2008 Volume 17 Issue 12 Pages 917-923
The technologies for the diagnosis of unstable plaque in the carotid artery are developing and the imaging modalities are also increasing. However, the evidence levels are not so high. Some reports suggest that the ultrasound findings of low echoic plaque, ulcer formation and heterogeneous plaque are the signs of vulnerable plaque. Recently, I have found that some types of plaque have mobility on part of the plaque surface. I call such plaque "mobile plaque". I believe that after comparison with the pathological specimens, this finding reflects a rupture of the plaque and fresh intra-plaque hemorrhage. Especially, symptomatic patients with this condition tend to suffer relapse strokes, so rapid action is needed to prevent it from worsening. Detection of the micro-embolic signals by trans-cranial Doppler method can evaluate the vulnerability of carotid artery plaque indirectly, because micro-embolic signals reflect any attached fragile thrombus on the plaque or plaque rupture. Stroke patients with a lot of micro-embolic signals need careful treatment, because these patients also tend to relapse. Plaque imaging by MRI is a useful method to evaluate vulnerability of the carotid artery plaque. I think combined MRI and ultrasound examinations can cover any weaknesses in either system alone. Now, there is no established guideline for the diagnosis of unstable plaque, so it is necessary to match-up modalities according to need.
