Abstract WP227: Noninvasive Blood Flow Measures in Atherosclerosis of the Posterior Circulation: Quantitative MRA Bests TOF Signal Intensity Ratio in VERiTAS

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
David S Liebeskind ◽  
Shyam Prabhakaran ◽  
Edward Feldmann ◽  
Xinjian Du ◽  
Linda Rose-Finnell ◽  
...  
Keyword(s):  
Signal Intensity ◽  
Intensity Ratio ◽  
Atherosclerotic Lesion ◽  
Posterior Circulation ◽  
Anatomical Landmarks ◽  
Signal Intensity Ratio ◽  
Fractional Flow ◽  
Stenotic Lesion ◽  
Tof Mra ◽  
Clinical Events

Background: Fractional flow across an atherosclerotic lesion measured with TOF-MRA signal intensity ratio (SIR) may be used to gauge hemodynamic severity and to predict subsequent stroke. The degree of flow impairment may also be ascertained by quantitative MRA (QMRA). We analyzed performance of these noninvasive imaging parameters to estimate risk of subsequent posterior circulation events in VERiTAS. Methods: TOF-MRA data and QMRA were simultaneously acquired in VERiTAS. SIR were derived from TOF source images and normalized for analysis with volume flow ratios (VFR) on QMRA at standard anatomical landmarks and across the maximal stenosis. Statistics analyzed the correlation between SIR and VFR, and the ability of each to predict clinical events. Results: 72 subjects (mean age 65.6±10.3 years, 32 (44%) women) with posterior circulation atherosclerosis were enrolled in VERiTAS. Posterior communicating artery (PCOMM) flow to the posterior circulation was detected in 85% on the right, in 86% on the left, with bilateral PCOMM flow in 78%. Fractional flow measures or SIR across the maximal stenotic lesion evident on TOF MRA was reduced in 43%, increased in 16%, with no change in 40%. SIR from the proximal to distal basilar artery segments increased in 62%, was unchanged in 33% and decreased in 4% of cases. SI and VFR exhibited limited correlation at corresponding arterial segments. QMRA VFR indicative of low distal flow status predicted subsequent clinical events, unlike SIR. Conclusions: Evaluation of hemodynamics in posterior circulation atherosclerosis reveals superiority of QMRA to SIR in prospectively predicting recurrent ischemia. Collateral circulation, tandem disease and unique aspects of vertebrobasilar atherosclerosis likely influence the utility of SIR on TOF MRA.

Abstract WP124: Signal Intensity Ratio Does Not Predict Recurrent Stroke in Patients with Symptomatic Intracranial Atherosclerotic Disease

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Owaiz Ansari ◽  
Rajbeer S Sangha ◽  
Sameer Ansari ◽  
Shyam Prabhakaran
Keyword(s):  
High Risk ◽  
Signal Intensity ◽  
Intensity Ratio ◽  
Stroke Risk ◽  
Recurrent Stroke ◽  
Signal Intensity Ratio ◽  
Single Center ◽  
Tof Mra ◽  
Intracranial Atherosclerotic Disease ◽  
Stenotic Lesions

Background: Symptomatic intracranial atherosclerotic disease (ICAD) is associated with high risk for recurrent stroke. Identification of patients remains a challenge using clinical and radiographic markers. Recent research has identified signal intensity ratio (SIR) across stenotic lesions on time-of-flight magnetic resonance angiography (TOF-MRA) as a novel noninvasive marker of recurrent stroke risk. We sought to externally validate this approach in a single center analysis. Methods: From a prospective observational stroke registry since August 2012, we identified patients with ischemic stroke due to ICAD causing moderate-severe stenosis of the basilar, intracranial vertebral, intracranial internal carotid, or middle cerebral arteries. Using the method described previously, we calculated SIR values across the stenotic lesions corrected for background signal intensity from TOF-MRA performed within 7 days of index stroke admission. Outcomes were prospectively captured by phone interview at 1 and 3 months after stroke. Recurrent stroke was defined by new infarct in the territory of the stenotic artery or absent imaging confirmation, territory-specific clinical symptoms lasting > 24 hours. We evaluated whether baseline SIR values were different between patients with and without recurrent stroke overall and in subgroups by ICAD location. P-value < 0.05 was considered significant. Results: Among 99 consecutive patients with ICAD, 79 (80%) had interpretable MRAs at baseline (mean age 68.4 +11.2 years, 53.2% male, 53.2% black, median NIHSS score 3; 27.7% posterior circulation stenosis). Recurrent stroke occurred in 21.5% and 25.3% of patients at 1 and 3 months, respectively. Median SIR at baseline was 0.86 (interquartile range 0.56-1.04) and was not different those with vs. without recurrent stroke (1-month: 0.79 vs. 0.86, p=0.93; 3-month: 0.79 vs. 0.86, p=0.68). Results were not different by ICAD location. Discussion: In this single center prospective registry, we were unable to validate SIR on time-of-flight MRA as a marker of early recurrent stroke risk in patients with symptomatic ICAD. Further research is needed to identify novel predictors of recurrence in this high-risk cohort.

Comparison of Biomechanical and Anatomical Effects Following Eccentric and Concentric Exertions

2005 ◽  
Vol 49 (14) ◽  
pp. 1287-1291
Author(s):  
Amrish O. Chourasia ◽  
Mary E. Sesto ◽  
Youngkyoo Jung ◽  
Robert S. Howery ◽  
Robert G. Radwin
Keyword(s):  
Signal Intensity ◽  
Intensity Ratio ◽  
Maximum Voluntary Contraction ◽  
Magnetic Resonance Images ◽  
Voluntary Contraction ◽  
Work Place ◽  
Signal Intensity Ratio ◽  
Mechanical Stiffness ◽  
Average Decrease ◽  
Muscle Shortening

Work place exertions may include muscle shortening (concentric) or muscle lengthening (eccentric) contractions. This study investigates the upper limb mechanical properties and magnetic resonance images (MRI) of the involved muscles following submaximal eccentric and concentric exertions. Twelve participants were randomly assigned to perform at 30° per second eccentric or concentric forearm supination exertions at 50% isometric maximum voluntary contraction (MVC) for 30 minutes. Measurement of mechanical stiffness, isometric MVC, localized discomfort and MRI supinator: extensor signal intensity ratio was done before, immediately after, 1 hour after and 24 hours after the bout of exercise. A 53% average decrease in mechanical stiffness after 1 hour was observed for the eccentric group (p< 0.05) compared to a 1% average decrease for the concentric group (p> 0.05). Edema, indicative of swelling, was observed 24 hrs after exercise, with an average increase in the MRI supinator: extensor signal intensity ratio of 36% for the eccentric group and less than 10% for the concentric group (p<0.05).

Abstract T P28: Brain MRI FLAIR Signal Intensity Ratio Is Correlated With Matrix Metalloproteinase-9 Level In Acute Ischemic Stroke

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Ruchira M Jha ◽  
Thomas W Battey ◽  
Ly Pham ◽  
Hannah Irvine ◽  
Karen Furie ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Acute Stroke ◽  
Signal Intensity ◽  
Intensity Ratio ◽  
Brain Mri ◽  
Hemorrhagic Transformation ◽  
Signal Intensity Ratio ◽  
Blood Samples ◽  
The Mean ◽  
Metalloproteinase 9

Introduction: Increased Matrix Metalloproteinase-9 (MMP9) level is associated with symptomatic hemorrhagic transformation (HT) after stroke. Higher risk of HT has also been reported in patients with early FLAIR hyperintensity on brain MRI. Hypothesis: We assessed whether FLAIR hyperintensity is associated with MMP9 levels. Methods: We retrospectively analyzed a cohort of acute stroke subjects who had acute brain MRI images and blood samples within the first 12 hours after onset of stroke. FLAIR hyperintensity was quantitatively assessed using FLAIR signal intensity ratio between the stroke lesion and corresponding normal contralateral hemispheres. For each subject, the FLAIR ratio was generated from the average of 6 regions of interest: 2 white matter and 2 gray matter regions each on 2 separate slices. MMP9 was measured using standard ELISA technique. Univariate and multivariate analyses were used to evaluate the relationship between FR and MMP9 and clinical covariates. Results: 180 subjects had brain MRI and MMP9 available for analysis. MRI occurred within 6 ±3 hours and blood samples were drawn within 7 ± 4 hours from last seen well time. The mean MMP9 level was 238 ± 242 ng/mL and the mean FLAIR ratio was 1.40± 0.23. In univariate analysis, FLAIR ratio was associated with time to MRI (r= 0.18, p=0.01) and MMP9 (r=0.29, p<0.001). In multivariate analysis both FLAIR ratio (p<0.001) and time to MRI (p=0.003) remained associated with MMP9. Conclusions: There is a significant association between FLAIR ratio and MMP9 in acute stroke subjects. This raises the possibility that FLAIR hyperintensity reflects blood brain barrier changes during ischemia. Future studies to validate the prognostic value of FLAIR ratio in predicting symptomatic hemorrhagic transformation are warranted.

scholarly journals Quantitative Analysis of Apoptotic Cell Death Using Proton Nuclear Magnetic Resonance Spectroscopy

Blood ◽  
1997 ◽  
Vol 89 (10) ◽  
pp. 3778-3786 ◽  
Author(s):  
Francis G. Blankenberg ◽  
Peter D. Katsikis ◽  
Richard W. Storrs ◽  
Christian Beaulieu ◽  
Daniel Spielman ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Cell Death ◽  
Magnetic Resonance ◽  
1H Nmr ◽  
Signal Intensity ◽  
Intensity Ratio ◽  
Apoptotic Cell ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Signal Intensity Ratio

Abstract Quantification of apoptotic cell death in vivo has become an important area of investigation in patients with acute lymphoblastic leukemia (ALL). We have devised a noninvasive analytical method to estimate the percentage of apoptotic lymphoblasts in doxorubicin-treated Jurkat T-cell ALL cultures, using proton nuclear magnetic resonance spectroscopy (1H NMR). We have found that the ratio of the methylene (CH2 ) resonance (at 1.3 ppm) to the methyl (CH3 ) resonance (at 0.9 ppm) signal intensity, as observed by 1H NMR, is directly proportional to the percentage of apoptotic lymphoblasts in vitro. The correlation between the CH2/CH3 signal intensity ratio and the percentage of apoptotic lymphoblasts was optimal 24 to 28 hours after doxorubicin treatment (r2 = .947, N = 27 samples). There was also a direct temporal relationship between an increase in the CH2/CH3 signal intensity ratio and the onset of apoptosis as detected by nuclear morphologic analysis, fluorescein-annexin V flow cytometry, and DNA gel electrophoresis. Thin-layer chromatography confirmed that a dynamic and/or compositional change of the plasma membrane, rather than increases in lipase activity or fatty acid production, appears to account for the increase in the CH2/CH3 signal intensity ratio during apoptosis. 1H NMR may have clinical utility for the early noninvasive assessment of chemotherapeutic efficacy in patients with ALL.

scholarly journals Apparent Diffusion Coefficient Signal Intensity Ratio Predicts the Effect of Revascularization on Ischemic Cerebral Edema

2018 ◽  
Vol 45 (3-4) ◽  
pp. 93-100 ◽  
Author(s):  
Matthew B. Bevers ◽  
Thomas W.K. Battey ◽  
Ann-Christin Ostwaldt ◽  
Reza Jahan ◽  
Jeffrey L. Saver ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Cerebral Edema ◽  
Signal Intensity ◽  
Intensity Ratio ◽  
Response To Therapy ◽  
Signal Intensity Ratio ◽  
Edema Formation ◽  
Post Stroke ◽  
Apparent Diffusion

Background: Apparent diffusion coefficient (ADC) imaging is a biomarker of cytotoxic injury that predicts edema formation and outcome after ischemic stroke. It therefore has the potential to serve as a “tissue clock” to describe the extent of ischemic injury and potentially predict response to therapy. The goal of this study was to determine the relationship between baseline ADC signal intensity, revascularization, and edema formation. Methods: We examined the ADC signal intensity ratio (ADCr) of the stroke lesion (defined as the baseline DWI hyperintense region) compared to the contralateral normal hemisphere in 65 subjects from the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy trial. The associations between ADCr, neurologic outcome, and cerebral edema were examined. Finally, we explored the interaction between baseline ADCr and vessel recanalization at day 7 on post-stroke edema. Results: We found that lower initial ADCr was associated with a worse outcome on the modified Rankin Scale (mRS) at 90 days (52.2% of those with ADCr <64% were mRS 5–6 vs. 19.1% with ADCr ≥64%, p = 0.006). Those subjects with reconstitution of flow distal to the initial vessel occlusion showed greater normalization of ADCr on follow-up scan (increase in ADCr of 16.4 ± 2.07 vs. 1.99 ± 4.33%, p = 0.0039). In those patients with low baseline ADCr, successful revascularization was associated with reduced edema (median swelling volume 164 mL [interquartile range (IQR) 53.3–190 mL] vs. 20.7 mL [IQR 3.20–55.1 mL], p = 0.024). Conclusions: This study reaffirms the association of ADCr with outcome after stroke, supports the idea that reperfusion may attenuate rather than enhance post-stroke edema, and indicates that the degree of edema with and without revascularization may be predicted by ADCr.

scholarly journals Accelerated acquisition of carotid MR angiography using 3D gradient-echo imaging with two-point Dixon

2020 ◽  
Vol 62 (10) ◽  
pp. 1345-1349
Author(s):  
Ryusuke Irie ◽  
Shiori Amemiya ◽  
Tsuyoshi Ueyama ◽  
Yuichi Suzuki ◽  
Kouhei Kamiya ◽  
...  
Keyword(s):  
Signal Intensity ◽  
Intensity Ratio ◽  
Mr Angiography ◽  
Carotid Bifurcation ◽  
Visual Assessment ◽  
Signal Intensity Ratio ◽  
Scan Time ◽  
Signal Change ◽  
Significant Difference ◽  
Gradient Echo Imaging

Abstract This pilot study tests the feasibility of rapid carotid MR angiography using the liver acquisition with volume acceleration-flex technique (LAVA MRA). Seven healthy volunteers and 21 consecutive patients suspected of carotid stenosis underwent LAVA and conventional time-of-flight (cTOF) MRAs. Artery-to-fat and artery-to-muscle signal intensity ratios were manually measured. LAVA MRA exhibited a significantly larger artery-to-fat signal intensity ratio compared with cTOF MRA in all slices (P < 0.001) and exhibited a larger (P < 0.001) or equivalent (P = 1.0) artery-to-muscle signal intensity ratio in the extracranial carotid arteries. The image quality of the cervical carotid bifurcation and the signal change on each MRA were visually assessed and compared among the MRAs. There was no significant difference between the two MRAs in visual assessment. LAVA MRA can provide visualization similar to cTOF MRA in the evaluation of the cervical carotid bifurcation while reducing scan time by one-fifth.

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