Objective To evaluate the imaging quality and radiation doses of dual-source computed tomography (DSCT) coronary angiography at a low tube voltage in patients with medium and low heart rate.Methods Eighty-five patients[heart rate (HR) ＜ 91 beats per minute (bpm); body mass index (BMI) 17. 51-30. 00 kg/m2]suspected of coronary artery disease received retrospectively ECG-gating coronary angiography with dual-source CT scanner (Somatom Definition, Siemens) at a tube voltage of 100 kVp. For all patients, no beta-blocker was used before CT scan. According to the HR, the patients were divided into three groups: Group A, HR ≤ 59 bpm, n = 27; Group B, HR 60-69 bpm, n = 29; Group C,HR ≥70 bpm, n = 29. All images were transferred to a workstation for postprocessing. The best R-R interval reconstruction images of all groups were evaluated. The value of pitch, CT volume dosage index (CTDIvol), dose length product (DLP)and effective dose (ED)were recorded. The pitch, the score of imaging quality of coronary artery segments and the radiation dose were compared with one-way ANOVA. The influence of HR on image quality and radiation doses of coronary artery was analyzed. Results The value of pitch in Group A, Group B and Group C was 0. 241 ± 0. 025, 0. 286 ± 0. 034 and 0. 335 ± 0. 036,respectively. The mean score of imaging quality of coronary artery segments in Group A, Group B and Group C was 4. 78 ± 0. 26, 4. 66 ± 0. 56 and 4. 70 ± 0. 46, respectively. The value of CTDIvol in Group A,Group B and Group C was (18.06 ±5. 16), (19. 62 ±7. 15) and (17. 50 ±7. 13) mGy, respectively. The value of ED in group A, Group B and Group C was (4.23 ± 1.76), (4.59 ± 1.75) and (4.12 ±1.39) mSv, respectively. There was statistical difference in value of pitch among the three groups (F =60. 00, P= 0. 00). There were no statistical difference in score of imaging quality, CTDIvol and value of ED among the three groups (F = 0. 53, P = 0. 59; F = 0. 83, P = 0. 44 ; F = 0. 86, P = 0. 43). Conclusion Medium and low HR have little influences on image quality of dual-source CT coronary angiography at a low tube voltage. When the auto ECG-gating is selected, there is little influence on radiation dosage as well.

Objective To explore the application value of pulmonary artery monitoring program for intracranial and cervical artery angiography with dual-energy CT.Methods Sixty patients performed intracranial and cervical artery angiography with dual-energy CT were divided into two groups according to the random number table.Group A (optimization group,30 patients):the monitoring points were located in the main pulmonary artery,with threshold 150 HU,trigger delay time 8-9 s,pitch 0.9,and the iohexol (350 mg I/ml) 60-65 ml.Group B (conventional group,30 patients):the monitoring points were located in aortic arch,with threshold 100 HU,trigger delay time 5 s,and the iohexol (350 mg I/ml)60-70 ml.Patients with the body weight less than 75 kg were injected with the flow rate of 4.0 ml/s,and those weight greater than 75 kg or with body mass index (BMI) greater than 27 kg/m2 were 4.5 ml/s,following 40 ml saline solution with the same flow rate respectively.All images were transferred to Siemens Syngo workstation for further processing and analysis.The attenuation values were measured on axial images in the common carotid artery,internal and external carotid artery,vertebral and basilar artery,the horizontal segment of the middle cerebral artery,the subclavian vein of injection side,the proximal,middle and distal segment of jugular vein,the straight sinus and the superior sagittal sinus.Two experienced observers blinded independently evaluated the image quality of CTA,the impact of contrast material residues artifacts of subclavian vein of injected side and the affect of venous return factors on arterial image display.Images of volume rendering technique(VR),the maximum intensity projection (MIP),and curved planar reformation (CPR) were reconstructed using dual energy bone removal and Inspace and 3D software.The mean intraluminal attenuation of contrast material (HU),the volume of contrast material and the mean image quality scores were compared with t test between the two groups.Chi-square test was used to compare of image contrast agents residual artifacts,the absence segments of the root of the neck artery,and the degree of the jugular vein return in two groups.Results The mean CT values were 372-414 HU for each segment of artery showing no significant differences between two groups (P ＞ 0.05).In group A,the CT values of the jugular vein in proximal,middle,distal segment of the two sides were (95 ± 36),(95 ± 36),(131 ±58),(133 ± 57),(174 ± 68),and (180 ± 66) HU respectively.In group B,CT values were (135 ± 58),(137 ±59),(170 ±58),(181 ±58),(218 ±62),and (224 ±68) HU.The CT value of jugular venous in group A was significantly lower than that in group B (t =-3.30--2.54,P ＜ 0.05).Case numbers of contrast agent residual artifacts of injection side subclavian vein and the absence segments of root of the neck artery at the beginning in group A (5,11) were less than that in group B (12,24) (x2 =4.02,5.65,P ＜0.05).The degree of the jugular vein return in group A were lesser severely than that in group B (x2 =6.79,6.37,P ＜0.05).Below the level of carotid artery bifurcation:slight 5 patients,severe 1 patient in group A vs.slight 15 patients,severe 9 patients in group B.Above the level of carotid artery bifurcation:slight 9 patients,severe 6 patients in group A vs.slight 12 patients,severe 17 patients in group B.Image quality scores of group A (3.84 ± 0.40) was higher than that of group B (3.64 ± 0.63) (t =4.26,P ＜0.05).Conclusions Pulmonary Artery Monitoring combines with 60-65 ml contrast material optimization scheme for intracranial and cervical artery angiography with dual energy CT can significantly reduce the degree of jugular venous return and contrast material residues artifacts of subclavian vein of injected side.This technique is helpful to improve the work efficiency and image quality.

Objective To evaluate the application value of dual-source CT coronary angiography in low tube voltage setting and the influence of heart rate on image quality and radiation doses.Methods 323 patients suspected of coronary artery disease received retrospective ECG-gating coronary angiography with dual-source CT scanner,who were divided into low tube voltage group (100 kVp,n =201) and conventional voltage group (120 kVp,E group,n =122).No beta-blockers were taken before CT scan.All patients in low tube voltage group were divided into four groups according to the heart rate (HR):group A,HR≤59 beats per minute (bpm),n =50; group B,60≤HR ＜69 bpm,n =64; group C,70≤HR ＜91bpm,n =62;group D,HR ≥ 91 bpm,n =25.All images were transferred to a workstation for further processing.The best R-R interval reconstruction images of all groups were evaluated.The value of pitch,CT volume dosage index(CTDIvol),dose length product(DLP) and effective dose(E)were recorded.The pitch,the score of imaging quality of coronary artery segments and the radiation dose were compared with One-Way ANOVA.The influence of heart rate on image quality and radiation doses of coronary artery was analyzed.Results The value of pitch in groups A-D was 0.24 ± 0.03,0.29 ± 0.04,0.33 ± 0.05,0.38 ± 0.06,respectively,with statistical difference (F =62.57,P ＜ 0.05).The value of CTDIvol in groups A-E was (21.59±7.97),(20.24±6.03),(18.23±7.55),(18.14 ±5.75),(38.62±16.21)mGy,respectively,with statistical difference (F =85.16,P ＜ 0.05).The value of E in group A-E was (5.31 ±2.18),(4.85 ±1.70),(4.49 ± 1.86),(4.37 ±1.50),(8.75 ± 4.07) mSv,respectively,with statistical difference(F =44.83,P ＜ 0.05).The image score was (4.65 ±0.46),(4.55 ± 0.53),(4.55 ±0.53),(4.47 ±0.72),(4.66 ± 0.44) (F =1.89,P ＞ 0.05).Conclusions No beta-blockers was taken before CT scan,and a high quality image could be acquired by using dual-source CT coronary angiography in low tube voltage setting(100 kVp).When the auto ECG-gating is selected,medium and low HR have little influences on radiation dose,while the radiation dose could be decreased significantly at higher HR,but the possibility to obtain the high quality image decreased.

Objective To investigate antimicrobial resistance among gram-positive cocci in China in 2009. Methods From June to December 2009, 1169 consecutive and non-repetitive gram-positive cocci were collected from 12 teaching hospitals at 9 cities. The minimal inhibitory concentration (MIC) of antibacterial agents was determined by agar dilution method. Results The prevalences of methicillinresistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococci (MRCoNS) were 45.3% (211/466) and 89. 5% (214/239), respectively. The isolation rate of MRSA was 33. 3%-68. 1% from different samples. All Staphylococci isolates were susceptible to vacomycin, teicoplanin and linezolid. Five point five percent (7/128) E. faecium strains were resistant to vacomycin. All E.faecalis strains were susceptible to vacomycin. About 99. 1% (108/109) of E. faecalis and E. faecium were susceptible to linezoild. The prevalence of penicillin-intermediate Streptococcus pneumoniae (PISP) was 21.6% (48/222). Only 1 (0. 5%, 1/222) Streptococcus pneumoniae strain was resistant to penicillin.Teicoplanin, vancomycin, linezolid and tigecycline were the most active agents against Streptococcus pneumoniae (susceptible rate 100% ). Conclusions The high prevalence of methicillin-resistance is among Staphylococcus strains. Different samples show a different MRSA prevalence. Teicoplanin, vancomycin and linezolid show very high activity to Staphylococci,E. faecalis, E. faecium and Streptococcus pneumoniae.

Objective To investigate antimicrobial resistance among gram-positive cocci in China in 2008.Methods From June 2008 to December 2008,1171 consecutive and non-repetitive gram-positive cocci were collected from 12 teaching hospitals.The MICs of antibacterial agents was determined by agar dilution method.Results The prevalence of MRSA and methicillin-resistant coagulase-negative Staphylococci(MRSCoN) was 49.9%(232/465) and 74.0%(179/242),respectively.The MRSA prevalence ranged from 33.3% to 65% in different regions.About 71.1%(108/152) of Staphylococcus aureus from respiratory tract specimens,48.3%(28/58) of Staphylococcus aureus from blood samples,and 36%(68/189) of Staphylococcus aureus from the pus,wound and sterile body fluid samples were resistant to methicillin.The susceptible rates of MRSA to trimethoprim/sulfamethoxazole(SXT) and chloramphenicol were 81.5%(183/232) and 89.7%(208/232).Susceptibility to gentamicin, erythromycin, clindamycin, tetracyclines,rifampicin,and quinolones were from 3.9% to 35.0%.All Staphylococci isolates were susceptible to vancomycin,teicoplanin,and linezolid.Three vacomycin-resistant Enterococcus faecium strains were found in this study.About 96.2%(101/105) of Enterococcus faecalis and 97%(130/134) of Enterococcus faecium were susceptible to linezoild.Fifty-one out of 105 of Enterococcus faecalis(48.6%)and 101 out of 134 Enterococcus faecium(75.4%)were resistant to high concentration gentaroicin.The susceptibility of Enterococcus faecalis to all the antibiotics except for chloramphenicol and tetracycline was higher than that of Enterococcus faecium.Enterococcus faecium isolates showed a high resistant prevalence to most of antibiotics except glycopeptides and linezolid.The prevalence of PISP among 225 isolates was was 36.6%(15/41),and the prevalence of PNSSP from the other patients ranged from 15.4% to 26.6%.The susceptible rates of PSSP to cefprozil,cefuroxime and cefaclor were 67.5%(114/169),66.3%(112/169) and 61.5%(104/169),respectively.All the PISP isolates were resistant to the above three antibiotics.Teicoplanin,vancomycin and linezolid were the most active agents against Staphylococcus pneumoniae(susceptible rate,100%).About 96.9%,97.8% and 98.2% Staphylococcus pneumoniae isolates were susceptible to gatifloxacin,levofloxacin,and moxifloxacin,respectively.The susceptible rates of Staphylococcus pneumoniae to ceftriaxone,chloramphenicol and amoxicillin/clavulanic acid were 81.3%,77.3%,and 68.0%,respectively.The susceptibility of Staphylococci pneumoniae to macrolides,SXT and tetracycline ranged from 11.6% to 23.6%.Conclusions The prevalence of VRE is low in China.However,methicillin-resistance among Staphylococci isolates was high.The prevalence of PNNSP isolated from (≤)3 years children is higher than in the other age population.Teicoplanin,vancomycin,and linezolid remain high activity against Staphylococci,Enterococcus faecalis,Enterococcus faecium,and Staphylococcus pneumoniae.

Objective To investigate antimicrobial resistance among gram-positive cocci in China in 2006.Methods From Jun 2006 to Dec 2006,674 consecutive and non-repetitive gram-positive bacteria were collected from 7 teaching hospitals.The minimal inhibitory concentration(MICs)of antibacterial agents were determined by agar dilution method.Results The prevalence of penicillin.resistant(ease)and pemcllhn. intermediate S.pneumoniae(PISP)among 100 isolates was l%and 19%,respectively.Teicoplanin and vancomycin were the most active agents against S.pneumoniae.97% and 98% S.pneumoniae isolates were susceptible to levofloxacin and moxifloxacin,respectively.The susceptibility of amoxicillin/clavulanic acid, ceftriaxone and chloramphenicol are 96%,87% and 73%,respectively.The susceptible rates of penicillin. susceptible S.pneumoniae(PSSP)to cefprozil and cefaclor were 62% and 55.7%,respectively.All the PISP and PRSP isolates were resistance to the two antibiotics.The susceptibility to macrolides,trimethoprim/ sulfamethoxazole and tetracycline was lower than 35%.The prevalence of methicillin-resistant Staphylococcus aureus(MRSA)and methicillin.resistant coagulase-negative Staphylococci(MRSCON)was 48%(33%-84%)and 81%(69%-94%),respectively.The susceptible rates of MRSA to trimethoprim/ sulfamethoxazole,chloramphenicol,rifampin,and the other antibiotics in this study were 72%,66%and 45%,respectively.The susceptible rate of MRSA to marcrolides,aminoglycosides,tetracyclines and quinolones were not more than 18%.56%(30%-86%)of E.faecalis and 80%(50%.100%)of E.faecium were highly resistant to gentamicin.The susceptibility of E.faecalis to all the antibiotics except chloramphenicol and tetracycline were higher than E.faecium.All isolates of S.aureus,CoNS and E.faecalis tested were susceptible to vacomycin and teicoplanin.There were two vacomycin.resistant E.faecium strains isolated from Hangzhou.Conclusions Antimicrobial resistance patterns of gram.positive cocci differed in different regions.The resistance of gram-positive cocci to the antibiotics in this study this year was a little higher than the data of the year of 2005.Teicoplanin and vancomycin remained very high activity to gram-positive cocci.

Objective To investigate antimicrobial resistance among gram-positive cocci in 14 teaching hospitals in China in 2011.Methods From June 2011 to December 2011,1498 consecutive and non-repetitive gram-positive cocci were collected from 14 teaching hospitals.The minimal inhibitory concentration (MIC) of antibacterial agents was determined by agar dilution method.A retrospective study was conducted on rates of resistance to antimicrobial agents.Data was compared using chi-square test.Results The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillinresistant coagulase-negative Staphylococci (MRCoNS) was 43.7％ (222/508),and 85.6％ (214/250),respectively.The MRSA prevalence ranged from 20.0％ to 63.5％ in different regions.About 58.2％ (82/141) of Staphylococcus aureus from respiratory tract specimens,44.8％ (48/107) of Staphylococcus aureus from blood samples,and 23.8％ (31/130) of Staphylococcus aureus from pus and wound were resistant to methicillin.The susceptible rates of MRSA to chloramphenicol and sulfamethoxazole-trimethoprim SXT were 94.1％ (209/222) and 83.3％ (185/222),respectively.Susceptibility to gentamycin,erythromycin,clindamycin,tetracyclines,rifampicin and quinolones were from 11.3％ to 52.3％.All Staphylococci isolates were susceptible to vancomycin,teicoplanin,linezolid and daptomycin.Five vancomycin-resistant enterococcus (VRE) strains were found in this study.All enterococcus isolates were susceptible to daptomycin(268/268),and 98.3％ (118/120) of E.faecalis and 99.3％ (147/148) of E.faecium were susceptible to linezoild.About 45.9％ (68/148) of E.faecalis and 67.5％ (81/120) of E.faecium were resistant to high concentration gentamycin.The susceptibility of E.faecalis to all the antibiotics except for chloramphenicol and tetracycline was higher than that of E.faecium.The prevalence of penicillinnonsusceptible Streptococcus pneumoniae (PNSSP) was 15.5％ (37/239).The prevalence of PNSSP in children below 3 years-old was 25％ (13/52),and the prevalence of PNSSP from other patients was 13％(24/187).About 91.6％ (219/239),88.7％ (212/239) and 88.3％ (211/239) of S.pneumonia was resistant to erythromycin,clindamycin and tetracyclines.All S.pneumoniae strains were susceptible to teicoplanin,vancomycin,linezolid,tigecycline and daptomycin.Penicillin still showed high activity against Streptococcus spp.β-hemolytic group.More than 60％ of Streptococcus.spp.β-hemolytic group are resistant to erythromycin,clindamycin and tetracyclines.Conclusions Based on regions,the resistance rates of Gram-positive cocci are different,of which,the increasing tendency should be taken seriously.Teicoplanin,vancomycin,linezolid,tigecycline and daptomycin show very high activity against Gram-positive cocci.

Objective Toinvestigateantimicrobialresistanceamonggram-positivecocciinChinain 2013.Methods Retrospectivestudy.FromJune2013toDecember2013,1663consecutiveandnon-repetitive gram-positive cocci were collected from 15 teaching hospitals. The minimal inhibitory concentration ( MIC) of antibacterial agents was determined by agar dilution method. A retrospective study was conducted on rates of resistance to antimicrobial agents. The prevalence of penicillin-resistant Streptococcus pneumoniae ( PRSP) between children and adult patients and the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) between elder group and younger adult patients were compared using chi-square test. Results The prevalence of PRSP in children below 3 years old ( 72. 9%, 51/70 ) was higher than adult patients (55. 2%, 106/192) (χ2 =6. 653,P<0. 05). About 94. 9%(261/275) and (92. 7%,255/275) of S. pneumonia were resistant to erythromycin and clindamycin. All S. pneumoniae strains were susceptible to teicoplanin, vancomycin, linezolid, tigecycline and daptomycin. Penicillin still showed very high activity against Streptococcus spp. β-Hemolytic group. More than 60% of Streptococcus spp.β-Hemolytic group were resistant to erythromycin, clindamycin and tetracyclines. The prevalence of MRSA and methicillin-resistant coagulase-negative Staphylococci(MRCoNS) was 39. 7%(229/576) and 80. 6%(224/278), respectively. The MRSA prevalence ranged from 24. 2% to 70. 0% in different regions. About 52. 6%( 100/190 ) of Staphylococcus aureus from respiratory tract specimens, 38. 5%(40/104)of Staphylococcus aureus from blood samples, and 29. 7%(58/195) of Staphylococcus aureus from wound and pus were resistant to methicillin. The prevalence of MRSA in elder group ( 48. 6%, 84/173 ) was higher than that in younger adult patients (35. 7%, 144/403)(χ2 =8. 322,P <0. 05). The susceptibility rates of MRSA to chloramphenicol and trimethoprim/sulfamethoxazole were 86. 4% ( 244/228 ) and 94. 7% ( 237/228 ) , respectively. Susceptibility rates to gentamycin, erythromycin, clindamycin, tetracyclines, rifampicin and quinolones were ranged from 15. 8% to 59. 6%. All Staphylococci isolates were susceptible to teicoplanin, vancomycin, linezolid, daptomycin and tigecycline. All Enterococcus isolates were susceptible to daptomycin and tigecycline. All E. faecalis ( 158/158 ) and 96. 4% ( 133/138 ) of E. faecium were susceptible to teicoplanin. About 98. 0% ( 150/153 ) of E. faecalis and 97. 1% ( 145/138 ) of E. faecium were susceptible to linezoild. About 45. 8% (70/153) of E. faecalis and 60. 9% (84/138) of E. faecium were resistant to gentamycin with a high concentration. The susceptibility of E. faecalis to all the antibiotics tested exceptchloramphenicolandtetracyclinewashigherthanthatofE.faecium.Conclusions Basedon different age groups and regions, the resistance rates of Gram-positive cocci are different. Teicoplanin, vancomycin, tigecycline, daptomycin, linezolid and tedizolid showed very high activity against Gram-positive cocci. (Chin J Lab Med,2015,38:373-381)

Objective To investigate antimicrobial resistance among gram-negative bacilli in China in 2010.Methods A total of 1 259 consecutive and non-repetitive gram-negative bacilli were isolated from 13 teaching hospitals from September to December in 2010 in China.All of these isolates were sent to the central laboratory for re-identification and susceptibility testing.The MIC of meropenem and other antibacterial agents were determined by agar dilution method.Interpretive results was determined by CLSI M100-S21.Results The activity of 14 antibacterial agents against 845 Enterobacteriaceae isolates was as follows in order:meropenem ( 98.1％,829 ),amikacin ( 94.0％,794 ),imipeuem ( 90.0％,761 ),piperacillin/tazobactam ( 87.5％,739 ),cefepime ( 83.0％,701 ),ertapenem ( 82.4％,696 ),cefoperazone/sulbactam ( 80.3％,678 ),colistin (75.4％,637),ceftazidime (70.0％,591 ),ciprofloxacin (59.1％,499 ),cefoxitin ( 54.8％,463 ),ceftriaxone ( 53.5％,452 ),cefotaxime ( 52.3％,442 ) and minocycline(51.5％,435).The prevalence of ESBL was 61.3％ (106/173) in Escherichia coli,which was much higher than 41.2％ (70/170) in Klebsiella pneumoniae.The susceptibility rate of Klebsiella pneumoniae against meropenem,imipenem,amikacin and colistin were more than 90％,but were highly resistant to ceftriaxone and cefotaxime.Over 80％ of Enterobacter cloacae,Enterobacter aerogenes,Citrobacter freundii,were susceptible to meropenem,amikacin,cefepine,cefoperazone/sulbactam,imipenem,piperacillin/ tazobactam,and ertapenem.The most active antibiotics against Pseudomonas aeruginosa were Colistin (98.4％,182),Amikacin ( 85.9％,159 ),Piperacillin/Tazobactam ( 80％,148 ),Ceftazidime ( 79.5％,147),Meropenem (74.1％,137),Ciprofloxacin (74.1％,137),Cefepime (73.5％,136),Imipenem (71.9％,132) and Cefoperazone/Sulbactam (70.8％,131 ).Less than 37％ of Acinetobacter baumannii isolates were resistant to carbapenems.The susceptible rate to Minocycline was 47.8％.Colistin kept good activity against Acinetobacter baumannii (susceptible rate,97.8％,n =176),The prevalence of Pan-drug resistant P.aeruginosa and A.baumannii was 18.9％ (n =35),and 61.8％ (n =108),respectively.Conclusions Carbapenems remained very high activity against Enterobacteriaceae.Increasing resistance to the antimicrobials agents test among A.baumanni and P.aeruginosa,especially carbapenems among A.baumanni brought great concern.