Objective To establish a method for quantitative analysis of tiny amounts of tritium in hydrogen below the detection limit of isotope ratio mass spectrometer. Methods Hydrogen was oxidized to produce water in a self-developed catalytic oxidation device filled with platinum hydrophobic catalyst. The effects of different experimental conditions on hydrogen conversion rate were investigated. The tritium concentration in the synthetic water was measured using a liquid scintillation counter. The tritium concentration in hydrogen was calculated according to the measurement of the synthetic water. Results When the flow rate of hydrogen was fixed, the conversion rate of hydrogen increased with the increase of the reaction temperature but increased and then decreased with the increase of the flow rate of oxygen. Hydrogen could be completely converted under optimal experimental conditions. The hydrogen samples with volumetric tritium concentrations in the range of 1 × 10⁻⁷ to 2 × 10⁻¹⁴ were converted to water at the reaction temperature of 110 ℃ and hydrogen/oxygen flow rate of 100 mL/min. The resulting water was measured using a liquid scintillation counter. The measurement accuracy was better than 2%. Conclusion This method can be used to measure hydrogen samples with tiny amounts of tritium below the detection limit of isotope ratio mass spectrometer. Our results provide data support for the calculation of the separation capacity of cryogenic distillation process.

Objective: To establish a TaqMan-MGB probe-based real-time fluorescence RT-PCR assay for avian influenza H5N6 virus used in rapid diagnosis for suspected cases and surveillance for outer environment of live poultry markets. Methods: Based on the conservative sequences of avian influenza H5N6 virus for HA and NA gene published on GenBank, specific primers and TaqMan-MGB probes were designed to develop and optimize for the dual real-time RT-PCR assay. Specificity, sensitivity, repeatability and comparison tests were carried out. Results: This dual real-time RT-PCR detection can be completed within 80 minutes. There was no cross-reaction with other subtypes of influenza virus and common respiratory pathogens. The minimum detection limit could be up to 10 copies/reaction. The correlation coefficient of standard curve for the gene of H5 and N6 were 0.999 and 0.993, and the coefficients of variation for cycle threshold were range from 0.151%-0.549%and 0.213%-0.575%, respectively. The positive and negative coincidence rates of the validation test were 100%. Conclusions This TaqMan-MGB probe-based dual real-time RT-PCR for avian influenza H5N6 virus was rapid, specific and sensitive. It will have a good use in early emergency detection of suspected cases and continuous monitoring of external environment in live poultry trade market.

Objective To compare the image quality of diffusion-weighted MR neurography (DW-MRN) of the tibial nerve and the common peroneal nerve prospectively using different motion probing gradients (MPGs).Methods A total of 21 healthy volunteers underwent DW-MRN at the knee (unilateral imaging) on a 3.0 T magnetic resonance system with unidirectional MPGs.The protocol included anteriorposterior unidirectional,right-left unidirectional,three-directional and six-directional MPGs.The apparent SNR and CNR of tibial nerve and common peroneal nerve were calculated.Three-dimensional MIP images of the nerves were evaluated blindly by two radiologists using a four-point grading scale on basis of entirety depiction and the signal intensity.Significance was determined by using Friedman and paired Wilcoxon tests.Results The SNR of tibial nerves on DW-MRN with anterior-posterior,right-left,three directional and six directional MPGs were 4.17 (2.70-5.65),4.35 (0.47-4.69),3.46 (2.27-4.62) and 3.30 (2.06-4.43),respectively.CNR were 0.61 (0.46-0.70),0.63 (0.36-0.73),0.55 (0.39-0.64) and 0.53(0.35-0.63),respectively.The scores of tibial nerve image quality were 4.0 (2.0-4.0),4.0 (3.0-4.0),2.5 (2.0-3.5),2.0 (1.0-2.5),respectively.Interobserver agreement was good and the Kappa value was 0.69 (P ＜ 0.05).The SNR of the common peroneal nerves on DW-MRN with anteriorposterior,right-left,three directional and six directional MPGs were 3.05 (2.30-4.20),3.05 (2.26-4.34),2.72 (1.84-13.80) and 2.68 (1.87-3.67),respectively.CNR were 0.51 (0.39-0.62),0.51 (0.39-0.63),0.46(0.30-0.86) and 0.46(0.30-0.57),respectively.The scores of the common peroneal nerve image quality were 3.5 (2.0-4.0),4.0 (2.0-4.0),2.0 (1.0-3.0) and 2.0 (1.0-2.5),respectively.Interobserver agreement was good and the Kappa value was 0.70(P ＜0.05).For SNR,CNR and nerve image quality of the tibial nerves and the common peroneal nerves,there were significant differences among different MPGs (x2 =215.01,215.01,60.49 and 182.82,182.82,60.22,respectively,P ＜ 0.05).SNR,CNR and nerve image quality of the tibial nerves and the common peroneal nerves on DW-MRN with unidirectional MPGs were better than those with three-directional and sixdirectional MPGs (Z =-6.90-4.03,P ＜ 0.05).The SNR and CNR of the tibial nerves on DW-MRN with right-left direction were better than those with anterior-posterior unidirectional MPGs (Z =-3.53,-3.41,P ＜ 0.05),but there was no significant difference of image quality between right-left and anteriorposterior directional MPGs (Z =-0.58,P ＞ 0.05).DW-MRN of the tibial nerves with three-directional MPGs was better than that with six-directional MPGs (Z =-3.00,-2.80,-3.92,P ＜ 0.05).There were no significant differences between right-left and anterior-posterior unidirectional MPGs,or between three-directional and six-directional MPGs of common peroneal nerves (Z =-1.94--0.31,P ＞ 0.05).Conclusions DW-MRN has capability to provide three-dimensional visualization of the tibial and common peroneal nerves,and the image quality with unidirectional MPGs is better than that with three or six directional MPGs.

Objective To evaluate the application of prospective ECG-gated dual source CT (DSCT) in patients with acute chest pain, and compare it's image quality and radiation dose with those of retrospective ECG-gated spiral scan. Methods Thirty consecutive patients (Group A, average HR ≥85 bpm) with acute chest pain were scanned with prospective ECG-gated scan and another 30 consecutive patients (Group B, average HR ≥85 bpm)were analyzed by retrospective ECG-gated scan. Tube voltage and tube current were adapted by the BMI of patients. MPR, MIP, CPR and VR were used to display pulmonary arteries (PA), thoracic aorta and coronary arteries (CA). Image quality as well as radiation dose were assessed in 2 groups. Qualitative image quality was compared with chi-square test between the two groups,while quantitative image quality [the image noise ( IN ), signal-to-noise ratio ( SNR ) and contrast-to-noise ratio(CNR)] and radiation dose were evaluated with x2 test and Student's t test. Results The proportion of valid coronary segments for diagnosis were 379/385 ( 98. 44% ) and 390/396 ( 98.48% ) respectively in Group A and Group B with no significant difference(x2 =0. 002,P =0. 961 ). The IN [( 16. 23 ±5.75)vs ( 16. 31 ±3. 32) HU] ,SNR (26. 85 ±9. 94 vs 24. 78 ±9. 91 ) and CNR (20. 99 ±9. 31 vs 18. 65 ±8. 72)showed no significant differences between 2 groups ( t = 0. 069,0. 908 and 1. 224, P ＞ 0. 05, respectively).The ED was on average ( 8. 37 ± 2. 69 ) mSv in Group A, whereas on average ( 20. 05 ± 5.52 ) mSv in Group B. There was a statistical difference between 2 groups ( t = 9. 401, P = 0. 000). Conclusion Low dose prospective ECG-gated DSCT angiography can show similar image quality as retrospective ECG-gated spiral scan with radiation dose.

Objective To explore the clinical value of dual-energy CT angiography (DE-CTA) in the diagnosis of carotid cavernous fistula. Methods Fourteen patients suspected of carotid cavernous fistula underwent DE-CTA between Dec. 2008 and Feb. 2010. Image post-processing of DE-CTA was performed with the dedicated software to obtain bone-removal and non bone-removal images. Four experienced radiologists evaluated image quality of DE-CTA, the number, location and size of fistulae and dilation of cerebral veins. The bone-removal and non bone-removal images were compared for displaying of fistulae and other related lesions. Kappa test was used to test the consistency of image quality evaluation between two radiologists. The sizes of fistulae were measured with bone-removal DE-CTA images and non bone-removal DE-CTA images respectively and their results were compared by using student's t-test and the correlation test. Results Twenty-eight intracranial internal carotid arteries of 14 patients showed acceptable image quality. Fourteen cases were diagnosed as carotid cavernous fistula with both bone-removal and non boneremoval DE-CTA images. Two patients presented with bilateral lesions, while 7 patients presented with left lesions and 5 patients had right lesions. Totally, sixteen fistulae lesions were detected in 14 patients. The mean size of fistulae was (0. 36 ±0. 10) mm by bone-removal images, whereas (0. 35 ±0. 11 ) mm by non bone-removal images. There was no significant difference between the two methods ( t = 0. 29, P ＞ 0. 05 ),and good correlation was found between the two methods ( r = 0. 97, P ＜0.05). Thirteen dilated cerebral veins in 8 cases were found by bone-removal images versus 9 dilated cerebral veins in 6 cases by non boneremoval images. Conclusions Image post-processing of DE-CTA is a simple and useful method to identify carotid cavernous fistula. DE-CTA is also useful for therapeutic planning.

Objective To evaluate the feasibility, accuracy and its clinical value of MRI-guided needle biopsy of lung lesions. Methods A total of 137 patients with pulmonary nodules or masses underwent lung biopsy in low-field open MRI equipped with iPath 200 optical tracking systems. Among them, 103 cases had solitary pulmonary lesion; the other 34 cases had multiple foci. The maximum diameter of the lesion was not smaller than 3.5 cm ( ≥ 3.5 cm) in 57 patients, between 1.5 cm and 3.4 cm( 1.5-3.4 cm) in 71 patients, not greater than 1.4 cm ( ≤ 1.4 cm) in 9 patients. Results The puncture success rate was 100.0% (57/57) for lesions ≥3.5 cm, 98.6% (70/71) for lesions 1.5-3.4 cm,77.8% (7/9) for lesions ≤1.4 cm and 97. 8% (134/137) for total cases, respectively. According to the pathological results, pulmonary lesions were malignant in 98 cases and benign in 39 cases. The sensitivity,specificity, accuracy, positive predictive value and negative predictive value of MRI-guided lung biopsy were 94.2%(98/104), 100.0% (33/33), 95.6% (131/137), 100.0% (98/98) and 84.6% (33/39),respectively. Conclusion MRI-guided needle biopsy of lung lesion can be performed precisely in a lowfield open MRI with a low risk of complications. As a supplement to US or CT-guided biopsy, it is worth further promotion and application.

Objective To explore the value of MR imaging-guided percutaneous lumbar discectomy and discolysis with oxygen-ozone mixture for treatment of posterolateral lumbar disc herniation via a new puncture approach of facet joint medial route. Methods All 114 lumbar intervertebral discs in 103 patients were diagnosed as posterolateral lumber disc herniation by CT or MRI, which were located at the levels of L3-4 in 5 cases, LA-5 in 87 cases and L5-S1 in 22 cases. The procedure was guided under 0. 23 T open magnetic resonance with iPath 200 optical tracking system. A 14 G MR-compatible needle was punctured into the disc center via a new puncture approach of facet joint medial route. The therapy steps were as follows: firstly, cut nucleus pulposus and inject 6 ml oxygen-ozone mixture of 60 μg/ml in the disc center;secondly, retreat the needle to the local prominence, cut prominent part and inject 6 ml oxygen-ozone mixture of 60 μg/ml. Thirdly, retreat the needle to the periradicular nerve root, inject 15 ml oxygen-ozone mixture of 40 μg/ml and 4 ml pain-block liquid. All patients were followed up at 3 days, 1 month, 3 months and 6 months after operation, evaluated for the effect of treatment with the modified Macnab criteria, and the results were compared with the χ2 test. Results All procedures were successfully performed. Intraoperative dural injury occurred in 5 cases. Postoperative infection of intervertebral space occurred in 2 cases. The clinical effective rate was 96. 1% (99/103), 84.5% (87/103), 94.2% (97/103), 95.1% (98/103)respectively at 3 days, 1 month, 3 months and 6 months after operation, and the differences were signifieant (χ2 = 12. 942, P = 0. 005 ) . Conclusion MR imaging-guided percutaneous lumbar discectomy and discolysis with oxygen-ozone mixture via facet joint medial route is a minimally invasive, safety and effective method for the treatment of posterolateral lumbar disc herniation.

Objective To investigate the usefulness of 3 T MRI 3D-FIESTA in the evaluation of the intraparotid components of the facial nerve and parotid duct, and compare them with surgical findings. Methods Twenty-two cases with parotid benign tumors were scanned with conventional and 3D-FIESTA sequences on 3 T MRI scanner. Postprocessed multiplanar images were obtained with the workstation. Parotid ducts and facial nerves and tumors were identified on these images. The relationship of the tumors to the facial nerves and Parotid ducts was confirmed at surgery. Results Various types of parotid benign tumors had their characteristics on 3 T MR imaging. Parotid benign tumors mainly showed hypo-intensity on T_1WI in 21 cases, and hyper-intensity on T_2WI in 22 cases. But on 3D-FIESTA images, they appeared hypo-intensity (10 cases) or high intensity (12 cases) due to different types. Facial nerves in parotid appeared as linear structures with hypo-inteusity. The indication of the main trunks were 16 and 18 cases for T_1WI and T_2WI images, while on 3D-FIESTA images, the main trunks and cervicofacial and temporofacial divisions of the facial nerves were found in 22, 21,22 cases. Parotid ducts appeared as structures with hypo-intensity on T_1WI and hyper-intensity on multiplanar images (14, 20, 22 cases). Compared with surgical results, the main trunks of the facial nerve were correctly showed by 3D-FIESTA images in 20 cases. However, in 2 cases they were not located in the operation because of shifting. Conclusion 3 T MR 3D-FIESTA imaging could depict the extracranial facial nerve and the parotid duct in the parotid gland, which is useful for preoperative evaluation of parotid gland tumors.

Objective To explore the value of MR imaging-guided percutaneous cervical discectomy and discolysis with oxygen-ozone mixture for treatment of cervical disc herniation.Methods Eight herniated cervical discs in 7 patients were diagnosed by MRI, including 5 discs of lateral protruding type, 2 discs of paramedian protruding type and one disc of central protruding type.All patients underwent MR imaging-guided percutaneous cervical discectomy and discolysis with oxygen-ozone mixture.The procedures were guided by a set of 0.23 T open MR system mounted with iPath 200 optical tracking system.The herniated portion of the disc was punctured with a 14 G MR-compatible needle in the healthy side via anterolateral oblique route.The interventional steps were as follows; firstly, cut herniated part with percutaneous discectomy probe and inject 2ml oxygen-ozone mixture of 60 μg/ml; secondly, retreat the needle to the disc center, resect nucleus pulposus, and inject 2 ml oxygen-ozone mixture of 60 μg/ml.All patients were followed up for 6 months, with 4 patients by telephone and 3 patients in outpatient clinic.The effect of treatment was evaluated according to Williams postoperative assessment standard.Results All procedures were performed successfully.The clinical outcome was evaluated as excellent in 5 cases, good in 1 case and fair in 1 case.The total ratio of excellent and good was 85.7%.No serious complication occurred expect 1 case with intraoperative paroxysmal pain.Conclusion MR imaging-guided percutaneous cervical discectomy and discolysis with oxygen-ozone mixture was a safe, effective and minimally invasive method for the treatment of cervical disc herniation.

Objective To explore convenient and practical semi-quantitative MRS indicators in diagnosis of prostate cancer.Methods One hundred patients with completer MRS data and clinical data were enrolled in the study.The following parameters were assessed to evaluate their efficacy in diagnosis of prostate cancer, (Cho + Cr)/Cit of single voxel, mean (Cho + Cr)/Cit of the whole area and (Cho + Cr)/ Cit positive voxel ratio at the sextant level.Similarly, all the parameters mentioned above and mean (Cho +Cr)/Cit positive voxel ratios of the whole gland were assessed at the whole gland level.Pearson test and Kappa test were used in the research.Results Two thousand nine hundred and forty-five voxels were assessed including 1203 in cancer positive region and 1742 in cancer negative regioa The range of the (Cho + Cr) /Cit ratio in cancer positive region was from 0.22 to 8.00 (median, 1.87), and that in cancer negative region was from 0.11 to 8.00 (median, 0.53).The (Cho + Cr)/Cit ratio in cancer positive region was higher than that in cancer negative region (Z =28.48, P<0.01) with partial overlap.On the level of sextant, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of (Cho + Cr)/Cit ratio> 0.911 to diagnose prostate cancer were 81.4% (179/220),64.2% (194/302), 62.4% (179/287) 、82.6% (194/235) 、71.5% (373/522) respectively; those of mean (Cho + Cr)/Cit ratio>0.911 were 77.3% (170/220),77.2% (233/302),71.1% (170/239),82.3% (233/283),77.2% (403/522) respectively; those of positive voxel ratio>0.519 were 73.2% (161/220),80.8% (244/302)、 73.5% (161/219),80.8% (244/302), 77.6% (405/522) respectively; the consistency between mean (Cho + Cr) /Cit ratio and positive voxel ratio was high (Kappa=0.907).On the level of the whole prostate, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of (Cho + Cr)/ Cit ratio>0.911 to diagnose prostate cancer were 94.3% (50/53),40.4% (19/47),64.1% (50/78), 86.4% (19/22),69.0% (69/100) respectively; those of mean (Cho + Cr)/Cit ratio>0.911 were73.6% (39/53),83.0% (39/47), 83.0% (39/47), 73.6% (39/53), 78.0% (78/100) respectively; those of maximum positive voxel ratio> 0.519 were 88.7% (47/53),61.7% (29/47),72.3% (47/65),82.9% (29/35),76.0% (76/100) respectively; those of mean positive voxel ratio>0.519 were 62.3% (33/53), 85.1% (40/47), 82.5% (33/40), 66.7% (40/60), 73.0% (73/100) respectively; the consistency between mean (Cho + Cr)/Cit ratio and mean positive voxel ratio was fairly high (Kappa =0.818).Conclusion Single voxel criteria were suggested to diagnose clinically suspected prostate cancer.Maximum positive voxel ratio criteria were suggested to guide localization in biopsy.