Publications by authors named "David F Kallmes"

388 Publications

Prevention of Allergic-like Reactions at Repeat CT: Steroid Pretreatment versus Contrast Material Substitution.

Radiology 2021 Aug 3:210490. Epub 2021 Aug 3.

From the Department of Radiology (J.S.M., A.B.K., C.H.H., J.J.S., R.P.H., D.F.K., R.J.M.), Department of Quantitative Health Sciences (N.B.L.), Division of Allergic Diseases (D.E.M.), and Department of Neurosurgery (D.F.K.), Mayo Clinic, 200 1st St SW, Rochester, MN 55905.

Background It is unclear whether steroid premedication is an effective means of preventing repeat allergic-like reactions in high-risk patients with a previous allergic-like reaction to iodinated contrast material (ICM). Purpose To compare the effectiveness of ICM substitution (ie, using iohexol in a patient with a previous iopromide reaction) with 12- and 2-hour steroid premedication for preventing repeat acute allergic-like reactions in high-risk patients. Materials and Methods This retrospective study identified all high-risk (ie, having a previous allergic-like reaction) adult and pediatric patients who underwent a contrast-enhanced CT examination at the institution from June 1, 2009, to May 9, 2017. Prophylactic treatments and repeat reactions were identified using chart review. The effectiveness of prophylactic treatments on repeat reaction rates was examined with multivariable regression models that used generalized estimating equations. Results A total of 1973 high-risk patients who underwent 4360 subsequent ICM-enhanced CT examinations were included. Of the 4360 examinations, a total of 280 allergic-like reactions occurred (6%) in 224 of the 1973 patients (11% of patients), with only 19 of 280 reactions (7%) that were more severe than the previous reaction being demonstrated. After adjustment, patients who received a different ICM with and without steroid premedication had a significantly lower rate of repeat reactions than did patients who received steroid premedication and the same ICM (same ICM and steroid premedication: 80 of 423 examinations [19%]; different ICM and no steroid premedication: 10 of 322 examinations [3%]; odds ratio [OR], 0.14 [95% CI: 0.06, 0.33]; < .001; different ICM and steroid premedication: five of 166 patients [3%]; OR, 0.12 [95% CI: 0.04, 0.36]; < .001). When examining the first scan only, patients who received the same ICM had a similar risk of repeat reactions regardless of whether they received steroid premedication (steroid premedication: 44 of 172 patients [26%] vs no premedication: 73 of 298 patients [25%]; OR, 1.00 [95% CI: 0.64, 1.57]; = .99). Conclusion In this cohort, using an iodinated contrast material (ICM) substitution was more effective for preventing repeat allergic-like reactions than using steroid premedication and the same ICM that caused the previous reaction. © RSNA, 2021 See also the editorial by Davenport and Weinstein in this issue.
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http://dx.doi.org/10.1148/radiol.2021210490DOI Listing
August 2021

Mechanisms of fibrinolysis resistance and potential targets for thrombolysis in acute ischaemic stroke: lessons from retrieved stroke emboli.

Stroke Vasc Neurol 2021 Jul 26. Epub 2021 Jul 26.

Radiology, Mayo Clinic, Rochester, Minnesota, USA.

There has been growing interest and insight into the histological composition of retrieved stroke emboli. One of the main focuses of the stroke clot analysis literature has been the implications of clot composition on mechanical thrombectomy procedures. However, the holy grail of clot analysis may not be in the field of clot-device interaction, but rather, in understanding mechanisms of fibrinolysis resistance. The mechanisms underlying the low response to fibrinolytic therapy, even with the newer, more powerful agents, remain poorly understood. While factors such as embolus size, location and collateral status influence alteplase delivery and recanalisation rates; compositional analyses focused on histological and ultrastructural characteristics offer unique insights into mechanisms of alteplase resistance. In this review, we strive to provide comprehensive review of current knowledge on clot composition and ultrastructural analyses that help explain resistance to fibrinolysis.
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http://dx.doi.org/10.1136/svn-2021-001032DOI Listing
July 2021

Comparison of balloon guide catheters and standard guide catheters for acute ischemic stroke: A systematic review and meta-analysis.

World Neurosurg 2021 Jul 16. Epub 2021 Jul 16.

Nested Knowledge, Inc, 1430 Avon St N, St. Paul, MN, USA; Superior Medical Experts, 1430 Avon St N, St. Paul, MN, USA; Duke University Law School, Durham, NC, USA. Electronic address:

Background: Balloon guide catheters (BGC) are designed to induce flow arrest during mechanical thrombectomy (MT) procedures for acute ischemic stroke due to large vessel occlusion, and have been associated with improved clinical and angiographic outcomes. We conducted a systematic review and meta-analysis evaluating the relative technical and clinical outcomes associated with BGC vs. non-BGC approaches.

Methods: A systematic review of clinical literature using the PubMed database was undertaken to identify multi-arm studies published between 2010 and 2021 reporting the use of BGC versus non-BGC approaches for stroke treatment. Data collected included complete recanalization (Thrombolysis in Cerebral Infarction, TICI), first pass effect (FPE) TICI 3, puncture-to recanalization time, number of endovascular attempts, distal embolization, symptomatic intracerebral hemorrhage (sICH), 90-day modified Rankin Scale (mRS) 0-2, and 90-day mortality. Subgroup analyses assessed the impact of treatment device (stent-retrievers, contact aspiration, combination therapy, and not-specified/other). A random effects model was fit for each outcome measure.

Results: Fifteen studies were included. Compared to non-BGC approaches, patients treated with BGCs had higher odds of TICI 3 (OR=1.57 [95% CI: 1.08; 2.29]) and FPE TICI 3 (OR=3.63 [95% CI: 2.34; 5.62]), reduced puncture-to-revascularization time (MD=-7.8 [95% CI: -13.3; -2.2]), fewer endovascular attempts (MD=-0.47 [95% CI: -0.68; -0.26]), reduced odds of distal emboli (OR=0.34 [95% CI: 0.17; 0.71]) and sICH (OR=0.66 [95% CI: 0.51; 0.86]), higher odds of 90-day mRS 0-2 (OR=1.51 [95% CI: 1.27; 1.79]), and reduced odds of mortality (OR=0.69 [95% CI: 0.57; 0.82]).

Conclusions: BGCs yield superior technical and clinical outcomes while reducing patient complications.
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http://dx.doi.org/10.1016/j.wneu.2021.07.034DOI Listing
July 2021

Letter regarding:How much will a catheter tip expand in aspiration thrombectomy?

J Neurointerv Surg 2021 Jul 7. Epub 2021 Jul 7.

Radiology, Mayo Clinic, Rochester, Minnesota, USA.

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http://dx.doi.org/10.1136/neurintsurg-2021-017856DOI Listing
July 2021

Expected Organizational Costs for Inserting Prevalence Information Into Lumbar Spine Imaging Reports.

J Am Coll Radiol 2021 Jun 30. Epub 2021 Jun 30.

Department of Health Services, University of Washington, Seattle, Washington.

Background: Modifying physician behavior to more closely align with guideline-based care can be challenging. Few effective strategies resulting in appropriate spine-related health care have been reported. The Lumbar Imaging With Reporting of Epidemiology (LIRE) intervention did not result in reductions in spine care but did in opioid prescriptions written.

Objectives: To estimate organizational resource needs and costs associated with implementing a pragmatic, decision support-type intervention that inserted age- and modality-matched prevalence information for common lumbar spine imaging findings, using site-based resource use data from the LIRE trial.

Research Design: Time and cost estimation associated with implementing the LIRE intervention in a health organization.

Subjects: Providers and patients assessed in the LIRE trial.

Measures: Expected personnel costs required to implement the LIRE intervention.

Results: Annual salaries were converted to daily average per person costs, ranging from $400 to $2,200 per day (base case) for personnel (range: $300-$2,600). Estimated total average cost for implementing LIRE was $5,009 (range: $2,651-$12,020), including conducting pilot testing with providers. Costs associated with a small amount of time for a radiologist (6-12 hours) and imaging-ordering providers (1-8 hours each) account for approximately 75% of the estimated total cost.

Conclusions: The process of implementing an intervention for lumbar spine imaging reports containing age- and modality-appropriate epidemiological benchmarks for common imaging findings required radiologists, imaging-ordering providers, information technology specialists, and limited testing and monitoring. The LIRE intervention seems to be a relatively low-cost, evidence-based, complementary tool that can be easily integrated into the reporting of spine imaging.
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http://dx.doi.org/10.1016/j.jacr.2021.06.010DOI Listing
June 2021

Endoluminal flow diverters in the treatment of sidewall and bifurcation aneurysm: A systematic review and meta-analysis of complications and angiographic outcomes.

Interv Neuroradiol 2021 Jun 22:15910199211026713. Epub 2021 Jun 22.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Background And Aim: The use of endoluminal flow diversion in bifurcation aneurysms has been questioned due to the potential for complications and lower occlusion rates. In this study we assessed outcomes of endovascular treatment of intracranial sidewall and bifurcation aneurysms with flow diverters.

Methods: In July 2020, a literature search for all studies utilizing endoluminal flow diverter treatment for sidewall or bifurcation aneurysms was performed. Data were collected from studies that met our inclusion/exclusion criteria by two independent reviewers and confirmed by a third reviewer. Using random-effects meta-analysis the target outcomes including overall complications (hematoma, ischemic events, minor ischemic stroke, aneurysm rupture, side vessel occlusion, stenosis, thrombosis, transient ischemic stroke, and other complications), perioperative complications, and follow-up (long-term) aneurysm occlusion were intestigated.

Results: Overall, we included 35 studies with 1084 patients with 1208 aneurysms. Of these aneurysms, 654 (54.14%) and 554 (45.86%) were classified as sidewall and bifurcation aneurysm, respectively, based on aneurysm location. Sidewall aneurysms had a similar total complication rate (R) of 27.12% (95% CI, 16.56%-41.09%), compared with bifurcation aneurysms (R, 20.40%, 95% CI, 13.24%-30.08%) (p = 0.3527). Follow-up angiographic outcome showed comparable complete occlusion rates for sidewall aneurysms (R 69.49%; 95%CI, 62.41%-75.75%) and bifurcation aneurysms (R 73.99%; 95% CI, 65.05%-81.31%; p = 0.4328).

Conclusions: This meta-analysis of sidewall and bifurcation aneurysms treated with endoluminal flow diverters demonstrated no significant differences in complications or occlusion rates. These data provide new information that can be used as a benchmark for comparison with emerging devices for the treatment of bifurcation aneurysms.
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http://dx.doi.org/10.1177/15910199211026713DOI Listing
June 2021

L-Arginine reduces downstream vascular contractility after flow-diverting device deployment: A preliminary study in a rabbit model.

Interv Neuroradiol 2021 Jun 12:15910199211025107. Epub 2021 Jun 12.

Department of Radiology, Mayo Clinic Rochester, Rochester, MN, USA.

Background: Flow diverters (FDs) are an effective treatment for intracranial aneurysms, though not free from hemorrhagic complications. A previous study demonstrated increased vascular contractility after FD-implantation as a potential mechanism of distal complications. Our study aimed to investigate whether L-arginine medication affects vascular contractility following FD deployment in a rabbit model.

Methods: FDs were implanted in the aorta of normal rabbits (+FD, n = 10), with sham-operated aorta as controls (n = 5). L-Arginine was given in the drinking water (2.25% L-arginine hydrochloride) of half of the +FD animals (+FD/+Arg). Force contraction vascular contractility studies were performed on the aortic rings proximal and distal to the FD using an organ bath. Total eNOS, eNOS(pS1177), eNOS(pT495), COX-2, and S100A4 were quantified by western analysis on total protein lysates from aortic segments, normalizing to GAPDH.

Results: Mean vascular contractility was 53% higher in distal relative to proximal aortic segments (P = 0.0038) in +FD animals, but were not significantly different in +FD/+Arg animals, or in sham-operated controls. The +FD animals expressed significantly reduced levels of eNOS(pS1177) than sham-operated controls (P = 0.0335), while both the +FD and +FD/+Arg groups had reduced levels of eNOS(pT495) relative to sham-operated controls (P = 0.0331 and P = 0.0311, respectively).

Conclusion: These results suggest that L-arginine medication reduces distal vascular contractility after FD treatment via nitric oxide production and thus might mitigate risk for downstream complications.
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http://dx.doi.org/10.1177/15910199211025107DOI Listing
June 2021

Histological evaluation of acute ischemic stroke thrombi may indicate the occurrence of vessel wall injury during mechanical thrombectomy.

J Neurointerv Surg 2021 May 11. Epub 2021 May 11.

Department of Neurology, Grady Memorial Hospital, Atlanta, Georgia, USA.

Background: Several animal studies have demonstrated that mechanical thrombectomy (MT) for acute ischemic stroke (AIS) may cause vessel wall injury (VWI). However, the histological changes in human cerebral arteries following MT are difficult to determine.

Objective: To investigate the occurrence of VWI during MT by histological and immunohistochemical evaluation of AIS clots.

Methods: As part of the multicenter STRIP registry, 277 clots from 237 patients were analyzed using Martius Scarlett Blue stain and immunohistochemistry for CD34 (endothelial cells) and smooth muscle actin (smooth muscle cells).

Results: MT devices used were aspiration catheters (100 cases), stentriever (101 cases), and both (36 cases). VWI was found in 33/277 clots (12%). There was no significant correlation between VWI and MT device. The degree of damage varied from grade I (mild intimal damage, 24 clots), to grade II (relevant intimal and subintimal damage, 3 clots), and III (severe injury, 6 clots). VWI clots contained significantly more erythrocytes (p=0.006*) and less platelets/other (p=0.005*) than non-VWI clots suggesting soft thrombus material.Thrombolysis correlated with a lower rate of VWI (p=0.04*). VWI cases showed a significantly higher number of passes (2 [1-4] vs 1 [1-3], p=0.028*) and poorer recanalization outcome (p=0.01*) than cases without VWI.

Conclusions: Histological markers of VWI were present in 12% of AIS thrombi, suggesting that VWI might be related to MT. VWI was associated with soft thrombus consistency, higher number of passes and poorer revascularization outcome. There was no significant correlation between VWI and MT device.
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http://dx.doi.org/10.1136/neurintsurg-2021-017310DOI Listing
May 2021

Agreement between neuroimages and reports for natural language processing-based detection of silent brain infarcts and white matter disease.

BMC Neurol 2021 May 11;21(1):189. Epub 2021 May 11.

Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, MA, USA.

Background: There are numerous barriers to identifying patients with silent brain infarcts (SBIs) and white matter disease (WMD) in routine clinical care. A natural language processing (NLP) algorithm may identify patients from neuroimaging reports, but it is unclear if these reports contain reliable information on these findings.

Methods: Four radiology residents reviewed 1000 neuroimaging reports (RI) of patients age > 50 years without clinical histories of stroke, TIA, or dementia for the presence, acuity, and location of SBIs, and the presence and severity of WMD. Four neuroradiologists directly reviewed a subsample of 182 images (DR). An NLP algorithm was developed to identify findings in reports. We assessed interrater reliability for DR and RI, and agreement between these two and with NLP.

Results: For DR, interrater reliability was moderate for the presence of SBIs (k = 0.58, 95 % CI 0.46-0.69) and WMD (k = 0.49, 95 % CI 0.35-0.63), and moderate to substantial for characteristics of SBI and WMD. Agreement between DR and RI was substantial for the presence of SBIs and WMD, and fair to substantial for characteristics of SBIs and WMD. Agreement between NLP and DR was substantial for the presence of SBIs (k = 0.64, 95 % CI 0.53-0.76) and moderate (k = 0.52, 95 % CI 0.39-0.65) for the presence of WMD.

Conclusions: Neuroimaging reports in routine care capture the presence of SBIs and WMD. An NLP can identify these findings (comparable to direct imaging review) and can likely be used for cohort identification.
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http://dx.doi.org/10.1186/s12883-021-02221-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8111708PMC
May 2021

e-ASPECTS software improves interobserver agreement and accuracy of interpretation of aspects score.

Interv Neuroradiol 2021 Apr 14:15910199211011861. Epub 2021 Apr 14.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Introduction: There is increased interest in the use of artificial intelligence-based (AI) software packages in the evaluation of neuroimaging studies for acute ischemic stroke. We studied whether, compared to standard image interpretation without AI, Brainomix e-ASPECTS software improved interobserver agreement and accuracy in detecting ASPECTS regions affected in anterior circulation LVO.

Methods: We included 60 consecutive patients with anterior circulation LVO who had TICI 3 revascularization within 60 minutes of their baseline CT. A total of 16 readers, including senior neuroradiologists, junior neuroradiologists and vascular neurologists participated. Readers interpreted CT scans on independent workstations and assessed final ASPECTS and evaluated whether each individual ASPECTS region was affected. Two months later, readers again evaluated the CT scans, but with assistance of e-ASPECTS software. We assessed interclass correlation coefficient for total ASPECTS and interobserver agreement with Fleiss' Kappa for each ASPECTS region with and without assistance of the e-ASPECTS. We also assessed accuracy for the readers with and without e-ASPECTS assistance. In our assessment of accuracy, ground truth was the 24 hour CT in this cohort of patients who had prompt and complete revascularization.

Results: Interclass correlation coefficient for total ASPECTS without e-ASPECTS assistance was 0.395, indicating fair agreement compared, to 0.574 with e-ASPECTS assistance, indicating good agreement (P < 0.01). There was significant improvement in inter-rater agreement with e-ASPECTS assistance for each individual region with the exception of M6 and caudate. The e-ASPECTS software had higher accuracy than the overall cohort of readers (with and without e-ASPECTS assistance) for every region except the caudate.

Conclusions: Use of Brainomix e-ASPECTS software resulted in significant improvements in inter-rater agreement and accuracy of ASPECTS score evaluation in a large group of neuroradiologists and neurologists. e-ASPECTS software was more predictive of final infarct/ASPECTS than the overall group interpreting the CT scans with and without e-ASPECTS assistance.
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http://dx.doi.org/10.1177/15910199211011861DOI Listing
April 2021

Per pass analysis of thrombus composition retrieved by mechanical thrombectomy.

Interv Neuroradiol 2021 Apr 7:15910199211009119. Epub 2021 Apr 7.

Departments of Radiology and Neurosurgery, Northwestern University, Chicago, IL, USA.

Background And Aim: Mechanical thrombectomy (MT) for large vessel occlusion often requires multiple passes to retrieve the entire thrombus load. In this multi-institutional study we sought to examine the composition of thrombus fragments retrieved with each pass during MT.

Methods: Patients who required multiple passes during thrombectomy were included. Histopathological evaluation of thrombus fragments retrieved from each pass was performed using Martius Scarlet Blue staining and the composition of each thrombus component including RBC, fibrin and platelet was determined using image analysis software.

Results: 154 patients underwent MT and 868 passes was performed which resulted in 263 thrombus fragments retrieval. The analysis of thrombus components per pass showed higher RBC, lower fibrin and platelet composition in the pass 1 and 2 when compared to pass 3 and passes 4 or more combined (P values <0.05). There were no significant differences between thrombus fragments retrieved in pass 1 and pass 2 in terms of RBC, WBC, fibrin, and platelet composition (P values >0.05). Similarly, when each composition of thrombus fragments retrieved in pass 3 and passes 4 or more combined were compared with each other, no significant difference was noted (P values >0.05).

Conclusion: Our findings confirm that thrombus fragments retrieved with each pass differed significantly in histological content. Fragments in the first passes were associated with lower fibrin and platelet composition compared to fragments retrieved in passes three and four or higher. Also, thrombus fragments retrieved after failed pass were associated with higher fibrin and platelet components.
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http://dx.doi.org/10.1177/15910199211009119DOI Listing
April 2021

Immunologic biomarker changes in patients exposed to intravenous iodinated contrast material.

Ann Allergy Asthma Immunol 2021 Jul 27;127(1):135-136. Epub 2021 Mar 27.

Department of Radiology, Mayo Clinic, Rochester, Minnesota. Electronic address:

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http://dx.doi.org/10.1016/j.anai.2021.03.021DOI Listing
July 2021

Intracranial microhemorrhages in the setting of COVID-19: what we know so far.

Neuroradiol J 2021 Mar 26:19714009211004144. Epub 2021 Mar 26.

Department of Radiology, Mayo Clinic, Rochester, USA.

Background: Diffuse intracranial susceptibility abnormalities have recently been described among patients with coronavirus disease 2019 (COVID-19), although prior studies have consisted of case reports and/or series. This brief literature review seeks to compile and catalogue the available data to elucidate characteristic features of such findings.

Materials And Methods: Scientific articles and studies on intracranial microhemorrhages in the setting of COVID-19 were searched on PubMed, Google Scholar, and the Cochrane Library. Included studies described intracranial microbleed(s) on magnetic resonance imaging in patients with COVID-19. If multiple patients were described, only patients with intracranial microhemorrhage on magnetic resonance imaging were included for analysis. Patient demographics, severity of illness (e.g. intensive care unit admission and/or intubation), time from diagnosis of COVID-19 to magnetic resonance imaging, and location(s) of any observed microhemorrhages were noted.

Results: A total of 39 patients with suspected intracranial microhemorrhages have been described in prior studies. The average age of patients was 64.7 years; 21.9% were women. The average time between COVID-19 diagnosis and magnetic resonance imaging was 31.7 days. All patients in the cohort were admitted to critical care and were either intubated or treated with extracorporeal membrane oxygenation during their clinical course. Microhemorrhages were most commonly located in the subcortical/juxtacortical white matter and corpus callosum.

Conclusions: Intracranial microbleeds are a well-documented finding in patients with severe COVID-19, and are most commonly callosal and subcortical/juxtacortical in location.
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http://dx.doi.org/10.1177/19714009211004144DOI Listing
March 2021

Action mechanism of the beveled tip aspiration catheter.

J Neurointerv Surg 2021 Mar 24. Epub 2021 Mar 24.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

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http://dx.doi.org/10.1136/neurintsurg-2021-017531DOI Listing
March 2021

Preclinical testing platforms for mechanical thrombectomy in stroke: a review on phantoms, in-vivo animal, and cadaveric models.

J Neurointerv Surg 2021 Mar 15. Epub 2021 Mar 15.

Neurosurgery, Mayo Clinic, Rochester, Minnesota, USA

Preclinical testing platforms have been instrumental in the research and development of thrombectomy devices. However, there is no single model which fully captures the complexity of cerebrovascular anatomy, physiology, and the dynamic artery-clot-device interaction. This article provides a critical review of phantoms, in-vivo animal, and human cadaveric models used for thrombectomy testing and provides insights into the strengths and limitations of each platform. Articles published in the past 10 years that reported thrombectomy testing platforms were identified. Characteristics of each test platform, such as intracranial anatomy, artery tortuosity, vessel friction, flow conditions, device-vessel interaction, and visualization, were captured and benchmarked against human cerebral vessels involved in large-vessel occlusion stroke. Thrombectomy phantoms have been constructed from silicone, direct 3D-printed polymers, and glass. These phantoms represent oversimplified patient-specific cerebrovascular geometry but enable adequate visualization of devices and clots under appropriate flow conditions. They do not realistically mimic the artery-clot interaction. For the animal models, arteries from swine, canines, and rabbits have been reported. These models can reasonably replicate the artery-clot-device interaction and have the unique value of evaluating the safety of thrombectomy devices. However, the vasculature geometries are substantially less complex and flow conditions are different from human cerebral arteries. Cadaveric models are the most accurate vascular representations but with limited access and challenges in reproducibility of testing conditions. Multiple test platforms should be likely used for comprehensive evaluation of thrombectomy devices. Interpretation of the testing results should take into consideration platform-specific limitations.
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http://dx.doi.org/10.1136/neurintsurg-2020-017133DOI Listing
March 2021

Association between clot composition and stroke origin in mechanical thrombectomy patients: analysis of the Stroke Thromboembolism Registry of Imaging and Pathology.

J Neurointerv Surg 2021 Jul 15;13(7):594-598. Epub 2021 Mar 15.

Neurosurgery, Baptist Medical Center Jacksonville, Jacksonville, Florida, USA.

Background: We retrospectively evaluated the composition of retrieved clots from ischemic stroke patients to study the association between histological composition and stroke etiology METHODS: Consecutive patients enrolled in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) were included in this study. All patients underwent mechanical thrombectomy and retrieved clots were sent to a central core lab for processing. Histological analysis was performed using martius scarlet blue (MSB) staining, and quantification for red blood cells (RBCs), white blood cells (WBCs), fibrin and platelets was performed using Orbit Image Software. A Wilcoxon test was used for continuous variables and χ test for categorical variables.

Results: 1350 patients were included in this study. The overall rate of Thrombolysis In Cerebral Infarction (TICI) 2c/3 was 68%. 501 patients received tissue plasminogen activator (tPA) (37%). 267 patients (20%) had a large artery atherosclerosis (LAA) source, 662 (49%) a cardioembolic (CE) source, 301 (22%) were cryptogenic, and the remainder had other identifiable sources including hypercoagulable state or dissection. LAA thrombi had a higher mean RBC density (46±23% vs 42±22%, p=0.01) and a lower platelet density (24±18% vs 27±18%, p=0.03) than CE thrombi. Clots from dissection patients had the highest mean RBC density (50±24%) while clots from patients with a hypercoagulable state had the lowest mean RBC density (26±21%).

Conclusions: Our study found statistically significant but clinically insignificant differences between clots of CE and LAA etiologies. Future studies should emphasize molecular, proteomic and immunohistochemical characteristics to determine links between clot composition and etiology.
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http://dx.doi.org/10.1136/neurintsurg-2020-017167DOI Listing
July 2021

Trends in Utilization of Preoperative Embolization for Spinal Metastases: A Study of the National Inpatient Sample 2005-2017.

Neurointervention 2021 Mar 4;16(1):52-58. Epub 2021 Feb 4.

Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA.

Purpose: While previous studies have suggested that preoperative embolization of hypervascular spinal metastases may alleviate intraoperative blood loss and improve resectability, trends and driving factors for choosing this approach have not been extensively explored. Therefore, we evaluated the trends and assessed the factors associated with preoperative embolization utilization for spinal metastatic tumors using a national inpatient database.

Materials And Methods: The National Inpatient Sample database of the Healthcare Cost and Utilization Project was queried for patients undergoing surgical resection for spinal metastasis between January 1, 2005 and December 31, 2017. Patients undergoing preoperative embolization were identified; trends in the utilization of preoperative embolization were analyzed using the Cochran-Armitage test. Multivariable regression was conducted to assess factors associated with higher preoperative embolization utilization.

Results: A total of 11,508 patients with spinal metastasis were identified; 105 (0.91%) underwent preoperative embolization. Of those 105 patients, 79 (75.24%) patients had a primary renal cancer, as compared to 1,732 (15.19%) of those who did not undergo preoperative embolization (P<0.001). The majority of patients in the non-preoperative embolization cohort had a primary lung tumor (n=3,562, 31.24%). Additionally, patient comorbidities were similar among the 2 groups (P>0.05). Trends in preoperative embolization indicated an increase of 0.16% (standard error: 0.024%, P<0.001) in utilization per year.

Conclusion: Utilization of preoperative embolization for spinal metastasis is increasing yearly, especially for patients with renal cancer, suggesting that surgeons may increasingly consider embolization before surgical resection for hypervascular tumors. Additionally, the literature has shown the intraoperative and postoperative benefits of this procedure.
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http://dx.doi.org/10.5469/neuroint.2020.00381DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7946559PMC
March 2021

Providing Epidemiological Data in Lumbar Spine Imaging Reports Did Not Affect Subsequent Utilization of Spine Procedures: Secondary Outcomes from a Stepped-Wedge Randomized Controlled Trial.

Pain Med 2021 06;22(6):1272-1280

Clinical Learning, Evidence, and Research Center, University of Washington, Seattle, Washington, USA.

Objective: To evaluate the effect of inserting epidemiological information into lumbar spine imaging reports on subsequent nonsurgical and surgical procedures involving the thoracolumbosacral spine and sacroiliac joints.

Design: Analysis of secondary outcomes from the Lumbar Imaging with Reporting of Epidemiology (LIRE) pragmatic stepped-wedge randomized trial.

Setting: Primary care clinics within four integrated health care systems in the United States.

Subjects: 238,886 patients ≥18 years of age who received lumbar diagnostic imaging between 2013 and 2016.

Methods: Clinics were randomized to receive text containing age- and modality-specific epidemiological benchmarks indicating the prevalence of common spine imaging findings in people without low back pain, inserted into lumbar spine imaging reports (the "LIRE intervention"). The study outcomes were receiving 1) any nonsurgical lumbosacral or sacroiliac spine procedure (lumbosacral epidural steroid injection, facet joint injection, or facet joint radiofrequency ablation; or sacroiliac joint injection) or 2) any surgical procedure involving the lumbar, sacral, or thoracic spine (decompression surgery or spinal fusion or other spine surgery).

Results: The LIRE intervention was not significantly associated with subsequent utilization of nonsurgical lumbosacral or sacroiliac spine procedures (odds ratio [OR] = 1.01, 95% confidence interval [CI] 0.93-1.09; P = 0.79) or any surgical procedure (OR = 0.99, 95 CI 0.91-1.07; P = 0.74) involving the lumbar, sacral, or thoracic spine. The intervention was also not significantly associated with any individual spine procedure.

Conclusions: Inserting epidemiological text into spine imaging reports had no effect on nonsurgical or surgical procedure utilization among patients receiving lumbar diagnostic imaging.
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http://dx.doi.org/10.1093/pm/pnab065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185556PMC
June 2021

A novel rabbit thromboembolic occlusion model.

J Neurointerv Surg 2021 Feb 11. Epub 2021 Feb 11.

Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Background: To develop a preclinical thromboembolic occlusion model for studying revascularization strategies.

Methods: Clot analog with barium sulfate was injected into the distal aorta in 9 New Zealand white rabbits. The situation of aorta occlusion was compared among fibrin-rich (n=4), red blood cell (RBC)-rich (n=3), and whole blood clot analogs (n=2) using digital subtraction angiography. Arterial geometries, histologic features and circumferential stretch of the distal aorta in rabbits were compared with the common carotid artery in swine and the distal internal carotid artery (ICA) in humans. Aspiration thrombectomy and mechanical thrombectomy using a stent retriever were performed in two rabbits.

Results: The aortic bifurcation was occluded after a single delivery of clot in 4 cases. It was occluded after the second clot injection in the 5 remaining rabbits. Fragmentation of RBC-rich clots occurred during clot injection in 2 cases. The mean diameters of the distal aorta and right common iliac artery in rabbits were 3.7±0.4 and 2.8±0.3 mm, respectively; the mean diameters of human ICA, and first and second segments of the middle cerebral artery (M1, M2) were 3.6±0.4, 3.1±0.4, and 2.4±0.4 mm, respectively. Arterial revascularization was achieved in both rabbits. Geometric, mechanical and histological factors of the distal aorta in rabbit were more close to human distal ICA than swine carotid artery.

Conclusion: Arterial occlusion can be achieved at the aortic bifurcation in rabbits, which is comparable to human ICA bifurcation. This thrombectomy model has the potential to be used for testing of thrombectomy devices.
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http://dx.doi.org/10.1136/neurintsurg-2020-017073DOI Listing
February 2021

COVID-19 Imaging: What We Know Now and What Remains Unknown.

Radiology 2021 06 9;299(3):E262-E279. Epub 2021 Feb 9.

From the Department of Radiology, School of Medicine and Public Health, University of Wisconsin, 600 Highland Ave, MC 3252, Madison, WI 53792-3252 (J.P.K.); Department of Diagnostic Imaging, Rhode Island Hospital, and Warren Alpert Medical School, Brown University, Providence, RI (H.B.); Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY (A.B., M.C.); Departments of Radiology and Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY (L.B.H.); Department of Radiology, Mayo Clinic, Rochester, Minn (D.F.K.); Department of Radiology, Massachusetts General Hospital, Boston, Mass (B.P.L.); Department of Medical Imaging, College of Medicine, University of Arizona, Tucson, Ariz (G.R.); and Department of Medicine and Surgery, Scienze Radiologiche, University of Parma, Parma, Italy (N.S.).

Infection with SARS-CoV-2 ranges from an asymptomatic condition to a severe and sometimes fatal disease, with mortality most frequently being the result of acute lung injury. The role of imaging has evolved during the pandemic, with CT initially being an alternative and possibly superior testing method compared with reverse transcriptase-polymerase chain reaction (RT-PCR) testing and evolving to having a more limited role based on specific indications. Several classification and reporting schemes were developed for chest imaging early during the pandemic for patients suspected of having COVID-19 to aid in triage when the availability of RT-PCR testing was limited and its level of performance was unclear. Interobserver agreement for categories with findings typical of COVID-19 and those suggesting an alternative diagnosis is high across multiple studies. Furthermore, some studies looking at the extent of lung involvement on chest radiographs and CT images showed correlations with critical illness and a need for mechanical ventilation. In addition to pulmonary manifestations, cardiovascular complications such as thromboembolism and myocarditis have been ascribed to COVID-19, sometimes contributing to neurologic and abdominal manifestations. Finally, artificial intelligence has shown promise for use in determining both the diagnosis and prognosis of COVID-19 pneumonia with respect to both radiography and CT.
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http://dx.doi.org/10.1148/radiol.2021204522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7879709PMC
June 2021

Effects of Including Epidemiologic Data in Lumbar Spine Imaging Reports on Prescribing Non-Opioid Medications for Pain.

J Gen Intern Med 2021 Feb 8. Epub 2021 Feb 8.

Department of Radiology, School of Medicine, University of Washington, Seattle, WA, USA.

Background: Information on the prevalence of common imaging findings among patients without back pain in spine imaging reports might affect pain medication prescribing for patients with back pain. Prior research on inserting this text suggested a small reduction in opioid prescribing.

Objective: To evaluate the effect of epidemiologic information in spine imaging reports on non-opioid pain medication prescribing for primary care patients with back pain.

Design: Post hoc analysis of the Lumbar Imaging with Reporting of Epidemiology cluster-randomized trial.

Participants: A total of 170,680 patients aged ≥ 18 years from four healthcare systems who received thoracolumbar, lumbar, or lumbosacral spine imaging from 2013 to 2016 and had not received a prescription for non-opioid pain medication in the preceding 120 days.

Intervention: Text of age- and modality-specific epidemiologic benchmarks indicating the prevalence of common findings in people without back pain inserted into thoracolumbar, lumbar, or lumbosacral spine imaging reports at intervention clinics.

Main Measures: Primary outcomes: any non-opioid prescription within 90 days after index imaging, overall, and by sub-class (skeletal muscle relaxants, NSAIDs, gabapentinoids, tricyclic antidepressants, benzodiazepines, duloxetine).

Secondary Outcomes: count of non-opioid prescriptions within 90 days, overall, and by sub-class.

Key Results: The intervention was not associated with the likelihood of patients receiving at least one prescription for new non-opioid pain-related medications, overall (adjusted OR, 1.02; 95% CI, 0.97-1.08) or by sub-class. The intervention was not associated with the number of prescriptions for any non-opioid medication (adjusted incidence rate ratio [IRR], 1.02; 95% CI, 0.99-1.04). However, the intervention was associated with more new prescriptions for NSAIDs (IRR, 1.12) and tricyclic antidepressants (IRR, 1.11).

Conclusions: Inserting epidemiologic text in spine imaging reports had no effect on whether new non-opioid pain-related medications were prescribed but was associated with the number of new prescriptions for certain non-opioid sub-classes.

Trial Registration: ClinicalTrials.gov identifier: NCT02015455.
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http://dx.doi.org/10.1007/s11606-021-06627-6DOI Listing
February 2021

Systematic review and meta-analysis of current rates of first pass effect by thrombectomy technique and associations with clinical outcomes.

J Neurointerv Surg 2021 Mar 13;13(3):212-216. Epub 2021 Jan 13.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Background: First pass effect (FPE) in mechanical thrombectomy is thought to be associated with good clinical outcomes.

Objective: To determine FPE rates as a function of thrombectomy technique and to compare clinical outcomes between patients with and without FPE.

Methods: In July 2020, a literature search on FPE (defined as modified Thrombolysis in Cerebral Infarction (TICI) 2c-3 after a single pass) and modified FPE (mFPE, defined as TICI 2b-3 after a single pass) and mechanical thrombectomy for stroke was performed. Using a random-effects meta-analysis, we evaluated the following outcomes for both FPE and mFPE: overall rates, rates by thrombectomy technique, rates of good neurologic outcome (modified Rankin Scale score ≤2 at day 90), mortality, and symptomatic intracerebral hemorrhage (sICH) rate.

Results: Sixty-seven studies comprising 16 870 patients were included. Overall rates of FPE and mFPE were 28% and 45%, respectively. Thrombectomy techniques shared similar FPE (p=0.17) and mFPE (p=0.20) rates. Higher odds of good neurologic outcome were found when we compared FPE with non-FPE (56% vs 41%, OR=1.78) and mFPE with non-mFPE (57% vs 44%, OR=1.73). FPE had a lower mortality rate (17% vs 25%, OR=0.62) than non-FPE. FPE and mFPE were not associated with lower sICH rate compared with non-FPE and non-mFPE (4% vs 18%, OR=0.41 for FPE; 5% vs 7%, OR=0.98 for mFPE).

Conclusions: Our findings suggest that approximately one-third of patients achieve FPE and around half of patients achieve mFPE, with equivalent results throughout thrombectomy techniques. FPE and mFPE are associated with better clinical outcomes.
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http://dx.doi.org/10.1136/neurintsurg-2020-016869DOI Listing
March 2021

Gadolinium retention within multiple rat organs after intra-articular administration of gadolinium-based contrast agents.

Skeletal Radiol 2021 Jul 6;50(7):1419-1425. Epub 2021 Jan 6.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.

Objective: To characterize the extent of retention and biodistribution of gadolinium (Gd) following intra-articular (IA) injection of linear and macrocyclic gadolinium-based contrast agents (GBCAs) into the knee joint of a rat model.

Materials And Methods: Fifteen Wistar rats were divided into five groups and underwent fluoroscopically-guided injections of both knee joints of (1) clinical 1:200 dilution (low dose, LD) gadodiamide (linear GBCA), (2) LD gadobutrol (macrocyclic GBCA), (3) undiluted (high dose, HD) gadodiamide, (4) HD gadobutrol, and (5) saline. Gd concentrations were quantified by inductively coupled plasma mass spectrometry in (1) blood and urine samples obtained over a 72 h period and (2) knee joint tissues, brain, kidney, and bone marrow at 3 days post-injection.

Results: Both HD and LD gadodiamide and gadobutrol were rapidly absorbed from the joint with peak serum and urine concentration at 1 h post-injection, with relatively faster clearance of gadobutrol. All GBCA-exposed groups had detectable levels of Gd in the joint tissues, bone marrow, and/or kidneys (median tissue gadolinium range: 0.1-71 μg Gd/g tissue), with higher amounts observed with gadodiamide versus gadobutrol. Retention within brain tissues was only detected following HD gadodiamide administration but not LD gadodiamide nor HD or LD gadobutrol.

Conclusion: There was rapid systemic absorption, redistribution, and widespread multi-organ retention of Gd following IA injection of both linear and macrocyclic GBCAs, despite substantial amounts of urinary excretion. Higher concentrations of Gd were observed with administration of gadodiamide compared to gadobutrol in most tissues and biofluids.
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http://dx.doi.org/10.1007/s00256-020-03695-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8119273PMC
July 2021

High-resolution scanning electron microscopy for the analysis of three-dimensional ultrastructure of clots in acute ischemic stroke.

J Neurointerv Surg 2020 Dec 23. Epub 2020 Dec 23.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Background: Characterization of acute ischemic stroke (AIS) clots has typically focused on two-dimensional histological analysis of the thrombus. The three-dimensional (3D) architecture and distribution of components within emboli have not been fully investigated. The aim of this study was to examine the composition and microstructure of AIS clots using histology and serial block-face scanning electron microscopy (SBFSEM).

Methods: As part of the multi-institutional STRIP registry, 10 consecutive AIS emboli were collected from 10 patients treated by mechanical thrombectomy. Histological and immunohistochemical analysis was performed to determine clot composition. SBFSEM was used to assess the ultrastructural organization of the clots and specific features of individual components.

Results: Quantification of Martius Scarlett Blue stain identified fibrin (44.4%) and red blood cells (RBCs, 32.6%) as the main components. Immunohistochemistry showed a mean platelet and von Willebrand factor content of 23.9% and 11.8%, respectively. The 3D organization of emboli varied greatly depending on the region analyzed. RBC-rich areas were composed mainly of tightly packed RBCs deformed into polyhedrocytes with scant fibrin fibers interwoven between cells. The regions with mixed composition showed thick fibrin fibers along with platelets, white blood cells and RBC clusters. Fibrin-rich areas contained dense fibrin masses with sparse RBC. In three cases, the fibrin formed a grid-like or a sponge-like pattern, likely due to thrombolytic treatment. Segmentation showed that fibrin fibers were thinner and less densely packed in these cases.

Conclusions: 3D-SEM provides novel and potentially clinically relevant information on clot components and ultrastructure which may help to inform thrombolytic treatment and medical device design.
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http://dx.doi.org/10.1136/neurintsurg-2020-016709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8226367PMC
December 2020

Characterizing thrombus with multiple red blood cell compositions by optical coherence tomography attenuation coefficient.

J Biophotonics 2021 03 17;14(3):e202000364. Epub 2020 Dec 17.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Embolectomy is one of the emergency procedures performed to remove emboli. Assessing the composition of human blood clots is an important diagnostic factor and could provide guidance for an appropriate treatment strategy for interventional physicians. Immunostaining has been used to identity compositions of clots as a gold-standard procedure, but it is time-consuming and cannot be performed in situ. Here, we proposed that the optical attenuation coefficient of optical coherence tomography (OCT) can be a reliable indicator as a new imaging modality to differentiate clot compositions. Fifteen human blood clots with multiple red blood cell (RBC) compositions from 21% to 95% were prepared using healthy human whole blood. A homogeneous gelatin phantom experiment and numerical simulation based on the Lambert-Beer's law were examined to verify the validity of the attenuation coefficient estimation. The results displayed that optical attenuation coefficients were strongly correlated with RBC compositions. We reported that attenuation coefficients could be a promising biomarker to guide the choice of an appropriate interventional device in a clinical setting and assist in characterizing blood clots.
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http://dx.doi.org/10.1002/jbio.202000364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8258800PMC
March 2021

Per-pass analysis of acute ischemic stroke clots: impact of stroke etiology on extracted clot area and histological composition.

J Neurointerv Surg 2020 Dec 9. Epub 2020 Dec 9.

Department of Interventional and Diagnostic Neuroradiology, Sahlgrenska University Hospital, Göteborg, Sweden.

Background: Initial studies investigating correlations between stroke etiology and clot composition are conflicting and do not account for clot size as determined by area. Radiological studies have shown that cardioembolic strokes are associated with shorter clot lengths and lower clot burden than non-cardioembolic clots.

Objective: To report the relationship between stroke etiology, extracted clot area, and histological composition at each procedural pass.

Methods: As part of the multi-institutional RESTORE Registry, the Martius Scarlett Blue stained histological composition and extracted clot area of 612 per-pass clots retrieved from 441 patients during mechanical thrombectomy procedures were quantified. Correlations with clinical and procedural details were investigated.

Results: Clot composition varied significantly with procedural passes; clots retrieved in earlier passes had higher red blood cell content (H4=11.644, p=0.020) and larger extracted clot area (H4=10.730, p=0.030). Later passes were associated with significantly higher fibrin (H4=12.935, p=0.012) and platelets/other (H4=15.977, p=0.003) content and smaller extracted clot area. Large artery atherosclerotic (LAA) clots were significantly larger in the extracted clot area and more red blood cell-rich than other etiologies in passes 1-3. Cardioembolic and cryptogenic clots had similar histological composition and extracted clot area across all procedural passes.

Conclusion: LAA clots are larger and associated with a large red blood cell-rich extracted clot area, suggesting soft thrombus material. Cardioembolic clots are smaller in the extracted clot area, consistent in composition and area across passes, and have higher fibrin and platelets/other content than LAA clots, making them stiffer clots. The per-pass histological composition and extracted clot area of cryptogenic clots are similar to those of cardioembolic clots, suggesting similar formation mechanisms.
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http://dx.doi.org/10.1136/neurintsurg-2020-016966DOI Listing
December 2020

Assessment of Blood Clot Composition by Spectral Optical Coherence Tomography: An In Vitro Study.

Neurointervention 2021 Mar 10;16(1):29-33. Epub 2020 Dec 10.

Neuroradiology Research Laboratory, Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Purpose: Optical coherence tomography (OCT) has the potential for in vivo clot composition characterization in difficult mechanical embolectomy cases. We performed an in vitro study to determine the OCT characteristics of red blood cells (RBCs) and fibrin rich clots.

Materials And Methods: Analogues of 5 compositions of clots (5% to 95% RBCs from Group A to E) were created from human blood. The blood mixture was injected into the bifurcation of a 3D printed bifurcated silicone tube. The OPTISTM Integrated System (St. Jude Medical Inc.) was used to identify the magnitude of OCT signals from different compositions of clots. Martius Scarlett Blue trichrome (MSB) staining was performed to confirm the composition of RBCs and fibrin in each clot.

Results: Group A and B showed less signal attenuation (less than 30%) from its surface to the inside, which indicated high penetration (low-back scattering). Group C indicated intermediate signal attenuation (60%) from its surface to inside the clots, in which signals were found even at the periphery of the clot. Group D and E were superficially signal rich with more signal attenuation (more than 80%) from its surface to the inside indicating low penetration (high-back scattering). Signal-free shadowing was shown in 3 clots in Group E. MSB staining indicated color change (from red in fibrin-rich clots to yellow in RBC-rich clots).

Conclusion: Different compositions of clots can be assessed using OCT. Fibrin-rich clots have homogeneous signals with high penetration, while RBC-rich clots can be recognized as superficially signal rich with low penetration.
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http://dx.doi.org/10.5469/neuroint.2020.00297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7946555PMC
March 2021

Cellular responses to flow diverters in a tissue-engineered aneurysm model.

J Neurointerv Surg 2021 Aug 6;13(8):746-751. Epub 2020 Nov 6.

Radiology, Mayo Clinic, Rochester, Minnesota, USA

Background: Notwithstanding the widespread implementation of flow diverters (FDs) in the treatment of intracranial aneurysms, the exact mechanism of action of these devices remains elusive. We aimed to advance the understanding of cellular responses to FD implantation using a 3D tissue-engineered in vitro aneurysm model.

Methods: Aneurysm-like blood vessel mimics (aBVMs) were constructed by electrospinning polycaprolactone nanofibers onto desired aneurysm-like geometries. aBVMs were seeded with human aortic smooth muscle cells (SMCs) followed by human aortic endothelial cells (ECs). FDs were then deployed in the parent vessel of aBVMs covering the aneurysm neck and were cultivated for 7, 14, or 28 days (n=3 for each time point). The EC and SMC coverage in the neck was measured semi-quantitatively.

Results: At day 7, the device segment in contact with the parent vessel was partially endothelialized. Also, the majority of device struts, but not pores, at the parent vessel and neck interface were partially covered with ECs and SMCs, while device struts in the middle of the neck lacked cell coverage. At 14 days, histology verified a neointimal-like lining had formed, partially covering both the struts and pores in the center of the neck. At 28 days, the majority of the neck was covered with a translucent neointimal-like layer. A higher degree of cellular coverage was seen on the struts and pores at the neck at 28 days compared with both 7 and 14 days.

Conclusion: aBVMs can be a valuable alternative tool for evaluating the healing mechanisms of endovascular aneurysm devices.
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http://dx.doi.org/10.1136/neurintsurg-2020-016593DOI Listing
August 2021

Automated Aneurysm Detection: Emerging from the Shallow End of the Deep Learning Pool.

Radiology 2021 01 3;298(1):164-165. Epub 2020 Nov 3.

From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.

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http://dx.doi.org/10.1148/radiol.2020203853DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7771990PMC
January 2021

Characterization of thrombus composition with multimodality CT-based imaging: an in-vitro study.

J Neurointerv Surg 2021 Aug 28;13(8):738-740. Epub 2020 Oct 28.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA

Background: CT is the most commonly used imaging modality for acute ischemic stroke evaluation. There is growing interest to use pre-operative imaging to characterize clot composition in stroke. We performed an in-vitro study examining the ability of various CT techniques in differentiation between different clot types.

Methods: Five clot types with varying fibrin and red blood cells (RBCs) densities (5% RBC and 95% fibrin; 25% RBC and 75% fibrin; 50% RBC and 50% fibrin; 75% RBC and 25% fibrin; 95% RBC and 5% fibrin) were prepared and scanned using various CT scanning protocols (single-energy, dual-energy, photon-counting detector CT, mixed images, and virtual monoenergetic images). Martius Scarlett Blue trichrome staining was performed to confirm the composition of each clot. Mean CT values of each type of clot under different scanning protocol were calculated and compared.

Results: Mean CT values of the CT numbers in the five clot specimens for 5%, 25%, and 50% RBC clot were similar across modalities, and increased significantly for 75% and 95% RBC clots (P<0.0001). Mean CT values are highest in the Mono +50 keV images in each type of clot, and they were also significantly higher than all other imaging protocols (P<0.001). Dual-energy CT with Mono +50 keV images showed the greatest difference between attenuation in each type of clot.

Conclusion: Mono +50 keV dual-energy CT scan may be helpful for differentiating between RBC-rich and fibrin-rich thrombi seen in large-vessel occlusion patients.
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http://dx.doi.org/10.1136/neurintsurg-2020-016799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8079546PMC
August 2021
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