Sequential change of hemodynamic reserve in patients with major cerebral artery occlusion or severe stenosis

Summary To identify regional vasodilatory capacity and its sequential change, we evaluated prospectively a total of 78 acetazolamide tests in 51 patients with occlusion or greater than 75% stenosis of the carotid or middle cerebral arteries. The relative distribution of cerebral blood flow was determined by single photon emission computed tomography usingN-isopropyl-p-[¹²³I]-iodoamphetamine before and after intravenous injection of acetazolamide. Reduced vasodilatory capacity was demonstrated in 20 patients (38%), including 5 patients with hemodynamic transient ischemic attacks or infarction. Follow-up acetazolamide tests revealed asymptomatic progression of the arterial lesion (from stenosis to occlusion) in 1 patient and almost complete improvement of vasodilatory capacity in 5 patients, including 3 without surgical intervention. During an average follow-up period of 18.5 months, 4 patients died from cardiac causes or neoplasm; no neurovascular events occurred. Much larger numbers of patients with longer observation periods will be necessary to clarify the contribution of chronic hemodynamic failure to subsequent stroke. However, the present data indicate that the acetazolamide test is useful for assesssing the course of high grade stenosis or occlusion of major cerebral arteries.     

Assessment of cerebral haemodynamics and vascular reserve in patients with symptomatic carotid artery occlusion: an integrated MR method

We describe an MR-based methodology designed to study cerebral haemodynamic compromise in patients with symptomatic carotid occlusions. We present the results of eight patients who underwent MR angiography of the cervical carotids and circle of Willis, MR imaging of the brain and dynamic gadolinium MR perfusion studies before and after the injection of the carbonic anhydrase inhibitor acetazolamide. All patients showed increased transit times in the symptomatic hemisphere at rest indicating reduced flow. The transit time asymmetries became more pronounced after acetazolamide in all patients because of failed vasodilatation on the affected side. There was an inverse correlation between the degree of increased transit time and the degree of collateralisation around the circle of Willis. We believe that demonstration of both macroscopic vascular anatomy and microvascular reserve is important when assessing patients with possible low-flow states and the described method is a robust means of obtaining that data.     

Cerebral hemodynamics in asymptomatic patients with internal carotid artery occlusion: a dynamic susceptibility contrast MR and transcranial Doppler study.

BACKGROUND AND PURPOSE: Perfusion imaging with dynamic susceptibility contrast MR imaging (DSC-MRI) has been used to evaluate hemodynamic status in patients with symptomatic occlusive cerebrovascular disease. The aim of the present study was to determine the hemodynamic changes occurring in asymptomatic patients with unilateral internal carotid artery (ICA) occlusion by use of DSC-MRI with transcranial Doppler (TCD) measurement of the breath-holding index (BHI). METHODS: Nine patients with asymptomatic unilateral ICA occlusion underwent DSC-MRI and TCD examination. One patient was excluded from final analysis because of severe movement artifacts. On a separate workstation, regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and regional mean time to peak (rMTT) were calculated on the basis of signal decay rate during the passage of gadolinium bolus through the sampled volume in the territory of the middle cerebral artery. TCD-BHI was calculated in all patients. Six healthy subjects underwent the same MR protocol as the patients. RESULTS: Compared with control subjects, patients with unilateral ICA occlusions had hemodynamic changes in the ipsilateral hemisphere: rCBF was significantly lower than in controls (P <.01), and r MTT was significantly increased in both white (WM) and gray matter (GM) in the affected side (WM: P <.01; GM: P <.05). No statistically significant difference in rCBV was found in the group of patients (occluded versus contralateral, P <.1) or between the patient and control groups (occluded side versus controls, P <.1). The correlation of rCBV and BHI showed a strong relation of the two variables, showing a decrease of the latter when the former increased. CONCLUSION: DSC-MRI is a valuable tool for measuring hemodynamic changes in the presence of carotid disease with hemodynamic impairment. In our opinion, hemodynamic changes and efficiency of collateral pathways can be evaluated in occlusive carotid disease by using paired measurement of BHI and DSC-MRI. In the patient group, MR-determined rCBV and TCD-determined BHI showed a significant inverse correlation, suggesting similar significance of the two indices.     

Changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery

Purpose

To evaluate changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery in the patients who underwent ischemic stroke caused by carotid artery stenosis.

Methods

Twenty patients with unilateral symptomatic carotid artery stenosis received brain computer tomography perfusion (CTP) scan a week before and a week after carotid artery stenting. Three absolute values including mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were acquired and analyzed by use of the post-processing software. Six vascular territories such as ACA territory, MCA territory, PCA territory, basal ganglia, watershed between ACA and MCA territory (frontal watershed), watershed between MCA and PCA territory (posterior watershed) were chosen for comparison. Relative parameter values were defined as rCBF (relative CBF), rCBV (relative CBV), rMTT (relative MTT) through comparing absolute values in symptomatic hemispheres to absolute values in asymptomatic hemispheres. The relative perfusion parameter values before treatment were compared with post-treatment values. These analyses were performed by using the paired t test.

Results

The mean rMTT decreased significantly in ACA territory, MCA territory and two watershed after treatment, while the mean rCBF increased significantly in those areas after treatment. But the mean rCBV had no significant changes in all six vascular territories. In PCA territory, all the parameters had no significant changes.

Conclusion

Carotid artery stenting yields satisfactory cerebral perfusion in ACA territory, MCA territory, basal ganglia and two watersheds.     

Proton magnetic resonance spectroscopy in patients with symptomatic unilateral internal carotid artery / middle cerebral artery stenosis or occlusion

Purpose:

To explore the value of proton magnetic resonance spectroscopy imaging (¹H‐MRSI) in patients with stenosis or occlusion of the internal carotid artery (ICA) / middle cerebral artery (MCA).

Materials and Methods:

Fifty noninfarcted patients with stenosis or occlusion of unilateral ICA/MCA were included in our study. In the meantime, 25 patients with cerebral infarction and 25 healthy control subjects were enrolled. All patients and healthy control subjects underwent ¹H‐MRSI. Cerebral metabolic changes were studied in the noninfarcted patients and compared with the infarcted patients as well as healthy control subjects.

Results:

In 50 noninfarcted patients N‐acetylaspartate (NAA) decreased and choline increased in the ischemic hemisphere compared with the contralateral side and control subjects. Lactate peaks were observed in 12 patients. The metabolic changes were relatively slight but were associated with metabolic disruption in infarcted patients. There were relationships between metabolic abnormalities and neurological status of the noninfarcted patients.

Conclusion:

¹H‐MRSI can demonstrate abnormal metabolic changes in cerebral tissues with no infarction, while with ICA/MCA may show stenosis or occlusion at an early stage, which may help guide treatment decisions and preoperative evaluation. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Dynamic susceptibility contrast perfusion magnetic resonance imaging in patients with symptomatic unilateral middle cerebral artery stenosis or occlusion

PURPOSE: To evaluate cerebral hemodynamic disturbance in patients with symptomatic unilateral middle cerebral artery (MCA) high-grade stenosis or occlusion using dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-pMRI). MATERIAL AND METHODS: DSC-pMRI was performed in 28 patients with symptomatic unilateral MCA high-grade stenosis or occlusion. Hemodynamic parameters including relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transit time (rMTT), and time to peak (TTP) were calculated and compared between the stenosed or occluded side and contralateral side. Seven of the 28 patients underwent surgery or interventional therapy, and hemodynamic changes between pre- and post-therapy were investigated. RESULTS: Prolonged rMTT and TTP were found in the stenosed or occluded MCA territories in all 28 patients. Significant differences were found in rCBV (P<0.05), rMTT (P<0.001), and TTP (P<0.001) between the stenosed or occluded side and the contralateral side. However, no significant difference was observed in rCBF (P>0.05). In the seven patients with surgical or interventional therapy, the values of rMTT and TTP significantly decreased after surgery or interventional therapy (P<0.001). CONCLUSION: DSC-pMRI may be a useful tool for evaluating and monitoring cerebral hemodynamic disturbance in patients with symptomatic unilateral MCA high-grade stenosis or occlusion.     

Long-term results of symptomatic fibroids treated with uterine artery embolization: In conjunction with MR evaluation

Objective

The aim of the present study is to determine long-term clinical efficacy of uterine fibroid embolization (UFE) for symptomatic fibroids in conjunction with MR evaluation.

Materials and methods

Sixteen patients with a follow-up period of 4 years or longer were analyzed retrospectively. Ages ranged from 27 to 45 (mean 39.5) years. Mean follow-up periods were 5.8 years (range: 4.1-6.9 years). The symptom changes, in terms of menorrhagia and dysmenorrhea and bulk-related symptoms, were assessed. The primary embolic agent was polyvinyl alcohol particle (250-710 μm). All patients underwent preprocedural and long-term follow up MR imaging. Uterine volumes were calculated using MRI.

Results

Symptom improvements were reported for menorrhagia (8/9, 88.9%), dysmenorrhea (5/5, 100%), and bulk-related symptoms (7/9, 77.8%) at long-term follow up. Two patients (12.5%) had symptom recurrences at long-term follow-up. Tumor regrowth from incomplete infarction was a cause of recurrence in one patient and newly developed leiomyomas in the other one.One patient underwent hysterectomy because endometriosis developed 4 years after UFE.Of the 14 necrotic myomas on short-term follow up MR after UFE, eight (57.1%) demonstrated maintaining necrosis with further shrinkage and six (42.9%) were no longer visualized on long-term follow up MR images. Overall, the mean volume reduction rates of the predominant fibroid and uterus were 80.5%, 36.7% at long-term follow up, respectively.

Conclusion

UFE is an effective treatment for symptomatic fibroids with an acceptable long-term success rate. Long-term MR imaging after UFE revealed persistent necrotic fibroid, non-visualization of fibroids and tumor regrowth when incompletely infarcted.     

High resolution MR imaging in patients with symptomatic middle cerebral artery stenosis

Purpose

High resolution magnetic resonance imaging (HRMRI) has been used as an imaging modality to depict the intracranial artery wall. The aim of this study was to compare images of the vessel wall between symptomatic and asymptomatic atherosclerotic plaques of the middle cerebral artery (MCA) using HRMRI.

Materials and methods

From September 2009 to August 2010 we prospectively screened consecutive patients for MCA stenosis using time-of-flight (TOF) MR angiography. We studied 14 patients with symptomatic MCA stenosis and 16 patients with asymptomatic MCA stenosis. The HRMRI protocol included three different scans: T1-, T2-, and proton density (PD)-weighted black blood MRI. The cross-sectional images of the MCA wall on HRMRI were compared between the two groups based on the degree of stenosis, remodeling ratio, outward or inward remodeling, plaque signal intensity, plaque surface irregularity, and presence of an intact inner wall.

Results

The degree of MCA stenosis and the ratio of plaque thickening to patent lumen in the symptomatic group were significantly higher than in the asymptomatic group. Outward remodeling of the stenotic area in symptomatic group was significantly higher than that seen in the asymptomatic group, and the reverse was true for inward remodeling of the stenotic area (it was significantly higher in the asymptomatic group compared to the symptomatic group). T2- and PD-weighted high signal foci, eccentric wall thickening, and plaque volume in the stenotic area were all similar between the two groups.

Conclusions

HRMRI has the potential to distinguish between atherosclerotic plaques in symptomatic and asymptomatic MCA stenoses.     

Effect of calcium antagonist on cerebral blood flow and oxygen metabolism in patients with hypertension and chronic major cerebral artery occlusion: a positron emission tomography study

To evaluate the effect of a calcium antagonist, nilvadipine, on cerebral blood flow and oxygen metabolism, we prospectively examined five ischaemic stroke patients, with both hypertension and chronic major cerebral artery occlusion, using positron emission tomography. The blood pressure showed a significant decrease after 3 months of nilvadipine treatment, the cerebral blood flow in the affected regions showed a significant increase and the oxygen extraction fraction showed a significant decrease. We conclude that nilvadipine is a safe and effective anti-hypertensive agent for patients with both hypertension and chronic major cerebral artery occlusion.     

飞行人员无症状性脑梗死的初步随访观察

目的 观察无症状性脑梗死(ACI)飞行人员的短期预后.方法 随访经头颅核磁共振检查(MRI)诊断为ACI的22例飞行人员,观察ACI病灶的数量、急性症状性脑血管事件及任何原因停飞的发生情况,比较病灶增加者与未增加者ACI危险因素的差异.结果 22例ACI飞行人员随访6～42(14.18±8.55)个月,其中6例(18.18％)复查后病灶增多.所有随访人员均无神经功能缺损事件发生,3例非ACI原因停止飞行.病灶增加者与未增加者的年龄、飞行时间比较差异有统计学意义(P＜0.05).结论 部分飞行人员ACI病灶数目会增多,可能与年龄、飞行时间等有关,其远期对飞行的影响需进一步研究.     

Evaluation of crossed cerebellar diaschisis in 30 patients with major cerebral artery occlusion by means of quantitative I-123 IMP SPECT

Quantitative crossed cerebellar diaschisis (CCD) and the correlation with a reduction in supratentorial regional cerebral blood flow (rCBF) and cerebrovascular reserve capacity (CVR) were investigated in clinically stable patients with major cerebral artery occlusion by the iodine-123-N-isopropyl-p-iodoamphetamine (I-123 IMP) single photon emission computed tomography (SPECT) method. Thirty patients with major cerebral artery occlusion underwent SPECT by the I-123 IMP autoradiographic method. Regional CBF was measured in the cerebral hemisphere, frontal and parietal lobes, temporo-parietal lobe, and cerebellum both at rest and after administration of acetazolamide. Eighteen of 30 patients (60%) had CCD. CCD was significantly related to magnetic resonance imaging evidence of infarction. Quantitative CCD was 17% and the CVR in the cerebellum was preserved in patients with CCD. There was a significant difference in CBF and CVR between the affected and normal sides in all regions of interest in the patients without CCD [CBF (ml/100 g/min): hemisphere (H), normal side (N): 31.4 +/- 6.8, affected side (A): 27.5 +/- 7.4; p < 0.05. CVR: H, N: 0.56 +/- 0.38, A: 0.42 +/- 0.18; p < 0.01]. CCD is common in patients with major cerebral artery occlusion, and quantitative I-123 IMP SPECT is helpful in detecting CCD in clinically stable patients with occlusion of major cerebral arteries.     

Transcranial Doppler ultrasound in the evaluation of collateral blood flow in patients with internal carotid artery occlusion: correlation with cerebral angiography.

PURPOSETo determine the accuracy of transcranial Doppler (TCD) ultrasound for evaluation of collateral supply through the circle of Willis in patients with internal carotid artery (ICA) occlusion.METHODSThe evaluation of the collateral pathways through the circle of Willis with TCD ultrasound and with cerebral angiography was compared in 40 patients (30 men, 10 women; mean age, 55 +/- 9 years) in a total of 44 ICA occlusions of which 43 had a suitable ipsilateral temporal bone window for TCD examination.RESULTSBy TCD, a patent anterior communicating artery is indicated by a reversal blood flow in the A1-segment of the anterior cerebral artery or by a prompt fall of blood velocity in the middle cerebral artery after compression of the nonoccluded contralateral carotid artery. In 42 of 43 instances of ICA occlusion, TCD and angiography agreed in the evaluation of a present or absent anterior communicating artery collateral supply. TCD''s sensitivity was 95%, its specificity 100%. A collateral supply through the basilar artery was assumed with TCD when there was: (a) a basilar artery blood velocity of more than 70 cm/s; (b) a marked increase of basilar artery blood velocity after compression of the nonoccluded carotid artery; (c) an evident side-to-side asymmetry of the blood velocity of the posterior cerebral arteries with high blood velocity ipsilateral to the ICA occlusion. For evaluating the collateralization via the basilar artery, TCD and angiography agreed in 37 of 40 ICA occlusions. TCD''s sensitivity was 87%, its specificity 95%.CONCLUSIONSTCD is a reliable tool for the evaluation of the collateral supply in patients with ICA occlusions.     

症状性颅内动脉狭窄介入治疗前的影像评估

目的 探讨症状性颅内动脉狭窄介入治疗前影像评估对介入治疗适应证选择的指导价值.方法 26例颅内动脉狭窄患者,介入治疗前全部行DSA、高分辨率MRI斑块成像、CT或MR灌注成像,分别对脑供血动脉、动脉狭窄程度和斑块性质及成分、脑血流灌注情况等进行评价.对动脉粥样硬化性狭窄的患者,根据高分辨MRI表现分析斑块性质,对不稳定性斑块患者行介入治疗;而对动脉炎性狭窄的患者则采用药物治疗.随访观察有无再发缺血性脑卒中事件.结果 18例患者MRI表现为血管偏心狭窄、病灶轻度强化或不强化,DSA表现为Mori B型或C型病变,判断狭窄由动脉粥样硬化斑块引起.这18例中13例为不稳定斑块;1例为稳定斑块伴灌注失代偿,给予颅内支架成形术;其余4例稳定斑块引起狭窄患者采用药物治疗.8例狭窄由动脉炎引起,MRI显示狭窄病变处内膜向心性增厚和环形强化,采取内科保守治疗.本组患者随访1.0～8.0个月,中位时间6.0个月,平均(5.2±3.1)个月,未再出现狭窄病变相关性短暂性脑缺血发作(TIA)或脑卒中.结论 症状性颅内动脉狭窄患者治疗前进行综合影像评估,对于指导临床制定治疗方案具有重要价值.     

Is local intra-arterial fibrinolysis contraindicated in elderly patients with cerebral artery occlusion?

Local intra-arterial fibrinolysis (LIF) is an effective treatment for selected patients in acute thromboembolic occlusion of the middle cerebral artery, vertebrobasilar system or ophthalmic artery. However, the risk/benefit ratio of thrombolysis in patient subgroups requires classification. Advanced age has been regarded as a prognostic factor for poor clinical outcome. We report our experience with LIF in seven patients with a mean age of 79 years (range 76–83 years) who represented thromboembolic occlusion of the basilar, middle cerebral or pericallosal arteries. We discuss why advanced age need not contraindicate LIF. Received: 26 October 1997 Accepted: 29 April 1998     

Schizencephaly with occlusion or absence of middle cerebral artery

In a study of 160 infants with prenatal and/or perinatal risk factors for brain damage, we observed three cases of schizencephaly. All cases were unilateral, and the clefts had open lips. In two cases, magnetic resonance angiography showed occlusion or absence of the middle cerebral artery (MCA) on the affected side. Two of the patients, including one with absent flow in the MCA of the affected side, had ipsilateral cerebellar atrophy.     

Predictors of clinical outcome in patients receiving local intra-arterial thrombolysis without subsequent symptomatic intracranial hemorrhage against acute middle cerebral artery occlusion

BACKGROUND AND PURPOSE: The factors that predict favorable outcome after local intra-arterial thrombolysis (LIT) remain unknown. We aimed to clarify these factors in patients with middle cerebral artery occlusion treated by LIT. METHODS: We performed LIT in 26 consecutive patients who had middle cerebral artery occlusion with a modified Rankin scale (mRS) score or=3). RESULTS: The duration from symptom onset to hospital admission was 0.96 +/- 0.87 (mean +/- SD) hour and from onset of stroke to LIT was 3.78 +/- 1.17 hours. No patients developed symptomatic intracerebral hemorrhage or died. Thirteen patients achieved good outcomes. No significant differences existed between the two groups in baseline National Institutes of Health Stroke Scale (NIHSS) scores, time from stroke onset to LIT, blood pressure, early CT signs, or subsequent hemorrhagic transformation shown by CT. However, univariate analysis showed that patients with good outcomes were younger, more often had absence of hypertension history, had better collaterals shown by angiography, and had better recanalization rates than those with poor outcomes. NIHSS scores after LIT were lower in patients with good outcomes than in patients with poor outcomes. Logistic regression analysis indicated improvement of the NIHSS scores by >or=2 immediately after LIT was independently associated with good outcome. CONCLUSION: Improvement of the NIHSS score by >or=2 immediately after LIT is a useful predictor of patient outcome at discharge.