Objectives: To compare intra-coronary near-infrared spectroscopy (NIRS) and optical coherence tomography (OCT) for the detection of lipid, also to identify NIRS signals to differentiate superficial lipid, and to characterize the plaque with yellow block chemograms on NIRS. Background: Intra-coronary NIRS has been developed to detect lipid core plaque (LCP). Methods: We investigated a total of 17 patients who underwent both OCT and NIRS. NIRS analysis included plaque lipid core burden index (LCBI), LCP length, and the presence of yellow block (YB) on the block chemogram. OCT analysis included maximum lipid arc (LA), the length of lipid (LL), lipid index, and ...