抄録
Maximum blood flow velocity (BVmax), mean flow volume (BF), mean diameter (D), and diameter excursion (ΔD) of the common carotid artery were measured by an ultrasonic quantitative flow measurement system. Stiffness parameter β, representing one of the mechanical properties of the vessel, was calculated from measurement of blood pressure, D and ΔD. BVmax and BF were parameters of hemodynamics; D and β were parameters of vessel wall properties. BVmax and BF decreased with aging; D and β increased with aging. In patients with diabetes mellites, hypercholestemia and hypertension, the change in each parameter was found to be significantly greater than in normal subjects. In subjects with cerebral infarction, BF on the diseased side decreased significantly compared with that on the healthy side. BF on the healthy side was almost equal in normal subjects, but β valves on both sides in cerebral infarction cases were higher compared with the β valves in normal subjects. Reliability of BF and β which had been measured in living subjects (n=60) was supported by postmortum pathological findings. BF valves correlated inversely with the stenosis degrees of the carotid and cerebral arteries (r=-0.69, p<0.0001). In cases of BF≤6.4 ml/sec, all such cases had stenosis<50 %. β and common carotid arteriosclerosis had a correlation coefficient of 0.68 (p<0.01). β revealed the degree of common carotid arteriosclerosis present. The maximum limit of β in healthy subjects was 13, but β did not correlate with the stenosis degree of the carotid and cerebral arteries (r=0.18). From these results, we had to measure both BF and β, and the case with BF≤6.4ml/sec or β≥13 was diagnosed as arteriosclerosis.
We have succeeded in quantitatively measuring basal cerebral artery blood flow velocity using transcranial color Doppler tomography (TCDT). TCDT at 2.5MHz was able to recognize the middle cerebral artery (MCA) as a colored blood flow signal in sector images. In determining the angle between the ultrasonic beam and M1 portion of the MCA, a quantitative phasic velocity sonogram was recorded using real-time pulse Doppler. Maximum and mean blood flow velocities were calculated from the sonogram. The inverse correlation between BVmax and age was close, the correlation ratio being -0.64 (p<0.01). In the arteriosclerosis group, the BVmax was significnatly lower than in the same decade in the healh y group. The TCDT method was very useful in diagnosing cerebral arteriosclerosis noninvasively and directly.
