Objective To explore the quantitative characteristics of pancreatic ductal adenocarcinoma(PDAC) in single-source dual energy spectral CT imaging. Methods From January 2013 to December 2014, 113 patients underwent dual phase contrast-enhanced gemstone spectral imaging(GSI) on Discovery CT 750 HD. All diagnoses were pathologically confirmed by surgery or biopsy. The spectral HU curves of PDAC were observed, the monochromatic CT values, the effective atomic number(Zef ), the iodine concentration(IC), water concentration(WC), and the corresponding normalized values(normalized monochromatic CT values, normalized Zef , normalized IC, normalized WC)of the lesion and the pancreatic parenchyma in late arterial phase(AP) and portal venous phase(PP) were recorded . The measurements were performed three times repeatedly. Paired t test (normal distribution) or Wilcoxon test (non-normal distribution) were used for analyzing the differences between the two phases and between PDAC and pancreatic parenchyma. Results The monochromatic CT values of PDAC in AP were lower than in PP at each energy level and the difference was more marked at lower energy. The normalized monochromatic CT values increased with the increase of energy level in both AP and PP and the difference was more distinct at lower energy. The Zef , IC and normalized IC of PDAC all had significant differences(P<0.05), while the WC, normalized Zef , and normalized WC had no difference between AP and PP. The Zef and IC of pancreatic parenchyma had significant differences(P<0.05), while the WC had no difference between AP and PP. The differences of Zef , IC, and WC between PDAC and pancreatic parenchyma were significant in both two phases (P<0.05). Conclusions Dual phase CT spectral imaging showed characteristic quantitative parameters of pancreatic ductal adenocarcinoma. The monochromatic CT values, Zef , and iodine concentration of PDAC were lower than those of pancreatic parenchyma in both AP and PP. The monochromatic CT values, Zef , and iodine concentration of PDAC in late arterial phase were lower than those in portal venous phase. The differences were all more distinct at lower energy.

Objective To assess the value of computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of pancreatic neuroendocrine neoplasms (PNEN) and to analyze the factors influencing thepreoperative imaging diagnosis of PNEN.Methods From January 2016 to November 2016, patients with PNEN diagnosed by surgery and biopsy were collected. CT and MRI data of them were analyzed. The CT values or signal intensity of the lesions and the pancreatic parenchyma were measured and the contrast-to-noise ratio (CNR) of the lesion was calculated. Detecting sensitivity and diagnosis accuracy of CT and MRI were compared. Detecting sensitivity of different MRI sequences was also analyzed. Diagnosis accuracy of non-functional PNEN and functional PNEN was compared and analyzed. Lesion CNR was compared between arterial phase and portal venous phase of the contrast enhanced CT. The sensitivity, accuracy and constituent ratio were compared by nonparametric analysis. Independent sample t test and one-way analysis of variancewere performed for the quantitative parameters comparison. Results A total of 54 patients with 56 lesions of PNEN were included for two of whom had two lesions each. CT and MRI were both performed in 44 patients (46 lesions).Detecting sensitivity and diagnosis accuracy of CT were 97.8% (45/46) and87.0% (40/46), respectively. Detecting sensitivity of MRI were 97.8% (45/46) and89.1% (41/46), respectively. There was no significant difference in detecting sensitivity and diagnosis accuracy between CT and MRI (both P>0.05). The CNR of lesion in arterial phase was higher than that of portal venous phase(4.7±3.8 vs 3.4±2.5), and the difference was statistically significant (t=2.949, P<0.05). Detecting rates of T1 weighted imaging with fat suppression (T1WI-FS) image, T2 weighted imaging with fat suppression (T2WI-FS) image, diffusion weighted imagingand dynamic contrast enhanced T1WI-FS image were 90.0% (45/50), 88.0%(44/50), 86.0%(43/50), and 91.7% (44/48), respectively. There was no significant difference in detecting rate among these images sequences (Q=2.526, P=0.510). Tumor diameter in non-functional PNEN was significantly larger than that in functional PNEN ((2.9±1.6) cm vs (1.7±0.7) cm)(t=3.479,P<0.05). The overall diagnosis rate of non-functional PNEN with CT and MRI before operation was 70.8% (17/24), which was significantly lower than that of functional PNEN (100.0%, 31/31) (χ2=10.360，P=0.002).Conclusions CT and MRI are both sensitive in detectingPNEN, and they were two complementary modalities. CT image in arterial phase delineated the lesion better than that in portal venous phase. MRI images with different sequences can becomplementary and there is no significant difference in detecting sensitivity for PNEN among different sequences. CT and MRI play an equal rolein the diagnosis of PNEN before operation. Because of atypical CT and MRI findings, the diagnosis of non-functional PNEN is more difficult thanfunctional PNEN.

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.

Objective:To investigate the features of median arcuate ligament syndrome (MALS) in computed tomography angiography (CTA).Methods:The retrospective and descriptive study was conducted. The clinical and imaging data of 56 patients with MALS who were admitted to Ruijin Hospital, Shanghai JiaoTong University School of Medicine from November 2019 to October 2020 were collected. There were 30 males and 26 females, aged from 19 to 78 years, with a median age of 54 years. All 56 patients underwent CTA. Observation indicators: (1) CTA examination; (2) correlation analysis; (3) surgical situations. Measurement data with normal distribution were represented as Mean± SD. Count data were described as absolute numbers or percentages. Spearman correlation analysis with test level of 0.05 was used to analyze the correlation between celiac trunk stenosis and the distance between the original location of celiac trunk and original location of superior mesenteric artery and the minimum distance of celiac trunk and superior mesenteric artery. Results:(1) CTA examination. ① Celiac trunk stenosis: results of cross sectional examina-tion of CTA showed that of 56 patients, there were 2 cases of celiac trunk occlusion, 10 cases of severe stenosis, 9 cases of moderate stenosis and 35 cases of mild stenosis. Results of sagittal examination of CTA showed that of 56 patients, there were 2 cases of celiac trunk occlusion, 21 cases of severe stenosis, 15 cases of moderate stenosis and 18 cases of mild stenosis. ② Examination of patients with different degree of vascular stenosis: according to the results of sagittal examination of CTA, the 2 cases with celiac trunk occlusion were negative for aneurysms, aortic dissection or vascular variations but positive for compensated varix of the anterior and posterior pancreatico-duodenal arches. Of the 21 cases with celiac trunk severe stenosis, 2 cases were positive for aneurysms, 1 case was positive for aortic dissection, 7 cases were positive for compensated varix of the anterior and posterior pancreaticoduodenal arches, 8 cases were positive for collateral circula-tions of anterior and posterior pancreaticoduodenal archs and 8 cases were positive for vascular variation. Of the 15 cases with celiac trunk moderate stenosis, 2 cases were positive for aneurysms, 3 cases were positive for aortic dissection, 2 cases were positive for compensated varix of the anterior and posterior pancreaticoduodenal arches, 4 cases were positive for collateral circulations of anterior and posterior pancreaticoduodenal archs and 7 cases were positive for vascular variation. Of the 18 cases with celiac trunk mild stenosis, 1 case was positive for aneurysms, 2 cases were positive for aortic dissection, 7 cases were positive for collateral circulations of the anterior and posterior pancreaticoduodenal arches, 6 cases were positive for vascular variation. All 56 patients were negative for ischemia of liver, spleen and stomach. ③ Original location of celiac trunk: of 56 patients, there were 43 cases had celiac trunk originated horizontally from the lower edge of T12 vertebral body, 2 cases had celiac trunk originated from the middle of T12 vertebral body, 1 case had celiac trunk originated from the upper part of T12 vertebral body, 7 cases had celiac trunk originated from the upper part of L1 vertebral body, 1 case had celiac trunk originated from the middle of L1 vertebral body and 2 cases had occluding celiac trunk. (2) Correlation analysis: results of sagittal observation on CTA examination showed the distance between the original location of celiac trunk and original location of superior mesenteric artery of the 56 patients was (6.0±4.0) mm. The distance between the original location of celiac trunk and original location of superior mesenteric artery of patients with celiac trunk mild, moderate or severe stenosis were (6.2±2.8)mm, (8.1±4.4)mm and (5.3±3.2)mm respectively. There were 23 cases of the 56 patients had the distance between the original location of celiac trunk and original location of superior mesenteric artery <5 mm. Results of correlation analysis showed that the degree of celiac trunk stenosis was not related to the distance between the original location of celiac trunk and original location of superior mesenteric artery ( r=?0.205, P>0.05). Results of sagittal observation on CTA examination showed the shortest distance between celiac trunk and superior mesenteric artery of the 56 patients was (3.8±2.4)mm. The shortest distance between celiac trunk and superior mesenteric artery of patients with celiac trunk mild, moderate or severe stenosis were (4.2±2.0)mm, (4.4±3.3)mm and (3.0±1.9)mm, respectively. There were 45 cases of the 56 patients had the shortest distance between celiac trunk and superior mesenteric artery <5 mm. Results of correlation analysis showed that the degree of celiac trunk stenosis was not related to the shortest distance between celiac trunk and superior mesenteric artery ( r=?0.249, P>0.05). (3) Surgical situations: of 56 patients, 2 cases were positive for clinical symptoms of abdominal pain, 54 cases were negative for clinical symptoms, 4 cases under-went surgical treatment and 52 cases not underwent surgical treatment. Of the 4 cases undergoing surgical treatment, 2 cases with abdominal pain were diagnosed as MALS by upper abdominal CTA. Celiac trunk of the 2 cases were severe stenosis and stents implantation under celiac arteriography were performed. Results of postoperative CTA showed celiac trunk was negative for obvious stenosis. The other 2 cases who were negative for clinical symptoms of MALS were planed to pancreaticoduo-denectomy for pancreatic head tumor. Results of preoperative CTA showed severe stenosis of celiac trunk and arterial bypass grafting was performed for the 2 cases during pancreaticoduodenectomy to alleviate liver ischemia caused by gastroduodenal artery ligation which would avoid the incidence of postoperative MALS associated complications. Result of postoperative CTA three-dimensional reconstruction showed the bypass vessel was unobstructed. Conclusion:Based on sagittal result of CTA examination, the stenosis of celiac trunk, the anatomical relationship between celiac trunk and arcuate ligament and the original location of celiac trunk of MALS patients can be evaluated.