MRI system,as an imaging diagnosis equipment,plays a very important role in diagnosis and treatment.For the steady avail of MRI system,MRI eliminable faults in CBMDisc(1995~2006) were analyzed.The types and occurrence frequency of MRI eliminable faults were elaborated so as to provide reliable data for reference.

MRI system is composed of many independent subsystems, in which RF, Gradient, Coil, MRI magnet subsystem are the most important and complex subsystems. Every subsystem consists of different components. Based on the analysis of MRI eliminable faults in CBMDisc (1995 ~ 2006), the types and occurrence frequency of MRI eliminable faults are expatiated so as to provide reliable data for reference.

Based on the analysis on "China biomedical medical literature database"(CBMdisc) in the field of MRI Maintenance composed by army writers from May,1994 to 2007,the following results can be obtained: the total number of writers amounts to 75,106 person-time,27 of them are the first writers,and 11 are main writers;among the total 48 pieces of work,33 pieces are written by more then one writer;the unit with the largest number of published writers is Jinan Military Area Command with Nanjing Military Area Command the second,Lanzhou Military Area Command the third;one main writer has a maximum of 7 pieces.The research makes a close study of the army writers in field of MRI maintenance,indicating the lack of intellectual personnel in the domain of Medicine Engineering in military system.

Statistically analyses SIEMENS SIREGRAPH CF digital gastrointestinal machine the breakdown and maintenance cost which appears in the radialized practice by the note for the fault maintenance,making fault statistics by Excel,discusses in the emission practice,how displays the equipment benefit fully and saves the service cost possibly,and the results of digital gastrointetinal machine's fault frequency of system is got.to discuss the reasonality of this kind of equipment voluntarily services in second level of hospital.[Chinese Medical Equipment Journal,2008,29(2):78-79]

Technology of radiotheraphy has stepped into an era of digital photography and replaced the screen piece combination system.This thesis briefly expounds the advantages and prospect of computer X-ray photography,and discusses its problems and effective solutions in clinical practice.

Objective To assess the inter-scanner reliability and reproducibility of 3D whole-brain pseudo-continuous arterial spin labeling (pCASL) of posterior circulation territory in healthy adults.Methods Twelve healthy subjects were scanned twice on two different 3.0 T MR scanners with 3D wholebrain pCASL technique.Intervals between tests were among 10-15 days.The ASL data with two post labeling delay time (PLD) of 1.5 and 2.5 seconds were acquired during every scanning.The cerebral blood flow (CBF) values of posterior circulation territory including cerebellum,midbrain,pons,medulla oblongata,thalamus and occipital lobe were extracted based on SPM technique for comparison.The interscanner reliability and reproducibility were evaluated with the intraclass correlation coefficient (ICC) and Bland-Altman plot.Results The CBF values of posterior circulation territory were 36-47 ml · min-1 ·100 g-1 (PLD =1.5 s) and 36-46 ml · min-1 · 100 g-1 (PLD =2.5 s).Comparing the data between the two tests,the ICC was 0.851 at PLD =1.5 s and 0.914 at PLD =2.5 s.The Bland-Altman showed the reproducibility at PLD =2.5 s was better than that at PLD =1.5 s.Conclusions The 3D whole-brain pCASL technique is available for measuring the CBF at posterior circulation territory with high reliability and reproducibility especially using longer PLD.It can be used for MR multicenter study on blood flow of posterior circulation territory.

Objective To provide reference for CT performance/quality test. Methods Researches were made in Chinese documentations on CT performance/quality test issued from 1998-aug 2002.Results Approximately a quarter of CTs among the documents assembly released public were tested unqualified . Qualification rate of new CTs was higher Than second-handed ones. Part of items and data in the documentations were insufficient. Conclusion CT performance/quality test is a crucial part of system Engineering of QC(quality control),therefore it must be implemented seriously and relevant regulations should be optimized in order to benefit both patients and health-care communities.

Objective To investigate the effect of magnetic nanocomposites on proliferation ability of human hepatoma carcinoma (HCC)cells (HepG2 cell line).Methods Leucine-rich repeat-containing G protein-coupled receptor (LGR) 5-small interfering ribonucleic acid (siRNA ) was composited with polyethylenimine wrapped superparamagnetic iron oxide nanoparticle (PEI-SPIO)as the gene vector.PEI group was established by transfecting HepG2 cells when cell fusion reached 60% and SI group was established by transfecting HepG2 cells with equivalent simple LGR5-siRNA.Control (Ctrl)group was also established without transfecting.The efficiency of nanocomposites entering cells was scanned with MRI T2.The inhibition rate of cell proliferation was detected by (cell count kit,CCK)-8 assay.The expression level of messenger ribonucleic acid (mRNA)in LGR5 of cells was detected by reverse transcriptase polymerase chain reaction (RT-PCR)and the protein expressions of LGR5 and cyclin D1 were detected by western blotting.Results MRI T2 signal of HepG2 cells in PEI group decreased significantly.Compared with Ctrl group,the inhibition rate of cell proliferation of HepG2 cells in PEI group was significantly increased.The relative expression of LGR5 mRNA and the relative expression of LGR5 and cyclin D1 protein were both significantly decreased (all in P <0.05),while the corresponding indexes of the cells in SI group had no statistical significance (all in P>0.05 ).Conclusions Magnetic nanocomposites PEI-SPIO composited with LGR5-siRNA may effectively transfect HepG2 cells.Its mechanism may take effect through down-regulating the expression of cyclin D1 to inhibit the proliferation ability of hepatocellular carcinoma HepG2 cells.