Objective:To investigate the feasibility of ultra-low dose (ULD) CT pulmonary angiography (CTPA) combined with deep learning reconstruction (DLR) in the diagnosis of pulmonary embolism (PE).Methods:This cross-sectional study prospectively enrolled 100 patients with suspected PE who underwent CTPA examination in Zhongshan Hospital Fudan University, and Shanghai Geriatric Medical Center from April to July 2024, and were randomly divided into the routine dose (RD) group and ULD group according to block randomization. Effective dose (ED) were calculated. The noise index of RD group and ULD group was set to 10 and 20, respectively. Other scanning parameters and contrast agent injection protocol were the same. The CT images of RD group were reconstructed using hybrid iterative reconstruction (HIR), while ULD images were reconstructed with HIR and DLR (ULD-HIR subgroup and ULD-DLR subgroup). The image quality of the three groups of images was subjectively evaluated (overall image noise, pulmonary artery display) and objectively evaluated [signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) of the images] respectively. Finally, the diagnostic results of PE by the expert committee composed of three chief physicians were taken as the gold standard, and one physician with lower qualifications independently evaluated the diagnostic rate of PE in the three groups of images. Objective image quality parameters across the three groups were compared using ANOVA, with LSD post hoc test was used for multiple comparisons. Subjective scores among the three groups were analyzed using the Kruskal-Wallis H test, with Bonferroni corrected pairwise post hoc test was applied for multiple pairwise comparisons. Results:The ED in the RD group and ULD group were (2.7±0.5) mSv and (0.7±0.2) mSv, respectively, and the differences were statistically significant ( t=26.42, P<0.001). The overall differences in CT values of pulmonary arteries at all levels in the images of the RD group, the ULD-HIR subgroup, and the ULD-DLR subgroup were not statistically significant ( P>0.05).The RD group, ULD-HIR subgroup and ULD-DLR subgroup overall differences in SNR and CNR at all levels pulmonary arteries were statistically significant ( P<0.001), in which except for the differences in CNR and SNR values of the left pulmonary arterial trunk in the RD group and the ULD-HIR subgroup, and SNR values of basal segment pulmonary artery of the lower lobe of the left lung, which were not statistically significant ( P>0.05), the differences of the rest of the indexes in the pairwise comparisons between the groups were statistically significant ( P<0.05). The overall differences in the subjective scores of image pulmonary vascular display and image noise in the RD group, ULD-HIR subgroup and ULD-DLR subgroup were statistically significant ( P<0.001), except that the differences in the subjective scores of image pulmonary vascular display in the ULD-DLR subgroup were not statistically significant when compared with that of the RD group ( P>0.05) and that of the rest of the metrics in the between-groups two-by-two comparisons were all statistically significant ( P<0.05). The difference in diagnostic rates of PE in the pulmonary artery trunk, lobe and segmental levels in the images of the RD group, ULD-HIR subgroup and ULD-DLR subgroup was not statistically significant ( P>0.05). Conclusions:DLR can significantly reduce the radiation dose of CTPA examination. Even at ultra-low radiation dose, its image quality is still better than HIR reconstruction at conventional doses and preserve diagnostic accuracy of PE at the lobe level and segment level.

Objective To investigate the value of flexible subtraction CE-Boost technique combined with low dosage contrast agents for CT pulmonary angiography(CTPA).Methods A total of 68 patients who would undergo CTPA examination due to suspected pulmonary embolism(PE)were prospectively enrolled and randomly divided into study group(n=34)and control group(n=34)using block randomization method.After injecting 25 ml contrast agents at a flow rate of 2.5 ml/s in study group or 50 ml contrast agents at a flow rate of 3.5 ml/s in control group,CTPA scanning were performed with identical parameters.For images in study group,hybrid iterative reconstruction was performed,followed by flexible subtraction CE-Boost post-processing to obtain CE-Boost CTPA.For images in control group,conventional CTPA was obtained with hybrid iterative reconstruction.Subjective and objective evaluations of image quality were compared between groups.Taken the final clinical diagnosis as standard,the accuracy rate of diagnosing PE were compared between groups.Results There were 7 cases of pulmonary artery main trunk PE and 15 cases of pulmonary lobe-level PE in study group,while in control group there were 8 cases and 17 cases.No statistical difference of subjective scores of CTPA was found between groups(P＞0.05).CT values of the main pulmonary artery,bilateral pulmonary artery trunks and lower lobes of both lungs,signal-to-noise ratio or contrast-to-noise ratio in CTPA were not significantly different between groups(all P＞0.05),while no significant difference of the accuracy rate of CTPA for diagnosing PE of pulmonary artery main trunk(100％[7/7]vs.100％[8/8])nor pulmonary lobe-level PE(86.67％[13/15]vs.88.24％[15/17])was detected between groups(all P＞0.05).Conclusion Flexible subtraction CE-Boost technique combined with low dosage contrast agents for CTPA could reduce contrast agent dosage without affecting image quality.

Objective:To investigate the feasibility of ultra-low dose (ULD) CT pulmonary angiography (CTPA) combined with deep learning reconstruction (DLR) in the diagnosis of pulmonary embolism (PE).Methods:This cross-sectional study prospectively enrolled 100 patients with suspected PE who underwent CTPA examination in Zhongshan Hospital Fudan University, and Shanghai Geriatric Medical Center from April to July 2024, and were randomly divided into the routine dose (RD) group and ULD group according to block randomization. Effective dose (ED) were calculated. The noise index of RD group and ULD group was set to 10 and 20, respectively. Other scanning parameters and contrast agent injection protocol were the same. The CT images of RD group were reconstructed using hybrid iterative reconstruction (HIR), while ULD images were reconstructed with HIR and DLR (ULD-HIR subgroup and ULD-DLR subgroup). The image quality of the three groups of images was subjectively evaluated (overall image noise, pulmonary artery display) and objectively evaluated [signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) of the images] respectively. Finally, the diagnostic results of PE by the expert committee composed of three chief physicians were taken as the gold standard, and one physician with lower qualifications independently evaluated the diagnostic rate of PE in the three groups of images. Objective image quality parameters across the three groups were compared using ANOVA, with LSD post hoc test was used for multiple comparisons. Subjective scores among the three groups were analyzed using the Kruskal-Wallis H test, with Bonferroni corrected pairwise post hoc test was applied for multiple pairwise comparisons. Results:The ED in the RD group and ULD group were (2.7±0.5) mSv and (0.7±0.2) mSv, respectively, and the differences were statistically significant ( t=26.42, P<0.001). The overall differences in CT values of pulmonary arteries at all levels in the images of the RD group, the ULD-HIR subgroup, and the ULD-DLR subgroup were not statistically significant ( P>0.05).The RD group, ULD-HIR subgroup and ULD-DLR subgroup overall differences in SNR and CNR at all levels pulmonary arteries were statistically significant ( P<0.001), in which except for the differences in CNR and SNR values of the left pulmonary arterial trunk in the RD group and the ULD-HIR subgroup, and SNR values of basal segment pulmonary artery of the lower lobe of the left lung, which were not statistically significant ( P>0.05), the differences of the rest of the indexes in the pairwise comparisons between the groups were statistically significant ( P<0.05). The overall differences in the subjective scores of image pulmonary vascular display and image noise in the RD group, ULD-HIR subgroup and ULD-DLR subgroup were statistically significant ( P<0.001), except that the differences in the subjective scores of image pulmonary vascular display in the ULD-DLR subgroup were not statistically significant when compared with that of the RD group ( P>0.05) and that of the rest of the metrics in the between-groups two-by-two comparisons were all statistically significant ( P<0.05). The difference in diagnostic rates of PE in the pulmonary artery trunk, lobe and segmental levels in the images of the RD group, ULD-HIR subgroup and ULD-DLR subgroup was not statistically significant ( P>0.05). Conclusions:DLR can significantly reduce the radiation dose of CTPA examination. Even at ultra-low radiation dose, its image quality is still better than HIR reconstruction at conventional doses and preserve diagnostic accuracy of PE at the lobe level and segment level.

Objective To investigate the value of flexible subtraction CE-Boost technique combined with low dosage contrast agents for CT pulmonary angiography(CTPA).Methods A total of 68 patients who would undergo CTPA examination due to suspected pulmonary embolism(PE)were prospectively enrolled and randomly divided into study group(n=34)and control group(n=34)using block randomization method.After injecting 25 ml contrast agents at a flow rate of 2.5 ml/s in study group or 50 ml contrast agents at a flow rate of 3.5 ml/s in control group,CTPA scanning were performed with identical parameters.For images in study group,hybrid iterative reconstruction was performed,followed by flexible subtraction CE-Boost post-processing to obtain CE-Boost CTPA.For images in control group,conventional CTPA was obtained with hybrid iterative reconstruction.Subjective and objective evaluations of image quality were compared between groups.Taken the final clinical diagnosis as standard,the accuracy rate of diagnosing PE were compared between groups.Results There were 7 cases of pulmonary artery main trunk PE and 15 cases of pulmonary lobe-level PE in study group,while in control group there were 8 cases and 17 cases.No statistical difference of subjective scores of CTPA was found between groups(P＞0.05).CT values of the main pulmonary artery,bilateral pulmonary artery trunks and lower lobes of both lungs,signal-to-noise ratio or contrast-to-noise ratio in CTPA were not significantly different between groups(all P＞0.05),while no significant difference of the accuracy rate of CTPA for diagnosing PE of pulmonary artery main trunk(100％[7/7]vs.100％[8/8])nor pulmonary lobe-level PE(86.67％[13/15]vs.88.24％[15/17])was detected between groups(all P＞0.05).Conclusion Flexible subtraction CE-Boost technique combined with low dosage contrast agents for CTPA could reduce contrast agent dosage without affecting image quality.

Mice ; Animals ; Spiral Ganglion/physiology* ; Cochlea/physiology* ; Neurons

Objective To compare the differences of the spectral CT parameters between benign and malignant mediastina lymph nodes and to investigate the value of spectral imaging in the differential diagnosis. Methods According to the follow-up and pathology results, a total of 73 patients were enrolled in this study. One experienced radiologist determined the locations of lymph nodes on CT images corresponding to the surgical pathological ones. A total of 47 malignant nodes and 65 benign nodes were found. The longest and shortest diameters of lymph nodes in mediastina window were measured .The vHU, IC, WC, Zef and the CT values of normal lung, normal muscle and lymph nodes at 40, 70 and 140 keV were measured. The indices were compared between the benign nodes and malignant nodes by independent-samples t test. The Spectral HU curves were drawn. Results The long and short diameter of malignant lymph nodes were (28.8 ± 10.5),(20.3 ± 9.1)cm , while they were were (14.0 ± 4.6),(7.5 ± 1.8)cm for benign lymph nodes. Malignant nodes were significantly larger than benign nodes (t= 6.54, 7.13, respectively, P<0.05), The differences of the CT values at 40, 70 and 140 keV and the vHU, IC, WC, Zef for the normal lung, normal muscle and lymph nodes between the two groups had no statistical significance (P>0.05). The two groups showed similar spectral HU curve slopes (1.86 values 1.73). Conclusion Spectral imaging may not be helpful in the differential diagnosis of malignant and benign lymph nodes.