We measured simultaneously the flow velocity curves of the common carotid artery and the middle cerebral artery to evaluate the relationship between the systemic and cerebral circulations in the early neonatal period. Eligible for inclusion in this study were 20 healthy full-term neonates. Doppler ultrasound examinations were performed at 1, 2, 3, and 4 days after birth. The flow velocity curves of both arteries were recorded using a multi-channel Doppler system. Systolic maximal velocities and end-diastolic velocities were measured, and resistance indices (RIs) were calculated. The flow velocity of the middle cerebral artery increased during the first three days after birth, but that of the common carotid artery did not change. The RI of the middle cerebral artery remained constant, but that of the common carotid artery decreased on the third day after birth. These data suggest that the cerebral arteries might work as resistance vessels.

View full abstract

Transcranial Doppler sonography (TCD) is a useful method for investigating the hemodynamics of cerebral arteries. Phase-contrast (PC) MRA measures a vector quantity that contains information about blood flow direction and velocity. The purpose of this study was to evaluate the clinical usefulness of these modalities for investigating the hemodynamics of the ophthalmic artery (OA) and superior ophthalmic vein (Soy) . Between 1991 and 1996, ten patients with moyamoya disease and 6 patients with carotid-cavernous fistula (CCF) were evaluated using both methods. TCD was carried out through the orbital window. On the other hand, three-dimensional PC MRA and two-dimensional PC cine MRI were used with various velocity encoding gradient, and the flow direction in the OA and SOV was evaluated from the phase image. The results were as follows: (1) In moyamoya disease, the mean flow velocity (MFV) in the ophthalmic artery was relatively high, and reverse flow was seen in 3 of the 20 affected sides in both the TCD and PC MRA. (2) In CCF, the MFV in the SOV by TCD was elevated, although the level of the optimal velocity by PC MRA was relatively low. In conclusion, both TCD and PC MRA are clinically useful for evaluating the hemodynamics of the OA and SOV in moyamoya disease and CCF. Comprehensive evaluation using these two modalities should be done to understand the hemodynamics of these diseases.

View full abstract

Objective: Power Doppler imaging (PDI), rather than conventional color flow imaging (CFI), offers significantly better spatial resolution for visualization of intracranial vessels. When blood flow volume (Vf) is evaluated on the basis of PDI measurement of vessel diameter (Vd), there is a tendency to slightly overestimate Vd in normal controls and various brain lesions. The aim of this experimental study utilizing a Doppler flow phantom was to verify the reliability of Vf estimation based on PDI measurement of Vd. Methods: Four tubes of different sizes (2, 4, 6, 8 mm) in the phantom were perfused with artificial blood using a Doppler flow controller and pumping system (ATS) . The 2-MHz phased-array probe of an Ultramark 9 HDI (ATL) was fixed to two different planes [angle of incidence (AOI), 34°C and 72°C] of the phantom, and Vd values were measured (n=6) under the following conditions: 1) AOI and depth (adjusting the focal zone), 2) Utilizing 34° AOI: (1) Size of color overlay area (COA) associating with debated spatial peak temporal average-mechanical index (SPTAd-MI), (2) color gain (CG), wall filter (WF), and pulse repetition frequency (PRF), (3) Vf (CG 65 and 75%) . Results: 1) AOI and depth (focal zone) : there were no apparent difference in Vd at various depths adjusted to focal zones in the two AOI. 2) COA and SPTAd/MI: there was a relationship between Vd and COA size in association with changes in SPTAd/MI. When utilizing a COA of minimum size, the measured Vd was minimal. 3) Parameters: (1) CG: CG increases accompanied Vd increases up to 70%. There was no difference in Vd between 70% and 82%. It was not possible to measure Vd at 83% or more due to increasing background noise. When the optimal CG (70%-82%) was used, Vd was exaggerated by 2 mm. (2) WF: WF increases were accompanied by Vd decreases. (3) PRF: PRF increases were associated with Vd decreases. (4) Vf: Vf increased to 40 ml/min in the 2-mm tube, 53 ml/min in the 4-mm tube, 89 ml/min in the 6-mm tube, and 137 ml/min in the 8-mm tube. Vd increases were concomitant with Vf increases when 65% CG was used. At 75% CG over time-averaged peak velocity of 10 cm/s, Vf values (ml/min) were 14 for the 2-mm tube, 32 for the 4-mm tube, 64 for the 6-mm tube, and 105 for the 8-mm tube and the measured Vd was constant in spite of the Vf changes. Measured diameters were roughly exaggerated by 2 mm. Conclusions: When fixed values of CG, WF, PRF, and COA were used, vessel diameters measured by PDI were consistently exaggerated and almost unaffected by changes in Doppler AOI and depth, focal zone, and Vf (except under 10 cm/s) . This study thus validated the reliability of quantitative flow volume estimation on the basis of vessel diameter measurements by PDI.

View full abstract

We studied the relationship between carotid plaques and plasma endothelin-1 concentration (ET-1) in patients with essential hypertension.
A total of 212 patients (83 males, 129 females, 36-84 yr, mean age 63 yr) with essential hypertension (WHO stage I-II), and 109 age-matched control subjects (35-79 yr, mean 61 yr) were enrolled in this study. Plaque (defined as intima-media thickness 50% thicker than neibour intima-media thickness) in the both side of common carotid artery and the both side of internal carotid artery were measured by B-mode ultrasonography. Plaques were classified into soft plaque (without calcification) and hard plaque (with calcification) . ET-1 was measured by enzyme immunoassay.
ET-1 levels were significantly higher in hypertensive patients than in control subjects. The frequency of plaque in patients with high ET-1 levels (ET-1≥1.71 pg/ml) was signficantly higher than those with normal ET-1 levels (ET-1<1.71 pg/ml) . The frequency of soft plaque in patients with high ET-1 levels was signficantly higher than those with normal ET-1 levels. But there was no difference between the frequency of hard plaque in patients with high ET-1 levels and that with normal ET-1 levels.
These results indicate that high ET-1 levels with essential hypertension may play a role in the progression of carotid plaque without calcification.

View full abstract

A rare case of duplicated spinal dural arteriovenous fistulae is reported. A 31-year-old woman suffering from congestive myelopathy was admitted. Spinal angiography demonstrated dural arteriovenous fistulae at the T10/11 intervertebral foramen. Surgical interruption of the fistulae was performed using micro-Doppler monitoring. Intraoperative micro-Doppler monitoring was performed on the dorsal redundant perimedullary vein, which showed an arterial spectrum. After ligation of the retrogradely irrigating radiculomedullary vein along the right T10 dorsal root, the arterial spectrum diminished, but was restored with time. Repeated temporary clipping under micro-Doppler monitoring disclosed a second dural arteriovenous fistula fed by the anterior spinal canal artery. The arterialized vein proximal to the coronal plexus was coagulated. After this procedure, the arterial spectrum disappeared on the dorsal perimedullary vein. Postoperatively, the patient's neurological deficits improved gradually.
In this case, a second arteriovenous fistula located ventrally was found in addition to the usual radiculomeningeal arteriovenous fistula around the dorsal root. Intraoperative micro-Doppler monitoring was effective for detecting the residual arteriovenous shunting through the second arteriodural venous fistula.
Microdoppler monitoring is an easily available and noninvasive monitoring technique. Use of this monitoring method will yield excellent results in surgery for spinal dural arteriovenous fistulae, and it is especially useful in rare cases such as duplicated arteriovenous fistulae.

View full abstract

The goal of acoustic neuroma surgery is to accomplish total removal of the tumor with functional preservation of the facial and cochlear nerves. A conventional ultrasonic aspirator is too large and heavy for performance of fine and delicate surgical maneuvers. We developed a compact and light-weight handpiece suitable for acoustic neuroma surgery. The handgrip is designed to fit the surgeon's hand, and is well balanced. Suction pressure can be controlled with a finger by closing or opening a hole set in the handpiece. The horn portion is exchangeable for one with a different tip diameter; the smallest diameter is 1.5 mm. This ultrasonic aspirator has been used in 48 acoustic neuroma operations. The aspirator enabled removal of a relatively hard tumor including one in the internal auditory canal quickly, without damage to the surrounding tissue. The maneuverability of the aspirator is similar to the conventional suction tube, in view of the suction-pressure control system and handgrip. Holding a regular suction tube in one hand and the ultrasonic aspirator in the other is the most convenient method for removing a tumor safely because the surgeon can always confirm the amount and nature of the residual tumor by touching the tumor with the regular suction tip.

View full abstract

Three-dimensional echo (3D-Echo) technology has been under development in the world for 10 years, and great progress has been made in both echographic equipment and personal computers. The principles of 3D-Echo have not changed, but now three-dimensional calculation has become practical. Current 3D-Echo systems have the following merits, and also demerits which must be improved.
Merits
1. Wide area of view
2. Solid form
3. Feasibility of volume and weight measurements
Demerits
1. No real-time display
2. No 2D image information
3D-Echo diagnostic ability and technology will be available in the near future. We need to develop performance, including highspecd (realtime), ease of operation, and various forms of measurement such as dynamic imaging, and also reduce the cost.

View full abstract