[Carotid artery wall perfusion of the plaque: three dimensional contrast sonographic imaging]

We usually check stenosis rate in patients through the limited directions of angiography. This can result in insufficient evaluation. The importance of the condition of the carotid artery wall in fully accpted nowadays, and ultrasound sonography is being used as a means to study it. Neovascularization in the plaque is one of the pathological factors inducing plaque hemorrhage and rupture, and this is suspected of causing carotid artery stenosis, occlusion and artery-to-artery embolism. Harmonic image is a contrast specific imaging modality, which uses the nonlinear properties of ultrasound contrast agents by transmitting at the fundamental frequency and receiving at multiples of these frequencies. Pulse inversion harmonic image (PIHI), using pulse inversion to eliminate and strengthen the harmonic frequency, is more effective than conventional harmonic imaging. We can detect tissue perfusion by contrast sonographic imaging with PIHI. The routes of vascular wall feeding are as follows: One is diffusion through the endothelium and the other is through the vasa vasorum to the outer part of the medium. So there is no neovascularization at the inner side of the carotid artery. But some plaques have neovascularization in themselves, so we have tried to detect them by the intermittent and real time contrast sonographic imaging method with PIHI. We have already reported the evaluation of neovascularization by the intermittent method and classified from type I to type IV according to the distribution of neovascular vessels in the plaque. The real time contrast sonographic imaging method with PIHI has revealed some characters of neovascularization. Furthermore NV was observed through the real time 3D CAWP by matrix array, though there are some problem for the clinical application.