology and techniques for mechanical revascularization in the 1980s lead to ex-plosion of " new devices mainly in an attempt to attenuate the major limitation of PTCA related restenosis. Various pharmacological agents have shown promising results in reducing the rate of restenosis, including monoclonal anti-bodies against the glycoprotein receptors on platelet cell surfaces." Yet restenosis continues to be the "Achilles heel" of transcatheter interventions. Restenosis occurs in 30% to 50% of transcatheter coronary procedures. The natural history and pathophysiology of restenosis are still incompletely understood.4 Certain clinical, angiographic and procedure-related variables have been identified as risk factors for restenosis.5'6 Coronary stenting, especial-ly the recent development of drug-eluting stents has been proven to be effective to prevent restenosis to some ex-tent. Restenosis remains still exist. Recent studies have shown that assessment of the lesion length using intravas-cular ultrasound (IVUS) in order to fully cover the lesion for a drug-eluting stent is of clinical importance.