OBJECTIVETo demonstrate the abnormal intima rotation pattern of the carotid atherosclerosis plaque using velocity vector imaging, and to develop a new method for the clinical mechanical state assessment of the plaque intima.

METHODSThe rotation movement and rotation angle on the serial dynamic ultrasonic short-axis gray scale views of 48 isolated atherosclerosis plaques (i. e., upstream, midstream, and downstream) and nearby reference segments of carotid artery in 46 patients were derived and analyzed using a dedicated velocity vector imaging workstation. The incidence of intima rotation movement and the rotation angle at different sections of the plaque and nearby reference segments before and after the standard grip stress test during systole and diastole respectively were counted and measured.

RESULTSBefore and after the stress test, the intima rotation movement occurred at the majority of the short-axis sections of the plaque and the nearby reference segments during cardiac cycle. Before the stress test, the incidence of intima rotation movement at the upstream section of the plaque during systole was significantly higher than that of reference segment (P = 0.036) The reversal direction of the intima rotation at those sections and reference segment during systole and diastole was demonstrated. After the stress test, the incidence of intima rotation movement at the midstream section of the plaque during diastole was significantly lower than that of reference segment (P = 0.031). The incidence of the intima rotation movement changed at the sections of upstream, midstream, and downstream of the plaque before and after the stress test also were explored (i. e., increased in systole and decreased in diastole) except the reference segment intima.

CONCLUSIONSThe intima rotation movement occurs at the majority of the isolated plaque and nearby reference segment, and the incidences of the intima rotation movement at the plaque is different from that of the reference segment during systole and diastole respectively. The abnormal pattern of intima rotation movement may be used to indicate the unstable mechanical state of the isolated plaque intima.