Reiko Kagawa

Validity of B-Mode Ultrasonographic Findings in Patients Undergoing Carotid Endarterectomy in Comparison With Angiographic and Clinicopathologic Features

BACKGROUND AND PURPOSE Determining factors for performing carotid endarterectomy (CEA) are the severity of carotid stenosis and the presence of plaque ulcerations. Precise detection of these factors is important. The aim of this study was to assess the applicability of using B-mode ultrasonography for diagnosing carotid lesions in patients undergoing CEA. METHODS B-mode examinations were performed on 64 Japanese patients (68 arteries) who subsequently underwent CEA. In each case, the appearance of plaque on B-mode was classified into one of two types: heterogeneous or homogeneous; plaque echogenicity was expressed as hypoechoic, isoechoic, or hyperechoic. Surface characteristics such as ulceration also were examined, and the degree of carotid artery stenosis was calculated. The B-mode findings were compared with angiographic and pathological features. RESULTS B-mode accurately visualized macroscopic ulceration and surface irregularity in 93.8% of the lesions examined, which was superior to angiography. Fifty-four lesions (79.4%) were of the heterogeneous type and 14 lesions (20.6%) were of the homogeneous type on B-mode. Microscopically, 57.4% of the heterogeneous-type lesions demonstrated fibrous change. The frequency of calcification was higher in the heterogeneous lesions than in the homogeneous lesions. CONCLUSION B-mode ultrasonography findings can provide information about macroscopic and microscopic characteristics of carotid lesions.

Traumatic dissection of the common carotid artery after blunt injury to the neck

BACKGROUND Occlusive lesions of the common carotid artery (CCA) resulting from blunt injury are extremely rare, and their clinicopathologic and therapeutic features have not yet been clarified. OBJECTIVES AND RESULTS Five patients with occlusive lesions of the CCA developed neurologic deficits at 1.5 hours to 10 years after blunt neck injury. Lesions included two complete occlusions, one severe stenosis, and two segmental intimal dissections of the CCA. In the two patients with CCA occlusion, bypass surgery was performed using a Dacron graft between the ipsilateral subclavian artery and the carotid bifurcation. In the remaining three patients, the involved segments were replaced with a Dacron graft. Surgical specimens from the early posttraumatic period revealed intimal tears with mural thrombosis and/or subintimal hematomas and those from the later period showed myointimal hyperplasia or fibrotic organization. CONCLUSION Traumatic occlusive lesions of the CCA tend to evolve from intimal dissections to severe stenoses or occlusion, compromising cerebral circulation. The involved CCA can be diagnosed early by B-mode Doppler sonography and successfully reconstructed using a Dacron graft.

Diffusion Anisotropy of Cerebral Ischemia

Focal cerebral ischemia was produced by occlusion of the middle cerebral artery with a silicone cylinder in Wistar rats. Diffusion-weighted echo-planar images (DW-EPIs) using the motion-probing gradient (MPG) method were acquired at 1-3 hours and 24-48 hours after occlusion. Apparent diffusion coefficients (ADCs) were calculated from these images in ischemic lesions and in normal unoccluded regions. Results were as follows. 1. Ischemic lesions could be detected on the DW-EPIs at 1 hour after occlusion. 2. The ADC of water in the brain tissue was smaller than that of free water as a result of restricted diffusion. 3. Anisotropic diffusion that probably can be attributed to the myelin sheath was observed in the normal deep white matter. 4. In the ischemic lesions, the ADC decreased rapidly within 1-3 hours after occlusion and then slightly further declined after 24-48 hours. In the ischemic deep white matter, diffusion anisotropy disappeared at 24-48 hours after occlusion. Diffusion-weighted imaging may have applications in the examination of pathophysiological mechanisms in cerebral ischemia by means of evaluation of ADC and diffusion anisotropy.

B-mode ultrasonographic investigations of morphological changes in endarterectomized carotid artery

BACKGROUND The aim of this study was to assess morphological changes in the endarterectomized carotid region using B-mode ultrasonography (USG). METHODS USG examinations were performed on 54 Japanese patients who underwent carotid endarterectomy (CEA). The endarterectomized regions were periodically investigated and the intima-media thickness (IMT) was measured. RESULTS Postoperative USGs revealed an evident step formation (type I: 20.4%), a gentle slope (type II: 42.6%), or complete smoothness (type III: 37.0%) at the junction of the endarterectomized carotid region and the common carotid artery (CCA). The IMT of the CCA progressively increased from type I to type III. Patients were followed up for an average of 2.7 years. The new intima-media complex (IMC) was confirmed in all cases after 9 months; it was visualized as an isoechoic layer (7%) or a mixture of iso- and hypoechoic layers (93%). Changes in the IMT during the follow-up period were classified into three groups: no change (group I: 23.1%), decrease (group II: 15.4%), and increase (group III: 61.5%). CONCLUSIONS USG is useful to clarify the complicated healing processes of the endarterectomized carotid artery.

Carotid Imaging by Real-time B-mode Doppler in Cerebrovascular Disease

Clinical application of noninvasive imaging of the extracranial carotid arteries was compared using real-time B-time Doppler and angiography (including DSA). Two hundred eighty-nine ultrasonograms (152 patients) were performed. B-mode ultrasonography permitted the identification of several characteristic findings of plaques. There were several types of plaque: (1) homogeneous (2) heterogeneous (3) sonolucent (4) hyperchoic (5) others (skip plaques spotty plaque, etc.) Overall accuracy was 84.3% in 127 carotid arteries. Correlation between B-mode Doppler and angiography is relatively good, but accuracy in complete occlusion and/or severe stenosis was rather low. Even relatively small plaque was apt to be found by B-mode Doppler imaging. The noninvasive ultrasonography examination is very a useful method of evaluating carotid artery disease, especially, in older patients or in postoperative follow-up of carotid surgery.