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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