Objective To develop an automated bone mineral density(BMD)assessment model based on proximal femur images from abdomen-pelvic CT scans and to analyze its application value in opportunistic osteoporosis(OP)screening.Methods A retrospective selection was conducted on 351 patients who underwent abdomen-pelvic plain CT examination.The patients were randomly divided into training set(n=245)and test set(n=106)in a ratio of 7∶3.All images were transferred to a quantitative computed tomography(QCT)post-processing workstation to measure the BMD of the left proximal femur.According to the QCT BMD T-score,the patients were divided into osteoporosis(T-score-2.5),osteopenia(-2.5＜T-score＜-1)and normal bone density(T-score≥-1).The left proximal femur was dissected using an automatic segmentation model,and two three-class BMD assessment radiomics models were constructed using random forest(RF)and logistic regression(LR)classifiers,respectively.The receiver operating characteristic(ROC)curves were generated,and the area under the curve(AUC),sensitivity,specificity and other metrics were calculated to evaluate the diagnostic performance of the two models.The DeLong test was used to compare differences between the models.Results In the test set,the AUC of the RF and LR models for identifying osteoporosis were 0.953 and 0.954,respectively.The AUC for identifying osteopenia were 0.894 and 0.870,and the AUC for identifying normal bone density were 0.975 and 0.982,respectively.The comparison of model performance showed no statistically significant differences between the RF and LR models in identifying the three bone states in both the training and test sets(P＞0.05).Conclusion Both the RF and LR radiomics models,constructed based on abdomen-pelvic plain CT scans,can be used for opportunistic BMD screening with high diagnostic efficiency.

Purpose To explore the application value of auto-prescription technique in CT portal venography and liver volume measurement.Materials and Methods A total of 180 patients who underwent contrast-enhanced abdominal CT in the First Affiliated Hospital of Dalian Medical University from April to November 2022 were prospectively collected and randomly divided into two groups,with 90 cases in each group.Group A(experimental group)was scanned with auto-prescription technique.Group B(conventional group)was scanned with 120 kVp,and the other imaging parameters kept the same as group A.In group A,the correlation between body mass index and tube voltage(kVp)recommended by auto-prescription technique was analyzed.The following values were compared between group A and group B,including the volume CT dose index,dose length product,CT value of portal vein and liver,standard deviation,contrast-to-noise ratio(CNR),image quality and subjective score of automatic segmentation.The liver volumes of group A and B were measured by Liver Segmentation software.The volumes measured by automatic segmentation software(Vsoft)were recorded,and then were compared with those segmented manually(gold standard)(Vstnd).Results Compared with group B,the volume CT dose index and dose length product in group A decreased by 22%and 25%(t=-4.654,-5.403,both P<0.05),respectively.The CT value and CNR of portal vein and liver in group A were higher than those in group B(t=4.857-6.011,all P<0.05).There was no significant difference in standard deviation,Vstnd and Vsoft between group A and group B(P>0.05).The consistency of subjective scores between the two observers was good(ICC=0.773-0.856,all P<0.05).The subjective scores of two-dimensional and three-dimensional images,as well as the automatic software segmentation scores in group A were higher than those in group B(Z=897.500,1 287.500,912.721,all P<0.05).The recommended kVp value in group A was positively correlated with body mass index(r=0.674,P<0.001).Conclusion The application of auto-prescription technique in CT portal venography can ensure the image quality,measure the liver volume accurately,and reduce the patient's radiation dose individually.

Objective To explore the feasibility of constructing a three-classification bone status screening radiomics model on chest CT images.Methods A total of 371 patients who underwent both chest and abdominal plain CT examinations were retrospec-tively selected and randomly divided into training set(296 cases)and test set(75 cases)in a ratio of 8︰2.Additionally,110 patients were included as external validation set using the same criteria.The 120 kVp abdominal images were transmitted to a quantitative compu-ted tomography(QCT)post-processing workstation to measure the bone mineral density(BMD)of the L1-L2 vertebral bodies.Patients were classified into osteoporosis(OP)group(BMD<80 mg/cm3),osteopenia group(80 mg/cm3≤BMD≤120 mg/cm3)and normal bone mass group(BMD>120 mg/cm3)based on QCT BMD results.The automatic segmentation model was used to segment T10-T12 vertebral trabecular bone on chest CT images and the radiomics models based on random forest(RF)and logistic regres-sion(LR)was established to evaluate BMD,enabling it to simultaneously distinguish OP,osteopenia,and normal bone mass.The diag-nostic performance of the two models were evaluated using metrics such as the area under the curve(AUC),sensitivity and specificity.The DeLong test was used to compare the differences between the two models.Results In the test set,the AUC for differentiating normal bone mass were 0.948 and 0.877 for the RF and LR models,respectively;the AUC for differentiating OP were 0.942 and 0.836,respectively;and the AUC for differentiating osteopenia were 0.871 and 0.688,respectively.The performance comparison results of the models showed that there was no statistically significant difference in AUC(0.966 vs 0.907,P>0.05)between RF model and LR model in the external validation set for distinguishing OP,while there was a statistically significant difference in AUC for distinguishing osteopenia(0.895 vs 0.749,P=0.009)and normal bone mass(0.975 vs 0.906,P=0.023).The RF model performance was superior to the LR model.Conclusion The radiomics model developed based on chest plain CT can be used for opportunistic OP screening with good diagnostic efficacy,and the the model based on the RF classifier outperforms the LR model.

Objective To explore the value of contrast agent injection protocol based on individualized iodine delivery rate(IDR)applicated in enhanced spectral CT scanning of colorectal cancer.Methods Totally 131 colorectal cancer patients were prospectively collected and randomly divided into conventional group(group A,n=64,contrast agents were injected with routine method)and individualized group(group B,n=67,contrast agents were injected with individualized IDR method).Whole abdominal energy spectrum CT scanning was performed,and 70 keV images at arterial and venous phases(A70 keV)of group A and 40-70 keV images(interval 10 keV)at arterial and venous phases(B40-70 keV)of group B were reconstructed,and iodine-based material maps were reconstructed.Subjective and objective evaluation on quality of enhanced images were performed,lesions'normalized iodine concentration(NIC)were calculated,and the above indexes were compared between groups.Results Iodine intake in group B was lower than that in group A(P＜0.001).The subjective scores of B60 keV images at both arterial and venous phases were the highest,which were not different from those of A70 keV images(both P＞0.05).CT values,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of superior mesenteric artery(SMA)and abdominal aorta on arterial B40-60 keV images were higher than those in arterial A70 keV images(all P＜0.05).CT values,SNR and CNR of superior mesenteric vein(SMV)on venous B40-50 keV,as well as CT values and CNR of SMV on venous B60 keV images were all higher than those on venous A70 keV images(all P＜0.05).No significant difference of lesions'NIC in arterial and venous phases was detected between groups(both P＞0.05).Conclusion Injection of contrast agents based on IDR combined with 60 keV single energy image for enhanced energy spectrum CT scanning of colorectal cancer could reduce the amount of contrast agents while do not affect imaging quality.

Purpose To explore the application value of auto-prescription technique in CT portal venography and liver volume measurement.Materials and Methods A total of 180 patients who underwent contrast-enhanced abdominal CT in the First Affiliated Hospital of Dalian Medical University from April to November 2022 were prospectively collected and randomly divided into two groups,with 90 cases in each group.Group A(experimental group)was scanned with auto-prescription technique.Group B(conventional group)was scanned with 120 kVp,and the other imaging parameters kept the same as group A.In group A,the correlation between body mass index and tube voltage(kVp)recommended by auto-prescription technique was analyzed.The following values were compared between group A and group B,including the volume CT dose index,dose length product,CT value of portal vein and liver,standard deviation,contrast-to-noise ratio(CNR),image quality and subjective score of automatic segmentation.The liver volumes of group A and B were measured by Liver Segmentation software.The volumes measured by automatic segmentation software(Vsoft)were recorded,and then were compared with those segmented manually(gold standard)(Vstnd).Results Compared with group B,the volume CT dose index and dose length product in group A decreased by 22%and 25%(t=-4.654,-5.403,both P<0.05),respectively.The CT value and CNR of portal vein and liver in group A were higher than those in group B(t=4.857-6.011,all P<0.05).There was no significant difference in standard deviation,Vstnd and Vsoft between group A and group B(P>0.05).The consistency of subjective scores between the two observers was good(ICC=0.773-0.856,all P<0.05).The subjective scores of two-dimensional and three-dimensional images,as well as the automatic software segmentation scores in group A were higher than those in group B(Z=897.500,1 287.500,912.721,all P<0.05).The recommended kVp value in group A was positively correlated with body mass index(r=0.674,P<0.001).Conclusion The application of auto-prescription technique in CT portal venography can ensure the image quality,measure the liver volume accurately,and reduce the patient's radiation dose individually.

Objective To explore the feasibility of spectral CT material decomposition technique Ca(Iodine)for opportunistic osteoporo-sis screening in enhanced scanning.Methods A total of 314 patients who underwent abdominal enhancement were selected.They were divided into group A and group B according to gender,and the groups were divided into three subgroups according to age(18-45 years,46-60 years,>60 years).The bone mineral density(BMD)values of L1-L3 vertebral were measured in the unenhanced images using quan-titative computed tomography(QCT)software,and Ca(Iodine)values were measured on three enhancement phases Ca(Iodine)based substance images.Pearson correlation analysis was performed between iodine intake and Ca(Iodine)values in three enhancement phases,Ca(Iodine)values and quantitative computed tomography bone mineral density(BMDQCT),and the diagnostic efficacy was analyzed.Results There was no significant difference in the Ca(Iodine)values of L1-L3 vertebral in three enhancement phases(F=0.001-0.018,P>0.05);there was no correlation between the Ca(Iodine)values of L1-L3 vertebral in three enhancement phases and iodine intake(r=0.073-0.105,P>0.05).Six groups of measured Ca(Iodine)values and BMDQCT both had a strong positive correlation(r=0.901-0.954,P<0.05).The Ca(Iodine)cutoff values for the diagnosis of osteoporosis and osteopenia were 830.41(2 mg/cm3)and 849.32(2 mg/cm3)respectively,with corresponding area under the curve(AUC)of 0.969[95%confidence interval(CI)0.943-0.985]and 0.973(95%CI 0.944-0.989),respectively.There were statistically significant differences in Ca(Iodine)values and BMDQCT in the>60 years age group between different genders(t=3.081-3.091,P<0.05).Conclusion Spectral CT material decomposition technique can be used for oppor-tunistic osteoporosis screening in enhanced scanning,with good diagnostic performance,which provides a new perspective for the clin-ical diagnosis of osteoporosis.

Objective To explore the feasibility of constructing a three-classification bone status screening radiomics model on chest CT images.Methods A total of 371 patients who underwent both chest and abdominal plain CT examinations were retrospec-tively selected and randomly divided into training set(296 cases)and test set(75 cases)in a ratio of 8︰2.Additionally,110 patients were included as external validation set using the same criteria.The 120 kVp abdominal images were transmitted to a quantitative compu-ted tomography(QCT)post-processing workstation to measure the bone mineral density(BMD)of the L1-L2 vertebral bodies.Patients were classified into osteoporosis(OP)group(BMD<80 mg/cm3),osteopenia group(80 mg/cm3≤BMD≤120 mg/cm3)and normal bone mass group(BMD>120 mg/cm3)based on QCT BMD results.The automatic segmentation model was used to segment T10-T12 vertebral trabecular bone on chest CT images and the radiomics models based on random forest(RF)and logistic regres-sion(LR)was established to evaluate BMD,enabling it to simultaneously distinguish OP,osteopenia,and normal bone mass.The diag-nostic performance of the two models were evaluated using metrics such as the area under the curve(AUC),sensitivity and specificity.The DeLong test was used to compare the differences between the two models.Results In the test set,the AUC for differentiating normal bone mass were 0.948 and 0.877 for the RF and LR models,respectively;the AUC for differentiating OP were 0.942 and 0.836,respectively;and the AUC for differentiating osteopenia were 0.871 and 0.688,respectively.The performance comparison results of the models showed that there was no statistically significant difference in AUC(0.966 vs 0.907,P>0.05)between RF model and LR model in the external validation set for distinguishing OP,while there was a statistically significant difference in AUC for distinguishing osteopenia(0.895 vs 0.749,P=0.009)and normal bone mass(0.975 vs 0.906,P=0.023).The RF model performance was superior to the LR model.Conclusion The radiomics model developed based on chest plain CT can be used for opportunistic OP screening with good diagnostic efficacy,and the the model based on the RF classifier outperforms the LR model.

Objective To develop an automated bone mineral density(BMD)assessment model based on proximal femur images from abdomen-pelvic CT scans and to analyze its application value in opportunistic osteoporosis(OP)screening.Methods A retrospective selection was conducted on 351 patients who underwent abdomen-pelvic plain CT examination.The patients were randomly divided into training set(n=245)and test set(n=106)in a ratio of 7∶3.All images were transferred to a quantitative computed tomography(QCT)post-processing workstation to measure the BMD of the left proximal femur.According to the QCT BMD T-score,the patients were divided into osteoporosis(T-score-2.5),osteopenia(-2.5＜T-score＜-1)and normal bone density(T-score≥-1).The left proximal femur was dissected using an automatic segmentation model,and two three-class BMD assessment radiomics models were constructed using random forest(RF)and logistic regression(LR)classifiers,respectively.The receiver operating characteristic(ROC)curves were generated,and the area under the curve(AUC),sensitivity,specificity and other metrics were calculated to evaluate the diagnostic performance of the two models.The DeLong test was used to compare differences between the models.Results In the test set,the AUC of the RF and LR models for identifying osteoporosis were 0.953 and 0.954,respectively.The AUC for identifying osteopenia were 0.894 and 0.870,and the AUC for identifying normal bone density were 0.975 and 0.982,respectively.The comparison of model performance showed no statistically significant differences between the RF and LR models in identifying the three bone states in both the training and test sets(P＞0.05).Conclusion Both the RF and LR radiomics models,constructed based on abdomen-pelvic plain CT scans,can be used for opportunistic BMD screening with high diagnostic efficiency.

Objective To explore the feasibility of spectral CT material decomposition technique Ca(Iodine)for opportunistic osteoporo-sis screening in enhanced scanning.Methods A total of 314 patients who underwent abdominal enhancement were selected.They were divided into group A and group B according to gender,and the groups were divided into three subgroups according to age(18-45 years,46-60 years,>60 years).The bone mineral density(BMD)values of L1-L3 vertebral were measured in the unenhanced images using quan-titative computed tomography(QCT)software,and Ca(Iodine)values were measured on three enhancement phases Ca(Iodine)based substance images.Pearson correlation analysis was performed between iodine intake and Ca(Iodine)values in three enhancement phases,Ca(Iodine)values and quantitative computed tomography bone mineral density(BMDQCT),and the diagnostic efficacy was analyzed.Results There was no significant difference in the Ca(Iodine)values of L1-L3 vertebral in three enhancement phases(F=0.001-0.018,P>0.05);there was no correlation between the Ca(Iodine)values of L1-L3 vertebral in three enhancement phases and iodine intake(r=0.073-0.105,P>0.05).Six groups of measured Ca(Iodine)values and BMDQCT both had a strong positive correlation(r=0.901-0.954,P<0.05).The Ca(Iodine)cutoff values for the diagnosis of osteoporosis and osteopenia were 830.41(2 mg/cm3)and 849.32(2 mg/cm3)respectively,with corresponding area under the curve(AUC)of 0.969[95%confidence interval(CI)0.943-0.985]and 0.973(95%CI 0.944-0.989),respectively.There were statistically significant differences in Ca(Iodine)values and BMDQCT in the>60 years age group between different genders(t=3.081-3.091,P<0.05).Conclusion Spectral CT material decomposition technique can be used for oppor-tunistic osteoporosis screening in enhanced scanning,with good diagnostic performance,which provides a new perspective for the clin-ical diagnosis of osteoporosis.

Objective To explore the value of contrast agent injection protocol based on individualized iodine delivery rate(IDR)applicated in enhanced spectral CT scanning of colorectal cancer.Methods Totally 131 colorectal cancer patients were prospectively collected and randomly divided into conventional group(group A,n=64,contrast agents were injected with routine method)and individualized group(group B,n=67,contrast agents were injected with individualized IDR method).Whole abdominal energy spectrum CT scanning was performed,and 70 keV images at arterial and venous phases(A70 keV)of group A and 40-70 keV images(interval 10 keV)at arterial and venous phases(B40-70 keV)of group B were reconstructed,and iodine-based material maps were reconstructed.Subjective and objective evaluation on quality of enhanced images were performed,lesions'normalized iodine concentration(NIC)were calculated,and the above indexes were compared between groups.Results Iodine intake in group B was lower than that in group A(P＜0.001).The subjective scores of B60 keV images at both arterial and venous phases were the highest,which were not different from those of A70 keV images(both P＞0.05).CT values,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of superior mesenteric artery(SMA)and abdominal aorta on arterial B40-60 keV images were higher than those in arterial A70 keV images(all P＜0.05).CT values,SNR and CNR of superior mesenteric vein(SMV)on venous B40-50 keV,as well as CT values and CNR of SMV on venous B60 keV images were all higher than those on venous A70 keV images(all P＜0.05).No significant difference of lesions'NIC in arterial and venous phases was detected between groups(both P＞0.05).Conclusion Injection of contrast agents based on IDR combined with 60 keV single energy image for enhanced energy spectrum CT scanning of colorectal cancer could reduce the amount of contrast agents while do not affect imaging quality.