Faculty Bibliography
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99
A dual-tuned 17 O/1 H head array for direct brain oximetry at 3 Tesla
PURPOSE/OBJECTIVE:H coil for direct brain oximetry at 3T. METHODS:H images. RESULTS:H structural brain images demonstrated excellent quality and anatomical detail using routine clinical imaging sequence parameters and parallel acceleration. CONCLUSION/CONCLUSIONS:H imaging under standard clinical 3Â T scanning conditions.
PMID: 31593372
ISSN: 1522-2594
CID: 4129612
Peri-procedural stroke or death in stenting of symptomatic severe intracranial stenosis
BACKGROUND AND PURPOSE/OBJECTIVE:There are limited data on predictors of 30-day stroke or death in patients with symptomatic intracranial atherosclerosis (sICAS) undergoing stenting. We aim to determine the factors associated with stroke or death at 30 days in the stenting arm of the SAMMPRIS trial. METHODS:This is a post-hoc analysis of the SAMMPRIS trial including patients who underwent angioplasty/stenting. We compared patient-specific variables, lesion-specific variables, procedure-specific variables, and FDA-approved indications between patients with and without the primary outcome (stroke or death at 30 days). Logistic regression analyses were performed to evaluate associations with the primary outcome. RESULTS:We identified 213 patients, 30 of whom (14.1%) met the primary outcome. Smoking status and lesion length were associated with the primary outcome: the odds of stroke or death for non-smokers versus smokers (adjusted OR 4.46, 95% CI 1.79 to 11.1, p=0.001) and for increasing lesion length in millimeters (adjusted OR 1.20, 95% CI 1.02 to 1.39, p=0.029). These had a modest predictive value: absence of smoking history (sensitivity 66.7%, specificity 65.4%) and lesion length (area under curve 0.606). Furthermore, event rates were not significantly different between patients with and without the FDA-approved indication for stenting (15.9% vs 12%, p=0.437). CONCLUSION/CONCLUSIONS:In SAMMPRIS patients who underwent angioplasty/stenting, neither clinical and neuroimaging variables nor the FDA indication for stenting reliably predicted the primary outcome. Further work in identifying reliable biomarkers of stroke/death in patients with sICAS is needed before considering new clinical trials of stenting. TRIAL REGISTRATION NUMBER/BACKGROUND:SAMMPRIS NCT00576693; Results.
PMID: 31484697
ISSN: 1759-8486
CID: 4067412
Possible Empirical Evidence of Glymphatic System on CT after Endovascular Perforations
INTRODUCTION/BACKGROUND:The glial-lymphatic pathway is a fluid-clearance pathway consisting of a para-arterial route for the flow of cerebrospinal fluid along perivascular spaces and subsequently toward the brain interstitium. In this case series we aim to investigate an empirical demonstration of glymphatic clearance of extravasated iodine following perforation incurred during endovascular therapy on serial CT. METHODS AND RESULTS/RESULTS:Six consecutive cases of endovascular perforation during thrombectomy performed between 2005 and 2018 were retrospectively collected by searching our internal database of total 446 thrombectomies. Two cases were excluded because care was withdrawn shortly following the procedure and no follow-up imaging was available. One case was excluded because a ventricular drain was placed. Three cases were hence included in this analysis. All three cases demonstrated progressive absorption of contrast by the brain parenchyma with eventual contrast disappearance. CONCLUSION/CONCLUSIONS:We described a likely in vivo CT correlate of the glymphatic system in a cohort of patients who sustained intraprocedural extravasation during thrombectomy for acute ischemic stroke.
PMID: 31655242
ISSN: 1878-8769
CID: 4161962
Mild fever as a catalyst for consumption of the ischaemic penumbra despite endovascular reperfusion
Cerebrovascular ischaemia is potentiated by hyperthermia, and even mild temperature elevation has proved detrimental to ischaemic brain. Infarction progression following endovascular reperfusion relates to multiple patient-specific and procedural variables; however, the potential influence of mild systemic temperature fluctuations is not fully understood. This study aims to assess the relationship between systemic temperatures in the early aftermath of acute ischaemic stroke and the loss of at-risk penumbral tissues, hypothesizing consumption of the ischaemic penumbra as a function of systemic temperatures, irrespective of reperfusion status. A cross-sectional, retrospective evaluation of a single-institution, prospectively collected endovascular therapy registry was conducted. Patients with anterior circulation, large vessel occlusion acute ischaemic stroke who underwent initial CT perfusion, and in whom at least four-hourly systemic temperatures were recorded beginning from presentation and until the time of final imaging outcome were included. Initial CT perfusion core and penumbra volumes and final MRI infarction volumes were computed. Systemic temperature indices including temperature maxima were recorded, and pre-defined temperature thresholds varying between 37°C and 38°C were examined in unadjusted and adjusted regression models which included glucose, collateral status, reperfusion status, CT perfusion-to-reperfusion delay, general anaesthesia and antipyretic exposure. The primary outcome was the relative consumption of the penumbra, reflecting normalized growth of the at-risk tissue volume ≥10%. The final study population comprised 126 acute ischaemic stroke subjects (mean 63 ± 14.5 years, 63% women). The primary outcome of penumbra consumption ≥10% occurred in 51 (40.1%) subjects. No significant differences in baseline characteristics were present between groups, with the exception of presentation glucose (118 ± 26.6 without versus 143.1 ± 61.6 with penumbra consumption, P = 0.009). Significant differences in the likelihood of penumbra consumption relating to systemic temperature maxima were observed [37°C (interquartile range 36.5 - 37.5°C) without versus 37.5°C (interquartile range 36.8 - 38.2°C) with penumbra consumption, P = 0.001]. An increased likelihood of penumbra consumption was observed for temperature maxima in unadjusted (odds ratio 3.57, 95% confidence interval 1.65 - 7.75; P = 0.001) and adjusted (odds ratio 3.06, 95% confidence interval 1.33 - 7.06; P = 0.009) regression models. Significant differences in median penumbra consumption were present at a pre-defined temperature maxima threshold of 37.5°C [4.8 ml (interquartile range 0 - 11.5 ml) versus 21.1 ml (0 - 44.7 ml) for subjects not reaching or reaching the threshold, respectively, P = 0.007]. Mild fever may promote loss of the ischaemic penumbra irrespective of reperfusion, potentially influencing successful salvage of at-risk tissue volumes following acute ischaemic stroke.
PMCID:7532660
PMID: 33033801
ISSN: 2632-1297
CID: 4627242
Fast Automatic Detection of Large Vessel Occlusions on CT Angiography
Background and Purpose- Accurate and rapid detection of anterior circulation large vessel occlusion (LVO) is of paramount importance in patients with acute stroke due to the potentially rapid infarction of at-risk tissue and the limited therapeutic window for endovascular clot retrieval. Hence, the optimal threshold of a new, fully automated software-based approach for LVO detection was determined, and its diagnostic performance evaluated in a large cohort study. Methods- For this retrospective study, data were pooled from: 2 stroke trials, DEFUSE 2 (n=62; 07/08-09/11) and DEFUSE 3 (n=213; 05/17-05/18); a cohort of endovascular clot retrieval candidates (n=82; August 2, 2014-August 30, 2015) and normals (n=111; June 6, 2017-January 28, 2019) from a single quaternary center; and code stroke patients (n=501; January 1, 2017-December 31, 2018) from a single regional hospital. All CTAs were assessed by the automated algorithm. Consensus reads by 2 neuroradiologists served as the reference standard. ROC analysis was used to assess diagnostic performance of the algorithm for detection of (1) anterior circulation LVOs involving the intracranial internal carotid artery or M1 segment middle cerebral artery (M1-MCA); (2) anterior circulation LVOs and proximal M2 segment MCA (M2-MCA) occlusions; and (3) individual segment occlusions. Results- CTAs from 926 patients (median age 70 years, interquartile range: 58-80; 422 females) were analyzed. Three hundred ninety-five patients had an anterior circulation LVO or M2-MCA occlusion (National Institutes of Health Stroke Scale 14 [median], interquartile range: 9-19). Sensitivity and specificity were 97% and 74%, respectively, for LVO detection, and 95% and 79%, respectively, when M2 occlusions were included. On analysis by occlusion site, sensitivities were 90% (M2-MCA), 97% (M1-MCA), and 97% (intracranial internal carotid artery) with corresponding area-under-the-ROC-curves of 0.874 (M2), 0.962 (M1), and 0.997 (intracranial internal carotid artery). Conclusions- Intracranial anterior circulation LVOs and proximal M2 occlusions can be rapidly and reliably detected by an automated detection tool, which may facilitate intra- and inter-instutional workflows and emergent imaging triage in the care of patients with stroke.
PMID: 31679501
ISSN: 1524-4628
CID: 4172022
Automated Detection of Intracranial Large Vessel Occlusions on Computed Tomography Angiography
Background and Purpose- Endovascular thrombectomy is highly effective in acute ischemic stroke patients with an anterior circulation large vessel occlusion (LVO), decreasing morbidity and mortality. Accurate and prompt identification of LVOs is imperative because these patients have large volumes of tissue that are at risk of infarction without timely reperfusion, and the treatment window is limited to 24 hours. We assessed the accuracy and speed of a commercially available fully automated LVO-detection tool in a cohort of patients presenting to a regional hospital with suspected stroke. Methods- Consecutive patients who underwent multimodal computed tomography with thin-slice computed tomography angiography between January 1, 2017 and December 31, 2018 for suspected acute ischemic stroke within 24 hours of onset were retrospectively identified. The multimodal computed tomographies were assessed by 2 neuroradiologists in consensus for the presence of an intracranial anterior circulation LVO or M2-segment middle cerebral artery occlusion (the reference standard). The patients' computed tomography angiographies were then processed using an automated LVO-detection algorithm (RAPID CTA). Receiver-operating characteristic analysis was used to determine sensitivity, specificity, and negative predictive value of the algorithm for detection of (1) an LVO and (2) either an LVO or M2-segment middle cerebral artery occlusion. Results- CTAs from 477 patients were analyzed (271 men and 206 women; median age, 71; IQR, 60-80). Median processing time was 158 seconds (IQR, 150-167 seconds). Seventy-eight patients had an anterior circulation LVO, and 28 had an isolated M2-segment middle cerebral artery occlusion. The sensitivity, negative predictive value, and specificity were 0.94, 0.98, and 0.76, respectively for detection of an intracranial LVO and 0.92, 0.97, and 0.81, respectively for detection of either an intracranial LVO or M2-segment middle cerebral artery occlusion. Conclusions- The fully automated algorithm had very high sensitivity and negative predictive value for LVO detection with fast processing times, suggesting that it can be used in the emergent setting as a screening tool to alert radiologists and expedite formal diagnosis.
PMID: 31495328
ISSN: 1524-4628
CID: 4080042
Radiological Management of Angiographically Negative, Spontaneous Intracranial Subarachnoid Hemorrhage: A Multicenter Study of Utilization and Diagnostic Yield
BACKGROUND:The optimal diagnostic evaluation for patients with angiographically negative subarachnoid hemorrhage (AN-SAH) remains controversial. OBJECTIVE:To assess the utilization rate and diagnostic yield of imaging tests routinely obtained in identifying a structural cause for AN-SAH. METHODS:In this retrospective multicenter study, consecutive adult patients admitted with nontraumatic, AN-SAH between 01/2010 and 12/2015 were included. Patients with intraparenchymal, subdural, or epidural hematomas in addition to SAH were excluded. Outcomes studied included utilization rate, diagnostic yield, and median time from admission for the following imaging tests: initial computed tomography angiography (CTA) and digital subtraction angiography (DSA), brain and cervical spine magnetic resonance imaging (MRI), and any repeat DSA or CTA performed either during initial admission or at long-term follow-up. RESULTS:A total of 752 patients were included (mean age, 53 yr; 54% male). Initial CTA and DSA were performed in 89% and 100% of patients, respectively. Brain MRI was performed in 75% of patients and was positive in 0.7% of cases. Cervical spine MRI was performed in 61% of patients and was positive in 0.2% of cases. Repeat, same-admission follow-up DSA and CTA were performed in 48% and 51% of patients and were positive in 3.3% and 1% of cases, respectively. Delayed follow-up DSA and CTA after discharge were performed in 26% and 7% of patients and were positive in 2% and 3.7% of cases, respectively, all with negative prior imaging studies. CONCLUSION/CONCLUSIONS:Cervical spine and brain MRI have extremely low diagnostic yield, both are commonly utilized in patients with AN-SAH; while repeat DSA and CTA are utilized less commonly and have slightly higher diagnostic yield.
PMID: 29850838
ISSN: 1524-4040
CID: 3166052
Cerebral MR oximetry during acetazolamide augmentation: Beyond cerebrovascular reactivity in hemodynamic failure
BACKGROUND:Oxygen extraction fraction (OEF) elevation predicts increased ischemic stroke incidence among patients with carotid steno-occlusive disease, and can be estimated from quantitative susceptibility mapping (QSM) MRI. PURPOSE/OBJECTIVE:To explore QSM oximetry during acetazolamide (ACZ) challenge, hypothesizing that detectable OEF alterations will reflect hemodynamic compromise in unilateral cerebrovascular disease (CVD) patients. STUDY TYPE/METHODS:Retrospective. SUBJECTS/METHODS:Fourteen unilateral CVD patients, and 24 healthy controls (HC). FIELD STRENGTH/SEQUENCE/UNASSIGNED:-weighted images at 3T. ASSESSMENT/RESULTS:We constructed QSM images and R2* maps from multiecho GRE images. QSM-OEF maps were generated from the susceptibility difference between venous blood and background brain tissue. Intrasubject diseased/contralateral hemisphere OEF ratios in the middle cerebral artery (MCA) territories were calculated. Intravascular susceptibility in the straight sinus (SS) and MCA was also measured. STATISTICAL TESTS/UNASSIGNED:The result significance was determined using t-tests and Pearson's correlation. RESULTS:Mean and standard deviation for the patient diseased/contralateral OEF ratios were 1.15 ± 0.14 at baseline and 1.23 ± 0.17 post-ACZ. Disease group R2* ratios were 0.95 ± 0.05 at baseline and 1.03 ± 0.08 post-ACZ. Left/right OEF and R2* ratios for the HC group were 0.98 ± 0.06 and 0.99 ± 0.038, respectively. Susceptibility (ppb) in the SS and MCA in patients was 162.63 ± 35.4 and -22.33 ± 13.70, respectively, at baseline, 124.56 ± 37.43 and -19.27 ± 23.14 post-ACZ. The HC group SS and MCA susceptibility was 146.10 ± 24.79 and -19.59 ± 12.37, respectively. Patient group OEF ratios were greater than 1.0 before and after ACZ challenge (P < 0.01 and < 0.001, respectively, one-sample t-test), and were greater than HC ratios (P < 0.001 unpaired t-test). OEF and R2* ratios increased from baseline to post-ACZ (P = 0.024, 0.004, respectively, paired t-test). Detectable blood oxygenation change was confirmed by finding SS susceptibility decreased from baseline to post-ACZ (P < 0.001, paired t-test), while MCA susceptibility did not change significantly (P = 0.67, paired t-test). DATA CONCLUSION/UNASSIGNED:These results suggest QSM is sensitive to dynamic OEF modulation during hemodynamic augmentation. LEVEL OF EVIDENCE/METHODS:3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018.
PMID: 30390367
ISSN: 1522-2586
CID: 3455492
Age-adjusted infarct volume cut-off for favorable outcome after stroke endovascular therapy [Meeting Abstract]
Background and Aims: Optimal selection paradigms for large vessel occlusion acute stroke (LVOS) endovascular therapy (ET) are yet to be established. Previous studies have shown the benefit of adjusting infarct size to age. We sought to study the impact of age-adjusted final infarct volumes (FIV), a surrogate for pre-reperfusion infarct core, on functional outcomes and determine the ideal thresholds for good outcome discrimination (90-day mRS 0-2).
Method(s): We reviewed our prospectively collected endovascular database at a tertiary care center between 9/2010- 2/2018. All patients that underwent ET for anterior circulation LVOS and achieved full reperfusion (mTICI-3) were included and categorized into 4 age groups: (G1) <60 years, (G2) 60-69, (G3) 70-79 (G4) >=80. Baseline characteristics and outcome parameters were compared. FIV was measured on follow-up MRI or CT within 5 days of treatment. For each group, a FIV-good outcome ROC curve was constructed and Youman Index was used to identify the optimal cut-off.
Result(s): 516 patients were studied (G1:171, G2:130, G3:103, G4:112). The mean FIV was 46+/-64ml and 58% achieved good outcome. Patients with poor outcome had larger FIV in each group (p<0.01 for all). The target FIV cut-off (mL) decreased with increased age: G1:45.7(SE 56%, SP 80%); G2:30.4(SE 63%, SP 75%); G3:20.2(SE 76%, SP 65%); G4:16.9(SE 68%, SP 70%). In multivariate analysis, after adjusting for age, baseline NIHSS, glucose level and FIV, achieving a FIV less than the age-adjusted threshold was an independent predictor of good outcome (aOR:2.75 95% CI [1.43-5.29], p=0.002).
Conclusion(s): Age-adjusted infarct volume represents a strong outcome discriminator substitute and might help refine patient selection for stroke endovascular therapy
Method(s): We reviewed our prospectively collected endovascular database at a tertiary care center between 9/2010- 2/2018. All patients that underwent ET for anterior circulation LVOS and achieved full reperfusion (mTICI-3) were included and categorized into 4 age groups: (G1) <60 years, (G2) 60-69, (G3) 70-79 (G4) >=80. Baseline characteristics and outcome parameters were compared. FIV was measured on follow-up MRI or CT within 5 days of treatment. For each group, a FIV-good outcome ROC curve was constructed and Youman Index was used to identify the optimal cut-off.
Result(s): 516 patients were studied (G1:171, G2:130, G3:103, G4:112). The mean FIV was 46+/-64ml and 58% achieved good outcome. Patients with poor outcome had larger FIV in each group (p<0.01 for all). The target FIV cut-off (mL) decreased with increased age: G1:45.7(SE 56%, SP 80%); G2:30.4(SE 63%, SP 75%); G3:20.2(SE 76%, SP 65%); G4:16.9(SE 68%, SP 70%). In multivariate analysis, after adjusting for age, baseline NIHSS, glucose level and FIV, achieving a FIV less than the age-adjusted threshold was an independent predictor of good outcome (aOR:2.75 95% CI [1.43-5.29], p=0.002).
Conclusion(s): Age-adjusted infarct volume represents a strong outcome discriminator substitute and might help refine patient selection for stroke endovascular therapy
EMBASE:628559260
ISSN: 2396-9881
CID: 4001232
eTICI reperfusion: defining success in endovascular stroke therapy
BACKGROUND:Revascularization after endovascular therapy for acute ischemic stroke is measured by the Thrombolysis In Cerebral Infarction (TICI) scale, yet variability exists in scale definitions. We examined the degree of reperfusion with the expanded TICI (eTICI) scale and association with outcomes in the HERMES collaboration of recent endovascular trials. METHODS:The HERMES Imaging Core, blind to all other data, evaluated angiography after endovascular therapy in HERMES. A battery of TICI scores (mTICI, TICI, TICI2C) was used to define reperfusion of the initial target occlusion defined by non-invasive imaging and conventional angiography. RESULTS:Angiography of 801 subjects was available, including 797 defined by non-invasive imaging (154 internal carotid artery (ICA), 583 M1, 60 M2) and 748 by conventional angiography (195 ICA, 459 M1, 94 M2). Among 729 subjects in whom the reperfusion grade could be established, using eTICI (3=100%, 2C=90-99%, 2b67=67-89%, 2b50=50-66%) of the conventional angiography target occlusion, there were 63 eTICI 3 (9%), 166 eTICI 2c (23%), 218 eTICI 2b67 (30%), 103 eTICI 2b50 (14%), 100 eTICI 2a (14%), 19 eTICI 1 (3%), and 60 eTICI 0 (8%). Modified Rankin Scale shift analyses from baseline to 90 days showed that increasing TICI grades were linked with better outcomes, with significant distinctions between TICI 0/1 versus 2a (p=0.028), 2a versus 2b50 (p=0.017), and 2b50 versus 2b67 (p=0.014). CONCLUSIONS:The benefit of endovascular therapy in HERMES was strongly associated with increasing degrees of reperfusion defined by eTICI. The eTICI metric identified meaningful distinctions in clinical outcomes and may be used in future studies and routine practice.
PMID: 30194109
ISSN: 1759-8486
CID: 5121952
