Transient cortical blindness after diagnostic cerebral angiography - A single center report.

Background: Transient cortical blindness (TCB) has been reported as a complication after diagnostic cerebral angiography in 0.3-1% of cases. Our aim was to observe the frequency of TCB after diagnostic cerebral angiography over a period of 11 years using only hypo-osmolar, nonionic contrast agents and following a protocol to reduce both the total volume of injected contrast agent and the number of angiography series obtained. Methods: We retrospectively included all 2431 patients who received diagnostic cerebral angiographies at our institution. Primary outcome measure was the occurrence of TCB after diagnostic cerebral angiography, hypothesizing that the occurrence of TBC depends on the volume of contrast agent and angiography of the vertebrobasilary arteries. Results: Over the analyzed time period of 11 years, we did not observe a single case of TCB following diagnostic cerebral angiography. The median contrast volume used was 100 ml (IQR, 100-200), ranging from 15 ml to 500 ml. In our cohort, 61.5% of patients received a selective catheterization of the vertebrobasilary territory. In 99.8% of angiographies iopamidol was used a contrast agent. Conclusion: Our results indicate that following to certain aspects of the angiography protocol (using the hypoosmolar, non-ionic contrast agent iopamidol and reducing the number of catheterized vessels and angiography series to a diagnostic minimum) the frequency of transient cortical blindness as a complication of diagnostic cerebral angiography considerably can be very low.

Investigation of Cerebral Hemodynamics During Endovascular Aspiration: Development of an Experimental and Numerical Setup.

PURPOSE: Acute ischemic stroke is a life-threatening emergency caused by an occlusion of a cerebral artery through a blood clot. Aspiration thrombectomy is an endovascular therapy for the removal of vessel occlusions. However, open questions regarding the hemodynamics during the intervention remain, motivating investigations of blood flow within cerebral arteries. In this study, we present a combined experimental and numerical approach to analyze hemodynamics during endovascular aspiration. METHODS: We have developed an in vitro setup for investigations of hemodynamic changes during endovascular aspiration within a compliant model of patient-specific cerebral arteries. Pressures, flows, and locally resolved velocities were obtained. In addition, we established a computational fluid dynamics (CFD) model and compared the simulations during physiological conditions and in two aspiration scenarios with different occlusions. RESULTS: Flow redistribution within cerebral arteries after ischemic stroke is strongly dependent on the severity of the occlusion and on the volume flow extracted by endovascular aspiration. Numerical simulations exhibit an excellent correlation of R = 0.92 for flow rates and a good correlation of R = 0.73 for pressures. Further on, the local velocity field inside the basilar artery had a good agreement between CFD model and particle image velocimetry (PIV) data. CONCLUSION: The presented setup allows for in vitro investigations of artery occlusions and endovascular aspiration techniques on arbitrary patient-specific cerebrovascular anatomies. The in silico model provides consistent predictions of flows and pressures in several aspiration scenarios.

Results of Temporary Stent-assisted Coil Embolization (CATS) for the Treatment of Wide-neck Aneurysms : A 10-year Single Center Experience.

PURPOSE: In intracranial wide-neck aneurysms, simple coil embolization is often not a feasible treatment option. Balloon-assisted coiling comes with the drawback of blood flow impairment, whereas permanent stent placement requires long-term antiplatelet therapy. Temporary stent-assisted coiling (coiling assisted by temporary stenting, CATS) is an alternative that eliminates both disadvantages. Because prior studies included only small numbers of patients, it was our aim to analyze the safety and effectiveness of this technique in a larger cohort of patients. METHODS: We retrospectively evaluated all endovascular aneurysm treatments at our institution from 2011 to 2020. Out of a total of 688 aneurysm treatments, we intended to perform 95 (14%) with temporary stent-assisted coiling and included them in our study. RESULTS: Sixty-four (64)% of aneurysms were acutely ruptured, 3% were symptomatic but unruptured, and 33% were incidental. Successful stent recovery was possible in 93% of treatments. Initial complete and adequate occlusion rate were 53% and 82%, respectively. Long-term follow-up at 6 and 12 months was available for 71% and 44% of cases. Aneurysm recurrence was observed in 10% of cases after 6 months, and in 17% after 1 year or later. Periprocedural complications were noted in 12 cases (13%), of which only 1 complication was definitely associated with temporary stent-assisted coiling (1%). One of the periprocedural complications resulted in neurological damage, the other complications were asymptomatic. CONCLUSION: Temporary stent-assisted coiling appears to be a safe and effective treatment method in intracranial wide-neck aneurysms. Procedural safety appears to be comparable with balloon remodeling or permanent stent-assisted coiling, but it comes with the further benefit of diminished need for posttreatment antiplatelet therapy, which may improve the outcome of patients. However, to define the true value and potential benefit of this technique, further prospective studies are required.

Diagnostic Performance of Whole-Body Ultra-Low-Dose CT for Detection of Mechanical Ventriculoperitoneal Shunt Complications: A Retrospective Analysis.

BACKGROUND AND PURPOSE: Radiographic shunt series are still the imaging technique of choice for radiologic evaluation of VP-shunt complications. Radiographic shunt series are associated with high radiation exposure and have a low diagnostic performance. Our aim was to investigate the diagnostic performance of whole-body ultra-low-dose CT for detecting mechanical ventriculoperitoneal shunt complications. MATERIALS AND METHODS: This retrospective study included 186 patients (mean age, 54.8 years) who underwent whole-body ultra-low-dose CT (100 kV[peak]; reference, 10 mAs). Two radiologists reviewed the images for the presence of ventriculoperitoneal shunt complications, image quality, and diagnostic confidence. On a 5-point Likert scale, readers scored image quality and diagnostic confidence (1 = very low, 5 = very high). Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Radiation dose estimation of whole-body ultra-low-dose CT was calculated and compared with the radiation dose of a radiographic shunt series. RESULTS: 34 patients positive for VP-shunt complications were correctly identified on whole-body ultra-low-dose CT by both readers. No false-positive or -negative cases were recorded by any of the readers, yielding a sensitivity of 100% (95% CI, 87.3%-100%), a specificity of 100% (95% CI, 96.9%-100%), and perfect agreement (κ = 1). Positive and negative predictive values were high at 100%. Shunt-specific image quality and diagnostic confidence were very high (median score, 5; range, 5-5). Interobserver agreement was substantial for image quality (κ = 0.73) and diagnostic confidence (κ = 0.78). The mean radiation dose of whole-body ultra-low-dose CT was significantly lower than the radiation dose of a conventional radiographic shunt series (0.67 [SD, 0.4] mSv versus 1.57 [SD, 0.6] mSv; 95% CI, 0.79-1.0 mSv; P < .001). CONCLUSIONS: Whole-body ultra-low-dose CT allows detection of ventriculoperitoneal shunt complications with excellent diagnostic accuracy and diagnostic confidence. With concomitant radiation dose reduction on contemporary CT scanners, whole-body ultra-low-dose CT should be considered an alternative to the radiographic shunt series.

Causes of Death in Endovascularly Treated Patients with Acute Stroke.

BACKGROUND AND PURPOSE: Because stroke therapy has changed with the introduction of endovascular stroke treatment as a standard approach, studies on intrahospital causes of death from stroke are no longer up-to-date. The purpose of this observational study was to present the causes of death during hospitalization of patients with ischemic stroke who received endovascular stroke treatment, with the focus on a differentiation of curative and secondary palliative treatment. MATERIALS AND METHODS: We studied a total cohort of 1342 patients who received endovascular stroke treatment in a tertiary stroke center (Aachen, Germany) between 2010 and 2020 and analyzed the causes of death in all 326 consecutive deceased patients. We distinguished between curative treatment and a secondary palliative approach and analyzed causes of death and treatment numbers across the years. RESULTS: In the entire cohort of 326 deceased patients, the most common cause of death was of a cerebrovascular nature (51.5%), followed by pneumonia and sepsis (25.8%) and cardiovascular causes (8.3%). Neurovascular causes constituted 75.8% of reasons for palliation. In the group with a secondary palliative approach, causes of death were neurovascular in 54.0% of patients and pneumonia and sepsis in 26.0% of patients. CONCLUSIONS: Cerebrovascular causes in patients with stroke play a major role in the intrahospital causes of death and reasons for palliation. Considering the large proportion of secondarily palliative-treated patients, reasons for palliation should be considered instead of causes of death to avoid concealment by, for example, life-terminating measures.

Treatment strategy and long-term outcome in patients with deep lumbosacral arteriovenous fistulas. A single center analysis in nineteen patients.

OBJECTIVE: Deep lumbosacral dural arteriovenous fistulas (lsDAVF) are rare and present serious diagnostic and treatment difficulties. In our current analysis we present our treatment strategy and the long-term clinical outcome of nineteen patients with lsDAVF. PATIENTS AND METHODS: We retrospectively analyzed our radiological and medical records for patients presenting with SDAVF between 1990 and 2018 at the University Hospital Aachen. We identified twenty patients with a lsDAVF. All patients were treated surgically. One patient died of pulmonary embolism three months after treatment and was excluded from our outcome analysis. Clinical data at time of admission, discharge, one year after discharge and at the last follow-up were evaluated according to modified Aminoff-Logue disability score (AL-score) for this analysis. RESULTS: Mean age was 65 ±â€¯7 years (median, 67; range, 53-78), sixteen patients (84 %) were male. After surgery, four patients developed a recurrent fistula in the same shunt zone and were re-treated microsurgically. Follow-up data one year after treatment was available in 15 patients. No relevant changes in AL-score were observed within this period. For the long-term follow-up analysis, data of 13 patients were available; 38.5 % of patients developed late functional deterioration. CONCLUSION: In our cohort, patients with deep lumbosacral dural arteriovenous fistula had a higher risk of early recurrence compared to patients with thoracolumbar SDAVF, with a considerable percentage of late functional deterioration. Thus strict clinical and radiologic long-term follow-up examinations are recommended in those patients.

Increased Water Content in Periventricular Caps in Patients without Acute Hydrocephalus.

BACKGROUND AND PURPOSE: Periventricular caps are a common finding on MR imaging and are believed to reflect focally increased interstitial water content due to dysfunctional transependymal transportation rather than ischemic-gliotic changes. We compared the quantitative water content of periventricular caps and microvascular white matter lesions, hypothesizing that periventricular caps associated with increased interstitial fluid content display higher water content than white matter lesions and are therefore differentiable from microvascular white matter lesions by measurement of the water content. MATERIALS AND METHODS: In a prospective study, we compared the water content of periventricular caps and white matter lesions in 50 patients using a quantitative multiple-echo, gradient-echo MR imaging water-mapping sequence. RESULTS: The water content of periventricular caps was significantly higher than that of white matter lesions (P = .002). Compared with normal white matter, the mean water content of periventricular caps was 17% ± 5% higher and the mean water content of white matter lesions was 11% ± 4% higher. Receiver operating characteristic analysis revealed that areas in which water content was 15% higher compared with normal white matter correspond to periventricular caps rather than white matter lesions, with a specificity of 93% and a sensitivity of 60% (P < .001). There was no significant correlation between the water content of periventricular caps and whole-brain volume (P = .275), white matter volume (P = .243), gray matter volume (P = .548), lateral ventricle volume (P = .800), white matter lesion volume (P = .081), periventricular cap volume (P = .081), and age (P = .224). CONCLUSIONS: Quantitative MR imaging allows differentiation between periventricular caps and white matter lesions. Water content quantification of T2-hyperintense lesions may be a useful additional tool for the characterization and differentiation of T2-hyperintense diseases.

Endovascular stroke treatment does not preclude high thrombolysis rates.

BACKGROUND AND PURPOSE: In 1995 intravenous recombinant tissue plasminogen activator (IVRTPA) was the first reperfusion therapy to be approved in patients with acute ischaemic stroke (AIS). The significance and impact of IVRTPA in times of modern endovascular stroke treatment (EST) were analysed in a German academic stroke centre. METHODS: A retrospective observational cohort analysis of 1034 patients with suspected AIS presenting at the emergency department in 2014 was performed. Patients were evaluated for baseline characteristics, reperfusion procedures, IVRTPA eligibility, clinical outcome, symptomatic intracranial haemorrhage (sICH) and mortality. Data acquisition was part of an investigator-initiated, prospective and blinded end-point registry. RESULTS: In 718 (69%) patients the diagnosis of symptomatic AIS was confirmed. 419 (58%) patients presented within 4.5 h of symptom onset and of those 260 (62%) received reperfusion therapy (IVRTPA alone, n = 183; combination or bridging therapy, n = 60; EST alone, n = 17). Subtracting cases with absolute contraindications for IVRTPA resulted in an effective thrombolysis rate of 82%. sICH occurred in two patients treated with IVRTPA alone (1.1%). The median door-to-needle interval was 30 min. Fifty (17%) non-EST eligible AIS patients presenting within 4.5 h without absolute contraindications did not receive IVRTPA mainly due to mild or regressive symptoms. Most of these untreated IVRTPA eligible patients (82%) were discharged with a good clinical outcome (modified Rankin Scale ≤ 2). CONCLUSIONS: Intravenous recombinant tissue plasminogen activator remains the most frequently applied reperfusion therapy in AIS patients presenting within 4.5 h of onset in a tertiary stroke centre. An effective thrombolysis rate of over 80% can be achieved without increased rates of sICH.

Balloon-Guide Catheters Are Needed for Effective Flow Reversal during Mechanical Thrombectomy.

BACKGROUND AND PURPOSE: Blood flow management in the carotid artery during mechanical thrombectomy is crucial for safety and effectiveness. There is an ongoing discussion about whether balloon-guide catheters or large-bore sheaths are needed for effective flow management. We compared general flow characteristics of proximal aspiration through a large-bore sheath and a balloon-guide catheter in a porcine in vivo model. MATERIALS AND METHODS: We investigated blood flow in a porcine common carotid artery with and without aspiration (VacLok syringe and Penumbra pump, Pump MAX) through an 8F-long sheath and an 8F balloon-guide catheter. Blood hemodynamics were assessed via continuous duplex sonography. RESULTS: Average vessel diameter and baseline blood flow were 4.4 ± 0.2 mm and 244 ± 20 mL/min, respectively. For the 8F sheath, pump aspiration resulted in a significant flow reduction (225 ± 25 mL/min, P < .001), but with a persisting antegrade stream. Manual aspiration resulted in collapse of the vessel in 2 of 7 measurements and oscillatory flow with antegrade systolic and retrograde diastolic components in the remaining 5 measurements. Net flow was antegrade (52 ± 44 mL/min) in 3 and retrograde (-95 ± 52 mL/min) in the remaining 2 measurements. For balloon-guide catheters, balloon inflation always resulted in flow arrest. Additional pump or manual aspiration resulted in significant flow reversal of -1100 ± 230 and -468 ± 46 mL/min, respectively (both, P < .001). CONCLUSIONS: Only balloon-guide catheters allow reliable blood flow arrest and flow reversal in combination with aspiration via syringes or high-flow pump systems. Aspiration through an 8F sheath results in either collapse of the vessel or oscillatory flow, which can result in a net antegrade or retrograde stream.

Under Pressure: Comparison of Aspiration Techniques for Endovascular Mechanical Thrombectomy.

BACKGROUND AND PURPOSE: Blood flow should be interrupted during mechanical thrombectomy to prevent embolization of clot fragments. The purpose of our study was to provide a handy overview of the most common aspiration devices and to quantify their flow characteristics. MATERIALS AND METHODS: We assessed volumetric flow rates generated by a 60-mL VacLok vacuum pressure syringe, a Pump MAX aspiration pump, and a Dominant Flex suction pump connected to the following: 1) an 8F long sheath, 2) an 8F balloon-guide catheter, 3) an ACE 64 distal aspiration catheter, and 4) an AXS Catalyst 6 Distal Access Catheter. We used a water/glycerol solution, which was kept at a constant temperature of 20°C (viscosity, 3.7 mPa · s). RESULTS: Aspiration with the syringe and the Dominant Flex suction pump achieved the highest flows, whereas aspiration with the Pump MAX was significantly lower (P < .001). Resistors in the aspiration system (tubing, connectors, and so forth) restricted flows, especially when the resistance of the catheter was small (due to its large diameter) and the connected resistors became the predominant resistance (P < .001). The syringe achieved an average vacuum pressure of -90 kPa, and the resulting flow was constant during almost the entire procedure of filling the syringe. CONCLUSIONS: Sixty-milliliter VacLok vacuum pressure syringes and the Dominant Flex suction pump achieved high and constant flows likely sufficient to reverse blood flow during thrombectomy with an 8F sheath or balloon-guide catheter in the ICA and modern distal aspiration catheters in the MCA. The Pump MAX aspiration pump is dedicated for use with distal aspiration catheters and is unlikely to reverse blood flow in the ICA and MCA without balloon protection.

Implant-specific follow-up imaging of treated intracranial aneurysms: TOF-MRA vs. metal artifact reduced intravenous flat panel computed tomography angiography (FPCTA).

AIM: To compare the diagnostic quality of time-of-flight magnetic resonance angiography (TOF-MRA) and metal-artefact-reduction (MAR) flat-panel-detector computed tomography angiography (FPCTA) and to determine the imaging technique best suited for evaluation endovascular and surgically treated aneurysms. METHODS: The image quality of TOF-MRA and MAR-FPCTA of 44 intracranial implants (coiling: n=20; clipping: n=15; coiling + stenting: n=9) in a patient cohort of 25 was evaluated by two independent readers. Images obtained using MAR-FPCTA (20 second scan time, 496 projections, intravenous contrast medium administration; Artis Zee, Siemens Healthcare, Forchheim) were compared with TOF-MRA-images (1.5 or 3 T). Nominal data were analysed using McNemar's chi-square test and ordinal variables using the Wilcoxon rank test. RESULTS: Compared to TOF-MRA, MAR-FPCTA was significantly better suited to detect aneurysm remnants and to evaluate parent vessels after clipping (p<0.01). For coil packages >160 mm3, TOF-MRA provided significantly better assessment than MAR-FPCTA (p<0.01). For small coil packages (<160 mm3), no significant difference between TOF-MRA and MAR-FPCTA (p=0.232) was observed. For different clip sizes (cut-off 492 mm3) likewise no significant differences were found. The interobserver comparison showed high interrater agreement. CONCLUSION: MAR-FPCTA is significantly better suited for follow-up examinations of clipped aneurysms, whereas for larger coil packages TOF-MRA is preferable. Smaller coil packages can be analysed using MAR-FPCTA or TOF-MRA.

Clinical and Radiologic Characteristics of Deep Lumbosacral Dural Arteriovenous Fistulas.

BACKGROUND AND PURPOSE: Spinal dural arteriovenous fistulas located in the deep lumbosacral region are rare and the most difficult to diagnose among spinal dural arteriovenous fistulas located elsewhere in the spinal dura. Specific clinical and radiologic features of these fistulas are still inadequately reported and are the subject of this study. MATERIALS AND METHODS: We retrospectively evaluated all data of patients with spinal dural arteriovenous fistulas treated and/or diagnosed in our institution between 1990 and 2017. Twenty patients with deep lumbosacral spinal dural arteriovenous fistulas were included in this study. RESULTS: The most common neurologic findings at the time of admission were paraparesis (85%), sphincter dysfunction (70%), and sensory disturbances (20%). Medullary T2 hyperintensity and contrast enhancement were present in most cases. The filum vein and/or lumbar veins were dilated in 19/20 (95%) patients. Time-resolved contrast-enhanced dynamic MRA indicated a spinal dural arteriovenous fistula at or below the L5 vertebral level in 7/8 (88%) patients who received time-resolved contrast-enhanced dynamic MRA before DSA. A bilateral arterial supply of the fistula was detected via DSA in 5 (25%) patients. CONCLUSIONS: Clinical symptoms caused by deep lumbosacral spinal dural arteriovenous fistulas are comparable with those of spinal dural arteriovenous fistulas at other locations. Medullary congestion in association with an enlargement of the filum vein or other lumbar radicular veins is a characteristic finding in these patients. Spinal time-resolved contrast-enhanced dynamic MRA facilitates the detection of the drainage vein and helps to localize deep lumbosacral-located fistulas with a high sensitivity before DSA. Definite detection of these fistulas remains challenging and requires sufficient visualization of the fistula-supplying arteries and draining veins by conventional spinal angiography.

Necessary Catheter Diameters for Mechanical Thrombectomy with ADAPT.

BACKGROUND AND PURPOSE: Large-bore catheters allow mechanical thrombectomy in ischemic stroke by engaging and retrieving clots without additional devices (direct aspiration first-pass technique [ADAPT]). The purpose of this study was to establish a model for minimal catheter diameters needed for ADAPT. MATERIALS AND METHODS: We established a theoretic model for the calculation of minimal catheter diameters needed for ADAPT. We then verified its validity in 28 ADAPT maneuvers in a porcine in vivo model. To account for different mechanical thrombectomy techniques, we factored in ADAPT with/without a hypothetic 0.021-inch microcatheter or 0.014-inch microwire inside the lumen of the aspiration catheter and aspiration with a 60-mL syringe versus an aspiration pump. RESULTS: According to our calculations, catheters with an inner diameter of >0.040 inch and >0.064 inch, respectively, are needed to be effective in the middle cerebral artery (2.5-mm diameter) or in the internal carotid artery (4 mm) in an average patient. There was a significant correlation between predicted and actual thrombectomy results (P = .010). Our theoretic model had a positive and negative predictive value of 78% and 79%, respectively. Sensitivity and specificity were 88% and 64%, respectively. CONCLUSIONS: Our theoretic model allows estimating the minimal catheter diameters needed for successful mechanical thrombectomy with ADAPT, as demonstrated by the good agreement with our animal experiments. Our model will be helpful to interventionalists in avoiding selecting catheters that are likely too small to be effective.

Influence of carotid tortuosity on internal carotid artery access time in the treatment of acute ischemic stroke.

Purpose Carotid artery anatomy is thought to influence internal carotid artery access time (ICA-AT) in patients requiring mechanical thrombectomy for acute ischemic stroke. This study investigates the association between ICA-AT and carotid anatomy. Material and methods Computed tomography angiography (CTA) data of 76 consecutive patients presenting with acute ischemic stroke requiring mechanical thrombectomy for middle cerebral artery or carotid T occlusion were evaluated. The supraaortic extracranial vasculature was analyzed regarding take-off angles and curvature of the affected side. Digital subtraction angiography data were primarily analyzed regarding ICA-AT and secondarily regarding recanalization time and radiographic result. Results ICA-AT was significantly influenced by vessel tortuosity. Take-off angle of the left common carotid artery ( p = 0.001) and the brachiocephalic trunk ( p = 0.002) as well as the tortuosity of the common carotid artery ( p = 0.002) had highest impact on ICA-AT. For recanalization time, however, we found only the take-off angle of the left common carotid artery to be of significance ( p = 0.020). There was a tendency for ICA-AT to correlate with successful (mTICI ≥ 2 b) revascularization (average time of successful results was 24.3 minutes, of unsuccessful was 35.6 minutes; p = 0.065). Every evaluated segment with less carotid tortuosity showed a carotid AT below 25 minutes. Conclusion Supraaortic vessel tortuosity significantly influences ICA-AT in mechanical thrombectomy for an acute large vessel. There furthermore was a trend for lower successful recanalization rates with increasing ICA-AT.

Temporary Stent-Assisted Coil Embolization as a Treatment Option for Wide-Neck Aneurysms.

BACKGROUND AND PURPOSE: Simple coil embolization is often not a feasible treatment option in wide-neck aneurysms. Stent-assisted coil embolization helps stabilize the coils within the aneurysm. Permanent placement of a stent in an intracranial vessel, however, requires long-term platelet inhibition. Temporary stent-assisted coiling is an alternative technique for the treatment of wide-neck aneurysms. To date, only case reports and small case series have been published. Our purpose was to retrospectively analyze the effectiveness and safety of temporary stent-assisted coiling in a larger cohort. MATERIALS AND METHODS: Research was performed for all patients who had undergone endovascular aneurysm treatment in our institution (University Hospital Aachen) between January 2010 and December 2015. During this period, 355 consecutive patients had undergone endovascular aneurysm treatment. We intended to treat 33 (9.2%) of them with temporary stent-assisted coiling, and they were included in this study. Incidental and acutely ruptured aneurysms were included. RESULTS: Sufficient occlusion was achieved in 97.1% of the cases. In 94%, the stent could be fully recovered. Complications occurred in 5 patients (14.7%), whereas in only 1 case was the complication seen as specific to stent-assisted coiling. CONCLUSIONS: Temporary stent-assisted coiling is an effective technique for the treatment of wide-neck aneurysms. Safety is comparable with that of stent-assisted coiling and coiling with balloon remodeling.

Low-Dose Volume-Perfusion CT of the Brain: Effects of Radiation Dose Reduction on Performance of Perfusion CT Algorithms.

PURPOSE: We aimed to compare different computed tomography (CT) perfusion post-processing algorithms regarding image quality of perfusion maps from low-dose volume perfusion CT (VPCT) and their diagnostic performance regarding the detection of ischemic brain lesions. METHODS AND MATERIALS: We included VPCT data of 21 patients with acute stroke (onset < 6h), which were acquired at 80 kV and 180 mAs. Low-dose VPCT datasets with 72 mAs (40 % of original dose) were generated using realistic low-dose simulation. Perfusion maps (cerebral blood volume (CBV); cerebral blood flow (CBF) from original and low-dose datasets were generated using two different commercially available post-processing methods: deconvolution-based method (DC) and maximum slope algorithm (MS). The resulting DC and MS perfusion maps were compared regarding perfusion values, signal-to-noise ratio (SNR) as well as image quality and diagnostic accuracy as rated by two blinded neuroradiologists. RESULTS: Quantitative perfusion parameters highly correlated for both algorithms and both dose levels (r ≥ 0.613, p < 0.001). Regarding SNR levels and image quality of the CBV maps, no significant differences between DC and MS were found (p ≥ 0.683). Low-dose MS CBF maps yielded significantly higher SNR levels (p < 0.001) and quality scores (p = 0.014) than those of DC. Low-dose CBF and CBV maps from both DC and MS yielded high sensitivity and specificity for the detection of ischemic lesions (sensitivity ≥ 0.82, specificity ≥ 0.90). CONCLUSION: Our results indicate that both methods produce diagnostically sufficient perfusion maps from simulated low-dose VPCT. However, MS produced CBF maps with significantly higher image quality and SNR than DC, indicating that MS might be more suitable for low-dose VPCT imaging.

MRI Appearance of Intracerebral Iodinated Contrast Agents: Is It Possible to Distinguish Extravasated Contrast Agent from Hemorrhage?

BACKGROUND AND PURPOSE: Hyperattenuated cerebral areas on postinterventional CT are a common finding after endovascular stroke treatment. There is uncertainty about the extent to which these hyperattenuated areas correspond to hemorrhage or contrast agent that extravasated into infarcted parenchyma during angiography. We evaluated whether it is possible to distinguish contrast extravasation from blood on MR imaging. MATERIALS AND METHODS: We examined the influence of iodinated contrast agents on T1, T2, and T2* and magnetic susceptibility in a phantom model and an ex vivo animal model. We determined T1, T2, and T2* relaxation times and magnetic susceptibility of iopamidol and iopromide in dilutions of 1:1; 1:2; 1:4; 1:10; and 1:100 with physiologic saline solution. We then examined the appearance of intracerebral iopamidol on MR imaging in an ex vivo animal model. To this end, we injected iopamidol into the brain of a deceased swine. RESULTS: Iopamidol and iopromide cause a negative susceptibility shift and T1, T2, and T2* shortening. The effects, however, become very small in dilutions of 1:10 and higher. Undiluted iopamidol, injected directly into the brain parenchyma, did not cause visually distinctive signal changes on T1-weighted spin-echo, T2-weighted turbo spin-echo, and T2*-weighted gradient recalled-echo imaging. CONCLUSIONS: It is unlikely that iodinated contrast agents extravasated into infarcted brain parenchyma cause signal changes that mimic hemorrhage on T1WI, T2WI, and T2*WI. Our results imply that extravasated contrast agents can be distinguished from hemorrhage on MR imaging.

Neurothrombectomy in acute ischaemic stroke: a prospective single-centre study and comparison with randomized controlled trials.

BACKGROUND AND PURPOSE: In the last few months five multicentre, randomized controlled trials (RCTs) unequivocally showed the superiority of mechanical thrombectomy in large vessel occlusion acute ischaemic stroke compared to systemic thrombolysis. Despite varying inclusion criteria and time intervals from onset to revascularization overall increases of good functional outcome between 55% and 81% were reported. However, only a minority of screened patients (approximately 1%) were eligible for intra-arterial (IA) therapy. METHODS: An investigator-initiated, single-centre, prospective and blinded end-point analysis was performed of 3123 consecutive patients with acute ischaemic stroke presenting between February 2010 and December 2014. RESULTS: One hundred and fifty-four patients [4.9%, age (years) mean (SD), median (interquartile range) 71.2 (±14), 74.7 (65.9-81.4)] met the inclusion criteria of sparse early ischaemic signs on initial standard cranial computed tomography (CT) (ASPECT score ≥7), large vessel occlusion in the anterior circulation on CT angiography and start of treatment within 6 h of onset of symptoms. After consensual interdisciplinary treatment decisions 130 patients (4.2%) received IA treatment - in the majority stent-assisted thrombectomy in combination with intravenous (IV) recombinant tissue plasminogen activator - and 24 patients (0.7%) standard IV thrombolysis. On 3 months' follow-up an overall significant improvement of disability (P = 0.05) as measured by the modified Rankin Scale was shown in favour of the IA treatment group. Good functional outcome was achieved in about twice as many patients (IA vs. IV, 41.2% vs. 21.2%; P = 0.078). CONCLUSION: By choosing pragmatic inclusion criteria state-of-the-art IA therapy of a specialized tertiary stroke centre can be safely applied under real-world conditions to a higher percentage of patients with similar success to the recently published RCTs.

Clinical Impact of Ventilation Duration in Patients with Stroke Undergoing Interventional Treatment under General Anesthesia: The Shorter the Better?

BACKGROUND AND PURPOSE: Whether general anesthesia for neurothrombectomy in patients with ischemic stroke has a negative impact on clinical outcome is currently under discussion. We investigated the impact of early extubation and ventilation duration in a cohort that underwent thrombectomy under general anesthesia. MATERIALS AND METHODS: We analyzed 103 consecutive patients from a prospective stroke registry. They met the following criteria: CTA-proved large-vessel occlusion in the anterior circulation, ASPECTS above 6 on presenting cranial CT, revascularization by thrombectomy with the patient under general anesthesia within 6 hours after onset of symptoms, and available functional outcome (mRS) 90 days after onset. RESULTS: The mean ventilation time was 128.07 ± 265.51 hours (median, 18.5 hours; range, 1-1244.7 hours). Prolonged ventilation was associated with pneumonia during hospitalization and unfavorable functional outcome (mRS ≥3) and death at follow-up (Mann-Whitney U test; P ≤ .001). According to receiver operating characteristic analysis, a cutoff after 24 hours predicted unfavorable functional outcome with a sensitivity and specificity of 60% and 78%, respectively. Our results imply that delayed extubation was not associated with a less favorable clinical outcome compared with immediate extubation after the procedure. CONCLUSIONS: Short ventilation times are associated with a lower pneumonia rate and more favorable clinical outcome. Cautious interpretation of our data implies that whether patients are extubated immediately after the procedure is irrelevant for clinical outcome as long as ventilation does not exceed 24 hours.

Stent Retriever Thrombectomy in Patients Who Are Ineligible for Intravenous Thrombolysis: A Multicenter Retrospective Observational Study.

BACKGROUND AND PURPOSE: Intravenous thrombolysis with rtPA is the standard of care for patients with acute ischemic stroke within 4.5 hours after symptom onset. However, a considerable number of patients are ineligible for IV thrombolysis due to various contraindications. Recent studies have proved the superiority of mechanical thrombectomy for patients with large-vessel occlusions in combination with IV rtPA compared with IV rtPA alone. We aimed to demonstrate the efficacy of mechanical thrombectomy for patients who are ineligible for IV rtPA. MATERIALS AND METHODS: Patients from the stroke registries of 4 dedicated centers who were treated with mechanical thrombectomy from January 2010 to October 2014 were retrospectively evaluated. Inclusion criteria were the following: acute stroke due to proved large-artery occlusion, ineligibility for IV thrombolysis, and a timeframe of ≤4.5 hours between stroke and the start of mechanical thrombectomy. Recanalization success, periprocedural complications, clinical outcome, and hemorrhages were evaluated. RESULTS: One hundred thirty endovascular recanalization procedures were identified. The locations were the following: proximal ICA in 17 (13.1%), terminus ICA in 25 (19.2%), M1 segment in 77 (59.2%), and M2 segment in 11 (8.5%). TICI 2b/3 results were achieved in 101 (77.7%), and an mRS score of 0-2 in 47 patients (37.9%). There was a significant correlation between TICI 2b/3 results and good clinical outcomes (87.2% versus 6.8%; P = .048). A good clinical result was most frequent when recanalization was achieved within 4.5 hours (37/74 = 50% versus 10/50 = 20.0%; P = .001). Symptomatic hemorrhage occurred in 13.1% of patients; mortality was 24.2%. Periprocedural complications were recorded in 10 patients (7.7%). CONCLUSIONS: Mechanical thrombectomy can achieve good clinical outcomes in patients with acute large-artery occlusion ineligible for IV thrombolysis, in particular when recanalization is reached early.