Comparison of dual-source parallel radio frequency transmission liver MRI at 3.0 T with conventional MRI

AIM

Aim of the present study was to investigate the role of dual-source parallel Radio frequency (RF) and single-source excitation in liver imaging at 3.0 T MR.

METHODS

This study was a retrospective analysis. One hundred and seven subjects underwent a 3.0 T TX MR scanning including axial spectrally selective attenuated inversion recovery (SPAIR) T2WI, axial DWI and coronal balanced-fast field echo (Balanced FFE). Each sequence was carried out with both single-source and dual-source RF excitation. Student's t test was used to compare whether there was difference between single-source and dual-source RF excitation in the image uniformity, single-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Wilcoxon signed rank test was used to determine whether there was difference between conventional and parallel transmission in the score of image quality. Reader agreement was assessed using the Cohen's Kappa test.

RESULTS

For the image uniformity, there was significant difference between single-source and dual-source excitation (418.40±66.75 for single-source vs. 416.26±50.61 for dual-source, t=2.524, P<0.05). There also existed significant difference between single-source and dual-source excitation in SNR and CNR, respectively. The SNR and CNR of parallel transmission (22.03±12.16 and 18.33±10.01, respectively) were both higher than those of single transmission (20.36±11.21 and 15.22±8.95, respectively) (t=-2.630, P<0.05 for SNR and t=-4.238, P<0.05 for CNR). Image quality comparisons revealed significantly better results with dual-source than single-source RF excitation at SPAIR T2WI (1.4±0.42 vs. 1.81±0.27), DWI (1.08±0.46 vs. 1.63±0.36) and balanced FFE sequence (0.95±0.45 vs. 1.65±0.37, Z=-5.894, -5.801 and -6.985, respectively, P<0.01). In the comparison of image quality, the agreement between the two readers was very good (Kappa>0.8, P<0.05).

CONCLUSION

Dual-source parallel RF excitation MR imaging in liver enables reducing dielectric shading, improving homogeneity of the RF magnetic induction field, and increasing SNR and CNR at 3.0 T.

Involvement of T helper type 17 and regulatory T cell activity in tumour immunology of bladder carcinoma

T helper type 17 (Th17) and regulatory T cells (T(reg) ) play an important role in the pathogenesis of inflammation and autoimmune disorders. Recent studies have suggested that they also had an impact on tumour immunology. However, the relationship between Th17 and T(reg) cells in the pathogenesis of bladder carcinoma is still unclear. Flow cytometry was used to analyse the numbers, phenotype and cytokine production of Th17 cells in peripheral blood and tumour tissue from bladder carcinoma patients, in parallel with analysis of T(reg) cells. The suppressor capacity of T(reg) and the potential effects of interleukin (IL)-2 on the differentiation of Th17 and T(reg) cells in vitro were studied in a T cell stimulation and suppression assays. The results were as follows: Th17 cells were enriched in the tumours of patients with bladder carcinoma compared with the peripheral blood of patients and controls; patients with bladder carcinoma had a higher proportion of T(reg) cells in peripheral blood compared with healthy controls and nearly all patients examined showed a relative enrichment of tumour-infiltrating T(reg) with respect to peripheral blood; there appeared to be an inverse relationship between tumour-infiltrating Th17 and T(reg) cells; IL-2 could convert tumour-infiltrating T(reg) cells cultured in the presence of the autologous irradiated CD3(-) fraction into Th17 cells, down-regulate forkhead box P2 expression and suppressive capacity of T(reg) cells. This study is the first to define the frequency and characteristics of Th17 cells in bladder carcinoma. We suggest that the balance between Th17 and T(reg) cells may be involved in the development or progression of bladder carcinoma.

Use of in vivo imaging system-bioluminescence imaging to inspect tumor dynamic morphology

AIM

The aim of this study was to evaluate the veracity and sensitivity of in-vivo imaging system (IVIS) for inspection of tumor dynamic morphology.

METHODS

Mouse melanoma cells (B16-F10-luc-G5) in 100 mL media were seeded into a 96-well plate by 1:2 serial dilution from 10000 cells (well #1) to 78 cells (well #8). The plate was imaged using IVIS system to evaluate its sensitivity for luminescence. Ten Bablc mice with tumor cells were injected subcutaneously (1 x 10(5) in 100 mL) and tumor luminescence was detected by IVIS at Day 0, Day 3, Day 5, Day 7 and Day 9.

RESULTS

As few as 78 tumor cells were detectable by IVIS. A strong correlation between number of tumor cells and bioluminescence (R2=0.99) was also demonstrated. Tumor luminescence were observed in all mice by IVIS at all days, and there was significant difference (P<0.01) between each two days from Day 0 to Day 9. Moreover, tumor dynamic morphology could be monitored by IVIS when it is invisible.

CONCLUSION

Compared with conventional methods, with high veracity and sensitivity, IVIS system should be recommended as an effective method for inspection of tumor dynamic morphology.

Using bulked extremes and recessive class to map genes for photoperiod-sensitive genic male sterility in rice

Photoperiod-sensitive genic male sterile (PS-GMS) rice has a number of desirable characteristics for hybrid rice production. In this study we made use of a published rice genetic linkage map to determine the locations of PSGMS genes and we have characterized the effects of these genes on sterility by using molecular markers. A two-step approach was designed for mapping the genes: (i) identifying possible PSGMS gene-containing chromosome regions with bulked DNA from extreme fertile and extreme sterile plants of a very large F2 population and (ii) determining the map locations of the genes in extreme sterile individuals. We show that this mapping method is much more cost effective and statistically efficient than using a random sample of an F2 population. We identified two chromosomal regions each containing a PSGMS locus, one designated pms1 on chromosome 7 and one designated pms2 on chromosome 3. The existence of these two loci was confirmed by a large sample assay and with data on rationing progenies of the F2 plants. A marker-based analysis shows that the effect of pms1 is 2-3 times larger than that of pms2 and that dominance is almost complete at both loci. Implications in the breeding of PSGMS rice lines are discussed.

Genetic diversity and differentiation of indica and japonica rice detected by RFLP analysis

Genetic diversity and differentiation in indica and japonica groups of the cultivated rice (Oryza sativa L.) were studied by assaying DNA restriction fragment length polymorphisms of 12 indica and 14 japonica rice lines digested with three restriction endonucleases. A total of 49 probes were selected to represent the entire RFLP map at intervals of 20-30 cM. It was shown that 95 of the 145 possible probe/enzyme combinations, involving 43 probes and all three enzymes, detected restriction fragment length variation, and the degree of polymorphism varied greatly from one probe/enzyme combination to another. These results demonstrate that indica rice is genetically more diverse than japonica type. Significant differentiation between the two rice groups was detected by 33 probes representing 11 of the 12 rice chromosomes. It was deduced that the processes leading to differentiation involved a combination of molecular events that include base substitutions and insertion/deletions.