The evaluation of haemodynamics in cirrhotic patients with spectral CT

Spectral CT: Current Liver Applications

Using two different energy levels, dual-energy computed tomography (DECT) allows for material differentiation, improves image quality and iodine conspicuity, and allows researchers the opportunity to determine iodine contrast and radiation dose reduction. Several commercialized platforms with different acquisition techniques are constantly being improved. Furthermore, DECT clinical applications and advantages are continually being reported in a wide range of diseases. We aimed to review the current applications of and challenges in using DECT in the treatment of liver diseases. The greater contrast provided by low-energy reconstructed images and the capability of iodine quantification have been mostly valuable for lesion detection and characterization, accurate staging, treatment response assessment, and thrombi characterization. Material decomposition techniques allow for the non-invasive quantification of fat/iron deposition and fibrosis. Reduced image quality with larger body sizes, cross-vendor and scanner variability, and long reconstruction time are among the limitations of DECT. Promising techniques for improving image quality with lower radiation dose include the deep learning imaging reconstruction method and novel spectral photon-counting computed tomography.

The evaluation of portal hypertension in cirrhotic patients with spectral computed tomography

BACKGROUND

Iodine concentrations measured using dual-energy spectral CT (DESCT) have been recently proposed as providing good performance for examining tissues hemodynamics.

PURPOSE

To evaluate the diagnostic efficacy of DESCT-derived parameters in evaluating portal venous pressure in patients with liver cirrhosis.

MATERIAL AND METHODS

A total of 71 patients with liver cirrhosis who underwent percutaneous transhepatic portal vein puncture procedures were included in this study. All participants underwent DESCT and gastrointestinal endoscopy within one month before the operation. The direct portal venous pressure of each participant was measured preoperatively.

RESULTS

Stepwise multivariate linear regression analysis showed that the iodine concentrations in the portal vein and hepatic parenchyma during the portal venous phase and the platelet count were independently correlated with the direct portal venous pressure (P < 0.001, P < 0.001, and P = 0.030, respectively). Receiver operating characteristic analysis revealed that the normalized iodine concentration of the hepatic parenchyma had the best performance for identifying clinically significant portal hypertension (≥10 mmHg), esophageal varices, and high-risk esophageal varices (the area under the curve values were 0.951, 0.932, and 0.960, respectively).

CONCLUSION

The normalized iodine concentration of the hepatic parenchyma is a reliable parameter to non-invasively assess portal venous pressure in patients with liver cirrhosis.

Effect of intravenous iodinated contrast administration on diagnostic ability for osteoporosis using CT attenuation measurement in patients with liver cirrhosis

OBJECTIVES

To evaluate the influence of intravenous contrast agent on the diagnostic ability for osteoporosis using CT attenuation measurement in patients with liver cirrhosis.

METHODS

This retrospective study was approved by our institutional review board and informed consent was waived. 208 patients with liver cirrhosis (mean age, 61.25 years ± 9.43 [standard deviation]; range, 30-82 years) who underwent both unenhanced and two contrast-enhanced (arterial and venous phase) abdominal dual-energy CT examinations from January 1 to September 1, 2020, were recruited. CT attenuation values were measured in the medullary compartment of vertebral body (L1-L3) and bone mass was determined by the hydroxyapatite concentration obtained in dual-energy spectral CT and used as the reference standard. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic ability of using CT attenuation number in unenhanced, arterial, and venous phases.

RESULTS

Area under ROC curve using unenhanced CT attenuation was different from using arterial CT attenuation (p= 0.038) and venous CT attenuation (p = 0.048) to diagnosing osteoporosis. However, there was no significant difference between unenhanced CT attenuation and arterial CT attenuation (p = 0.773) and between unenhanced CT attenuation and venous CT attenuation (p = 0.746) to distinguish low bone mass (osteoporosis or osteopenia).

CONCLUSIONS

The diagnostic ability for osteoporosis using CT attenuation measurement in contrast-enhanced scans is decreased due to intravenous contrast contamination, however, which had no influence on the diagnostic ability of CT attenuation for low bone mass (osteoporosis or osteopenia).

ADVANCES IN KNOWLEDGE

The diagnostic ability of using enhanced CT attenuation values for osteoporosis decreased compared to unenhanced CT attenuation values.

Establishment of a non-invasive prediction model for the risk of oesophageal variceal bleeding using radiomics based on CT

AIM

To establish a non-invasive prediction model for the risk of oesophageal variceal bleeding (OVB) using radiomics based on computed tomography (CT).

MATERIALS AND METHODS

The study included 317 patients, 69 of whom were OVB-positive and 248 were OVB-negative. The OVB was caused by cirrhosis associated with hepatitis B. All patients underwent both oesophagogastroduodenoscopy (OGD) and triple-phase contrast-enhanced CT with spectral imaging mode within 14 days before OGD. The patients were divided chronologically into training (n=222) and validation (n=95) cohorts at a ratio of 7:3. The clinical and CT features were collected from a picture archiving and communication system, and radiomics features were extracted from the portal venous phase CT. Spearman's correlation, least absolute shrinkage, and selection operator regression analyses were used to select the most correlated features. Models were built using the selected features. The predictive performance of the models was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

One clinical feature, five CT features, and three radiomics features were selected, and three non-invasive models were built. Integration of the radiomics, CT, and clinical features model showed a better performance in predicting the risk of OVB, with an AUC of 0.89 (95% confidence interval [CI], 0.84-0.94) in the training dataset and 0.78 (95% CI, 0.68-0.87) in the validation dataset.

CONCLUSION

The combination of radiomics, CT, and clinical features may have added value in the non-invasive prediction of OVB, enabling early prevention and treatment.

Dual-energy computed tomography for non-invasive prediction of the risk of oesophageal variceal bleeding with hepatitis B cirrhosis

OBJECTIVE

Oesophageal variceal bleeding (OVB) is a fatal complication of cirrhosis and/or portal hypertension. We aimed to develop a non-invasive prediction model for the risk of OVB using dual-energy computed tomography (CT).

METHODS

317 oesophageal varices (OV) patients with hepatitis B virus-related cirrhosis were retrospectively assessed from January 2018 to December 2018. All patients underwent dual-energy CT scans within 14 days before endoscopy. 222 of 317 patients (174 OVB-negative patients and 48 OVB-positive patients) were included in the training cohort and 95 patients (74 OVB-negative patients and 21 OVB-positive patients) were included in the validation cohort chronologically. A model with the selected conventional CT features and a model with the conventional CT and dual-energy CT features were developed. The prediction accuracy was evaluated using the receiver operating characteristic (ROC) curve. The accuracy and reproducibility of the models for OVB risk prediction of cirrhosis were validated by the validation cohort. The areas under the curve (AUC) of the two models were compared with Delong test.

RESULTS

Diameter of oesophageal vein (OV(mm)), diameter of splenic vein (SPV(mm)), ascites (AS), iodine concentration in short gastric vein (SGV(HU)), iodine concentration in spleen (SP(HU)) were independent predictors of OVB risk (P < 0.05). Then, we developed a model with the selected conventional CT features [OV(mm), SPV(mm), AS] and a model with the conventional CT and dual-energy CT features [OV(mm), SPV(mm), AS, SGV(HU), SP(HU)]. The AUCs of the model built with the conventional CT and dual-energy CT features were higher than the model built only with the conventional CT features in the training (0.839 vs 0.809) and validation cohorts (0.798 vs 0.738).

CONCLUSION

The non-invasive prediction model developed with the conventional CT and dual-energy CT features may have added value in noninvasively predicting OVB than the model built only with the conventional CT features and may have significant clinical implications on early prevention and treatment of OVB.

ADVANCES IN KNOWLEDGE

Combination of dual-energy CT with conventional CT may have added value for non-invasive prediction of OVB compared to conventional CT.

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).

Spectral CT in Lung Cancer: Usefulness of Iodine Concentration for Evaluation of Tumor Angiogenesis and Prognosis

OBJECTIVE. The purpose of this study was to investigate the correlation between iodine concentration (IC) derived from spectral CT and angiogenesis and the relationships between IC and clinical-pathologic features associated with lung cancer prognosis. SUBJECTS AND METHODS. Sixty patients with lung cancer were enrolled and underwent spectral CT. The IC, IC difference (ICD), and normalized IC (NIC) of tumors were measured in the arterial phase, venous phase (VP), and delayed phase. The microvessel densities (MVDs) of CD34-stained specimens were evaluated. Correlation analysis was performed for IC and MVD. The relationships between the IC index showing the best correlations with MVD and clinical-pathologic findings of pathologic types, histologic differentiation, tumor size, lymph node status, pathologic TNM stage, and intratumoral necrosis were investigated. RESULTS. The mean (± IQR) MVD of all tumors was 42.00 ± 27.50 vessels per field at ×400 magnification, with two MVD distribution types. The MVD of lung cancer correlated positively with the IC, ICD, and NIC on three-phase contrast-enhanced scanning (r range, 0.581-0.800; all p < 0.001), and the IC in the VP showed the strongest correlation with MVD (r = 0.800; p < 0.001). The correlations between IC and MVD, ICD and MVD, and NIC and MVD varied depending on whether the same scanning phase or same IC index was used. The IC in the VP showed statistically significant differences in the pathologic types of adenocarcinoma and squamous cell carcinoma, histologic differentiation, tumor size, and status of intratumoral necrosis of lung cancer (p < 0.05), but was not associated with nodal metastasis and pathologic TNM stages (p > 0.05). CONCLUSION. IC indexes derived from spectral CT, especially the IC in the VP, were useful indicators for evaluating tumor angiogenesis and prognosis.

Assessing Liver Hemodynamics in Children With Cholestatic Cirrhosis by Use of Dual-Energy Spectral CT

OBJECTIVE. The purpose of this study was to evaluate the value of dual-energy CT (DECT) in assessing liver hemodynamics in children with cholestatic cirrhosis. MATERIALS AND METHODS. The cases of 60 children with cholestatic cirrhosis (study group) and 15 children with inherited metabolic diseases but normal liver function (control group) were retrospectively evaluated. Enhanced CT scans were obtained in spectral imaging mode. Iodine concentration (IC) of hepatic parenchyma in the arterial phase (IC_A) and portal venous phase (IC_P) was measured on iodine-water material decomposition images. The hepatic arterial iodine fraction (AIF) was calculated as: AIF = IC_A / IC_P. The IC_A, IC_P, and AIF of children in the control and study groups were analyzed by one-way ANOVA and post hoc test with Bonferroni correction. The radiation dose was recorded. RESULTS. There were differences in IC_A and AIF between the control and study groups. The values in patients in the Child-Pugh class C group were the highest and those in the control group the lowest (p < 0.05). Statistically significant differences in IC_P were not found (p > 0.05). Specifically, the multiple comparison results indicated that there were differences in both IC_A and AIF in most of the groups (p < 0.05). The volume CT dose index value for all patients was the same at 10.14 mGy for each enhanced phase, and the total dose-length product varied between 402.68 and 679.18 mGy-cm. CONCLUSION. IC_A and AIF obtained at dual-energy CT can be used as semiquantitative indicators to evaluate the liver hemodynamics of children with cholestatic cirrhosis.

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.

Noninvasive Assessment of Portal Hypertension Using Spectral Computed Tomography

BACKGROUND

Early diagnosis of portal hypertension is imperative for timely treatment to reduce the mortality rate. However, there is still no adequate method to noninvasively and accurately assess the portal hypertension in routine clinical practice.

PURPOSE

We aimed to evaluate the accuracy of parameters measured using dual energy spectral computed tomography (LightSpeed CT750 HD) in assessing portal venous pressure in patients with liver cirrhosis.

STUDY

Forty-five patients with liver cirrhosis who underwent percutaneous transhepatic portal vein puncture as part of their treatment for liver disease were enrolled in this study. Measurement of direct portal venous pressure was performed preoperatively. All patients underwent dual energy spectral computed tomography within 3 days before their operations.

RESULTS

The iodine concentrations of portal vein and hepatic parenchyma during the portal venous phase and the alanine aminotransferase level were found to be independently correlated with the direct portal venous pressure according to stepwise multivariate linear regression analysis (P<0.001, 0.004, and 0.024, respectively). In a receiver operating characteristic analysis, the area under the receiver operating characteristic of iodine concentrations of the portal vein (ICPV) for identifying clinically significant portal hypertension (≥10 mm Hg) was significantly higher than that of iodine concentrations of hepatic parenchyma (ICliver) and the alanine aminotransferase level (0.944, 0.825, and 0.301, respectively). The threshold ICPV of 58.27 yielded a sensitivity of 93.8%, specificity of 69.2%, positive predictive value of 88.2%, and negative predictive value of 81.8%, respectively.

CONCLUSIONS

ICPV values may be a useful tool in noninvasively assessing the portal venous pressure and identifying clinically significant portal hypertension in liver cirrhosis.

Iodine Concentration in Spectral CT: Assessment of Prognostic Determinants in Patients With Gastric Adenocarcinoma

OBJECTIVE

The purpose of this study was to use virtual monochromatic spectral CT to investigate the usefulness of iodine concentration (IC) and its correlation with clinicopathologically determined prognostic factors in gastric adenocarcinoma.

SUBJECTS AND METHODS

From June 2012 to March 2015, 34 patients with gastric adenocarcinoma underwent arterial and portal venous phase spectral CT. The ICs in the arterial and portal venous phases were calculated and then normalized with the aorta as normalized IC (NIC). The surgical specimen was evaluated with CD34 staining to determine microvessel density (MVD). The correlation between imaging results and clinicopathologic findings was investigated for histologic grading, lymph node metastasis, serosal involvement, distant metastasis, pathologic TNM stage, and MVD.

RESULTS

The mean arterial phase NIC value of tumors was 0.12 ± 0.03, portal venous phase NIC value was 0.39 ± 0.06, and MVD was 26.94 ± 7.87 vessels per high-power field (×400). Both arterial phase and portal venous phase NIC values were significantly higher in poorly differentiated gastric adenocarcinomas (p = 0.005) than in moderately differentiated tumors (p = 0.013). There was no significant correlation between NIC and serosal involvement or distant metastasis. There was significant correlation between the NIC and MVD in gastric adenocarcinoma (arterial phase NIC, p = 0.013; portal venous phase NIC, p = 0.001). However, neither the arterial nor the portal venous phase NIC of gastric adenocarcinoma had a significant relation to lymphatic metastasis or pathologic TNM stage. There was a significant difference between the high and low MVD groups with respect to portal venous phase NIC (p = 0.045).

CONCLUSION

NIC can serve as a useful predictor of angiogenesis and degree of differentiation of moderately and poorly differentiated gastric adenocarcinomas.

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.