To examine the effects of risk factors for arteriosclerosis on cerebral vasculature, 1) we performed transcranial Doppler sonography (TCD) in patients with different stages of hypertension and 2) compared the TCD measurements with cerebral hemodynamics determined by positron emission tomography (PET) . 1) Sixteen chronic hypertensives with chronic and small brain infarction, 10 young early-stage hypertensives and 16 young normotensive volunteers were studied. We measured mean blood flow velocity, Gosling's pulsatility index (PI), Fourier PI1 (Fourier PI of the first harmonic) and cerebrovascular resistance of the middle cerebral artery (MCA) . The early-stage hypertensives demonstrated higher velocity, normal Fourier PI1and near normal resistance, whereas the chronic hypertensives showed near normal velocity, higher Fourier PI1 and greater resistance. Results may indicate the difference in severity of cerebral arteriopathy between the early and late stages of hypertension. 2) In 19 patients with brain infarction, hypertension and/or diabetes mellitus, blood flow velocity and CO2vasomotor response (VMR) of the MCA were measured by TCD and compared with the PET parameters. Blood flow velocity and cerebral blood flow (CBF) were significantly correlated in the MCA territory. CO2VMR was more closely correlated with the ratio of CBF to cerebral blood volume, indicating brain perfusion pressure, in each region.
Purpose We used TC-CFI to delineate the abnormal blood flow in the middle cerebral artery (MCA), a segment of which had been found by TCD to be associated with an abnormal blood flow velocity. Our purpose was to find whether or not the procedure is useful in excluding false positive sign. Method The subjects were assigned to one of the following two groups: a high velocity group-those who had a maximum systolic flow velocity in the MCA (determined by TCD) that exceeded the mean +2 SD of the normal controls (126 cm/s) ; and a low velocity group-those with a velocity below the mean -2SD (52 cm/s) . In both group, the segmental image of the MCA (where a high or low flow velocity was recorded by TCD) was studied by TC-CFI to elucidate the cause of the flow abnormalities. Results and Conclusion 1. The stenotic lesion was easily detected with TC-CFI, because the flow signal changed from red to yellow or a mosaic pattern. The section where the maximum systolic flow velocity (determined after angle correction) exceeded 170 cm/s is indeed stenotic. 2. Two explanations are offered for the segment that showed a low flow velocity by TCD: the actual flow velocity was also low; and the existence of a so-called false-positive phenomenon (i.e., the corrected flow velocity is normal because the angle between the MCA and the Doppler beam is large) . 3. TC-CFI is very useful in elucidating the relationship between the Doppler beam and the flow through the MCA.
We measured flow velocities of the basilar artery (BA) via the suboccipital window by TCD in 115 subjects to investigate BA hemodynamics. Twenty one of the subjects had posterior circulation pathology, 37 had anterior circulation pathology, and the remaining 57 cases had no lesions. The vascular lesion was confirmed by cerebral angiography in all cases. The characteristic findings of the BA flow velocity by the site of vascular lesion were as follows. 1) Normal: signal obtainable from a depth of 80 mm to depths beyond 95 mm. Timeaveraged mean velocity was between 20 and 45 cm/s and velocity variations occurred at different depths<16 cm/s. 2) BA occlusion: a) Total occlusion: no signal or signal only from the site adjacent to the vertebrobasilar junction. b) Distal occlusion: continuous low velocity (<20 cm/s) .c) Proximal occlusion: continuous retrograde flow. 3) Stenosis of the BA: sudden increase in flow velocity at the stenotic portion or continuous low velocity proximal to the site of severe stenosis. 4) Occlusion of the bilateral vertebral arteries (VA) : flow from the anterior spinal artery detectable. 5) Unilateral occlusion of the VA: no distinctive flow pattern. 6) Internal carotid artery occlusion or vascular rich tumor in the posterior lobe: increased flow velocity along the BA. 7) Other anterior circulation pathology: no characteristic signal.
Recently, several authors have reported the character of embolic signals in TCD (transcranial Doppler sonography) as follows: (1) high intensity signals (3-60 dB) greater than the background Doppler spectrum; (2) random occurrence within the cardiac cycle; (3) transient appearance and short duration; (4) bell-shaped signals focused on a small band of frequencies within the Doppler spectrum; (5) harmonic sound quality; (6) monitoring time of over 30 minutes; required and (7) signals must be differentiated from artifacts. We studiedthe detectability of embolic signals using a Doppler recording system. Embolic signals of the middle cerebralartery were monitored by TCD using an experimental animal model and 3 patients with epilepsy or brain tumor who underwent cerebral angiography by the Seldinger method. In the animal model, artificial air emboli were easily detected as short-term and hyper-intense ultrasonic signals, while thrombotic emboli were not identified definitely. Furthermore, our clinical cases suggested that microscopic air emboli at the site of injection of the contrast medium may be prevented by slow washout with saline. We propose new criteria for embolic signals.
BACKGROUND AND PURPOSE: Recent striking introduction of transcranial color flow image (TC-CFI) in Doppler ultrasonography by Furuhata and Spencer has made it possible to investigate and appreciate intracranial hemodynamics more clearly in a clinical situation. The TC-CFI illustrates the blood flow velocity pattern as well as the exact observation angle at a fixed point of the vessel under examination. This minimizes technical errors in the hemodynamic measurements by making mathematical corrections of the data measured. Another advantage is that sourced data can be compared temporary in a clinical course at a fixed point of the vessel. We attemped to scan some AVMs and aneurysms. METHODS: ATL made ULTRAMARK 9 (2.25 MHz) (sample volume from 1.5 to 3.0mm×1.0mm) . RESULTS: AVMs were diagnosed presumptively by X-ray CT scaning and MRI in 10 patients. TC-CFI was performed in these cases prior to angiography. Nidus was roughly outlined in 7 cases. TC-CFI demonstrated an irregularly congregated mass of blue, yellow and red color, suggesting conplicated a mixture of small and large vessels. Doppler frequency sonogram in the nidus demonstrated a complicated pattern. It seemed to be mixture of artery, vein and turbulent flow and peak velocity was 160 cm/s. After partial embolization, a new vascular image was demonstrated, which was also seen in digital subtractionangiography. The Doppler frequency sonogram dropped to 100 cm/s. The final frequency sonogram was 60 cm/s when we terminated embolization. CONCLUSION: TC-CFI scanning allowed evaluation of the complete timing of endovascular surgery.
Intra- and extra cranial hemodynamics and vascular reactivity were studied with transcranial Doppler ultrasound (TC2-64B) in patients with Moyamoya disease and the criteria for diagnosis were proposed. Studies were conducted in 15 normal subjects and 15 patients with angiographically proven Moyamoya disease. In 11 patients who received vascular reconstruction operations, such as STA-MCA anastomosis, EDAS, RDP (reversed durapexia) and EMS, studies were performed before and after the operation. We cited the following findings as criteria for diagnosis: 1) A significant decrease in flow velocity of the cerebral arteries (MCA, ACA), although coexistence of decreased and increased velocities side by side were also noticed. 2) Decrease or absence of vascular reactivity to hypocapnia. 3) Transformation of the STA flow velocity wave form from an external carotid artery pattern to internal carotid pattern. 4) A significant increase in the flow velocity of the ophthalmic artery and transformation of the wave form. These changes were seen more remarkably in cases with abundant transdural anastomosis. If we obtained findings 1) and 2), Moyamoya disease was suspected. When additional findings 3) and/or 4) were obtained, the possibility of the disease was very high. The findings of TCD post-operatively, were also useful. If the STA was patent and functioning well, the flow velocity of STA increased dramatically and the flow pattern became similar to the internal carotid pattern. Observations of these pre- and postoperative characteristic changes in flow velocity and vascular reactivity in patients with Moyamoya disease see to be quite useful for the evaluation of the hemodynamics and should provide information for a follow-up study.
The significance of transcranial Doppler ultrasonography (TCD) in the detection of cerebral aneurysm was studied in twenty patients with subarachnoid hemorrhage. Transcranial Doppler arteriography (TCDA) and transcranial Doppler Tomography (TCDT) were used for evaluation in this study. In five of twenty patients (25%), turbulent flow in the aneurysm of the middle cerebral artery and internal carotid artery was detected. The diameter of the aneurysms was larger than 10 mm, except for one patient with a small aneurysm. The detection rate of cerebral aneurysm was the highest when TCDT was used. Cerebral aneurysms can be detected by conventional TCD, but the detection rate is not satisfactory compared with other neuroimaging modalities. Further development of TCD devices is needed for practical screening of an unruptured cerebral aneurysm.
The relationship between the angiographic distribution of vasospasm and the time course changes in MCA flow velocity was examined in 72 patients with aneurysmal subarachnoid hemorrhage. Postoperative carotid angiogram demonstrated no vasospasm in 13 patients, proximal vasospasm (vasospasm restricted to the M1 segment of MCA) in 16, peripheral vasospasm (vasospasm restricted to the M2 or M3 segment of MCA) in 11, and diffuse vasospasm in 32, respectively. Using a mean flow velocity of 120 cm/s as a cut-off value for angiographic vasospasm, the sensitivity of TCD was 80% and the specificity was 100%. The falsenegative cases were those with peripheral vasospasm (four patients) or diffuse vasospasm (two patients) . Twenty-nine patients developed delayed ischemic neurological deficits (DIND) (seven proximal, six peripheral, and 16 diffuse vasospasm) . Mean flow velocities increased higher than 150 cm/s in 18 patients with DIND, while they remained lower than 100 cm/s in six patients (four peripheral and two diffuse vasospasm) regardless of the development of DIND. These results suggested that peripheral vasospasm could not be detected by the measurement of blood flow velocity at the basal cerebral arteries alone.
To clarify the significance of transcranial Doppler (TCD) monitoring for detection of raised intracranial pressure (ICP), cerebral ischemia, and neuronal dysfunction in comatose patients with severe brain damage, vasoreactive correlations during hyperventilation (HV) and changes in cerebral perfusion pressure (CPP) were evaluated by continuous monitoring of TCD in the middle cerebral artery, jugular bulb oxygen saturation (SjO2), end-tidal CO2partial pressure, ICP and CPP, and quantitative EEG (qEEG) . TCD and gEEG (total and spectral power bands) were monitored in a total of 32 cases of severe head injury, CPP in 26, and SjO2in 16 for 7 days (mean) . Peak systolic, mean, and end-diastolic velocity (Vs, Vm, Vd), pulsatility index (PI), resistance index, and cerebrovascular resistance (CVR=CPP/Vm) were evaluated. a) CO2reactivity (ΔVm/ΔCO2, ΔSjO2/ΔCO2) and correlations with ICP and SjO2were compared within ischemic, normal, and hyperemic groups, based on minimal SjO2during HV. b) Effects of CPP changes were correlated with gEEG. a) HV: 1) No significant differences in TCD parameters and ΔVm/ΔCO2were observed among the three groups. However, ΔSjO2/ΔCO2was significantly high in the order of ischemic>normal> hyperemic groups. 2) Close correlations of ICP with Vm and CVR were identified. 3) Significant correlations of SjO2with CVR, Vm, Vs, and PI were observed frequently in the ischemic group. b) CPP: 1) In cases of close correlation between CPP (<60 mmHg) and Vm, there were significant correlations between all gEEG power bands and Vm. 2) Loss of gEEG was observed in four cases of Vm<36 cm/s, Vd=0, and PI>2.74. Continuous TCD monitoring is useful for the early detection of decreased cerebral circulation and increased CVR associated with intracranial hypertension, cerebral ischemia, and neuronal dysfunction, but not always for easy interpretation of the underlying pathophysiology in patients with severe brain damage.