Christian A. Taschner

Intracranial Arteriovenous Malformation : Time-resolved Contrast-enhanced MR Angiography with Combination of Parallel Imaging, Keyhole Acquisition, and k-Space Sampling Techniques at 1,5 T

PURPOSE To prospectively compare the agreement between digital subtraction angiography (DSA) and time-resolved magnetic resonance (MR) angiography with sensitivity encoding (SENSE) in combination with keyhole acquisition and contrast material-enhanced robust-timing angiography (CENTRA) k-space sampling techniques for the characterization of intracranial arteriovenous malformations (AVMs). MATERIALS AND METHODS The institutional review board approved the study; informed consent was obtained from all patients (or their parents). Twenty-eight patients (15 male, 13 female; mean age, 38.6 years; age range, 16-61 years) with 29 previously diagnosed, untreated intracranial AVMs who were referred for stereotactic gamma knife radiosurgery were evaluated. Preinterventional imaging included intraarterial DSA and time-resolved MR angiography. The time-resolved MR angiography sequence included SENSE with a 1.5-T imager and was optimized by applying keyhole acquisition and CENTRA techniques. Time-resolved MR angiograms were reviewed by two independent raters and compared with DSA images with regard to arterial feeders, nidus size, and venous drainage. kappa Statistics were applied to determine interobserver and intermodality agreement. RESULTS MR angiography enabled time-resolved (1.7 seconds per volume) visualization of cerebral vessels from axis to vertex at high spatial resolution (true voxel size, 1 x 1 x 2 mm). All 25 nidi detected at intraarterial DSA were visualized at time-resolved MR angiography. Intermodality agreement was excellent for arterial feeders (kappa = 0.91; 95% confidence interval [CI]: 0.786, 1.000) and venous drainage (kappa = 0.94; 95% CI: 0.814, 1.000) and was good for nidus size (kappa = 0.76; 95% CI: 0.562, 0.950). CONCLUSION The agreement (good to excellent) between time-resolved MR angiographic and DSA findings suggests that time-resolved MR angiography is a reliable tool for the characterization of intracranial AVMs with respect to arterial feeders, nidus size, and venous drainage.

Endovascular treatment of complex aneurysms at the vertebrobasilar junction with flow-diverting stents: initial experience.

BACKGROUND Large or giant complex vertebrobasilar junction aneurysms have a dismal natural history and are often challenging to treat with standard endovascular or neurosurgical techniques. OBJECTIVE To report initial experience with endovascular treatment of these aneurysms using flow-diverting stents (FDS). METHODS Ten patients with FDS treatment of complex vertebrobasilar junction aneurysms were collected from 4 large cerebrovascular centers. Clinical/angiographic presentation and outcome were retrospectively analyzed. RESULTS Of 10 aneurysms, 7 presented with brainstem compression, 2 with ischemia, and 1 with subarachnoid hemorrhage, and 3 were recurrent after stent-assisted treatments. Eight were giant. Morphology was fusiform in 5, fusiform dissecting in 1, and multilobulated saccular in 4. Six were partially thrombosed. In addition to FDS (mean number of devices, 3.9; range, 1-9), contralateral vertebral artery sacrifice and adjunctive coiling were performed in 9 and 5 of the 10 patients, respectively. At follow-up, 5 of 10 were completely occluded, 4 showed minimal residual filling, and 1 was retreated with an additional FDS. Postinterventionally, worsening mass effect and ischemic complications were seen in 2 and 4 of 10, respectively. Clinical outcome was good in 6 (modified Rankin Scale score, 0-2). Four fatalities were related to sequelae of subarachnoid hemorrhage, late FDS thrombosis, progressive mass effect, and delayed intracranial hemorrhage. CONCLUSION FDS may be used to treat complex vertebrobasilar junction aneurysms with overall good angiographic outcome. A combined reconstructive/deconstructive approach appears useful to avoid endoleaks. FDS strategies, like other endovascular and neurosurgical approaches to these lesions, are associated with significant risk and therefore should be reserved for those cases in which alternative approaches either are deemed unsafe or are likely to be ineffective. ABBREVIATIONS FDS, flow-diverting stentPED, Pipeline Embolization DeviceSAH, subarachnoid hemorrhageVA, vertebral arteryVBJ, vertebrobasilar junction.

Mechanical thrombectomy with the Penumbra recanalization device in acute ischemic stroke

BACKGROUND AND PURPOSE The aim of this study was to assess the clinical outcome of patients treated with the Penumbra system (PS) for acute ischemic stroke. A retrospective, monocentric matched-pair analysis in comparison with patients treated by intraarterial thrombolysis (IAT) with alteplase was designed for this purpose. METHODS Twenty-two consecutive patients, (mean age 62), with acute ischemic stroke and National Institutes of Health Stroke Scale (NIHSS) scores ≥ 7 were treated with the PS. Twenty corresponding patients could be identified, treated with IAT. Matches were sought for initial NIHSS score and target vessels. Thrombolysis in myocardial infarction (TIMI) grades, mortality rates, NIHSS upon discharge, and modified Rankin scores (mRs) at 90 days were compared. RESULTS A total of 32 vessels in 20 patients were treated in either arm of the study. Recanalization to TIMI 2/3 was successful in 25/32 (78%) of target vessels with the PS, and 17/32 (53%) of target vessels in the IAT group. Upon discharge, 2/20 patients treated with PS and 7/20 patients treated with IAT had a NIHSS score of 0 to 1 or an improvement greater or equal to 10-point on the NIHSS scale. All cause mortality at 90 days was 3/20 patients treated with PS, and 2/20 patients treated with IAT. Three out of twenty patients treated with PS and 7/20 patients treated with IAT had a mRS of ≤ 2 at 90 days. CONCLUSION The Penumbra system is effective in re-opening occluded major arteries. Our data seems to indicate that not all patients benefit clinically from improved revascularization of occluded major arteries.

Neurosurgical treatment for aneurysm remnants or recurrences after coil occlusion: Commentary

OBJECTIVENeurosurgical management of residual aneurysms (RA) after coiling remains a challenging issue. We present a consecutive series of 21 patients who underwent microsurgical treatment of a previously coiled aneurysm. METHODSWe retrospectively reviewed a consecutive series of 21 patients who underwent operations for an RA after coiling between 1997 and 2007. Postcoiling follow-up imaging included brain magnetic resonance angiography and digital subtraction angiography. The decision for surgical treatment was made when an RA was significant and unsuitable for re-embolization. Data related to the RA and to the surgical technique were analyzed. Postoperative outcome was evaluated with the Glasgow Outcome Scale. RESULTSTwenty aneurysms were initially ruptured. Twelve had undergone complete coil occlusion, whereas 6 had a residual neck, 2 had a residual lobule, and 1 had a residual sac. The aneurysms were in the anterior circulation in 18 cases and in the posterior circulation in 3 cases. Twenty RAs were excluded with the apposition of 1 clip beneath the coils, 2 required a temporary occlusion, 2 required extraction of the coils, and 1 presented with an operative rupture. All aneurysms, except 2 that had their residual neck wrapped, were completely occluded. The postoperative Glasgow Outcome Scale score was unchanged in 90% of patients, and 2 patients sustained a moderate disability. CONCLUSIONMicrosurgical treatment of RA after endovascular treatment is effective, provided that patients are selected appropriately. The surgical treatment of recanalized aneurysms after coiling is challenging but can result in a good outcome with low morbidity and no mortality.

Immunohistochemical Analysis of Thrombi Retrieved During Treatment of Acute Ischemic Stroke: Does Stent-Retriever Cause Intimal Damage?

Background and Purpose— To provide evidence whether mechanical thrombectomy with stent-retrievers in the treatment of acute ischemic stroke causes intimal damage. Methods— This study analyzed thrombi retrieved by mechanical thrombectomy from cerebral arteries in 48 consecutive patients with acute ischemic stroke for the presence of endothelial cells using CD34 antibodies. Results— Of 48 thrombi analyzed, CD34-positive cells were absent in 20, present as isolated cells in 21, and found in clusters in 7 thrombi. We did not find any subendothelial vessel wall structures. Conclusions— Our findings suggest that mechanical thrombectomy with stent-retrievers does not cause relevant intimal damage in acute ischemic stroke treatment. Clinical Trial Registration— URL: http://www.germanctr.de. Unique identifier: DRKS00004695

Early identification of individuals at high risk for cerebral infarction after aneurysmal subarachnoid hemorrhage: the BEHAVIOR score

Cerebral infarction (CI) is a crucial complication of aneurysmal subarachnoid hemorrhage (SAH) associated with poor clinical outcome. We aimed at developing an early risk score for CI based on clinical characteristics available at the onset of SAH. Out of a database containing 632 consecutive patients with SAH admitted to our institution from January 2005 to December 2012, computed tomography (CT) scans up to day 42 after ictus were evaluated for CIs. Different parameters from admission up to aneurysm treatment were collected with subsequent construction of a risk score. Seven clinical characteristics were independently associated with CI and included in the Risk score (BEHAVIOR Score, 0 to 11 points): Blood on CT scan according to Fisher grade ≥ 3 (1 point), Elderly patients (age ≥ 55 years, 1 point), Hunt&Hess grade ≥ 4 (1 point), Acute hydrocephalus requiring external liquor drainage (1 point), Vasospasm on initial angiogram (3 points), Intracranial pressure elevation > 20 mm Hg (3 points), and treatment of multiple aneurysms (‘Overtreatment’, 1 point). The BEHAVIOR score showed high diagnostic accuracy with respect to the absolute risk for CI (area under curve = 0.806, P < 0.0001) and prediction of poor clinical outcome at discharge (P < 0.0001) and after 6 months (P = 0.0002). Further validation in other SAH cohorts is recommended.

Predictors of Severity of Cerebral Vasospasm caused by Aneurysmal Subarachnoid Hemorrhage

BACKGROUND Cerebral vasospasm is one of the leading causes of poor outcome after aneurysmal subarachnoid hemorrhage. The risk factors for the development of vasospasm have been evaluated in many clinical studies. However, it remains unclear if vasospasm severity can be predicted. The purpose of this study was to determine if different demographic and clinical factors that appear to be predictors of vasospasm can also prognosticate the severity of cerebral vasospasm. METHODS We retrospectively analyzed consecutive patients with subarachnoid hemorrhage who underwent endovascular vasospasm treatment in a single center. In order to define predictors of vasospasm severity, we studied the demographic and clinical characteristics of these patients. Vasospasm severity was defined by cerebral angiography, transcranial Doppler ultrasound, and therapeutic response on endovascular treatment. Statistical analyses were performed to determine significant predictors. RESULTS A total of 70 patients with vasospasm were included. Early onset of mean flow velocities>160 cm/second on transcranial Doppler ultrasound correlated with severity of angiographic vasospasm (P=.0469) and resistance against intra-arterial papaverine (P=.0277). Younger age (<51 years of age) was significantly associated with severity of vasospasm regarding extension on angiography (P=.0422), the need for repetitive endovascular treatment (P=.0084), persistence of transcranial Doppler ultrasound vasospasm after endovascular treatment (P=.0004), and resistance against intra-arterial papaverine (P=.0341). CONCLUSIONS Younger age and early onset of vasospasm on transcranial Doppler ultrasound are important predictors for vasospasm severity. We recommend early and aggressive therapy in this subgroup.

Intracranial aneurysms treated with Guglielmi detachable coils: long-term imaging follow-up with contrast-enhanced magnetic resonance angiography

OBJECT The aim of this study was to assess the long-term results of intracranial aneurysms treated with Guglielmi detachable coils (GDCs) with the aid of contrast-enhanced magnetic resonance (MR) angiography. METHODS Between January 1998 and August 2001, 92 patients with 92 aneurysms treated by endovascular coiling with GDCs underwent contrast-enhanced MR angiography. These patients underwent long-term follow-up (range 32-78 months, mean 42.1 +/- 11.9 months [standard deviation]) after endovascular treatment. All images were compared with digital subtraction angiograms and contrast-enhanced MR angiograms that had been obtained during the short-term follow-up (range 5-25 months, mean 13 +/- 5.1 months after treatment). The MR angiograms were analyzed independently by 2 senior radiologists. Findings were assigned to 1 of 3 categories: complete obliteration (Class 1), residual neck (Class 2), or residual aneurysm (Class 3). RESULTS Of 92 contrast-enhanced MR angiograms obtained at the long-term follow-up, complete obliteration of the aneurysm was noted in 57 patients (Class 1), a residual neck was seen in 22 (Class 2), and a residual aneurysm was observed in 13 (Class 3). One patient experienced aneurysm rehemorrhaging during the follow-up period. The comparison of short- and long-term follow-up angiograms demonstrated a change in aneurysm classification in 7 patients (7.6%), including 4 that progressed from Class 1 to Class 2 and 3 from Class 2 to Class 3. However, 4 (14.2%) of the 28 long-term recurrences were not detected on the short-term control images. CONCLUSIONS Long-term follow-up with contrast-enhanced MR angiography after selective embolization of intracranial aneurysms can identify late aneurysm recanalization that is undetected at short-term follow-up.

Gamma Knife surgery for arteriovenous malformations in the brain: integration of time-resolved contrast-enhanced magnetic resonance angiography into dosimetry planning. Technical note.

OBJECT The aim of this study was to develop an algorithm for the integration of time-resolved contrast-enhanced magnetic resonance (MR) angiography into dosimetry planning for Gamma Knife surgery (GKS) of arteriovenous malformations (AVMs) in the brain. METHODS Twelve patients harboring brain AVMs referred for GKS underwent intraarterial digital subtraction (DS) angiography and time-resolved MR angiography while wearing an externally applied cranial stereotactic frame. Time-resolved MR angiography was performed on a 1.5-tesla MR unit (Achieva, Philips Medical Systems) using contrast-enhanced 3D fast field echo sequencing with stochastic central k-space ordering. Postprocessing with interactive data language (Research Systems, Inc.) produced hybrid data sets containing dynamic angiographic information and the MR markers necessary for stereotactic transformation. Image files were sent to the Leksell GammaPlan system (Elekta) for dosimetry planning. RESULTS Stereotactic transformation of the hybrid data sets containing the time-resolved MR angiography information with automatic detection of the MR markers was possible in all 12 cases. The stereotactic coordinates of vascular structures predefined from time-resolved MR angiography matched with DS angiography data in all cases. In 10 patients dosimetry planning could be performed based on time-resolved MR angiography data. In two patients, time-resolved MR angiography data alone were considered insufficient. The target volumes showed a notable shift of centers between modalities. CONCLUSIONS Integration of time-resolved MR angiography data into the Leksell GammaPlan system for patients with brain AVMs is feasible. The proposed algorithm seems concise and sufficiently robust for clinical application. The quality of the time-resolved MR angiography sequencing needs further improvement.

Subarachnoid Hemorrhage from Spontaneous Dissection of the Anterior Cerebral Artery

1 Takahashi S, Suga T, Kawata Y, Sakamoto K: Anterior choroidal artery: angiographic analysis of variants and anomalies. AJNR Am J Neuroradiol 1990; 11: 719–729. 2 Takahashi M, Arii H, Tamakawa Y: Anomalous arterial supply of temporal and occipital lobes by anterior choroidal artery: angiographic study. AJNR Am J Neuroradiol 1980; 1: 537–540. 3 Von Mitterwallner F: Variationsstatistische Untersuchungen an den basalen Hirngefaessen. Acta Anat (Basel) 1955; 24: 51–87. 4 Chen C, Barkovich AJ: A hyperplastic anterior choroidal artery with double persistent anastamotic channels. AJNR Am J Neuroradiol 1998; 19: 1758–1760. 5 Buxton PJ, Cook PL: Anomalous origin of the parieto-occipital artery: case note. Neuroradiology 1993; 35: 212. 6 Furuno M, Yamakawa N, Okada M, Waga S: Anomalous origin of the calcarine artery. Neuroradiology 1995; 37: 658. 7 Blackburn IW: Anomalies of the encephalic arteries among the insane. J Comp Neurol Psychol 1907; 17: 493–517. Max Wintermark, University of California, San Francisco Department of Radiology, Neuroradiology Section 505 Parnassus Avenue, Box 0628 San Francisco, CA 94143-0628 (USA) Tel. +1 415 353 1639, Fax +1 415 353 8593 E-Mail Max.Wintermark@radiology.ucsf.edu Fig. 4. a Type 3 Takahashi anomaly. A hyperplastic AChorA supplies the parietooccipital and calcarine branches, while the PCA proper gives rise to the temporal branches. b Type 4 Takahashi anomaly. The PCA territory is almost completely fed by a hyperplastic AChorA arising from the ICA.