Objective To explore the theory and method of 4-dimensional (4D) imaging based on a spiral CT scanner. Methods The experiments were carried out on a Toshiba Asteion TSX-021A scanner with a motion phantom which consisted of a platform and some tumor-like plastic balls driven by a step-motor in sine mode to simulate respiration. The gantry rotation cycle, pitch and slice thickness were 1.5 s, 0.6 and 3 mm,respectively,according to radiotherapeutic application. Data processing including 3D image reformation and phantom centroid tracing were accomplished on a treatment planning system TOPLANE WiMRT V1.0. Results The phantom experiments demonstrated that the quality of a reformatted 3D image was better than that of a conventional reconstructed 3D image apparently for its less motion artifacts, and the measured centroid locus of the balls based on 4D imaging was closed to the actual motion process. Conclusion 4D imaging based on a single-slice spiral CT scanner is feasible.

Objective To explore a quality assurance testing method for gemstone spectral imaging (GSI)computed tomography. Methods A phantom prototype made of 9 bottles of pure water mixed with Iopamidol (300 mg I/mL)at different Iodine concentra-tions was scanned using the GSI mode under a routine head protocol on a GE Discovery CT750 HD scanner.Then the images were post-processed on a GE AW4.6 workstation.Results Based on the effective atomic number histogram,water & Iodine scatterplot and spectral HU curve,the Iodine solution concentrations of the phantom were not only differentiated but quantified.Conclusion It is feasible to test the material decomposition capability of GSI with the phantom prototype.

Objective The histological features of chronic hepatitis B virus (HBV) infection with persistently normal serum transaminases has not been will studied. The aim of this study was to investigate clinical significance of liver biopsy for these patients. Methods A total of 452 HBsAg positive patients and clinical course of more than six months undergone percutaneous liver biopsy. All liver biopsy specimens were assessed by experienced liver pathologists blinded to the liver biochemistry and scored according to standard criteria. Results None of patients had normal liver pathology. Patients with elevated serum transaminases had significant higher degree of hepatic necrosis inflammation grade (G) and fibrosis stage (S) compared with pateitns with normal transaminase ( P

Objective To investigate the changes of NGF mRNA expression and the effect of exogenous interleukin 1?(IL 1?) on it in rats after traumatic brain injury(TBI) and to explore the mechanism of NGF and IL 1? in TBI. Methods A brain trauma model of fluid percussion in rats was established. Changes of NGF mRNA expression and effect of exogenous IL 1? on it were observed by RT PCR, molecular hybridization and immunocytochemical techniques. Results NGF mRNA expression in the brain injury site and tissues adjacent to it began to increase at 12 h after trauma and increased markedly at 24 h and reached the peak value on the 3rd. Then it decreased gradually, but still higher than that of the control. NGF mRNA expression increased at 3 h after trauma in IL 1? treatment group and was significantly higher than that in simple trauma and control groups( P

Objective To investigate the influence of physiological motions on three-dimensional (3D) CT images and the rules of motion artifacts.Methods A mathematical model of motion artifact was set up based on the principle of spiral scanning, hereby the geometrical distortion of 3D image was analyzed.Experiments were carried out with home-made phantoms on a CT scanner.Results The details of 3D images with trivial distortion were legible under static condition.On the contrary, distinct distortion occured under moving condition, and its degree increased with the pitch and motion period. The 3D images were varied with difference of the motion initial phases.Conclusion The distortion of 3D-CT image depends on the motion characters of scanned objects and scanning parameters such as pitch and slice thickness.

ObjectiveTo evaluate the diagnostic value of ultrasound or CT guided percutaneous Trucut needle biopsy on the diagnosis of pancreatic tumors.Methods One hundred and twenty-four patients clinically diagnosed as pancreatic cancer without pathological diagnosis underwent percutaneous pancreatic biopsy by using Trucut needle under ultrasound or CT guidance.ResultsOne hundred and nine procedures of ultrasound-guided biopsy and 15 procedures of CT-guided biopsy were performed,and one patient received 2.3times of punctures.Tissue samples were obtained in all 124 patients,the diagnostic accuracy was 95.2％,among them 115 were adenocarcinoma,5 were cystadenoma,2 were metastasis cancer,1 was cancer of unknown origin and 1 was normal.The sensitivity,specificity,and accuracy were 99.2％ 100％,and 99.2％,respectively.Transient serum amylase increase was observed in 3 patients; 5 patients' abdominal pain aggravated,but all recovered with conservative management.One patient was found to have tumor seeding on the spot of insertion after 34 days.No other major complications occurred.ConclusionsUltrasound or CTguided percutaneous pancreatic 16 ～ 18G Trucut needle biopsy is a safe and simple procedure with excellent diagnostic value for pancreatic cancer.

Circulating tumor DNA (ctDNA) detection is one of "liquid biopsy"analysis. It has shown promising clinical application in cancer precise medicine due to its noninvasive sampling and real-time observation. Nowadays, ctDNA analysis has been clinically validated and successfully applied in advanced cancer, including selecting personalized treatment, monitoring treatment responses, minimal residual disease and recurrence. Although there has been rapidly increasing interests in ctDNA, its clinical application in cancer precise medicine is still facing few challenges, especially in screening and diagnosing cancer at early stages. Here, the latest progress in the applications and challenges of ctDNA in advancedstage tumor therapy were reviewed to provide references for future studies on ctDNA.

Prediction of RNA secondary structures including pseudoknots is a difficult topic in RNA field. Current predicting methods usually have relatively low accuracy and high complexity. Considering that the stacking of adjacent base pairs is a common feature of RNA secondary structure, here we present a method for predicting pseudoknots based on covariance with stacking and minimum free energy. A new score scheme, which combined stacked covariance with free energy, was used to assess the evaluation of base pair in our method. Based on this score scheme, we utilized an iterative procedure to compute the optimized RNA secondary structure with minimum score approximately. In each interaction, helix of high covariance and low free energy was selected until the sequences didn't form helix, so two crossing helixes which were selected from different iterations could form a pseudoknot. We test our method on data sets of ClustalW alignments and structural alignments downloaded from RNA databases. Experimental results show that our method can correctly predict the major portion of pseudoknots. Our method has both higher average sensitivity and specificity than the reference algorithms, and performs much better for structural alignments than for ClustalW alignments. Finally, we discuss the influence on the performance by the factor of covariance weight, and conclude that the best performance is achieved when lambda1 : lambda2 = 5 : 1.
Algorithms ; Base Pairing ; Base Sequence ; Computational Biology ; methods ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA ; chemistry ; genetics ; Sequence Analysis, RNA

Objective To observe the adverse reaction, tumor response and short term outcomes of percutaneous cryoablation for locally advanced pancreatic cancer, and investigate its feasibility. Methods Fifty-nine consecutive patients with locally advanced, unresectable pancreatic cancer underwent percutaneous cryoablation at our hospital from Sept. 2008 to Sept. 2009, were prospectively studied. Percutaneous cryoablation was performed with an argon/helium-based cryosurgical system under the guidance of ultrasound.Freezing probe was inserted into the center of pancreatic mass and two cycles of freezing were performed with each cycle for 5 min and temperature at-160℃, then the temperature was returned to normal for 10 min.Serum amylase was detected before operation and 1 to 7 days postoperatively. CT or PET-CT scanning was performed for evaluation of tumor response every 4 to 6 weeks after cryoablation. Survival was assessed by Kaplan-Meier method. Results 59 patients had a total of 76 biopsy-proven tumors, which were located at the pancreas head (n = 56), body (n = 7), and tail (n = 13). The median size of tumor was 4.5 cm (range 3 ～6 cm). Nineteen patients had liver metastases. Postoperative abdominal pain occurred in 45 cases (76.3%),fever occurred in 29 cases (49.2%) and elevation of serum amylase occurred in 34 cases (57.6%). Severe complications including intra-abdominal bleeding, pancreatic leaks, ileus, and metastasis by probe tract occurred in 5 cases (8.5%). There was no death associated with cryoablation. The median hospital stay was 21 days. 2 patients (3.4%) achieved complete response, 23 patients (39.0%) achieved partial response,30patients (50.8%) had stable disease, 4 patients(6.8%) had progressive disease. The median survival was 8.4 months. The overall survival at 3, 6 and 12 months was 89.7%, 61.1% and 34.5%, respectively.Conclusions Ultrasound-guided percutaneous cryoablation appears to be a safe and feasible, minimally invasive technique for locally advanced pancreatic cancer.

Objective To study the relationship among the genome mutation,viral protein structures and virus evolution of human Bocavirus 2(HBoV2).Methods A method of PCR was applied to detect HBoV2 genome in 205 fecal specimens collected from children who had diarrhea in Ruian region,Zhejiang province,China.HBoV2-positive specimens were chosen to further amplify the HBoV2 genome.All the tertiary structures were predicted using the Swiss-PdbViewer software,and a phylogenetic analysis was performed by the MEGA software (version 5.1).Result The positive rate of HBoV2 PCR detection in the collected 205 fecal specimens was 5.36％ (11/205).We obtained a sequence of a nearly full-length HBoV2 genome named as Ruian isolate,which is 5196 bases in length.Alignment of the Ruian HBoV2 sequence with other HBoV2 sequences in GenBank revealed that the new HBoV2 shared 99.79％ similarities with the reference genome (GenBank no NC_012042).No mutation was found in the NP1 gene,whereas sense mutation of NS1,VP1 and VP2 gene were found.Residue solvent accessibilities that relates to hydrophobic interactions were changed between the NS1 of the Ruian isolate and the reference isolate.The protein structure and location of H-bonds were different between the NS1 of the Ruian isolate and the reference isolate.The phylogenetic tree shows a clear division of the NS1,which has a potential evolution toward or a closely evolutionary relationship with the NS1 of HBoV4.Conclusion HBoV2 infection was detected in Ruian region,Zhejiang province.We found sense mutations in the HBoV2 genome of Ruian isolate.These mutations may alter HBoV2 protein structures,and may have an evolutionary significance.These findings provide data of HBoV2 genome mutation.