A comparison of three-dimensional time-of-flight magnetic resonance angiography (MRA) with B-mode and colorcoded Doppler ultrasonography (US) was made in 56 carotid arteries in 28 individuals (male 24 and female 4, age 64.5±7.2 years) . The degree of stenosis of the carotid arteries was classified as normal: 0-19%, mild: 20-39%, moderate: 40-59%, severe: 60-79%, critical: 80-99%, and occlusion: 100%. MRA showed two false-positive cases, one false-negative case and one undergraded case. US showed no false-positive and no false-negative case. MRA was relatively insensitive for detection of mild stenosis, but showed good correlation with US in detection of severe, critical stenosis or occlusion. Comparison of US with conventional angiography demonstrated 100% accuracy for carotid stenosis (sensitivity 100%, specificity 100% for stenosis) . Comparison of MRA with US demonstrated 95% accuracy for carotid stenosis (sensitivity 98%, specificity 96% for stenosis) . It was concluded, that the diagnostic pitfalls of MRA are artifacts caused by turbulent nonlaminar flow, flow separation, reversal of flow and motion. US is useful for interpreting intraplaque morphology and for detecting turbulence or vortex flow using color Doppler flow imaging. However, the major limitation of US is the difficulty in detecting plaques in the high cervical carotid area. This study suggests that combined use of MRA and US is accurate for detection and evaluation of carotid stenosis in patients with cerebrovascular symptoms.

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To visualize the vascular anatomy of the brain, we have developed a system for producing three-dimensional (3D) color Doppler images from a series of two-dimensional color Doppler images. Two-dimensional images of cerebral vessels were digitized, and specially designed software reconstructed the 3D volumes and displayed volume-rendered images of the cerebral vessels during surgery for cases of aneurysm or arteriovenous malformation. Intraoperative 3D color Doppler images represented as cerebral vessels were successfully obtained from both of two patients. Especially in the patient with an aneurysm, 3D color flow images were equal in their displayed features to images obtained by CT angiography. We discuss the possibility of the applying ultrasound 3D imaging in patients with neurosurgical disorders.

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大動脈弓部の動脈硬化性病変 (プラーク) は, 脳梗塞の塞栓源のひとつと考えられている.経食道心臓超音波検査法 (TEE) は大動脈プラークを確認するため脳卒中患者に日常的な検査として行われている.ところが, TEEは比較的侵襲的な検査であり, 全ての患者が耐えうるわけではなく, また, 遠位上行大動脈や大動脈弓部では気管支が障害となってよく観察されないこともある.
Bモード超音波検査法は, 頸動脈のアテローム性動脈硬化病変の評価法として既に確立され, 脳梗塞の塞栓源として病変の組織性状との関連も研究されているが, 最近の研究では大動脈弓部のプラークの観察にも使われてきている.筆者らは, 20人の患者で経皮的Bモード超音波検査法によって鎖骨上窩外側部よりの大動脈弓部の画像化を試み, その結果をTEEと比較した.大動脈を近位上行大動脈, 遠位上行大動脈, 近位大動脈弓, 遠位大動脈弓の4ヵ所に分け, プラークを確認した.プラークは性状により単純病変 (<4mm) か複合病変 (>4mm) かに分けた.
結果は, 近位上行大動脈において単純プラーク8個がTEEで同定されたが, Bモード法では確認されなかった.遠位上行大動脈においては複合プラーク1個が両検査法で確認されたが, さらにBモード法で複合プラークと単純プラークが1個づつ認められた.近位大動脈弓では, 単純プラーク6個と複合プラーク5個が両検査法で確認されたが, さらにTEEで複合プラークが1個認められた.遠位大動脈弓では, TEEで単純プラークが2個と複合プラークが2個認められ, Bモード法で複合プラークが3個認められた.
Bモード法は, TEEと比べても遠位上行大動脈から大動脈弓にかけてのプラークの観察に遜色ないが, 近位上行大動脈における単純プラークは確認が困難であった.しかし, 遠位大動脈弓では, TEEで観察されないプラークがBモード法で描出される場合も見られた.Bモード超音波検査法は, 大動脈弓部のプラークを総合的に評価する際にTEEの補足的な役割を果たし, 描出されたプラーク病変を連続的に観察する際には特に有用な非侵襲的な検査法であるといえる.
組織プラスミノーゲン活性化因子の超急性期静脈内投与は脳卒中の予後を改善し得るが, 広範な神経脱落症状を伴う中大脳動脈 (MCA) 主幹部閉塞による大梗塞にその効果はあまり期待できない.適応症例の迅速な選択が必要だが, CTによる病巣評価は超急性期には困難である.一方, 頭蓋内主要血管が開存しているか否かは病状の初期予後を左右するが, 血管撮影には時間がかかり侵襲的でもある.急性期患者にMRアンギオグラフイーを施行するのはしばしば困難であり, 経頭蓋超音波ドプラ法 (TCD) は血管閉塞の診断能に問題がある.経頭蓋カラーデュプレックス超音波法 (TCCD) はこういった状況を変える可能性があるが, 血流信号の増強なしでは信号検出能が低く, 診断に応用できない場合も多いものと思われる.筆者らは虚血性脳卒中急性期における造影TCCDの診断上の有用性を検討し, また, 本法により評価し得た血管病変が予後を予想する上で臨床的に重要かを検討した.この論文では, 神経症状発症から5時間以内に臨床評価, CT, 超音波法が施行された連続23例の頸動脈領域脳卒中患者が提示され, TCD, 非造影TCCD, 造影TCCD (Levovist, 4g, 300mg/mL) について, MCA閉塞と血流速低下を検出する能力が比較された.ここで, MCAの血流速低下はその潅流領域における血行動態障害を示唆するものである.神経脱落症状はNIH Stroke Scale scoreを用いて定量化され, 入院4日目にscoreが4点以上低下した場合, または, 脱落症状が完全に消失した場合をもって症状の初期改善と定義された.造影TCCDを用いた場合, 20例の患側大脳半球にて頭蓋内血管病変の診断が可能であったが, 非造影TCCDまたはTCDを用いた場合ではそれぞれ7例と14例にて明確な診断がなされた (P=0.0001) .造影TCCDは内頸動脈遠位閉塞 (carotid-T occlusion) の評価に優れており, また, 閉塞主要動脈を血流速が低下した開存動脈から鑑別する点でも優れていた.造影TCCDに要する平均検査時間は, 検討する血管数 (MCA分枝を含むか否か) により5～7分であった.ロジステイック回帰分析の結果, MCAが血流速の低下なく開存していることは, 症状の初期改善を予想する唯一の独立因子であった (P<0.01) .以上の結果より, 造影TCCDは頸動脈領域脳卒中の初期予後を評価する上で将来性のある検査法であり, それは非造影TCCDやTCDよりも優れていると筆者らは考えている.

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A study was conducted to evaluate the relationship between ophthalmic artery (OA) color Doppler flow imaging (CDFI) and single photon emission computed tomography (SPECT) in ischemic cerebrovascular diseases.
We examined 32 patients (mean age; 64 years) having ischemic cerebrovascular diseases, who underwent OA CDFI and SPECT within ten days.
The OA CDFI findings showed a normal pattern in 3 patients, a sclerotic pattern in 9, a stenotic pattern in 11, and a reversed pattern in 9. SPECT showed severe hypoperfusion in 8 patients, moderate hypoperfusion in 8, mild hypoperfusion in 6, and normal perfusion in 10. Most of the cases with a normal and sclerotic pattern by OA CDFI showed normal or mild hypoperfusion on SPECT. Among the eleven patients showing the stenotic pattern, six (55%) showed normal or mild hypoperfusion on SPECT. The SPECT findings in the nine patients with the reversed pattern were severe or moderate hypoperfusion.
Among the ischemic cerebrovascular diseases, the cases showing a normal, sclerotic, and reversed pattern by OA CDFI correlated well with the SPECT findings. OA CDFI should be performed with SPECT for a more precise understanding of intracranial hemodynamics.

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Carotid duplex ultrasound and transcranial Doppler (TCD) monitoring during carotid endarterectomy (CEA) is described. The safety of this procedure is crucial in determining the value of CEA. Eight CEAs have been performed at our center since the introduction of power Doppler imaging (PDI) in duplex ultrasound. PDI visualizes intravascular morphology from the integrated power of the reflected echo, mainly from red blood cells, which delineates the hypoechoic plaque. We examined the extent of stenotic lesions and plaque morphology in this series of 8 cases. PDI is useful for depicting the stenotic vessel lumen and the extent of the lesion, especially in hypoechoic atheromatous plaque, whereas conventional color Doppler flow imaging is superior for demonstrating the flow pattern in the carotid artery. Although PDI enhances surface morphology and depicts rough structures, its image quality is not adequate for delineating the ulcerative plaque surface clearly. In two cases, the distal ends of the stenotic lesion were not demonstrated due to difficulty in applying the echo probe. TCD provides hemodynamic information on the cerebral hemisphere during and after CEA, and allows prompt correction of impaired cerebral perfusion. With the aid of noninvasive monitoring using duplex scanning and TCD, CEA can be performed with real-time information on vessel shape and blood velocity, thereby reducing perioperative cerebrovascular complications.

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Cardiogenic embolism is one of the main causes of stroke. We analyzed the prevalence of microembolic signals (MES) in patients with recent cardiogenic embolism using a multigate technique. We examined 9 patients with cardiogenic embolism and 10 healthy controls, performing transcranial Doppler (TCD) monitoring from one middle cerebral artery using a 2-MHz probe of a multigated tanscranial pulsed Doppler system. The prevalence of MES was 22%. Most of the patients receiving antithrombotic therapy showed no MES. Two patients with acute stroke before initiation of therapy had no MES. In one of them, TCD detected no MES at 4 days after the onset of stroke, but another embolic stroke recurred only one day after TCD monitoring. All the healthy controls were free of MES. TCD was useful for confirming the stroke mechanism and for predicting individual prognosis in some patients. The prevalence of MES was not so high, and TCD did not always detect MES in patients with acute cardiogenic embolism. Recording for longer than 30 min, or on multiple occasions per patient will be necessary.

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The history of ultrasound diagnostic equipment began with the A-mode machine. Nowadays, not only pulsed Doppler, but also color flow mapping can be done on a real time B-mode machine. The circuit of the ultrasound transmitter/receiver, the so-called beam former, will soon be digitized, and this will markedly improve its performance.
The diagnostic ability of ultrasound equipment will be expanded to a wide range of applications, such as 3D display, clinical visualization of ultrasound contrast media, etc..

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