Detection of clinically silent intracranial emboli ipsilateral to internal carotid occlusions during cerebral angiography

OBJECTIVE: Embolic ischemic events have long been suspected to occur in the cerebral arteries distal to an ipsilateral occluded internal carotid artery (ICA). Documentation of microemboli by transcranial Doppler sonography during catheter angiography in patients with ICA occlusions provides objective evidence of such distal emboli. SUBJECTS AND METHODS: Seven patients undergoing carotid angiography were evaluated with transcranial Doppler sonography. Patients were also screened for ICA occlusions using carotid duplex sonography. In the seven patients, we saw five right ICA occlusions and two left ICA occlusions. Real-time visual and auditory confirmations of emboli were obtained by recognizing their specific spectral signatures and harmonic qualities. Routes of collateral flow were determined from angiography. Specific phases of the examination were correlated with embolic occurrences. RESULTS: Overall, emboli were seen during all phases of arteriography. In the individual patients, emboli were identified in one to four of the eight angiographic phases we defined. Most emboli occurred during catheter flushing and contrast injection rather than during wire and catheter manipulation. The emboli were detected in the middle cerebral artery distribution ipsilateral to the occluded ICA in all seven patients. Collateral flow patterns included, in four patients, external carotid artery-to-ICA collateral flow; in all seven patients, patent anterior communicating arteries; and in three patients, patent posterior communicating arteries. CONCLUSION: Emboli seen in middle cerebral arteries ipsilateral to occluded ICAs during cerebral angiography strongly indicate that emboli can occur distal to an occlusion. Our findings support the thought that emboli arising from sources proximal to an occluded ICA may reach the hemisphere distal to the occlusion, resulting in parenchymal ischemia or infarction.     

颅内交通动脉瘤与Willis环血流动力学变化的关系

目的；探讨颅内交通动脉瘤与Willis环血流动力学变化的关系。资料与方法，回顾性分析199例数字减影脑血管造影资料。结果前交通动脉瘤，A1优势征多见；后交通动脉瘤，非基底动脉共血与基底动脉供血比较无差异。结论：颅内前交通动脉瘤的形成与Willis前环的血流动力学变化有关，后交通动脉瘤与Willis后环的血流动力学变化尚未见明显关系。     

Circle of Willis in newborns: color Doppler imaging of 53 healthy full- term infants

To establish the usual pattern of flow in the circle of Willis in newborns, the authors scanned 53 healthy full-term infants within 3 days of birth with color Doppler imaging. All examinations were performed and images interpreted by the same experienced individuals. The basilar, internal carotid (ICA), and anterior and middle cerebral arteries were seen in all infants. Vertebral, posterior cerebral, superior cerebellar, and posterior communicating (PCoA) arteries were seen in most infants. PCoA flow was from the ICA toward the posterior cerebral artery in 73 (98.6%) of the 74 vessels that were seen. Flow in the anterior communicating artery was seen in six infants, indicating dependence of an anterior cerebral artery on contralateral ICA perfusion. Two pitfalls involving the distal portion of the ICA were noted: This vessel could be confused with the proximal portion of the anterior cerebral artery or cavernous sinus if real-time images were not interpreted carefully. Variant patterns of flow included tortuous basilar arteries (n = 2), reversed PCoA flow (n = 1), and inferior angulation of the proximal portions of the anterior cerebral arteries (n = 2). Color Doppler imaging allows a detailed analysis of the circle of Willis in newborns and detection of some anatomic variations.     

Transcranial color-coded duplex sonography in unilateral flow-restrictive extracranial carotid artery disease.

PURPOSETo provide transcranial color-coded duplex flow-velocity data for the basal cerebral arteries in patients with unilateral flow-restrictive extracranial carotid artery disease, and to compare these data with the flow velocities obtained in healthy control subjects.METHODSTranscranial color-coded duplex sonography was performed in 78 patients with different patterns of cross flow through the anterior and posterior communicating arteries associated with unilateral obstruction (70% to 100%; 46 stenoses and 32 occlusions) of the internal carotid arteries. Peak systolic, mean, and end diastolic velocities were measured in the anterior, middle, and precommunicating and postcommunicating posterior cerebral arteries. These measurements were compared with the values obtained in 125 age- and sex-matched health control subjects.RESULTSPatients with anterior communicating artery cross flow to the middle cerebral artery (63%) had increased peak velocity in the anterior cerebral artery and decrease peak velocity in the middle cerebral artery on the obstructed (ipsilateral) side, and increased peak velocity in the anterior cerebral artery on unobstructed (contralateral) side. Patients with anterior communicating artery cross flow to the pericallosal artery (19%) had increased contralateral peak systolic velocity and mean anterior cerebral artery velocities. Patients without anterior communicating artery cross flow (18%) had normal peak velocities in the anterior and middle cerebral arteries. Patients with posterior communicating artery cross flow (42%) had ipsilaterally decreased peak systolic and mean middle cerebral artery velocities and increased peak velocities in the precommunicating posterior cerebral artery. Patients without posterior communicating artery cross flow (58%) had ipsilaterally decreased peak systolic and mean middle cerebral artery velocities.CONCLUSIONOur findings suggest that typical abnormalities of basal cerebral artery flow velocities occur in patients with unilateral 70% to 100% obstruction of the internal carotid arteries resulting in different patterns of cross flow through the circle of Willis.     

Transcranial color-coded duplex sonography in the evaluation of collateral flow through the circle of Willis.

PURPOSETo determine the sensitivity, specificity, and positive and negative predictive values of transcranial color-coded duplex sonographic (TCCD) evaluation of cross flow through the anterior (ACoA) and posterior (PCoA) communicating arteries in patients with occlusive cerebrovascular disease.METHODSWe studied prospectively 132 patients (37 women, 95 men; mean age, 60 years) with stenoses of more than 69% reduction in vessel diameter (n = 93) and occlusions (n = 52) of the internal carotid artery, and three occlusions of the basilar artery. The sonographer was aware of extracranial sonographic findings but was blinded to the results of cerebral angiography.RESULTSNine patients (7%) with thick bones preventing transtemporal insonation and three patients (3%) with occlusions of the middle (n = 3) and anterior (n = 1) cerebral arteries were excluded. Sensitivity of TCCD for detection of collateral flow through the ACoA in patients with occlusive carotid artery disease was 98%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 98%. The corresponding values for the PCoA were 84%, 94%, 94%, and 84%, respectively. All three functional PCoAs were identified in patients with occluded basilar arteries.CONCLUSIONTCCD is a valuable method for noninvasive evaluation of cross flow through the ACoA in patients with adequate sonographic windows. However, TCCD evaluation of cross flow through the PCoA is less reliable, because hemodynamic criteria may cause falsely positive and falsely negative results.     

Correlation of cine MR velocity measurements in the internal carotid artery with collateral flow in the circle of willis: Preliminary study

The velocity-phase relationship intrinsic to phase-contrast magnetic resonance (MR) angiography permits the quantitative and qualitative assessment of blood flow. The ability to measure velocity and vessel cross-sectional area allows noninvasive assessment of volume flow rate (VFR) in the internal carotid artery (ICA). Phase-contrast techniques also demonstrate flow direction. Using two-dimensional cine phase-contrast angiography, the authors evaluated VFR in the ICA and collateral flow about the circle of Willis in 15 patients with ischemic neurologic symptoms. The VFR in each carotid artery was correlated with the degree of stenosis and presence or absence of abnormal circle of Willis collateral flow. There was a correlation between a decrease in VFR and abnormal circle of Willis collateral flow. In addition, a correlation between severe stenosis and a decrease in VFR was found. In patients with ischemic neurologic symptoms without severe stenosis (<70% diameter stenosis), no decrease in VFR was seen. It is hoped that flow quantification and directional flow imaging with phase-contrast angiography will help further characterize carotid artery occlusive disease by enabling assessment of VFR changes associated with ischemic neurologic symptoms. This study also supports the hypothesis that two mechanisms-hemodynamic and embolic-play a role in ischemic neurologic symptoms.     

Basilar bifurcation aneurysm associated with bilateral internal carotid occlusion

Summary A case of subarachnoid hemorrhage from ruptured aneurysm of the basilar bifurcation associated with occlusions of both internal carotid arteries at the neck is presented. Each internal carotid artery mainly received collateral flow at the cavernous portion from the internal maxillary artery through anastomotic artery of the foramen rotundum. Posterior circulation also supplied collateral blood flow via the right posterior communicating artery. This case report suggests that hemodynamic stress may be regarded as an important factor in the formation or development of cerebral aneurysm.     

Intra-arterial thrombolysis of occluded middle cerebral artery by use of collateral pathways in patients with tandem cervical carotid artery/middle cerebral artery occlusion

BACKGROUND AND PURPOSE: Cervical internal carotid artery (ICA) occlusion with middle cerebral artery (MCA) embolic occlusion is associated with a low rate of recanalization and poor outcome after intravenous thrombolysis. Prompt revascularization is required to prevent disabling stroke. We report our experience on acute ischemic stroke patients with tandem ICA or MCA occlusions treated with microcathether navigation and intra-arterial thrombolysis by use of collateral pathways including the posterior or anterior communicating arteries, or both pathways.MATERIALS AND METHODS: We retrospectively identified 8 patients with proximal ICA occlusion associated with MCA embolic occlusions treated with intra-arterial thrombolysis (IA rtPA). Access to the occluded MCA was obtained via catheter navigation through intact collateral pathways, including posterior communicating (PcomA) or anterior communicating (AcomA) arteries, without passing a microcathether through the acutely occluded ICA. We assessed clinical outcomes using modified Rankin scale (mRS) and National Institutes of Health Stroke Scale (NIHSS).RESULTS: Eight patients with a mean age of 57 ± 4 years and median NIHSS of 14 were identified. Mean time from stroke onset to intra-arterial thrombolysis was 292 ± 44 minutes. The MCA was revascularized completely in 5 of the 8 patients via collateral intra-arterial rtPA administration. All of the patients had a favorable outcome defined as a mRS of ≤2 or more at 1 and 3 months'' follow-up after thrombolytic therapy. One patient had an asymptomatic petechial hemorrhage.CONCLUSION: In this small number of patients with tandem occlusions of the ICA and MCA, intra-arterial thrombolysis and recanalization of the MCA by use of collateral pathways to bypass the occluded ICA is a safe and efficacious therapeutic option.

Acute occlusion of middle cerebral artery (MCA) occurs in up to 50% of patients with occlusion of the internal carotid artery (ICA).¹ The prognosis of these patients is poor, with high rates of morbidity and mortality.² Intra-arterial thrombolysis can result in better outcomes in patients with acute occlusions of the MCA.³ There is currently no clear consensus on the optimal treatment approach for patients with acute ischemic stroke secondary to tandem ICA and MCA occlusions. Several different strategies have been used, including combined intravenous and intra-arterial thrombolysis by microcatheter navigation through the occluded ICA,⁴ mechanical thrombectomy,^5,6 or angioplasty with or without stent placement of the occluded ICA.^7-10 These approaches can be time consuming, and the increased complexity of the treatment is associated with increased potential risk for complications. We report our experience on the treatment of patients with acute ischemic stroke with tandem MCA and ICA occlusions treated with microcatheter navigation and intra-arterial thrombolysis with use of collateral pathways, including the posterior (PcomA) or anterior communicating (AcomA) arteries. To the best of our knowledge, there have only been 2 previous case reports described in the literature of use of this approach.^11,12     

Balloon test occlusion of internal carotid artery: Angiographic findings predictive of results

AIM: To reveal angiographic findings to predict the result of balloon test occlusion (BTO).METHODS: The cerebral angiograms of 42 consecutive patients who underwent cerebral angiography including both the Matas and Allcock maneuvers and BTO were retrospectively analyzed. Visualization of the anterior cerebral artery (ACA) and the middle cerebral artery (MCA) by the cross flow on the tested side during the Matas or Allcock maneuver was graded on a 5-point scale. Circle of Willis (COW) anatomy with respect to the presence/absence of a collateral path to reach the tested internal carotid artery (ICA) was classified into four categories. A univariate logistic analysis was used to analyze the associations between each angiographic finding and the BTO result. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for each finding were calculated.RESULTS: Five patients (12%) were BTO-positive and the remaining 37 patients (88%) were BTO-negative. Visualizations of the ACA and MCA as well as the COW anatomy were significantly associated with the BTO result (P = 0.0051 for ACA, P = 0.0002 for MCA, and P < 0.0001 for COW anatomy). In particular, good MCA visualization and the presence of an anterior connection (collateral path to the tested ICA from the contralateral ICA via the anterior communicating artery) in the COW were highly predictive for negative BTO (negative predictive value = 100% for both).CONCLUSION: A BTO result may be predicted by angiographic findings including ACA/MCA visualization and COW anatomy.     

Predicting hemodynamic ischemia by transcranial Doppler monitoring during therapeutic balloon occlusion of the internal carotid artery.

PURPOSEOur objective was to evaluate the sensitivity of transcranial Doppler (TCD) sonographic monitoring during permanent balloon occlusion of the internal carotid artery (ICA) in predicting hemodynamic ischemia.METHODSThirty-two consecutive patients underwent controlled therapeutic balloon occlusion of the ICA. Selection criteria included assessment of the circle of Willis by compression angiography, clinical tolerance during a 20-minute test occlusion, and TCD monitoring of the ipsilateral middle cerebral artery. The mean blood flow velocity (MBFV) (n = 32) and pulsatility index (PI) (n = 28) were recorded. In 25 patients, MBFV changes upon motor stimulation were recorded before and after ICA occlusion.RESULTSTwenty-eight (88%) of the patients had no complications. Three patients suffered delayed symptoms 30 minutes to 20 hours after balloon detachment. Two of these patients recovered spontaneously within 1 day, the other improved after extracranial/intracranial (EC/IC) bypass surgery. One patient, who did not tolerate the test occlusion, suffered a hemodynamic stroke despite EC/IC bypass before permanent balloon occlusion. No embolic complications occurred. The mean MBFV reduction was 20% (range, 0% to 55%); the mean PI reduction was 20% (range, 0% to 56%). No complications occurred in patients who had mild MBFV and PI reduction (30% or less, n = 21). All three patients with severe MBFV or PI reduction (> 50%) had neurologic symptoms. Among those with moderate MBFV or PI reduction (30% to 50%, n = 8), symptoms developed in only one patient who had moderate reduction of both MBFV (33%) and PI (38%). Motor vasoreactivity showed wide variation and was markedly reduced in two symptomatic patients.CONCLUSIONTCD monitoring reflects changes in cerebral hemodynamics after therapeutic balloon occlusion of the ICA. MBFV and PI reductions under 30% are highly predictive of clinical tolerance. A reduction of more than 50% may be a critical threshold for the occurrence of symptoms; in such cases, EC/IC bypass should be considered before proceeding with permanent balloon occlusion.     

Relationship between circle of Willis morphology on 3D time-of-flight MR angiograms and transient ischemia during vascular clamping of the internal carotid artery during carotid endarterectomy

BACKGROUND AND PURPOSE: A potential source of complication at carotid endarterectomy (CEA) is cerebral ischemia caused by hypoperfusion during clamping of the carotid artery. Configuration of primary collateral pathways may be a major risk factor for development of transient cerebral ischemia during clamping. We investigated whether circle of Willis morphology on 3D time-of-flight (TOF) MR angiograms can reliably predict transient ischemia during vascular clamping of the internal carotid artery (ICA) in patients undergoing CEA. METHODS: Three-dimensional TOF MR angiography and CEA were performed in 117 patients. Patients had unilateral stenosis (n = 86), unilateral stenosis with contralateral occlusion (n = 21), or bilateral severe stenosis (n = 10) of the ICA. Circle of Willis morphology on preoperative 3D TOF MR angiograms was analyzed and correlated with intraoperative history of ischemia during vascular clamping of the ICA. RESULTS: Patients with unilateral stenosis or bilateral severe stenosis experienced transient ischemia during clamping of ICA at a low rate (11 [11%] of 96). In these groups, we found no specific circle of Willis patterns associated with development of intraoperative ischemia. However, patients with contralateral ICA occlusion experienced ischemia frequently during clamping of the ICA (12 [57%] of 21). In this group, incompleteness of the circle of Willis was significantly related to the risk of intraoperative ischemia (P =.005). CONCLUSION: In patients without contralateral ICA occlusion, circle of Willis morphology on 3D TOF MR angiograms cannot predict the development of intraoperative ischemia. However, in patients with contralateral ICA occlusion, incompleteness of the posterior part of the circle of Willis is a significant risk factor for development of ischemia during vascular clamping of the ICA.     

Reappraisal of flow velocity ratio in common carotid artery to predict hemodynamic change in carotid stenosis

BACKGROUND AND PURPOSE: Various Doppler criteria have been used to predict hemodynamically significant carotid stenosis. This study was performed to elucidate whether hemodynamically significant stenosis can be predicted indirectly by the blood flow velocity in the common carotid artery (CCA) measured with duplex ultrasonography in patients with unilateral stenosis of internal carotid artery (ICA). METHODS: Eighty-five patients who were scheduled to undergo carotid endarterectomy for unilateral stenosis of ICA origin were analyzed. The flow velocities and their side-to-side ratios in the CCA were calculated. The flow velocities in the CCA were measured with conventional ultrasonography and poststenotic blood flow with transoral carotid ultrasonography. Cerebral angiography was performed to evaluate the intracranial collateral flow. RESULTS: Among the absolute values and side-to-side ratios of Doppler flow velocities in the CCA, the end diastolic flow velocity (EDV) ratio in the CCA best correlated with the residual lumen area (r = 0.35; P = .0009), stenosis of diameter (r = 0.48; P < .0001), and poststenotic flow (r = 0.60; P < .0001). EDV ratios in the CCA were significantly lower in patients with collateral pathways (anterior communicating artery, P = .0005; posterior communicating artery, P = .004; ophthalmic artery, P < .0001; leptomeningeal collateral, P = .004). The optimal threshold value of the EDV ratio in the CCA for the presence of intracranial collateral flow and stenosis of diameter > or = 70% was 1.2. Those for tight stenosis in a cross-sectional area >95%, the reduction of poststenotic flow, and poststenotic narrowing were 1.4, 1.5, and 1.6, respectively. CONCLUSION: The EDV ratio in the CCA appears to be an additional parameter for predicting hemodynamically significant stenosis in patients with unilateral ICA stenosis.     

16层CT血管造影在诊断烟雾病中的应用价值

目的：探讨16层CT血管造影（16SCTA）在诊断烟雾病中的应用价值。方法23例烟雾病患者均行16层CT平扫和16SCTA检查,图像后处理采用多平面重组（MPR）、容积再现（VR）和最大密度投影（MIP）。其中5例同时行数字减影血管造影（DSA）检查。结果16层CT平扫显示脑梗死8例,脑出血7例,脑出血合并脑梗死6例,脑实质未见异常2例。16SCTA均清晰显示发生狭窄、闭塞的颈内动脉、Willis环血管近侧端,以及明显增多、扩张的脑底部侧支血管影,其中双侧颈内动脉闭塞8例,单侧大脑中动脉闭塞13例,单侧颈内动脉闭塞伴同侧大脑后动脉狭窄2例。侧支血管表现为相应血管及其分支的粗大、增多、迂曲。5例DSA表现与16SCTA结果一致。结论16SCTA可以清晰显示烟雾病病变血管的特点,检查方法简单、快捷,可为临床诊疗提供重要的诊断依据。     

Non-invasive assessment of the Circle of Willis using transcranial pulsed Doppler ultrasound with angiographic correlation.

The ability of transcranial pulsed Doppler ultrasound (TCD) to provide a dynamic assessment of the functional capability of the Circle of Willis was assessed using conventional cerebral angiography for anatomic correlation. Eleven patients had normal four-vessel cerebral angiography prior to being investigated with ultrasound. Angiography and ultrasound both demonstrated a functional anterior communicating artery in nine of the eleven patients, giving complete agreement between the two techniques. Posterior communicating arteries were visualized angiographically in all eleven patients. Ultrasound identified bilateral functional vessels in nine, the other two patients having non-functional vessels. In these latter two patients, angiography demonstrated three of the four posterior communicating arteries to be hypoplastic and it was uncertain whether these vessels carried significant blood flow. The fourth posterior communicating artery was shown to have an absent proximal segment of the ipsilateral posterior cerebral artery, with a persistent fetal posterior communicating artery. This anatomical variation is a potential limitation of ultrasound for assessing functional posterior communicating arteries. These preliminary results indicate that a combination of the anatomical (angiographic) and dynamic (ultrasonic) data may prove to be complementary for assessing the Circle of Willis.     

Poststenotic flow and intracranial hemodynamics in patients with carotid stenosis: transoral carotid ultrasonography study

BACKGROUND AND PURPOSE: In severe carotid stenosis, blood supply via the poststenotic internal carotid artery (ICA) and collateral pathways determine cerebral perfusion. We investigated whether poststenotic flow on transoral carotid ultrasonography (TOCU) is predictive of cerebral hemodynamics. METHODS: Eighty-eight patients with unilateral carotid stenosis underwent TOCU to analyze blood flow velocity and poststenotic diameter of the extracranial ICA. Intracranial collaterals and cerebral hemodynamics were assessed with selective angiography and single photon emission CT. RESULTS: Poststenotic diameter (P <.0001) and velocities (peak systolic velocity [PSV], time-averaged mean velocity [TMV], end-diastolic velocity [EDV]; all P < or = .009) decreased with stenotic severity. Poststenotic diameter was correlated with PSV (r=0.36, P=.0005), EDV (r=0.32, P=.002), and TMV (r=0.39, P=.0001). Poststenotic flow was significantly lower with collateral pathways than without pathways (P < or = .02) and significantly decreased as the number of the collaterals increased (P <.0001). Flow <5 mL/s indicated collaterals (81% sensitivity, 80% specificity). When flow was <5 mL/s, the asymmetry index in the middle cerebral artery (MCA) territory was significantly low during rest (P=.003) and after acetazolamide challenge (P=.006). Poststenotic flow velocity was associated with baseline (P=.007) and postacetazolamide (P=.0009) MCA asymmetry indexes. CONCLUSION: Poststenotic ICA flow measured with TOCU reflects collateral flow and cerebral hemodynamics in patients with severe carotid stenosis. This technique may provide new parameters for screening patients with hemodynamically significant carotid stenosis.     

A case of Horner syndrome with intermittent mydriasis in a patient with hypoplasia of the internal carotid artery

We report a rare case of hypoplasia of the right internal carotid artery (ICA) with ipsilateral congenital Horner syndrome. The etiology and pathogenesis of hypoplasia of the ICA is not well understood. Multiple types of collateral flow have been reported to develop to maintain blood supply to the ipsilateral cerebral hemisphere. Although collateral flow may allow these patients to remain asymptomatic, we postulate that the enlarged posterior communicating artery (PcomA) in our patient caused mass effect on the cisternal segment of cranial nerve III causing intermittent mydriasis apart from Horner syndrome.     

The suboccipital carrefour: cervical and vertebral arterial anastomosis.

PURPOSEOur objective was to anatomically define the anastomoses between cervical and carotid arterial distributions (the carrefour) in the rabbit and to assess the contribution of these collaterals to cortical blood flow (CBF) during cerebral ischemia.METHODSAngiography was carried out in six rabbits with basilar artery occlusion using selective contrast injection into the right subclavian, external carotid, and internal carotid arteries. Anastomoses were corroborated with methacrylate vascular casts prepared in five additional rabbits. CBF was measured in eight rabbits by H2 clearance after basilar artery occlusion and again after bilateral common carotid artery occlusion. Cortical DC potential was measured during ischemia in these rabbits and in another 19 rabbits after additional occlusion of the cervical collateral arteries.RESULTSA network of anastomoses between superficial and ascending cervical, superior intercostal, vertebral, and occipital arteries was found by angiography and corrosion casts. Additional communications in the ophthalmic, ethmoidal, and cerebellar arterial distributions are described. These pathways were found to supply a mean of 15 +/- 7 mL/100 g per minute residual CBF during three-vessel ischemia, or 24% of the preischemic CBF. Ischemic depolarization of DC potential occurred in seven of the eight rabbits with collateral CBF at a mean latency of 2.64 +/- 0.59 minutes and at 1.71 +/- 0.09 minutes in those without.CONCLUSIONThe suboccipital collateral network of the rabbit resembles that of humans and can contribute significantly to CBF during ischemia. The results suggest that this model may be useful for evaluating methods of optimizing hemodynamic control of the anastomoses in situations such as those encountered during endovascular therapy.     

Relationship between findings of conventional and contrast-enhanced transcranial color-coded real-time sonography and angiography in patients with basilar artery occlusion

BACKGROUND AND PURPOSE: Contrast-enhanced transcranial color-coded real-time sonography (TCCS) is a promising tool for the evaluation of brain circulation. The purpose of the present study was to assess the diagnostic ability of conventional and contrast-enhanced TCCS in patients with acute stroke and basilar artery occlusion and to compare the findings with those of angiography. METHODS: We prospectively performed conventional and contrast-enhanced TCCS within 3 days before or after digital subtraction angiography or MR angiography in 62 consecutive patients with acute ischemic stroke. We assigned the patients to two groups on the basis of angiographic findings: basilar artery occlusion group (n = 7) and control group without basilar artery occlusion (n = 55). We obtained basilar artery flow images showing the direction of blood flow using TCCS through a suboccipital window. RESULTS: In the control group, the detection rate of basilar artery flow using conventional and contrast-enhanced TCCS was 76.4% and 98.2%, respectively (P <.001), and the flow direction was antegrade in all patients. In the basilar artery occlusion group, neither conventional nor contrast-enhanced TCCS could obtain flow images of the proximal basilar artery in any patient. In five patients with proximal basilar artery occlusion, a reversed flow image in the distal basilar artery obtained by contrast-enhanced TCCS was confirmed by angiography to be blood supply through collateral circulation from the carotid systems. However, two patients with distal basilar artery occlusion did not have this sign. CONCLUSION: Contrast-enhanced TCCS is more sensitive in imaging basilar artery flow than is conventional TCCS. When examined with contrast-enhanced TCCS, a combination of absent basilar artery flow and the reversed basilar artery flow sign may be a diagnostic indicator of basilar artery occlusion.     

后交通动脉变异的MRA研究及其与后循环梗死的相关性

后循环脑梗死日益引起临床的关注。部分后循环脑梗死病人病灶与供血动脉病变不匹配,或血管狭窄的影像表现与临床表现不匹配,提示血管解剖变异或侧支循环影响了脑血流分配代偿。后交通动脉是后循环最重要的侧支动脉,可沟通前后循环的血流,但其常因变异而影响血流代偿,与后循环脑梗死的发生、转归有关。目前有多种磁共振血管成像(MRA)技术可应用于后交通动脉的检查,是活体研究后交通动脉的重要手段。就后交通动脉的MRA以及后交通动脉与后循环脑梗死相关性的研究进行综述,为临床应用MRA筛选潜在高危后循环梗死病人提供参考。     

经颅多普勒对颈内动脉颅外段重度狭窄或闭塞的颅内血流动力学分析

目的研究经颅多普勒超声（TCD）对颈内动脉颅外段重度狭窄或闭塞后颅内血流动力学参数的变化，探讨其临床应用价值。方法对32例经TCD诊断为颈内动脉颅外段重度狭窄或闭塞患者，分析其双侧大脑中动脉（MCA）、大脑前动脉（ACA）、大脑后动脉（PCA）的收缩期峰值流速（PSV）及血管搏动指数（P1），判断侧支循环开放类型，并以30例正常体检人群作为对照组，所得结果进行统计学分析。结果一侧颈内动脉颅外段重度狭窄或闭塞后，其颅内血流参数与正常对照组比较，存在明显的不对称性，经统计学t检验，差异有显著意义。TCD检测侧支循环开放例数与DSA比较，经统计学X^2检验，二者无差异（P〉0．05）。结论TCD能准确地检测到颈内动脉颅外段重度狭窄或闭塞后颅内血流动力学的变化，为临床选择治疗方法及判断预后提供有价值的信息。