In vivo carbon-13 magnetization transfer effect. Detection of aspartate aminotransferase reaction

2005 ◽  
Vol 54 (6) ◽  
pp. 1321-1326 ◽  
Author(s):  
Jun Shen
Keyword(s):  
Aspartate Aminotransferase ◽  
Magnetization Transfer ◽  
Transfer Effect

scholarly journals Fast Isotopic Exchange between Mitochondria and Cytosol in Brain Revealed by Relayed 13C Magnetization Transfer Spectroscopy

2009 ◽  
Vol 29 (4) ◽  
pp. 661-669 ◽  
Author(s):  
Jehoon Yang ◽  
Su Xu ◽  
Jun Shen
Keyword(s):  
Isotopic Exchange ◽  
Tricarboxylic Acid Cycle ◽  
Magnetization Transfer ◽  
Tricarboxylic Acid ◽  
Transfer Effect ◽  
Resonance Spectroscopy ◽  
Exchange Reactions ◽  
Acid Cycle ◽  
Longitudinal Relaxation

In vivo13C magnetic resonance spectroscopy has been applied to studying brain metabolic processes by measuring 13C label incorporation into cytosolic pools such as glutamate and aspartate. However, the rate of exchange between mitochondrial α-ketoglutarate/oxaloacetate and cytosolic glutamate/aspartate ( Vx) extracted from metabolic modeling has been controversial. Because brain fumarase is exclusively located in the mitochondria, and mitochondrial fumarate is connected to cytosolic aspartate through a chain of fast exchange reactions, it is possible to directly measure Vx from the four-carbon side of the tricarboxylic acid cycle by magnetization transfer. In isoflurane-anesthetized adult rat brain, a relayed 13C magnetization transfer effect on cytosolic aspartate C2 at 53.2ppm was detected after extensive signal averaging with fumarate C2 at 136.1ppm irradiated using selective radiofrequency pulses. Quantitative analysis using Bloch–McConnell equations and a four-site exchange model found that VxE13–19 µmol per g per min (≫ VTCA, the tricarboxylic acid cycle rate) when the longitudinal relaxation time of malate C2 was assumed to be within ±33% of that of aspartate C2. If VxE VTCA, the isotopic exchange between mitochondria and cytosol would be too slow on the time scale of 13C longitudinal relaxation to cause a detectable magnetization transfer effect.

Contrast-Enhanced MRI with Magnetization Transfer Effect in the Imaging of Brain Metastatic Lesions

2017 ◽  
pp. 8-17
Author(s):  
A. A. Ermakova ◽  
O. Yu. Borodin ◽  
M. Yu. Sannikov ◽  
S. D. Koval ◽  
V. Yu. Usov
Keyword(s):  
Comparative Analysis ◽  
Roc Analysis ◽  
Magnetization Transfer ◽  
Metastatic Lesion ◽  
Transfer Effect ◽  
Wilcoxon Test ◽  
Post Contrast ◽  
Metastatic Lesions ◽  
The Brain ◽  
Non Parametric

Purpose: to investigate the diagnostic opportunities of contrast  magnetic resonance imaging with the effect of magnetization transfer effect in the diagnosis of focal metastatic lesions in the brain.Materials and methods.Images of contrast MRI of the brain of 16  patients (mean age 49 ± 18.5 years) were analysed. Diagnosis of  the direction is focal brain lesion. All MRI studies were carried out  using the Toshiba Titan Octave with magnetic field of 1.5 T. The  contrast agent is “Magnevist” at concentration of 0.2 ml/kg was  used. After contrasting process two T1-weighted studies were  performed: without T1-SE magnetization transfer with parameters of pulse: TR = 540 ms, TE = 12 ms, DFOV = 24 sm, MX = 320 × 224  and with magnetization transfer – T1-SE-MTC with parameters of pulse: ΔF = −210 Hz, FA(МТС) = 600°, TR = 700 ms, TE = 10 ms,  DFOV = 23.9 sm, MX = 320 x 224. For each detected metastatic  lesion, a contrast-to-brain ratio (CBR) was calculated. Comparative  analysis of CBR values was carried out using a non-parametric  Wilcoxon test at a significance level p < 0.05. To evaluate the  sensitivity and specificity of the techniques in the detection of  metastatic foci (T1-SE and T1-SE-MTC), ROC analysis was used. The sample is divided into groups: 1 group is foci ≤5 mm in size, 2  group is foci from 6 to 10 mm, and 3 group is foci >10 mm. Results.Comparative analysis of CBR using non-parametric Wilcoxon test showed that the values of the CBR on T1-weighted  images with magnetization transfer are significantly higher (p  <0.001) that on T1-weighted images without magnetization transfer. According to the results of the ROC analysis, sensitivity in detecting  metastases (n = 90) in the brain on T1-SE-MTC and T1-SE was  91.7% and 81.6%, specificity was 100% and 97.6%, respectively.  The accuracy of the T1-SE-MTC is 10% higher in comparison with  the technique without magnetization transfer. Significant differences (p < 0.01) between the size of the foci detected in post-contrast T1- weighted images with magnetization transfer and in post-contrast  T1-weighted images without magnetization transfer, in particular for  foci ≤5 mm in size, were found. Conclusions1. Comparative analysis of CBR showed significant (p < 0.001)  increase of contrast between metastatic lesion and white matter on  T1-SE-MTC in comparison with T1-SE.2. The sensitivity, specificity and accuracy of the magnetization transfer program (T1-SE-MTC) in detecting foci of  metastatic lesions in the brain is significantly higher (p < 0.01), relative to T1-SE.3. The T1-SE-MTC program allows detecting more foci in comparison with T1-SE, in particular foci of ≤5 mm (96% and 86%, respectively, with p < 0.05).

scholarly journals Evaluation of Parotid Gland Function using Equivalent Cross-relaxation Rate Imaging Applied Magnetization Transfer Effect

2012 ◽  
Vol 53 (1) ◽  
pp. 138-144 ◽  
Author(s):  
Hidetoshi SHIMIZU ◽  
Shigeru MATSUSHIMA ◽  
Yasutomi KINOSADA ◽  
Hiroki MIYAMURA ◽  
Natsuo TOMITA ◽  
...  
Keyword(s):  
Parotid Gland ◽  
Relaxation Rate ◽  
Magnetization Transfer ◽  
Transfer Effect ◽  
Cross Relaxation ◽  
Gland Function

scholarly journals Multiparametric MRI detects longitudinal evolution of folic acid-induced nephropathy in mice

2018 ◽  
Vol 315 (5) ◽  
pp. F1252-F1260 ◽  
Author(s):  
Kai Jiang ◽  
Tristan A. Ponzo ◽  
Hui Tang ◽  
Prasanna K. Mishra ◽  
Slobodan I. Macura ◽  
...  
Keyword(s):  
Folic Acid ◽  
Interstitial Fibrosis ◽  
Magnetization Transfer ◽  
Kidney Injury ◽  
Multiparametric Mri ◽  
Magnetization Transfer Ratio ◽  
Kidney Volume ◽  
Kidney Size ◽  
Functional Changes

The rodent model of folic acid (FA)-induced acute kidney injury (AKI) provides a useful model for studying human AKI, but little is known about longitudinal changes in renal hemodynamics and evolution of renal fibrosis in vivo. In this work, we aimed to longitudinally assess renal structural and functional changes using multiparametric magnetic resonance imaging (MRI). Ten adult mice were injected with FA, after which a multiparametric MRI was used to measure kidney volume, hypoxia index R2*, magnetization transfer ratio (MTR), perfusion, T1, and glomerular filtration rate (GFR) at 2 wk posttreatment. Then five mice were euthanized for histology, and the other five underwent MRI again at 4 wk, followed by histology. Control mice ( n = 5) were injected with vehicle and studied with MRI at 2 wk. Trichrome and hematoxylin-eosin staining were performed to assess FA-induced tissue injuries. Whereas kidney size and oxygenation showed progressive deterioration, a transient impairment in renal perfusion and normalized GFR slightly improved by 4 wk. Kidney fluid content, as reflected by T1, was prominent at 2 wk and tended to regress at 4 wk, consistent with observed tubular dilation. Trichrome staining revealed patchy necrosis and mild interstitial fibrosis at 2 wk, which exacerbated at 4 wk. MTR detected increased fibrosis at 4 wk. In conclusion, multiparametric MRI captured the longitudinal progression in kidney damage evolving within the first month after treatment with folic acid and may provide a useful tool for assessment of therapeutic strategies.

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