Dual-layer spectral detector CT for contrast agent concentration, dose and injection rate reduction: Utility in imaging of the superior mesenteric artery.

PURPOSE: To investigate the feasibility of contrast agent and injection rate reduction for dual-layer spectral detector computed tomography (SDCT) imaging of the superior mesenteric artery (SMA) using virtual monochromatic image (VMI). METHODS: A total of 102 patients who underwent abdominal arterial phase-enhanced SDCT examination due to suspected abdominal diseases were prospectively selected and divided into control group, low concentration/dose groups (groups 370-0.7, 300-1.0, and 300-0.9) and low injection rate groups (groups 2-370 and 2-350). Compared with the control group, low concentration/dose groups and low injection rate groups lowered the concentration/dose or injection rate of the contrast agent to varying degrees. The raw data obtained in each group were reconstructed using hybrid-iterative reconstruction and projection spatial-spectral reconstruction algorithm. The image quality of the SMA in conventional images (CI) and in VMIs40-140 kiloelectron volt (keV) (interval: 10 keV) during the arterial phase was analyzed. Multiplanar reformation images and volume rendering images of the SMA were reconstructed. Image quality objective evaluation indexes included the CT values, contrast-to-noise ratio, signal-to-noise ratio, and diameter of the SMA. The diameter of the SMA was determined by the CT values profile curve and its full width at half maximum. Two doctors independently evaluated the subjective image quality of multiplanar reformation coronal images and volume rendering images according to a 5-point scale. Repeated analysis of variance and Friedman test were used to compare the differences in the objective evaluation indexes and subjective scores between VMIs and CI in the same group. The Dunnett's t-test or Dunnett's T3 test and Kruskal-Wallis H-test were used to compare the differences in the objective evaluation indexes and subjective scores between the experimental and control groups. RESULTS: VMIs of the SMA in each group had the best image quality at 60 keV, and VMI60 keV in each group were better than their respective CI to varying degrees. Although the objective (CT values, contrast-to-noise ratio, and signal-to-noise ratio) and subjective (subjective scores) indexes of CI in the low concentration/dose groups and low injection rate groups were lower than those of CI in the control group to varying degrees, these indexes of VMI60 keV in the low concentration/dose groups and group 2-370 were equal to or even better than the CI in the control group. CONCLUSIONS: VMI60 keV using SDCT could effectively reduce the contrast agent load while providing equivalent or better SMA image quality compared with CI obtained using a conventional contrast agent protocol. When the injection rate was lowered to 2.0 ml/s for a high-concentration contrast agent (370 mgI/ml), the SMA image quality at VMI60 keV was comparable with that of the CI in the control group.

Liver Fibrosis Staging with Gadolinium Ethoxybenzyl Diethylenetriamine Penta-Acetic Acid-enhanced: A Systematic Review and Meta-analysis.

OBJECTIVE: While liver biopsy is the golden standard for liver-fibrosis diagnosis, it is also invasive and has many limitations. Non-invasive techniques such as Magnetic Resonance Imaging (MRI) need to be further developed for liver fibrosis staging. This study aimed to evaluate the diagnostic accuracy of Gadolinium Ethoxybenzyl Diethylenetriamine Penta-acetic Acid (Gd-EOBDTPA)- enhanced MRI for liver fibrosis through systematic review and meta-analysis. METHODS: This study comprehensively searched relevant article in PubMed, Embase, and the Cochrane Library published from 2004 to 2018 to find studies analyzing the diagnostic accuracy of Gd-EOB-DTPA-enhanced MRI for liver fibrosis. Two reviewers independently screened the retrieved articles, extracted the required data from the included studies, and evaluated the methodological quality of the studies. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and Summary Receiver Operating Characteristics (SROC) curve were assessed. RESULTS: This study finally included 16 studies (n = 1,599) and selected a random-effects model based on the results of the I2 statistic to combine them. The areas under the SROC curve for the detection of F1 or greater, F2 or greater, F3 or greater, or F4 liver fibrosis were 0.8669, 0.8399, 0.8481, and 0.8858, respectively. CONCLUSION: Gd-EOB-DTPA-enhanced MRI showed a good diagnostic performance for staging liver fibrosis, especially for F4 liver fibrosis.

Quantitative analysis of susceptibility-weighted magnetic resonance imaging in chronic hepatitis in rats.

PURPOSE: To assess the value of susceptibility-weighted imaging (SWI) for staging of liver fibrosis (F), necroinflammatory activity (A), and steatosis (S) of chronic hepatitis. METHODS: 100 Sprague-Dawley (SD) male rats were randomly divided into a chronic hepatitis model group (n = 88) and a control group (n = 12). The chronic hepatitis model rats were induced by intraperitoneal injection of 40% (v/v) of carbon tetrachloride (CCl4) diluted in olive oil. All rats were examined by magnetic resonance imaging (MRI) and then killed immediately to detect pathologic staging as liver fibrosis (F), necroinflammatory activity (A), and steatosis (S). Liver-to-muscle signal intensity ratios (SIRs) of SWI were analyzed and associated with histopathologic findings. RESULTS: There were ultimately 11 normal control rats and 60 chronic hepatitis model rats. Statistical data were as follows: F0 (n = 11), F1 (n = 18), F2 (n = 16), F3 (n = 13), F4 (n = 13); A0 (n = 11), A1 (n = 29), A2 (n = 21), A3 (n = 10); S0 (n = 11), S1 (n = 12), S2 (n = 12), S3 (n = 18), and S4 (n = 18). The liver-to-muscle SIR of the SWI was related to hepatic fibrosis (P < 0.05) and liver steatosis (P < 0.05) but not to necroinflammatory activity (P > 0.05). By partial correlation analysis, a significant negative correlation was shown between the liver-to-muscle SIR and staging of liver fibrosis (r = -0.68, P < 0.05) as well as a low correlation with liver steatosis (r = 0.30, P < 0.05). Except for F0-F1 and F1-F2, there were statistical differences between each of the stages of hepatic fibrosis (P < 0.05), with an area under the ROC of 0.87 for F3 or above and of 0.96 for F4. CONCLUSION: SWI can be a reliable method for staging hepatic fibrosis.