Faculty Bibliography
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105
Automated CT Perfusion for Ischemic Core Volume Prediction in Tandem Anterior Circulation Occlusions
BACKGROUND/AIM: CT perfusion (CTP) predicts ischemic core volumes in acute ischemic stroke (AIS); however, assumptions made within the pharmacokinetic model may engender errors by the presence of tracer delay or dispersion. We aimed to evaluate the impact of hemodynamic disturbance due to extracranial anterior circulation occlusions upon the accuracy of ischemic core volume estimation with an automated perfusion analysis tool (RAPID) among AIS patients with large-vessel occlusions. METHODS: A prospectively collected, interventional database was retrospectively reviewed for all cases of endovascular treatment of AIS between September 2010 and March 2015 for patients with anterior circulation occlusions with baseline CTP and full reperfusion (mTICI3). RESULTS: Out of 685 treated patients, 114 fit the inclusion criteria. Comparison between tandem (n = 21) and nontandem groups (n = 93) revealed similar baseline ischemic core (20 +/- 19 vs. 19 +/- 25 cm(3); p = 0.8), Tmax >6 s (175 +/- 109 vs. 162 +/- 118 cm(3); p = 0.6), Tmax >10 s (90 +/- 84 vs. 90 +/- 91 cm(3); p = 0.9), and final infarct volumes (45 +/- 47 vs. 37 +/- 45 cm(3); p = 0.5). Baseline core volumes were found to correlate with final infarct volumes for the tandem (r = 0.49; p = 0.02) and nontandem (r = 0.44; p < 0.01) groups. The mean absolute difference between estimated core and final infarct volume was similar between patients with and those without (24 +/- 41 vs. 17 +/- 41 cm(3); p = 0.5) tandem lesions. CONCLUSIONS: The prediction of baseline ischemic core volumes through an optimized CTP analysis employing rigorous normalization, thresholding, and voxel-wise analysis is not significantly influenced by the presence of underlying extracranial carotid steno-occlusive disease in large-vessel AIS.
PMCID:4934474
PMID: 27610125
ISSN: 1664-9737
CID: 2281822
Infarct growth despite full reperfusion in endovascular therapy for acute ischemic stroke
AIM: To explore the predictors of infarct core expansion despite full reperfusion after intra-arterial therapy (IAT). METHODS: We retrospectively reviewed 604 consecutive patients who underwent IAT for anterior circulation large vessel occlusion acute ischemic stroke in two tertiary centers (2008-2013/2010-2013). Sixty patients selected by MRI or CT perfusion presenting within <24 h of onset with modified Thrombolysis In Cerebral Infarction (mTICI) grade 3 or 2c reperfusion were included. Significant infarct growth (SIG) was defined as infarct expansion >11.6 mL. RESULTS: Mean age was 67.0+/-13.7 years, 56% were men. Mean National Institute of Health Stroke Scale (NIHSS) score was 16.2+/-6.1, time from onset to puncture was 6.8+/-3.1 h, and procedure length was 1.3+/-0.6 h. MRI was used for baseline core analysis in 43% of patients. Mean baseline infarct volume was 17.1+/-19.1 mL, absolute infarct growth was 30.6+/-74.5 mL, and final infarct volume was 47.7+/-77.7 mL. Overall, 35% of patients had SIG. Three of 21 patients (14%) treated with stent-retrievers had SIG compared with 14 of 39 (36%) with first-generation devices. Eight of 21 patients (38%) with intravenous tissue plasminogen activator (IV t-PA) had infarct growth compared with 25/39 (64%) without. 23% of patients with SIG had a modified Rankin Scale score
PMID: 25540178
ISSN: 1759-8486
CID: 1984072
Large Volumes of Critically Hypoperfused Penumbral Tissue Do Not Preclude Good Outcomes After Complete Endovascular Reperfusion: Redefining Malignant Profile
BACKGROUND AND PURPOSE: Acute ischemic stroke patients with large volumes of severe hypoperfusion (Tmax>10 s>100 mL) on magnetic resonance imaging have a higher likelihood of intracranial hemorrhage and poor outcomes after reperfusion. We aim to evaluate the impact of the extent of Tmax>10 s CTP lesions in patients undergoing successful treatment. METHODS: Retrospective database review of endovascular acute ischemic stroke treatment between September 2010 and March 2015 for patients with anterior circulation occlusions with baseline RAPID CTP and full reperfusion (mTICI 3). The primary outcome was the impact of the Tmax>10 s lesion spectrum on infarct growth. Secondary safety and efficacy outcomes included parenchymal hematomas and good clinical outcomes (90-day modified Rankin Scale score, 0-2). RESULTS: Of 684 treated patients, 113 patients fit the inclusion criteria. Tmax>10 s>100 mL patients (n=37) had significantly higher baseline National Institutes of Health Stroke Scale (20.7+/-3.8 versus 17.0+/-5.9; P<0.01), more internal carotid artery terminus occlusions (29% versus 9%; P=0.02), and larger baseline (38.6+/-29.6 versus 11.7+/-15.8 mL; P<0.01) and final (60.7+/-60.0 versus 29.4+/-33.9 mL; P<0.01) infarct volumes when compared with patients without Tmax>10 s>100 mL (n=76); however, the 2 groups were otherwise well balanced. There were no significant differences in infarct growth (22.1+/-51.6 versus 17.8+/-32.4 mL; P=0.78), severe intracranial hemorrhage (PH2: 2% versus 4%; P=0.73), good outcomes (90-day mRS score, 0-2: 56% versus 59%; P=0.83), or 90-day mortality (16% versus 7%; P=0.28). On multivariate analysis, only baseline National Institutes of Health Stroke Scale (odds ratio, 1.19; 95% confidence interval, 1.06-1.34; P<0.01) and baseline infarct core volume (odds ratio, 1.05; 95% confidence interval, 1.02-1.08; P<0.01) were independently associated with Tmax>10 s>100 mL. There was no association between Tmax>10 s>100 mL with any PH, good outcome, or infarct growth. CONCLUSIONS: In the setting of limited baseline ischemic cores, large Tmax>10 s lesions on computed tomographic perfusion do not seem to be associated with a higher risk of parenchymal hematomas and do not preclude good outcomes in patients undergoing endovascular reperfusion with contemporary technology.
PMID: 26604248
ISSN: 1524-4628
CID: 1984092
Utility of double inversion recovery MRI in paediatric epilepsy
Detecting focal abnormalities in MRI examinations of children with epilepsy can be a challenging task given the frequently subtle appearance of cortical dysplasia, mesial temporal sclerosis and similar lesions. In this report, we demonstrate the utility of double inversion recovery MRI in the detection of paediatric epileptogenic abnormalities, promoted primarily by increased lesion conspicuity due to complementary suppression of both cerebrospinal fluid and normal white matter signal.
PMCID:4985945
PMID: 26529229
ISSN: 1748-880x
CID: 1984082
Endovascular Therapy for Large Vessel Stroke in the Elderly: Hope in the New Stroke Era
BACKGROUND AND PURPOSE: Acute ischemic stroke (AIS) in the elderly encompasses approximately one-third of all AIS cases. Outcome data have been for the most part discouraging in this population. We aim to evaluate the outcomes in a large contemporary series of elderly patients treated with thrombectomy. METHODS: Retrospective analysis of a single-center endovascular database for consecutive elderly (>/=80 years) patients treated for anterior circulation large vessel occlusion AIS between September 2010 and April 2015. Univariate- and multivariate analyses were performed to identify the predictors of good clinical outcome (90-day modified Ranking Scale [mRS] /=8). The rates of successful reperfusion (modified treatment in cerebral ischemia >/=2b), symptomatic intracranial hemorrhage and 90-day mortality were 80%, 7% and 41%, respectively. The overall rate of good outcome was 29% (n = 32/111) but was 52% (n = 13/25) in patients with baseline mRS score of 0-2 who were selected based on CT perfusion and treated with stent retrievers. On multivariate analysis, only ASPECTS (OR 2.17; 95% CI 1.28-3.67.7; p = 0.004) and baseline NIHSS score (OR 0.87; 95% CI 0.77-0.97; p = 0.013) were independently associated with good outcome. A FIV
PMID: 27454483
ISSN: 1421-9786
CID: 2281852
Magnetic Resonance Imaging in Ischemic Stroke and Cerebral Venous Thrombosis
Imaging is indispensable in the evaluation of patients presenting with central nervous system emergencies. Although computed tomography (CT) is the mainstay of initial assessment and triage, magnetic resonance imaging (MRI) has become vital in expanding diagnostic capabilities, refining management strategies, and developing our understanding of disease processes. Ischemic stroke and cerebral venous thrombosis are 2 areas wherein MRI is actively revolutionizing patient care. Familiarity with the imaging manifestations of these 2 disease processes is crucial for any radiologist reading brain MR studies. In this review, the fundamentals of image interpretation will be addressed in-depth. Furthermore, advanced imaging techniques which are redefining the role of emergency MRI will be outlined, with a focus on the pathophysiological mechanisms that underlie image interpretation. In particular, emerging data surrounding the use of MR perfusion imaging in acute stroke management portend dramatic shifts in neurointerventional management. To this end, a review of the recent stroke literature will hopefully enhance the radiologist's role in both meaningful reporting and multidisciplinary teamwork.
PMID: 26636639
ISSN: 1536-1004
CID: 1984112
Stent-Retriever Thrombectomy for Stroke [Letter]
PMID: 26352820
ISSN: 1533-4406
CID: 2282162
Performance and Predictive Value of a User-Independent Platform for CT Perfusion Analysis: Threshold-Derived Automated Systems Outperform Examiner-Driven Approaches in Outcome Prediction of Acute Ischemic Stroke
BACKGROUND AND PURPOSE: Treatment strategies in acute ischemic stroke aim to curtail ischemic progression. Emerging paradigms propose patient subselection using imaging biomarkers derived from CT, CTA, and CT perfusion. We evaluated the performance of a fully-automated computational tool, hypothesizing enhancements compared with qualitative approaches. The correlation between imaging variables and clinical outcomes in a cohort of patients with acute ischemic stroke is reported. MATERIALS AND METHODS: Sixty-two patients with acute ischemic stroke and MCA or ICA occlusion undergoing multidetector CT, CTA, and CTP were retrospectively evaluated. CTP was processed on a fully operator-independent platform (RApid processing of PerfusIon and Diffusion [RAPID]) computing automated core estimates based on relative cerebral blood flow and relative cerebral blood volume and hypoperfused tissue volumes at varying thresholds of time-to-maximum. Qualitative analysis was assigned by 2 independent reviewers for each variable, including CT-ASPECTS, CBV-ASPECTS, CBF-ASPECTS, CTA collateral score, and CTA clot burden score. Performance as predictors of favorable clinical outcome and final infarct volume was established for each variable. RESULTS: Both RAPID core estimates, CT-ASPECTS, CBV-ASPECTS, and clot burden score correlated with favorable clinical outcome (P < .05); CBF-ASPECTS and collateral score were not significantly associated with favorable outcome, while hypoperfusion estimates were variably associated, depending on the selected time-to-maximum thresholds. Receiver operating characteristic analysis demonstrated disparities among tested variables, with RAPID core and hypoperfusion estimates outperforming all qualitative approaches (area under the curve, relative CBV = 0.86, relative CBF = 0.81; P < .001). CONCLUSIONS: Qualitative approaches to acute ischemic stroke imaging are subject to limitations due to their subjective nature and lack of physiologic information. These findings support the benefits of high-speed automated analysis, outperforming conventional methodologies while limiting delays in clinical management.
PMID: 25999410
ISSN: 1936-959x
CID: 2281872
Stent-retriever thrombectomy after intravenous t-PA vs. t-PA alone in stroke
BACKGROUND: Among patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, less than 40% regain functional independence when treated with intravenous tissue plasminogen activator (t-PA) alone. Thrombectomy with the use of a stent retriever, in addition to intravenous t-PA, increases reperfusion rates and may improve long-term functional outcome. METHODS: We randomly assigned eligible patients with stroke who were receiving or had received intravenous t-PA to continue with t-PA alone (control group) or to undergo endovascular thrombectomy with the use of a stent retriever within 6 hours after symptom onset (intervention group). Patients had confirmed occlusions in the proximal anterior intracranial circulation and an absence of large ischemic-core lesions. The primary outcome was the severity of global disability at 90 days, as assessed by means of the modified Rankin scale (with scores ranging from 0 [no symptoms] to 6 [death]). RESULTS: The study was stopped early because of efficacy. At 39 centers, 196 patients underwent randomization (98 patients in each group). In the intervention group, the median time from qualifying imaging to groin puncture was 57 minutes, and the rate of substantial reperfusion at the end of the procedure was 88%. Thrombectomy with the stent retriever plus intravenous t-PA reduced disability at 90 days over the entire range of scores on the modified Rankin scale (P<0.001). The rate of functional independence (modified Rankin scale score, 0 to 2) was higher in the intervention group than in the control group (60% vs. 35%, P<0.001). There were no significant between-group differences in 90-day mortality (9% vs. 12%, P=0.50) or symptomatic intracranial hemorrhage (0% vs. 3%, P=0.12). CONCLUSIONS: In patients receiving intravenous t-PA for acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, thrombectomy with a stent retriever within 6 hours after onset improved functional outcomes at 90 days. (Funded by Covidien; SWIFT PRIME ClinicalTrials.gov number, NCT01657461.).
PMID: 25882376
ISSN: 1533-4406
CID: 2282182
Dose Reduction in Contrast-Enhanced Cervical MR Angiography: Field Strength Dependency of Vascular Signal Intensity, Contrast Administration, and Arteriographic Quality
OBJECTIVE: Cervical contrast-enhanced MR angiography (MRA) has proven accurate and superior to noncontrast alternatives. We proposed the systematic investigation of dose reduction in contrast-enhanced MRA, hypothesizing heightened tolerance at 3 T vs 1.5 T. Quantitative and qualitative features were compared between full-dose and 50%-reduced dose examinations at 1.5 T and 3 T. MATERIALS AND METHODS: One hundred eight cervical contrast-enhanced MRA examinations were reviewed for qualitative and quantitative (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) features across four dose-field strength combinations: 1.5 T, 0.05 mmol/kg; 3 T, 0.05 mmol/kg; 1.5 T, 0.1 mmol/kg; and 3 T, 0.1 mmol/kg. Quantitative features were evaluated among the following segments: aortic arch, common carotid arteries, common carotid bifurcations, and cervical internal carotid arteries. A qualitative visual rating scale was applied for the same segments as well as to the vertebral arteries along their proximal (V1), intraforaminal (V2), and distal extraforaminal (V3) courses. Significant between-group differences were reported at p < 0.05. RESULTS: Qualitatively good arteriography was observed in all segments for all protocols. No significant qualitative differences between protocols were noted throughout evaluation of the anterior cervical circulation. Significant qualitative differences were observed only for V2 and V3 segments at half-dose 1.5-T compared with the remaining protocols (p < 0.05). No significant quantitative differences were present between full-dose and dose-reduced 3-T MRA in any segment. At 1.5 T, significant decrement in SNR and CNR at half-dose was present only within the cervical internal carotid artery. CONCLUSION: Dose reduction in cervical contrast-enhanced MRA is feasible at 3 T without significant compromise in arteriographic quality in most segments. Particularly at 3 T, arteriography is quantitatively and qualitatively robust and may be advisable in high-risk patients.
PMID: 26001259
ISSN: 1546-3141
CID: 1984122
