Quantitative information from gadobenate dimeglumine-enhanced MRI can predict proliferative subtype of solitary hepatocellular carcinoma: a multicenter retrospective study.

OBJECTIVES: To investigate the value of quantitative parameters derived from gadobenate dimeglumine-enhanced magnetic resonance imaging (MRI) for predicting molecular subtype of hepatocellular carcinoma (HCC) and overall survival. METHODS: This multicenter retrospective study included 218 solitary HCC patients who underwent gadobenate dimeglumine-enhanced MRI. All HCC lesions were resected and pathologically confirmed. The lesion-to-liver contrast enhancement ratio (LLCER) and lesion-to-liver contrast (LLC) were measured in the hepatobiliary phase. Potential risk factors for proliferative HCC were assessed by logistic regression. The ability of LLCER and LLC to predict proliferative HCC was assessed by the receiver operating characteristic (ROC) curve. Prognostic factors were evaluated using the Cox proportional hazards regression model for survival outcomes. RESULTS: LLCER was an independent predictor of proliferative HCC (odds ratio, 0.015; 95% confidence interval [CI], 0.008-0.022; p < 0.001). The area under the ROC curve was 0.812 (95% CI, 0.748-0.877), higher than that of LLC, alpha-fetoprotein > 100 ng/ml, satellite nodules, and rim arterial phase hyperenhancement (all p ≤ 0.001). HCC patients with LLCER < -4.59% had a significantly higher incidence of proliferative HCC than those with the LLCER ≥ -4.59%. During the follow-up period, LLCER was an independent predictor of overall survival (hazard ratio, 0.070; 95% CI, 0.015-0.324; p = 0.001) in HCC patients. CONCLUSIONS: Gadobenate dimeglumine-enhanced quantitative parameter in the hepatobiliary phase can predict the proliferative subtype of solitary HCC with a moderately high accuracy. CLINICAL RELEVANCE STATEMENT: Quantitative information from gadobenate dimeglumine-enhanced MRI can provide crucial information on hepatocellular carcinoma subtypes. It might be valuable to design novel therapeutic strategies, such as targeted therapies or immunotherapy. KEY POINTS: • The lesion-to-liver contrast enhancement ratio (LLCER) is an independent predictor of proliferative hepatocellular carcinoma (HCC). • The ability of LLCER to predict proliferative HCC outperformed lesion-to-liver contrast, alpha-fetoprotein > 100 ng/ml, satellite nodules, and rim arterial phase hyperenhancement. • HCC patients with LLCER < -4.59% had a significantly higher incidence of proliferative HCC than those with the LLCER ≥ -4.59%.

Gd-BOPTA-enhanced hepatobiliary phase MR imaging can predict the prognosis of patients with acute-on-chronic liver failure.

OBJECTIVES: To determine the value of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) from the hepatobiliary phase for predicting poor outcome in acute-on-chronic liver failure (ACLF) patients. METHODS: In this single-center retrospective study, 74 patients diagnosed as ACLF who underwent Gd-BOPTA-enhanced hepatobiliary magnetic resonance imaging were collected. The quantitative liver-spleen contrast ratio (Q-LSC) and the relative enhancement ratio of the biliary system (REB) at the hepatobiliary phase were measured. Cox proportional hazards regression models were used to evaluate prognostic factors. The capacity of the Q-LSC and REB to predict the 90-day outcome was evaluated via receiver operating characteristic (ROC) curve. RESULTS: During the follow-up period, twenty-eight of 74 ACLF patients (38%) had a poor outcome. The Q-LSC and REB were significant predictive factors (hazard ratio [HR] = 0.03 [0.002-0.54], p < 0.05; HR = 0.07 [0.01-0.88], p < 0.05) for prognosis in patients with ACLF. Moreover, the areas under the ROC curves of Q-LSC and REB for predicting poor outcome in patients with ACLF were 0.81 and 0.80, respectively. The most appropriate cutoff values for the Q-LSC and REB were 1.09 and 0.57, respectively. The ACLF patients with the Q-LSC ≤ 1.09 or REB ≤ 0.57 had a low cumulative survival. CONCLUSIONS: Gd-BOPTA-enhanced hepatobiliary phase MR imaging can predict poor outcome in patients with acute-on-chronic liver failure. KEY POINTS: • The quantitative liver-spleen contrast ratio at the hepatobiliary phase was a significant predictive prognostic factor in patients with acute-on-chronic liver failure. • The relative enhancement ratio of the biliary system at the hepatobiliary phase was a significant prognostic factor in patients with acute-on-chronic liver failure. • Gadobenate dimeglumine contrast-enhanced MR imaging from the hepatobiliary phase can predict poor outcome in patients with acute-on-chronic liver failure.

The value of gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase for predicting post-hepatectomy liver failure in HCC patients.

OBJECTIVES: To determine the value of gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase for predicting post-hepatectomy liver failure (PHLF) in patients with hepatocellular carcinoma (HCC). METHODS: Patients with HCC who underwent gadobenate dimeglumine-enhanced hepatobiliary magnetic resonance imaging prior to hepatectomy were collected in two centers. The relative enhancement ratio of the biliary system (REB) and the liver to muscle ratio (LMR) were measured at the hepatobiliary phase. Potential risk factors for PHLF were analyzed by logistic regression. The capacity of the REB and LMR to predict PHLF was analyzed via receiver operating characteristic curve. RESULTS: Of the 221 patients, post-hepatectomy liver failure occurred in 60 patients (27.1%). The REB was an independent risk factor for PHLF (odds ratio [OR] = 0.127 [0.047-0.348], p < 0.001). Although the LMR tended to be associated with PHLF (p = 0.063), it was not an independent risk factor in the multivariable analysis (OR = 0.624 [0.023-16.709], p = 0.779). Moreover, the area under the receiver operating characteristic curve of the REB and LMR was 0.87 and 0.60. The most appropriate cutoff value for the REB was 2.21. The HCC patients with the REB ≤ 2.21 had a higher incidence of post-hepatectomy liver failure than those with the REB > 2.21 (60.0% versus 8.5%, p < 0.001). CONCLUSIONS: Gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase was valuable in predicting post-hepatectomy liver failure in HCC patients. KEY POINTS: • The relative enhancement ratio of the biliary system (REB) was an independent risk factor for post-hepatectomy liver failure in HCC patients. • HCC patients with the REB ≤ 2.21 had significantly higher incidence of post-hepatectomy liver failure than those with the REB > 2.21 (60.0% versus 8.5%).

Preoperative prediction of pathologic grade of HCC on gadobenate dimeglumine-enhanced dynamic MRI.

PURPOSE: To evaluate the value of gadobenate dimeglumine-enhanced MRI in predicting the pathologic grade of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Patients with pathologically proven HCC who underwent preoperative gadobenate dimeglumine-enhanced dynamic MRI were included. Two radiologists blinded to pathology results evaluated images in consensus. Lesions were evaluated quantitatively in terms of ratio of enhancement (RE), and qualitatively based on image features related to tumor aggressiveness. Logistic regression and ROC analyses were used to determine the value of these parameters to predict pathologic grade. RESULTS: In total, 221 patients (194 males, 27 females, aged 52.9 ± 11.7 years) with 49 poorly differentiated HCCs and 172 well/moderately differentiated HCCs were evaluated. Features significantly related to poorer pathologic grade at univariate analysis included lower RE in the early arterial phase (EAP) (p = 0.001), nonsmooth margins (p = 0.001), absence of capsule (p < 0.001), arterial peritumoral hyperenhancement (p < 0.001), higher AFP (p = 0.004), multiple tumors (p = 0.026), and larger tumor size (p = 0.028). At multivariate analysis, lower RE (EAP) (OR = 0.144, p = 0.002), absence of capsule (OR = 0.281, p = 0.004), and arterial peritumoral hyperenhancement (OR = 4.117, p < 0.001) were independent predictive factors for poorer pathologic grade. ROC analysis showed lower RE (EAP) was predictive of poorer pathologic grade (AUC = 0.667). AUC increased to 0.797 when combined with absence of capsule and presence of peritumoral hyperenhancement. CONCLUSIONS: Lower RE (EAP), absence of capsule, and arterial peritumoral hyperenhancement were predictive biomarkers for poorer pathologic grade of HCC on gadobenate dimeglumine-enhanced dynamic MRI. KEY POINTS: • Gadobenate dimeglumine-enhanced dynamic MRI was a useful quantitative biomarker for preoperative prediction of pathologic grade in patients with HCC. • Lower RE in the early arterial phase, absence of capsule, and arterial peritumoral hyperenhancement were potential imaging indicators for preoperative prediction of poorer pathologic grade of HCC on gadobenate dimeglumine-enhanced MRI. • A lower RE in the early arterial phase was effective at predicting poorer pathologic grade of HCCs but prediction is improved when combined with absence of capsule and presence of peritumoral hyperenhancement.

Gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase can predict progression in patients with liver cirrhosis.

OBJECTIVES: To determine the value of gadobenate dimeglumine (Gd-BOPTA)-enhanced biliary imaging from the hepatobiliary phase in predicting hepatic decompensation and insufficiency for patients with cirrhosis. METHODS: This single-center retrospective study included 270 patients who underwent Gd-BOPTA-enhanced magnetic resonance imaging. The relative enhancement ratios of the biliary system (REB) and liver parenchyma (REL) in patients with normal liver function without underlying chronic liver disease and three groups of patients with Child-Pugh A, Child-Pugh B, and Child-Pugh C disease were measured. After a mean follow-up of 38.5 ± 22.5 months, prognostic factors were evaluated using the Cox proportional hazards regression model. Receiver operating characteristic (ROC) curve analyses were performed to assess the capacity of the REB and REL to predict the development of hepatic decompensation and insufficiency. RESULTS: During the follow-up period, nine of 79 patients with Child-Pugh A disease developed hepatic decompensation. The REB was a significant predictive factor (hazard ratio (HR) = 0.40 (0.19-0.84); p = 0.016), but the REL showed no association with hepatic decompensation. Moreover, the areas under the ROC curves (AUCs) were 0.83 and 0.52 for the REB and REL, respectively. Thirty-eight of 207 patients with cirrhosis developed hepatic insufficiency. The REB was a significant predictive factor (HR = 0.24 (0.13-0.46); p < 0.0001), but the REL did not show statistically significant association with hepatic insufficiency. The AUCs were 0.82 and 0.57 for the REB and REL, respectively. CONCLUSIONS: Gd-BOPTA-enhanced biliary imaging from the hepatobiliary phase was valuable in predicting hepatic decompensation and insufficiency for cirrhotic patients. KEY POINTS: • Gd-BOPTA-enhanced biliary imaging was a significant predictive factor for hepatic decompensation in patients with cirrhosis. • Gd-BOPTA-enhanced biliary imaging was a significant predictive factor for hepatic insufficiency in patients with cirrhosis. • Gd-BOPTA-enhanced biliary imaging showed superior predictive values for adverse clinical outcomes compared to liver parenchymal imaging at the hepatobiliary phase.

The role of lesion hypointensity on gadobenate dimeglumine-enhanced hepatobiliary phase MRI as an additional major imaging feature for HCC classification using LI-RADS v2018 criteria.

OBJECTIVES: To determine the value of lesion hypointensity in the hepatobiliary phase (HBP) on gadobenate dimeglumine-enhanced MRI as an additional major imaging feature for diagnosis of hepatocellular carcinoma (HCC) using LI-RADS v2018 criteria. METHODS: Between March 2016 and August 2018, 235 patients with 250 hepatic nodules at high risk of HCC underwent gadobenate dimeglumine-enhanced MRI. Two radiologists independently evaluated the imaging features and classified the nodules based on LI-RADS v2018 criteria, and their consensus data were used to calculate the diagnostic performance of LI-RADS categories. Two modified LI-RADS definitions were as follows: (1) LI-RADS-m1: HBP hypointensity as an additional major feature; (2) LI-RADS-m2: HBP hypointensity as an alternative to "enhancing capsule" as an additional major feature. The diagnostic performance of LR-5 categories was compared using McNemar's test. RESULTS: The sensitivity and specificity for LR-5 classification using original LI-RADS v2018 criteria were 78.1% and 96.3%, respectively. Significantly improved sensitivity (82.7%; p = 0.004) with unchanged specificity (96.3%; p = 1.00) was seen for LR-5 classification using LI-RADS-m1. Similar sensitivity and specificity (82.7% and 96.3%, respectively) were also seen using LI-RADS-m2. Significantly improved sensitivity (79.5% vs. 64.0%; p = 0.031) with unchanged specificity (96.2% vs. 96.2%, p = 1.00) was seen using both LI-RADS-m1 and LI-RADS-m2 compared to the original LI-RADS v2018 for 39 HCC nodules measuring 10-19 mm. CONCLUSIONS: Lesion hypointensity on gadobenate dimeglumine-enhanced HBP MRI may improve sensitivity for LR-5 classification beyond that achievable using conventional LI-RADS v2018 criteria. Lesion hypointensity may prove a suitable alternative imaging feature to enhancing capsule for accurate LR-5 classification. KEY POINTS: • Including lesion hypointensity in the HBP as an additional major feature improved sensitivity for LR-5 classification on gadobenate dimeglumine-enhanced MRI. • Lesion hypointensity in the HBP can replace "enhancing capsule" as an additional major feature for LR-5 classification without impairing specificity.

Liver enhancement during hepatobiliary phase after Gd-BOPTA administration: correlation with liver and renal function.

OBJECTIVES: To assess the influence of liver and renal function on liver relative enhancement during hepatobiliary phase MRI after Gd-BOPTA administration. METHODS: In this IRB-approved retrospective cohort study, we included 326 patients who underwent Gd-BOPTA-enhanced 1.5T liver MRI, including hepatobiliary phase (HBP) acquired 90-150 min after injection, in two centres between Jan 2016 and Dec 2019. Liver signal intensity was measured on native and HBP phases and normalized to paraspinal muscles. Liver normalized relative enhancement (NRE) in HBP was calculated and compared with eGFR, total serum bilirubin and HBP acquisition delay by means of Spearman r correlation test and Mann-Whitney U test. RESULTS: 221/326 patients received 0.05 mmol/Kg Gd-BOPTA (group A), whereas 105/326 received 0.1 mmol/Kg (group B). Liver NRE in HBP was significantly higher in group B than in group A (0.55vs.0.33, p < 0.0001). In both groups, liver NRE in HBP had a negative correlation with total serum bilirubin level (r = - 0.32, p < 0.0001, group A; r = - 0.36, p = 0.0002, group B). Patients with total bilirubin > 1.2 mg/dl showed significantly lower NRE in HBP compared with those with total bilirubin ≤ 1.2 mg/dl (p < 0.0001, group A; p = 0.04, group B). Patients with impaired liver function in group B showed a NRE during HBP comparable with those with normal liver function in group A. No statistically significant correlation between liver NRE and eGFR or acquisition delay was observed. CONCLUSIONS: The degree of liver enhancement during HBP is not correlated with eGFR or acquisition delay, but it is significantly reduced in patients with impaired liver function. 0.1 mmol/kg Gd-BOPTA dose might be useful in patients with total serum bilirubin > 1.2 mg/dl. KEY POINTS: • The degree of liver enhancement during hepatobiliary phase after Gd-BOPTA administration has a negative correlation with total serum bilirubin level (r = - 0.32, p < 0.0001). • The degree of liver enhancement during HBP after Gd-BOPTA administration is not significantly correlated with renal function and acquisition delay (comprised between 90 and 150 min after contrast injection). • 0.1 mmol/Kg Gd-BOPTA dose might be preferable in patients with increased total serum bilirubin levels.

Hepatobiliary phase in cirrhotic patients with different Model for End-stage Liver Disease score: comparison of the performance of gadoxetic acid to gadobenate dimeglumine.

OBJECTIVES: The purpose of this study was to compare the performance of gadobenate dimeglumine-enhanced MRI and gadoxetic acid-enhanced MRI in the hepatobiliary phase (HBP) in cirrhotic patients with different degrees of liver dysfunction. METHODS: In this retrospective cross-sectional study, we analyzed the unenhanced phase and the HBP of 131 gadobenate dimeglumine-enhanced MRI examinations (gadobenate dimeglumine group) and 127 gadoxetic acid-enhanced MRI examinations (gadoxetic acid group) performed in 249 cirrhotic patients (181 men and 68 women; mean age, 64.8 years) from August 2011 to April 2017. For each MRI, the contrast enhancement index of the liver parenchyma was calculated and correlated to the Model For End-Stage Liver Disease (MELD) score (multiple linear regression analysis). A qualitative analysis of the adequacy of the HBP, adjusted for the MELD score (logistic regression analysis), was performed. RESULTS: The contrast enhancement index was inversely related (r = - 0.013) with MELD score in both gadoxetic acid and gadobenate dimeglumine group. At the same MELD score, the contrast enhancement index in the gadoxetic acid group was increased by a factor of 0.23 compared to the gadobenate dimeglumine group (p < 0.001), and the mean odds ratio to have an adequate HBP with gadoxetic acid compared to gadobenate dimeglumine was 3.64 (p < 0.001). The adequacy of the HBP in the gadoxetic acid group compared to the gadobenate dimeglumine group increased with the increase of the MELD score (exp(b)interaction = 1.233; p = 0.011). CONCLUSION: In cirrhotic patients, the hepatobiliary phase obtained with gadoxetic acid-enhanced MRI is of better quality in comparison to gadobenate dimeglumine-enhanced MRI, mainly in patients with high MELD score. KEY POINTS: • In cirrhotic patients, the adequacy of the hepatobiliary phase with gadoxetic acid-enhanced MRI is better compared to gadobenate dimeglumine-enhanced MRI. • Gadoxetic acid-enhanced MRI should be preferred to gadobenate dimeglumine-enhanced MRI in cirrhotic patients with MELD score > 10, if the hepatobiliary phase is clinically indicated. • In patients with high MELD score (> 15), the administration of the hepatobiliary agent could be useless; even though, if it is clinically indicated, we recommend to use gadoxetic acid given the higher probability of obtaining clinically relevant information.

[Pharmacokinetics of gadolinium-based contrast agents]. / Pharmakokinetik von gadoliniumhaltigen Kontrastmitteln.

BACKGROUND: Gadolinium-based contrast agents are used routinely in magnetic resonance imaging (MRI). They can be detected over a long period of time in some tissues (skin, brain, bone). OBJECTIVES: What is known on the pharmacokinetics of gadolinium-based contrast agents and on gadolinium deposition in various tissues? MATERIALS AND METHODS: Fundamental research and expert recommendations are discussed. RESULTS: Gadolinium-based contrast agents are distributed rapidly within the body and are eliminated by the kidneys. A fast initial elimination (half-life approximately 2 h) is followed by a slow elimination phase (half-life approximately 6 days), reflecting slow release from tissues. Deposition in the brain was observed mainly after administration of linear, non-ionic contrast agents. Whether gadolinium deposition in tissues consists of chelated or free gadolinium and whether otherwise healthy subjects are affected to a similar extent, is unclear. Currently, there are no proven risks associated with gadolinium deposition in the brain. CONCLUSIONS: Risks and benefits should be considered on an individual basis before MRI with gadolinium-based contrast agents (expected benefit, potentially undetected risks, available alternatives and their risks). Quantification of gadolinium in urine or blood from patients is not meaningful and should not be done outside clinical studies.

Whole-liver histogram analysis of hepatocyte-specific contrast-enhanced magnetic resonance imaging for predicting progression in patients with cirrhosis.

Background: Liver cirrhosis, as the terminal phase of chronic liver disease fibrosis, is associated with high morbidity and mortality. Traditional methods for assessing liver function, such as clinical scoring systems, offer only a global evaluation and may not accurately reflect regional liver function variations. This study aimed at evaluating the diagnostic potential of whole-liver histogram analysis of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) for predicting the progression of cirrhosis. Methods: In this retrospective study, 265 consecutive patients with cirrhosis admitted to the Department of Radiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University from August 2012 to September 2019 were enrolled. After the exclusion criteria were applied, 117 patients (84 males and 33 females) were divided into Child-Pugh A cirrhosis (n=43), Child-Pugh B cirrhosis (n=49), and Child-Pugh C cirrhosis (n=25). After correction for liver signal intensity with the spleen was completed, 19 histogram features of the whole liver were extracted and modeled to evaluate liver function, with the Child-Pugh class being incorporated as a clinical parameter. Receiver operating characteristic (ROC) curves were used to assess the diagnosis capability and determine the optimal cutoffs after a mean follow-up of 42.3±19.1 (range, 8-93) months. The association between significant histogram features and the cumulative incidence of hepatic insufficiency was analyzed with the adjusted Kaplan-Meier curve model. Results: Among 117 patients (12%), 14 developed hepatic insufficiency through a period of follow-up. Five features, including the median (P<0.01), 90th percentile (P<0.01), root mean squared (P<0.01), mean (P<0.01), and 10th percentile (P<0.05), were significantly different between the groups with and without hepatic insufficiency according to the Kruskal-Wallis test; in the ROC curve analysis, the area under the curve (AUC) of these features was 0.723 [95% confidence interval (CI): 0.653-0.793], 0.722 (95% CI: 0.652-0.792), 0.722 (95% CI: 0.652-0.792), 0.721 (95% CI: 0.651-0.791), and 0.674 (95% CI: 0.600-0.748) after correction, respectively (all P values <0.05). Median, 90th percentile, root mean squared, and mean were found to be significant factors in predicting liver insufficiency. The adjusted Kaplan-Meier curves revealed that patients with a feature level less than the cutoff, as compared to those with a level above the cutoff, showed a statistically shorter progression-free survival and higher incidences of hepatic insufficiency for significant features of median (cutoff =26.001; 21.28% versus 5.71%; P=0.02), 90th percentile (cutoff =86.263; 20.41% versus 5.88%; P<0.01), root mean squared (cutoff =1,028.477; 19.15% versus 7.14%; P=0.049), and mean (cutoff =27.484; 19.15% versus 7.14%; P=0.049). Patients with a 10th percentile less than -39.811 also showed a higher cumulative incidence of hepatic insufficiency than did those with a value higher than the cutoff (0.18% versus 7.46%; P=0.22). Conclusions: Whole-liver histogram analysis of Gd-BOPTA-enhanced MRI may serve as a noninvasive analytical method to predict hepatic insufficiency in patients with cirrhosis.

Quantitative parameters obtained from gadobenate dimeglumine-enhanced MRI at the hepatobiliary phase can predict post-hepatectomy liver failure and overall survival in patients with hepatocellular carcinoma.

PURPOSE: To determine the value of the quantitative parameters obtained from gadobenate dimeglumine-enhanced magnetic resonance imaging (MRI) at the hepatobiliary phase for predicting post-hepatectomy liver failure and overall survival in patients with hepatocellular carcinoma. METHOD: This multicenter retrospective study included 307 patients who underwent gadobenate dimeglumine-enhanced MRI. The quantitative liver-to-portal vein contrast ratio (LPC) and liver-spleen contrast ratio (LSC) at the hepatobiliary phase were measured. Logistic regression analyses were used to evaluate risk factors for post-hepatectomy liver failure. The capacity of the LPC and LSC to predict post-hepatectomy liver failure was evaluated via receiver operating characteristic (ROC) curve. The Cox proportional hazards regression was used to identify prognostic factors for overall survival (OS). RESULTS: Post-hepatectomy liver failure was observed in 69 patients (22.5%). The LPC and LSC were independent risk factors for the development of post-hepatectomy liver failure, and the areas under the ROC curves of LPC and LSC were 0.882 and 0.782, respectively. The predictive performance of LPC for post-hepatectomy liver failure was superior to LSC. The LPC and LSC were also significant prognostic factors for OS. The cut-off values for the LPC and LSC were 1.07 and 0.89, respectively. The 5-year OS rate was higher in patients with LPC > 1.07 or LSC > 0.89 than in patients with LPC ≤ 1.07 or LSC ≤ 0.89. CONCLUSIONS: The quantitative parameters obtained from gadobenate dimeglumine-enhanced MRI at the hepatobiliary phase were effective imaging biomarkers for predicting both post-hepatectomy liver failure and overall survival in patients with hepatocellular carcinoma.

Combined gadoxetic acid and gadobenate dimeglumine enhanced liver MRI: a parameter optimization study.

PURPOSE: To demonstrate the feasibility of combined delayed-phase gadoxetic acid (GA) and gadobenate dimeglumine (GD) enhanced liver MRI for improved detection of liver metastases, and to optimize contrast agent dose, timing, and flip angle (FA). METHODS: Fourteen healthy volunteers underwent liver MRI at 3.0T at two visits during which they received two consecutive injections: 1. GA (Visit 1 = 0.025 mmol/kg; Visit 2 = 0.05 mmol/kg) and 2. GD (both visits = 0.1 mmol/kg) 20 min after GA administration. Two sub-studies were performed: Experiment-1 Eight subjects underwent multi-phase breath-held 3D-fat-saturated T1-weighted spoiled gradient echo (SGRE) imaging to determine the optimal imaging window for the combined GA + GD protocol to create a homogeneously hyperintense liver and vasculature ("plain-white-liver") with maximum contrast to muscle which served as a surrogate for metastatic lesions in both experiments. Experiment-2 Six subjects underwent breath-held 3D-fat-saturated T1-weighted SGRE imaging at three different FA to determine the optimal FA for best image contrast. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated. RESULTS: Experiment-1 The combined GA + GD protocol created a homogeneously hyperintense liver and vasculature with maximum CNR liver/muscle at approximately 60-120 s after automatic GD-bolus detection. Experiment-2 Flip angles between 25° and 35° at a dose of 0.025 mmol/kg GA provided the best combination that minimized liver/vasculature CNR, while maximizing liver/muscle CNR. CNR performance to achieve a "plain-white-liver" was superior with 0.025 mmol/kg GA compared to 0.05 mmol/kg. CONCLUSION: Combined GA + GD enhanced T1-weighted MRI is feasible to achieve a homogeneously "plain-white-liver". Future studies need to confirm that this protocol can improve sensitivity of liver lesion detection in patients with metastatic liver disease.

A machine learning approach for differentiating malignant from benign enhancing foci on breast MRI.

BACKGROUND: Differentiate malignant from benign enhancing foci on breast magnetic resonance imaging (MRI) through radiomic signature. METHODS: Forty-five enhancing foci in 45 patients were included in this retrospective study, with needle biopsy or imaging follow-up serving as a reference standard. There were 12 malignant and 33 benign lesions. Eight benign lesions confirmed by over 5-year negative follow-up and 15 malignant histopathologically confirmed lesions were added to the dataset to provide reference cases to the machine learning analysis. All MRI examinations were performed with a 1.5-T scanner. One three-dimensional T1-weighted unenhanced sequence was acquired, followed by four dynamic sequences after intravenous injection of 0.1 mmol/kg of gadobenate dimeglumine. Enhancing foci were segmented by an expert breast radiologist, over 200 radiomic features were extracted, and an evolutionary machine learning method ("training with input selection and testing") was applied. For each classifier, sensitivity, specificity and accuracy were calculated as point estimates and 95% confidence intervals (CIs). RESULTS: A k-nearest neighbour classifier based on 35 selected features was identified as the best performing machine learning approach. Considering both the 45 enhancing foci and the 23 additional cases, this classifier showed a sensitivity of 27/27 (100%, 95% CI 87-100%), a specificity of 37/41 (90%, 95% CI 77-97%), and an accuracy of 64/68 (94%, 95% CI 86-98%). CONCLUSION: This preliminary study showed the feasibility of a radiomic approach for the characterisation of enhancing foci on breast MRI.