Stroke onset time determination using MRI relaxation times without non-ischaemic reference in a rat stroke model

Many ischaemic stroke patients are ineligible for thrombolytic therapy due to unknown onset time. Quantitative MRI (qMRI) is a potential surrogate for stroke timing. Rats were subjected to permanent middle cerebral artery occlusion and qMRI parameters including hemispheric differences in apparent diffusion coefficient, T2-weighted signal intensities, T1 and T2 relaxation times (qT1, qT2) and f1, f2 and Voverlap were measured at hourly intervals at 4.7 or 9.4 T. Accuracy and sensitivity for identifying strokes scanned within and beyond 3 h of onset was determined. Accuracy for Voverlap, f2 and qT2 (>90%) was significantly higher than other parameters. At a specificity of 1, sensitivity was highest for Voverlap (0.90) and f2 (0.80), indicating promise of these qMRI indices in the clinical assessment of stroke onset time.

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DETERMINING STROKE ONSET TIME USING QUANTIATIVE MRI: PRELIMINARY EVIDENCE OF AN ADC/QT2 MISMATCH IN ACUTE ISCHAEMIC STROKE PATIENTS

10.26226/morressier.58e389b1d462b802923850c8 ◽

2017 ◽

Author(s):

Bryony McGarry

Keyword(s):

Ischaemic Stroke ◽

Acute Ischaemic Stroke ◽

Onset Time ◽

Preliminary Evidence ◽

Stroke Onset ◽

Stroke Patients

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Intra-domain task-adaptive transfer learning to determine acute ischemic stroke onset time

Computerized Medical Imaging and Graphics ◽

10.1016/j.compmedimag.2021.101926 ◽

2021 ◽

Vol 90 ◽

pp. 101926

Author(s):

Haoyue Zhang ◽

Jennifer S Polson ◽

Kambiz Nael ◽

Noriko Salamon ◽

Bryan Yoo ◽

...

Keyword(s):

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Transfer Learning ◽

Onset Time ◽

Stroke Onset

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Abstract W P32: Association of Low Cerebral Blood Volume With Negative FLAIR Hyperintensity in Acute Ischemic Stroke

Stroke ◽

10.1161/str.45.suppl_1.wp32 ◽

2014 ◽

Vol 45 (suppl_1) ◽

Author(s):

Nandakumar Nagaraja ◽

Marie Luby ◽

Matthew Edwardson ◽

Ramin Zand ◽

Lawrence L Latour

Keyword(s):

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Blood Volume ◽

Early Phase ◽

Cerebral Blood Volume ◽

Time Window ◽

Linear Regression Analysis ◽

Onset Time ◽

Stroke Onset ◽

Imaging Biomarker

Objective: FLAIR hyperintensity is being used in clinical trials as a surrogate imaging biomarker for stroke onset time to test the safety of thrombolysis. Studies have shown that patients with negative and positive FLAIR hyperintensity overlap at similar time points from stroke onset in the early phase of acute ischemic stroke (AIS). Hyperintensity on FLAIR MRI likely represents increased tissue water content. We sought to determine if cerebral blood volume (CBV) mediates FLAIR hyperintensity in the early phase of AIS. Methods: AIS patients seen in 2012 were included in the study if i) onset time was known, ii) an MRI with perfusion was performed within 12 hours of onset time, iii) had imaging confirmed vascular occlusion of ICA, M1, or M2. Following co-registration of raw perfusion images with FLAIR, CBV maps were generated using PMA ASIST™ software. Two raters blinded to clinical information separately evaluated the DWI, FLAIR and CBV maps and measured the signal intensity ratio (SIR) for the brightest region on FLAIR normalized by homologous contra-lateral tissue. The SIR was similarly measured for CBV in same region. FLAIR negative was defined as SIR<1.15, “Low CBV” was defined as CBV SIR <0.5. Results: One hundred eighty two patients were screened and 30 met all study criteria; 21 women, with mean age of 71 (± 16) years and median NIHSS 18 (IQR 9-22). Using linear regression analysis, CBV SIR was associated with FLAIR SIR (p <0.049). In the 0-3hr time window, overall CBV was not associated with FLAIR hyperintensity. However, in the 3-7.5hr time window, patients with negative FLAIR were more likely to have low CBV and conversely, patients with positive FLAIR were more likely to have normal CBV. Conclusion: CBV likely mediates FLAIR hyperintensity in 3-7.5hr of stroke onset but it has less impact on FLAIR hyperintensity in the first 3 hours of AIS. Low CBV could be a potential surrogate imaging biomarker in addition to FLAIR hyperintensity in the early phase of AIS.

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ONSET TIME DETERMINATION OF ACOUSTIC AND ELECTROMAGNETIC EMISSION DURING ROCK FRACTURE

Progress In Electromagnetics Research Letters ◽

10.2528/pierl12070203 ◽

2012 ◽

Vol 35 ◽

pp. 51-62 ◽

Cited By ~ 28

Author(s):

Gianni Niccolini ◽

Jie Xu ◽

Amedeo Manuello ◽

Giuseppe Lacidogna ◽

Alberto Carpinteri

Keyword(s):

Rock Fracture ◽

Onset Time ◽

Electromagnetic Emission ◽

Time Determination

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Fluctuation of serum NOx concentration at stroke onset in a rat spontaneous stroke model (M-SHRSP)

Brain Research ◽

10.1016/s0006-8993(02)02975-x ◽

2002 ◽

Vol 949 (1-2) ◽

pp. 147-156 ◽

Cited By ~ 14

Author(s):

Masaki Tabuchi ◽

Keizo Umegaki ◽

Tomohiro Ito ◽

Motohisa Suzuki ◽

Isao Tomita ◽

...

Keyword(s):

Stroke Onset ◽

Stroke Model

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Reliability of Synthetic Brain MRI for Assessment of Ischemic Stroke with Phantom Validation of a Relaxation Time Determination Method

Journal of Clinical Medicine ◽

10.3390/jcm9061857 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1857

Author(s):

Chia-Wei Li ◽

Ai-Ling Hsu ◽

Chi-Wen C. Huang ◽

Shih-Hung Yang ◽

Chien-Yuan Lin ◽

...

Keyword(s):

Ischemic Stroke ◽

Relaxation Time ◽

Brain Mri ◽

Relaxation Times ◽

Onset Time ◽

Magnetic Resonance Images ◽

Diagnostic Tools ◽

Cupric Sulfate ◽

T2 Relaxation ◽

T1 And T2

The reliability of relaxation time measures in synthetic magnetic resonance images (MRIs) of homemade phantoms were validated, and the diagnostic suitability of synthetic imaging was compared to that of conventional MRIs for detecting ischemic lesions. Phantoms filled with aqueous cupric-sulfate (CuSO4) were designed to mimic spin-lattice (T1) and spin-spin (T2) relaxation properties and were used to compare their accuracies and stabilities between synthetic and conventional scans of various brain tissues. To validate the accuracy of synthetic imaging in ischemic stroke diagnoses, the synthetic and clinical scans of 18 patients with ischemic stroke were compared, and the quantitative contrast-to-noise ratios (CNRs) were measured, using the Friedman test to determine significance in differences. Results using the phantoms showed no significant differences in the interday and intersession synthetic quantitative T1 and T2 values. However, between synthetic and referenced T1 and T2 values, differences were larger for longer relaxation times, showing that image intensities in synthetic scans are relatively inaccurate in the cerebrospinal fluid (CSF). Similarly, CNRs in CSF regions of stroke patients were significantly different on synthetic T2-weighted and T2-fluid-attenuated inversion recovery images. In contrast, differences in stroke lesions were insignificant between the two. Therefore, interday and intersession synthetic T1 and T2 values are highly reliable, and discrepancies in synthetic T1 and T2 relaxation times and image contrasts in CSF regions do not affect stroke lesion diagnoses. Additionally, quantitative relaxation times from synthetic images allow better estimations of ischemic stroke onset time, consequently increasing confidence in synthetic MRIs as diagnostic tools for ischemic stroke.

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Factors that influence clinicians’ decisions to offer intravenous alteplase in acute ischemic stroke patients with uncertain treatment indication: Results of a discrete choice experiment

International Journal of Stroke ◽

10.1177/1747493017690755 ◽

2017 ◽

Vol 13 (1) ◽

pp. 74-82 ◽

Cited By ~ 1

Author(s):

Aoife De Brún ◽

Darren Flynn ◽

Laura Ternent ◽

Christopher I Price ◽

Helen Rodgers ◽

...

Keyword(s):

Decision Making ◽

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Discrete Choice Experiment ◽

Discrete Choice ◽

Choice Experiment ◽

Onset Time ◽

Stroke Onset ◽

Related Factors ◽

Intravenous Alteplase

Background Treatment with intravenous alteplase for eligible patients with acute ischemic stroke is underused, with variation in treatment rates across the UK. This study sought to elucidate factors influencing variation in clinicians’ decision-making about this thrombolytic treatment. Methods A discrete choice experiment using hypothetical patient vignettes framed around areas of clinical uncertainty was conducted with UK-based clinicians. Mixed logit regression analyses were conducted on the data. Results A total of 138 clinicians completed the discrete choice experiment. Seven patient factors were individually predictive of increased likelihood of immediately offering IV alteplase (compared to reference levels in brackets): stroke onset time 2 h 30 min [50 min]; pre-stroke dependency mRS 3 [mRS 4]; systolic blood pressure 185 mm/Hg [140 mm/Hg]; stroke severity scores of NIHSS 5 without aphasia, NIHSS 14 and NIHSS 23 [NIHSS 2 without aphasia]; age 85 [68]; Afro-Caribbean [white]. Factors predictive of withholding treatment with IV alteplase were: age 95 [68]; stroke onset time of 4 h 15 min [50 min]; severe dementia [no memory problems]; SBP 200 mm/Hg [140 mm/Hg]. Three clinician-related factors were predictive of an increased likelihood of offering IV alteplase (perceived robustness of the evidence for IV alteplase; thrombolyzing more patients in the past 12 months; and high discomfort with uncertainty) and one with a decreased likelihood (high clinician comfort with treating patients outside the licensing criteria). Conclusions Both patient- and clinician-related factors have a major influence on the use of alteplase to treat patients with acute ischemic stroke. Clinicians’ views of the evidence, comfort with uncertainty and treating patients outside the license criteria are important factors to address in programs that seek to reduce variation in care quality regarding treatment with IV alteplase. Further research is needed to further understand the differences in clinical decision-making about treating patients with acute ischemic stroke with IV alteplase.

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