Dual- versus Single-Energy CT-Angiography Imaging for Patients Undergoing Intracranial Aneurysm Repair

BACKGROUND

The invasiveness and risk of thromboembolic complications of catheter angiography underline the need for alternative imaging modalities in patients following intracranial aneurysm (IA) repair. However, the overall image quality of existing noninvasive imaging modalities, such as single-energy CT angiography (SE-CTA), compromises its value in this respect.

OBJECTIVE

We prospectively investigated the value of a novel dual-energy CTA (DE-CTA) scanner and algorithm for assessing the degree of occlusion and parent vessel patency in patients following IA repair.

METHODS

A prospective cohort of 17 patients underwent DE-CTA imaging following surgical or endovascular IA repair. This dataset was matched with an identical historical cohort of 17 patients, who underwent IA repair and SE-CTA imaging. Beam-hardening artifacts, as a measure for objective imaging quality were analyzed based on the volume of a prolate ellipsoid, whereas subjective imaging quality at the IA site and corresponding parent vessels was rated by 2 independent neuroradiologists on a scale from 4 (excellent, no artifacts) to 1 (poor, severe artifacts).

RESULTS

Objective DE-CTA image quality was markedly higher, compared to SE-CTA in patients undergoing surgical (0.77 ± 0.23 vs. 10.91 ± 1.88 mL, respectively; p < 0.001) or endovascular (32.36 ± 10.62 vs. 107.63 ± 24.51 mL, respectively; p = 0.026) IA repair. Subjective image quality for DE-CTA was significantly improved compared to SE-CTA in the surgical group but not in the endovascular group. The calculated dose values for DE-CTA in our study remain markedly below the legally required radiation dose limits.

CONCLUSION

The imaging quality of DE-CTA, especially for patients undergoing surgical IA repair, is distinctly superior, compared to SE-CTA imaging. Therefore, DE-CTA may serve as a noninvasive alternative for assessing the IA occlusion rate and parent vessel patency.

Outcome and Treatment Effects in Stroke Associated with Acute Cervical ICA Occlusion

Background

Endovascular therapy (EVT) with stent retrievers in addition to i.v. thrombolysis (IVT) has proven effective in acute stroke patients with middle cerebral artery (MCA, M1 segment) and distal internal carotid artery (ICA) occlusion. Limited data exist concerning acute cervical ICA occlusion, either alone or in combination with intracranial ICA occlusion (tandem occlusion). Therefore we analyzed outcome and treatment effects in stroke associated with cervical ICA occlusion, with specific focus on the impact of intracranial ICA or M1 patency.

Methods

Seventy-eight patients with cervical ICA occlusion from our local stroke unit registry were analyzed retrospectively. Thrombolysis in Cerebral Infarction (TICI) classification, infarct size, modified Rankin scale (mRS), symptomatic intracerebral hemorrhage (ICH), and death were assessed as outcome parameters.

Results

Forty-three patients had isolated cervical ICA occlusion whereas 35 patients presented with extra-/intracranial tandem occlusion. Patients underwent IVT alone (n = 23), combined IVT/EVT (n = 28) or no treatment (n = 27). Treated and untreated patients with tandem occlusion had a worse outcome after 90 days compared to isolated cervical occlusion (OR for moderate outcome 0.29, 0.27–0.88, p = 0.01). Additional EVT improved outcome in patients with tandem occlusion (OR for moderate outcome: 15.43, 1.60–148.90, p = 0.008) but not isolated cervical occlusion (OR 1.33, 0.38–11.60, NS).

Conclusions

In contrast to tandem occlusion, stroke outcome in patients with isolated cervical ICA occlusion was generally more benign and not improved by combined IVT/EVT compared to IVT alone. Intracranial vessel patency may be critical for treatment decision in acute cervical ICA occlusion.

Safety of endovascular treatment in acute stroke patients taking oral anticoagulants

Background

The endovascular treatment of acute cerebral ischemia has been proven beneficial without major safety concerns. To date, the role of endovascular treatment in patients treated with oral anticoagulants, which may be associated with periprocedural intracranial bleeding, remains uncertain.

Aims

The objective of the current analysis is to evaluate the safety of endovascular treatment in patients treated with oral anticoagulants.

Methods

The ENDOSTROKE-Registry is a commercially independent, prospective observational study in 12 stroke centers in Germany and Austria collecting pre-specified variables about endovascular stroke therapy.

Results

Data from 815 patients (median age 70 (interquartile range (IQR) 20), 57% male) undergoing endovascular treatment with known anticoagulation status were analyzed. A total of 85 (median age 76 (IQR 8), 52% male) patients (10.4%) took vitamin-K-antagonists prior to endovascular treatment. Anticoagulation status as measured with international normalized ratio was above 2.0 in 31 patients. Intracranial hemorrhage occurred in 11.8% of patients taking vitamin-K-antagonists compared to no-vitamin-K-antagonists (12.2%, p = 0.909). After adjustment for confounding factors which were unbalanced at univariate level such as NIHSS and age, anticoagulation status was not found to significantly influence clinical outcome (modified Rankin Scale 3–6) and occurrence of intracranial hemorrhage in a multivariate logistic regression analysis.

Conclusion

Prior use of vitamin-K-antagonists was not associated with a higher rate of periprocedural intracranial hemorrhage after endovascular treatment or worse outcome. Endovascular treatment should be considered as an important treatment option in patients taking vitamin-K-antagonists.

Abstract TP9: Safety of Endovascular Treatment in Acute Stroke Patients Taking Oral Anticoagulants

Introduction: The endovascular treatment (EVT) of cerebral ischemia in the case of large vessel occlusion has been established over recent years. Randomized trials showed a positive impact on the clinical outcome of endovascular treatment in addition to thrombolysis with respect to clinical outcome and safety, so that this therapeutic option will be implemented in future guidelines. The role of EVT in patients treated with oral anticoagulants remains uncertain.

Hypothesis: We assessed the hypothesis that application of EVT is safe with regard to the occurrence of intracranial bleeding and clinical outcome in patients taking anticoagulants.

Methods: The ENDOSTROKE-Registry is a commercially independent, prospective observational study in 12 stroke centers in Germany and Austria launched in January 2011. An online tool served for data acquisition of pre-specified variables concerning endovascular stroke therapy.

Results: Data from 815 patients (median age 70, 57% male) undergoing EVT and known anticoagulation status were analyzed. A total of 85 (median age 76, 52% male) patients (10.4%) took oral anticoagulants prior to EVT. Anticoagulation status as measured with INR was 2.0-3.0 in 24 patients (29%), <2.0 in 52 patients (63%) and above 3.0 in 7 patients (8%) of 83 patients with valid INR data prior to EVT. Patients taking anticoagulants were significantly older (median age 76 vs. 69, p < 0.001). Comparing those patients taking anticoagulants and those not, there were no differences concerning NIHSS at admission (with anticoagulants Median-NIHSS 17 vs. without Median-NIHSS 15, p = 0.492, Mann Whitney Test) and the rate of intracranial hemorrhage after intervention (with anticoagulants 11.8% vs. without 12.2%, p = 0.538). After adjustment for age and NIHSS at admission there were no significant differences between the two groups with regard to good clinical outcome, as measured with the modified ranking scale (mRS, 90d-mRS 0-2, 39.2% of patients not receiving anticoagulants; 25.9% of those receiving anticoagulants).

Conclusion: The application of endovascular treatment in patients taking oral anticoagulants is safe and should be considered in acute stroke treatment as an important alternative to contraindicated intravenous thrombolysis.

Functional Connectivity Differences of the Subthalamic Nucleus Related to Parkinson's Disease

A typical feature of Parkinson's disease (PD) is pathological activity in the subthalamic nucleus (STN). Here, we tested whether in patients with PD under dopaminergic treatment functional connectivity of the STN differs from healthy controls (HC) and whether some brain regions show (anti-) correlations between functional connectivity with STN and motor symptoms. We used functional magnetic resonance imaging to investigate whole-brain resting-state functional connectivity with STN in 54 patients with PD and 55 HC matched for age, gender, and within-scanner motion. Compared to HC, we found attenuated negative STN-coupling with Crus I of the right cerebellum and with right ventromedial prefrontal regions in patients with PD. Furthermore, we observed enhanced negative STN-coupling with bilateral intraparietal sulcus/superior parietal cortex, right sensorimotor, right premotor, and left visual cortex compared to HC. Finally, we found a decline in positive STN-coupling with the left insula related to severity of motor symptoms and a decline of inter-hemispheric functional connectivity between left and right STN with progression of PD-related motor symptoms. Motor symptom related uncoupling of the insula, a key region in the saliency network and for executive function, from the STN might be associated with well-known executive dysfunction in PD. Moreover, uncoupling between insula and STN might also induce an insufficient setting of thresholds for the discrimination between relevant and irrelevant salient environmental stimuli, explaining observations of disturbed response control in PD. In sum, motor symptoms in PD are associated with a reduced coupling between STN and a key region for executive function.

Early postoperative magnet resonance tomography after resection of cerebral metastases

BACKGROUND

In contrast to malignant gliomas, the impact of an early postoperative MRI after surgery of cerebral metastasis is still unclear. The present study analyses early MRI-based postoperative resection controls and incidence of in-brain progression in 116 patients suffering from 130 cerebral metastases.

METHODS

The extent of surgical resection was verified by an early postoperative contrast-enhanced 1.5-T MRI within 72 h after surgery of cerebral metastases and correlated with in-brain progression, leptomeningeal carcinomatosis, and progression-free survival.

RESULTS

MRI confirmed complete resection was seen in 80 out of 130 metastases (61.5 %). In 24 metastases (18.5 %), no final decision on degree of resection could be made. Residual tumor was seen in 26 cases (20 %). Local in-brain progression was observed in 40 of 130 (30.8 %) cases. The incidence of in-brain progression significantly correlated with dural contact of the metastasis (p < 0.05) and residual tumor on early postoperative MRI (p < 0.0001). The odds ratio for local recurrence with residual tumor is 8.2-fold compared to no residual tumor.

CONCLUSIONS

Residual tumor after metastasis extirpation was shown in nearly 20 % of patients by an early postoperative MRI and significantly correlated with local in-brain progression. Furthermore, dural contact of cerebral metastases was identified as a risk factor for local recurrence. Further studies are mandatory to clearly identify the incidence of incomplete resections of cerebral metastases and their oncologic impact. An early postoperative MRI after resection of cerebral metastases is recommended as residual tumor promotes local recurrence.

An Appeal to Standardize CT- and MR-Perfusion

Multiple treatment options and risk assessment in cerebrovascular diseases are the actual challenges in diagnostic as well as in interventional neuroradiology.Acute ischemic stroke essentially requires rapid detection of the location and extent of infarction and tissue at risk for making treatment decisions. In the acute setting, modern multiparametric perfusion imaging protocols help to determine infarct core and adjacent penumbral tissue, and they enable the estimation of collateral flow of intra- and extracranial arteries. In subacute delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) or chronic occlusive neurovascular diseases estimation of residual and collateral flow may be even more difficult.Prediction of sufficient or insufficient supply of brain tissue may be essential to balance conservative against interventional therapies. However, so far no established reliable thresholds are available for determining tissue at acute, subacute, chronic progressive, or chronic risk.Reliable and reproducible thresholds require quantitative perfusion measurements with a calibrated instrument. But the measurement instrument is not at all defined-a variety of parameter settings, different algorithms based on multiple assumptions and a wide variety of published normal and pathologic values for perfusion parameters indicate the problem. In the following text, we explain how deep the problem may be enrooted within techniques and algorithms impeding broad use of perfusion for many clinical issues.

Endovascular stroke therapy with the Aperio thrombectomy device

BACKGROUND

The pharmaceutical therapy for acute ischemic stroke has shortcomings in reopening large vessels and dissolving long thrombi, and endovascular treatment has been found to provide added value. The Aperio thrombectomy device showed promising results in an experimental study. The purpose of this study was to evaluate the device clinically.

METHODS

119 patients with acute stroke were treated in nine centers using the Aperio thrombectomy device. Target vessel, diameter, thrombus length, procedure time, recanalization, number of deployments, additional use of anticoagulants, complications, and the use of additional devices were assessed.

RESULTS

The median thrombus length was 15 mm (range 1.5-20 mm) and the average time from device insertion to recanalization was 30 min (range 5-120 min). Blood flow restoration (Thrombolysis In Cerebral Infarction (TICI) 2-3) was achieved in 85%. In the majority of cases complete clot removal was achieved (TICI 0, 12%; TICI 1, 2%; TICI 2a, 14%; TICI 2b, 18%; TICI 3, 53%). The median number of deployments was 2 (range 1-6). Twelve procedural complications (10%) occurred.

CONCLUSIONS

The Aperio thrombectomy device seems to be an effective and adequately safe tool for reopening occluded cerebral arteries in the setting of acute stroke.

The influence of decompressive craniectomy for major stroke on early cerebral perfusion

OBJECT

Multiple trials have shown improved survival and functional outcome in patients treated with decompressive craniectomy (DC) for brain swelling following major stroke. It has been assumed that decompression induces an improvement in cerebral perfusion. This observational study directly measured cerebral perfusion before and after decompression.

METHODS

Sixteen patients were prospectively examined with perfusion CT within 6 hours prior to surgery and 12 hours after surgery. Preoperative and postoperative perfusion measurements were compared and correlated.

RESULTS

Following DC there was a significant increase in cerebral blood flow in all measured territories and additionally an increase in cerebral blood volume in the penumbra (p = 0.03). These changes spread as far as the contralateral hemisphere. No significant changes in mean transit time or Tmax (time-to-peak residue function) were observed.

CONCLUSIONS

The presurgical perfusion abnormalities likely reflected local pressure-induced hypoperfusion with impaired autoregulation. The improvement in perfusion after decompression implied an increase in perfusion pressure, likely linked to partial restoration of autoregulation. The increase in perfusion that was observed might partially be responsible for improved clinical outcome following decompressive surgery for major stroke. The predictive value of perfusion CT on outcome needs to be evaluated in larger trials.

Emerging tumefactive multiple sclerosis after switching therapy from natalizumab to fingolimod

In this report we describe a multiple sclerosis patient who developed a relapse with magnetic resonance imaging (MRI) features of tumefactive demyelination after switching therapy from natalizumab to fingolimod. Tumefactive lesions emerged 16 weeks after stopping natalizumab and eight weeks after commencing fingolimod therapy but had been absent at the time of diagnosis and throughout the preceding course of the disease. Thus, the first-time occurrence of atypical lesion features may have been caused by the change in immunotherapy. The possible relevance of natalizumab withdrawal vs fingolimod introduction is discussed against the background of recently published case studies.

Timing of Mean Transit Time Maximization is Associated with Neurological Outcome After Subarachnoid Hemorrhage

PURPOSE

Computed tomography perfusion (CTP) has gained significant relevance for the radiological screening of patients at risk of developing delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Particularly, the impact of MTT_PEAK, i.e., the maximal mean transit time value in a series of CTP measurements, for the prediction of long-term outcome has recently been demonstrated by our group. Complementing this recent work, the present study investigated how the timing of MTT_PEAK affected the long-term outcome after aneurysmal subarachnoid hemorrhage.

METHODS

CTP examinations from 103 patients with clinical deterioration attributed to DCI after aSAH were retrospectively analyzed for time interval between SAH ictus and onset of MTT_PEAK in association with modified Rankin Scale (mRS) 23.1 months after SAH.

RESULTS

Patients with unfavorable outcome (mRS > = 2) suffered significant earlier MTT_PEAK onsets than patients with favorable outcome (mRS = 0 and 1). MTT_PEAK within the first week was associated with significantly higher mRS scores compared to later MTT_PEAK. Timing of MTT_PEAK together with the value of MTT_PEAK and initial World Federation of Neurosurgical Societies (WFNS) grade was a significant predictor for an unfavorable outcome (mRS > = 2).

CONCLUSIONS

The current findings suggest a presumably higher vulnerability of the brain to early microcirculatory impairments after aSAH and highlight that timing of MTT elevations could be considered for the identification of patients at increased risk for poor neurological outcome due to DCI.

Abstract 105: Time for Collaterals? Evidence from 695 Endovascular Therapy Cases for Acute Stroke in ENDOSTROKE

Background: Recent stroke clinical trials demonstrate the profound impact of collaterals, yet time constraints are often cited as rationale for not evaluating or imaging collaterals prior to endovascular therapy (EVT). We examined the role of collaterals on patient outcomes in a large registry of EVT, analyzing actual time required to obtain such data before treatment of various occlusion sites and monitoring for potential harm.

Methods: ENDOSTROKE is an industry-independent, centrally-monitored multicenter registry evaluating EVT in routine clinical practice. Central reading of angiographic data blinded to clinical information was performed by the core lab in 695 patients assessing TICI scores, ASITN collateral grade and detailed procedural time metrics.

Results: 75% had anterior circulation strokes (including 270 proximal MCA, 106 ICAT, 90 cICA occlusions) and 25% posterior circulation strokes (including 148 basilar artery occlusions). Assessment of ASITN collateral grade was possible in 511 (73%) of patients; in 184 (27%) collateral status was not obtained prior to therapeutic intervention. Median time from initial angiography and first evidence of TICI 2A reperfusion was only one minute longer in patients with available ASITN scores than in those without (38 min (23, 61) vs. 37 (22, 55), p=0.552) and time-differences were even smaller in anterior circulation strokes (median time 37 min in both groups). In vertebrobasilar occlusion, this time metric was 5 minutes longer in those with available ASITN scores (39 min (24, 39)) than in those without (34 min (23, 52), p=0.357). Of those with ASITN available, patients with grade 3-4 had much better outcomes (48% 0-2 90-day mRS) than patients with grade 0-2 (30%, p<0.0001). No excess in complication rate (i.e. dissection, thrombemboli) was noted in the cohort with available ASITN.

Conclusions: Collaterals have a dramatic association with clinical outcomes in the largest endovascular study to date. In routine practice, EVT outcomes across various occlusion sites are strongly influenced by collateral grade. Negligible time of only a few minutes is typically required to obtain such essential data prior to treatment with no cost of incremental harm.

Stroke in patients with occlusion of the internal carotid artery: options for treatment

Ischemic stroke may occur in patients in whom vascular imaging shows the ipsilateral internal carotid artery (ICA) to be occluded. In younger patients this is often due to carotid artery dissection, while in older people this most likely results from cardiac embolism or thrombosis secondary to high-grade stenosis at the carotid bifurcation. Interventional techniques aim at recanalization of the carotid artery for early restoration of cerebral blood flow and secondary prevention of future strokes. In chronic ICA occlusion the ischemic infarct may be related to hemodynamic compromise. In this situation, extracranial-intracranial bypass surgery was introduced, but its role remains still unclear. Ischemic stroke may also occur in patients with a chronic occlusion of the contralateral ICA. This situation demands the usual stroke treatment, but surgical and neuroradiological interventions face a higher risk than unilateral vascular pathology. Medical treatment supports stroke prevention in carotid artery occlusion.

The extent of the perihemorrhagic perfusion zone correlates with hematoma volume in patients with lobar intracerebral hemorrhage

INTRODUCTION

Existing data on perfusion imaging assumes the perihemorrhagic zone (PHZ) in patients with intracerebral hemorrhage (ICH) to be size steady. This study investigates the size of the perihemorrhagic zone (PHZ) in patients with lobar ICH in relation to hematoma volume during the course of treatment using perfusion CT (PCT).

METHODS

The present analysis is based on a previously reported cohort of 20 patients undergoing surgical evacuation for lobar SICH, with pre- and early postoperative PCT scanning. Time to peak of the residue function (T max) was measured based on the 360° cortical banding method and singular value decomposition. The size of PHZ was determined before and after treatment and correlated with hematoma volume.

RESULTS

Preoperative mean hematoma volume constituted 63.0 ml (interquartile ranges (IQR) 39.7-99.4 ml), which correlated significantly (r=0.563, p=0.010) with mean PHZ size (5.67 cm, IQR 5.44-8.17 cm). Following a surgical hematoma evacuation, mean hematoma volume was reduced to 2.5 ml IQR 0.0-9.5 ml, which also resulted in a significant reduction of PHZ size to 0.45 cm(IQR 0.0-1.36 cm; p<0.001). There was no association between postoperative hematoma volume and size of the PHZ.

CONCLUSION

Our findings illustrate that the extent of the PHZ cannot be generally assumed to be constant in size and that this differs significantly following hematoma reduction in patients with space occupying lobar SICH.

Comparison of 18F-FET PET and perfusion-weighted MR imaging: a PET/MR imaging hybrid study in patients with brain tumors

PET using O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) provides important diagnostic information in addition to that from conventional MR imaging on tumor extent and activity of cerebral gliomas. Recent studies suggest that perfusion-weighted MR imaging (PWI), especially maps of regional cerebral blood volume (rCBV), may provide similar diagnostic information. In this study, we directly compared (18)F-FET PET and PWI in patients with brain tumors.

METHODS

Fifty-six patients with gliomas were investigated using static (18)F-FET PET and PWI. For comparison, 8 patients with meningiomas were included. We generated a set of tumor and reference volumes of interest (VOIs) based on morphologic MR imaging and transferred these VOIs to the corresponding (18)F-FET PET scans and PWI maps. From these VOIs, tumor-to-brain ratios (TBR) were calculated, and normalized histograms were generated for (18)F-FET PET and rCBV maps. Furthermore, in rCBV maps and in (18)F-FET PET scans, tumor volumes, their spatial congruence, and the distance between the local hot spots were assessed.

RESULTS

For patients with glioma, TBR was significantly higher in (18)F-FET PET than in rCBV maps (TBR, 2.28 ± 0.99 vs. 1.62 ± 1.13; P < 0.001). Histogram analysis of the VOIs revealed that (18)F-FET scans could clearly separate tumor from background. In contrast, deriving this information from rCBV maps was difficult. Tumor volumes were significantly larger in (18)F-FET PET than in rCBV maps (tumor volume, 24.3 ± 26.5 cm(3) vs. 8.9 ± 13.9 cm(3); P < 0.001). Accordingly, spatial overlap of both imaging parameters was poor (congruence, 11.0%), and mean distance between the local hot spots was 25.4 ± 16.1 mm. In meningioma patients, TBR was higher in rCBV maps than in (18)F-FET PET (TBR, 5.33 ± 2.63 vs. 2.37 ± 0.32; P < 0.001) whereas tumor volumes were comparable.

CONCLUSION

In patients with cerebral glioma, tumor imaging with (18)F-FET PET and rCBV yields different information. (18)F-FET PET shows considerably higher TBRs and larger tumor volumes than rCBV maps. The spatial congruence of both parameters is poor. The locations of the local hot spots differ considerably. Taken together, our data show that metabolically active tumor tissue of gliomas as depicted by amino acid PET is not reflected by rCBV as measured with PWI.

Peripheral neuropathy: assessment of proximal nerve integrity by diffusion tensor imaging

INTRODUCTION

We investigated the utility of diffusion tensor imaging (DTI) for detecting neuropathic changes in proximal nerve segments in patients with peripheral neuropathy.

METHODS

Twenty-one individuals with (n = 11) and without (n = 10) peripheral neuropathy underwent DTI of a defined sciatic nerve segment. Patients and controls were evaluated by clinical examination and nerve conduction studies at baseline and 6 months after the initial DTI scan.

RESULTS

The mean fractional anisotropy (FA) value was significantly lower in sciatic nerves from patients with peripheral neuropathy as compared with controls. Sciatic nerve FA values correlated with clinical disability scores and electrophysiological parameters of axonal damage at baseline and 6 months after MRI scan.

CONCLUSIONS

DTI-derived FA values are a sensitive measure to discriminate healthy from functionally impaired human sciatic nerve segments. DTI of proximal nerve segments may be useful for estimating the proximal axonal degeneration burden in patients with peripheral neuropathies.