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Objective@#To investigate the value of combined chemical exchange saturation transfer (CEST) and conventional magnetizationtransfer imaging (MT) in detecting metabolic and structural changes of renal fibrosis in rats with unilateral ureteral obstruction(UUO) at 3T MRI. @*Materials and Methods@#Thirty-five Sprague-Dawley rats underwent UUO surgery (n = 25) or sham surgery (n = 10). Theobstructed and contralateral kidneys were evaluated on days 1, 3, 5, and 7 after surgery. After CEST and MT examinations,18F-labeled fluoro-2-deoxyglucose positron emission tomography was performed to quantify glucose metabolism. Fibrosis wasmeasured by histology and western blots. Correlations were compared between asymmetrical magnetization transfer ratio at1.2 ppm (MTRasym(1.2ppm)) derived from CEST and maximum standard uptake value (SUVmax) and between magnetization transferratio (MTR) derived from MT and alpha-smooth muscle actin (α-SMA). @*Results@#On days 3 and 7, MTRasym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly different from those ofcontralateral kidneys (p < 0.05). On day 7, MTRasym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly differentfrom those of sham-operated kidneys (p < 0.05). The MTRasym(1.2ppm) of UUO renal medulla was fairly negatively correlated withSUVmax (r = -0.350, p = 0.021), whereas MTR of UUO renal medulla was strongly negatively correlated with α-SMA (r = -0.744, p <0.001). @*Conclusion@#CEST and MT could provide metabolic and structural information for comprehensive assessment of renal fibrosisin UUO rats in 3T MRI and may aid in clinical monitoring of renal fibrosis in patients with chronic kidney disease.
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Objective To investigate the feasibility of the CT texture analysis (CTTA)in differentiating autoimmune pancreatitis (AIP)from pancreatic ductal adenocarcinoma (PDAC).Methods 25 patients with AIP and 31 patients with PDAC who confirmed by pathological or clinical underwent pretreatment three-phase contrast-enhanced CT were enrolled.Histogram parameters (mean CT values,median CT values,25 th,75 th percentile CT values,skewness,kurtosis,entropy and uniformity)were derived from CT images through texture analysis.The differences of histogram parameters between AIP and PDAC groups were compared.ROC and AUC were used to evaluate the diagnostic efficacy of histogram parameters in differentiating AIP from PDAC.Results The values for mean CT values,median CT values,25 th,75 th percentile CT values and uniformity of AIP were significantly higher than those of PDAC group,while the values for entropy of AIP were significantly lower than those of PDAC group in arterial phase,portal phase,and delay phases (all P＜0.05). There were no significant differences in kurtosis and skewness between AIP and PDAC groups (all P＞0.05).The uniformity in portal phase achieved the optimal diagnostic accuracy in differentiating AIP from PDAC (AUC＝0.973 ),the cutoff value was 0.797,the corresponding sensitivity and specificity were 92% and 9 6.8%,respectively.Conclusion CTTA can be used as a quantitative analysis method for differential diagnosis between AIP and PDAC,providing a reference for clinicians to select therapeutic schedules.
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Objective To investigate the features of computed tomography (CT) and magnetic resonance imaging (MRI) on pancreatic neuroendocrine tumors (pNENs).Methods The retrospective and descriptive study was adopted.The clinicopathological data of 33 patients with pNENs who were admitted to the Tongji Hospital of Tongji Medical School of Huazhong University of Science and Technology between May 2012 and February 2016 were collected.All the patients underwent plain and enhanced scans of CT and MRI.Observation indicators:(1) overall imaging findings and pathological results of pNENs,(2) imaging findings of functional pNENs,(3) imaging findings of non-functional pNENs.Main analysis indicators included tumor diameter,location,boundary,density,cystic degeneration,enhancement,signal,calcification,with or without pancreaticobiliary duct dilation,with or without surrounding tissues invasion,lymph node and distant organ metastases.Results (1) Overall imaging findings and pathological results of pNENs:of 33 patinets with pNENs,24 underwent CT examination,3 underwent MRI examination and 6 underwent CT and MRI examinations.Tumors of 33 patients were solitary with a diameter of 0.6-16.0 cm.Ten,1,13 and 9 tumors were respectively located at the head of pancreas,uncinate process of pancreas,body of pancreas and tail of pancreas.Thirty-three patients were diagnosed as pNENs by pathological examination,including 20 with functional pNENs (insulinoma) and 13 with non-functional pNENs,and G1,G2 and G3 were respectively detected in 24,7 and 2 patients.The coincidence rate between preoperative CT or MRI examination and pathological examination was 90.9％ (30/33).One,1 and 1 patients were misdiagnosed as pancreatic cancer,enlargement of peripancreatic lymph nodes and duodenal gastrointestinal stromal tumor,respectively.(2) Imaging findings of functional pNENs:tumor diameter of 20 patients with functional pNENs was 0.6-3.0 cm with an average diameter of 1.5 cm.Fòur,10 and 6 tumors were respectively located at the head of pancreas,body of pancreas and tail of pancreas.Of 20 patients with functional pNENs,tumors of 19 patients showed clear boundary and 1 showed unclear boundary,and tumors of 18 patients had uniform density and 2 had uneven density with cystic degeneration,without the occurrence of calcification.Of 20 patients undergoing dynamic enhanced scans,tumors of 19 patients demonstrated obvious enhancement in arterial phase and slightly obvious enhancement or were equal to normal pancreatic tissues in portal vein phase and lag phase,and tumor of 1 patient demonstrated slight enhancement in arterial phase and was equal to or less than normal pancreatic tissues in portal vein phase and lag phase.Tumors in 3 patients undergoing MRI scans were manifested as hypointensity on T1-weighted imaging (T1WI),hyperintensity on T2WI and hyperintensity on DWI (b =1 000 s/m2),with clear imaging.Of 20 patients,1 was accompanied with atrophy of pancreatic tissues at distal tumor,pancreatic duct dilatation,multiple retention cyst and enlargement of lymph nodes around the hepatic artery.(3) Imaging findings of non-functional pNENs:tumor diameter of 13 patients with non-functional pNENs was 1.5-16.0 cm with an average diameter of 5.0 cm.Six,1,3 and 3 tumors were respectively located at the head of pancreas,uncinate process of pancreas,body of pancreas and tail of pancreas.Of 13 patients with non-functional pNENs,tumors of 11 patients showed clear boundary and 2 showed unclear boundary,tumors of 3 patients had uniform density and 10 had uneven density with cystic degeneration,and tumors of 2 patients had calcification.Of 13 patients undergoing dynamic enhanced scans,tumors of 12 patients demonstrated obvious enhancement in arterial phase,continuous enhancement in portal vein phase and lag phase and less obvious enhancement at cystic degeneration area,with marked enlargement of supplying arteries and draining veins in partial tumors.Tumor of 1 patient demonstrated slight enhancement,and its enhancement was slightly less than normal pancreatic tissues in arterial phase,portal vein phase and lag phase,with unclear boundary.Results of MRI scans in 6 patients showed that tumors of 4 patients were manifested as hypointensity on T1WI,slight hyperintensity or mixed signal on T2WI and hyperintensity on DWI (b =1 000 s/m2),and tumors of 2 patients were manifested as hypointensity on T1WI,hypointensity on T2WI and hyperintensity on DWI (b =800 s/m2).Of 13 patients with non-functional pNENs,4 had pancreaticobiliary duct dilation and 7 had local tissues invasion or distant organ metastasis (4 with liver metastasis,1 with peripanereatic lymph node metastasis,1 with liver and peripancreatic lymph node metastases and 1 with liver metastasis combined with splenic venous and arterial invasion),including 1 in G1,4 in G2 and 2 in G3.Of 5 patients with tumor diameter ＞ 5.0 cm,4 were complicated with liver or lymph node metastases.Conclusions CT and MRI features of pNENs have a certain characteristics.For functional pNENs,benign and solid tumor is common,with clear boundary and smaller diameter.For non-functional pNENs,tumor size is bigger and cystic necrosis occurs within the tumor,with various enhancements.
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Objective To validate the feasibility and accuracy of iterative decomposition of water and fat with asymmetry and least squares estimation-quantitative fat imaging (IDEAL-IQ) in fat quantification using fat-water model. Methods A homogeneous fat-water mixture model consisting of various known fat-fractions were described, and the fat fraction was 0.00, 0.01, 0.02, 0.04, 0.06, 0.08, 0.10, 0.14, 0.18, 0.22, 0.26, 0.30 g/ml respectively. A water-vaseline separated model was also described. IDEAL-IQ was performed. Thin slices were acquired for fat-water mixture model and repeated 3 days later. Nineteen slices of 14 mm-thick parallel to the water-vaseline boundary in 1 mm steps from vaseline to water were acquired. The fat-fractions in 11 slices of fat-water mixture model were measured on FatFrac images. Accuracy was assessed through single sample t test or Kolmogorov-Sirmov test. Measured fat-fractions of the same known fat-fraction were assessed through independent samples t test between two scan times. Linear regression was used to assess the relationship between known fat-fractions and measured fat-fractions. Slices containing the water-vaseline boundary were measured with ROI in the middle of the FatFrac images. The relationship between measured fat-fractions and locations of scanning was exploded using curve fitting. Results (1) Fat-water mixture model: no significant difference(P>0.05) was found between measured fat-fractions and known fat-fractions when it was 0.00, 0.02, 0.06 and 0.08 g/ml with the measured fat-fractions 0.60%, (2.30 ± 0.60)%, (5.76 ± 1.40)%, (7.62 ± 1.40)% respectively for the first time. No significant difference(P>0.05) was found between measured fat-fractions and known fat-fractions when it was 0.00, 0.02, 0.10 g/ml with the measured fat-fractions 0.04%, (2.32 ± 0.60)%, (9.41 ± 1.00)%respectively for the second time. Measured fat-fraction was inlinear relation with known fat-fraction:Y=0.898X+0.224, r2=0.993, P<0.01, F=36 129.548.(2) Water-vaseline separated model: measured fat-fraction increased as scanning location changed, Y=0.045X2-0.499X-4.474, r2=0.978, P<0.05, F=350.623.Conclusions IDEAL-IQ can be used to quantify fat content with good repeatability and can accurately assess the actual fat content from the linearrelationship.