Faculty Bibliography
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105
Journal of the American College of Radiology : JACR. 2017:14(2):231-234.DOI: 10.1016/j.jacr.2016.07.004
Enhancing Workflow Analysis in Acute Stroke Patients Using Radiofrequency Identification and Infrared-based Real-Time Location Systems
PMID: 27577591
ISSN: 1558-349x
CID: 2281832
Endovascular Treatment for Patients With Acute Stroke Who Have a Large Ischemic Core and Large Mismatch Imaging Profile
Importance: Endovascular therapy (ET) is typically not considered for patients with large baseline ischemic cores (irreversibly injured tissue). Computed tomographic perfusion (CTP) imaging may identify a subset of patients with large ischemic cores who remain at risk for significant infarct expansion and thus could still benefit from reperfusion to reduce their degree of disability. Objective: To compare the outcomes of patients with large baseline ischemic cores on CTP undergoing ET with the outcomes of matched controls who had medical care alone. Design, Setting, and Participants: A matched case-control study of patients with proximal occlusion after stroke (intracranial internal carotid artery and/or middle cerebral artery M1 and/or M2) on computed tomographic angiography and baseline ischemic core greater than 50 mL on CTP at a tertiary care center from May 1, 2011, through October 31, 2015. Patients receiving ET and controls receiving medical treatment alone were matched for age, baseline ischemic core volume on CTP, and glucose levels. Baseline characteristics and outcomes were compared. Main Outcomes and Measures: The primary outcome measure was the shift in the degree of disability among the treatment and control groups as measured by the modified Rankin Scale (mRS) (with scores ranging from 0 [fully independent] to 6 [dead]) at 90 days. Results: Fifty-six patients were matched across 2 equally distributed groups (mean [SD] age, 62.25 [13.92] years for cases and 58.32 [14.79] years for controls; male, 13 cases [46%] and 14 controls [50%]). Endovascular therapy was significantly associated with a favorable shift in the overall distribution of 90-day mRS scores (odds ratio, 2.56; 95% CI, 2.50-8.47; P = .04), higher rates of independent outcomes (90-day mRS scores of 0-2, 25% vs 0%; P = .04), and smaller final infarct volumes (mean [SD], 87 [77] vs 242 [120] mL; P < .001). One control (4%) and 2 treatment patients (7%) developed a parenchymal hematoma type 2 (P > .99). The rates of hemicraniectomy (2 [7%] vs 6 [21%]; P = .10) and 90-day mortality (7 [29%] vs 11 [48%]; P = .75) were numerically lower in the intervention arm. Sensitivity analysis for patients with a baseline ischemic core greater than 70 mL (12 pairs) revealed a significant reduction in final infarct volumes (mean [SD], 110 [65] vs 319 [147] mL; P < .001) but only a nonsignificant improvement in the overall distribution of mRS scores favoring the treatment group (P = .18). All 11 patients older than 75 years had poor outcomes (mRS score >3) at 90 days. Conclusions and Relevance: In properly selected patients, ET appears to benefit patients with large core and large mismatch profiles. Future prospective studies are warranted.
PMID: 27820620
ISSN: 2168-6157
CID: 2473352
Body Temperature Modulates Infarction Growth following Endovascular Reperfusion
BACKGROUND AND PURPOSE: The neuronal substrate is highly sensitive to temperature elevation; however, its impact on the fate of the ischemic penumbra has not been established. We analyzed interactions between temperature and penumbral expansion among successfully reperfused patients with acute ischemic stroke, hypothesizing infarction growth and worse outcomes among patients with fever who achieve full reperfusion. MATERIALS AND METHODS: Data from 129 successfully reperfused (modified TICI 2b/3) patients (mean age, 65 +/- 15 years) presenting within 12 hours of onset were examined from a prospectively collected acute ischemic stroke registry. CT perfusion was analyzed to produce infarct core, hypoperfusion, and penumbral mismatch volumes. Final DWI infarction volumes were measured, and relative infarction growth was computed. Systemic temperatures were recorded throughout hospitalization. Correlational and logistic regression analyses assessed the associations between fever (>37.5 degrees C) and both relative infarction growth and favorable clinical outcome (90-day mRS of 37.5 degrees C and relative infarction growth (Kendall tau correlation coefficient = 0.24, P = .002). Odds ratios for favorable clinical outcome suggested a trend toward significance for fever in predicting a 90-day mRS of
PMID: 27758774
ISSN: 1936-959x
CID: 2280462
The Effects of Acetazolamide on the Evaluation of Cerebral Hemodynamics and Functional Connectivity Using Blood Oxygen Level-Dependent MR Imaging in Patients with Chronic Steno-Occlusive Disease of the Anterior Circulation
BACKGROUND AND PURPOSE: Measuring cerebrovascular reactivity with the use of vasodilatory stimuli, such as acetazolamide, is useful for chronic cerebrovascular steno-occlusive disease. The purpose of this study was to evaluate the effects of acetazolamide on the assessment of hemodynamic impairment and functional connectivity by using noninvasive resting-state blood oxygen level-dependent MR imaging. MATERIALS AND METHODS: A 20-minute resting-state blood oxygen level-dependent MR imaging scan was acquired with infusion of acetazolamide starting at 5 minutes after scan initiation. A recently developed temporal-shift analysis technique was applied on blood oxygen level-dependent MR imaging data before and after acetazolamide infusion to identify regions with hemodynamic impairment, and the results were compared by using contrast agent-based DSC perfusion imaging as the reference standard. Functional connectivity was compared with and without correction on the signal by using information from temporal-shift analysis, before and after acetazolamide infusion. RESULTS: Visually, temporal-shift analysis of blood oxygen level-dependent MR imaging data identified regions with compromised hemodynamics as defined by DSC, though performance deteriorated in patients with bilateral disease. The Dice similarity coefficient between temporal-shift and DSC maps was higher before (0.487 +/- 0.150 by using the superior sagittal sinus signal as a reference for temporal-shift analysis) compared with after acetazolamide administration (0.384 +/- 0.107) (P = .006, repeated-measures ANOVA). Functional connectivity analysis with temporal-shift correction identified brain network nodes that were otherwise missed. The accuracy of functional connectivity assessment decreased after acetazolamide administration (P = .015 for default mode network, repeated-measures ANOVA). CONCLUSIONS: Temporal-shift analysis of blood oxygen level-dependent MR imaging can identify brain regions with hemodynamic compromise in relation to DSC among patients with chronic cerebrovascular disease. The use of acetazolamide reduces the accuracy of temporal-shift analysis and network connectivity evaluation.
PMID: 27758776
ISSN: 1936-959x
CID: 2280472
Acetazolamide-augmented dynamic BOLD (aczBOLD) imaging for assessing cerebrovascular reactivity in chronic steno-occlusive disease of the anterior circulation: An initial experience
The purpose of this study was to measure cerebrovascular reactivity (CVR) in chronic steno-occlusive disease using a novel approach that couples BOLD imaging with acetazolamide (ACZ) vasoreactivity (aczBOLD), to evaluate dynamic effects of ACZ on BOLD and to establish the relationship between aczBOLD and dynamic susceptibility contrast (DSC) perfusion MRI. Eighteen patients with unilateral chronic steno-occlusive disease of the anterior circulation underwent a 20-min aczBOLD imaging protocol, with ACZ infusion starting at 5 min of scan initiation. AczBOLD reactivity was calculated on a voxel-by-voxel basis to generate CVR maps for subsequent quantitative analyses. Reduced CVR was observed in the diseased vs. the normal hemisphere both by qualitative and quantitative assessment (gray matter (GM): 4.13% +/- 1.16% vs. 4.90% +/- 0.98%, P = 0.002; white matter (WM): 2.83% +/- 1.23% vs. 3.50% +/- 0.94%, P = 0.005). In all cases BOLD signal began increasing immediately following ACZ infusion, approaching a plateau at ~ 8.5 min after infusion, with the tissue volume of reduced augmentation increasing progressively with time, peaking at 2.60 min (time range above 95% of the maximum value: 0-4.43 min) for the GM and 1.80 min (time range above 95% of the maximum value: 1.40-3.53 min) for the WM. In the diseased hemisphere, aczBOLD CVR significantly correlated with baseline DSC time-to-maximum of the residue function (Tmax) (P = 0.008 for the WM) and normalized cerebral blood flow (P = 0.003 for the GM, and P = 0.001 for the WM). AczBOLD provides a novel, safe, easily implementable approach to CVR measurement in the routine clinical environments. Further studies can establish quantitative thresholds from aczBOLD towards identification of patients at heightened risk of recurrent ischemia and cognitive decline.
PMCID:5137181
PMID: 27942454
ISSN: 2213-1582
CID: 2473342
Selection Paradigms for Large Vessel Occlusion Acute Ischemic Stroke Endovascular Therapy
BACKGROUND:Optimal patient selection methods for thrombectomy in large vessel occlusion stroke (LVOS) are yet to be established. We sought to evaluate the ability of different selection paradigms to predict favorable outcomes. METHODS:Review of a prospectively collected database of endovascular patients with anterior circulation LVOS, adequate CT perfusion (CTP), National Institutes of Health Stroke Scale (NIHSS) ≥10 from September 2010 to March 2016. Patients were retrospectively assessed for thrombectomy eligibility by 4 mismatch criteria: Perfusion-Imaging Mismatch (PIM): between CTP-derived perfusion defect and ischemic core volumes; Clinical-Core Mismatch (CCM): between age-adjusted NIHSS and CTP core; Clinical-ASPECTS Mismatch (CAM-1): between age-adjusted NIHSS and ASPECTS; Clinical-ASPECTS Mismatch (CAM-2): between NIHSS and ASPECTS. Outcome measures were inclusion rates for each paradigm and their ability to predict good outcomes (90-day modified Rankin Scale 0-2). RESULTS:Three hundred eighty-four patients qualified. CAM-2 and CCM had higher inclusion (89.3 and 82.3%) vs. CAM-1 (67.7%) and PIM (63.3%). Proportions of selected patients were statistically different except for PIM and CAM-1 (p = 0.19), with PIM having the highest disagreement. There were no differences in good outcome rates between PIM(+)/PIM(-) (52.2 vs. 48.5%; p = 0.51) and CAM-2(+)/CAM-2(-) (52.4 vs. 38.5%; p = 0.12). CCM(+) and CAM-1(+) had higher rates compared to nonselected counterparts (53.4 vs. 38.7%, p = 0.03; 56.6 vs. 38.6%; p = 0.002). The abilities of PIM, CCM, CAM-1, and CAM-2 to predict outcomes were similar according to the c-statistic, Akaike and Bayesian information criterion. CONCLUSIONS:For patients with NIHSS ≥10, PIM appears to disqualify more patients without improving outcomes. CCM may improve selection, combining a high inclusion rate with optimal outcome discrimination across (+) and (-) patients. Future studies are warranted.
PMID: 28877524
ISSN: 1421-9786
CID: 3070962
Automated CT Perfusion Ischemic Core Volume and Noncontrast CT ASPECTS (Alberta Stroke Program Early CT Score): Correlation and Clinical Outcome Prediction in Large Vessel Stroke
BACKGROUND AND PURPOSE: The semiquantitative noncontrast CT Alberta Stroke Program Early CT Score (ASPECTS) and RAPID automated computed tomography (CT) perfusion (CTP) ischemic core volumetric measurements have been used to quantify infarct extent. We aim to determine the correlation between ASPECTS and CTP ischemic core, evaluate the variability of core volumes within ASPECTS strata, and assess the strength of their association with clinical outcomes. METHODS: Review of a prospective, single-center database of consecutive thrombectomies of middle cerebral or intracranial internal carotid artery occlusions with pretreatment CTP between September 2010 and September 2015. CTP was processed with RAPID software to identify ischemic core (relative cerebral blood flow<30% of normal tissue). RESULTS: Three hundred and thirty-two patients fulfilled inclusion criteria. Median age was 66 years (55-75), median ASPECTS was 8 (7-9), whereas median CTP ischemic core was 11 cc (2-27). Median time from last normal to groin puncture was 5.8 hours (3.9-8.8), and 90-day modified Rankin scale score 0 to 2 was observed in 54%. The correlation between CTP ischemic core and ASPECTS was fair (R=-0.36; P<0.01). Twenty-six patients (8%) had ASPECTS <6 and CTP core 50 cc and ASPECTS >/=6 (29% had modified Rankin scale 0-2, whereas 21% were deceased at 90 days). Moderate correlations between ASPECTS and final infarct volume (R=-0.42; P<0.01) and between CTP ischemic core and final infarct volume (R=0.50; P<0.01) were observed; coefficients were not significantly influenced by the time from stroke onset to presentation. Multivariable regression indicated ASPECTS >/=6 (odds ratio 4.10; 95% confidence interval, 1.47-11.46; P=0.01) and CTP core
PMID: 27507858
ISSN: 1524-4628
CID: 2281842
Effects of Height and Blood Volume on Venous Enhancement After Gadolinium-Based Contrast Administration in MR Venography: A Paradigm Challenge and Implications for Clinical Imaging
OBJECTIVE: The purpose of this study was to analyze quantitative and qualitative effects of estimated blood volume on venous enhancement in patients undergoing cerebral MR venography (MRV) with standard weight-based dosing of a gadolinium-based contrast agent. MATERIALS AND METHODS: Fifty-two patients with normal 1.5-T cerebral MRV findings and contemporaneous height and weight measurements were included. Estimated blood volume was calculated with the Nadler formula for blood volume. Standard weight-based cerebral MRV was performed after administration of gadobenate dimeglumine (0.1 mmol/kg up to 20 mL). Venous enhancement within the superior sagittal sinus, right jugular bulb, and left jugular bulb was measured. Patients were dichotomized on the basis of administration of less than versus a maximum weight-based gadolinium-based contrast dose of 20 mL. Venographic quality was assigned by two neuroradiologists. Correlational and multiple linear regression analyses were performed. RESULTS: Among patients receiving less than the maximum 20 mL of gadolinium, no significant correlations were observed between weight and vascular enhancement (p > 0.05). Significant correlations between height and enhancement were observed in the superior sagittal sinus and left jugular bulb. This finding suggests that differences in estimated blood volume driven by height remain unaccounted for (p < 0.05). With the 20-mL maximal dose, a significant inverse relation was noted between estimated blood volume and contrast enhancement of all vascular segments (p < 0.05). Within all vascular segments, significant correlations were observed between enhancement and user-defined quality scores (p < 0.05). This finding suggests that optimized dosing may affect reader confidence. CONCLUSION: Standard weight-based dosing for cerebral MRV insufficiently accounts for differences in circulating blood volume. An expanded biometric dosing paradigm leveraging readily attainable subject data may mitigate unintended variations in enhancement affecting venography and other clinical imaging modalities.
PMID: 27304717
ISSN: 1546-3141
CID: 2281862
Utilization of Workflow Process Maps to Analyze Gaps in Critical Event Notification at a Large, Urban Hospital
Stroke care is a time-sensitive workflow involving multiple specialties acting in unison, often relying on one-way paging systems to alert care providers. The goal of this study was to map and quantitatively evaluate such a system and address communication gaps with system improvements. A workflow process map of the stroke notification system at a large, urban hospital was created via observation and interviews with hospital staff. We recorded pager communication regarding 45 patients in the emergency department (ED), neuroradiology reading room (NRR), and a clinician residence (CR), categorizing transmissions as successful or unsuccessful (dropped or unintelligible). Data analysis and consultation with information technology staff and the vendor informed a quality intervention-replacing one paging antenna and adding another. Data from a 1-month post-intervention period was collected. Error rates before and after were compared using a chi-squared test. Seventy-five pages regarding 45 patients were recorded pre-intervention; 88 pages regarding 86 patients were recorded post-intervention. Initial transmission error rates in the ED, NRR, and CR were 40.0, 22.7, and 12.0 %. Post-intervention, error rates were 5.1, 18.8, and 1.1 %, a statistically significant improvement in the ED (p < 0.0001) and CR (p = 0.004) but not NRR (p = 0.208). This intervention resulted in measureable improvement in pager communication to the ED and CR. While results in the NRR were not significant, this intervention bolsters the utility of workflow process maps. The workflow process map effectively defined communication failure parameters, allowing for systematic testing and intervention to improve communication in essential clinical locations.
PMCID:4942383
PMID: 26667658
ISSN: 1618-727x
CID: 1984102
Performance of CT ASPECTS and Collateral Score in Risk Stratification: Can Target Perfusion Profiles Be Predicted without Perfusion Imaging?
BACKGROUND AND PURPOSE: Endovascular trials suggest that revascularization benefits a subset of acute ischemic stroke patients with large-artery occlusion and small-core infarct volumes. The objective of our study was to identify thresholds of noncontrast CT-ASPECTS and collateral scores on CT angiography that best predict ischemic core volume thresholds quantified by CT perfusion among patients with acute ischemic stroke. MATERIALS AND METHODS: Fifty-four patients with acute ischemic stroke (<12 hours) and MCA/intracranial ICA occlusion underwent NCCT/CTP during their initial evaluation. CTP analysis was performed on a user-independent platform (RApid processing of PerfusIon and Diffusion), computing core infarct (defined as CBF of <30% normal). A target mismatch profile consisting of infarction core of /=9 with a CTA collateral score of 3 had 100% specificity for identifying patients with a CBF core volume of 50 mL. In our cohort, 44 (81%) patients had an NCCT-ASPECTS of >/=9, a CTA collateral score of 3, or an NCCT-ASPECTS of /=9 or a CTA collateral score of 3 best predicts CBF core volume infarct of 50 mL. Together these thresholds suggest that a specific population of patients with acute ischemic stroke not meeting such profiles may benefit most from CTP imaging to determine candidacy for revascularization.
PMID: 26965466
ISSN: 1936-959x
CID: 2238922
