| Part One:Comparison of spectral CT and conventional CT in preoperative diagnosis of insulinomaObjective To investigate the value of spectral CT in preoperative diagnosis of insulinomas in comparison with conventional multi-detector CT(MDCT).Materials and methods The clinical and imaging data of 14 cases of insulinoma with spectral CT examination and 11 cases of insulinoma with conventional MDCT examination were comparatively analyzed. Student T test was performed to compare the age,time between CT scan and operation,duration of symptoms,tumor size and contrast-to-noise ratio(CNR) in the two groups.Fisher’s exact test was performed to compare the gender and location of tumor in the two groups.The preoperative detection rate for insulinoma of conventional MDCT,spectral CT and different kinds of images of spectral CT(Mono,Iodine) were also compared with Fisher’s exact test.Results There were 16tumors(14 patients, 2 patients with 2 tumors) in spectral CT group diagnosed by histopathology.There were 14 tumors(11 patients, 1 patient with 2 tumors and 1 patient with 3tumors) in conventional MDCT group diagnosed by histopathology.The age[(50.31±0.47)year,(44.93±0.69)year)],gender[(male:female=8:6),(male:female=7:4)],time between CT scan and operation[(8.38±0.33)day,(7.01±0.30)day],duration of symptoms[(32.89±5.12)month,(28.36±6.87)month],tumor size[(25.8±0.34)mm,(24.1±0.47)mm]and location[(h-n:b-t=10:6),(h-n:b-t=11:3)] between spectral CT group and conventional MDCT group had no differences(P values were greater than 0.05).The detection rate of optimal single energy images(81.2%), iodine-based material decomposition images(87.5%) and the combination of them(93.8%) were all higher than that of conventional MDCT(71.4%), but the differences had no statistical significance(P values were greater than 0.05).The CNR of iodine-based material decomposition images(3.86±2.43) and optimal single energy images(3.74±2.18) were higher than that of conventional MDCT(3.13±2.52), the differences were statistically significant(P = 0.025,P=0.031).Conclusion With the combination of the different images spectral CT improved theperformance of preoperative diagnosis for insulinomas compared with conventional MDCT.Part Two:The value of CT spectral imaging in the differential diagnosis of chronic mass-forming pancreatitis and pancreatic ductal adenocarcinomaObjective To investigate the value of CT spectral imaging in the differential diagnosis of chronic mass-forming pancreatitis and pancreatic ductal adenocarcinoma.Materials and methods The clinical and imaging data of 14 cases with chronic mass-forming pancreatitis and 26 cases with pancreatic ductal adenocarcinoma were retrospectively analyzed. All patients underwent dual-phase(arterial phase, AP; pancreatic parenchymal phase, PP) enhanced CT with dual-energy spectral imaging mode. Quantitative parameters including normalized iodine concentration(NIC),water concentration and the slope of spectral curve(slope) were measured and calculated. Student T test was performed to compare the quantitative parameters between chronic mass-forming pancreatitis and pancreatic ductal adenocarcinoma. The receiver operating curves(ROC curves)were performed to evaluate the diagnostic performance in differentiating chronic mass-forming pancreatitis from pancreatic ductal adenocarcinoma.Results In both AP and PP, the NIC(0.25±0.17,0.46±0.22) and slope(1.42±0.76,2.74±1.53) of chronic mass-forming pancreatitis group were higher than the NIC(0.06±0.03,0.22±0.07) and slope(0.92±0.46,1.27±0.50) of pancreatic ductal adenocarcinoma group respectively, and the differences were statistically significant(P<0.05).The water concentration in both AP and PP had no differences(P=0.603,P=0.700).The ROC curves showed that NIC in AP(0.864)had the highest the area under the curve(AUC), its threshold was 0.100, and the corresponding sensitivity and specificity were71.4%, 88.5%.Conclusion CT spectral imaging with the quantitative analysis of iodine concentration may help to increase accuracy of differentiating chronic mass-forming pancreatitis from pancreatic ductal adenocarcinoma.Part Three:Differential diagnosis of pancreatic cystic lesions with the quantitative analysis of spectral CTObjective To investigate the imaging characteristics of solid pseudopapillary epithelial neoplasm(SPEN),mucinous cystic neoplasms(MCNs) and pancreatic pseudocyst using spectral CT,and to evaluate whether quantitative information derived from CT spectral imaging can improve the differential diagnosis of these lesions.Materials and methods The clinical and imaging data of 51 cases of pancreatic cystic lesions were retrospectively analyzed, including 22 cases of pancreatic pseudocyst, 18 cases of MCNs and 11 cases of SPEN. All patients underwent dual-phase(arterial phase, AP; pancreatic parenchymal phase, PP) enhanced CT with dual-energy spectral imaging mode.The differences between qualitative parameters were compared with Fisher’s exact test.The differences between quantitative parameters were compared with variance analysis.The receiver operating characteristic curves(ROC curves) were performed to evaluate the diagnostic performance of quantitative parameters which had statistical significance between the three groups.Logistic regression was performed for multiparametric analysis. Results The average age of the three groups were from large to small MCNs(58.56±10.48), pseudocyst(45.23 + 12.52)and SPEN(36.09 + 18.27)(P=0.000).Patients with pseudocyst were all symptomatic, the majority of patients with MCNs had symptoms, while patients with SPEN were less symptomatic(P=0.013).The majority of SPEN contained solid component( 72.7%),while a minority of pseudocyst contained solid component(0.09%)(P=0.001).The slope of spectral curve of pancreatic pseudocyst(0.27 + 0.14,0.26 + 0.17), MCNs(0.58±0.22,0.58±0.20) and SPEN(1.17+ 0.31,1.25 + 0.37) in both AP and PP had significant difference(P=0.000).The iodine(water)concentration of pancreatic pseudocyst(1.53±1.01,1.45±1.01), MCNs(3.28±1.36,3.31±1.39)and SPEN(7.96±1.93,8.41±3.04)in both AP and PP had significant difference(P=0.000).The calcium(water) concentration of pancreatic pseudocyst( 2.03±1.18, 2.11±1.21), MCNs(4.82±1.87,4.08±1.83) and SPEN(10.23±2.43,10.69±4.05)in both AP and PP had significant difference(P=0.000, P=0.000).The Effective-Z of pancreatic pseudocyst(7.57±0.10,7.57±0.11),MCNs(7.80±0.12,7.80±0.12) and SPEN(8.11±0.16,8.13±0.15)in both AP and PP had significant difference(P=0.000, P=0.000). The multiparametric analysis showed that the canonical discriminant function coefficient of slope of spectral curve, Effective-Z, iodine(water)concentration, calcium(water) concentration were-868.13,2742.64,-162.67,66.499 in AP and-190.99,206.55,63.20,-34.09 in PP,and the constant was-11133.07.Conclusion The cystic component of the pancreatic cystic lesions had different quantitative characteristics in CT spectralimaging, which could provided additional information and improved the diagnostic performance.Part Four:The study of spectral CT in preoperative staging of pancreatic ductal adenocarcinomaObjective To investigate the value of spectral CT in preoperative assessment of the TNM staging of pancreatic ductal adenocarcinoma.Materials and methods The clinical and imaging data of 34 cases of pancreatic ductal adenocarcinoma were retrospectively analyzed. All patients underwent dual-phase(arterial phase, AP; pancreatic parenchymal phase, PP) enhanced CT with dual-energy spectral imaging mode.Quantitative parameters including iodine concentration, water concentration and the monochromatic CT values at 40 to 140 ke V(with 10 ke V increment) in AP were measured and recorded. Student T test was performed to compare the quantitative parameters.Results The monochromatic CT values at 40 to 140 ke V and iodine concentration of the affected fat were higher than those of the normal fat, and the differences were statistically significant(P <0.05).There was no significant difference in the water concentration between the affected fat and the normal fat(P > 0.05).There were no significant differences in the monochromatic CT values at40 to 140 ke V, iodine concentration and water concentration between the metastatic lymph node and pancreatic ductal adenocarcinoma(P>0.05).There waere no significant differences in the monochromatic CT values at 40 to 140 ke V, iodine concentration and water concentration between the hepatic metastasis and pancreatic ductal adenocarcinoma(P>0.05).Conclusion The quantitative analysis of spectral CT can distinguish the normal fat and the affected fat, and determine the homology of lymph nodes, liver lesions and pancreatic ductal adenocarcinoma,which is helpful to the preoperative evaluation of the TNM staging of pancreatic ductal adenocarcinoma. |
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