[Effect of Deep Learning-based Contrast-enhanced CT Image Reconstruction on the Image Quality of the Biliary System].

Objective To evaluate the effect of a deep learning reconstruction (DLR) method on the visibility of contrast-enhanced CT images of the biliary system by comparing it with different iterative reconstruction algorithms including the adaptive iterative dose reduction 3D (AIDR 3D) algorithm,forward projected model based iterative reconstruction solution (FIRST),and filtered back projection (FBP) algorithm. Methods A total of 30 patients subjected to abdominal contrast-enhanced CT and diagnosed with dilatation of common bile duct or extrahepatic bile duct were retrospectively included in this study.The images of the portal phase were reconstructed via four different algorithms (FBP,AIDR 3D,FIRST,and DLR).Signal to noise ratio (SNR) and contrast to noise ratio (CNR) of the dilated bile duct,liver parenchyma,measurable bile duct lesions,and image noise were compared between the four datasets.In subjective analyses,two radiologists independently scored the image quality (best:4 points,second:3 points;third:2 points;fourth:1 point) of the four datasets based on the noise and image visual quality of the biliary system.The Friedman and the Bonferroni-Dunn post-hoc tests were performed for comparison. Results The DLR images (bile duct:4.42±0.87;liver parenchyma:3.78±1.47) yielded higher CNR than the FBP (bile duct:2.21±1.02,P<0.001;liver parenchyma:1.43±1.29,P<0.001),AIDR 3D (bile duct:2.81±0.91,P=0.024;liver parenchyma:2.39±1.94,P=0.278),and FIRST (bile duct:2.51±1.24,P<0.001;liver parenchyma:2.45±1.81,P=0.003) images.Furthermore,the DLR images had higher SNR (bile duct:1.39±0.85,liver parenchyma:9.75±1.90) than the FBP (bile duct:0.86±0.63,P<0.001;liver parenchyma:3.31±1.12,P<0.001) and FIRST (bile duct:1.01±0.61,P=0.013;liver parenchyma:5.73±1.37,P<0.001) images,and showed lower noise (10.51±3.53) than the FBP(4.10±3.92,P<0.001),AIDR 3D (15.72±2.41,P=0.032),and FIRST (17.20±3.82,P<0.001) images.SNR and CNR showed no significant differences between FIRST and AIDR 3D images (all P>0.05).DLR images [4(4,4)] obtained higher score than FPB [1(1,1),P<0.001],AIDR3D[3 (2,3),P=0.029],and FIRST[2 (2,3),P<0.001] images. Conclusion DLR algorithm improved the subjective and objective quality of the contrast-enhanced CT image of the biliary system.

Assessing Liver Function by T1 Maps on Gd-EOB-DTPA-Enhanced MRI for up to 50 Min in Rat Models of Liver Fibrosis: A Longer Hepatobiliary Time Period may Help.

Objectives To investigate whether a longer time period of gadolinium ethoxybenzyl diethylenetriaminepen-taacetic acid (Gd-EOB-DTPA)-enhanced T1 mapping scanning, as well as dynamic contrast-enhanced (DCE) and multiple hepatobiliary phase magnetic resonance imaging (MRI) have the potential to provide information about liver function in rats with liver fibrosis. Methods Forty rats were divided into the carbon tetrachloride-induced hepatic injury groups [carbon tetrachloride for four (n=14), eight (n=8), or twelve (n=8) weeks] and the control group (n=10). Gd-EOB-DTPA-enhanced MRI was performed including T1-mapping (delayed to 50 min), DCE, and multiple hepatobiliary phases. Indocyanine green retention rate at 15 min (ICG-R15) was determined. Parameters such as T1 reduction rate (ΔT1), elimination half-life of ΔT1 (TΔT1 1/2), relative enhancement (RE), time to maximum RE (Tmax), and perfusion parameters were calculated. Pearson correlation analysis was used for correlation analysis between ICG-R15 and each MRI indices. Results ΔT1 at 30, 40, and 50 min showed significant positive correlations with ICG-R15 ( r=0.784, 0.653, 0.757, P=0.007, 0.041, 0.030). TΔT1 1/2 showed a significant positive correlation with ICG-R15 (r=0.685, P=0.029). Tmaxshowed a significant positive correlation with ICG-R15 (r=0.532, P=0.019). Conclusions ΔT1 in the late hepatobiliary phase and T ΔT1 1/2 exhibited moderate correlations with liver function. The longer time period of Gd-EOB-DTPA-enhanced T1 mapping scanning, as well as DCE and multiple hepatobiliary phases, may be of some value for estimating liver function in rats with liver fibrosis.

[Correlation of Intravoxel Incoherent Motion-derived Parameters with Computer Tomography Perfusion Parameters in Insulinoma].

Objective To prospectively evaluate the correlation between intravoxel incoherent motion (IVIM)-derived parameters and CT perfusion parameters as well as the pathological grade in insulinoma. Methods A total of 55 patients with suspected insulinoma undergoing IVIM and CT perfusion scans were prospectively enrolled. The images were post-processed to obtain IVIM parameters including apparent diffusion coefficient (ADC),diffusion (D),perfusion correlated diffusion (D*),and f,and CT perfusion parameters including blood flow (BF),blood volume (BV),and permeability (PM). The pathological specimens were stained to obtain pathological parameters including the grading,ki-67 index,and the mitotic count. The IVIM derived parameters of normal pancreas including head,body,and tail as well as that of the pancreatic insulinoma were compared. The correlation between IVIM parameters and CT perfusion parameters as well as the pathological parameters was analyzed. Results ADC and D values of pancreatic tail were significantly lower than those of the pancreatic head and neck (all P<0.001). There were significant differences in all IVIM parameters between insulinoma and normal pancreas (all P<0.001). The ADC and f value of the normal pancreas was positively correlated with BF (r=0.437,P=0.003;r=0.357,P=0.010). There is no correlation between the remaining IVIM parameters and the CT perfusion parameters as well as between IVIM parameters and pathological parameters (all P>0.05). Conclusions IVIM parameters differ at different anatomical parts of normal pancreas. IVIM parameters can distinguish normal pancreatic parenchyma from insulinoma. The ADC value is weakly correlated with BF.

Value of Texture Analysis on Gadoxetic Acid-enhanced MR for Detecting Liver Fibrosis in a Rat Model.

Objective To explore the ability of texture analysis of gadoxetic acid-enhanced magnetic resonance imaging (MRI) T1 mapping images, as well as T1-weighted (T1W), T2-weighted (T2W) and apparent diffusion coefficient (ADC) maps for distinguishing between varying degrees of hepatic fibrosis in an experimental rat model.Methods Liver fibrosis in rats was induced by carbon tetrachloride intraperitoneal injection for 4-12 weeks (n=30). In the control group (n=10) normal saline was applied. The MRI protocol contained T2W, diffusion weighted imaging, pre-and post-contrast image series of T1W and T1 mapping images. METAVIR score was used to grade liver fibrosis as normal (F0), mild fibrosis (F1-2), and advanced fibrosis (F3-4). Texture parameters including mean gray-level intensity (Mean), standard deviation (SD), Entropy, mean of positive pixels (MPP), Skewness, and Kurtosis were obtained. Nonparametric Mann-Whitney U test was used to compare the average value of each texture parameter in each sequence for assessing the difference between F0 and F≥1 as well as F0-2 and F3-4. Receiver operating characteristic (ROC) curves were obtained to assess the diagnosing accuracy of the parameters for differentiating no liver fibrosis from liver fibrosis and rats with liver fibrosis grading F0-2 from those with grading F3-4. The area under ROC curve (AUC) was calculated to evaluate the diagnostic efficiency of texture parameters.Results Finally, 20 rats completed MR T1 mapping image scan. The pathologic staging of these 20 rats was no fibrosis (F0, n=6), mild fibrosis (F1-2, n=5) and advanced fibrosis (F3-4, n=9). On pre-contrast T1 mapping image, Entropy was seen to be statistically significant higher in the F≥1 group than that in the F0 group at each spatial scaling factor (SSF) setting (P=0.015, 0.015, 0.015, 0.013, 0.015 and 0.018 respectively to SSF=0, 2, 3, 4, 5, 6), and Mean of the F≥1 rats was statistically significant higher than that of the F0 rats at SSF 4, 5, 6 (P=0.004, 0.006, and 0.013, respectively). Entropy and Mean showed a moderate diagnostic performance in most SSF settings of T1 mapping pre-contrast images for differentiation of normal liver from liver fibrosis.Conclusions Certain texture features of gadoxetic acid-enhanced MR images, especially the Entropy of non-contrast T1 mapping image, was found to be a useful biomarker for the diagnosis of liver fibrosis.

[Gadolinium Ethoxybenzyl Diethylene-triamine-pentaacetic-acid-enhanced Magnetic Resonance Imaging Perfusion and Multiple Hepatobiliary-phase Imaging for Quantitative Assessment of Liver Fibrosis in Rat Models].

Objective To investigate the value of gadolinium ethoxybenzyl diethylene-triamine-pentaacetic-acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) in detecting different stages of liver fibrosis in rats.Methods Rat models of liver fibrosis were induced by carbon tetrachloride intraperitoneal injection for 4 - 12 weeks (n=45). The control group was applied with 0.9% saline (n=15). The MRI protocol contained both dynamic contrast-enhanced sequence (60 continuous scans within 3 minutes,including three pre-contrast measurements) and multiple hepatobiliary-phase acquisitions (every 5 minutes after contrast injection,60 minutes in total). METAVIR score was used to grade liver fibrosis:normal (F0),mild fibrosis (F1 - F2),and advanced fibrosis (F3 - F4). Liver perfusion parameters [transfer constant (K trans),extravascular extracellular volume fraction (Ve),initial area under curve (iAUC),maximum relative enhancement (REmax),and time of maximum RE (Tmax)] as well as hepatobiliary-phase parameters [RE at different time point,the decrease of RE (REchange=RE3 min - RE60 min),and elimination half-life of RE (TRE1/2)] were measured and compared with ANOVA analysis and Spearman rank correlation.Results Thirty-one rats completed MRI exams and were then divided into normal (n=10),mild fibrosis (n=10),and advanced fibrosis (n=11) groups. K trans,Ve and iAUC decreased as liver fibrosis progressed (r=-0.631,P=0.002;r=-0.503,P=0.017;r=-0.446,P=0.037). K trans and Ve showed significant differences among three groups(F=7.011,P=0.005;F=4.656,P=0.023). K trans and Ve were significantly lower in advanced fibrosis group than in normal group (P=0.001,P=0.009). There were statistical significant differences of Tmax,TRE1/2 and REchange among groups(F=6.633,P=0.005;F=5.493,P=0.010;F=5.343,P=0.014). Compared to normal and mild fibrosis groups,advanced fibrosis group had significantly longer Tmax and TRE1/2 (P=0.005,P=0.004;P=0.008,P=0.008)and significantly lower REchange(P=0.007,P=0.012).Conclusion Perfusion and multi-hepatobiliary-phase parameters such as K trans,Ve,Tmax, TREI/2 and REchange obtained from Gd-EOB-DTPA-enhanced MRI,may be valuable for detecting and staging liver fibrosis.

Multiple solid pancreatic lesions: Prevalence and features of non-malignancies on dynamic enhanced CT.

OBJECTIVE: To determine the prevalence of multiple solid pancreatic lesions on dynamic enhanced CT performed for suspected pancreatic diseases, and to identify CT features of non-malignancies. METHODS: We investigated 8096 consecutive patients who underwent dynamic enhanced CT pancreas protocol at a tertiary center over 40 months. The final clinical /pathological diagnosis served as reference standard. The diagnostic accuracy of dynamic enhanced CT for non-malignancies was calculated. A univariate and multivariate analysis was conducted to identify features that predict non-malignancies. RESULTS: Multiple solid pancreatic lesions were identified in 121 patients. The prevalence of non-malignancies was 19.8% (24/121). The most common non-malignancy was autoimmune pancreatitis (n = 21; 17.4%). Common lesions with malignant potential included neuroendocrine neoplasia (n = 62; 51.2%), ductal adenocarcinoma (n = 15; 12.4%), metastasis (n = 9; 7.4%), and lymphoma (n = 7; 5.8%). Dynamic enhanced CT had a sensitivity of 79.2% and a specificity of 92.8% for diagnosing non-malignancies. Elevated serum IgG4 level (p < 0.001), hypo-enhancement in arterial phase (p = 0.001), hyper-enhancement in equilibrium phase (p = 0.009) and location in both proximal and distal pancreas (p = 0.036) were predictors of non-malignancies, whereas pancreatic duct morphology and vascular invasion status were not. CONCLUSION: Multiple solid pancreatic lesions were rare, with a wide spectrum. Dynamic enhanced CT provides clues for identifying non-malignancies.