改变颈椎屈曲角度对平山病特异性MRI征象的影响

Objective To analyze MRI features of different cervical flexion positions in Hirayama disease (HD) and discuss the effects on these features by different cervical flexion angles.Methods The cervical MR images of neutral and different flexion positions (20°, 25°, 30°, 35° ,40°) of 20 patients, who were clinically diagnosed as HD,were studied.At flexion positions, the appearance of anterior shifting of the posterior wall of the cervical dural canal and widening of epidural space was recorded.The maximum sagittal diameters (d) of widened cervical epidural space and the cervical canal sagittal diameters (D) on the same level were measured to calculate d/D value for quantitative evaluation of the two signs.Comparisons of appearance of the signs among different flexion positions were made using F/sher's exact test.Repeated measures analysis of variance (rmANOVA) was used to compare mean d/D values among groups with different positions, and paired comparisons were also performed.Results The appearance of anterior shifting of the posterior wall of the cervical dural canal were different between 20° group (70%, 14/20) and other 4 larger angles groups (100%) (χ2 =5.76, P=0.020).The d/D values were 0.51±0.06,0.54±0.08,0.57±0.09,0.61±0.09,0.59±0.07 respectively at abovementioned 5 flexion positions, which were different among groups( F = 3.450 ,P = 0.013 ).The value was greater at 35° than that at 20° and 25°( P <0.05 ), and it was also greater at 40° than that at 20° ( P < 0.05 ).Conclusion Cervical flexion angle has an effect on anterior shifting of the posterior wall of the cervical dural canal and widening of epidural space.     

改变颈椎屈曲角度对平山病特异性MRI征象的影响

Objective To analyze MRI features of different cervical flexion positions in Hirayama disease (HD) and discuss the effects on these features by different cervical flexion angles.Methods The cervical MR images of neutral and different flexion positions (20°, 25°, 30°, 35° ,40°) of 20 patients, who were clinically diagnosed as HD,were studied.At flexion positions, the appearance of anterior shifting of the posterior wall of the cervical dural canal and widening of epidural space was recorded.The maximum sagittal diameters (d) of widened cervical epidural space and the cervical canal sagittal diameters (D) on the same level were measured to calculate d/D value for quantitative evaluation of the two signs.Comparisons of appearance of the signs among different flexion positions were made using F/sher's exact test.Repeated measures analysis of variance (rmANOVA) was used to compare mean d/D values among groups with different positions, and paired comparisons were also performed.Results The appearance of anterior shifting of the posterior wall of the cervical dural canal were different between 20° group (70%, 14/20) and other 4 larger angles groups (100%) (χ2 =5.76, P=0.020).The d/D values were 0.51±0.06,0.54±0.08,0.57±0.09,0.61±0.09,0.59±0.07 respectively at abovementioned 5 flexion positions, which were different among groups( F = 3.450 ,P = 0.013 ).The value was greater at 35° than that at 20° and 25°( P <0.05 ), and it was also greater at 40° than that at 20° ( P < 0.05 ).Conclusion Cervical flexion angle has an effect on anterior shifting of the posterior wall of the cervical dural canal and widening of epidural space.     

不同体位短臂离心机暴露时心血管及前庭功能的改变

Objective To investigate the changes of human cardiovascular and vestibular functions when exposed to the artificiaI gravity generated by short-arm centrifuge with different body positions.Methods Ten healthy male volunteers were exposed to the artificial gravity at three different body positions:foot towards to the radial direction off the rotation center respectively with 75°,45°and 15°back tilting.Each position underwent on short-arm centrifuge with two sessions that were at 2 G and 3 G (at foot level) respectively.Beat-by-beat arterial blood pressure (BP) and heart rate (HR) were measured before and during the experiment by means of Portapres and calculated parameters,such as stroke volume (SV),cardiac output (CO) and total peripheral resistance (TPR),were obtained by Beatscope software.A subjective scoring was taken for assessing vestibular sensations. Results Six of 10 subjects with 15°posture were terminated both in 2 G and 3 G exposure due to their serious motion sickness symptoms.Comparing to the measurements before exposure,subjects with 45°and 75°posture showed significant increased BP and HR (F=2.79 to 16.44,P<0.05) but SV (F=2.25 or 8.35,P<0.05) while CO had no obvious change.Comparing to the measurements before exposure,subjects with 3 G (45°posture) showed significant incleased TPR (F=2.61,P<0.05).3 G exposure resulted in higher HR than that in 2 G.No significant changes of BP,HR,CO,SV and TPR were found between 45°and 75°postures under same exposure.The scores of vestibular assessment showed increased tendency with the decreased tilt angle.Significantly higher scores were got for 15°posture exposures comparing to others and indicated stronger vestibular stimuli.Conclusions The results suggested that the smaller tilted angle posture would result in mole serious vestibular symptoms.     

中国汉族正常成人第四脑室容积的高分辨率MRI测量

Objective To explore the normal range of the fourth ventricle volume of Chinese adults of the Han nationality and provide morphological data for the construction of database for Chinese Standard Brain.Methods This is a clinical multi-center study.One thousand Chinese healthy volunteers (age range= 18 to 70) recruited from 15 hospitals were divided into 5 groups, i.e., Group A (age range = 18 to 30),B (age range =31 to 40), C (age range =41 to 50), D (age range =51 to 60), and E (age range =61 to 70).Each group contained 100 males and 100 females.All of the volunteers were scanned by MR using T1 weighted three-dimensional magnetization prepared rapid acquisition gradient echo sequence.After three dimension data reconstruction, the volumes of the fourth ventricle were measured at sagittal view by automatic trace of Midobl.2 combined with manual outlining.The difference of volumes of the fourth ventricle between male and female were analyzed by independent sample t test, and among age groups by ANOVA.Pearson's correlation coeffcient was used to characterize the relationship between volumes of the fourth ventricle and age.Results The fourth ventricle volumes of Group A-E were (2.1±0.9), (2.1±0.8), (2.2±0.8), (2.1±1.0) and (2.4±0.8) ml respectively for male; those for female were(2.0±0.7), (1.9±0.6), (18±0.6), (1.9±0.7) and (2.0±0.6) ml respectively.The fourth ventricle volumes of males were significantly larger than those of females ( t = 5.573, P =0.000 ) ; there were no significant differences among the female groups ( F = 1.788, P = 0.130 ) ; there were significant differences among the male groups ( F = 2.639, P = 0.033 ) and multiple comparison found that the 60 years old was the watershed with significant difference ( P < 0.05 ).Correlation between the change of males' volumes and the ages was not strong (r = 0.119, P = 0.008 ), and the females' volumes did not correlated with their ages ( r = 0.041,P = 0.360 ).Conclusion There are gender differences in the fourth ventricle volumes of normal Chinese adults, and changes of the fourth ventricle volume with aging are different between males and females.     

中国汉族正常成人第四脑室容积的高分辨率MRI测量

Objective To explore the normal range of the fourth ventricle volume of Chinese adults of the Han nationality and provide morphological data for the construction of database for Chinese Standard Brain.Methods This is a clinical multi-center study.One thousand Chinese healthy volunteers (age range= 18 to 70) recruited from 15 hospitals were divided into 5 groups, i.e., Group A (age range = 18 to 30),B (age range =31 to 40), C (age range =41 to 50), D (age range =51 to 60), and E (age range =61 to 70).Each group contained 100 males and 100 females.All of the volunteers were scanned by MR using T1 weighted three-dimensional magnetization prepared rapid acquisition gradient echo sequence.After three dimension data reconstruction, the volumes of the fourth ventricle were measured at sagittal view by automatic trace of Midobl.2 combined with manual outlining.The difference of volumes of the fourth ventricle between male and female were analyzed by independent sample t test, and among age groups by ANOVA.Pearson's correlation coeffcient was used to characterize the relationship between volumes of the fourth ventricle and age.Results The fourth ventricle volumes of Group A-E were (2.1±0.9), (2.1±0.8), (2.2±0.8), (2.1±1.0) and (2.4±0.8) ml respectively for male; those for female were(2.0±0.7), (1.9±0.6), (18±0.6), (1.9±0.7) and (2.0±0.6) ml respectively.The fourth ventricle volumes of males were significantly larger than those of females ( t = 5.573, P =0.000 ) ; there were no significant differences among the female groups ( F = 1.788, P = 0.130 ) ; there were significant differences among the male groups ( F = 2.639, P = 0.033 ) and multiple comparison found that the 60 years old was the watershed with significant difference ( P < 0.05 ).Correlation between the change of males' volumes and the ages was not strong (r = 0.119, P = 0.008 ), and the females' volumes did not correlated with their ages ( r = 0.041,P = 0.360 ).Conclusion There are gender differences in the fourth ventricle volumes of normal Chinese adults, and changes of the fourth ventricle volume with aging are different between males and females.     

多层螺旋CT自动毫安技术对腰椎患者扫描剂量减少的可行性研究

Objective To investigate the feasibility of achieving consistent image quality with dose reduction technology in lumber spine MSCT examination with Z-axis automatic tube current modulation (ATCM). Methods Forty-eight patients diagnosed as lumber intervertebral disc protrution scanned twice by MSCT before and after interventional operations with the same coverage from third lumbar vertebra to first sacral vertebra. The first scan (FM) was with fixed tube current of 320 mAs. The follow-up scan was with ATCM with noise index (NI) of 12.0 HU. At the levels of L3-4, L4-5 and 15-S1, image quality, image noise and radiation dose were measured and analyzed. Image quality and radiation dose were compared by paired t-test and the image noise was compared by ANOVA test. Results The dosage of the ATCM had a 31.3% reduction compared with FM, the average DLP was(187.9±66.4)mGy·cm and(273.4±45.4) mGy·cm respectively, where t = 8.205, P < 0.05. The average noise and their deviations for the FM group were (9.8±2.4) HU,(9.9±2.4) HU, and (11.5±3.2) HU at level of L3-4, L4-5, 15-S1, respectively. With ATCM, the average noise was(12.0±0.8) HU, (11.7±0.6) HU, and (11.7±1.4) HU, respectively. There was statistical difference between the two groups (F = 23.31, P < 0.05). The image quality scores for the FM group were (4.7±0.3), (4.5±0.2), (4.5±0.2) and showed no statistical difference to ATCM group (4.6±0.3), (4.5±0.2), (4.5±0.2) at level of L3-4, L4-5, L5-S1, respectively, where t = 1.000, P > 0.050 Conclusion ATCM technique with the noise index setting at 12.0 HU can achieved a 31.3% dose reduction while keep the consistent image quality for lumbar spine MSCT study.     

高性能战斗机飞行员仪表视觉空间定向能力训练效果观察

Objective To explore effectiveness of improving the abilities of instrument visual spatial orientation (IVSO) training for high performance fighter pilots. Methods An IVSO training device was developed.Based on the principles of computer graphics and characteristics of cognition,4 kinds of instrument flight condition patterns were adopted as training profiles.Eleven pilots were trained along these four training profiles for five times,include recognizing and flying by instrument and head-up display respectively in complicated flight sortie or with interference.The reaction time,rate of correct operation,deviation angle of attitude and the adjunctive task completion rate were recorded and compared. Results In pre-and post-IVSO training,the reaction times got with instrument and head-up display in complicated flight sortie were (1.42±0.24)s vs.(0.99±0.13)s and(1.54±0.29)s vs.(1.05±0.12)s respectively while the rates of correct operations were 53.91%±9.12%vs.90.00%±5.88%and 73.09%±12.02%vs.89.18%±6.10% respectively.Deviation angles of roll and pitch in maintaining flight attitude by instrument training were 3.25°±0.60°vs.2.07°±0.25°and 2.41°±0.63°vs.1.87°±0.30°respectively,comparing to 3.08°±1.03°vs.2.06°±0.35°and 2.84°±0.67°vs.1.99°±0.20°in attitude maintenance by head-up display.Adjunctive task correct rates with believing instrument and head-up display were 63.90%±11.15%vs.88.27%±10.23%and 59.73%±12.81%vs.82.09%±9.62% respectively.All differences between pre-and post-IVSO trainings are statistically significant (t=2.47 to 11.03,P<0.01 or P<0.05). Conclusions The adopted instrument flight training can remarkably improve pilot's IVSO abilities.     

应用模拟低剂量法行新生儿头颅CT扫描

Objective To determine the effects of dose reduction on multi-slice spiral CT(MSCT) of neonatal head and assess the lowest possible radiation for acceptable clinical images.Methods Fifty-seven newborns suspected intracranial hemorrhage were entered into the study and underwent MSCT scans.Original images at three anatomic levels (posterior fossa, basal ganglia, centrum semiovale) were collected and synthetic noise was added so as to simulate dose reductions of 25%, 40%, 50% and 70%, respectively by using the noise addition tool.A total of 855 image data sets were obtained for the 57 patients.Original and simulated dose-reduction scan images were analyzed.Image noise and image quality were assessed by two independent experienced pediatric radiologists using diagnostic acceptability score, subjective image noise score on a 5-peint scale and objective noise index.Image noise was measured by respectively placing region of interest (ROI) at cerebellum, thalamus and corona radiata of 3 different slices.And the noise index and mean value was calculated.The degree of inter-observer concordance was determined by Kappa statistical analysis.The Spearman statistical correlations between the noise index and diagnostic acceptability score were performed.Results On the images of original dose and simulated dose reductions of 25%, 40%, 50% and 70%, the diagnostic acceptability was 4.47±0.51, 3.96±0.33, 3.21±0.45, 2.92±0.32, and 1.85±0.57, respectively,the subjective image scores were 1.62±0.48, 1.99±0.48, 2.76±0.81, 3.19±0.67, and 4.27±0.54, respectively, the noise index were 1.90±0.19, 2.17±0.20.2.44± 0.25, 2.68±0.28, and 3.37±0.39, respectively.The two radiologists had good intembserver agreement for diagnostic acceptability (K=0.860, P=0.017) and for image noise scoff ng (K=0.630, P=0.022).There was significant statistical correlation between image noise index and diagnostic acceptability (r= 0.826,P=0.001).At 40% dose reduction to the standard protocol, the noise index was 2.44 and the image quality score was 3.21 which were considered clinically acceptable.Conclusion The study revealed that acceptable imagos could be obtained with mean noise index of 2.44 and 40% dose reduction.     

应用模拟低剂量法行新生儿头颅CT扫描

Objective To determine the effects of dose reduction on multi-slice spiral CT(MSCT) of neonatal head and assess the lowest possible radiation for acceptable clinical images.Methods Fifty-seven newborns suspected intracranial hemorrhage were entered into the study and underwent MSCT scans.Original images at three anatomic levels (posterior fossa, basal ganglia, centrum semiovale) were collected and synthetic noise was added so as to simulate dose reductions of 25%, 40%, 50% and 70%, respectively by using the noise addition tool.A total of 855 image data sets were obtained for the 57 patients.Original and simulated dose-reduction scan images were analyzed.Image noise and image quality were assessed by two independent experienced pediatric radiologists using diagnostic acceptability score, subjective image noise score on a 5-peint scale and objective noise index.Image noise was measured by respectively placing region of interest (ROI) at cerebellum, thalamus and corona radiata of 3 different slices.And the noise index and mean value was calculated.The degree of inter-observer concordance was determined by Kappa statistical analysis.The Spearman statistical correlations between the noise index and diagnostic acceptability score were performed.Results On the images of original dose and simulated dose reductions of 25%, 40%, 50% and 70%, the diagnostic acceptability was 4.47±0.51, 3.96±0.33, 3.21±0.45, 2.92±0.32, and 1.85±0.57, respectively,the subjective image scores were 1.62±0.48, 1.99±0.48, 2.76±0.81, 3.19±0.67, and 4.27±0.54, respectively, the noise index were 1.90±0.19, 2.17±0.20.2.44± 0.25, 2.68±0.28, and 3.37±0.39, respectively.The two radiologists had good intembserver agreement for diagnostic acceptability (K=0.860, P=0.017) and for image noise scoff ng (K=0.630, P=0.022).There was significant statistical correlation between image noise index and diagnostic acceptability (r= 0.826,P=0.001).At 40% dose reduction to the standard protocol, the noise index was 2.44 and the image quality score was 3.21 which were considered clinically acceptable.Conclusion The study revealed that acceptable imagos could be obtained with mean noise index of 2.44 and 40% dose reduction.     

应用模拟低剂量法行新生儿头颅CT扫描

Objective To determine the effects of dose reduction on multi-slice spiral CT(MSCT) of neonatal head and assess the lowest possible radiation for acceptable clinical images.Methods Fifty-seven newborns suspected intracranial hemorrhage were entered into the study and underwent MSCT scans.Original images at three anatomic levels (posterior fossa, basal ganglia, centrum semiovale) were collected and synthetic noise was added so as to simulate dose reductions of 25%, 40%, 50% and 70%, respectively by using the noise addition tool.A total of 855 image data sets were obtained for the 57 patients.Original and simulated dose-reduction scan images were analyzed.Image noise and image quality were assessed by two independent experienced pediatric radiologists using diagnostic acceptability score, subjective image noise score on a 5-peint scale and objective noise index.Image noise was measured by respectively placing region of interest (ROI) at cerebellum, thalamus and corona radiata of 3 different slices.And the noise index and mean value was calculated.The degree of inter-observer concordance was determined by Kappa statistical analysis.The Spearman statistical correlations between the noise index and diagnostic acceptability score were performed.Results On the images of original dose and simulated dose reductions of 25%, 40%, 50% and 70%, the diagnostic acceptability was 4.47±0.51, 3.96±0.33, 3.21±0.45, 2.92±0.32, and 1.85±0.57, respectively,the subjective image scores were 1.62±0.48, 1.99±0.48, 2.76±0.81, 3.19±0.67, and 4.27±0.54, respectively, the noise index were 1.90±0.19, 2.17±0.20.2.44± 0.25, 2.68±0.28, and 3.37±0.39, respectively.The two radiologists had good intembserver agreement for diagnostic acceptability (K=0.860, P=0.017) and for image noise scoff ng (K=0.630, P=0.022).There was significant statistical correlation between image noise index and diagnostic acceptability (r= 0.826,P=0.001).At 40% dose reduction to the standard protocol, the noise index was 2.44 and the image quality score was 3.21 which were considered clinically acceptable.Conclusion The study revealed that acceptable imagos could be obtained with mean noise index of 2.44 and 40% dose reduction.