Purpose To evaluate the application value of CE-Boost technology in head and neck CT angiography(CTA)with low tube voltage,low contrast agent dosage and low injection rate.Materials and Methods A prospective study was conducted on patients who underwent head and neck CTA at Ji'nan People's Hospital Affiliated to Shandong First Medical University from September to December 2023.Using block randomization,patients were divided into group A(n=30)and group B(n=30).Group A underwent conventional scanning with 120 kV tube voltage,50 ml iodinated contrast agent and 5.0 ml/s injection rate;while group B underwent scanning with 100 kV tube voltage,30 ml iodinated contrast agent and 3.0 ml/s injection rate.CE-Boost images(group B2)were generated by performing flexible subtraction between the enhanced images of group B(group B1)and non-contrast images.CT values,noise,signal-to-noise ratio and contrast-to-noise ratio of major vessels were measured and calculated.Subjective image quality was assessed using a 5-point scale.Vascular CT values,noise,signal-to-noise ratio,contrast-to-noise ratio,subjective scores and radiation dose were compared among the three groups.Results No significant differences in noise were observed among group A,B1 and B2(all P>0.05).The aortic arch CT values,signal-to-noise ratio and contrast-to-noise ratio in group B2 were significantly higher than those in group B1 and A(all P<0.05),while group B1 exhibited significantly lower values than group A(all P<0.05).For other vessels,group B2 demonstrated significantly higher CT values,signal-to-noise ratio and contrast-to-noise ratio than group B1(all P<0.05),but no significant differences were found compared with group A(all P>0.05).Subjective scores were significantly higher in group A[5(5,5)point]and group B2[5(5,5)point]than in group B1[4(3,4)point](Z=-4.790,-4.564,both P<0.001),with no significant difference between groups A and B2(Z=-1.076,P=0.163).Group B reduced iodine intake and injection rate by 40%compared with group A(iodine intake:11.1 g vs.18.5 g;injection rate:3.0 ml/s vs.5.0 ml/s)and achieved a 30%reduction in effective radiation dose[(1.02±0.95)mSv vs.(1.44±1.66)mSv,t=12.217,P<0.001].Conclusion For patients with body mass index<28 kg/m2,CE-Boost combined with 100 kV tube voltage,30 ml iodinated contrast agent and 3.0 ml/s injection rate in head and neck CTA significantly reduces radiation dose,iodine load and injection rate while maintaining image quality.

Purpose To evaluate the application value of CE-Boost technology in head and neck CT angiography(CTA)with low tube voltage,low contrast agent dosage and low injection rate.Materials and Methods A prospective study was conducted on patients who underwent head and neck CTA at Ji'nan People's Hospital Affiliated to Shandong First Medical University from September to December 2023.Using block randomization,patients were divided into group A(n=30)and group B(n=30).Group A underwent conventional scanning with 120 kV tube voltage,50 ml iodinated contrast agent and 5.0 ml/s injection rate;while group B underwent scanning with 100 kV tube voltage,30 ml iodinated contrast agent and 3.0 ml/s injection rate.CE-Boost images(group B2)were generated by performing flexible subtraction between the enhanced images of group B(group B1)and non-contrast images.CT values,noise,signal-to-noise ratio and contrast-to-noise ratio of major vessels were measured and calculated.Subjective image quality was assessed using a 5-point scale.Vascular CT values,noise,signal-to-noise ratio,contrast-to-noise ratio,subjective scores and radiation dose were compared among the three groups.Results No significant differences in noise were observed among group A,B1 and B2(all P>0.05).The aortic arch CT values,signal-to-noise ratio and contrast-to-noise ratio in group B2 were significantly higher than those in group B1 and A(all P<0.05),while group B1 exhibited significantly lower values than group A(all P<0.05).For other vessels,group B2 demonstrated significantly higher CT values,signal-to-noise ratio and contrast-to-noise ratio than group B1(all P<0.05),but no significant differences were found compared with group A(all P>0.05).Subjective scores were significantly higher in group A[5(5,5)point]and group B2[5(5,5)point]than in group B1[4(3,4)point](Z=-4.790,-4.564,both P<0.001),with no significant difference between groups A and B2(Z=-1.076,P=0.163).Group B reduced iodine intake and injection rate by 40%compared with group A(iodine intake:11.1 g vs.18.5 g;injection rate:3.0 ml/s vs.5.0 ml/s)and achieved a 30%reduction in effective radiation dose[(1.02±0.95)mSv vs.(1.44±1.66)mSv,t=12.217,P<0.001].Conclusion For patients with body mass index<28 kg/m2,CE-Boost combined with 100 kV tube voltage,30 ml iodinated contrast agent and 3.0 ml/s injection rate in head and neck CTA significantly reduces radiation dose,iodine load and injection rate while maintaining image quality.

Objective To evaluate the diagnostic value of black blood computed tomography(BBCT)in vulnerable plaques at the carotid bifurcation.Methods The imaging data of 73 patients with suspected carotid atherosclerosis were retrospectively analyzed.The signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of conventional computed tomography angiography(CTA)ima-ges and BBCT images were compared by paired sample t-test.The 5-level scoring method was applied to evaluate the image quality subjectively,and the Friedman test was used to compare the differences in the subjective evaluation of image quality among the groups.Taking high-resolution magnetic resonance vessel wall imaging(HRMR-VWI)as the gold standard,the diagnostic value between BBCT and conventional CTA was compared,and the consistency of BBCT and HRMR-VWI in the evaluation of vulnerable plaques was calculated.Results The standard deviation(SD)value of BBCT images was lower than that of conventional three-phase CTA images,indicating better quality of BBCT images(P＜0.001).The mean CT value and CNRplaque-lumen of non-calcified plaques were higher in BBCT images than those in conventional three-phase CTA images,suggesting that BBCT had a higher contrast with sur-rounding tissues and could better display the fine structure of non-calcified plaques(P＜0.001).BBCT images achieved the highest scores in the subjective evaluation of image quality(P＜0.001).Compared with conventional CTA images,BBCT had higher sensi-tivity(88.2％vs 29.4％)and accuracy(90.9％vs 54.5％)in identifying vulnerable plaques(P＜0.001).The Kappa value between BBCT and HRMR-VWI was 0.813,showed good consistency.Conclusion The image quality of neck BBCT is superior to that of conventional CTA.BBCT has a better effect than conventional CTA in identifying vulnerable plaques at the carotid bifurcation,which is comparable to HRMR-VWI.

Objective To evaluate the diagnostic value of black blood computed tomography(BBCT)in vulnerable plaques at the carotid bifurcation.Methods The imaging data of 73 patients with suspected carotid atherosclerosis were retrospectively analyzed.The signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of conventional computed tomography angiography(CTA)ima-ges and BBCT images were compared by paired sample t-test.The 5-level scoring method was applied to evaluate the image quality subjectively,and the Friedman test was used to compare the differences in the subjective evaluation of image quality among the groups.Taking high-resolution magnetic resonance vessel wall imaging(HRMR-VWI)as the gold standard,the diagnostic value between BBCT and conventional CTA was compared,and the consistency of BBCT and HRMR-VWI in the evaluation of vulnerable plaques was calculated.Results The standard deviation(SD)value of BBCT images was lower than that of conventional three-phase CTA images,indicating better quality of BBCT images(P＜0.001).The mean CT value and CNRplaque-lumen of non-calcified plaques were higher in BBCT images than those in conventional three-phase CTA images,suggesting that BBCT had a higher contrast with sur-rounding tissues and could better display the fine structure of non-calcified plaques(P＜0.001).BBCT images achieved the highest scores in the subjective evaluation of image quality(P＜0.001).Compared with conventional CTA images,BBCT had higher sensi-tivity(88.2％vs 29.4％)and accuracy(90.9％vs 54.5％)in identifying vulnerable plaques(P＜0.001).The Kappa value between BBCT and HRMR-VWI was 0.813,showed good consistency.Conclusion The image quality of neck BBCT is superior to that of conventional CTA.BBCT has a better effect than conventional CTA in identifying vulnerable plaques at the carotid bifurcation,which is comparable to HRMR-VWI.

Objective To observe the value of augmented reality(AR)navigation system for assisting CT-guided puncture of pulmonary nodules in dog models.Methods Five healthy dogs were selected,and 4 target lung rings were implanted in each dog to build pulmonary nodule models.Deferring to crossover design,CT-guided punctures were performed with or without AR navigation 2 and 4 weeks after successful modeling,respectively,while punctures with AR navigation were regarded as AR group and the others as conventional group,respectively.The time duration of puncturing,the times of CT scanning,of needle adjustment,and the deviation distance between needle pinpoint to the center of pulmonary nodule shown on three-dimensional reconstruction were compared between groups.Results The duration time of puncture in AR group and conventional group was(13.62±5.11)min and(20.16±4.76)min,respectively.In AR group,the times of CT scanning,of needle adjustment,and the deviation distance was 2.40±0.50,2.75±0.44 and(2.94±1.92)mm,respectively,while in conventional group was 3.10±0.64,3.70±0.57 and(4.90±3.38)mm,respectively.The introduction of AR navigation was helpful to shortening the duration of puncture,reducing times of CT scanning and needle adjustment,also decreasing positioning error of needle pinpoint(all P＜0.05).In contrast,the variance of puncture sequences and dogs had no obvious effect on the results(both P＞0.05).Conclusion AR navigation system could improve accuracy and efficiency in CT-guided puncture of pulmonary nodules in dog models.

Objective To explore the image quality improvement of portal vein computed tomography venography(CTV)using CE-Boost technique with low dose and low contrast media usage.Methods A total of 50 patients with suspected portal vein disorders who underwent abdominal non-contrast and biphasic contrast-enhanced CT scans using the Canon 320-row CT machine were retrospectively selected.Images of portal venous phase(PVP)were postprocessed with CE-Boost technique.The CT values of each area,standard deviation(SD)values of the paraspinal muscles,volume CT dose index(CTDIvol),and dose length product(DLP)before and after CE-Boost were measured and recorded.The signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR),effective dose(ED)of each blood vessel before and after CE-Boost were calculated.Subjective image quality was analyzed by two senior radiologists using a five-point scale in a double-blinded method.Statistical analysis was performed using paired t-test and Wilcoxon test.Results The CT values of each area with CE-Boost images were significantly higher than those without CE-Boost images(P＜0.001).SNR and CNR of each blood vessel with CE-Boost images were significantly higher than those without CE-Boost images(P＜0.001).The subjective scores of both images were above 3 points,which met the requirements of clinical diagnosis with good consistency(Kappa=0.772,0.697).The median subjective scores of images with CE-Boost were 5(5,5),which were significantly higher than those without CE-Boost images 5(5,4),(P=0.002).CTDIvol,DLP and ED were(1.85±1.12)mGy,(94.66±44.68)mGy·cm and(1.42±0.67)mSv,respectively.Conclusion CE-Boost technique can significantly improve the image quality of portal vein CTV with low dose and low contrast media usage.

Objective To investigate a novel stroke recurrence risk prediction model,which utilized radiomics machine learning methods and specifically combined carotid computed tomography angiography(CT A)with the Essen stroke risk score(ESRS).Methods A total of 136 patients who underwent carotid CT A were analyzed retrospectively.The features of carotid plaque were extrac-ted by machine learning to construct a radiomics feature model,as well as combined with ESRS.Based on clinical outcomes at one-year follow-up,the stroke recurrence risk prediction model was constructed using the logistic regression(LR)machine learning model.To construct an effective and robust model,the dataset was divided into a training set and a validation set in a ratio of 7∶3.The performance of this model was evaluated using area under the curve(AUC)of receiver operating characteristic(ROC)curve,sensi-tivity and specificity.Results The model had strong predictive value.In the training set,AUC,sensitivity and specificity of this model were 0.903,0.796 and 0.761,respectively.In the validation set,AUC,sensitivity and specificity of this model were 0.869,0.667 and 0.850,respectively.Conclusion The stroke recurrence risk prediction model constructed based on radiomics analysis of carotid plaque characteristics in carotid CTA,in combination with the ESRS,can provide reliable predictions for stroke prognosis.

Objective:To evaluate the effectiveness of deep learning reconstruction (DLR) compared with hybrid iterative reconstruction (Hybrid IR) in improving the image quality in chest low-dose CT (LDCT).Methods:Seventy-seven patients who underwent LDCT scan for physical examination or regular follow-up in Peking Union Medical College Hospital from October 2020 to March 2021 were retrospectively included. The LDCT images were reconstructed with Hybrid IR at standard level (Hybrid IR Stand) and DLR at standard and strong level (DLR Stand and DLR Strong). Regions of interest were placed on pulmonary lobe, aorta, subscapularis muscle and axillary fat to measure the CT value and image noise. The signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated. Subjective image quality was evaluated using Likert 5-score method by two experienced radiologists. The number and features of ground-glass nodule (GGN) were also assessed. If the scores of the two radiologists were inconsistent, the score was determined by the third radiologist. The objective and subjective image evaluation were compared using the Kruskal-Wallis test, and the Bonferroni test was used for multiple comparisons within the group.Results:Among Hybrid IR Stand, DLR Stand and DLR Strong images, the CT value of pulmonary lobe, aorta, subscapularis muscle and axillary fat had no significant differences (all P>0.05), but the image noise and SNR of pulmonary lobe, aorta, subscapularis muscle and axillary fat had significant differences(all P<0.05), and the CNR of images had significant difference( P<0.05), too. The CNR of Hybrid IR Stand images, DLR stand images and DLR strong images were 0.71 (0.49, 0.88), 1.06 (0.78, 1.32) and 1.14 (0.84, 1.48), respectively. Compared with Hybrid IR images, DLR images had lower objective and subjective image noise,higher SNR and CNR (all P<0.05). The scores of DLR images were superior to Hybrid IR images in identifying lung fissures, pulmonary vessels, trachea and bronchi, lymph nodes, pleura, pericardium and GGN (all P<0.05). Conclusions:DLR significantly reduced the image noise, and DLR images were superior to Hybrid IR images in identifying GGN in chest LDCT while maintaining superior image quality at relatively low radiation dose levels. Thus DLR images can improve the safety of lung cancer screening and pulmonary nodule follow-up by CT.

Objective:To explore application value of improving quality of the low dose pancreatic CT images by using deep learning reconstruction (DLR).Methods:From August to December 2020, 68 patients who underwent contrast-enhanced pancreatic CT were prospectively collected in Peking Union Medical College Hospital. All patients were randomly divided into routine dose group (34 patients, with tube voltage of 120 kV) and low dose group (34 patients, with tube voltage of 100 kV). All patients underwent non-contrast, arterial phase, parenchymal phase and delay phase scans. The four-phase images of low dose group were reconstructed by using filtered back projection (FBP), hybrid iterative reconstruction (AIDR) and DLR which were marked with LD-FBP, LD-AIDR and LD-DLR, respectively. The four-phase images of routine dose group were reconstructed by using AIDR algorithm which were marked with RD-AIDR. The CT value, image noise (SD), signal to noise ratio (SNR) and contrast to noise ratio (CNR) of pancreas were measured. The ANOVA test was performed in comparison with objective parameters of different reconstruction algorithms, and LSD test was performed in pairwise comparison. The subjective image scores were obtained and were compared using Kruskal-Wallis test.Results:CT value, SD, SNR and CNR of non-contrast, arterial phase, parenchymal phase and delay phase had significant difference among different reconstruction images of routine dose group and low dose group (all P<0.05). The CT value of LD-FBP, LD-AIDR, and LD-DLR images were significantly higher than those of RD-AIDR images in parenchymal phase and delay phase (all P<0.05). There were statistically significant differences in each pairwise comparison of SD and SNR of four phase images (all P<0.05). There were statistically significant differences of CNR among LD-FBP, LD-DLR and RD-AIDR in four phase images (all P<0.05). The CNR of RD-AIDR was better than that of LD-FBP, and CNR of LD-DLR was better than that of RD-AIDR. DLR algorithm improved the SD, SNR and CNR of four phases of pancreatic images. The improvement of SNR was more significant after contrast enhancement, and the improvement of CNR was more significant in the non-contrast and delay phases. Subjective image scores of different reconstruction images were statistically different in four phase images (all P<0.001). Overall image scores of LD-DLR and RD-AIDR had no significant differences in four phase ( Z value of four phases were 1.00, 2.24, 0.45 and 1.34, respectively; P value of four phases were 0.317, 0.025, 0.655 and 0.180, respectively). Conclusion:The DLR technology can decrease radiation dose of pancreatic CT, improve image quality and satisfy diagnostic requirement. The DLR technology can also reduce image noise, improve the SNR and CNR in low dose contrast-enhanced pancreatic CT.

Objective:To explore the effect of deep learning reconstruction (DLR) on radiation dosage reduction and image quality of CTPA compared with hybrid iterative reconstruction (HIR).Methods:A total of 100 patients with suspected pulmonary embolism (APE) or indications for CTPA due to other pulmonary artery diseases in Peking Union Medical College Hospital from December 2020 to April 2021 were prospectively enrolled and divided into HIR group and DLR group according to block randomization, with 50 cases in each group. The patient′s gender, age and body mass index (BMI) were recorded. HIR group and DLR group underwent standard deviation (SD)=8.8 and SD=15 CTPA protocols in combination with HIR and DLR algorithm respectively. Other scanning parameters and contrast medium injection plan were the same. The effective dose (ED) and size-specific dose estimate (SSDE) were calculated. Regions of interest (ROIs) were drawn in the lumen of Grade 1-3 pulmonary arteries and bilateral paravertebral muscles. The corresponding CT and SD values were recorded to acquire signal to noise ratio (SNR) and contrast noise ratio (CNR). Based on a double-blind method, two radiologists evaluated the subjective noise, visualization of pulmonary arteries, and diagnostic confidence of the two groups by 5-point Likert scales. The inconsistent results were judged comprehensively by the third radiologist. Independent samples t-test was used to compare the demographic data, radiation dosage and quantitative image quality of the two groups. Mann-Whitney U test was used to compare the subjective noise, visualization of pulmonary arteries and diagnostic confidence between the two groups. Linear weighted Kappa coefficient was calculated to analyze the consistency of the qualitative scores between the two radiologists. Results:There were no significant differences in gender, age and BMI between the two groups ( P>0.05). The CT values of Grade1-3 pulmonary arteries and paravertebral muscle had no significant differences ( P>0.05). Compared with HIR group, the ED and SSDE in DLR group decreased by about 35% to 1.3 mSv and 4.20 mGy respectively, while the SNR (30±5) and CNR (26±5) of CTPA images were higher in DLR group than those in HIR group (23±5 and 20±5, with t=-6.60 and -5.90, respectively, both P<0.001). The subjective noise score was higher in DLR group than that in HIR group ( Z=-7.34, P<0.001). In addition, two radiologists showed excellent interobserver agreement in DLR group (Kappa=0.847, 95%CI 0.553-1.000). No significant differences were found in visualization of pulmonary arteries and diagnostic confidence between the two groups ( P>0.05). Conclusion:DLR further reduced the radiation dosage and improved the image quality of CTPA, with no detriment to diagnostic confidence. Thus DLR is worthy of clinical promotion.