TCDを用いて脳血管の血管運動反応を見ることが出来, 頸動脈狭窄や閉塞, その他の疾患で良く用いられている.この場合, 血管の直径が不変であれば, TCDでみる血流速度変化は脳血流量の変化を示すことになるが, このことは未だ明らかにはされていない.そこで著者らは, 頭蓋内血管の血流速度と頭蓋外血管 (頸部頸動脈) の血流量の変化を同時に測定し, この問題を明らかにしようとした.
頸動脈の血流量をM-mode color duplex systemを用い, 中大脳動脈の血流速度をTCDを用いて同時に測定した.32名のvolunteer (42±18才) を対象に5%炭酸ガスを吸入させつつ測定した.さらに, 内頸動脈は直接測定しにくく総頸動脈で測定するため, 外頸動脈領域における変化の影響を評価する必要がある.このため一側の内頸動脈が閉塞しているが眼動脈を介しての側副血行が明らかでない7名の患者 (67±12才) を対象としacetazolamideを投与しつつ測定した.炭酸ガスおよびacetazolamideにより, 頭蓋内血流速度は各々31%および39%まで増加し, 同時に総頸動脈の血流量は各々47%と50%にまで増加した.内頸動脈が閉塞している患者では頭蓋外血流量の変化は見られず, 外頸動脈領域では影響は受けないと考えられた.
これらの結果は, 中大脳動脈に於いては血流速度が亢進するだけではなく, 同時に炭酸ガスおよびacetazolamideにより各々6%と4%とにまで血管の直径が増大することを示唆している.この血管拡張が薬物の血管壁への直接作用によるものなのか, あるいは単純に圧に依存したものかは明らかではない.著者らは, さらにこの方法をくも膜下出血後の血管攣縮に伴う血行動態の解明にも有効な方法であろうと付け加えている.

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Purpose: High-intensity transient signals (HITS) are commonly detected during cardiopulmonary bypass (CPB) . However, the clinical significance of HITS during CPB is still controversial. Micro-bubbles are reported to produce HITS of more than 400-500 Hz. We attempted to elucidate the incidence of HITS exceeding 400 Hz during CPB. Methods: The subjects were 6 patients who underwent open heart surgery using CPB. HITS were detected by TC2020, PIONEER (Nicolet /EME) with a 2.0-MHz pulsed Doppler probe at the middle cerebral artery. Transesophageal echocardiography (TEE) was undertaken during the operation. Results: The total number of HITS during CPB was 1707±1392 (n=6) . Of the total HITS, 88.1±6.8% had a frequency of more than 400 Hz. On the other hand, HITS of less than 400 Hz were frequently detected at aortic cannulation, aortic decannulation and aortic cross-clamping. HITS of more than 400 Hz were detected in cases showing cardiac or aortic micro-bubbles in TEE. Conclusion: The present findings suggest that the majority of HITS during CPB reflect micro-bubbles, and that aortic manipulation may be related to the formation of solid micro-emboli. HITS frequency analysis may be useful for differentiating between micro-bubbles and solid micro-emboli formed during CPB.

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The purpose of this paper is to present our experiences using transcranial Doppler ultrasonography (TCD) in patients with pre and post ventriculoperitoneal (VP) shunt for hydrocephalus and burr hole operations in chronic subdural hematoma. By using Sonolayer α SSA-260A, Toshiba medical corporation, Japan, we performed TCD at pre operation and one week after operation in 14 patients since Feb. 1997 to Jan. 1998. There were four cases with idiopathic normal pressure hydrocephalus (NPH), NPH after subarachnoid hemorrhage (3), congenital hydrocephalus (3), NPH after traumatic brain injury (1), and chronic subdural hematoma (3) . We did TCD in all patients and evaluated the changes in mean flow velocity (MV), pulsatility index (PI), and their concurrent clinical corses. Result: The MV at pre operation was 40.1 ± 15.0 cm/s (mean±SEM), and 45.7±18.4cm/s at post operation. No significant change in MV was found between pre and post operation. (P=0.17) . The PI at preoperation was 1.09±0.05 and 1.09±0.07 at postoperation. No significant change in PI was found between pre and postoperation. (P = 0.99) . Many of cases got clinical improvement with increase in MV and decrease in PI, but some of cases have discrepancy between the TCD findings and their clinical improvement. These cases had parmanent focal brain injury in the computed tomography. TCD examinations in pre and post VP shunt or burr hole procedure are useful.

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太い脳血管で血流量が変化した時に血管径が変化するか否かが大きな問題となっている.TCDは非侵襲的に脳血流を測定しうるため, 広く用いられているが, 血流速度変化を血流量の変化の指標として用いることが出来るのは血管の直径が不変である場合である.しかしながらこの点に関しては未だ明確にはされていない.そこで著者らは, 種々の程度の血中炭酸ガス濃度下で, 中大脳動脈と, 血管径が変化しにくい静脈洞との血流速度を同時に測定し, 両者に於ける血管運動反応の差から血管径の変化の有無を検討した.
16名の若い健常者で, 種々の血中炭酸ガス濃度下で, 一側の中大脳動脈と対側の蝶形頭頂静脈洞 (sphenoparital sinus) と思われる静脈の両者を一対のTCDを用いて同時に測定した.高炭酸ガス血中濃度の状況下では, 中大脳動脈の平均血流速度は62.5±10.2cm/sから最高99±12.2cm/s (血管運動反応性は60.1±17.3%) に亢進した.一方, 蝶形頭頂静脈洞では17.8±5.7cm/sから34.5±14.3cm/s (血管運動反応性は91.4±25.9%) まで上昇し, より著明な亢進を示した.炭酸ガス濃度に対する血管反応性 (%/mmHg, EtCO₂) は中大脳動脈では4.5±1%/mmHg, 蝶形頭頂静脈洞では6.8±1.5%/mmHgであった.
以上より, この血管運動反応性の差は静脈に比べ中大脳動脈が拡張していることを示していると考えられる.すなわち, 拡張しにくい静脈洞の血流速度変化と中大脳動脈の血流速度変化との比較検討から, 中大脳動脈では最高血中炭酸ガス濃度下では9.5±7%の拡張が生じていることを示している.著者らは, 血流速度変化から血流量の変化を考える場合にこの点を十分注意する必要がある, と結んでいる.

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We examined the availability of B-mode ultrasonography (B-mode) for two patients who were followed up after stenting of the carotid artery, in comparison with angiography and 3D-CT angiography (3D-CTA) . The first patient was a 60-year-old man who had suffered an episode of cerebral ischemia, and the second was a 74-year-old man who had had several episodes of unconsciousness. On admission, about 75-80% focal stenosis of the carotid artery was demonstrated in both patients by angiography, 3D-CTA and B-mode ultrasonography. Stenting of the stenosed portion was done successfully in both cases. Postoperative examination (angiography, 3D-CTA and B-mode) revealed no occurrence of restenosis. B-mode appeared especially useful for revealing details in the stent. We observed a high-echoic layer inside the stent in the first case. We suggest that B-mode is an easy and non-invasive method that is useful for follow-up after stenting in the carotid artery.

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It is not widely known that therapeutic ultrasound has been developed for almost as long as diagnostic ultrasound. However, recent progress in ultrasound technology and medical imaging technology has brought therapeutic ultrasound into center stage, since it has excellent therapeutic features.
First, ultrasound can penetrate into the body more deeply than other forms of energy, for example microwaves and laser light. Second, its energy can be easily localized into a small region using an acoustic lens or a concave-shaped transducer. Therefore, ultrasound energy makes it possible to treat a small target inside the body without damage to surrounding normal tissue. Furthermore, mechanical, chemical and thermal effects can be chosen by selecting its frequency and intensity.
Ultrasound is a promising form of energy with many potential applications in the minimally invasive treatment (MIT) field.

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