Mechanical recanalization in basilar artery occlusion: the ENDOSTROKE study.

OBJECTIVE: A study was undertaken to evaluate clinical and procedural factors associated with outcome and recanalization in endovascular stroke treatment (EVT) of basilar artery (BA) occlusion. METHODS: ENDOSTROKE is an investigator-initiated multicenter registry for patients undergoing EVT. This analysis includes 148 consecutive patients with BA occlusion, with 59% having received intravenous thrombolysis prior to EVT. Recanalization (defined as Thrombolysis in Cerebral Infarction [TICI] score 2b-3) and collateral status (using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology collateral grading system) were assessed by a blinded core laboratory. Good (moderate) outcome was defined as a modified Rankin Scale score of 0 to 2 (0-3) assessed after at least 3 months (median time to follow-up = 120 days). RESULTS: Thirty-four percent had good and 42% had moderate clinical outcome; mortality was 35%. TICI 2b-3 recanalization was achieved by 79%. Age, hypertension, National Institutes of Health Stroke Scale scores, collateral status, and the use of magnetic resonance imaging prior to EVT predicted clinical outcome, the latter 3 remaining independent predictors in multivariate analysis. Independent predictors of recanalization were better collateral status and the use of a stent retriever. However, recanalization did not significantly predict clinical outcome. INTERPRETATION: Beside initial stroke severity, the collateral status predicts clinical outcome and recanalization in BA occlusion. Our data suggest that the use of a stent retriever is associated with high recanalization rates, but recanalization on its own does not predict outcome. The role of other modifiable factors, including the choice of pretreatment imaging modality and time issues, warrants further investigation.

Non-enhanced MR imaging of cerebral aneurysms: 7 Tesla versus 1.5 Tesla.

PURPOSE: To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA). MATERIAL AND METHODS: Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin's concordance correlation coefficient. RESULTS: A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings. CONCLUSION: 7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high-quality diagnostic tool for pretherapeutic assessment and follow-up of untreated UIA.

Age dependency of successful recanalization in anterior circulation stroke: the ENDOSTROKE study.

BACKGROUND: Clinical outcome after endovascular stroke therapy (EVT) for proximal anterior circulation stroke is often disappointing despite high recanalization rates. The ENDOSTROKE study aims to determine predictors of clinical outcome in patients undergoing EVT. Here we focus on the impact of age and recanalization on proximal middle cerebral artery (M1-MCA) or carotid T occlusion. METHODS: ENDOSTROKE is an investigator-initiated, industrially independent multicenter registry launched in January, 2011, for consecutive patients undergoing EVT for large-vessel stroke. This analysis focuses on patients treated in 11 academic and nonacademic stroke centers with angiographically proven M1-MCA (n = 259) or carotid T occlusion (n = 103). Recanalization was defined as Thrombolysis in Myocardial Infarction (TIMI) score 2 or 3, and in patients with available Thrombolysis in Cerebral Ischemia (TICI) data (n = 309) as TICI scores 2b-3. Good outcome was defined as modified Rankin Scale (mRS) score of 0-2 assessed after 3 months or later. RESULTS: The median age was 68 years (25th and 75th percentiles: 56, 76 years), and the median National Institutes of Health Stroke Scale (NIHSS) score at admission was 16 (13, 19); 41% of the patients had a favorable (mRS scores 0-2), and 59% had an unfavorable (mRS scores 3-6) outcome; 83% reached TIMI 2-3 flow. Independent predictors of good outcome were younger age, lower initial NIHSS scores, TIMI 2/3 recanalization and lower serum glucose levels. Outcome was highly dependent on patients' age: 60% of the patients within the lowest age quartile (range: 18-56 years) experienced good clinical outcome, decreasing stepwise over 47% (57-68 years) and 37% (69-76 years) to 17% in the highest age quartile (77-94 years). The proportion of patients with poor clinical outcome despite TIMI 2/3 recanalization ('futile recanalization') increased dramatically from only 29% in the lowest age quartile over 34% and 40% (2nd and 3rd age quartiles) up to 53% in the highest age quartile. Results were similar in patients with available TICI scores, with 'futile recanalization' rates increasing from 24% to 46% (lowest to highest age quartile). CONCLUSIONS: This study emphasizes the dramatic impact of patients' age on outcome in EVT for M1-MCA or carotid T occlusion, even in the presence of recanalization. Reasons for this age-related decrease in clinically successful recanalization rates urgently need clarification and may comprise patient-related factors (age-related increase in cardioembolic strokes, collateral status, comorbidities) as well as periprocedural issues (tortuous vessel anatomy in the elderly, age-dependent negative impact of general anesthesia in EVT).

Isolated cerebral susceptibility artefacts in patients with malignant melanoma: metastasis or not?

OBJECTIVE: While staging patients with malignant melanoma, cerebral susceptibility artefacts on T2*-weighted/susceptibility-weighted imaging (SWI) sequences without a correlate on contrast-enhanced T1-weighted images can be confusing. Without intravenous contrast enhancement, cavernomas, microhaemorrhages and melanin-containing metastases represent possible differential diagnoses for these findings. The purpose of this study was to find out, how often such lesions correspond to metastases. METHODS: Brain MR images (1.5 T) of 408 patients with malignant melanoma but without cerebral metastases in the initial staging by MRI were reviewed retrospectively. Eighteen patients (5 female, 13 male) with malignant melanoma and signal intensity loss on T2*/SWI were included in our study. The average observation period was 19.6 months (6-46 months, 2006-2009). RESULTS: In each of these 18 patients between one and seven hypointense lesions on T2*/SWI were found. None of these lesions developed into metastasis. CONCLUSION: Focal areas of susceptibility artefacts in the brain parenchyma without corresponding abnormalities in contrast-enhanced T1 weighted images are unlikely to represent brain metastases. KEY POINTS: • In melanoma patients early diagnosis of metastatic brain lesions is mandatory. • Melanin content and haemorrhage are potential reasons for MRI characteristics of melanoma metastases. • Susceptibility-weighted MRI visualises melanin and blood products. • Isolated cerebral susceptibility artefacts do not convert into melanoma metastases. • SWI/T2* sequences cannot replace Gd-enhanced sequences.

Caudal image contrast inversion in MPRAGE at 7 Tesla: problem and solution.

RATIONALE AND OBJECTIVES: The magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) sequence regularly shows caudal image contrast inversion at 7 T and therefore reduced clinical applicability. The investigators report the technical source of this problem and present a practical solution. MATERIALS AND METHODS: A total of 71 subjects were scanned using a 7-T whole-body magnetic resonance imaging system using a 32-channel transmit/receive head coil. In 39 subjects, 45 high-resolution T1 contrast image data sets were acquired with the standard MPRAGE sequence. A modified sequence with an adiabatic wideband uniform rate smooth truncation pulse for magnetization preparation was used for 45 further scans in 39 subjects. In total, seven subjects underwent scans with both sequences. The homogeneity of T1 contrast and the occurrence of caudal image contrast inversion were evaluated in consensus reading by two neuroradiologists. RESULTS: Caudal image contrast inversion was depicted in 19 acquisitions (42.2%) using the standard MPRAGE sequence. Using the adiabatic wideband uniform rate smooth truncation pulse for magnetization preparation, caudal image contrast inversion was depicted in only three acquisitions (6.7%). A χ(2) test showed a significant difference between the two preparation pulses (P < .001). CONCLUSIONS: Magnetization preparation with an adiabatic wideband uniform rate smooth truncation pulse in the MPRAGE sequence at 7 T can significantly reduce the occurrence of caudal image contrast inversion and improves signal homogeneity.