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

One of the most remarkable achievements of in vivo NMR spectroscopy has been the detection of rapid enzyme-catalyzed exchange reactions using phosphorus-31 magnetic resonance spectroscopy-based magnetization transfer experiments. In this paper, we report, for the first time, the in vivo carbon magnetization transfer (CMT) effect and in vivo detection of the CMT effects of the alpha-ketoglutarate <--> glutamate and the oxaloacetate <--> aspartate reactions, both of which are catalyzed by aspartate aminotransferase. By saturating the carbonyl carbon of alpha-ketoglutarate at 206 ppm in alpha-chloralose anesthetized adult rat brain, the unidirectional glutamate --> alpha-ketoglutarate flux was determined to be 78 +/- 9 mumol/g/min (mean +/- SD, n = 11) following i.v. infusion of [1,6-(13)C(2)]D-glucose. Contribution from aspartate aminotransferase-catalyzed partial reactions to the observed CMT effects was emphasized. Because of the large chemical shift separation between the alpha-carbons of the amino acids and the carbonyl carbons of the corresponding cognate keto acids, the spillover of the saturation radiofrequency pulses to the alpha-carbon resonances was negligible. The results indicate that the magnetization transfer effects of aspartate aminotransferase-catalyzed reactions can be used as new biomarkers accessible to non-invasive in vivo magnetic resonance spectroscopy techniques.     

Erratum to Analytical solution to the transient phase of steady state free precession sequences. Magn Reson Med 2009;62:149–164

Compressed sensing (CS) is a promising method to speed up MRI. Because most clinical MRI scanners are equipped with multichannel receive systems, integrating CS with multichannel systems may not only shorten the scan time but also provide improved image quality. However, significant computation time is required to perform CS reconstruction, whose complexity is scaled by the number of channels. In this article, we propose a reconstruction procedure that uses ubiquitously available multicore central processing unit to accelerate CS reconstruction from multiple channel data. The experimental results show that the reconstruction efficiency benefits significantly from parallelizing the CS reconstructions and pipelining multichannel data into multicore processors. In our experiments, an additional speedup factor of 1.6–2.0 was achieved using the proposed method on a quad‐core central processing unit. The proposed method provides a straightforward way to accelerate CS reconstruction with multichannel data for parallel computation. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Erratum to: Wen H et al., Magnetic resonance imaging assessment of myocardial elastic modulus and viscosity using displacement imaging and phase‐contrast velocity mapping. Magn Reson Med 2005;54:538‐548.

The original article to which this Erratum refers was published in Magnetic Resonance in Medicine (2005) 54(4) 538–548.     

Riederer SJ. The Whitaker Foundation: 25 years of support for young investigators in magnetic resonance. Magn Reson Med 2005;53:1241‐1242.

The original article to which this Erratum refers was published in Magnetic Resonance in Medicine (2005) 53(6) 1241–1242.     

Gillies RJ,et al. MRI of the tumor microenvironment. J Magn Reson Imaging 2002; 16:430–450.

The original article to which this Erratum refers was published in Journal of Magnetic Resonance Imaging (2002) 16(4) 430–450.     

Hsu J‐J and Glover GH. Mitigation of susceptibility‐induced signal loss in neuroimaging using localized shim coils,Magn Reson Med 2005;53:243‐248.

The original article to which this Erratum refers was published in Magnetic Resonance in Medicine (2005) 53(2) 243–248.