The feasibility of chemical exchange saturation transfer imaging of myocardial creatine metabolites:a 3.0 T MR study in phantom model / 中华放射学杂志

Objective To investigate the feasibility of chemical exchange saturation transfer (CEST) imaging in the measurement of myocardial creatine (Cr) metabolites in phantom model using 3.0 T MR. Methods Five phantoms were made according to the volume percentage of Cr ranging from 10 to 50 mmol/L with an interval of 10 mmol/L. 3.0 T MR examinations with base protocol sequence,sequence with and without ECG were performed. Signal to noise,CrEST effect and Z spectra were analyzed. Comparison of signal noise ratio (SNR) among the three methods was performed using an analysis of variance. Bivariate correlations were obtained through Pearson analysis. Results Phantom studies demonstrated that different concentrations of Cr exhibited significant CEST effect with the three sequences. The SNR obtained by sequences with and without ECG were both higher than that of base sequence (both P<0.05). Moreover,no significance of SNR was found between sequences with and without ECG (P>0.05). There were positive correlation of MTR between sequences with ECG,sequences without ECG and base protocol sequence (r2= 0.974 and 0.997, both P<0.05). Conclusion Compared with base protocol sequence, the optimized sequence with ECG can acquire higher SNR CrEST images,indicating that myocardial CrEST imaging could be performed in clinical practice.

Tumor volume of resectable gastric adenocarcinoma on multidetector computed tomography: association with N categories

OBJECTIVE: To determine whether the gross tumor volume of resectable gastric adenocarcinoma on multidetector computed tomography could predict the presence of regional lymph node metastasis and could determine N categories. MATERIALS AND METHODS: A total of 202 consecutive patients with gastric adenocarcinoma who had undergone gastrectomy 1 week after contrast-enhanced multidetector computed tomography were retrospectively identified. The gross tumor volume was evaluated on multidetector computed tomography images. Univariate and multivariate analyses were performed to determine whether the gross tumor volume could predict regional lymph node metastasis, and the Mann-Whitney U test was performed to compare the gross tumor volume among N categories. Additionally, a receiver operating characteristic analysis was performed to identify the accuracy of the gross tumor volume in differentiating N categories. RESULTS: The gross tumor volume could predict regional lymph node metastasis (p<0.0001) in the univariate analysis, and the multivariate analyses indicated that the gross tumor volume was an independent risk factor for regional lymph node metastasis (p=0.005, odds ratio=1.364). The Mann-Whitney U test showed that the gross tumor volume could distinguish N0 from the N1-N3 categories, N0-N1 from N2-N3, and N0-N2 from N3 (all p<0.0001). In the T1-T4a categories, the gross tumor volume could differentiate N0 from the N1-N3 categories (cutoff, 12.3 cm3), N0-N1 from N2-N3 (cutoff, 16.6 cm3), and N0-N2 from N3 (cutoff, 24.6 cm3). In the T4a category, the gross tumor volume could differentiate N0 from the N1-N3 categories (cutoff, 15.8 cm3), N0-N1 from N2-N3 (cutoff, 17.8 cm3), and N0-N2 from N3 (cutoff, 24 cm3). CONCLUSION: The gross tumor volume of resectable gastric adenocarcinoma on multidetector computed tomography could predict regional lymph node metastasis and N categories.

Effect of branched-chain amino acids, valine, isoleucine and leucine on the biosythesis of bitespiramycin 4"-O-acylspiramycins

Bitespiramycin, a group of 4"-O-acylated spiramycins with 4"-O-isovalerylspiramycins as the major components, was produced by recombinantspiramycin-producing strain Streptomyces spiramyceticus harboring a 4"-O-acyltransferase gene. The experiment was initially performed in synthetic medium with 0.5 g l-1 Valine, Isoleucine or Leucine feeding at 36 h cultivation. When valine was fed, the biological titer of bitespiramycin was 45.3 percent higher than that of the control group, but the relative content of total isovalerylspiramycin components decreased by 22.5 percent. In the case of ilecine, the biological titer of bitespiramycin and the total isovalerylspiramycins alone were 85 percent and 72.1 percent of the control group, respectively. In contrast, the relative content of other acylated spiramycins increased by 54.41 percent. However, leucine feeding increased the relative content of total isovalerylspiramycins by 41.9 percent while the biological titer of bitespiramycin was nearly equal to that of the control group. The improvement effect of leucine on the biosynthesis of isovalerylspiramycins was further confirmed by feeding of 2.0 g l-1 leucine to the culture with complex medium. After batch feeding with a total amount of 2.0 g l-1 leucine to the culture from 70 h to 90 h, the biological titer of bitespiramycin was almost unreduced, and the final relative content of total isovalerylspiramycins increased from 31.1 percent to 46.9 percent.