Objective:To investigate the value of diffusion kurtosis imaging (DKI) and 18F-prostate specific membrane antigen (PSMA)-1007 in the differential diagnosis of prostate cancer (PCa) and benign prostatic hyperplasia (BPH) by using PET/MR imaging. Methods:From June 2019 to December 2022, a retrospective analysis was conducted on 134 patients ((65.5±10.0) years) with prostate diseases who underwent 18F-PSMA-1007 PET/MR whole-body examination at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, with the prostate specific antigen (PSA) level continuously rising to >4μg/L within 1 month and not yet receiving treatment. Patients were divided into 2 groups (PSA<10μg/L and PSA≥10μg/L). The PET/MR examination included high b-value diffusion imaging, and the ROI was delineated based on the prostate diffusion weighted imaging (DWI) high-signal area and apparent diffusion coefficient (ADC) low-signal area by the professional radiology physician. The SUV max, mean kurtosis (MK), and mean diffusivity (MD) were obtained. Spearman rank correlation analysis was performed, and ROC curve was used to analyze the diagnostic efficacy. Results:Of 134 patients, 72 were with PSA<10μg/L and 62 were with PSA≥10μg/L. There were 68 patients who obtained biopsy results, including 37 cases of BPH and 31 cases of PCa. In PSA<10μg/L group, there were no significant correlations between MK and SUV max, MK and PSA ( rs values: 0.22, 0.06, P values: 0.065, 0.603). In the PSA≥10μg/L group, there were positive correlations between MK and SUV max, MK and PSA ( rs values: 0.52, 0.40, P values: 0.008, 0.005). In the PSA<10μg/L group, SUV max, MK, and MD showed no diagnostic value (AUCs: 0.44-0.67, all P>0.05), while the AUC for combined diagnosis using these three parameters was 0.78( P=0.008). In the PSA≥10μg/L group, the AUCs of SUV max, MK, and MD were 0.81( P=0.001), 0.84( P<0.001) and 0.72( P=0.023) respectively, and the AUC for combined diagnosis using these three parameters was 0.91( P<0.001). Conclusion:The combination of MK, MD and SUV max improves the diagnostic efficacy of PCa in PET/MR examination.

Objective:To investigate the value of diffusion kurtosis imaging (DKI) and 18F-prostate specific membrane antigen (PSMA)-1007 in the differential diagnosis of prostate cancer (PCa) and benign prostatic hyperplasia (BPH) by using PET/MR imaging. Methods:From June 2019 to December 2022, a retrospective analysis was conducted on 134 patients ((65.5±10.0) years) with prostate diseases who underwent 18F-PSMA-1007 PET/MR whole-body examination at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, with the prostate specific antigen (PSA) level continuously rising to >4μg/L within 1 month and not yet receiving treatment. Patients were divided into 2 groups (PSA<10μg/L and PSA≥10μg/L). The PET/MR examination included high b-value diffusion imaging, and the ROI was delineated based on the prostate diffusion weighted imaging (DWI) high-signal area and apparent diffusion coefficient (ADC) low-signal area by the professional radiology physician. The SUV max, mean kurtosis (MK), and mean diffusivity (MD) were obtained. Spearman rank correlation analysis was performed, and ROC curve was used to analyze the diagnostic efficacy. Results:Of 134 patients, 72 were with PSA<10μg/L and 62 were with PSA≥10μg/L. There were 68 patients who obtained biopsy results, including 37 cases of BPH and 31 cases of PCa. In PSA<10μg/L group, there were no significant correlations between MK and SUV max, MK and PSA ( rs values: 0.22, 0.06, P values: 0.065, 0.603). In the PSA≥10μg/L group, there were positive correlations between MK and SUV max, MK and PSA ( rs values: 0.52, 0.40, P values: 0.008, 0.005). In the PSA<10μg/L group, SUV max, MK, and MD showed no diagnostic value (AUCs: 0.44-0.67, all P>0.05), while the AUC for combined diagnosis using these three parameters was 0.78( P=0.008). In the PSA≥10μg/L group, the AUCs of SUV max, MK, and MD were 0.81( P=0.001), 0.84( P<0.001) and 0.72( P=0.023) respectively, and the AUC for combined diagnosis using these three parameters was 0.91( P<0.001). Conclusion:The combination of MK, MD and SUV max improves the diagnostic efficacy of PCa in PET/MR examination.

[Objective]To explore the diagnostic value of conventional ultrasound combined with shear wave elastography (SWE) for sarcopenia in patients with chronic kidney disease (CKD).[Methods]The study included 94 CKD patients (34 with sarcopenia and 60 without). All patient underwent the Simplified Assessment Rating Questionnaire (SARC-CalF),Mini Nutritional Assessment (MNA),Short Physical Performance Battery (SPPB),grip strength test,bioelectrical impedance analysis (BIA),conventional muscle ultrasound and SWE of the thighs. We then compared the differences in indicators between the sarcopenia group and non-sarcopenia group,used Spearman correlation analysis to assess the relationship between the two examinations (conventional ultrasound and SWE) and other clinical indicators,identified the diagnostic markers for sarcopenia,created receiver operating characteristic (ROC) curves,calculated the area under the curve (AUC) and determined the diagnostic performance of conventional ultrasound,SWE and their combination. Binary logistic regression was used to analyze the influencing factors of sarcopenia in CKD patients and a combined diagnosis model was established.[Results]The sarcopenia group showed lower upper arm circumference,calf circumference,6-meter walking speed and handgrip strength than non-sarcopenia group,and the differences were statistically significant (P<0.05). The sarcopenia group exhibited lower SARC-CalF and SPBB scores,as well as more compromised nutritional status. Statistically significant differences were observed in the ultrasound parameters between the two groups,including thickness of the subcutaneous fat and rectus femoris,combined thickness of the rectus femoris and vastus intermedius,rectus femoris cross-sectional area,elastic modulus of the rectus femoris and vastus medialis (all P<0.05). The muscle mass index had a moderate positive correlation with muscle thickness and cross-sectional area of the rectus femoris (0.3

Objective·To analyze the imaging characteristics and diagnostic value of 18F-fluorodeoxyglucose positron emission tomography-computed tomography(18F-FDG PET/CT)in mantle cell lymphoma(MCL)and explore its application to distinguishing between classic and aggressive variants of MCL.Methods·A retrospective analysis was conducted on the 18F-FDG PET/CT images and clinical data of 116 pathologically confirmed,newly diagnosed MCL patients.The imaging features of intra-and extra-nodal lesions were summarized.The accuracy of 18F-FDG PET/CT in diagnosing bone marrow and gastrointestinal involvement in MCL was evaluated.Furthermore,differences in 18F-FDG PET/CT findings and clinical characteristics between the classic and aggressive variants of MCL were analyzed.Results·Among the 116 patients,100.0%showed positive findings on 18F-FDG PET/CT,with 99.1%exhibiting abnormal lymph nodes and 85.3%having extra-nodal involvement.The most common extra-nodal sites were the spleen,Waldeyer's ring,bone marrow,and gastrointestinal tract.Compared with bone marrow aspiration results,the sensitivity,specificity,and accuracy of 18F-FDG PET/CT for detecting bone marrow involvement in MCL were 43.4%,91.5%,and 66.0%,respectively.When compared with endoscopic biopsy results,the sensitivity of 18F-FDG PET/CT for detecting gastric and intestinal involvement was 100.0%and 94.1%,respectively,with specificity of 75.0%and 100.0%,and accuracy of 92.9%and 94.7%,respectively.There were significant differences in the highest maximum standardized uptake value(SUVmax)and Ki-67 index between the classic and aggressive variants of MCL,with SUVmax positively correlated with Ki-67 index.By using SUVmax>10.4 as the diagnostic threshold,the sensitivity and specificity for differentiating between the classic and aggressive variants of MCL were 73.9%and 77.4%,respectively,with an AUC value of 0.797.Conclusion·18F-FDG PET/CT demonstrates a high detection rate for both intra-and extra-nodal lesions in MCL patients.It exhibits high specificity in diagnosing bone marrow involvement and high sensitivity and specificity in diagnosing gastrointestinal involvement,providing reliable non-invasive diagnostic information for MCL bone marrow and gastrointestinal involvement.However,it is not a substitute for pathological examination.Additionally,the positive correlation between SUVmax and Ki-67 index allows SUVmax to effectively differentiate between the classic and aggressive variants of MCL,with a higher SUVmax(>10.4)indicating a higher likelihood of the aggressive variant.These findings have clinical implications for treatment planning and prognosis assessment.

Objective·To analyze the imaging characteristics and diagnostic value of 18F-fluorodeoxyglucose positron emission tomography-computed tomography(18F-FDG PET/CT)in mantle cell lymphoma(MCL)and explore its application to distinguishing between classic and aggressive variants of MCL.Methods·A retrospective analysis was conducted on the 18F-FDG PET/CT images and clinical data of 116 pathologically confirmed,newly diagnosed MCL patients.The imaging features of intra-and extra-nodal lesions were summarized.The accuracy of 18F-FDG PET/CT in diagnosing bone marrow and gastrointestinal involvement in MCL was evaluated.Furthermore,differences in 18F-FDG PET/CT findings and clinical characteristics between the classic and aggressive variants of MCL were analyzed.Results·Among the 116 patients,100.0%showed positive findings on 18F-FDG PET/CT,with 99.1%exhibiting abnormal lymph nodes and 85.3%having extra-nodal involvement.The most common extra-nodal sites were the spleen,Waldeyer's ring,bone marrow,and gastrointestinal tract.Compared with bone marrow aspiration results,the sensitivity,specificity,and accuracy of 18F-FDG PET/CT for detecting bone marrow involvement in MCL were 43.4%,91.5%,and 66.0%,respectively.When compared with endoscopic biopsy results,the sensitivity of 18F-FDG PET/CT for detecting gastric and intestinal involvement was 100.0%and 94.1%,respectively,with specificity of 75.0%and 100.0%,and accuracy of 92.9%and 94.7%,respectively.There were significant differences in the highest maximum standardized uptake value(SUVmax)and Ki-67 index between the classic and aggressive variants of MCL,with SUVmax positively correlated with Ki-67 index.By using SUVmax>10.4 as the diagnostic threshold,the sensitivity and specificity for differentiating between the classic and aggressive variants of MCL were 73.9%and 77.4%,respectively,with an AUC value of 0.797.Conclusion·18F-FDG PET/CT demonstrates a high detection rate for both intra-and extra-nodal lesions in MCL patients.It exhibits high specificity in diagnosing bone marrow involvement and high sensitivity and specificity in diagnosing gastrointestinal involvement,providing reliable non-invasive diagnostic information for MCL bone marrow and gastrointestinal involvement.However,it is not a substitute for pathological examination.Additionally,the positive correlation between SUVmax and Ki-67 index allows SUVmax to effectively differentiate between the classic and aggressive variants of MCL,with a higher SUVmax(>10.4)indicating a higher likelihood of the aggressive variant.These findings have clinical implications for treatment planning and prognosis assessment.

Objective:To explore the added value of T 1-weighted stack-of-stars volumetric interpolated body examination (StarVIBE) sequence on PET/MR image quality. Methods:A retrospective analysis was performed on 60 patients (42 males, 18 females; age 11-86 (58±12) years) who underwent 18F-FDG PET/MR examination and with positive PET results in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from April 2020 to April 2021. All patients completed StarVIBE sequence collection, and volumetric interpolated body examination (VIBE) sequence was used as control. StarVIBE and VIBE sequence images were evaluated independently using five-point method by two physicians. The evaluation was carried out from six aspects: lesion display, lesion boundary display, vascular around lesions display, fusion level with PET image, image artifact and overall image quality. Wilcoxon signed rank test was used to compare the image quality of the two sequences, and Kappa test was performed to assess the consistency of the image quality scores between the two physicians. Results:There were 26 cases with cervical lesions, 14 cases with chest lesions, 7 cases with abdomen lesions and 13 cases with pelvic lesions. The scores of lesion display (4.0(3.8, 4.5) vs 3.5(3.0, 4.0)), lesion boundary display (4.0(4.0, 4.0) vs 3.0(3.0, 3.5)), vascular around lesions display (5.0(4.0, 5.0) vs 4.0(3.5, 4.5)), fusion level with PET image (5.0(5.0, 5.0) vs 4.5(4.0, 5.0)), image artifact (4.5(4.0, 5.0) vs 4.5(4.0, 5.0)) and overall image quality (5.0(4.0, 5.0) vs 4.0(4.0, 4.0)) of StarVIBE sequences were better than those of VIBE sequences ( z values: 3.77-6.54, all P<0.001). On the vascular around the lesions display, the scores of StarVIBE were significantly better than those of VIBE sequence in the neck (5.0(4.5, 5.0) vs 3.0(2.7, 3.5); z=4.49, P<0.001) and chest (4.5(4.3, 4.7) vs 4.0(3.6, 4.3); z=3.10, P=0.002). As for image quality, the scores of StarVIBE were also significantly better than those of VIBE in neck (5.0(4.5, 5.0) vs 4.0(3.7, 4.5); z=4.36, P<0.001) and chest (5.0(5.0, 5.0) vs 4.0(4.0, 4.5); z=3.02, P=0.003). In abdominal lesions, the score of StarVIBE was higher than that of VIBE in blood vessels (4.5(3.5, 5.0) vs 4.0(3.5, 4.5); z=2.07, P=0.038), and there was no difference between score of overall image quality (4.0(3.7, 4.5) vs 4.0(3.5, 4.5); z=0.27, P=0.785). The score of overall image quality of pelvic StarVIBE sequence was better than that of VIBE sequence (5.0(4.5, 5.0) vs 4.0(4.0, 4.5); z=2.12, P=0.034). Kappa value of image quality score between two physicians was 0.554, indicating moderate consistency. Conclusion:In whole-body PET/MR imaging, StarVIBE sequence can significantly improve the image quality of cervical, thoracic and pelvic lesions when comparing with VIBE sequence.

Objective:To explore the diagnostic and grading value of combination of 68Ga -1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid- D-Phe1-Tyr3-Thr8-octreotide ( 68Ga-DOTA-TATE) and 18F-flurodeoxyglucose ( 18F-FDG) dual probes in multi-parameter positron emission tomography (PET)/magnetic resonance (MR) imaging in pancreatic neuroendocrine neoplasm (PNEN). Methods:From April 9th, 2020 to February 24th, 2022, in Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, the clinical data and the imaging of 68Ga-DOTA-TATE PET/MR and 18F-FDG PET/MR of 59 patients with pancreatic tumors (27 male, 32 female, aged 22 to 75 years old(51.8±13.3) years old), confirmed by surgical or biopsy pathology were retrospectively analyzed. All the cases were divided into PNEN group (42 cases) and non-PNEN group (17 cases) according to pathological results. Among which 39 patients with PNET were further divided into grade 1 group (G1 group, 27 cases) and grade 2 group (G2 group, 12 cases). Non-zero parameters were selected via the least absolute shrinkage and selection operator (LASSO) regression approach, and a logistic regression model was established by combination of the selected features and the corresponding non-zero coefficients. The measurement data with non-normal distribution were compared by Mann-Whitney U test. The receiver operating characteristic (ROC) curve were used to detemine the optimal cut off value to assess the dignostic efficiency. Results:Compared with those of non-PNEN group, the parameters of PNEN group increased, which included maximum standard uptake value of 68Ga-DOTA-TATE(SUV Gmax, 46.70 (22.37, 76.35) vs. 7.12 (4.75, 8.64)), mean standard uptake value of 68Ga-DOTA-TATE(SUV Gmean, 25.50 (13.18, 43.90) vs. 3.65 (2.89, 4.69)), peak standard uptake value of 68Ga-DOTA-TATE (SUV Gpeak, 27.17 (12.39, 46.97) vs. 5.46 (4.12, 6.56)), total lesion somatostatin receptor (SSR) expression (TLSRE, 68.21 (32.52, 440.96) vs. 26.02 (14.87, 69.57)), SUV Gmax/maximum standard uptake value of 18F-FDG (SUV Fmax, 12.71 (3.80, 21.70) vs. 1.10 (0.52, 2.35)), tumor to background ratio of 68Ga-DOTA-TATE (TBR G, 13.31 (5.54, 22.38) vs. 1.57 (1.31, 2.66)), tumor to liver ratio of 68Ga-DOTA-TATE(T/L G, 6.54 (2.90, 9.63) vs. 0.74 (0.65, 0.94)), tumor to spleen ratio of 68Ga-DOTA-TATE (T/S G, 2.36 (0.97, 3.70) vs. 0.25 (0.23, 0.38)), tumor to mediastinum ratio of 68Ga-DOTA-TATE (T/M G, 104.41 (34.03, 206.52) vs. 16.00 (12.87, 21.46)), SUV Gmax/minimum apparent diffusion coeffecient (ADC min, 55.14 (22.50, 96.37) vs. 6.76 (4.39, 12.76)) and SUV Gmean/ADC min (34.57 (13.47, 55.13) vs. 3.57 (2.46, 6.81)), and the differences were statistically significant ( U=28.00, 25.00, 32.00, 198.00, 54.00, 31.00, 28.00, 19.00, 10.00, 56.00 and 44.00, all P<0.01). The area under the curve (AUC) and diagnostic accuracy of dual-probe PET/MR imaging in the diagnosis of PNEN and non-PNEN were 0.941 and 96.6%, respectively. The AUC and diagnostic accuracy of model Y 1 in the diagnosis of PNEN and non-PNEN were 0.959 and 96.6%, respectively. There was no significant difference in AUC between model Y 1 and dual-probe PET/MR imaging in PNEN diagnosis ( P>0.05), however combining model Y 1 could improve the accuracy of PNEN diagnosis (100.0%). Compared with those of PNET G1 group, the parameters of G2 Group were higher, which included the maximum diameter of tumor (2.69 cm (2.08 cm, 5.00 cm) vs. 1.50 cm (1.20 cm, 2.50 cm)), metabolic tumor volume (MTV, 7.56 mL (4.45 mL, 53.57 mL) vs. 2.16 mL (1.22 mL, 5.48 mL)), total lesion glycolysis (TLG, 22.24 (11.95, 189.85) vs. 3.81 (2.11, 18.67)), tumor to background ratio of 18F-FDG (TBR F, 2.94 (2.00, 3.96) vs. 1.48 (1.29, 3.72)), tumor to liver ratio of 18F-FDG (T/L F, 2.32 (1.35, 2.98) vs. 1.08 (0.90, 2.17)) and SSR-expressing tumor volume (SRETV, 8.00 (3.06, 40.00) vs. 1.91 (0.95, 4.88)), and the differences were statistically significant ( U=66.00、66.00、77.00、93.00、90.00、65.50, all P<0.05). The maximum diameter of tumor was the best single parameter for the differential diagnosis of PNET G2 and G1, AUC was 0.796 and the cutoff value was 1.90 cm. The model Y 2, which combined the maximum diameter of tumor and TBR G had an AUC of 0.835 for the differential diagnosis of PNET G2 and G1. There was no significant difference in AUC between the maximum diameter of tumor and model Y 2 ( P>0.05). However the combination of the maximum diameter of tumor and model Y 2 could improve the accuracy of differential diagnosis of PNET G2 and G1 (94.87%). Conclusion:The combination of multi-parameter of 68Ga-DOTA-TATE and dual-probe 18F-FDG PET/MR imaging can improve the diagnostic and grading accuracy of PNEN, which may be helpful in the selection of clinical treatment for patients.

Objective:To explore the diagnostic value of 18F-fluorodeoxyglucose (FDG) PET/MR imaging for liver metastasis. Methods:A retrospective analysis of 75 cases (46 males, 29 females; age (58.9±14.3) years) with suspected liver metastases from January 2020 to October 2020 in Ruijin Hospital were performed. All patients underwent PET/MR and enhanced upper abdominal CT scans. Diagnostic efficacies of enhanced CT, PET, MR and PET/MR for liver metastases (based on lesions and patients respectively) were calculated and compared (McNemar test).Results:A total of 306 liver lesions were detected in 75 patients, of which 179 lesions in 45 patients were confirmed as liver metastases through follow-up or pathology. In lesion-based analysis, the sensitivities of enhanced CT, PET, MR and PET/MR were 74.9%(134/179), 60.3%(108/179), 98.9%(177/179) and 100%(179/179), with specificities of 96.9%(123/127), 100%(127/127), 92.9%(118/127) and 92.1%(117/127), respectively. The diagnostic efficacy of PET/MR was significantly higher than that of enhanced CT and PET ( χ2 values: 51.000 and 81.000, both P<0.001), but there was no statistical difference between PET/MR and MR ( χ2=2.000, P=0.368). In patient-based analysis, the sensitivities of enhanced CT, PET, MR and PET/MR were 82.2%(37/45), 84.4%(38/45), 95.6%(43/45) and 100%(45/45), with specificities of 86.7%(26/30), 100%(30/30), 70.0%(21/30) and 70.0%(21/30), respectively. The diagnostic efficacies of enhanced CT and PET were statistically different from PET/MR ( χ2 values: 13.000 and 16.000, both P<0.05), but there was no statistical difference between MR and PET/MR ( χ2=2.000, P=0.368). Conclusions:Compared with enhanced CT, PET and MR, 18F-FDG PET/MR has a higher detective rate for liver metastases. The overall diagnostic efficacy of 18F-FDG PET/MR is better than enhanced CT and PET alone, but similar to MR.

INTRODUCTIONPneumonia is associated with considerable mortality. However, there is limited information on age-specific prognostic factors for death from pneumonia.

METHODSPatients hospitalised with a diagnosis of pneumonia through the emergency department were stratified into three age groups: 18-64 years, 65-84 years and ≥ 85 years. Multivariate logistic regression and receiver operating characteristic curve analyses were conducted to evaluate prognostic factors for mortality and the performance of pneumonia severity scoring tools for mortality prediction.

RESULTSA total of 1,902 patients were enrolled (18-64 years: 614 [32.3%]; 65-84 years: 944 [49.6%]; ≥ 85 years: 344 [18.1%]). Mortality rates increased with age (18-64 years: 7.3%; 65-84 years: 16.1%; ≥ 85 years: 29.7%; p < 0.001). Malignancy and tachycardia were prognostic of mortality among patients aged 18-64 years. Male gender, malignancy, congestive heart failure and eight other parameters reflecting acute disease severity were associated with mortality among patients aged 65-84 years. For patients aged ≥ 85 years, altered mental status, tachycardia, blood urea nitrogen, hypoxaemia, arterial pH and pleural effusion were significantly predictive of mortality. The Pneumonia Severity Index (PSI) was more sensitive than CURB-65 (confusion, uraemia, respiratory rate ≥ 30 per minute, low blood pressure, age ≥ 65 years) for mortality prediction across all age groups.

CONCLUSIONThe predictive effect of prognostic factors for mortality varied among patients with pneumonia from the different age groups. PSI performed significantly better than CURB-65 for mortality prediction, but its discriminative power decreased with advancing age.

Adolescent ; Adult ; Age Factors ; Aged ; Aged, 80 and over ; Algorithms ; Community-Acquired Infections ; diagnosis ; mortality ; Female ; Hospitalization ; Humans ; Male ; Middle Aged ; Multivariate Analysis ; Patient Admission ; Pneumonia ; diagnosis ; mortality ; Predictive Value of Tests ; Prognosis ; ROC Curve ; Risk Factors ; Sensitivity and Specificity ; Severity of Illness Index ; Singapore ; epidemiology ; Young Adult

Objective To explore the value of CT spectral imaging in the demonstration of pancreatic ductal adenocarcinoma (PDAC).Methods 113 patients were scanned by CT spectral,and gemstone spectral imaging (GSI) was performed in late arterial phase (AP) and portal venous phase (PP).All diagnosis were pathologically confirmed.The ROIs were placed on the lesion and on the pancreatic parenchyma.The ROI files including the CTmono values and the normalized CTmono values (normalized to pancreatic parenchyma) were saved.The works were performed three times repeatedly.CNR values ranged from 40 keV to 140 keV and the optimal keV in AP and PP were calculated.The differences of CTmono values, normalized CTmono values,and CNR were compared between the optimal keV and 70 keV(equivalent to conventional 120 kVp energy level).Paired t-test and Wilcoxon signed rank test were performed.P<0.05 was considered statistically significant.Results The optimal monochromatic energy of PDAC were 40 keV in both AP and PP.The optimal CNR values(mean±standard) were 2.31±1.02 and 2.38±1.02 in AP and PP,while the corresponding values of 70 keV were 2.08±0.98 and 2.12±0.96.The CNR of 40 keV was higher than that of 70 keV in both AP and PP.The CTmono values of PDAC were (58±13) HU and (71±19) HU at 70 keV and were (111±44) HU and (155±57) HU at 40 keV in AP and PP.The CTmono value in PP was higher than in AP.The median of normalized CTmono values of PDAC at 40 keV were 47.0% and 53.9% in AP and PP, and were lower than those of 70 keV,which were 57.7% and 61.8%.The differences of normalized CTmono values between 40 keV and 70 keV were significant.Conclusion CT spectral imaging manifests that PDAC is hypovascular both in AP and PP and is progressively enhanced form AP to PP.There is maximal conspicuity of tumor in AP, and the optimal monochromatic imaging can improve the conspicuity of PDAC lesion.