IVUS is still alive - multi parameter analysis for tissue characterization of coronary atherosclerosis and interpretation from acoustic microscopy observation

Is IVUS still alive in the era of OCT which provides higher resolution imaging? Besides easier usability, IVUS is superior to OCT from the point of view of tissue characterization of coronary atherosclerosis. In the present study, multi parameter analysis such as integrated backscatter (IB), Virtual Histology (VH), strain rate imaging and newly developed method named “attenuation imaging” are compared and discussed the interpretation by acoustic microscopy observations. RF signal was obtained from commercial available IVUS systems by the use of fast digitizer card with the sampling frequency of 400 MHz. IB-IVUS image was generated by integrating 128 points of absolute value of RF signal. Conventional IVUS and IB-IVUS show homogeneous fibrous plaque but the deeper region is represented as fibrofatty plaque by VH-IVUS, softer region in the strain rate imaging and low attenuation in the attenuation imaging. Acoustic microscopy observation showed the fibrofatty region as lower attenuation than that of the fibrous tissue. Multi parameter analysis showed the region of soft plaque more clearly than conventional IVUS. As ultrasound reflects mechanical properties of the tissue, IVUS provides important information which was not provided by OCT.