Contrast-enhanced transcranial color-coded duplex sonography in ischemic cerebrovascular disease.

BACKGROUND AND PURPOSE: Echo contrast agents have been shown to provide conclusive examinations in most patients with insufficient ultrasound penetration through the temporal bone. We investigated the diagnostic value of contrast-enhanced (CE) transcranial color-coded duplex sonography (TCCD) in patients with ischemic cerebrovascular disease and insufficient temporal windows and evaluated TCCD criteria that predict whether CE-TCCD studies may become conclusive. METHODS: Thirty-three patients presenting with ischemic strokes (n = 21) and transient ischemic attacks (n = 12) were investigated. Extracranial color duplex imaging showed normal findings in 24 patients, eight > or = 70% stenoses and one occlusion of the carotid arteries in 8 patients, and severe occlusive disease of both vertebral arteries in 1 patient. Seven carotid stenoses and vertebral artery obstructions were confirmed by angiography. The galactose/palmitic acid-based echo contrast agent was injected intravenously as bolus of 200, 300, or 400 mg/mL in a dosage of 10, 5, and 5 mL, respectively. RESULTS: Thirty-two of the 33 patients were completely examined because 1 patient who felt pain at the injection site declined further investigations. Twenty-one (66%) of 32 CE studies were conclusive and showed cross-flow through three anterior and two posterior communicating arteries, but no stenoses and occlusions. Precontrast identification of any cerebral artery provided an overall accuracy of 97% in predicting a conclusive CE investigation. Precontrast TCCD identified no arterial Doppler signals in patients with inconclusive CE studies. CONCLUSIONS: CE-TCCD provided conclusive examinations in two thirds of patients with ischemic cerebrovascular disease and ultrasound-refractory temporal windows. Precontrast detection of any cerebral artery reliably predicted a conclusive CE investigation.

Ultrasound findings in carotid artery dissection: analysis of 43 patients.

BACKGROUND AND PURPOSE: To analyze the value of ultrasound for early diagnosis and follow-up of internal carotid artery dissection. METHODS: The carotid arteries were evaluated in 43 consecutive patients using extracranial and transcranial pulsed-wave Doppler and duplex sonography. RESULTS: Ultrasound examination was performed, on average, 7.7 days after the first symptoms. The dissections subsequently were verified by MRI (16 patients), angiography (13 patients), or both (14 patients) on average 4.4 days later. The overall sensitivity of the combined examination was 95% (93% for extracranial Doppler, 86% for transcranial Doppler, and 79% for duplex sonography). All three methods detected occlusions or high-grade stenoses in 100% of patients and moderate- or low-grade stenoses in 80% (combined methods), 70% (extracranial Doppler), 40% (transcranial Doppler), and 20% (duplex) of the patients. The findings in 33 patients with an occlusion or high-grade stenosis according to neuroradiology were as follows: absent flow signal in the internal carotid artery (100%) and biphasic (stump) flow in its bulb (86%), high-resistance flow pattern of the ipsilateral common carotid artery (91%), signs of collateral flow across the circle of Willis (97%), and low flow in the middle cerebral artery (79%) on transcranial insonation. In seven patients, a moderate stenosis of the high cervical carotid segment was found because of a retromandibular high-velocity signal. In five of them this was the only abnormal finding. Duplex examination was helpful because it confirmed absent internal carotid artery flow or stump flow in the case of occlusion or high-grade stenosis (100%) and excluded an atherosclerotic origin by demonstrating a patent bulb (100%) and the absence of plaques (95%). Follow-up studies showed recanalization in 63% of patients, occurring at variable intervals. Occlusion persisted in 37%. CONCLUSIONS: Ultrasound performed within the first weeks can corroborate a clinically suspected carotid dissection in up to 95% of patients. Repetitive follow-up studies in most cases are sufficient to monitor evolution.

Ultrasound findings in spontaneous extracranial vertebral artery dissection.

BACKGROUND AND PURPOSE: In this study we analyzed the value of ultrasound examination for diagnosis of vertebral artery dissection. METHODS: The vertebrobasilar arterial system was assessed in 14 patients using transcranial and extracranial pulsed-wave Doppler and duplex sonography. RESULTS: The dissections were verified by angiography (in 1 patient), magnetic resonance imaging (in 5), or both (in 8). The dissected segments were atlantoaxial (V-3) in 6, V-3 and intertransverse (V-2) in 3, V-3 and intracranial (V-4) in 3, and V-2 in 2 patients. Extracranial and transcranial Doppler examination of the atlas loop, involved in 12 patients, showed absent flow signal in 5, low bidirectional flow signal in 1, and poststenotic low blood flow velocities in 3 patients. Seven of these patients had high-grade stenosis or occlusion. The stenotic segment with increased flow signal could be identified directly in 2 patients. Duplex examination of the intertransverse segment confirmed absent flow in 4 patients, making technically insufficient examination unlikely. In the 2 patients with directly detected stenosis, duplex examination showed low flow velocities before the stenosis. The combined use of extracranial and transcranial Doppler and duplex sonography increases the diagnostic yield to detect vertebral artery pathology. If any abnormal sonographic finding was considered, the yield was 86%; relying only on definitively abnormal findings (absent flow signal, severely reduced vertebral artery blood flow velocities, no diastolic flow, bidirectional flow, and a stenosis signal), the yield was 64%. CONCLUSIONS: In most cases, there is no pathognomonic ultrasound finding for vertebral artery dissection. However, if a patient presents with suggestive symptoms, ultrasound may corroborate the clinical suspicion and aid in the decision regarding early anticoagulant treatment. A definite diagnosis can be made noninvasively when magnetic resonance imaging demonstrates hematoma in the vessel wall. Angiography yields additional information such as nature of underlying vascular disease, site and extent of dissection, intracranial extension, and presence of pseudoaneurysm.