Non-contrast-enhanced MR angiography of left gastric vein in patients with gastroesophageal varices: morphology and blood supply analysis.

OBJECTIVES: To investigate the feasibility of non-contrast-enhanced MR angiography (NCE-MRA) in evaluating the morphology and blood supply of left gastric vein (LGV) in patients with gastroesophageal varices. METHODS: Between March 2021 and October 2022, patients with gastroesophageal varices and who underwent NCE-MRA were retrospectively reviewed. In order to evaluate the blood supply of LGV, superior mesenteric vein (SMV) and splenic vein (SV) were visualized separately by using inflow-sensitive inversion recovery sequence. Two radiologists independently assessed the image quality, determined the origination and the blood supply of LGV, and measured the diameter of LGV. The origination and diameter of LGV were compared between NCE-MRA and contrast-enhanced CT. Differences in blood supply were compared between LGVs with different originations. RESULTS: A total of 53 patients were enrolled in this study and the image quality was categorized as good or excellent in 52 patients. No significant differences were observed in visualizing the origination and the diameter of LGV between NCE-MRA and contrast-enhanced CT (p > .05). The blood supply of LGV was related to its origination (p < .001). Most LGVs with SV origination were supplied by SV. If LGV was originated from the portal vein (PV), about 70% of them were supplied by both SV and SMV. Compared with LGVs with SV origination, LGVs with PV origination showed more chance to receive blood from SMV (p < .001). CONCLUSION: Non-contrast-enhanced MR angiography appears to be a reliable technique in evaluating the morphology and blood supply of LGV in patients with gastroesophageal varices. CLINICAL RELEVANCE STATEMENT: Non-contrast-enhanced MR angiography provides valuable information for the management of gastroesophageal varices. Especially, it benefits patients with renal insufficiency. KEY POINTS: • Non-contrast-enhanced MR angiography using inflow-sensitive inversion recovery technique can be used for evaluating not only morphology as CT but also blood supply of left gastric vein. • The blood supply of left gastric vein is related to its origination and left gastric vein with portal vein origination shows more chance to receive blood from superior mesenteric vein.

Multiparametric MRI-Based Radiomic Signature for Preoperative Evaluation of Overall Survival in Intrahepatic Cholangiocarcinoma After Partial Hepatectomy.

BACKGROUND: The clinical outcomes of patients with intrahepatic cholangiocarcinoma (ICC) after partial hepatectomy remain suboptimal. Identifying patients with poor outcomes before surgery is urgently required. PURPOSE: To develop a multiparametric magnetic resonance imaging (MRI)-based radiomic signature to evaluate overall survival (OS) preoperatively and to investigate its incremental value for disease stratification. STUDY TYPE: Retrospective. SUBJECTS: One hundred and sixty-three patients with pathologically defined ICC, divided into training (N = 115) and validation sets (N = 48). SEQUENCE: Three-dimensional T1-weighted gradient-echo sequence with and without contrast agent, T2-weighted fast spin-echo sequence, and diffusion-weighted imaging with single-shot echo-planar sequence at 1.5 T or 3.0 T. ASSESSMENT: OS was defined as the time from the date of surgery to death or last contact. The radiomic signature was built based on the least absolute shrinkage and selection operator regression model. A clinicopathologic-radiographic (CPR) model and a combined model integrating radiomic signature with CPR factors were developed with multivariable Cox regression models. STATISTICAL TESTS: Harrell's concordance index (C-index) was used to compare the discrimination of different models. Net reclassification index (NRI) and integrated discrimination improvement (IDI) were used to quantify the improvement of prognostic accuracy after adding radiomic signature. RESULTS: The high-risk patients of death defined by the radiomic signature showed significantly lower OS compared with low-risk patients in validation set (3-year OS 17.1% vs. 56.4%, P < 0.001). Integrating radiomic signature into tumor, node, and metastasis (TNM) staging system significantly improved the prognostic accuracy compared with TNM stage alone (validation set C-index 0.745 vs. 0.649, P = 0.039, NRI improvement 39.9%-43.8%, IDI improvement 16.1%-19.4%). The radiomic signature showed no significant difference of C-index with postoperative CPR model (validation set, 0.698 vs. 0.674, P = 0.752). Incorporating the radiomic signature into CPR model significantly improved prognostic accuracy (NRI improvement 32.5%-34.3%, IDI improvement 8.1%-12.9%). DATA CONCLUSION: Multiparametric MRI-based radiomic signature is a potential biomarker for preoperative prognostic evaluation of ICC patients. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY: Stage 4.

Volumetric Apparent Diffusion Coefficient Histogram Analysis in Differentiating Intrahepatic Mass-Forming Cholangiocarcinoma From Hepatocellular Carcinoma.

BACKGROUND: Accurate differentiation between intrahepatic mass-forming cholangiocarcinoma (IMCC) and hepatocellular carcinoma (HCC) is needed because treatment and prognosis differ significantly. PURPOSE: To explore whether volumetric apparent diffusion coefficient (ADC) histogram analysis can provide additional value to dynamic enhanced MRI in differentiating IMCC from HCC. STUDY TYPE: Retrospective. POPULATION: In all, 131 patients with pathologically proven IMCC (n = 33) or HCC (n = 98). FIELD STRENGTH/SEQUENCE: 3.0T MRI/conventional T1 -weighted imaging (T1 WI), T2 WI, and diffusion-weighted imaging (DWI) with b value of 800 sec/mm2 , dynamic enhanced MRI with gadobenate dimeglumine. ASSESSMENT: Dynamic enhanced MR images were analyzed by two independent reviewers using a five-point scale to determine the diagnosis. Volumetric ADC assessments were performed independently by two radiologists to obtain different histogram parameters for each lesion. Quantitative histogram parameters were compared between the IMCC group and HCC group. Diagnostic performance of dynamic enhanced MRI, volumetric ADC histogram analysis, and the combination of both were analyzed. STATISTICAL TESTS: Intraclass correlation coefficient (ICC) analysis, independent Student's t-test, or Mann-Whitney U-test, receiver operator characteristic (ROC) curves analysis, and McNemar test. RESULTS: The sensitivity and specificity for dynamic enhanced MRI to differentiate IMCC from HCC were 82.1% and 82.6%, respectively. For all volumetric ADC histogram parameters, the 75th percentile ADC (ADC75% ) had the highest AUC (0.791) in differentiating IMCC from HCC, with sensitivity and specificity of 69.7% and 77.6%, respectively. When combining dynamic enhanced MRI with ADC75% , the sensitivity and specificity were 82.1% and 91.9%, respectively. Compared to dynamic enhanced MRI alone, the specificity for combined dynamic enhanced MRI and ADC75% was significantly increased (P = 0.008). DATA CONCLUSION: Volumetric ADC histogram analysis provides additional value to dynamic enhanced MRI in differentiating IMCC from HCC. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:975-983.

Did low tube voltage CT combined with low contrast media burden protocols accomplish the goal of "double low" for patients? An overview of applications in vessels and abdominal parenchymal organs over the past 5 years.

BACKGROUND: Imaging communities have already reached a consensus that the radiation dose of computed tomography (CT) should be reduced as much as reasonably achievable to lower population risks. Increasing attention is being paid to iodinated contrast media (CM) induced nephrotoxicity (CIN); a decrease in the intake of iodinated CM is required by increasingly more radiologists. Theoretically, the radiation dose varies with the tube current time and square of the tube voltage, with higher iodine contrast at low photon energies (Huda et al. [2000] Radiology, 21 7, 430-435).The use of low tube voltage is a promising strategy to reduce both the radiation dose and CM burden. The term 'double low' has been coined to describe scanning protocols that reduce radiation dose and iodine intake synchronously. These protocols are becoming increasingly popular in the clinical setting. PURPOSE: The aim of this review was to describe all original studies using the 'double low' strategy in the last 5 years. METHODS: We searched an online electronic database (PubMed) from January 2011 to December 2015 for original studies published on the relationship of low tube voltage with low radiation dose and low iodine contrast media burden in patients undergoing CT scans. Studies that failed to reduce radiation dose or iodine CM burden were excluded in this study. RESULTS: Thirty-seven studies aimed at reducing radiation dose using low tube voltage combined with iodine CM reduced protocols were included in this study. Most studies evaluated conditions associated with arteries. Four were cerebral and neck computed tomography angiography (CTA) studies, 15 were pulmonary CTA (pCTA) and coronary CTA (cCTA) studies, one concerned myocardial perfusion, five studies focused on the thoracic and abdominal aorta, and one investigated renal arteries. Three studies consisted of CT venography (CTV) of the pelvis and lower extremities. Six publications examined the liver, and two focused on the kidney. CONCLUSION: Overall, this review demonstrates that the low tube voltage CT protocol is a powerful tool to reduce the radiation dose in CTA, especially with pCTA and cCTA.

Chemical Shift-Encoded Sequence (IDEAL-IQ) and Amide Proton Transfer (APT) MRI for Prediction of Histopathological Factors of Rectal Cancer.

To investigate whether parameters from IDEAL-IQ/amide proton transfer MRI (APTWI) could help predict histopathological factors of rectal cancer. Preoperative IDEAL-IQ and APTWI sequences of 67 patients with rectal cancer were retrospectively analyzed. The intra-tumoral proton density fat fraction (PDFF), R2* and magnetization transfer ratio asymmetry (MTRasym (3.5 ppm)) were measured according to the histopathological factors of rectal cancer. The relationship between MR parameters and histopathological factors were analyzed, along with diagnostic performance of MR parameters. PDFF, R2* and MTRasym (3.5 ppm) were statistically different between T1+T2/T3+T4 stages, non-metastatic/metastatic lymph nodes, lower/higher tumor grade and negative/positive status of MRF and EMVI (p < 0.001 for PDFF, p = 0.000-0.015 for R2* and p = 0.000-0.006 for MTRasym (3.5 ppm)). There were positive correlations between the above parameters and the histopathological features of rectal cancer (r = 0.464-0.723 for PDFF (p < 0.001), 0.299-0.651 for R2* (p = 0.000-0.014), and 0.337-0.667 for MTRasym (3.5 ppm) (p = 0.000-0.005)). MTRasym (3.5 ppm) correlated moderately and mildly with PDFF (r = 0.563, p < 0.001) and R2* (r = 0.335, p = 0.006), respectively. PDFF provided a significantly higher diagnostic ability than MTRasym (3.5 ppm) for distinguishing metastatic from non-metastatic lymph nodes (z = 2.407, p = 0.0161). No significant differences were found in MR parameters for distinguishing other histopathological features (p > 0.05). IDEAL-IQ and APTWI were associated with histopathological factors of rectal cancer, and might serve as non-invasive biomarkers for characterizing rectal cancer.

DWI-based radiomic signature: potential role for individualized adjuvant chemotherapy in intrahepatic cholangiocarcinoma after partial hepatectomy.

OBJECTIVES: To develop a diffusion-weighted imaging (DWI) based radiomic signature for predicting early recurrence (ER) (i.e., recurrence within 1 year after surgery), and to explore the potential value for individualized adjuvant chemotherapy. METHODS: A total of 124 patients with intrahepatic cholangiocarcinoma (ICC) were randomly divided into the training (n = 87) and the validation set (n = 37). Radiomic signature was built using radiomic features extracted from DWI with random forest. An integrated radiomic nomogram was constructed with multivariate logistic regression analysis to demonstrate the incremental value of the radiomic signature beyond clinicopathological-radiographic factors. A clinicopathological-radiographic (CPR) model was constructed as a reference. RESULTS: The radiomic signature showed a comparable discrimination performance for predicting ER to CPR model in the validation set (AUC, 0.753 vs. 0.621, p = 0.274). Integrating the radiomic signature with clinicopathological-radiographic factors further improved prediction performance compared with CPR model, with an AUC of 0.821 (95%CI 0.684-0.959) in the validation set (p = 0.01). The radiomic signature succeeded to stratify patients into distinct survival outcomes according to their risk index of ER, and remained an independent prognostic factor in multivariable analysis (disease-free survival (DFS), p < 0.0001; overall survival (OS), p = 0.029). Furthermore, adjuvant chemotherapy improved prognosis in high-risk patients defined by the radiomic signature (DFS, p = 0.029; OS, p = 0.088) and defined by the nomogram (DFS, p = 0.031; OS, p = 0.023), whereas poor chemotherapy efficacy was detected in low-risk patients. CONCLUSIONS: The preoperative DWI-based radiomic signature could improve prognostic prediction and help to identify ICC patients who may benefit from postoperative adjuvant chemotherapy.

Differentiation of hepatocellular carcinoma from intrahepatic cholangiocarcinoma and combined hepatocellular-cholangiocarcinoma in high-risk patients matched to MR field strength: diagnostic performance of LI-RADS version 2018.

PURPOSE: To eliminate the effects of field strength in determining the diagnostic performance of the LI-RADS version 2018 (LI-RADS v2018) in differentiating hepatocellular carcinoma (HCC) from non-HCC primary liver malignancy in high-risk patients. METHODS: Patients who were pathologically confirmed intrahepatic cholangiocarcinoma (iCCA) or combined hepatocellular-cholangiocarcinoma (cHCC-CCA) were retrospectively reviewed. Patients with HCC were matched to the iCCA or cHCC-CCA patients on age, tumor size, MR scanner, and number of tumors. Two readers independently evaluated the lesions according to LI-RADS v2018. Diagnostic performance of LI-RADS v2018 in differentiating HCC from non-HCC primary liver malignancy were analyzed. RESULTS: A total of 198 patients with 204 lesions (102 HCCs, 78 iCCAs, and 24 cHCC-CCAs) were enrolled. The sensitivity and specificity of LR-5 or LR-TIV (definitely due to HCC) in diagnosing HCC were 68.63% and 85.29%, respectively. LR-M or LR-TIV (may be due to non-HCC malignancy) had a sensitivity of 72.55% and a specificity of 86.27% in diagnosing non-HCC malignancy. The sensitivity of LR-M or LR-TIV (may be due to non-HCC malignancy) for iCCA and cHCC-CCA was 82.05% and 41.67%, respectively. Nearly half (11/24, 45.83%) of cHCC-CCAs were categorized as LR-5. Three tesla MR showed higher sensitivity than 1.5 T in diagnosing HCC (80.00% vs 57.69%, P = 0.015). CONCLUSION: When the effect of field strength was eliminated, LI-RADS v2018 demonstrated high specificity but suboptimal sensitivity in distinguishing HCC from non-HCC primary liver carcinomas. Most iCCAs were categorized as LR-M or LR-TIV (may be due to non-HCC malignancy). However, nearly half of cHCC-CCAs were assigned as LR-5.

Hemodynamic study of unenhanced magnetic resonance angiography using spatial labeling with multiple inversion pulses sequence: a phantom study.

BACKGROUND: This study sought to explore the functional relationship between displayed vascular length and blood suppression inversion time (BSP TI) and flow velocity in a phantom, and to provide a theoretical basis for quantitatively assessing vascular hemodynamic responses using unenhanced magnetic resonance angiography (MRA) and spatial labeling with multiple inversion pulses sequence (SLEEK). METHODS: A polyethylene catheter was laid in a long rectangular container filled with pork fat. The entrance of the catheter into the container was connected to a high-pressure syringe filled with normal saline. The high-pressure injector flow rates were set at 0.0, 0.2, 0.4, 0.8, 1.2, 1.6, 2.0, and 2.4 mL/s. SLEEK was performed 19 times for each flow rate with parameter BSP TI values of 50, 75, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1,000, 1,100, 1,200, 1,300, 1,400, 1,600, and 1,800 ms. Maximum intensity projection was employed to reconstruct all SLEEK original images to determine the measurements of the displayed vascular lengths. A regression analysis was undertaken to assess the relationship between the displayed vascular lengths and BSP TI values for each flow rate, and to assess the relationship between the displayed vascular lengths and flow rates at each BSP TI. RESULTS: The displayed vascular length had a linear relationship with BSP TI for each flow rate (P<0.05) (R2=0.754, 0.941, 0.988, 0.988, 0.977, 0.966, and 0.982 for flow rates of 0.0, 0.2, 0.4, 0.8, 1.2, 1.6, and 2.0 mL/s, respectively). The displayed vascular length also had a linear relationship with flow rate for each BSP TI value (P<0.05) (R2 =0.914, 0.912, 0.834, 0.989, 0.980, 0.996, 0.992, 0.960, 0.975, 0.979, 0.982, 0.981, 0.976, and 0.993 for BSP TI 50, 75, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1,000, and 1,100 ms, respectively). No significant linear relationship was found between displayed vascular length and flow rate when the BSP TI value was 1,200 ms (P>0.05). CONCLUSIONS: Vascular displayed length has a linear relationship to BSP TI for flow ranges from 0.0 to 2.0 mL/s. Vascular displayed length has a linear relationship to flow rate for BSP TI values of 50 to 1,100 ms. Flow rate can be assessed in relation to vascular displayed length.

Gallbladder carcinoma: an initial clinical experience of reduced field-of-view diffusion-weighted MRI.

BACKGROUND: The purpose of this study is to compare the diagnostic value, imaging quality and apparent diffusion coefficient (ADC) value of reduced field-of-view diffusion-weight imaging (r-FOV DWI) and full field-of-view diffusion-weight imaging (f-FOV DWI) in patients with gallbladder carcinoma and other lesions of gallbladder. METHODS: Two hundred ninety-six patients with gallbladder diseases underwent both r-FOV DWI and f-FOV DWI on a 3.0 T MRI scanner. Two radiologists assessed subjective image quality parameters independently. The Wilcoxon signed-rank test was used to compare subjective qualitative image score. Objective quality values and the mean ADC values were analyzed by paired t-test. The correlation between pathological results and mean ADC value were estimated using Spearman rank correlation analysis. RESULTS: The CNR value (10.23 ± 2.92) and image quality score (13.84 ± 1.07) of r-FOV DWI were significantly higher than those of f-FOV DWI (5.24 ± 1.29 P<0.001; 10.41 ± 1.11 P<0.001). There was no significant difference between mean ADC values of the two DWI sequences for all three groups (Group 1, chronic cholecystitis; Group 2, benign lesions of gallbladder; Group 3, gallbladder carcinoma. P = 0.239, 0.974 and 0.226 respectively). For both DWI sequences, the mean ADC values were the highest in the group of cholecystitis and the lowest in the group of gallbladder carcinoma (2.49 ± 0.14 vs 1.49 ± 0.12; 2.50 ± 0.14 vs 1.50 ± 0.13, for f-FOV and r-FOV respectively), the differences among groups were statistically significant (P<0.01). The mean ADC values for both DWI sequences were negatively correlated with the group number, which increased with the malignant tendency of lesions (r = - 0.892, P<0.01; r = - 0.913, P<0.01 for f-FOV and r-FOV respectively). CONCLUSION: Reduced Field-of-view Diffusion-weighted MRI is a good tool to diagnosis the gallbladder carcinoma, with better image quality and without affecting ADC values.

Visceral Adiposity and High Intramuscular Fat Deposition Independently Predict Critical Illness in Patients with SARS-CoV-2.

OBJECTIVE: This study aimed to assess the association between adipose tissue distribution and severity of clinical course in patients with severe acute respiratory syndrome coronavirus 2. METHODS: For this retrospective study, 143 hospitalized patients with confirmed coronavirus disease 2019 (COVID-19) who underwent an unenhanced abdominal computed tomography (CT) scan between January 1, 2020, and March 30, 2020, were included. Univariate and multivariate logistic regression analyses were performed to identify the risk factors associated with the severity of COVID-19 infection. RESULTS: There were 45 patients who were identified as critically ill. High visceral to subcutaneous adipose tissue area ratio (called visceral adiposity) (odds ratio: 2.47; 95% CI: 1.05-5.98, P = 0.040) and low mean attenuation of skeletal muscle (called high intramuscular fat [IMF] deposition) (odds ratio: 11.90; 95% CI: 4.50-36.14; P < 0.001) were independent risk factors for critical illness. Furthermore, visceral adiposity or high IMF deposition increased the risk of mechanical ventilation (P = 0.013, P < 0.001, respectively). High IMF deposition increased the risk of death (P = 0.012). CONCLUSIONS: COVID-19 patients with visceral adiposity or high IMF deposition have higher risk for critical illness. Therefore, patients with abdominal obesity should be monitored more carefully when hospitalized.

Apparent diffusion coefficient-based histogram analysis differentiates histological subtypes of periampullary adenocarcinoma.

BACKGROUND: For periampullary adenocarcinoma, the histological subtype is a better prognostic predictor than the site of tumor origin. Intestinal-type periampullary adenocarcinoma (IPAC) is reported to have a better prognosis than the pan-creatobiliary-type periampullary adenocarcinoma (PPAC). However, the classification of histological subtypes is difficult to determine before surgery. Apparent diffusion coefficient (ADC) histogram analysis is a noninvasive, non-enhanced method with high reproducibility that could help differentiate the two subtypes. AIM: To investigate whether volumetric ADC histogram analysis is helpful for distinguishing IPAC from PPAC. METHODS: Between January 2015 and October 2018, 476 consecutive patients who were suspected of having a periampullary tumor and underwent magnetic resonance imaging (MRI) were reviewed in this retrospective study. Only patients who underwent MRI at 3.0 T with different diffusion-weighted images (b-values = 800 and 1000 s/mm2) and who were confirmed with a periampullary adenocarcinoma were further analyzed. Then, the mean, 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles of ADC values and ADCmin, ADCmax, kurtosis, skewness, and entropy were obtained from the volumetric histogram analysis. Comparisons were made by an independent Student's t-test or Mann-Whitney U test. Multiple-class receiver operating characteristic curve analysis was performed to determine and compare the diagnostic value of each significant parameter. RESULTS: In total, 40 patients with histopathologically confirmed IPAC (n = 17) or PPAC (n = 23) were enrolled. The mean, 5th, 25th, 50th, 75th, 90th, and 95th percentiles and ADCmax derived from ADC1000 were significantly lower in the PPAC group than in the IPAC group (P < 0.05). However, values derived from ADC800 showed no significant difference between the two groups. The 75th percentile of ADC1000 values achieved the highest area under the curve (AUC) for differentiating IPAC from PPAC (AUC = 0.781; sensitivity, 91%; specificity, 59%; cut-off value, 1.50 × 10-3 mm2/s). CONCLUSION: Volumetric ADC histogram analysis at a b-value of 1000 s/mm2 might be helpful for differentiating the histological subtypes of periampullary adenocarcinoma before surgery.

The combination of a reduction in contrast agent dose with low tube voltage and an adaptive statistical iterative reconstruction algorithm in CT enterography: Effects on image quality and radiation dose.

To investigate the subjective and quantitative image quality and radiation exposure of CT enterography (CTE) examination performed at low tube voltage and low concentration of contrast agent with adaptive statistical iterative reconstruction (ASIR) algorithm, compared with conventional CTE.One hundred thirty-seven patients with suspected or proved gastrointestinal diseases underwent contrast enhanced CTE in a multidetector computed tomography (MDCT) scanner. All cases were assigned to 2 groups. Group A (n = 79) underwent CT with low tube voltage based on patient body mass index (BMI) (BMI < 23 kg/m, 80 kVp; BMI ≥ 23 kg/m, 100 kVp) and low concentration of contrast agent (270 mg I/mL), the images were reconstructed with standard filtered back projection (FBP) algorithm and 50% ASIR algorithm. Group B (n = 58) underwent conventional CTE with 120 kVp and 350 mg I/mL contrast agent, the images were reconstructed with FBP algorithm. The computed tomography dose index volume (CTDIvol), dose length product (DLP), effective dose (ED), and total iodine dosage were calculated and compared. The CT values, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of the normal bowel wall, gastrointestinal lesions, and mesenteric vessels were assessed and compared. The subjective image quality was assessed independently and blindly by 2 radiologists using a 5-point Likert scale.The differences of values for CTDIvol (8.64 ±â€Š2.72 vs 11.55 ±â€Š3.95, P < .001), ED (6.34 ±â€Š2.24 vs 8.52 ±â€Š3.02, P < .001), and DLP (422.6 ±â€Š149.40 vs 568.30 ±â€Š213.90, P < .001) were significant between group A and group B, with a reduction of 25.2%, 25.7%, and 25.7% in group A, respectively. The total iodine dosage in group A was reduced by 26.1%. The subjective image quality did not differ between the 2 groups (P > .05) and all image quality scores were greater than or equal to 3 (moderate). Fifty percent ASIR-A group images provided lower image noise, but similar or higher quantitative image quality in comparison with FBP-B group images.Compared with the conventional protocol, CTE performed at low tube voltage, low concentration of contrast agent with 50% ASIR algorithm produce a diagnostically acceptable image quality with a mean ED of 6.34 mSv and a total iodine dose reduction of 26.1%.