Objective To investigate the image quality,radiation dose and iodine intake of CT pulmonary angiography (CTPA) in patients using low tube voltage (100 kVp) combination of different noise indexes (NI) and low concentration contrast agent.Methods A total of 80 patients with suspected pulmonary embolism (PE) and other pulmonary diseases who had undergone CTPA were divided into four groups (A,B,C and D),with 20 patients in each group.Group A underwent 120 kVp CT scan protocol in combination with NI=25 and 370 mg iodine/ml contrast agent,while groups B,C and D underwent 100 kVp CT scan protocol in combination with NI=30,35,40,and 320 mg iodine/ml contrast agent,respectively.All images were restructured using 60％ adaptive statistical iterative algorithm 2.0.Objective image quality evaluation included CT values of pulmonary artery,noise values of pulmonary artery,signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR).Subjective image evaluation used a 5-point scoring method and was conducted by two independent radiologists.The CT dose index of volume (CTDIvol),dose-length product (DLP) and iodine intake was recorded,and the mean value was calculated.The DLP was converted to the effective dose (ED).Analysis of Variance or Kruskal-Wallis test was used to evaluate the differences among the four groups in terms of image quality,radiation dose and iodine intake.Results There was a significant difference in CT values of pulmonary artery among the groups A,B,C and D (P＜0.05),and the CT values of pulmonary artery of group A was the lowest.There was no significant differences in noises of pulmonary artery,SNR,CNR and subjective indexes scores among the groups A,B,C and D (P＞0.05).There was a significant difference in iodine intake among the groups A,B,C and D,iodine intake of the group A was the highest,iodine intake of the group D was the lowest.The iodine intake of groups B,C and D decreased by 12.4％ (42/340),13.2％ (45/340) and 15.0％ (51/340) relative to group A,respectively.There was a significant difference in radiation dose among the groups A,B,C and D,The CTDIvol,DLP and ED of group D decreased by 45.3％ (3.9/8.6),48.6％ (120/247) and 48.3％ (2.02/4.18) relative to group A,respectively (P＜0.01).Conclusion Low tube voltage combination with high NI value and low concentration contrast agent can more effectively reduce the radiation dose and iodine intake for CTPA while maintaining diagnostic image quality.

Objective To investigate the effect of different noise index (NI) combined with iterative recombination on the image quality and radiation dose of CT scan in patients with different body mass index (BMI). Method One hundred and sixty patients who had a liver CT enhanced scan were divided into group A (18 kg/m2≤BMI<24 kg/m2 ) and group B (24 kg/m2≤BMI<31 kg/m2) according to BMI, and each group had 80 patients. The two groups were randomly divided into 4 subgroups which NI value was 11, 13, 15 and 17 respectively. All images were restructured with 50% adaptive statistical iterative reconstruction. Subjective evaluation, objective evaluation [signal noise ratio (SNR) and contrast noise ratio (CNR)] and the effective dose of each group were recorded and calculated after the scan. ANOVA and Kruskal-Wallis test were used to evaluated the difference of imaging quality and radiation dose. Results In group A, the SNR, CNR and the subjective score of the later arterial phase images showed a statistical difference between NI=17 group and other subgroups (P<0.05), while there was no statistical differences among the other three subgroups during three CT enhanced phase. The average ED of NI=15, 17 group were decreased by 57.56%(2.17/3.77) and 61.54% (2.32/3.77) compared with NI=11 group, respectively. In group B, the SNR, CNR and the subjective image scores of the later arterial phase showed a significant difference between NI=15 and NI=11, 13 group (P<0.05). There was a statistically difference of image quality in group NI=17 compared with the other three subgroups in the later arterial phase, portal venous phase and equilibrium phase (P<0.05). The average ED of NI= 13, 15 group was decreased by 26.41% (1.69/6.40) and 45.31%(2.90/6.40) compared with NI=11 group, respectively. Conclusion Upon maintaining diagnostic imaging quality, setting different NI according to BMI and applying the iterative reconstruction algorithm can effectively reduce the radiation dose of liver CT enhanced scanning.

Objective To compare the image quality and radiation dose of CTA of the kidney in patients using routine CT and the spectral imaging combination of different scanning protocols with the adaptive statistical iterative reconstruction 2.0 algorithm (ASIR 2.0). Methods A total of 90 patients who had undergone a CTA of the kidney were divided into three groups (A, B and C), with 30 patients in each group. Group A underwent a routine CT examination, and the scan parameters are:120 kVp, 30 to 650 mA, rotation time 0.5 s/r, scan FOV 50 cm × 50 cm;while groups B and C underwent spectral imaging protocol 1 and 2, the scan parameters of spectral imaging protocol 1 and 2 are:rapid dual kVp (80-140 kVp) switching in 0.25 ms, 375 mA and 360 mA, rotation time 0.7 s/r and 0.6 s/r, scan FOV 36 cm × 36 cm and 32 cm × 32 cm, respectively. All images were reconstructured using ASIR 2.0. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated when the kidney CTA was completed. Each subjective image evaluation used a 5-point scoring method and was conducted by two independent radiologists. The CT dose index (CTDIvol) and dose-length product (DLP) were recorded, and the mean value was calculated. The DLP was converted to the effective dose (ED). All data were compared with Kruskal-Wallis test and one-way ANOVA. Results The energy level of 49 to 56 keV was found to provide the best CNR for displaying CTA of the kidney. There were significant differences in CT values, noise, SNR, CNR and subjective score between groups B, C and A (P<0.05), and there was no significant differences in CT values, noise, SNR, CNR and subjective score between groups B and C (P>0.05). There were significant differences in ED among groups A, B and C (P<0.05), and the ED of groups A, B and C were (8.2±1.2), (5.2± 0.9) and (4.4 ± 0.7) mSv, respectively. Conclusion Spectral imaging with different scanning protocols can more effectively reduce the radiation dose than the routine CT scan mode for a kidney CTA while still maintaining diagnostic image quality, and protocol 2 of spectral imaging in our study is recommended.

Adult ; Cleidocranial Dysplasia ; genetics ; pathology ; Female ; Humans ; Male ; Middle Aged

Objective:To compare the diagnostic value of three quantitative evaluation methods based on three-dimensional rapid fluid attenuation inversion recovery sequence (3D-FLAIR) vein-enhanced labyrinth images in endolymphatic hydrops.Methods:From October 2017 to April 2019, a retrospective study was conducted on 86 patients with unilateral otogenic vertigo who were admitted to Beijing Tongren Hospital, Capital Medical University. MRI was performed 8 h after the single-dose Gd-DTPA intravenously injection in all patients. Three evaluation methods were used to calculate the ratio of the endolymphatic area to the total lymphatic area, the ratio of the saccule to utricle area, and the ratio of the endolymphatic volume to the total lymphatic volume, respectively. The paired t test was used to compare the three ratios between the affected and healthy ears. With clinical diagnosis as the gold standard, the receiver operating characteristic (ROC) curve analysis was used to analyze the efficacy of three methods in diagnosing endolymphatic hydrops. Results:Totally 65 cases were finally diagnosed endolymphatic hydrops clinically. There were statistically significant differences of all the 3 ratios between the affected and healthy ears ( t=9.93, 7.22, 8.20, all P<0.001). The ROC curve showed that the area under the curve (AUC) of endolymph/total lymph area ratio, saccule/utricle area ratio, endolymph/total lymph volume ratio for diagnosis of endolymphatic hydrops were 0.882, 0.768, 0.884 (all P<0.001). And there were no significant differences between each paired AUCs (all P>0.05). Conclusions:All three methods of endolymph/total lymph area ratio, saccule/utricle area ratio, endolymph/total lymph volume ratio can quantitatively evaluate endolymphatic hydrops. The endolymphatic/total lymphatic area ratio method is still the most convenient method at present.

Objective:To explore the clinical application value of each sequence by analyzing the characteristics of labyrinthine signal on MRI in patients with unilateral sudden deafness.Methods:Totally 52 patients of unilateral sudden deafness with inner ear MRI were analyzed retrospectively at Beijing Tongren Hospital, Capital Medical University from January 2016 to July 2019, all of which could find abnormalities in the labyrinth, including 17 cases of plain scan and 35 cases of enhanced scan, with sequences including plain T 1WI, enhanced T 1WI, plain and enhanced delayed 3D fluid attenuation inversion recovery (3D-FLAIR). The affected labyrinthine signal characteristics of each sequence were analyzed and the involvement sites were judged. The ability of each sequence to show labyrinthine abnormal signal was evaluated and scored. The Friedman test and Wilcoxon signed rank sum test were used to compare the subjective scores of the ability to show labyrinthine high signal in different sequences in plain and enhanced patients, respectively. Fisher′s exact probability method was used to analyze the relationship between the affected sites and the recovery of hearing, tinnitus and vertigo symptoms. Results:Fifty-two patients (100%, 52/52) showed labyrinthine high signal on T 1WI, 8 (15.4%, 8/52) showed higher signal and 3 (5.8%, 3/52) showed low signal on T 2WI. Thirty-five (100%, 35/35) showed high signal on enhanced T 1WI, among which 27 had enhancement (77.1%, 27/35). Fifty-two (100%, 52/52) showed significant high signal of the affected labyrinth on 3D-FLAIR (17 plain scan, 35 enhanced scan). The scores were 2 (2, 2), 3 (2, 3), 3 (3, 4) and 4 (4, 4) of T 1WI, enhanced T 1WI, plain and enhanced 3D-FLAIR respectively. The overall difference in subjective scores of plain T 1WI, enhanced T 1WI and enhanced 3D-FLAIR in enhanced patients was statistically significant (χ2=64.528, P<0.001), and the comparison between the two was statistically different (all corrected P<0.05). The plain 3D-FLAIR score was higher than the plain T 1WI in patients with a statistically significant difference ( Z=-3.729, P<0.001). Twenty-seven cases (51.9%, 27/52) exhibited high signal at the ampulla of semicircular canals, with a statistically significant difference in the distribution of hearing recovery or not ( P=0.001). Conclusions:Both T 1WI and 3D-FLAIR sequences can effectively identify the labyrinthine high signal, but the latter was better than the former of its ability to display, especially delayed enhanced 3D-FLAIR. The high signal at the ampulla of semicircular canals was a characteristic predictor of non-recovery of hearing.