Intraoperative ultrasonography is a handy. real-time and cost-effective method for evaluation of tumors. We have examined 53 brain tumors during surgery using power Doppler ultrasonography (7.5-MHz sector scanner. ALOKA)with a contrast agent (Levovist®). Blood flows inside and around the tumor are clearly visualized with power Doppler mode. By increasing the flow signals. a contrast agent is useful for evaluating the vascularity of a tumor and the location of surrounding vessels. The grade of flow signals in a tumor was well correlated with the vascularity assessed with digital subtraction angiography (p = 0.0004). Therefore, intraoperative power Doppler ultrasonography with a contrast agent provides informative data for safe and accurate surgery. especially in cases of hypervascular tumor such as hemangioblastoma. In conclusion. intraoperative power Doppler ultrasonography is useful for resection of tumors. If used in combination with navigation systems. ultrasonography can be replaced by inlraoperative angiography and MRI.
Objective : To ensure the safety of CAS (carotid artery stenting), it is important to clarify the characteristics of the plaque before starting the procedure. and also the characteristics of restenotic lesions occurring in the long-term. We therefore analyzed the suitability and efficacy of virtual histology rvus (VH-IVUS)for assessment of carotid plaque before CAS and follow-up after CAS. Methods : A Volcano Eagle Eye Gold IVUS catheter and the Volcano IVG3 Oracle Imaging System were used. We performed pre-CAS VH-IVUS in 20 cases and follow-up VH-IUVS in 15 cases. Results : The results of evaluation by VH-IVUS were proven to be effective, and although the technique is invasive, it yields adequate information on plaque composition (accurately diagnosing calcified and fibro-lipidic tissue)by color mapping, as well as offering excellent reproducibility and objectivity. Also, the ratio of each component in the entire lesion was quantitatively appreciable. We found that the amount of debris tended to be minimal when the fibrous component accounted for 60% or more of the entire plaque. By follow-up VH-IVUS, we found that the lesions were of a fibrotic neo-intimal hyperplastic nature, suggesting that lesions containing a large fibro-fatty component have an increased risk for progression to restenosis. Conclusions : VH-IVUS that yields highly reproducible and objective results is an effective diagnostic method that helps to anticipate stenotic progression by providing information on the characteristics of the lesions at post:-:CAS follow-up.
We investigated the correlation between mean flow velocity (MFV) in the middle cerebral artery (MCA) detected by transcranial Doppler (TCD) during carotid artery stenting (CAS) and the cerebral blood flow (CBF) ratio of the MCA territory measured immediately after CAS in 23 patients. Cases with contralateral internal carotid artery occlusion and >80% stenosis were excluded. MFV ratio was defined as post-CAS MFV/pre-CAS MFV detected by continuous TCD. CBF ratio was defined as affected CBF of MCA/contralateral CBF of MCA detected by post-CAS xenon-computed tomography. MFV ratio was 1.36 ± 0.46, and CBF ratio was 1.13 ± 0.15. MFV ratio was significantly correlated with CBF ratio (r = 0.84, p<0.0001) .MFV ratio detected by continuous TCD during the CAS procedure may be a predictor of postoperative hyperperfusion.
Since the surveys of the NASCET, ECST and ACAS, it has been debatable whether the carotid artery stenosis rate should be evaluated or not. The stenosis rate in patients is usually checked through angiography in limited orentations, and therefore some data may be lacking. Harmonic imaging is a contrast-specific imaging modality that can exploit the nonlinear properties of ultrasound contrast agents by transmitting at the fundamental frequency and receiving at multiples of these frequencies. Pulse inversion harmonic imaging (PIHI), using pulse inversion to eliminate and strengthen the harmonic frequency, is more effective than conventional harmonic imaging. It is possible to detect tissue perfusion by contrast sonographic imaging with PIHI, and its clinical application has already been reported, for example in myocardial infarction. liver tumor, brain tumor and cerebrovascular diseases. The importance of carotid artery wall characteristics is now acknowledged. and this is largely studied using ultrasonography. Ulceration, surface condition and the sonographic intensity of plaque can be examined, although we are now focusing on the detection of neovascularization in plaque using contrast sonographic imaging with PIHI. Plaque neovascularization is one of the pathological factors responsible for plaque hemorrhage and rupture, and is suggested to be involved in carotid artery stenosis. occlusion and artery-to-artery embolism. There are several routes of vascular wall feeding. One is diffusion through the endothelium and the other is the vasa vasorum from the adventitious to the outer part of the media. Therefore there is no neovascularization on the inner side of the carotid artery. However, as some plaques show neovascularization within them. we have tried to detect them by intermittent and real time contrast sonographic imaging with PIHI. We have already reported the evaluation of neovascularization by the intermittent method and classified it as type l to type IV according to the distribution of the neovasculature in the plaque. Real-time contrast sonographic imaging with PIHI has revealed some characteristics of neovascularization, as follows. 1.The neovascular vessels from the adventitia are larger than those from the endothelium. 2. There is some anastomosis between the neovascular vessels. 3. The distribution of neovascular vessels is predominant in the inner part of the plaque, an in addition, they show a spiral course. 4. The neovascular circulation is related to the pulsation of the carotid artery. 5. Many neovascular vessels originate from the endothelium. Neovascularization can also be observed by real-time 3D CAWP using a matrix array.
Background : Two-dimensional echo imaging is generally used for diagnosis or screening of carotid artery lesions. We evaluated the usefulness and problems associated with a new 4-dimensional ultrasound system (Voluson 730 Expert) for patients with carotid artery stenosis. Patients and Methods : The subjects comprised 160 patients with carotid artery stenosis who underwent 4-dimensional ultrasonography of carotid artery lesions. The system automatically constructs 3-dimensional images from multi-slice image information obtained by a 4-dimensional probe. About 10 s is usually required for automatic scanning. Results : Static and real-time 3-dimensional images obtained using this system showed the total structure of carotid lesions. Distributions of carotid plaque, localization of ulceration, moving plaque or pulsations of the carotid wall were demonstrated more accurately in comparison with 2-dimensional imaging. Static 3-dimensional flow imaging was also used to detect stenosis or ulceration. Real-time 3-dimensional imaging enabled dynamic evaluation of pathology. It may be possible to reduce the duration of echo imaging using this system to screen patients with suspected carotid lesions. Conclusion : Four-dimensional ultrasonography is useful for accurate diagnosis of patients with carotid stenosis by 3-dimensional demonstration of carotid lesions.