菅田 安男¹, 根本 喜久郎²

Yasuo SUGATA¹, Kikurou NEMOTO²

¹日産厚生会玉川クリニック眼科, ²リオン株式会社聴能技術部

¹Nissan Koseikai Tamagawa Clinic Eye Clinic, ²Rion Company Ltd Division of Audiological Technology

キーワード : high-frequency ultrasound, spontaneous echo contrast, erythrocyte aggregation, dietary effect

広帯域の30 MHzアニュラアレイ振動子を装着した超音波診断装置により手根部で2-3 mm径の皮静脈を観察した. 圧迫を加えることなく正常人の血管内に血流からの反射を認めた. このエコーは食後約1時間で増強し, 静脈の駆血によってさらに増強した. 静脈の圧迫による鬱血で観察されている血液エコーや, 心疾患, 深部静脈血栓症などに観察されるもやもやエコーに類似のエコーと考えられる. もやもやエコーは赤血球凝集現象の生体指標として10 MHz前後の周波数により血液鬱滞や血栓形成の危険因子の検索に用いられている. 本研究で自然状態にも表在静脈中に赤血球の集合体が存在し, 摂食による生理的な血球の環境変化にも変動することが示唆された. 30 MHzにより検出された血液エコーは赤血球あるいは低凝集度の赤血球の反射をも含むと考えられ, 生体で赤血球凝集現象を検討する手段になると考えられる.

A superficial vein in the wrist of a normal subject was examined with a high-frequency (30 MHz) ultrasound system with an annular-array broadband transducer. Spontaneous echo contrast was observed without compression in a cephalic vein 2 to 3 mm in diameter in the wrist. This echo was enhanced 1 hour after the subject had eaten and was further enhanced when the central side of the vein was compressed. Spontaneous echo contrast seen in larger veins studied using transmission frequencies of about 10 MHz has often been considered analogous to erythrocyte aggregation (rouleau formation) seen in cardiovascular moya-moya echo or other thromboembolic conditions. This increased spontaneous echo contrast seen after the subject has eaten a meal appears to resemble the aggregation of erythrocytes produced by compressing larger veins. The 30-MHz transducer detected echoes from blood in veins much smaller than those in which it had been detected previously. These echoes may have resulted from factors including erythrocytes or smaller rouleaux, as well as larger rouleaux. This intravenous echo contrast in superficial veins may prove useful in the noninvasive study of the physiologic dynamics of erythrocyte aggregation.