Objective To observe the surface morphology of dentin irradiated by Er,Cr∶YSGG laser under anhydrous conditions and discuss the possible clinical applications of the laser.Methods 11 freshly extracted specimens (approximately 1.5 mm thick) taken from the first premolars were selected.One was regarded as the control group without any treatment and the remaining ten were divided into 5 groups whose dentin surface was irradiated by Er,Cr∶ YSGG laser with different energy (1,2,3,4,6 W) under anhydrous condition.The specimens were routinely prepared for electron microscopic scanning observation.Results As the output power increased with Er,Cr∶YSGG laser irradiation,the dentin surface was observed of the constriction of tubular lumen,and part of the tubules closed.The dentin surfaces with 3 ～6 W laser irradiation were observed thermal injury alters such as micro crack and carbonization.Conclusion 1 ～2 W anhydrous Er,Cr:YSGG laser irradiation play a more ideal and safe constriction and sealing role to dentinal tubules,and the laser is expected to be used for the treatment of dentin hypersensitivity.

Objective To evaluate the usefulness of extrapleural locating method in CT-guidod transthoracic pulmonary biopsy to prevent or reduce the size of peumothorax.Methods One hundred and fifteen cases of CT-gnided transthoracic pulmonary biopsy with the pulmonary lesions not in direct contact with the pleura were selected.Of 115 cases,46 were performed with extrapleural locating method (EPL) and 69 cases with lesion edge locating method (LEL).Taking the maximum distance between the partial and visceral pleura (MPVD) measured on the CT image after the procedure as the index of the volume of pneumothorax.The incidence and volume of pneumothorax of both groups were compared and statistically analysed with R ×C Chi-Square test.The retention time of the biopsy needle in the lung parenchyma of the two group was documented and the average time was calculated in each group.Results The incidence of pneumothorax was 45.7% (21/46),median 0.4 cm with EPL group,and 66.7% (46/69) and median 0.3cm with LEL group.When the distance between the lesion and pleura was equal or smaller than 2 cm (≤2cm),the incidence of pneumothorax was 39.4% (13/33) with EPL group and 73.2% (30/41) with LEL group,and the difference of incidence and volume of the pneumothorax between two groups was statistically signifieant(X2 =9.981,P =0.019).When the distance was larger than 2 cm( >2 cm),the incidence and volume of pneumothorax between two groups were not significant statistically.The average retention time of the biopsy needle in the lung parenchyma was (7.2±1.8)s with EPL group and (58.3±11.6) s with LEL group.Conclusion The extrapleural locating method can reduce effectively the retention time of the biopsy needle in the lung parenchyma and the incidence and volume of pneumothorax in CT-gnided transthoracic pulmonary biopsy.

Objective To compare the iodine contrast agent dosage,radiation dose and image quality in CT pulmonary angiogra-phy (CTPA)with low tube voltage and high tube current in 64-slice spiral CT.Methods 60 patients with suspected pulmonary em-bolism in our hospital were randomly chosen and divided into three groups:Group Ⅰ:20 patients,using 120 kV,180 mA,contrast dose of 70 mL.Group Ⅱ:20 patients,using 100 kV,280 mA,contrast dose of 50 mL.Group Ⅲ:20 patients,using 80 kV,automat-ic tube current modulation techniques (300-500 mA),comparative dose of 30 mL.CT values and image noise of three pulmonary central areas and a segment branch were measured in each group.Objective indicators,subjective image quality assessment,CT dose index volume (CTDIvol),dose-length product (DLP)and effective absorbed dose (ED)were compared in three groups to evaluate the value of low kV,high mA with low-contrast dose in CTPA.Analysis of variance and t-test was used for data analysis.Results Compared with those of the standard method of CTPA,all pulmonary dry in two groups of low dose were well displayed.There was no statistical significance between each two groups in image quality score (P > 0.05),but was statistical significance in CT values, noise,SNR and CNR (P < 0.01).The CT radiation dose,CTDIvol and DLP of Group Ⅱ and Group Ⅲ were significantly lower than those of Group Ⅰ (P < 0.01).Conclusion Compared with traditional methods,low dose contrast agent injections under 80 kV could reduce the dose of contrast agent and the effect of hardening artifacts due to contrast agent in superior vena cava on right pul-monary artery.It is helpful to reduce the risk of contrast induced nephropathy and reduce patients’exposure to X-ray radiation.

Objective To investigate the effect of spectral CT monochromatic images for improving imaging quality in hepatic venography.Methods Thirty patients underwent spectral CT examination on a GE Discovery CT 750 HD scanner.During portal phase,1.25 mm slice thickness polychromatic images and optimal monochromatic images were obtained,and volume rendering and maximum intensity projection were created to show the hepatic veins respectively.The overall imaging quality was evaluated on a five-point scale by two radiologists.Inter-observer agreement in subjective image quality grading was assessed by Kappa statistics.Paired-sample t test were used to compare hepatic vein attenuation,hepatic parenchyma attenuation,CT value difference between the hepatic vein and the liver parenchyma,image noise,vein-to-liver contrast-to-noise ratio (CNR),the image quality score of hepatic venography between the two image data sets.Results The monochromatic images at 50 keV were found to demonstrate the best CNR for hepatic vein.The hepatic vein attenuation[(329 ± 47) HU],hepatic parenchyma attenuation [(178 ± 33) HU],CT value difference between the hepatic vein and the liver parenchyma [(151 ± 33) HU],image noise (17.33 ±4.18),CNR(9.13 ±2.65),the image quality score(4.2 ±0.6) of optimal monochromatic images were significantly higher than those of polychromatic images[(149 ± 18) HU],[(107 ± 14) HU],[(43 ±11) HU],12.55 ± 3.02,3.53 ± 1.03,3.1 ± 0.8 (t values were 24.79,13.95,18.85,9.07,13.25 and 12.04,respectively,P ＜ 0.01).In the comparison of image quality,Kappa value was 0.81 with optimal monochromatic images and 0.69 with polychromatic images.Conclusion Monochromatic images of spectral CT could improve CNR for displaying hepatic vein and improve the image quality compared to the conventional polychromatic images.

BACKGROUND:Displacement of the distal fracture fragment is one of the most important facts that lead to cubitus varus fol owing pediatric supracondylar humeral fracture. Mainstream technique emphasized the restoration of posterior-ulnar deviation of the distal fragment. However, there is an absence of supportive evidences from biomechanical studies. OBJECTIVE:To establish models of extension-ulnar type of supracondylar humeral fracture and investigate the mechanical stability of reduced fracture with residual displacements within functional restoration standard, so as to provide mechanic evidences supporting the empirical rule of manipulative reduction-“better anterior than posterior, better radial than ulnar”. METHODS:The fresh cadaveric bone of right upper extremity from a 7-year-old child was scanned using CT. Models of supracondylar humeral fracture differing in contact area of the fracture site and displacement direction of the distal fragment were established and underwent loading tests. Stress in both anterior and posterior margin of the fracture site and Baumann angle were recorded, and data were analyzed and compared. RESULTS AND CONCLUSION:In comparison of stress in the posterior margin, the value was significantly greater in the posteromedial-displacement group than the others. Stress value in fracture with 75%contact area was significantly greater than the other three groups. In comparison of stress in the anterior margin, a significantly greater value was obtained in the posteromedial-displaced group. Stress value in fracture with 85%contact area was significantly greater. When comparing stress in posterior margin and anterior margin, the absolute increment of stress value was greater in posterior displacement group than in anterior displacement group. Baumann angle increased significantly when fragment displaced medial y. Above findings indicated that displacement direction altered the location of stress concentration. Stress augmentation was greater in posterior displacement group. Stress in related area significantly increased constantly when contact area of the fracture site reduced. Baumann changed obviously when fragment displaced medial y. The results preliminarily verify the hypothesis that displacement of the distal fragment was the main contributor to cubitus varus fol owing supracondylar humeral fracture. These findings provided certain evidences supporting the empirical rule“better anterior than posterior, better radial and ulnar”.

Objective To investigate the changes of plasma thrombomodulin (TM),tissue factor (TF),tissue factor pathway inhibitor (TFPI),P-selectin (P sel),von Willebrand factor (vWF) and D-dimer (D-D) levels in patients with hemorrhagic fever with renal syndrome (HFRS) and its clinical significance.Methods Twenty-three cases of HFRS were divided into two groups according to the severity of disease (12 cases in mild group and 11 cases in severe group),and 20 healthy individuals served as control group.Blood samples were collected at every stage of the disease.Plasma TM,TF,TFPI,P-sel and vWF were measured by enzyme-linked immunosorbent assay (ELISA); plasma D-D was detected by nanoparticles enhanced turbidimetric immunoassay; creatine kinase MB isoenzyme (CKMB) was tested by immunosuppression assay; blood clotting time was recorded for blood coagulation functions; blood urea nitrogen (BUN),creatinine (Cr),alanine aminotransferase (ALT),aspartate aminotransferase (AST),and platelets (PLT) were also routinely tested.The comparison between groups was done by analysis of variance and two sided t test.Results During the acute phase of HFRS,the plasma levels of TM,TF,P-sel,vWF and D-D were significantly increased,activated partial thromboplastin time (APTT) was prolonged,international normalized ratio (INR) was elevated,while fibrinogen (Fn) and PLT were decreased markedly as compared to control group.In febrile phase,there were significant differences between severe group and mild group in plasma TM [(1.78±1.00) μmol/L vs (1.33±0.35) μmol/L,t=2.600,P＜0.01],TF [(36.63±8.48) ng/L vs (32.93±10.61) ng/L,t=3.423,P＜0.01],vWF [(327.1±57.2) μg/L vs (260.3±63.2) μg/L,t=2.257,P＜0.01],APTT [(63.9±20.5) s vs (48.7±18.6) s,t=4.920,P＜0.01],and INRlevels(1.8±0.6 vs 1.5±0.4,t=2.276 P＜0.05).The variation curves of TM,P sel,APTT,INR and D-D were similar to those of BUN and ALT,but contrary to PLT count.Conclusions There are significantly elevated plasma levels of TM,vWF,P sel and D-D,prolonged APTT,increased INR,and much decreased plasma Fn and PLT in the acute phase of HFRS,suggesting the presence of extensive capillary injuries and activation of platelet and coagulation system,which is closely associated with kidney,liver and cardiac muscle damage.Hence,it is essential to use antiviral agents,anticoagulants and fluid resuscitation in the early stage of the disease.

Objective To establish a simple and rapid detection technique for Oncomelania infected with Schistosoma japonicum(SJ), with high sensitivity and good specificity .Methods The gene fragment of SJ was amplified by PCR , and cloned into the T-vector to construct positive-reference.An isothermal nucleic acid amplification reaction system for detecting Oncomelania infected with SJ was set up , and its sensitivity was analyzed by detecting positive-reference diluted according to geometric proportion , and its specificity by detecting the genomic DNA of relative samples .Then, a corresponding means of purifying nucleic acid was designed to assemble a reagent detecting Oncomelania infected with SJ . This reagent was validated by detecting Oncomelania samples.Results The 213 bp amplified products were obtained and used to construct recombination T-vector for positive reference .An isothermal nucleic acid amplification reaction system was set up for detecting Oncomelania infected with SJ , and the amplification results could be simply determined by color change, with better sensitivity and specificity .The reagents for detecting Oncomelania infected with SJ were assembled , which could detect samples containing only 1% infected Oncomelania.Conclusion A visible detection method for Oncomelania infected with SJ is successfully established and validated .

Objective To discuss the treatment of periprosthetic femoral fractures (PFF) with unstable prosthesis by replacement of long-stem femoral prosthesis and internal fixation.Methods From December 2005 to December 2014,15 PFF patients with unstable prosthesis (15 hips) following were treated at our department.They were 10 men and 5 women,aged from 64 to 89 years (mean,76.2 years).Their primary surgeries included total hip arthroplasty in 13 cases and biological bi-polar replacement of femoral head in 2.Two prostheses were cement and 13 biological.By Vancouver classification,9 cases were type B2,and 6 type B3.The unstable prostheses in the 15 cases were replaced by long-stem femoral ones,followed by internal fixation.At the last follow-ups,clinical outcome were evaluated by Harris scoring and images of PFF by Beals & Tower criteria.Complications were documented.Results One died 4 months after operation.The other 14 patients were followed up for an average of 4.5 years (from 6 months to 9 years).Fracture union was achieved in 12 cases after an average of 3.9 months (from 3 to 9 months).Nonunion occurred in 2 cases.Imaging evaluation revealed 9 excellent cases,3 good ones and 2 poor ones.The Harris scores at the last follow-up averaged was 82.3 points (from 50 to 100 points).Deep vein thrombosis occurred preoperatively in one case and posterior tibial vein thrombosis occurred in 2 cases respectively on day 3 and day 10 postoperatively.No such complications occurred as malunion,fixation failure,dislocation or prosthesis loosening.Conclusion Satisfactory outcomes can be achieved by replacement of long-stem femoral prosthesis combined with appropriate fixation for treatment of PFF with unstabrosthesis.

A total of 68 patients with histologically proven endometrial cancer were preoperatively evaluated with a 3.0 T magnetic resonance (MR) unit.Two radiologists interpreted the depth of myometrial invasion on T2-weighted and diffusion-weighted(DW) MR (b =700 s/mm2) imaging.Myometrial tumor spread was classified as superficial (＜ 50％) or deep (≥50％ myometrial thickness).Statistical methods included Kappa statistics for reader agreement,accuracy assessment and receiver operating characteristic analysis for diagnostic performance comparison.For assessing the depth of myometrial invasion,the diagnostic accuracy,sensitivity and specificity were as follows:T2-weighted imaging-reader 1st,61.8％,60.0％ and 65.2％;reader 2nd,66.2％,64.4％ and 69.6％ ; T2-weighted combined DW imaging-reader 1st,86.8％,84.4％and 91.3％ ; reader 2nd,89.7％,86.7％ and 95.7％.Reader agreement was excellent for T2-weighted combined DW imaging (Kappa =0.818).For assessing deep myometrial involvement,ROC analysis showed that the diagnostic accuracy was significantly higher on T2-weighted combined DW imaging than that on T2-weighted imaging.The AUC (area under the curve) values measured by two readers on T2-weighted and T2-weighted combined DW imagings were 0.626,0.879 and 0.670,0.912 respectively.The addition of 3.0T MR diffusion-weighted to T2-weighted imaging can improve the diagnostic performance of MR imaging in the assessment of myometrial invasion.

Objective To investigate the CT performances and causes of misdiagnosis of parovarian cyst,to improve its diagnostic accuracy.Methods CT data of 75 patients with surgically and pathologically confirmed parovarian cyst were analyzed retrospectively. Results Among the 75 patients,there were 79 cysts,in which 48 patients (51 cysts)originated from the epoophoron and 27 patients (28 cysts) from the mesosalpinx.77 were simple serous cysts and 2 serous cystadenomas.38 were located in the right ovarian adnexa,36 in the left ovarian adnexa,3 in the anterosuperior uterus,1 in the rectouterine pouch and 1 in the right iliac fossa.The size of the cysts ranged from 10 mm × 13 mm to 174 mm × 227 mm.75 were single cysts and 4 double cysts,34 presented as ovoid cysts,25 as irregular cysts, 17 as round cysts and 3 as gourd-shaped cysts.All the 79 cysts showed clear boundaries,thin walls,non-mural nodules,cystic fluid with a homogeneous densitywith CT value of 0-31 HU.Enhanced scanning revealed curved “obvious enhancement of the fallopian tube”at the edge of 68 cysts.In addition,the ipsilateral ovary could be detected in 76 cysts.“Holding ball”was found in 1 9 cysts.Conclusion Indication in ipsilateral ovary,curved “obvious enhancement of the fallopian tube”at the edge of cysts and “holding ball”are distinctive CT performances of parovarian cysts.CT has an important diagnostic value in parovarian cyst.