山田 利津子¹, 辻本 文雄², 菅田 安男³

Ritsuko YAMADA¹, Fumio TSUJIMOTO², Yasuo SUGATA³

¹聖マリアンナ医科大学眼科学教室, ²聖マリアンナ医科大学臨床検査医学教室, ³日産厚生会玉川病院眼科

¹Department of Ophthalmology, St. Marianna University School of Medicine, ²Department of Laboratory Medicine, St. Marianna University School of Medicine, ³Department of Ophthalmology, Nissan Tamagawa Hospital

キーワード : Doppler angle, pulsed Doppler method, fast Fourier transformed wave, ophthalmic artery

目的：頸動脈閉塞性疾患症例の眼動脈血流方向に関する多くの報告が超音波パルスドプラ法によってなされた．眼動脈測定の重要性が認識されたことから，眼科領域の検者だけでなく，新たに眼動脈の血流測定をする眼科以外の検者が増えてきた．眼動脈の血流測定では超音波ビームの投射方向を変化させることにより，1ヵ所のカラードプラ信号部から順方向・順逆両方向および逆方向の血流波形が採取されることについて検討した．対象と方法：同意を得た健康成人を対象に眼窩内眼動脈の血流波形を測定した．超音波診断装置SSA-700A（東芝）で中心周波数7.5MHzの探触子を用い，仰臥位で閉瞼させ，反対側は直上を注視させた．接触法でヒドロキシエチルセルロース点眼液を音響カプラとして用いた．眼動脈の信号を捕らえ，超音波ビームの投射角度を変えることにより血管の走行方向とビームの角度を変化させ，血流波形の形状変化を観察した．結果と考察：超音波ビームの投射方向をわずかに変える事により，同じ被験者から順方向波形・逆方向波形ならびに両方向血流波形が記録出来た．眼動脈の走行には多様性があるため，血流測定には眼位ならびに血管走行方向を確認し，順方向，超音波ビームの方向と血流方向のなす角度が出来るだけ小さくなるように測定し，3回以上の測定により再現性を確認することが必要であると思われた．結論：眼動脈の血流測定では超音波ビームの投射角により，1箇所のカラードプラ信号部位から順逆両方向の波形が得られることが示唆された．

Purpose: Direction of blood flow in the ophthalmic artery observed using the Doppler method in ocular diseases and in relation to occlusive carotid artery diseases has been discussed by many researchers in various departments. Underlying problems are discussed from the fact that any type of flow pattern, even reversal, may be obtained simply by changing the angle of the probe. Subjects and Methods: Pulsed Doppler waves were recorded in the orbital ophthalmic arteries of healthy individuals under prospectively obtained informed consent. An SSA-700A (Toshiba) ultrasound unit equipped with a 7.5 MHz linear probe was used. Color Doppler images were acquired in the supine position through a closed eyelid while gazing straight ahead with the collateral eye and contact methods employing hydroxyethyl cellulose ophthalmic solution as an acoustic coupler. Pulsed Doppler images were recorded while slightly changing the angle of the probe pointing at the targeted position. Results and Discussion: Forward, backward, and bidirectional waves were recorded from the same part of the orbital ophthalmic artery of the same person while varying the angle of the probe. Various pulsed Doppler wave forms were detected from the same examinee. The intraorbital course in the ophthalmic artery is known to retain rich anatomical variations. A detailed description of probe-positioning is an absolute requirement when considering direction of flow and the flow pattern of the ophthalmic artery. We think that examinations of velocimetry in the ophthalmic artery need to be conducted, so as to minimize the angle between the underlying direction of blood flow and the ultrasound beam, which is reproducible in measuring more than three times. Conclusion: This study suggests that forward, backward, and bidirectional pulsed Doppler waves may be obtained by simply changing the angle of the Doppler beam and the ophthalmic artery.