The effect of calcium-associated acoustic shadowing on Virtual Histology intravascular ultrasound (VH-IVUS) plaque component analysis is unknown. Methods. We harvested 92 coronary arteries from 32 autopsied specimens. IVUS imaging was performed 50mm from the LMCA ostium. We then selected 12 calcified segments for comparative VH-IVUS vs pathologic comparisons. Results. Pt age was 46짹8.9yrs and 90% were males. VH-IVUS analysis of the calcified plaque showed 11짹3.8% necrotic core, 8짹1.9% fibrofatty plaque, 69짹9.9% fibrotic plaque, and 10짹6.6% dense calcium. Dense calcium was correlated with the size of the necrotic core (r=0.774, p=0.009). VH-IVUS analysis showed fibrotic tissue behind the calcium, but histopathology showed an acellular sclerotic area (dense collagenous tissue) just beneath the calcium with a relatively well-preserved vascular smooth muscle layer. Within the necrotic core, VH-IVUS showed prominent red necrotic core area combined with calcium; however, histopathology showed empty space of decalcification surrounded by just collagenous tissue with outer smooth muscle actin positive cell layer. More importantly, no active inflammation was present around calcium. Conclusion. VH-IVUS necrotic core surrounding areas of dense calcium correlated with dense collagenous tissue histopathologically. It is important not to overinterpret VH IVUS studies of dense calcium with prominent necrotic core. More precise classification/validation for necrotic core is necessary.