The clinical value of hepatic extracellular volume fraction using routine multiphasic contrast-enhanced liver CT for staging liver fibrosis

Liver function estimation using multiphase hepatic CT: diagnostic performance of iodine-uptake and volumetric parameters

OBJECTIVES

To investigate whether multiphase hepatic CT can predict liver function measured with indocyanine-green-retention test (ICG-R15) and identify patients with severe liver dysfunction contraindicating major hepatectomy, defined as ICG-R15 ≥ 20%, compared to technetium-99m-galactosyl serum albumin (99mTc-GSA) scintigraphy.

MATERIALS AND METHODS

This retrospective study included 118 patients (84 men, mean age, 69.4 ± 11.3 years) who underwent ICG-R15, 99mTc-GSA, and multi-phase CT including early portal-venous-phase and 3-min delayed-phase. CT-derived extracellular volume fraction (ECV), iodine washout rate (IWR), liver and spleen volumes normalized by body-surface-area (LV/BSA and SpV/BSA, respectively), and 99mTc-GSA-derived blood clearance index (HH15) and liver receptor index (LHL15) were quantified. Each parameter was compared between ICG-R15 ≥ 20% (n = 22) and ICG-R15 < 20% (n = 96) groups. Correlations with ICG-R15 were analyzed. The diagnostic performance to predict ICG-R15 ≥ 20% was assessed with areas under the receiver operating characteristic curve (AUC). Multivariable logistic regression analysis was used to identify independent CT predictors, and combined performance was determined.

RESULTS

In the ICG-R15 ≥ 20% group, IWR (p < 0.001), LV/BSA (p = 0.026), LHL15 (p < 0.001) were lower and ECV (p = 0.001), SpV/BSA (p = 0.005), and HH15 (p < 0.001) were higher compared to ICG-R15 < 20% group. ICG-R15 showed positive correlations with ECV (r = 0.355), SpV/BSA (r = 0.248), and HH15 (r = 0.385), while negative correlations with IWR (r = -0.523), LV/BSA (r = -0.123, not statistically significant), and LHL15 (r = -0.504). The AUC of ECV, IWR, LV/BSA, SpV/BSA, HH15, and LHL15 were 0.719, 0.845, 0.653, 0.694, 0.844, and 0.878, respectively. IWR, SpV/BSA, and LV/BSA were independent predictors, with a combined AUC of 0.924.

CONCLUSION

IWR predicted liver function better than ECV and hepatosplenic volumetry. The combined IWR and volumetry yielded an accurate prediction of severe liver dysfunction.

KEY POINTS

Question Despite the widespread use of multiphase CT in patients with hepatobiliary diseases, its potential role in assessing liver function has been scarcely evaluated. Findings Iodine washout rate (IWR), liver volume indexed by body surface area, and spleen volume indexed by body surface area were independent predictors for severe liver dysfunction. Clinical relevance Combined IWR and hepatosplenic volumetry on routine hepatic CT may help assess hepatic function for optimizing treatment strategies and predicting patient prognosis.

Reliability assessment of CT enhancement rate and extracellular volume in liver fibrosis prediction

BACKGROUND

Reliable, non-invasive evaluation of liver fibrosis is essential for early disease management. Computed tomography (CT)-based extracellular volume (ECV) fraction and portal venous phase enhancement rate (VP-ER) have shown potential in quantifying mild-to-moderate fibrosis. This study investigates the diagnostic performance of ECV and VP-ER in differentiating non-significant (F0-F1) from significant (F2-F3) fibrosis in biopsy-confirmed patients.

METHODS

Ninety-three patients (20-72 years, 56.9% male) undergoing liver biopsy and multiphasic CT scans were retrospectively enrolled. Patients with METAVIR F4 cirrhosis or incomplete imaging/pathological data were excluded. Hematocrit levels were obtained on the day of CT. ECV was calculated from differences in liver and aortic attenuation between delayed and enhanced phases, adjusted for hematocrit. VP-ER was derived as the ratio of liver attenuation in venous to portal venous phases multiplied by 100. Spearman's correlation, receiver operating characteristic (ROC) curves, and DeLong tests evaluated their performance. Multiple logistic regression assessed independent contributions of ECV and VP-ER to fibrosis status.

RESULTS

Fifty-three patients had no significant fibrosis (F0-F1) and 40 had significant fibrosis (F2-F3). ECV demonstrated a moderate correlation with fibrosis grade (r = 0.531, p < 0.0001), while VP-ER showed a weaker yet statistically significant correlation (r = 0.363, p = 0.0003). ROC analyses yielded an area under the curve (AUC) of 0.698 for ECV (cut-off = 38%) and 0.763 for VP-ER (cut-off = 71%), with no significant difference between AUCs (p = 0.358). VP-ER accurately classified 70 patients, while ECV correctly predicted 65. Logistic regression revealed significant associations for both VP-ER (OR = 1.08; p = 0.007) and ECV (OR = 1.025; p = 0.0132), achieving 72.04% classification accuracy and an overall AUC of 0.756 (95% CI: 0.688-0.863).

CONCLUSION

ECV fraction and VP-ER demonstrated reliable, complementary capabilities for distinguishing non-significant fibrosis from significant fibrosis. Their combined use in routine multiphasic CT protocols may reduce dependence on invasive biopsy while offering robust sensitivity and specificity for early fibrosis assessment. Further studies including cirrhotic populations and larger cohorts are recommended.

Computed Tomography-Derived Extracellular Volume Fraction and Splenic Size for Liver Fibrosis Staging

OBJECTIVE

Extracellular volume fraction (fECV) and liver and spleen size have been correlated with liver fibrosis stages and cirrhosis. The purpose of the current study was to determine the predictive value of fECV alone and in conjunction with measurement of liver and spleen size for severity of liver fibrosis.

METHODS

This was a retrospective study of 95 subjects (65 with liver biopsy and 30 controls). Spearman rank correlation coefficient was used to assess correlation between radiological markers and fibrosis stage. Receiver operating characteristic analysis was performed to assess the discriminative ability of radiological markers for significant (F2+) and advanced (F3+) fibrosis and cirrhosis (F4), by reporting the area under the curve (AUC).

RESULTS

The cohort had a mean age of 51.4 ± 14.4 years, and 52 were female (55%). There were 36, 5, 6, 9, and 39 in fibrosis stages F0, F1, F2, F3, and F4, respectively. Spleen volume alone showed the highest correlation ( r = 0.552, P < 0.001) and AUCs of 0.823, 0.807, and 0.785 for identification of significant and advanced fibrosis and cirrhosis, respectively. Adding fECV to spleen length improved AUCs (0.764, 0.745, and 0.717 to 0.812, 0.781, and 0.738, respectively) compared with splenic length alone. However, adding fECV to spleen volume did not improve the AUCs for significant or advanced fibrosis or cirrhosis.

CONCLUSIONS

Spleen size (measured in length or volume) showed better correlation with liver fibrosis stages compared with fECV. The combination of fECV and spleen length had higher accuracy compared with fECV alone or spleen length alone.

Interpretable machine learning based on CT-derived extracellular volume fraction to predict pathological grading of hepatocellular carcinoma

PURPOSE

To develop a non-invasive auxiliary assessment method based on CT-derived extracellular volume (ECV) to predict the pathological grading (PG) of hepatocellular carcinoma (HCC).

METHODS

The study retrospectively analyzed 238 patients who underwent HCC resection surgery between January 2013 and April 2023. Six machine learning algorithms were employed to construct predictive models for HCC PG: logistic regression, extreme gradient boosting, Light Gradient Boosting Machine (LightGBM), random forest, adaptive boosting, and Gaussian naive Bayes. Model performance was evaluated using receiver operating characteristic curve analysis, including area under the curve (AUC), sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and F1 score. Calibration plots were used for visual evaluation of model calibration. Clinical decision curve analysis was performed to assess potential clinical utility by calculating net benefit.

RESULTS

166 patients from Hospital A were allocated to the training set, while 72 patients from Hospital B (constituting 30.25% of the total sample) were assigned to the test set. The model achieved an AUC of 1.000 (95%CI: 1.000-1.000) in the training set and 0.927 (95%CI: 0.837-0.999) in the validation set, respectively. Ultimately, the model achieved an AUC of 0.909 (95%CI: 0.837-0.980) in the test set, with an accuracy of 0.778, sensitivity of 0.906, specificity of 0.789, negative predictive value of 0.556, and F1 score of 0.908.

CONCLUSION

This study successfully developed and validated a non-invasive auxiliary assessment method based on CT-derived ECV to predict the HCC PG, providing important supplementary information for clinical decision-making.

Advancements of non‐invasive imaging technologies for the diagnosis and staging of liver fibrosis: Present and future

Liver fibrosis is a reparative response triggered by liver injury. Non‐invasive assessment and staging of liver fibrosis in patients with chronic liver disease are of paramount importance, as treatment strategies and prognoses depend significantly on the degree of fibrosis. Although liver fibrosis has traditionally been staged through invasive liver biopsy, this method is prone to sampling errors, particularly when biopsy sizes are inadequate. Consequently, there is an urgent clinical need for an alternative to biopsy, one that ensures precise, sensitive, and non‐invasive diagnosis and staging of liver fibrosis. Non‐invasive imaging assessments have assumed a pivotal role in clinical practice, enjoying growing popularity and acceptance due to their potential for diagnosing, staging, and monitoring liver fibrosis. In this comprehensive review, we first delved into the current landscape of non‐invasive imaging technologies, assessing their accuracy and the transformative impact they have had on the diagnosis and management of liver fibrosis in both clinical practice and animal models. Additionally, we provided an in‐depth exploration of recent advancements in ultrasound imaging, computed tomography imaging, magnetic resonance imaging, nuclear medicine imaging, radiomics, and artificial intelligence within the field of liver fibrosis research. We summarized the key concepts, advantages, limitations, and diagnostic performance of each technique. Finally, we discussed the challenges associated with clinical implementation and offer our perspective on advancing the field, hoping to provide alternative directions for the future research.

Discriminating atypical parotid carcinoma and pleomorphic adenoma utilizing extracellular volume fraction and arterial enhancement fraction derived from contrast-enhanced CT imaging: A multicenter study

OBJECTIVES

To investigate the added value of extracellular volume fraction (ECV) and arterial enhancement fraction (AEF) derived from enhanced CT to conventional image and clinical features for differentiating between pleomorphic adenoma (PA) and atypical parotid adenocarcinoma (PCA) pre-operation.

METHODS

From January 2010 to October 2023, a total of 187 cases of parotid tumors were recruited, and divided into training cohort (102 PAs and 51 PCAs) and testing cohort (24 PAs and 10 atypical PCAs). Clinical and CT image features of tumor were assessed. Both enhanced CT-derived ECV and AEF were calculated. Univariate analysis identified variables with statistically significant differences between the two subgroups in the training cohort. Multivariate logistic regression analysis with the forward variable selection method was used to build four models (clinical model, clinical model+ECV, clinical model+AEF, and combined model). Diagnostic performances were evaluated using receiver operating characteristic (ROC) curve analyses. Delong's test compared model differences, and calibration curve and decision curve analysis (DCA) assessed calibration and clinical application.

RESULTS

Age and boundary were chosen to build clinical model, and to construct its ROC curve. Amalgamating the clinical model, ECV, and AEF to establish a combined model demonstrated superior diagnostic effectiveness compared to the clinical model in both the training and test cohorts (AUC = 0.888, 0.867). There was a significant statistical difference between the combined model and the clinical model in the training cohort (p = 0.0145).

CONCLUSIONS

ECV and AEF are helpful in differentiating PA and atypical PCA, and integrating clinical and CT image features can further improve the diagnostic performance.

Noninvasive diagnosis of liver cirrhosis: qualitative and quantitative imaging biomarkers

A diagnosis of cirrhosis initiates a shift in the management of chronic liver disease and affects the diagnostic workflow and treatment decision of primary liver cancer. Liver biopsy remains the gold standard for cirrhosis diagnosis, but it is invasive and susceptible to sampling bias and observer variability. Various qualitative and quantitative imaging biomarkers based on ultrasound, CT and MRI have been proposed for noninvasive diagnosis of cirrhosis. Qualitative imaging features are easy to apply but have moderate diagnostic sensitivity. Elastography techniques allow quantitative assessment of liver stiffness and are highly accurate for cirrhosis diagnosis. Ultrasound elastography are widely used in clinical practice, while MR elastography has narrower availability. Although not applicable in clinical practice yet, other quantitative imaging features, including liver surface nodularity, linear and volumetric measurement, extracellular volume fraction, liver enhancement on hepatobiliary phase, and parameters derived from diffusion-weighted imaging, can provide additional information of liver morphology, perfusion, and function, thus may increase diagnosis performance. The introduction of radiomics and deep learning has further improved diagnostic accuracy while reducing subjectivity. Several imaging features may also help to assess liver function and outcomes in patients with cirrhosis. In this review, we summarize the qualitative and quantitative imaging biomarkers for noninvasive cirrhosis diagnosis, and the assessment of liver function and outcomes, and discuss the challenges and future directions in this field.

Survival prediction of hepatocellular carcinoma by measuring the extracellular volume fraction with single-phase contrast-enhanced dual-energy CT imaging

Purpose

This study aimed to investigate the value of quantified extracellular volume fraction (fECV) derived from dual-energy CT (DECT) for predicting the survival outcomes of patients with hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE).

Materials and methods

A total of 63 patients with HCC who underwent DECT before treatment were retrospectively included. Virtual monochromatic images (VMI) (70 keV) and iodine density images (IDI) during the equilibrium phase (EP) were generated. The tumor VMI-fECV and IDI-fECV were measured and calculated on the whole tumor (Whole) and maximum enhancement of the tumor (Maximum), respectively. Univariate and multivariate Cox models were used to evaluate the effects of clinical and imaging predictors on overall survival (OS) and progression-free survival (PFS).

Results

The correlation between tumor VMI-fECV and IDI-fECV was strong (both p< 0.001). The Bland-Altman plot between VMI-fECV and IDI-fECV showed a bias of 5.16% for the Whole and 6.89% for the Maximum modalities, respectively. Increasing tumor VMI-fECV and IDI-fECV were positively related to the effects on OS and PFS (both p< 0.05). The tumor IDI-fECV-Maximum was the only congruent independent predictor in patients with HCC after TACE in the multivariate analysis on OS (p = 0.000) and PFS (p = 0.028). Patients with higher IDI-fECV-Maximum values had better survival rates above the optimal cutoff values, which were 35.42% for OS and 29.37% for PFS.

Conclusion

The quantified fECV determined by the equilibrium-phase contrast-enhanced DECT can potentially predict the survival outcomes of patients with HCC following TACE treatment.

Extracellular volume fraction using contrast-enhanced CT is useful in differentiating intrahepatic cholangiocellular carcinoma from hepatocellular carcinoma

Objectives

To evaluate whether tumor extracellular volume fraction (fECV) on contrast-enhanced computed tomography (CT) aids in the differentiation between intrahepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC).

Methods

In this retrospective study, 113 patients with pathologically confirmed ICC (n = 39) or HCC (n = 74) who had undergone preoperative contrast-enhanced CT were enrolled. Enhancement values of the tumor (Etumor) and aorta (Eaorta) were obtained in the precontrast and equilibrium phase CT images. fECV was calculated using the following equation: fECV [%] = Etumor/Eaorta × (100 - hematocrit [%]). fECV values were compared between the ICC and HCC groups using Welch's t-test. The diagnostic performance of fECV for differentiating ICC and HCC was assessed using receiver-operating characteristic (ROC) analysis. fECV and the CT imaging features of tumors were evaluated by two radiologists. Multivariate logistic regression analysis was performed to identify factors predicting a diagnosis of ICC.

Results

Mean fECV was significantly higher in ICCs (43.8% ± 13.2%) than that in HCCs (31.6% ± 9.0%, p < 0.001). The area under the curve for differentiating ICC from HCC was 0.763 when the cutoff value of fECV was 41.5%. The multivariate analysis identified fECV (unit OR: 1.10; 95% CI: 1.01-1.21; p < 0.05), peripheral rim enhancement during the arterial phase (OR: 17.0; 95% CI: 1.29-225; p < 0.05), and absence of washout pattern (OR: 235; 95% CI: 14.03-3933; p < 0.001) as independent CT features for differentiating between the two tumor types.

Conclusions

A high value of fECV, peripheral rim enhancement during the arterial phase, and absence of washout pattern were independent factors in the differentiation of ICC from HCC.

Conventional and artificial intelligence-based computed tomography and magnetic resonance imaging quantitative techniques for non-invasive liver fibrosis staging

Chronic liver disease (CLD) ultimately develops into liver fibrosis and cirrhosis and is a major public health problem globally. The assessment of liver fibrosis is important for patients with CLD for prognostication, treatment decisions, and surveillance. Liver biopsies are traditionally performed to determine the stage of liver fibrosis. However, the risks of complications and technical limitations restrict their application to screening and sequential monitoring in clinical practice. CT and MRI are essential for evaluating cirrhosis-associated complications in patients with CLD, and several non-invasive methods based on them have been proposed. Artificial intelligence (AI) techniques have also been applied to stage liver fibrosis. This review aimed to explore the values of conventional and AI-based CT and MRI quantitative techniques for non-invasive liver fibrosis staging and summarized their diagnostic performance, advantages, and limitations.

Predictive value of CT-based extracellular volume fraction in the preoperative pathologic grading of rectal adenocarcinoma: A preliminary study

OBJECTIVE

This study aimed to investigate whether the extracellular volume fraction (ECV) determined using enhanced computed tomography (CT) can predict the pathologic grade of rectal adenocarcinoma.

METHODS

We prospectively analyzed 43 patients with rectal adenocarcinoma confirmed surgically and pathologically and who had undergone preoperative enhanced CT imaging. The plain, arterial, venous, and balance phase values were recorded, and the absolute contrast-enhanced CT differences ΔS1 = HU_{arterial phase}-HU_{plain scan}, ΔS2 = HU_{venous phase}-HU_{plain scan}, ΔS3 = HU_{balance phase}-HU_{plain scan} were obtained. The ECV of the primary lesion was calculated by measuring the CT values of the regions of interest in the plain and balance phases. Patients were allocated to either a low-grade or a high-grade group based on the histologic grading standard for colorectal adenocarcinoma (nonspecial type, World Health Organization 2010 standard). The differences in the parameters between the two groups were evaluated for statistical significance. A receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficiency.

RESULTS

The 43 enrolled patients [12 in the high-grade group (27.9%) and 31 in the low-grade group (72.1%)] had an average age of 64.47 years. The arterial phase (P = 0.005) as well as ΔS1 (P = 0.006), ΔS3 (P = 0.021), and ECV (P＜ 0.001) differed significantly between the high-grade and low-grade groups, with ECV (P＜ 0.001) and ΔS3 (P = 0.042) being positively correlated with the pathologic grade and arterial phase (P = 0.025) and ΔS1 (P = 0.005) being negatively correlated. The ROC curve demonstrated that the best efficacy in evaluating the pathologic grade of rectal cancer was achieved by ECV, with an area under the curve of 0.892 (95% confidence interval: 0.757-1.000). The diagnostic threshold was 34.42%, sensitivity was 91.7%, and specificity was 83.9%.

CONCLUSION

The use of enhanced CT to obtain ECV is helpful in predicting the pathologic grade of rectal cancer; however, this result has to be confirmed in a study with a larger sample size.

Dual-energy CT quantification of extracellular liver volume predicts short-term disease progression in patients with hepatitis B liver cirrhosis-acute decompensation

BACKGROUND

Liver cirrhosis-acute decompensation (LC-AD) has rapid short-term disease progression and difficult early risk stratification. The purpose is to develop and validate a model based on dual-energy CT quantification of extracellular liver volume (ECV_IC-liver) for predicting the occurrence of acute-on-chronic liver failure (ACLF) within 90 days in patients with hepatitis B (HBV) LC-AD.

METHODS

The retrospective study included patients with HBV LC-AD who underwent dual-energy CT scans of the liver from January 2018 to March 2022 and were randomized to training group (215 patients) and validation group (92 patients). The primary outcome was the need for readmission within 90 days due to ACLF. Based on the training group data, independent risk factors for disease progression in clinical and dual-energy CT parameters were identified and modeled by logistic regression analysis. Based on the training and validation groups data, receiver operating characteristic (ROC) curves, calibration curves, and decision analysis curves (DCA) were used to verify the discrimination, calibration, and clinical validity of the nomogram.

RESULTS

Chronic liver failure consortium-acute decompensation score (CLIF-C ADs) (p = 0.008) and ECV_IC-liver (p < 0.001) were independent risk factors for ACLF within 90 days. The AUC of the model combined ECV_IC-liver and CLIF-C ADs were 0.893 and 0.838 in the training and validation groups, respectively. The calibration curves show good agreement between predicted and actual risks. The DCA indicates that the model has good clinical application.

CONCLUSION

The model combined ECV_IC-liver and CLIF-C ADs can early predict the occurrence of ACLF within 90 days in HBV LC-AD patients.

Extracellular volume fraction obtained by dual-energy CT depicting the etiological differences of liver fibrosis

PURPOSE

To assess etiological differences in extracellular volume fraction (ECV) and evaluate its influence on staging performance.

METHODS

A total of 166 patients with normal liver (n = 14) and chronic liver disease related to viral hepatitis (n = 71), alcohol (n = 44), and nonalcoholic steatohepatitis (NASH) (n = 37) underwent dual-energy CT (DECT) of the liver (5-min equilibrium-phase images) between January 2020 and July 2022. The iodine densities of the parenchyma and aorta were measured and ECV was calculated. Comparisons of ECV between each etiology and METAVIR fibrosis stage were statistically analyzed (p < 0.05).

RESULTS

ECV in each etiology and all patients significantly increased with higher fibrosis stage (p < 0.001) and showed a strong or moderate correlation with fibrosis stage (Spearman's ρ; all patients, 0.701; viral hepatitis, 0.638; alcoholic, 0.885; NASH, 0.791). In stages F2-F4, ECV in alcoholic liver disease was significantly larger than those for viral hepatitis and NASH (p < 0.05); however, no significant difference in stage F1 was found among the three etiologies. The cutoff values and areas under the receiver operating characteristic curve (AUC-ROCs) for discriminating fibrosis stage (≥ F1- ≥ F4) were higher for alcohol (cutoff values and AUC-ROC; 20.1% and 0.708 for ≥ F1, 23.8% and 0.990 for ≥ F2, 24.3% and 0.968 for ≥ F3, and 26.6% and 0.961 for ≥ F4, respectively) compared with those for the others.

CONCLUSION

ECV in alcoholic liver disease is higher than that in other etiologies in the advanced stages of fibrosis, and etiological differences in ECV affect the staging performance of fibrosis.

Noninvasive Liver Fibrosis Staging: Comparison of MR Elastography with Extracellular Volume Fraction Analysis Using Contrast-Enhanced CT

Purpose: To compare the accuracy of liver fibrosis staging with MR elastography and of staging with extracellular volume fraction (fECV) analysis using contrast-enhanced CT. Methods: This retrospective study included 60 patients who underwent both MR elastography and contrast-enhanced CT before liver surgery between October 2013 and July 2020. Two radiologists independently measured liver stiffness of MR elastography and fECV of CT images. Accuracy for liver fibrosis staging was assessed using receiver operating characteristic (ROC) analysis. Correlations between liver stiffness or fECV and liver fibrosis were also evaluated by means of the Spearman rank correlation coefficient. Results: The areas under the ROC curves for MR elastography for each stage differentiation of ≥F1 (0.85, 0.82 for the two radiologists), ≥F2 (0.88, 0.89), ≥F3 (0.87, 0.86), and F4 (0.84, 0.83) were greater than those for fECV analysis with CT (0.64, p = 0.06, 0.69, p = 0.2; 0.62, p < 0.005, 0.63, p < 0.005; 0.62, p < 0.005, 0.62, p < 0.01; and 0.70, p = 0.08, 0.71, p = 0.2, respectively). The correlation coefficients between liver stiffness and liver fibrosis in A0 (0.67, 0.69 for the two radiologists), A1 (0.64, 0.66) and A2 group (0.58, 0.51) were significantly higher than those between fECV and liver fibrosis (0.28, 0.30; 0.27, 0.31; and 0.23, 0.07; p < 0.05 for all comparisons). Conclusion: MR elastography allows for more accurate liver fibrosis staging compared with fECV analysis with CT. In addition, MR elastography may be less affected than fECV analysis by the inflammatory condition.

Nomogram based on CT-derived extracellular volume for the prediction of post-hepatectomy liver failure in patients with resectable hepatocellular carcinoma

OBJECTIVES

This study aimed to develop and validate a nomogram based on extracellular volume (ECV) derived from computed tomography (CT) for predicting post-hepatectomy liver failure (PHLF) in patients with resectable hepatocellular carcinoma (HCC).

METHODS

A total of 202 patients with resectable HCC from two hospitals were enrolled and underwent multiphasic contrast-enhanced CT before surgery. One hundred twenty-one patients from our hospital and 81 patients from another hospital were assigned to the training cohort and the validation cohort, respectively. CT-derived ECV was measured using nonenhanced and equilibrium-phase-enhanced CT images. The nomogram was developed with independent predictors of PHLF. Predictive performance and calibration were assessed by receiver operator characteristic (ROC) analysis and Hosmer-Lemeshow test, respectively. The Delong test was used to compare the areas under the curve (AUCs).

RESULTS

CT-derived ECV had a strong correlation with the postoperative pathological fibrosis stage of the background liver (p < 0.001, r = 0.591). The nomogram combining CT-derived ECV, serum albumin (Alb), and serum total bilirubin (Tbil) obtained higher AUCs than the albumin-bilirubin (ALBI) score for predicting PHLF in both the training cohort (0.828 vs. 0.708; p = 0.004) and the validation cohort (0.821 vs. 0.630; p < 0.001). The nomogram showed satisfactory goodness of fit for PHLF prediction in the training and validation cohorts (p = 0.621 and 0.697, respectively).

CONCLUSIONS

The nomogram contributes to the preoperative prediction of PHLF in patients with resectable HCC.

KEY POINTS

• CT-derived ECV had a strong correlation with the postoperative pathological fibrosis stage of the background liver. • CT-derived ECV was an independent predictor of PHLF in patients with resectable HCC. • The nomogram based on CT-derived ECV showed a superior prediction efficacy than that of clinical models (including Child-Pugh stage, MELD score, and ALBI score).

Assessment of liver cirrhosis severity with extracellular volume fraction MRI

We aimed to investigate the diagnostic utility of MRI extracellular volume fraction (ECV) for the assessment of liver cirrhosis severity as defined by Child–Pugh class. In this retrospective study, 90 patients (68 cirrhotic patients and 22 controls), who underwent multiparametric liver MRI, were identified. Hepatic T1 relaxation times and ECV were assessed. Clinical scores of liver disease severity were calculated. One-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison test, Spearman’s correlation coefficient, and receiver operating characteristic (ROC) analysis were used for statistical analysis. In cirrhotic patients, hepatic native T1 increased depending on Child–Pugh class (620.5 ± 78.9 ms (Child A) vs. 666.6 ± 73.4 ms (Child B) vs. 828.4 ± 91.2 ms (Child C), P < 0.001). ECV was higher in cirrhotic patients compared to the controls (40.1 ± 11.9% vs. 25.9 ± 4.5%, P < 0.001) and increased depending of Child–Pugh class (33.3 ± 6.0% (Child A) vs. 39.6 ± 4.9% (Child B) vs. 52.8 ± 1.2% (Child C), P < 0.001). ECV correlated with Child–Pugh score (r = 0.64, P < 0.001). ECV allowed differentiating between Child–Pugh classes A and B, and B and C with an AUC of 0.785 and 0.944 (P < 0.001, respectively). The diagnostic performance of ECV for differentiating between Child–Pugh classes A and B, and B and C was higher compared to hepatic native T1 (AUC: 0.651 and 0.910) and MELD score (AUC: 0.740 and 0.795) (P < 0.05, respectively). MRI-derived ECV correlated with Child–Pugh score and had a high diagnostic performance for the discrimination of different Child–Pugh classes. ECV might become a valuable non-invasive biomarker for the assessment of liver cirrhosis severity.

Comparison of Liver Fibrosis and Function Indices with Extracellular Volume using Dual-Energy CT: A Retrospective Study

BACKGROUND

Dual-energy computed tomography (DECT) enables the direct measurement of iodine accumulation in the extracellular space.

OBJECTIVE

To compare measures of liver fibrosis and function with extracellular volume (ECV) from iodine/water images using DECT.

METHODS

Data was obtained from 119 consecutive patients who underwent abdominal DECT. A region of interest was set in the right lobe of the liver, pancreas, spleen, and aorta on iodine density images. ECV was calculated using the following formula: ECV = (1  hematocrit) × [iodine concentration in the liver (or pancreas, spleen) / iodine concentration in the aorta]. The severity of liver fibrosis was estimated using the aminotransferase/platelet ratio index (APRI) and the Fibrosis-4 (FIB-4) index. Liver function was assessed by the Child-Pugh classification and albumin-bilirubin (ALBI) grade. Data were analyzed by Spearman rank correlation coefficient, one-way analysis of variance, and post hoc analysis.

RESULTS

The correlation between ECV and fibrosis indices (APRI and FIB-4) was only significant and with a weak magnitude for the liver ECV quantification at the equilibrium phase (r=0.25 and r=0.20, respectively). The correlations between liver function index and ECV quantification were more robust than with fibrosis index. The highest correlations (r=0.50) were found between ALBI grade and liver ECV at the equilibrium phase. Liver ECV value at the equilibrium phase were significant difference between ALBI grade 1 vs. 2 and grade 1 vs. 3.

CONCLUSION

Liver ECV quantification by DECT is more suitable for evaluating liver function than liver fibrosis severity.

Dual-Energy Computed Tomography in Diffuse Liver Diseases

Dual-energy computed tomography (DECT) is an advancement in the field of CT, where images are acquired at two energies. Materials are identified and quantified based on their attenuation pattern at two different energy beams using various material decomposition algorithms. With its ability to identify and quantify materials such as fat, calcium, iron, and iodine, DECT adds great value to conventional CT and has innumerable applications in body imaging. Continuous technological advances in CT scanner hardware, material decomposition algorithms, and image reconstruction software have led to considerable growth of these applications. Among all organs, the liver is the most widely investigated by DECT, and DECT has shown promising results in most liver applications. In this article, we aim to provide an overview of the role of DECT in the assessment of diffuse liver diseases, mainly the deposition of fat, fibrosis, and iron and review the most relevant literature.

Quantification of liver extracellular volume using dual-energy CT for ruling out high-risk varices in cirrhosis

PURPOSE

To determine the performance of quantification of liver extracellular volume fraction (fECV) using dual-energy CT (DECT) compared with CT imaging for ruling out high-riskesophageal varices(HRV) in cirrhotic patients.

METHODS

We retrospectively analyzed 229 cirrhotic patients (training [n = 159] and internal validation cohorts [n = 70]) who underwent dual-source DECT, serum marker assessment, and esophagogastroduodenoscopy (EGD) from 2017 to 2020. The fECV score was measured using iodine maps from 3-minute delayed, equilibrium-phase images at 100/140 Sn kVp. The association of CT parameters and serum markers with HRV was investigated. Criteria combining the fECV score (≤ 25.1%) or CT imaging with platelet count (> 150,000/mm³) were created and compared to rule out HRV.

RESULTS

In the training cohort, the fECV score (odds ratio (OR), 1.20; 95% confidence interval (CI), 1.09, 1.32) and CT imaging (OR, 28.21; 95% CI, 9.31, 85.93) were independent predictors of HRV, along with platelet count (OR, 0.85 and 0.78). Criteria combining the fECV score with platelet count showed significantly better performance than those combining CT imaging with platelet count in ruling out HRV (p < 0.001). Applying the criteria could have safely avoided an additional 10.7% and 8.6% of EGDs in the training and validation cohorts, respectively, achieving a final value of 36.5% and 35.7% spared EGDs (0 HRV missed) compared to CT imaging with platelet count.

CONCLUSIONS

The combined DECT-based fECV score with platelet count is useful for ruling out HRV and can safely avoid more EGDs than CT imaging with platelet count.

Advances in liver US, CT, and MRI: moving toward the future

Over the past two decades, the epidemiology of chronic liver disease has changed with an increase in the prevalence of nonalcoholic fatty liver disease in parallel to the advent of curative treatments for hepatitis C. Recent developments provided new tools for diagnosis and monitoring of liver diseases based on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), as applied for assessing steatosis, fibrosis, and focal lesions. This narrative review aims to discuss the emerging approaches for qualitative and quantitative liver imaging, focusing on those expected to become adopted in clinical practice in the next 5 to 10 years. While radiomics is an emerging tool for many of these applications, dedicated techniques have been investigated for US (controlled attenuation parameter, backscatter coefficient, elastography methods such as point shear wave elastography [pSWE] and transient elastography [TE], novel Doppler techniques, and three-dimensional contrast-enhanced ultrasound [3D-CEUS]), CT (dual-energy, spectral photon counting, extracellular volume fraction, perfusion, and surface nodularity), and MRI (proton density fat fraction [PDFF], elastography [MRE], contrast enhancement index, relative enhancement, T1 mapping on the hepatobiliary phase, perfusion). Concurrently, the advent of abbreviated MRI protocols will help fulfill an increasing number of examination requests in an era of healthcare resource constraints.

Assessing the progression of segmental fibrosis in chronic liver disease using extracellular volume fractions

PURPOSE

To assess the segmental difference of liver fibrosis during the progression of chronic liver disease (CLD) using hepatic extracellular volume fractions (fECVs) obtained by dual-energy CT.

METHODS

A total of 218 patients (92 men and 126 women; mean age, 67.8 ± 11.7 years) with CLD and 85 patients (44 men and 41 women; mean age, 62.8 ± 13.7 years) without CLD as a control underwent dual-energy computed tomography (CT) of the liver (5-min equilibrium phase images). The iodine densities of the lateral, medial, anterior, and posterior segments and the aorta were measured, and fECVs were calculated. Comparisons of the fECV of each segment and for each albumin-bilirubin (ALBI) grade were then statistically analyzed.

RESULTS

In the control group and ALBI grades 1 and 3, no significant difference in fECV was found between each segment, whereas in ALBI grade 2, the fECVs were significantly larger in the medial and anterior than in the other segments (p < 0.001). The fECVs of the lateral and posterior segments significantly increased with higher ALBI grade (p < 0.001). The fECVs of the medial and anterior segments were significantly increased with higher ALBI grade, up to grade 2 (p < 0.001), but no significant difference was found between ALBI grades 2 and 3.

CONCLUSION

During the progression of CLD, fibrosis antecedently progressed in the medial and anterior segments, followed by the other liver segments.

Evaluation of liver fibrosis using hepatic extracellular volume fraction by contrast-enhanced computed tomography before and after direct-acting antiviral therapy in patients with chronic hepatitis C infection: comparison with serological liver fibrosis markers

OBJECTIVE

To evaluate time-dependent changes in hepatic extracellular volume (ECV) fraction using contrast-enhanced CT (CECT) and serological liver fibrosis markers, the fibrosis-4 (FIB-4) index and aspartate aminotransferase to platelet ratio index (APRI), before and after direct-acting antiviral therapy (DAA) for hepatitis C virus (HCV) infection.

METHODS

41 HCV-infected patients who achieved sustained virological response (SVR) after DAA (SVR group) and 10 control patients (untreated or unresponsive to treatment) who underwent CECT and serum biochemical tests before or after the first examination/DAA (T1) and at intervals thereafter (T2:<6 months after T1, T3: at 6-12 months, T4: at 12-24 months, and T5:>24 months) were evaluated.

RESULTS

In the control group, ECV fractions remained relatively unchanged through the study, and significant differences in FIB-4 index comparisons and APRI comparisons were only seen between the T2 and T4 values (p = 0.046 and p = 0.028, respectively). In the SVR group, ECV fractions were significantly different between T1 and T4 and T1 and T5 (p = 0.046 and 0.022, respectively), and both FIB-4 index and APRI were significantly different between T1 and all other time points (p = 0.017 to p < 0.001 and p = 0.001 to p < 0.001, respectively).

CONCLUSION

After DAA, ECV fraction decreased slowly, suggesting an improvement in hepatic fibrosis, while serological liver fibrosis markers decreased immediately, probably due to improvement in hepatic inflammation.

ADVANCES IN KNOWLEDGE

ECV fraction has the potential to be a non-invasive biomarker for the assessment of liver fibrosis after direct-acting antiviral therapy.

Estimation of pancreatic fibrosis and prediction of postoperative pancreatic fistula using extracellular volume fraction in multiphasic contrast-enhanced CT

OBJECTIVE

To investigate the diagnostic performance of the extracellular volume (ECV) fraction in multiphasic contrast-enhanced computed tomography (CE-CT) for estimating histologic pancreatic fibrosis and predicting postoperative pancreatic fistula (POPF).

METHODS

Eighty-five patients (49 men; mean age, 69 years) who underwent multiphasic CE-CT followed by pancreaticoduodenectomy with pancreaticojejunal anastomosis between January 2012 and December 2018 were retrospectively included. The ECV fraction was calculated from absolute enhancements of the pancreas and aorta between the precontrast and equilibrium-phase images, followed by comparisons among histologic pancreatic fibrosis grades (F0‒F3). The diagnostic performance of the ECV fraction in advanced fibrosis (F2‒F3) was evaluated using receiver operating characteristic curve analysis. Multivariate logistic regression analysis was used to evaluate the associations of the risk of POPF development with patient characteristics, histologic findings, and CT imaging parameters.

RESULTS

The mean ECV fraction of the pancreas was 34.4% ± 9.5, with an excellent intrareader agreement of 0.811 and a moderate positive correlation with pancreatic fibrosis (r = 0.476; p < 0.001). The mean ECV fraction in advanced fibrosis was significantly higher than that in no/mild fibrosis (44.4% ± 10.8 vs. 31.7% ± 6.7; p < 0.001), and the area under the receiver operating characteristic curve for the diagnosis of advanced fibrosis was 0.837. Twenty-two patients (25.9%) developed clinically relevant POPF. Multivariate logistic regression analysis demonstrated that the ECV fraction was a significant predictor of POPF.

CONCLUSIONS

The ECV fraction can offer quantitative information for assessing pancreatic fibrosis and POPF after pancreaticojejunal anastomosis.

KEY POINTS

• There was a moderate positive correlation of the extracellular volume (ECV) fraction of the pancreas in contrast-enhanced CT with the histologic grade of pancreatic fibrosis (r = 0.476; p < 0.001). • The ECV fraction was higher in advanced fibrosis (F2‒F3) than in no/mild fibrosis (F0‒F1) (p < 0.001), with an AUC of 0.837 for detecting advanced fibrosis. • The ECV fraction was an independent risk factor for predicting subclinical (odds ratio, 0.81) and clinical (odds ratio, 0.80) postoperative pancreatic fistula.

Dual-energy CT quantification of fractional extracellular space in cirrhotic patients: comparison between early and delayed equilibrium phases and correlation with oesophageal varices

OBJECTIVE

Fractional extracellular space has been validated as a marker of hepatic fibrotic in cirrhotic patients at CT-scan as well as on dual-energy CT, which takes advantage from iodine uptake. Since no consensus still exists between equilibrium phases performed at 3 or 10 min, the first aim of this work is to evaluate performances at the two different time points. Moreover, correlation between fractional extracellular space and oesophageal varices, directly related to liver fibrosis, has been assessed.

MATERIALS AND METHODS

Dual-Energy equilibrium phases at 3 and 10 min were performed within a follow-up CT-protocol scan in cirrhotic patients. Oesophageal varices were endoscopically assessed according to their size. At the two different time points, correlation between iodine density of the right and left liver lobes and correlation between the fractional extracellular space values were assessed. Correlation between fractional extracellular space and endoscopic grade of oesophageal varices was calculated.

RESULTS

No statistical differences were found between the iodine density values from the two liver lobes at the two time points (p = 0.8 at 3'; p = 0.5 at 10'). No statistical difference about fractional extracellular space estimation was found between the two time points (p = 0.17). Correlation between fractional extracellular space values and oesophageal varices was moderate (ρ = 0.45, IC 0.08-0.71, p < 0.05).

CONCLUSION

Fractional extracellular space assessed on dual-energy CT at equilibrium phases with different timing was substantially similar. The moderate correlation found between fractional extracellular space and endoscopic grade of oesophageal varices confirms that CT-scan is not currently reliable as endoscopy.

Non-invasive assessment of cirrhosis using multiphasic dual-energy CT iodine maps: correlation with model for end-stage liver disease score

PURPOSE

To determine whether multiphasic dual-energy (DE) CT iodine quantitation correlates with the severity of chronic liver disease.

METHODS

We retrospectively included 40 cirrhotic and 28 non-cirrhotic patients who underwent a multiphasic liver protocol DECT. All three phases (arterial, portal venous (PVP), and equilibrium) were performed in DE mode. Iodine (I) values (mg I/ml) were obtained by placing regions of interest in the liver, aorta, common hepatic artery, and portal vein (PV). Iodine slopes (λ) were calculated as follows: (I_equilibrium-I_arterial)/time and (I_equilibrium-I_PVP)/time. Spearman correlations between λ and MELD scores were evaluated, and the area under the curve of the receiver operating characteristic (AUROC) was calculated to distinguish cirrhotic and non-cirrhotic patients.

RESULTS

Cirrhotic and non-cirrhotic patients had significantly different λ_{equilibrium-arterial} [IQR] for the caudate (λ = 2.08 [1.39-2.98] vs 1.46 [0.76-1.93], P = 0.007), left (λ = 2.05 [1.50-2.76] vs 1.51 [0.59-1.90], P = 0.002) and right lobes (λ = 1.72 [1.12-2.50] vs 1.13 [0.41-0.43], P = 0.003) and for the PV (λ = 3.15 [2.20-5.00] vs 2.29 [0.85-2.71], P = 0.001). λ_{equilibrium-PVP} were significantly different for the right (λ = 0.11 [- 0.45-1.03] vs - 0.44 [- 0.83-0.12], P = 0.045) and left lobe (λ = 0.30 [- 0.25-0.98] vs - 0.10 [- 0.35-0.24], P = 0.001). Significant positive correlations were found between MELD scores and λ_{equilibrium-arterial} for the caudate lobe (ρ = 0.34, P = 0.004) and λ_{equilibrium-PVP} for the caudate (ρ = 0.26, P = 0.028) and right lobe (ρ = 0.33, P = 0.007). AUROC in distinguishing cirrhotic and non-cirrhotic patients were 0.72 (P = 0.002), 0.71 (P = 0.003), and 0.75 (P = 0.001) using λ_{equilibrium-arterial} for the left lobe, right lobe, and PV, respectively. The λ_{equilibrium-PVP} AUROC of the right lobe was 0.73 (P = 0.001).

CONCLUSION

Multiphasic DECT iodine quantitation over time is significantly different between cirrhotic and non-cirrhotic patients, correlates with the MELD score, and it could potentially serve as a non-invasive measure of cirrhosis and disease severity with acceptable diagnostic accuracy.

Liver fibrosis assessment with multiphasic dual-energy CT: diagnostic performance of iodine uptake parameters

OBJECTIVES

To evaluate the ability of iodine uptake parameters from hepatic multiphasic CT to predict liver fibrosis, and compare absolute contrast enhancement (ΔHU) with dual-energy iodine density (ID) methods.

METHODS

One hundred seventeen patients with pathologically proven liver fibrosis who underwent dual-energy CT during portal-venous phase (PVP) and 3-min delayed phase (DP) between January 2017 and Octotber 2019 were retrospectively included. Two radiologists measured the hepatic and blood-pool iodine uptake using ΔHU and ID methods; extracellular volume fraction (ECV) and the iodine washout rate (IWR) calculated with both methods were compared between different fibrosis stages (F0-1 vs. F2-4, F0-2 vs. F3-4, or F0-3 vs. F4). The inter-observer reproducibility (intraclass correlation coefficients [ICCs]) for ECV and IWR was compared between the ΔHU and ID methods. The areas under the receiver operating characteristic curves (AUCs) to predict liver fibrosis severity were calculated for serum and imaging fibrosis markers. To identify independent predictors, multivariable logistic regression analysis was performed, and combined performance was assessed for the ΔHU and ID models.

RESULTS

Patients with F ≥ 2 (n = 70), F ≥ 3 (n = 51), and F4 (n = 29) had higher ECV and lower IWR than those with F ≤ 1, F ≤ 2, and F ≤ 3, respectively (all p < 0.001). ICCs were higher in the ID method than in the ΔHU method (ECV: p = 0.045; IWR: p < 0.001). The AUC ranges of ECV_ΔHU, ECV_ID, IWR_ΔHU, and IWR_ID for predicting liver fibrosis severity were 0.65-0.71, 0.67-0.73, 0.76-0.81, and 0.81-0.85, respectively. IWR and fibrosis-4 index were independent predictors, with combined AUCs of 0.82-0.87 for the ΔHU model and 0.86-0.89 for the ID model.

CONCLUSIONS

IWR more accurately predicted liver fibrosis than ECV in routine multiphasic CT. The dual-energy ID method yielded higher inter-observer reproducibility and predictive values than the single-energy ΔHU method.

KEY POINTS

• The IWR calculated from hepatic iodine uptake during PVP and 3-min DP predicted liver fibrosis (AUC, 0.76-0.85), while the ECV had a relatively limited predictive value (ACU, 0.65-0.73). • Compared with the conventional ΔHU method, the dual-energy ID method provided superior inter-observer reproducibility for measurement of ECV (p = 0.046) and IWR (p < 0.001). • The IWR and FIB-4 served as independent predictors of liver fibrosis; their combination yielded the high diagnostic performance particularly when using the ID method (combined AUCs of 0.86-0.89).

Diagnosis of liver fibrosis in patients with hepatitis B-related liver disease using ultrasound with wave-number domain attenuation coefficient

BACKGROUND/AIMS

The importance of identifying the stage of liver fibrosis has motivated the development of non-invasive methods. This study aimed to evaluate the applicability of ultrasound analysis involving the wave-number domain attenuation coefficient (W-Ac) in the non-invasive quantitative differentiation of liver fibrosis.

MATERIALS AND METHODS

This was a prospective study of inpatients with hepatitis B-related liver disease treated between October 2016 and January 2018. In ultrasound, the echo from the near-field liver tissue was selected as the reference signal. The W-Ac of liver tissues was based on the fast Fourier transform of the acquired post-beamforming radio frequency signals. These values were compared with fibrosis from biopsy METAVIR score results. A receiver operating characteristic (ROC) curve tested the W-Ac method.

RESULTS

A total of 46 patients were enrolled, including 27 males and 19 females. Fibrosis was stage F0 in 12 patients, F1 in 13 patients, F2 in 10 patients, F3 in 7 patients, and F4 in 4 patients. W-Ac increased with the progression of liver fibrosis up to stage F3. There were differences between F0 and F4 stages (p<0.001) and between any 2 stages of fibrosis (p<0.05), except for stages F3 and F4. There was a significant correlation between W-Ac and METAVIR score (r=0.795, p<0.001). W-Ac differed between non-fibrosis (F0) and fibrosis (F1-F4) groups (p<0.001) and in the normal (F0), early fibrosis (F1-2), and late fibrosis groups (F3-4) (p<0.001). ROC area under the curve was 0.890, and at a cut-off of 0.12153, sensitivity was 0.706 and specificity was 0.830.

CONCLUSIONS

W-Ac allowed assessment of liver fibrosis in clinical practice.

Application of Hepatic Transit Time and Shear Wave Velocity in Assessing Portal Pressure in Patients with Cirrhotic Portal Hypertension

The aim of the study described here was to explore the value of hepatic transit time (HTT) and shear wave velocity (SWV) in diagnosing cirrhotic portal hypertension. Fifty-seven patients had undergone esophagogastric varicose vein embolization (group OBS) and 50 healthy controls (group CON) were retrospectively compared with respect to HTT (arterial-hepatic vein [HA-HVTT], portal vein-hepatic vein [PV-HVTT], liver parenchyma-hepatic vein [PA-HVTT]) and SWV to analyze their efficacy in diagnosing cirrhotic portal hypertension. The correlations between SWV/HTT and free portal pressure (FPP) in group OBS were also analyzed. Compared with group CON, group OBS had a shorter HTT and faster SWV. The area under the curve (AUC) of PV-HVTT (0.93) was higher than those of HA-HVTT (0.75) and PA-HVTT (0.64), the AUCs of PV-HVTT (0.93, threshold 7.9 s) and SWV (0.91, threshold 2.0 cm/s) did not statistically differ (z = 0.35, p = 0.73). HTT and FPP in group OBS had a negative correlation. In conclusion, HTT and SWV can be used to diagnose cirrhotic portal hypertension without difference in diagnostic efficacy, and HTT is more meaningful for assessing the changes in portal pressure.

Dual-Energy Computed Tomography of the Liver: Uses in Clinical Practices and Applications

Dual-energy computed tomography (DECT) is an imaging technique based on data acquisition at two different energy settings. Recent advances in CT have allowed data acquisitions and simultaneous analyses of X-rays at two energy levels, and have resulted in novel developments in the field of abdominal imaging. The use of low and high X-ray tube voltages in DECT provide fused images that improve the detection of liver tumors owing to the higher contrast-to-noise ratio (CNR) of the tumor compared with the liver. The use of contrast agents in CT scanning improves image quality by enhancing the CNR and signal-to-noise ratio while reducing beam-hardening artifacts. DECT can improve detection and characterization of hepatic abnormalities, including mass lesions. The technique can also be used for the diagnosis of steatosis and iron overload. This article reviews and illustrates the different applications of DECT in liver imaging.

Utility of Multiparametric CT for Identification of High-Risk NAFLD

OBJECTIVE. The purpose of this study was to evaluate the utility of laboratory and CT metrics in identifying patients with high-risk nonalcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS. Patients with biopsy-proven NAFLD who underwent CT within 1 year of biopsy were included. Histopathologic review was performed by an experienced gastrointestinal pathologist to determine steatosis, inflammation, and fibrosis. The presence of any lobular inflammation and hepatocyte ballooning was categorized as nonalcoholic steatohepatitis (NASH). Patients with NAFLD and advanced fibrosis (stage F3 or higher) were categorized as having high-risk NAFLD. Aspartate transaminase to platelet ratio index and Fibrosis-4 (FIB-4) laboratory scores were calculated. CT metrics included hepatic attenuation, liver segmental volume ratio (LSVR), splenic volume, liver surface nodularity score, and selected texture features. In addition, two readers subjectively assessed the presence of NASH (present or not present) and fibrosis (stages F0-F4). RESULTS. A total of 186 patients with NAFLD (mean age, 49 years; 74 men and 112 women) were included. Of these, 87 (47%) had NASH and 112 (60%) had moderate to severe steatosis. A total of 51 patients were classified as fibrosis stage F0, 42 as F1, 23 as F2, 37 as F3, and 33 as F4. Additionally, 70 (38%) had advanced fibrosis (stage F3 or F4) and were considered to have high-risk NAFLD. FIB-4 score correlated with fibrosis (ROC AUC of 0.75 for identifying high-risk NAFLD). Of the individual CT parameters, LSVR and splenic volume performed best (AUC of 0.69 for both for detecting high-risk NAFLD). Subjective reader assessment performed best among all parameters (AUCs of 0.78 for reader 1 and 0.79 for reader 2 for detecting high-risk NAFLD). FIB-4 and subjective scores were complementary (combined AUC of 0.82 for detecting high-risk NAFLD). For NASH assessment, FIB-4 performed best (AUC of 0.68), whereas the AUCs were less than 0.60 for all individual CT features and subjective assessments. CONCLUSION. FIB-4 and multiple CT findings can identify patients with high-risk NAFLD (advanced fibrosis or cirrhosis). However, the presence of NASH is elusive on CT.

Noninvasive Staging of Liver Fibrosis Using 5-Minute Delayed Dual-Energy CT: Comparison with US Elastography and Correlation with Histologic Findings

Background Normalized iodine concentration (NIC) (ratio of iodine concentration of liver to that of aorta) of liver at delayed dual-energy CT (DECT) may reflect the amount of fibrosis based on the extent of iodine uptake. Purpose To stage liver fibrosis by using 5-minute delayed DECT and compare findings with those of transient elastography (TE), shear-wave elastography (SWE), and histologic examination. Materials and Methods This prospective study included patients with chronic liver disease who were scheduled to undergo multiphase abdominal CT and liver biopsy from January 2017 to September 2018. Fifty individuals being screened as renal donors comprised the control group. Study participants underwent TE, SWE, multiphasic DECT (including 5-minute delayed dual-energy scanning), and liver biopsy. Multiphasic DECT and SWE were performed in the control group. The NIC of the right lobe of the liver (RNIC) was compared with liver stiffness (LS) as measured with TE and SWE and with the METAVIR fibrosis stage (ranging from F0 to F4). Diagnostic performance was assessed by using areas under the receiver operating characteristic curve (AUCs). Results A total of 107 participants (mean age, 35 years ± 12 [standard deviation]; 57 men) and 50 control subjects (mean age, 47 years ± 11; 29 women) were evaluated. The RNIC showed strong correlation with METAVIR stage (Spearman ρ = 0.81, P < .001). The AUC for RNIC with each METAVIR stage ranged between 0.86 (95% CI: 0.76, 0.97) and 0.96 (95% CI: 0.92, 0.99). The cut-off value of RNIC was 0.24 (sensitivity: 85% [86 of 101 participants; 95% CI: 77%, 91%]; specificity: 83% [84 of 101 participants; 95% CI: 42%, 98%]) for stage F1 fibrosis and 0.29 (sensitivity: 84% [67 of 80 participants; 95% CI: 74%, 90%]; specificity: 81% [65 of 80 participants; 95% CI: 63%, 92%]) for stage F2 fibrosis. RNIC correlated well with LS as measured with TE and SWE (Spearman ρ = 0.60 and 0.64, respectively; P < .001). Conclusion Normalized iodine concentration of liver at 5-minute delayed dual-energy CT showed strong correlation with the histologic stages of liver fibrosis and good diagnostic performance in estimating liver fibrosis. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Chandarana and Shanbhogue in this issue.

Dual-energy CT in diffuse liver disease: is there a role?

Dual-energy CT (DECT) can be defined as the use of two different energy levels to identify and quantify material composition. Since its inception, DECT has benefited from remarkable improvements in hardware and clinical applications. DECT enables accurate identification and quantification of multiple materials, including fat, iron, and iodine. As a consequence, multiple studies have investigated the potential role of DECT in the assessment of diffuse liver diseases. While this role is evolving, this article aims to review the most relevant literature on use of DECT for assessment of diffuse liver diseases. Moreover, the basic concepts on DECT techniques, types of image reconstruction, and DECT-dedicated software will be described, focusing on the areas that are most relevant for the evaluation of diffuse liver diseases. Also, we will review the evidence of added value of DECT in detection and assessment of hepatocellular carcinoma which is a known risk in patients with diffuse liver disease.

Liver extracellular volume fraction values obtained with magnetic resonance imaging can quantitatively stage liver fibrosis: a validation study in monkeys with nonalcoholic steatohepatitis

OBJECTIVES

This study was to evaluate the diagnostic value of liver extracellular volume (LECV) for the staging of liver fibrosis in a cynomolgus monkey model of nonalcoholic steatohepatitis (NASH).

METHODS

Forty-eight cynomolgus monkeys were enrolled in this prospective study. There are 17 healthy monkeys and 31 monkeys with NASH. Ten of these monkeys were used for repeatability assessment. The remaining 38 monkeys were used to compare LECV with other indicators including pathology fibrosis score, native T1, and serum chemical indexes by Spearman, Pearson correlation test, and ROC curves. The inter-reader variability was assessed by interclass correlation. The repeatability measurement of LECV was analyzed using Bland-Altman plots and the coefficient of variation. Partial correlation analysis was performed to assess the effects of fat content and inflammation scores on the correlation between LECV/T1 and liver fibrosis score.

RESULTS

This study demonstrated a good intra-reader agreement (intraclass correlation = 0.79) of LECV in all monkeys and an excellent repeatability in 10 monkeys (coefficient of variation = 2.01%). The LECV has a strong correlation with the fibrosis score (r = 0.949; p < 0.0001), low-density lipoprotein (r = 0.72; p < 0.0001), and cholesterol (r = 0.70; p < 0.0001). LECV showed high diagnostic efficacy in the diagnosis of liver fibrosis (area under the curve of ROC, 0.945~1; p < 0.001).

CONCLUSIONS

LECV may serve as a noninvasive valuable biomarker for the quantification and differentiating of the non-severe liver fibrosis (stage ≤ F3). However, circulating serum markers low-density lipoprotein and cholesterol (CHO) may not serve for this purpose.

KEY POINTS

• This paper demonstrated the excellent repeatability (intraclass correlation coefficient = 0.79) of LECV in monkey animal model. • LECV-MRI has a strong correlation with histopathological fibrosis score stage (r = 0.949; p < 0.0001) and shows high diagnostic efficacy in the staging of non-severe liver fibrosis (the area under ROC curve ≥ 0.945). • The new fibrosis score maps appeared to provide a better imaging tool for the spatial assessment of liver fibrosis. It may eventually facilitate the diagnosis of liver fibrosis distribution.

Dual-source dual-energy CT in the evaluation of hepatic fractional extracellular space in cirrhosis

BACKGROUND

One of the main features of liver fibrosis is the expansion of the interstitial space. All water-soluble CT contrast agents remain confined in the vascular and interstitial space constituting the fractional extracellular space (fECS). Indirect measure of its expansion can be quantified during equilibrium phase with CT. The goal of this prospective study was to assess the feasibility of dual-energy CT (DECT) with iodine quantification at equilibrium phase in the evaluation of significant fibrosis or cirrhosis.

METHODS

Thirty-eight cirrhotic patients (according to Child-Pugh and MELD scores), scheduled for liver CT, were enrolled in the study group. Twenty-four patients undergoing CT urography with a 10-min excretory phase were included in the control group. fECS was calculated as the ratio of the iodine concentration of liver parenchyma to that of the aorta, multiplied by 1 minus hematocrit.

RESULTS

Final study and control group were, respectively, composed of 22 and 20 patients. Mean hepatic fECS value was statistically greater in study group (P < 0.05). Positive correlation was observed between hepatic fECS value and MELD score (r = 0.64, P < 0.05). Analysis of variance showed statistical differences between control group and the Child-Pugh grades and between Child-Pugh A and B patients and Child-Pugh C patients (P < 0.05). ROC curves analysis yielded an optimum fECS cutoff value of 26.3% for differentiation of control group and cirrhotic patients (AUC 0.88; 86% sensitivity, 85% specificity).

CONCLUSIONS

Dual-source DECT is a feasible, noninvasive method for the assessment of significant liver fibrosis or cirrhosis.

A Responsive Magnetic Resonance Imaging Contrast Agent for Detection of Excess Copper(II) in the Liver In Vivo

The design, synthesis, and properties of a new gadolinium-based copper-responsive magnetic resonance imaging (MRI) contrast agent is presented. The sensor (GdL₁) has high selectivity for copper ions and exhibits a 43% increase in r₁ relaxivity (20 MHz) upon binding to 1 equiv of Cu²⁺ in aqueous buffer. Interestingly, in the presence of physiological levels of human serum albumin (HSA), the r₁ relaxivity is amplified further up to 270%. Additional spectroscopic and X-ray absorption spectroscopy (XAS) studies show that Cu²⁺ is coordinated by two carboxylic acid groups and the single amine group on an appended side chain of GdL₁ and forms a ternary complex with HSA (GdL₁-Cu²⁺-HSA). T₁-weighted in vivo imaging demonstrates that GdL₁ can detect basal, endogenous labile copper(II) ions in living mice. This offers a unique opportunity to explore the role of copper ions in the development and progression of neurological diseases such as Wilson's disease.

A comparative study of MR extracellular volume fraction measurement and two-dimensional shear-wave elastography in assessment of liver fibrosis with chronic hepatitis B

OBJECTIVE

To evaluate the value of MR liver extracellular volume (ECV_liver) in assessment of liver fibrosis with chronic hepatitis B (CHB), and to compare its performance with two-dimensional (2D) shear-wave elastography (SWE).

MATERIALS AND METHODS

A total of 68 CHB patients who were histologically diagnosed as fibrosis stages F0 to F4 were retrospectively analyzed. All patients underwent gadopentetate dimeglumine-enhanced T1-mapping and 2D SWE. ECV_liver and liver stiffness were measured and compared between fibrosis subgroups; their correlations with histologic findings were evaluated using Spearman correlation test and multiple regression analysis. Diagnostic performance in evaluating liver fibrosis stages was assessed and compared using receiver-operating characteristic analysis.

RESULTS

Both ECV_liver and liver stiffness increased as the fibrosis score increased (F = 17.08 to 10.99, P < 0.001). ECV_liver displayed a strong correlation with fibrosis stage (r = 0.740, P < 0.001), and liver stiffness displayed a moderate correlation (r = 0.651, P < 0.001); multivariate analysis revealed that only ECV_liver was independently correlated with fibrosis stage (P < 0.001). Univariate analyses showed significant correlations of ECV_liver with fibrosis stage, inflammatory activity, and platelet count; among all, the fibrosis stage had the highest correlation coefficient and was the only independent factor (P < 0.001). Overall, ECV_liver had no significant different performance compared with 2D SWE for the identification of both fibrosis stage s ≥ F2 and F4 (P = 0.868 and 0.171).

CONCLUSION

MR ECV_liver plays a promising role in the prediction of liver fibrosis for patients with CHB, comparable to 2D SWE.

Assessing liver fibrosis in chronic hepatitis B using MR extracellular volume measurements: Comparison with serum fibrosis indices

OBJECTIVES

To evaluate the diagnostic value of liver extracellular volume (ECV_liver) measurement by equilibrium MR in staging liver fibrosis in chronic hepatitis B (CHB) patients, and to compare its performance with serum fibrosis indices.

MATERIALS AND METHODS

91 CHB patients were included and underwent gadopentetate dimeglumine-enhanced MRI with T1 mapping sequence before and 15-min after contrast. ECV_liver, aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis index based on the four factors (FIB-4) were calculated and compared between fibrosis subgroups, and the correlations between the three indices and fibrosis stage or inflammatory activity were measured by Spearman correlation analysis and stepwise multiple regression analysis. Diagnostic performance in evaluating liver fibrosis stage was assessed and compared using receiver operating characteristic analysis.

RESULTS

Interobserver agreement showed an excellent interclass correlation coefficient of 0.895 for ECV_liver. ECV_liver, APRI and FIB-4 were different between fibrosis stages as a whole (F/H = 18.44-24.36, P ≤ 0.001). ECV_liver had the strongest correlation with fibrosis stage (r = 0.727, P < 0.001), while APRI and FIB-4 had weak correlations (r = 0.466 and 0.440, P < 0.001). Multivariate analysis showed that only ECV_liver was independently correlated with fibrosis stage (P < 0.001). The fibrosis stage was the only independent factor correlated with ECV_liver comparing to inflammatory activity (P < 0.001). AUCs of ECV_liver were larger than both APRI and FIB-4 in fibrosis staging, with significant differences in the diagnosis of advanced fibrosis (≥F3) and cirrhosis (F4) (P = 0.0024 to 0.0049).

CONCLUSION

MR ECV_liver provides a promising noninvasive tool in staging liver fibrosis for CHB patients, superior to the fibrosis indices of APRI and FIB-4.

Dual-energy computed tomography for non-invasive staging of liver fibrosis: Accuracy of iodine density measurements from contrast-enhanced data

AIM

To investigate whether iodine density measurements from contrast-enhanced dual-energy computed tomography (CT) data can non-invasively stage liver fibrosis.

METHODS

This single-center, prospective study was approved by our IRB with written informed consent. Forty-seven consecutive patients (26 men and 21 women; mean age, 63.1 years) with chronic liver disease underwent contrast-enhanced dual-energy CT of the liver (non-contrast, arterial, portal venous, and equilibrium phase images), followed by liver biopsy. Iodine density of liver and aorta were obtained by two independent observers. Iodine uptake of the liver (Δ Liver), representing the difference in iodine density between equilibrium phase and non-contrast images, was calculated and normalized by aorta (Δ Liver/Aorta). We accounted for contrast agent distribution volume by using hematocrit level. Accuracy of iodine density measurements for staging liver fibrosis was assessed by using receiver operating characteristic (ROC) curves. Multivariate linear regression analysis was used to assess the impact of independent variables (liver fibrosis stage and patient-related confounders) on iodine uptake.

RESULTS

The Δ Liver/Aorta significantly increased and moderately correlated with METAVIR liver fibrosis stage (ρ = 0.645, P < 0.001). Areas under the ROC curve ranged from 0.795 to 0.855 for discriminating each liver fibrosis score (≥F1-F4). METAVIR fibrosis stage was the most significant independent factor associated with Δ Liver (P = 0.005) and Δ Liver/Aorta (P < 0.001).

CONCLUSION

Hepatic extracellular volume fraction with contrast-enhanced dual-energy CT can non-invasively stage liver fibrosis in chronic liver diseases. This technique could prove useful for monitoring disease progression and treatment response, potentially reducing the need for liver biopsy.

CT texture analysis of the liver for assessing hepatic fibrosis in patients with hepatitis C virus

OBJECTIVE

To evaluate CT texture analysis (CTTA) for non-invasively staging of hepatic fibrosis (stages F0-F4) in a cohort of patients with hepatitis C virus (HCV).

METHODS

Quantitative texture analysis of the liver was performed on abdominal multidimensional CT scans. Single slice region of interest measurements of the total liver, Couinaud segments IV-VIII and segments I-III were made. CT texture parameters were tested against stage of hepatic fibrosis in segments IV-VIII on the portal venous phase. Texture parameters were correlated with biopsy performed within 1 year for all cases with intermediate fibrosis (F0-F3).

RESULTS

CT scans of 556 adults (360 males, 196 females; mean age, 49.8 years), including a healthy control group (F0, n = 77) and patients with hepatitis C virus and Stage 0 disease (n = 49), and patients with increasing stages of fibrosis (F1, n = 80; F2 n = 99; F3 n = 87; F4 n = 164) were evaluated. Mean gray level intensity increased with increasing fibrosis. For significant fibrosis (≥F2), mean showed receiver operatingcharacteristic area under the curve (AUC) of 0.80 with sensitivity and specificity of 74 and 75% using a threshold of 0.44, with similar receiver operatingcharacteristic AUC and sensitivity/specificity for advanced fibrosis (≥F3). Skewness and kurtosis were inversely associated with hepatic fibrosis, most prominently in cirrhotic patients. A multivariate model combining these four texture features (mean, mpp, skewness and kurtosis) showed slightly improved performance with AUC of 0.82, 0.82 and 0.86 for any fibrosis (F0 vs F1-F4), significant fibrosis (F0-1 vs F2-4) and advanced fibrosis (F0-2 vs F3-4) respectively.

CONCLUSION

CT texture features may be associated with hepatic fibrosis and have utility in staging fibrosis, particularly at advanced levels.

ADVANCES IN KNOWLEDGE

CTTA may be helpful in detecting and staging hepatic fibrosis, particularly at advanced levels. CT measures like CTTA can be retrospectively evaluated without special equipment.

Multidetector Computed Tomography for Retrospective, Noninvasive Staging of Liver Fibrosis

Although not traditionally used to assess hepatic fibrosis, computed tomography (CT) is fast, accessible, robust, and commonly used for abdominal indications. CT metrics are often easily retrospectively obtained without special equipment. Metrics such as liver segmental volume ratio, which quantifies regional hepatic volume changes; splenic volume; and liver surface nodularity scoring show diagnostic performance comparable to elastography techniques for detecting significant and advanced fibrosis. Other emerging CT tools, such as CT texture analysis and fractional extracellular volume, have also shown promise in identifying fibrosis and warrant further study.

Imaging of nonalcoholic fatty liver disease and its clinical utility

The prevalence of nonalcoholic fatty liver disease has been continuously rising over the last three decades and is projected to become the most common indication for liver transplantation in the near future. Its pathophysiology and complex interplay with diabetes and the metabolic syndrome are not as yet fully understood despite growing scientific interest and research. Modern imaging techniques offer significant assistance in this field by enabling the study of the liver noninvasively and evaluation of the degree of both steatosis and fibrosis, and even in attempting to diagnose the presence of inflammation (steatohepatitis). The derived measurements are highly precise, accurate and reproducible, performing better than biopsy in terms of quantification. In this article, these imaging techniques are overviewed and their performance regarding diagnosis, stratification and monitoring are evaluated. Their expanding role both in the research arena and in clinical practice along with their limitations is also discussed.

Evaluation of hepatic fibrosis: a review from the society of abdominal radiology disease focus panel

Hepatic fibrosis is potentially reversible; however early diagnosis is necessary for treatment in order to halt progression to cirrhosis and development of complications including portal hypertension and hepatocellular carcinoma. Morphologic signs of cirrhosis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) alone are unreliable and are seen with more advanced disease. Newer imaging techniques to diagnose liver fibrosis are reliable and accurate, and include magnetic resonance elastography and US elastography (one-dimensional transient elastography and point shear wave elastography or acoustic radiation force impulse imaging). Research is ongoing with multiple other techniques for the noninvasive diagnosis of hepatic fibrosis, including MRI with diffusion-weighted imaging, hepatobiliary contrast enhancement, and perfusion; CT using perfusion, fractional extracellular space techniques, and dual-energy, contrast-enhanced US, texture analysis in multiple modalities, quantitative mapping, and direct molecular imaging probes. Efforts to advance the noninvasive imaging assessment of hepatic fibrosis will facilitate earlier diagnosis and improve patient monitoring with the goal of preventing the progression to cirrhosis and its complications.