Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Comparative Study
Power Doppler compared to color-coded duplex sonography in the assessment of the basal cerebral circulation.
Power-based transcranial duplex sonography (p-TDS) is a new promising ultrasound technique that generates intravascular color signals from the amplitude of the echo signal. The present investigation was undertaken to determine the advantages and limitations of power Doppler in the assessment of the basal cerebral circulation compared with transcranial color-coded real-time sonography (TCCS) and contrast-enhanced transcranial color-coded real-time sonography (CE-TCCS). Thirty-eight patients without cerebrovascular diseases were examined with p-TDS and TCCS, and in 11 patients CE-TCCS studies were performed. ⋯ In comparison with CE-TCCS, p-TDS had no important advantages in the detection of intracranial vessels. In conclusion, p-TDS and CE-TCCS were superior to TCCS with regard to identification of the basal arterial circulation. Both methods permit noninvasive and reliable identification of the basal cerebral circulation.
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Comparative Study
Transcranial Doppler in 178 patients before, during, and after carotid endarterectomy.
From July 1991 to March 1995, 178 patients who underwent 198 carotid surgical repairs were investigated preoperatively, intraoperatively, and postoperatively by transcranial Doppler sonography (TCD). Preoperative TCD evaluation showed stenosis of the middle cerebral artery (MCA) in 4 patients (2.2%), siphon stenosis in 3 (1.6%), incomplete circle of Willis in 23 (12.9%), a decrease of mean blood flow velocity more than 70% of the basal value during digital common carotid compression in 31 (17.9%), and a critical reduction of vasomotor reactivity (no significant increase of mean blood flow velocity in the MCA during breath-holding test) in 34 (19.1%). Nine patients (5%) had surgery without preoperative angiography. ⋯ Intraoperative TCD monitoring showed a decrease of mean blood flow velocity in the MCA due to shunt malfunction in (8.3%) of 36 surgeries, turbulence of blood flow during declamping in 79 procedures (39.8%), and microembolic events in 10 patients (5%) that were related to one transient and one permanent neurological deficit. Another permanent deficit occurred in a patient without TCD signs. After surgery, TCD reliably detected an early asymptomatic occlusion of the carotid artery, hyperperfusion syndrome in 12 (6.0%), and an increase of vasomotor reactivity in 10 (29.4%) of 34 surgeries.
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High-intensity transient signals on transcranial Doppler sonography (TCD) are associated with atherosclerotic stenosis of the internal carotid artery. Few data exist regarding the detection of high-intensity transient signals in dissected carotid arteries. In the present study, 6 patients with spontaneous carotid dissection, defined by magnetic resonance techniques and duplex sonography, were examined by TCD. ⋯ No microemboli were found contralateral to the dissected arteries. Microemboli can be detected distally from dissected carotid arteries. The present findings support the assumption that embolism is a major cause of stroke in patients with carotid dissection, and suggest that high-intensity transient signals are more common among patients with cerebral ischemia secondary to dissection.