Perfusion computed tomography for detection of hepatocellular carcinoma in patients with liver cirrhosis

Advances in gross tumor target volume determination in radiotherapy for patients with hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is one of the most common malignant neoplasms. With the advancement of technology, the precision of radiotherapy (RT) for HCC has considerably increased, and it is an indispensable modality in the comprehensive management of HCC. Some RT techniques increase the radiation dose to HCC, which decreases the radiation dose delivered to the surrounding normal liver tissue. This approach significantly improves the efficacy of HCC treatment and reduces the incidence of Radiation-induced Liver Disease (RILD). Clear imaging and precise determination of the Gross Target Volume (GTV) are prerequisites of precise RT of HCC. The main hindrances in determining the HCC GTV include indistinct tumor boundaries on imaging and the impact on respiratory motion. The integration of multimodal imaging, four-dimensional imaging, and artificial intelligence (AI) techniques can help overcome challenges for HCC GTV. In this article, the advancements in medical imaging and precise determination for HCC GTV have been reviewed, providing a framework for the precise RT of HCC.

Hepatocellular carcinoma: State of the art diagnostic imaging

Primary liver cancer is the fourth most common malignancy worldwide, with hepatocellular carcinoma (HCC) comprising up to 90% of cases. Imaging is a staple for surveillance and diagnostic criteria for HCC in current guidelines. Because early diagnosis can impact treatment approaches, utilizing new imaging methods and protocols to aid in differentiation and tumor grading provides a unique opportunity to drastically impact patient prognosis. Within this review manuscript, we provide an overview of imaging modalities used to screen and evaluate HCC. We also briefly discuss emerging uses of new imaging techniques that offer the potential for improving current paradigms for HCC characterization, management, and treatment monitoring.

Radiological findings in non-surgical recurrent hepatocellular carcinoma: From locoregional treatments to immunotherapy

Since hepatocellular carcinoma (HCC) represents an important cause of mortality and morbidity all over the world. Currently, it is fundamental not only to achieve a curative treatment but also to manage in the best way any possible recurrence. Even if the latest update of the Barcelona Clinic Liver Cancer guidelines for HCC treatment has introduced new locoregional techniques and confirmed others as well-established clinical practices, there is still no consensus about the treatment of recurrent HCC (RHCC). Locoregional treatments and medical therapy represent two of the most widely accepted approaches for disease control, especially in the advanced stage of liver disease. Different medical treatments are now approved, and others are under investigation. On this basis, radiology plays a central role in the diagnosis of RHCC and the assessment of response to locoregional treatments and medical therapy for RHCC. This review summarized the actual clinical practice by underlining the importance of the radiological approach both in the diagnosis and treatment of RHCC.

Current Imaging Diagnosis of Hepatocellular Carcinoma

Simple Summary

The role of imaging in the management of hepatocellular carcinoma (HCC) has significantly evolved and expanded beyond the plain radiological confirmation of the tumor based on the typical appearance in a multiphase contrast-enhanced CT or MRI examination. The introduction of hepatobiliary contrast agents has enabled the diagnosis of hepatocarcinogenesis at earlier stages, while the application of ultrasound contrast agents has drastically upgraded the role of ultrasound in the diagnostic algorithms. Newer quantitative techniques assessing blood perfusion on CT and MRI not only allow earlier diagnosis and confident differentiation from other lesions, but they also provide biomarkers for the evaluation of treatment response. As distinct HCC subtypes are identified, their correlation with specific imaging features holds great promise for estimating tumor aggressiveness and prognosis. This review presents the current role of imaging and underlines its critical role in the successful management of patients with HCC.

Abstract

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer related death worldwide. Radiology has traditionally played a central role in HCC management, ranging from screening of high-risk patients to non-invasive diagnosis, as well as the evaluation of treatment response and post-treatment follow-up. From liver ultrasonography with or without contrast to dynamic multiple phased CT and dynamic MRI with diffusion protocols, great progress has been achieved in the last decade. Throughout the last few years, pathological, biological, genetic, and immune-chemical analyses have revealed several tumoral subtypes with diverse biological behavior, highlighting the need for the re-evaluation of established radiological methods. Considering these changes, novel methods that provide functional and quantitative parameters in addition to morphological information are increasingly incorporated into modern diagnostic protocols for HCC. In this way, differential diagnosis became even more challenging throughout the last few years. Use of liver specific contrast agents, as well as CT/MRI perfusion techniques, seem to not only allow earlier detection and more accurate characterization of HCC lesions, but also make it possible to predict response to treatment and survival. Nevertheless, several limitations and technical considerations still exist. This review will describe and discuss all these imaging modalities and their advances in the imaging of HCC lesions in cirrhotic and non-cirrhotic livers. Sensitivity and specificity rates, method limitations, and technical considerations will be discussed.

CT hepatic arterial perfusion index does not allow stratification of the degree of esophageal varices and bleeding risk in cirrhotic patients in Child-Pugh classes A and B

Purpose

To evaluate if the hepatic arterial perfusion index (HPI) in liver parenchyma of cirrhotic patients can serve as a surrogate parameter for stratifying the degree of esophageal varices and related bleeding risks.

Methods

CT image data of sixty-six patients (59 men; mean age 68 years ± 10 years) with liver cirrhosis (Child–Pugh class A (35/66, 53%), B (25/66, 38%), and C (6/66, 9%) who underwent perfusion CT (PCT) for hepatocellular carcinoma (HCC) screening between April 2010 and January 2019 were retrospectively identified. HPI, a parameter calculated by a commercially available CT liver perfusion analysis software that is based on the double maximum slope model, using time attenuation curve to determine perfusion, was correlated with the degree of esophageal varices diagnosed at endoscopy and the number of bleeding events.

Results

Eta correlation coefficient for HPI/presence of esophageal varices was very weak (0.083). Spearman-Rho for HPI/grading of esophageal varices was very weak (0.037 (p = 0.804)). Kendall-Tau-b for HPI/grading of esophageal varices was very weak (0.027 (p = 0.807)). ANOVA and Bonferroni post-hoc-tests showed no significant difference of HPI between different grades of esophageal varices (F (3, 62) = 1.676, p = 0.186). Eta correlation coefficient for HPI/bleeding event was very weak (0.126).

Conclusion

The stratification of the degree of esophageal varices and the related bleeding risk by correlation with the HPI as a surrogate parameter for portal venous hypertension was not possible for patients with liver cirrhosis in Child–Pugh class A and B.

Graphic abstract

Applying arterial enhancement fraction (AEF) texture features to predict the tumor response in hepatocellular carcinoma (HCC) treated with Transarterial chemoembolization (TACE)

Background

To evaluate the application of Arterial Enhancement Fraction (AEF) texture features in predicting the tumor response in Hepatocellular Carcinoma (HCC) treated with Transarterial Chemoembolization (TACE) by means of texture analysis.

Methods

HCC patients treated with TACE in Shengjing Hospital of China Medical University from June 2018 to December 2019 were retrospectively enrolled in this study. Pre-TACE Contrast Enhanced Computed Tomography (CECT) and imaging follow-up within 6 months were both acquired. The tumor responses were categorized according to the modified RECIST (mRECIST) criteria. Based on the CECT images, Region of Interest (ROI) of HCC lesion was drawn, the AEF calculation and texture analysis upon AEF values in the ROI were performed using CT-Kinetics (C.K., GE Healthcare, China). A total of 32 AEF texture features were extracted and compared between different tumor response groups. Multi-variate logistic regression was performed using certain AEF features to build the differential models to predict the tumor response. The Receiver Operator Characteristic (ROC) analysis was implemented to assess the discriminative performance of these models.

Results

Forty-five patients were finally enrolled in the study. Eight AEF texture features showed significant distinction between Improved and Un-improved patients (p < 0.05). In multi-variate logistic regression, 9 AEF texture features were applied into modeling to predict “Improved” outcome, and 4 AEF texture features were applied into modeling to predict “Un-worsened” outcome. The Area Under Curve (AUC), diagnostic accuracy, sensitivity, and specificity of the two models were 0.941, 0.911, 1.000, 0.826, and 0.824, 0.711, 0.581, 1.000, respectively.

Conclusions

Certain AEF heterogeneous features of HCC could possibly be utilized to predict the tumor response to TACE treatment.

Advanced CT techniques for assessing hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth-most common cancer in the world, and hepatic dynamic CT studies are routinely performed for its evaluation. Ongoing studies are examining advanced imaging techniques that may yield better findings than are obtained with conventional hepatic dynamic CT scanning. Dual-energy CT-, perfusion CT-, and artificial intelligence-based methods can be used for the precise characterization of liver tumors, the quantification of treatment responses, and for predicting the overall survival rate of patients. In this review, the advantages and disadvantages of conventional hepatic dynamic CT imaging are reviewed and the general principles of dual-energy- and perfusion CT, and the clinical applications and limitations of these technologies are discussed with respect to HCC. Finally, we address the utility of artificial intelligence-based methods for diagnosing HCC.

Fusion of Preinterventional MR Imaging With Liver Perfusion CT After RFA of Hepatocellular Carcinoma: Early Quantitative Prediction of Local Recurrence

OBJECTIVES

The aim of this study was to evaluate the ability of fusion of pretreatment magnetic resonance (MR) imaging with posttreatment perfusion-CT (P-CT) after radiofrequency ablation (RFA) of hepatocellular carcinomas (HCCs) and to determine treatment success in an objective, quantitative way.

MATERIALS AND METHODS

In this institutional review board-approved study, 39 patients (78.4% male; mean age 68.2 ± 8.5 years) with a total of 43 HCCs, who underwent RFA at our institution and had diagnostic pre-RFA MR imaging and post-RFA P-CT, were included in the study. Post-RFA P-CT was performed within 24 hours after RFA. In a first step, the pre-RFA MR imaging, depicting the HCC, was registered onto the post-RFA P-CT using nonrigid image registration. After image registration, the MR data were reloaded jointly with the calculated perfusion parameter volumes into the perfusion application for quantitative analysis. A 3-dimensional volume of interest was drawn around the HCC and the ablation zone; both outlines were automatically projected onto all perfusion maps. Resulting perfusion values (normalized peak enhancement [NPE, %]; arterial liver perfusion [ALP, in mL/min/100 mL]; BF [blood flow, mL/100 mL/min]; and blood volume [BV, mL/100 mL]) and histogram data were recorded. Local tumor recurrence was defined in follow-up imaging according to the EASL guidelines.

RESULTS

Image registration of MR imaging and CT data was successful in 37 patients (94.9%). Local tumor recurrence was observed in 5 HCCs (12%). In the local tumor recurrence group (LTR-group), HCC size was significantly larger (22.7 ± 3.9 cm vs 17.8 ± 5.3 cm, P = 0.035) and the ablation zone was significantly smaller (29.8 ± 6.9 cm vs 39.3 ± 6.8 cm, P = 0.014) compared with the no-local tumor recurrence group (no-LTR group). The differences (ablation zone - tumor) of the perfusion parameters NPE, ALP, BF, and BV significantly differed between the 2 groups (all P's < 0.005). Especially, the difference (ablation zone - tumor) of NPE and ALP, with a cutoff value of zero, accurately differentiated between LTR or no-LTR in all cases. A negative difference of these perfusion parameters identified local tumor recurrence in all cases.

CONCLUSIONS

Image registration of pre-RFA MR imaging onto post-RFA P-CT is feasible and allows to predict local tumor recurrence within 24 hours after RFA in an objective, quantitative manner and with excellent accuracy.

Usefulness of Cone-Beam CT-Based Liver Perfusion Mapping for Evaluating the Response of Hepatocellular Carcinoma to Conventional Transarterial Chemoembolization

We investigated the cone beam computed tomography (CBCT)-based-liver-perfusion-mapping usefulness during transarterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) to access treatment response and predict outcomes. From October 2016 to September 2018, 42 patients with HCCs scheduled for conventional TACE were prospectively enrolled. Three reviewers evaluated the unenhanced and contrast-enhanced CBCT and CBCT-based-liver-perfusion-mapping of each tumor. Parenchymal blood volume (PBV) was measured. The operator’s judgment on the technical results was recorded. Response outcome was determined on follow-up CT or magnetic resonance imaging, according to the modified Response Evaluation Criteria in Solid Tumors. Diagnostic performance for detection of a viable tumor was evaluated using multiple logistic regression with C-statistics. CBCT-based-liver-perfusion-mapping and the maximum PBV of the tumor were significant in multiple logistic regression analysis of response (p < 0.0001, p = 0.0448, respectively), with C-statistics of 0.9540 and 0.7484, respectively. Diagnostic accuracy of operator’s judgment was 79.66% (95%CI 69.39%–89.93%). Diagnostic performance of CBCT-based-liver-perfusion-mapping showed a high concordance in three reviewers. The mean PBV of tumor, maximum PBV of tumor, and mean PBV of liver significantly decreased after TACE (each p < 0.001). In ROC curve analysis, the AUC for prediction of residual tumor by the maximum PBV of tumor after TACE was 0.7523, with 80.8% sensitivity and 60.6% specificity.

Comparative analysis of three-dimensional volume rendering and maximum intensity projection for preoperative planning in liver cancer

Three-dimensional imaging is a useful tool to evaluate liver structure and surrounding vessels for preoperative planning. In this study, we compared two methods of visualizing vascular maps on computed tomography including maximum intensity projection (MIP) and 3D volume rendered (VR) imaging. We compiled important imaging components of pre-surgical planning, and developed criteria for comparison. The imaging techniques were compared based on colorization, volume quantification, rotation, vessel delineation, small vessel clarity, and segmental liver isolation. MIP had more overall limitations due to reduced differentiation of superimposed structures, motion artifact, and interference from calcifications. We determined that because 3D quantitative volume rendered imaging can provide more detail and perspective than MIP imaging, it may be more useful in preoperative planning for patients with liver malignancy. Advanced 3D imaging is a useful tool that can have profound clinical implications on cancer detection and surgical planning.

CT liver perfusion in patients with hepatocellular carcinoma: can we modify acquisition protocol to reduce patient exposure?

OBJECTIVES

To investigate the potential of decreasing the number of scans and associated radiation exposure involved in CT liver perfusion (CTLP) dynamic studies for hepatocellular carcinoma (HCC) assessment.

METHODS

Twenty-four CTLP image datasets of patients with HCC were retrospectively analyzed. All examinations were performed on a modern CT system using a standard acquisition protocol involving 35 scans with 1.7 s interval. A deconvolution-based or a standard algorithm was employed to compute ten perfusion parametric maps. 3D ROIs were positioned on 33 confirmed HCCs and non-malignant parenchyma. Analysis was repeated for two subsampled datasets generated from the original dataset by including only the (a) 18 odd-numbered scans with 3.4 s interval and (b) 18 first scans with 1.7 s interval. Standard and modified datasets were compared regarding the (a) accuracy of calculated perfusion parameters, (b) power of parametric maps to discriminate HCCs from liver parenchyma, and (c) associated radiation exposure.

RESULTS

When the time interval between successive scans was doubled, perfusion parameters of HCCs were found unaffected (p > 0.05) and the discriminating efficiency of parametric maps was preserved (p < 0.05). In contrast, significant differences were found for all perfusion parameters of HCCs when acquisition duration was reduced to half (p < 0.05), while the discriminating efficiency of four parametric maps was significantly deteriorated (p < 0.05). Modified CTLP acquisition protocols were found to involve 48.5% less patient exposure.

CONCLUSIONS

Doubling the interscan time interval may considerably reduce radiation exposure from CTLP studies performed for HCC evaluation without affecting the diagnostic efficiency of perfusion maps generated with either standard or deconvolution-based mathematical model.

KEY POINTS

• CT liver perfusion for HCC diagnosis/assessment is not routinely used in clinical practice mainly due to the associated high radiation exposure. • Two alternative acquisition protocols involving 18 scans of the liver were compared with the standard 35-scan protocol. • Increasing the time interval between successive scans to 3.4 s was found to preserve the accuracy of computed perfusion parameters derived with a standard or a deconvolution-based model and to reduce radiation exposure by 48.5%.

Feasibility of wide detector three-pass arterial phase liver CT in patients with cirrhosis: timing of hyperenhancing lesion peak conspicuity

PURPOSE

To evaluate feasibility of a wide detector liver CT protocol with three acquisitions in the hepatic arterial phase.

METHODS

Forty-one patients with cirrhosis prospectively underwent a wide detector axial liver CT protocol. Three 16 cm axial liver acquisitions were obtained during a single breath hold at peak aortic enhancement plus 10, 20, and 25 s. Two readers working separately scored overall exam quality, identified hyperenhancing lesions, and subjectively scored and ranked relative lesion conspicuity. Objective lesion enhancement was measured and CNR calculated. Data were analyzed using a generalized linear models and Tukey's post hoc testing.

RESULTS

Seventy-one hyperenhancing lesions were identified with average size of 1.8 cm (range 0.4-9.6 cm). The two readers separately identified 60 and 54 lesions on the 10 s arterial acquisition, 70 and 67 on the 20 s, and 52 and 51 on the 25 s. The readers determined all exams had diagnostic image quality. Subjective ranking of lesion conspicuity was greatest at 20 s in 62% of lesions but was greatest at 10 or 25 s in 38%. CNR was highest at 20 s in 58% of lesions but was highest at 10 or 25 s in 42%. Overall, there was no significant difference in mean CNR between the three arterial acquisitions.

CONCLUSION

A wide detector axial liver CT protocol with three acquisitions in the hepatic arterial phase is technologically feasible and results in diagnostic image quality. With this protocol, peak subjective and objective hyperenhancing lesion conspicuity may be earlier or later than 20 s in up to 40% of lesions.

Dynamic CT angiography for therapy evaluation after transarterial chemoembolization of hepatocellular carcinoma

Background

Liver dynamic computed tomography (CT) is an established method for pre- and post-interventional evaluation of hepatocellular carcinoma. To date only the liver parenchyma and perfusion information of dynamic CT has been evaluated widely.

Purpose

To evaluate the vascular information contained in dynamic CT datasets.

Material and Methods

Dynamic CT performed one day after transarterial chemoembolization (60 mL of contrast medium, 6 mL/s, 40 s scan duration) were retrospectively evaluated. Conventional slice and angiographic maximum-intensity-projection reconstructions were calculated on a multi-modality post-processing platform. Datasets were evaluated for viable tumor, anatomy of the vasculature, and potential tumor-feeding vessels. The results were compared to digital subtraction angiography images.

Results

In total, 94 treated hepatocellular carcinoma nodules were evaluated (62 dynamic CT scans, 46 patients [34 men; mean age = 69 years]). Forty-six partially viable tumors were diagnosed after transarterial chemoembolization. In all of these, tumor-feeding vessels were found in dynamic CT. Seventeen suspected extra-hepatic tumor feeders were reported, of which 14 had not been found during previous transarterial chemoembolization.

Conclusion

Dynamic CT is useful in post-interventional imaging of hepatocellular carcinoma after transarterial chemoembolization due to its ability to detect residual viable tumor parts and to show previously unknown intra- and extra-hepatic tumor-feeding vessels.

Advances in the early diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers globally. In contrast to the declining death rates observed for all other common cancers such as breast, lung, and prostate cancers, the death rates for HCC continue to increase by ~2–3% per year because HCC is frequently diagnosed late and there is no curative therapy for an advanced HCC. The early diagnosis of HCC is truly a big challenge. Over the past years, the early diagnosis of HCC has relied on surveillance with ultrasonography (US) and serological assessments of alpha-fetoprotein (AFP). However, the specificity and sensitivity of US/AFP is not satisfactory enough to detect early onset HCC. Recent technological advancements offer hope for early HCC diagnosis. Herein, we review the progress made in HCC diagnostics, with a focus on emerging imaging techniques and biomarkers for early disease diagnosis.

Dynamic Computed Tomography Perfusion Imaging: Complementary Diagnostic Tool in Hepatocellular Carcinoma Assessment From Diagnosis to Treatment Follow-up

Early diagnosis of HCC is of paramount importance in order to enable the application of curative treatments. Among these, radiofrequency ablation (RFA) is actually considered the most effective ablative therapy for early stage hepatocellular carcinoma (HCC) not suitable for surgery. On the other hand, transarterial chemoembolization (TACE) represents the standard of care for intermediate stage HCC and compensated liver function. Finally, sorafenib, an oral antiangiogenic targeted drug, is the only approved systemic therapy for advanced HCC with vascular invasion, extrahepatic spread, and well-preserved liver function. Beside traditional radiological techniques, new functional imaging tools have been introduced in order to provide not only morphological information but also quantitative functional data. In this review, we analyze perfusion-CT (pCT) from a technical point of view, describing the main different mathematical analytical models for the quantification of tissue perfusion from acquired CT raw data, the most commonly acquired perfusion parameters, and the technical parameters required to perform a standard pCT examination. Moreover, a systematic review of the literature was performed to assess the role of pCT as an emerging imaging biomarker for HCC diagnosis, response evaluation to RFA, TACE, and sorafenib, and we examine its challenges in HCC management.

Liver CT perfusion: which is the relevant delay that reduces radiation dose and maintains diagnostic accuracy?

OBJECTIVES

High radiation dose during CT perfusion (CTp) studies contributes to prevent CTp application in daily clinical practice. This work evaluates the consequences of scan delay on perfusion parameters and provides guidelines to help reducing the radiation dose by choosing the most appropriate delay.

METHODS

Fifty-nine patients (34 men, 25 women; mean age 68 ± 12) with colorectal cancer, without underlying liver disease, underwent liver CTp, with the acquisition starting simultaneously with iodinated contrast agent injection. Blood flow (BF) and hepatic perfusion index (HPI) were computed on the acquired examinations and compared with those of the same examinations when a variable scan delay (τ) is introduced. Dose length product, CT dose index, and effective dose were also computed on original and delayed examinations.

RESULTS

Altogether, three groups of delays (τ ≤ 4 s, 5 s ≤ τ ≤ 9 s, τ ≥ 10 s) were identified, yielding increasing radiation dose saving (RDS) (RDS ≤ 9.5%, 11.9% ≤ RDS ≤ 21.4%, RDS ≥ 23.8%) and decreasing perfusion accuracy (high (τ ≤ 4 s), medium (5 s ≤ τ ≤ 9 s), low (τ ≥ 10 s)). In particular, single-input and arterial BF and HPI were more insensitive to delay as regards the absolute variations (only 1 ml/min/100 g and 1%, respectively, for τ ≤ 9 s), than portal and total BF.

CONCLUSION

Using delays lower than 4 s does not change perfusion accuracy and conveys unnecessary dose to patients. Conversely, starting the acquisition 9 s after contrast agent injection yields a RDS of about 21%, with no significant losses in perfusion accuracy.

KEY POINTS

• Scan delays lower than 4 s do not alter perfusion accuracy and deliver an unnecessary radiation dose to patients. • Radiation dose delivered to patients can be reduced by 21.4% by introducing a 9-s scan delay, while keeping accurate perfusion values. • Using scan delays higher than 10 s, some perfusion parameters (portal and total BF) were inaccurate.

Perfusion-CT analysis for assessment of hepatocellular carcinoma lesions: diagnostic value of different perfusion maps

BACKGROUND

Computed tomography liver perfusion (CTLP) has been improved in recent years, offering a variety of perfusion-parametric maps. A map that better discriminates hepatocellular carcinoma (HCC) is still to be found.

PURPOSE

To compare different CTLP maps, regarding their ability to differentiate cirrhotic or non-cirrhotic parenchyma from malignant HCC.

MATERIAL AND METHODS

Twenty-six patients (11 cirrhotic) with 50 diagnosed HCC lesions, underwent CTLP on a 128-row dual-energy CT system. Nine different maps were generated. Regions of interest (ROIs) were positioned on non-tumorous parenchyma and on HCCs found on previous magnetic resonance imaging. Perfusion parameters for non-cirrhotic and cirrhotic livers were compared. Receiver operating characteristic (ROC) analysis was employed to evaluate each map's ability to discriminate HCCs from non-tumorous livers. Comparison of ROC curves was performed to evaluate statistical significance of differences in the discriminating efficiency of derived perfusion maps.

RESULTS

Perfusion parameters for non-tumorous liver and HCCs recorded in cirrhotic patients did not significantly differ from corresponding values recorded in non-cirrhotic patients ( P > 0.05). The highest power for HCC discrimination was found for the maximum-slope-of-increase (MSI) parametric map, with estimated the area under ROC curve of 0.997. An MSI cut-off criterion of 2.2 HU/s was found to provide 96% sensitivity and 100% specificity. Time to peak, blood flow, and transit time to peak were also found to have high discriminating power.

CONCLUSION

Among available CTLP-derived perfusion parameters, MSI was found to provide the highest diagnostic accuracy in discriminating HCCs from non-tumorous parenchyma. Perfusion parameters for non-tumorous livers and HCCs were not found to significantly differ between cirrhotic and non-cirrhotic patients.

Hepatocellular Carcinoma: State of the Art Imaging and Recent Advances

The incidence of hepatocellular carcinoma (HCC) is increasing, with this trend expected to continue to the year 2030. Hepatocarcinogenesis follows a predictable course, which makes adequate identification and surveillance of at-risk individuals central to a successful outcome. Moreover, imaging is central to this surveillance, and ultimately to diagnosis and management. Many liver study groups throughout Asia, North America and Europe advocate a surveillance program for at-risk individuals to allow early identification of HCC. Ultrasound is the most commonly utilized imaging modality. Many societies offer guidelines on how to diagnose HCC. The Liver Image Reporting and Data System (LIRADS) was introduced to standardize the acquisition, interpretation, reporting and data collection of HCC cases. The LIRADS advocates diagnosis using multiphase computed tomography or magnetic resonance imaging (MRI) imaging. The 2017 version also introduces contrast-enhanced ultrasound as a novel approach to diagnosis. Indeed, imaging techniques have evolved to improve diagnostic accuracy and characterization of HCC lesions. Newer techniques, such as T1 mapping, intravoxel incoherent motion analysis and textural analysis, assess specific characteristics that may help grade the tumor and guide management, allowing for a more personalized approach to patient care. This review aims to analyze the utility of imaging in the surveillance and diagnosis of HCC and to assess novel techniques which may increase the accuracy of imaging and determine optimal treatment strategies.

Comparison of patient dose from routine multi-phase and dynamic liver perfusion CT studies taking into account the effect of iodinated contrast administration

OBJECTIVES

To accurately determine and compare patient radiation burden from routine multi-phase CT (MPCT) and dynamic CT liver perfusion (CTLP) studies taking into account the effect of iodine uptake of exposed tissues/organs.

MATERIALS AND METHODS

40 consecutive MPCT of upper abdomen and 40 consecutive CTLP studies performed on a modern CT scanner were retrospectively studied. Iodine uptake of radiosensitive tissues at the time of acquisition was calculated through the difference of tissues' CT numbers between NECT and CECT images. Monte Carlo simulation and mathematical anthropomorphic phantoms were employed to derive patient-size-specific organ dose data from each scan involved taking into account the effect of iodinated contrast uptake on absorbed dose. Effective dose estimates were derived for routine multiphase CT and CTLP by summing up the contribution of NECT and CECT scans involved.

RESULTS

The mean underestimation error in organ doses from CECT exposures if iodine uptake is not encountered was found to be 2.2%-38.9%. The effective dose to an average-size patient from routine 3-phase CT, 4-phase CT and CTLP studies was found to be 20.6, 27.7 and 25.8 mSv, respectively. Effective dose from CTLP was found lower than 4-phase CT of upper abdomen irrespective of patient body size. Compared to 3-phase CT, the radiation burden from CTLP was found to be higher for average size-patients but again lower for overweight patients.

CONCLUSIONS

Modern CT technology allows CTLP studies at comparable or even lower patient radiation burden compared to routine multi-phase liver CT imaging.

Recent advances in non-invasive magnetic resonance imaging assessment of hepatocellular carcinoma

Magnetic resonance (MR) imaging of the liver is an important tool for the detection and characterization of focal liver lesions and for assessment of diffuse liver disease, having several intrinsic characteristics, represented by high soft tissue contrast, avoidance of ionizing radiation or iodinated contrast media, and more recently, by application of several functional imaging techniques (i.e., diffusion-weighted sequences, hepatobiliary contrast agents, perfusion imaging, magnetic resonance (MR)-elastography, and radiomics analysis). MR functional imaging techniques are extensively used both in routine practice and in the field of clinical and pre-clinical research because, through a qualitative rather than quantitative approach, they can offer valuable information about tumor tissue and tissue architecture, cellular biomarkers related to the hepatocellular functions, or tissue vascularization profiles related to tumor and tissue biology. This kind of approach offers in vivo physiological parameters, capable of evaluating physiological and pathological modifications of tissues, by the analysis of quantitative data that could be used in tumor detection, characterization, treatment selection, and follow-up, in addition to those obtained from standard morphological imaging. In this review we provide an overview of recent advanced techniques in MR for the diagnosis and staging of hepatocellular carcinoma, and their role in the assessment of response treatment evaluation.

Noninvasive imaging of hepatocellular carcinoma: From diagnosis to prognosis

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and a major public health problem worldwide. Hepatocarcinogenesis is a complex multistep process at molecular, cellular, and histologic levels with key alterations that can be revealed by noninvasive imaging modalities. Therefore, imaging techniques play pivotal roles in the detection, characterization, staging, surveillance, and prognosis evaluation of HCC. Currently, ultrasound is the first-line imaging modality for screening and surveillance purposes. While based on conclusive enhancement patterns comprising arterial phase hyperenhancement and portal venous and/or delayed phase wash-out, contrast enhanced dynamic computed tomography and magnetic resonance imaging (MRI) are the diagnostic tools for HCC without requirements for histopathologic confirmation. Functional MRI techniques, including diffusion-weighted imaging, MRI with hepatobiliary contrast agents, perfusion imaging, and magnetic resonance elastography, show promise in providing further important information regarding tumor biological behaviors. In addition, evaluation of tumor imaging characteristics, including nodule size, margin, number, vascular invasion, and growth patterns, allows preoperative prediction of tumor microvascular invasion and patient prognosis. Therefore, the aim of this article is to review the current state-of-the-art and recent advances in the comprehensive noninvasive imaging evaluation of HCC. We also provide the basic key concepts of HCC development and an overview of the current practice guidelines.

Imaging performance and clinical value of contrast-enhanced ultrasonography and computed tomography in the diagnosis of liver cancer

The imaging performance and clinical value of contrast-enhanced ultrasonography (CEUS) combined with CT in diagnosis of liver cancer were investigated. A total of 426 liver cancer patients treated in Yuhuangding Hospital (Yantai, China) from February 2011 to May 2016 were selected. Among them, 222 patients underwent CEUS examination, 204 patients underwent CT examination, and 102 patients underwent CEUS combined with CT examination. Sensitivity and specificity of the three methods were examined. CT showed a low density in 92.6% of patients (189 patients) and a high-low hybrid density in 6.4% (13 patients), with calcification seen in 2.5% of patients (5 patients) and bleeding in 3.4% (7 patients). Lesions: 76.5% (156 cases) of patients with multiple type, 23.5% (48 cases) with single type. CEUS showed overall enhancement in 53.2% patients (118 cases), heterogenous enhancement in 16.7% (37 cases), peripheral enhancement in 18.9% of patients (42 cases), necrosis of liquefaction in 11.3% (25 cases). In 65.3% (145 cases) of patients, the portal venous phase and the delayed phase showed a low enhancement, while 34.7% (77 cases) showed no enhancement. The sensitivity and specificity rates of CEUS combined with CT detection of liver cancer were 87.8, 88.2 and 94.1%, respectively. The ROC curve analysis showed that the sensitivity and specificity of CEUS in the diagnosis of liver cancer were 76.8 and 78.9%, respectively. The sensitivity and specificity of CT were 81.2 and 85.5%, respectively. The sensitivity and specificity of CEUS combined with CT were 90.4 and 92.7%, respectively. CEUS combined with CT detection can make-up for the deficiencies of each other and effectively improve the coincidence rate of liver cancer diagnosis, which can be used as an effective examination method for the diagnosis of liver cancer.

Dynamic Measurement of Arterial Liver Perfusion With an Interventional C-Arm System

PURPOSE

Objective intraprocedural measurement of hepatic blood flow could provide a quantitative treatment end point for locoregional liver procedures. This study aims to validate the accuracy and reproducibility of cone-beam computed tomography perfusion (CBCTp) measurements of arterial liver perfusion (ALP) against clinically available computed tomography perfusion (CTp) measurements in a swine embolization model.

METHODS

Triplicate CBCTp measurements using a selective arterial contrast injection were performed before and after complete embolization of the left lobe of the liver in 5 swine. Two CBCTp protocols were evaluated that differed in sweep duration (3.3 vs 4.5 seconds) and the number of acquired projection images (166 vs 248). The mean ALP was measured within identical volumes of interest selected in the embolized and nonembolized regions of the perfusion map generated from each scan. Postembolization CBCTp values were also compared with CTp measurements.

RESULTS

The 2 CBCTp protocols demonstrated high concordance correlation (0.90, P < 0.001). Both CBCTp protocols showed higher reproducibility than CTp in the nontarget lobe, with an intraclass correlation of 0.90 or greater for CBCTp and 0.83 for CTp (P < 0.001 for all correlations). The ALP in the embolized lobe was nearly zero and hence excluded for reproducibility. High concordance correlation was observed between the CTp and each CBCTp protocol, with the shorter CBCTp protocol reaching a concordance correlation of 0.75 and the longer achieving 0.87 (P < 0.001 for both correlations).

CONCLUSIONS

Dynamic blood flow measurement using an angiographic C-arm system is feasible and produces quantitative results comparable to CTp.

Dual-energy CT: a phantom comparison of different platforms for abdominal imaging

OBJECTIVES

Evaluation of imaging performance across dual-energy CT (DECT) platforms, including dual-layer CT (DLCT), rapid-kVp-switching CT (KVSCT) and dual-source CT (DSCT).

METHODS

A semi-anthropomorphic abdomen phantom was imaged on these DECT systems. Scans were repeated three times for CTDIvol levels of 10 mGy, 20 mGy, 30 mGy and different fat-simulating extension rings. Over the available range of virtual-monoenergetic images (VMI), noise as well as quantitative accuracy of hounsfield units (HU) and iodine concentrations were evaluated.

RESULTS

For all VMI levels, HU values could be determined with high accuracy compared to theoretical values. For KVSCT and DSCT, a noise increase was observed towards lower VMI levels. A patient-size dependent increase in the uncertainty of quantitative iodine concentrations is observed for all platforms. For a medium patient size the iodine concentration root-mean-square deviation at 20 mGy is 0.17 mg/ml (DLCT), 0.30 mg/ml (KVSCT) and 0.77mg/ml (DSCT).

CONCLUSION

Noticeable performance differences are observed between investigated DECT systems. Iodine concentrations and VMI HUs are accurately determined across all DECT systems. KVSCT and DLCT deliver slightly more accurate iodine concentration values than DSCT for investigated scenarios. In DLCT, low-noise and high-image contrast at low VMI levels may help to increase diagnostic information in abdominal CT.

KEY POINTS

• Current dual-energy CT platforms provide accurate, reliable quantitative information. • Dual-energy CT cross-platform evaluation revealed noticeable performance differences between different systems. • Dual-layer CT offers constant noise levels over the complete energy range.

Evaluation of splenic perfusion and spleen size using dynamic computed tomography: Usefulness in assessing degree of liver fibrosis

AIM

To enhance the usefulness of splenic perfusion evaluated by means of dynamic computed tomography (CT) and spleen size in assessing the degree of liver fibrosis.

METHODS

We retrospectively studied 133 patients who had undergone dynamic CT before hepatectomy. Fibrosis was histologically established in all. First we calculated splenic perfusion parameters K₁ (inflow rate constant), 1/k₂ (mean transit time; MTT), and K₁ /k₂ (distribution volume; V_d ), using compartment model analysis. Then we compared the stage of fibrosis with splenic perfusion and spleen size (long axis, R), using the Kruskal-Wallis test and multiple comparisons. After that, we assessed the diagnostic accuracy of the combination of splenic perfusion, spleen size, age, gender, and the presence or absence of hepatitis B and hepatitis C viral infection in detecting liver fibrosis, using stepwise regression and receiver operating characteristic analysis.

RESULTS

Significant differences (P < 0.05) in MTT were observed in comparisons between fibrosis stages F0 and F4, between F1 and F4, and between F2 and F4. Significant differences (P < 0.05) in R were observed in comparisons between F0 and F4, and between F1 and F4. Considering the presence or absence of hepatitis B and C viral infection along with MTT and R, the areas under the receiver operating characteristic curves were 0.89 for ≥F1, 0.83 for ≥F2, 0.82 for ≥F3, and 0.82 for F4.

CONCLUSION

Splenic MTT and spleen size are helpful in assessing liver fibrosis.

Multi-detector CT: Liver protocol and recent developments

Multi-detector computed tomography is today the workhorse in the evaluation of the vast majority of patients with known or suspected liver disease. Reasons for that include widespread availability, robustness and repeatability of the technique, time-efficient image acquisitions of large body volumes, high temporal and spatial resolution as well as multiple post-processing capabilities. However, as the technique employs ionizing radiation and intravenous iodine-based contrast media, the associated potential risks have to be taken into account. In this review article, liver protocols in clinical practice are discussed with emphasis on optimisation strategies. Furthermore, recent developments such as perfusion CT and dual-energy CT and their applications are presented.

Computed tomography perfusion imaging for monitoring transarterial chemoembolization of hepatocellular carcinoma

PURPOSE

To prospectively monitor changes in tumor perfusion of hepatocellular carcinoma (HCC) in response to doxorubicin-eluted bead based transarterial chemoembolization (DEB-TACE) using perfusion-CT (P-CT).

METHODS AND MATERIALS

24 patients (54-79 years) undergoing P-CT before and shortly after DEB-TACE of HCC were prospectively included in this dual-center study. Two readers determined arterial-liver-perfusion (ALP, mL/min/100mL), portal-venous-perfusion (PLP, mL/min/100mL) and the hepatic-perfusion-index (HPI, %) by placing matched regions-of-interests within each HCC before and after DEB-TACE. Imaging follow-up was used to determine treatment response and to distinguish complete from incomplete responders. Performance of P-CT for prediction and early response assessment was determined using receiver-operating-characteristics curve analysis.

RESULTS

Interreader agreement was fair to excellent (ICC, 0.716-0.942). PLP before DEB-TACE was significantly higher in pre-treated vs non-treated lesions (P<0.05). Mean changes of ALP, PLP and HPI from before to after DEB-TACE were -55%, +24% and -27%. ALP and HPI after DEB-TACE were correlating with response-grades (r=0.45/0.48; both, p<0.04), showing an area-under-the-curve (AUC) of 0.74 and 0.80 respectively for identification of complete response.

CONCLUSION

High arterial and low portal-venous perfusion of HCC early after DEB-TACE indicates incomplete response with good diagnostic accuracy.

Early perfusion changes within 1 week of systemic treatment measured by dynamic contrast-enhanced MRI may predict survival in patients with advanced hepatocellular carcinoma

OBJECTIVES

To correlate early changes in the parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) within 1 week of systemic therapy with overall survival (OS) in patients with advanced hepatocellular carcinoma (HCC).

METHODS

Eighty-nine patients with advanced HCC underwent DCE-MRI before and within 1 week following systemic therapy. The relative changes of six DCE-MRI parameters (Peak, Slope, AUC, Ktrans, Kep and Ve) of the tumours were correlated with OS using the Kaplan-Meier model and the double-sided log-rank test.

RESULTS

All patients died and the median survival was 174 days. Among the six DCE-MRI parameters, reductions in Peak, AUC, and Ktrans, were significantly correlated with one another. In addition, patients with a high Peak reduction following treatment had longer OS (P = 0.023) compared with those with a low Peak reduction. In multivariate analysis, a high Peak reduction was an independent favourable prognostic factor in all patients [hazard ratio (HR), 0.622; P = 0.038] after controlling for age, sex, treatment methods, tumour size and stage, and Eastern Cooperative Oncology Group performance status.

CONCLUSIONS

Early perfusion changes within 1 week following systemic therapy measured by DCE-MRI may aid in the prediction of the clinical outcome in patients with advanced HCC.

KEY POINTS

• DCE-MRI is helpful to evaluate perfusion changes of HCC after systemic treatment. • Early perfusion changes within 1 week after treatment may predict overall survival. • High Peak reduction was an independent favourable prognostic factor after systemic treatment.

Detection and differentiation of early hepatocellular carcinoma from cirrhosis using CT perfusion in a rat liver model

BACKGROUND

Functional imaging such as CT perfusion can detect morphological and hemodynamic changes in hepatocellular carcinoma (HCC). Pre-carcinoma and early HCC nodules are difficult to differentiate by observing only their hemodynamics changes. The present study aimed to investigate hemodynamic parameters and evaluate their differential diagnostic cut-off between pre-carcinoma and early HCC nodules using CT perfusion and receiver operating characteristic (ROC) curves.

METHODS

Male Wistar rats were randomly divided into control (n=20) and experimental (n=70) groups. Diethylnitrosamine (DEN) was used to induce pre-carcinoma and early HCC nodules in the experimental group. Perfusion scanning was carried out on all survival rats discontinuously from 8 to 16 weeks. Hepatic portal perfusion (HPP), hepatic arterial fraction (HAF), hepatic arterial perfusion (HAP), hepatic blood volume (HBV), hepatic blood flow (HBF), mean transit time (MTT) and permeability of capillary vessel surface (PS) data were provided by mathematical deconvolution model. The perfusion parameters were compared among the three groups of rats (control, pre-carcinoma and early HCC groups) using the Kruskal-Wallis test and analyzed with ROC curves. Histological examination of the liver tissues with hematoxylin and eosin staining was performed after CT scan.

RESULTS

For HPP, HAF, HBV, HBF and MTT, there were significant differences among the three groups (P<0.05). HAF had the highest areas under the ROC curves: 0.80 (control vs pre-carcinoma groups) and 0.95 (control vs early HCC groups) with corresponding optimal cut-offs of 0.37 and 0.42, respectively. The areas under the ROC curves for HPP was 0.79 (control vs pre-carcinoma groups) and 0.92 (control vs early HCC groups) with corresponding optimal cut-offs of 136.60 mL/min/100 mg and 108.47 mL/min/100 mg, respectively.

CONCLUSIONS

CT perfusion combined with ROC curve analysis is a new diagnosis model for distinguishing between pre-carcinoma and early HCC nodules. HAF and HPP are the ideal reference indices.

CT Perfusion for Early Response Evaluation of Radiofrequency Ablation of Focal Liver Lesions: First Experience

PURPOSE

To investigate the value of perfusion CT (P-CT) for early assessment of treatment response in patients undergoing radiofrequency ablation (RFA) of focal liver lesions.

METHODS AND MATERIALS

20 consecutive patients (14 men; mean age 64 ± 14) undergoing P-CT within 24 h after RFA of liver metastases (n = 10) or HCC (n = 10) were retrospectively included. Two readers determined arterial liver perfusion (ALP, mL/min/100 mL), portal liver perfusion (PLP, mL/min/100 mL), and hepatic perfusion index (HPI, %) in all post-RFA lesions by placing a volume of interest in the necrotic central (CZ), the transition (TZ), and the surrounding parenchymal (PZ) zone. Patients were classified into complete responders (no residual tumor) and incomplete responders (residual/progressive tumor) using imaging follow-up with contrast-enhanced CT or MRI after a mean of 57 ± 30 days. Prediction of treatment response was evaluated using the area under the curve (AUC) from receiver operating characteristic analysis.

RESULTS

Mean ALP/PLP/HPI of both readers were 4.8/15.4/61.2 for the CZ, 9.9/16.8/66.3 for the TZ and 20.7/29.0/61.8 for the PZ. Interreader agreement of HPI was fair for the CZ (intraclass coefficient 0.713), good for the TZ (0.813), and excellent for the PZ (0.920). For both readers, there were significant differences in HPI of the CZ and TZ between responders and nonresponders (both, P < 0.05). HPI of the TZ showed the highest AUC (0.911) for prediction of residual tumor, suggesting a cut-off value of 76 %.

CONCLUSION

Increased HPI of the transition zone assessed with P-CT after RFA might serve as an early quantitative biomarker for residual tumor in patients with focal liver lesions.

Functional imaging in liver tumours

Functional imaging encompasses techniques capable of assessing physiological parameters of tissues, and offers useful clinical information in addition to that obtained from morphological imaging. Such techniques may include magnetic resonance imaging with diffusion-weighted sequences or hepatobiliary contrast agents, perfusion imaging, or molecular imaging with radiolabelled tracers. The liver is of major importance in oncological practice; not only is hepatocellular carcinoma one of the malignancies with steadily rising incidence worldwide, but hepatic metastases are regularly observed with a range of solid neoplasms. Within the realm of hepatic oncology, different functional imaging modalities may occupy pivotal roles in lesion characterisation, treatment selection and follow-up, depending on tumour size and type. In this review, we characterise the major forms of functional imaging, discuss their current application to the management of patients with common primary and secondary liver tumours, and anticipate future developments within this field.

The impact of clinically significant portal hypertension on the prognosis of patients with hepatocellular carcinoma after radiofrequency ablation: a propensity score matching analysis

OBJECTIVES

To assess the impact of clinically significant portal hypertension (CSPH) on the prognosis of patients with hepatocellular carcinoma (HCC) undergoing radiofrequency ablation (RFA).

METHODS

We retrospectively enrolled 280 treatment-naïve early-stage HCC patients who had Child-Pugh grade A or B and received upper gastrointestinal endoscopy at the time of HCC diagnosis. CSPH was defined as (1) a platelet count < 100,000/mm³ associated with splenomegaly and/or (2) the presence of oesophageal/gastric varices by endoscopy. Factors determining poor overall survival and recurrence after RFA were analysed by Cox proportional hazards model and propensity score matching analysis.

RESULTS

A total of 192 (68.6 %) patients had CSPH. The cumulative 5-year survival rates were 50.6 % and 76.7 % in patients with and without CSPH, respectively (p = 0.015). Based on multivariate analysis, age > 65 years (hazard ratio (HR) 1.740, p = 0.025), serum albumin levels ≤ 3.5 g/dL (HR 3.268, p < 0.001) and multiple tumours (HR 1.693, p = 0.046), but not CSPH, were independent risk factors associated with poor overall survival after RFA. Moreover, the overall survival rates were comparable between patients with and without CSPH after adjusting for confounding factors via propensity score matching analysis.

CONCLUSIONS

CSPH was not associated with poor outcomes after RFA.

KEY POINTS

• CSPH was common in HCC patients who underwent RFA therapy. • CSPH was not an independent risk factor in determining poor prognosis. • Serum albumin level was more important to determine the outcomes.

Arterio-portal shunts in the cirrhotic liver: perfusion computed tomography for distinction of arterialized pseudolesions from hepatocellular carcinoma

OBJECTIVES

To determine perfusion computed tomography (P-CT) findings for distinction of arterial pseudolesions (APL) from hepatocellular carcinoma (HCC) in the cirrhotic liver.

METHODS

32 APL and 21 HCC in 20 cirrhotic patients (15 men; 65 ± 10 years), who underwent P-CT for evaluation of HCC pre- (N = 9) or post- (N = 11) transarterial chemoembolization, were retrospectively included using CT follow-up as the standard of reference. All 53 lesions were qualitatively (visual) and quantitatively (perfusion parameters) analysed according to their shape (wedge, irregular, nodular), location (not-/adjunct to a fistula), arterial liver perfusion (ALP), portal venous liver perfusion (PLP), hepatic perfusion index (HPI). Accuracy for diagnosis of HCC was determined using receiver operating characteristics.

RESULTS

18/32 (56 %) APL were wedge shaped, 10/32 (31 %) irregular and 4/32 (12 %) nodular, while 11/21 (52 %) HCC were nodular or 10/21 (48 %) irregular, but never wedge shaped. Significant difference between APL and HCC was seen for lesion shape in pretreated lesions (P < 0.001), and for PLP and HPI in both pre- and post-treated lesions (all, P < 0.001). Diagnostic accuracy for HCC was best for combined assessment of lesion configuration and PLP showing an area under the curve of 0.901.

CONCLUSION

Combined assessment of lesion configuration and portal venous perfusion derived from P-CT allows best to discriminate APL from HCC with high diagnostic accuracy.

KEY POINTS

• Arterio-portal shunting is common in the cirrhotic liver, especially after local treatment. • Arterial pseudolesions (APL) due to shunting might mimic hepatocellular carcinoma (HCC). • Perfusion-CT allows for qualitative and quantitative assessment of liver lesions. • Lesion configuration fails to discriminate APL from HCC in locally treated patients. • Integration of quantitative perfusion analysis improves accuracy for diagnosis of HCC.

Comparison of organ-specific-radiation dose levels between 70 kVp perfusion CT and standard tri-phasic liver CT in patients with hepatocellular carcinoma using a Monte-Carlo-Simulation-based analysis platform

Purpose

The aim of this study was to systematically compare organ-specific-radiation dose levels between a radiation dose optimized perfusion CT (dVPCT) protocol of the liver and a tri-phasic standard CT protocol of the liver using a Monte-Carlo-Simulation-based analysis platform.

Methods and materials

The complete CT data of 52 patients (41 males; mean age 65 ± 12) with suspected HCC that underwent dVPCT examinations on a 3rd generation dual-source CT (Somatom Force, Siemens) with a dose optimized tube voltage of 70 kVp or 80 kVp were exported to an analysis platform (Radimetrics, Bayer). The dVPCT studies were matched with a reference group of 50 patients (35 males; mean age 65 ± 14) that underwent standard tri-phasic CT (sCT) examinations of the liver with 130 kVp using the calculated water-equivalent-diameter of the patients. The analysis platform was used for the calculation of the organ-specific effective dose (ED) as well as global radiation-dose parameters (ICRP103).

Results

The organ-specific ED of the dVPCT protocol was statistically significantly lower when compared to the sCT in 14 of 21, and noninferior in a total of 18 of 21 examined items (all p < 0.05). The EDs of the dVPCT examinations were especially in the dose sensitive organs such as the red marrow (17.3 mSv vs 24.6 mSv, p = < 0.0001) and the liver (33.3 mSv vs 46.9 mSv, p = 0.0003) lower when compared to the sCT.

Conclusion

Our results suggest that dVPCT performed at 70 or 80 kVp compares favorably to sCT performed with 130 kVp with regard to effective organ dose levels, especially in dose sensitive organs, while providing additional functional information which is of paramount importance in patients undergoing novel targeted therapies.

The Changes of HIF-1α and VEGF Expression After TACE in Patients With Hepatocellular Carcinoma

As a common malignant tumor, hepatocellular carcinoma (HCC) has a high prevalence and is a serious threat to human health. The surgical resection rate of HCC is low, and the prognosis is poor. Although transarterial chemoembolization (TACE) is the main treatment for HCC patients who are not candidates for surgical resection, it is not considered a curative procedure. For HCC, poor TACE efficacy or TACE failure may be related to tumor angiogenesis of the residual disease. Among the many regulatory factors in tumor angiogenesis, hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) play vital roles in this process. In this paper, we conducted a review of the dynamic change and relevance of HIF-1α and VEGF levels after TACE of HCC patients.

Imaging of HCC-Current State of the Art

Early diagnosis of hepatocellular carcinoma (HCC) is crucial for optimizing treatment outcome. Ongoing advances are being made in imaging of HCC regarding detection, grading, staging, and also treatment monitoring. This review gives an overview of the current international guidelines for diagnosing HCC and their discrepancies as well as critically summarizes the role of magnetic resonance imaging (MRI) and computed tomography (CT) techniques for imaging in HCC. The diagnostic performance of MRI with nonspecific and hepatobililiary contrast agents and the role of functional imaging with diffusion-weighted imaging will be discussed. On the other hand, CT as a fast, cheap and easily accessible imaging modality plays a major role in the clinical routine work-up of HCC. Technical advances in CT, such as dual energy CT and volume perfusion CT, are currently being explored for improving detection, characterization and staging of HCC with promising results. Cone beam CT can provide a three-dimensional analysis of the liver with tumor and vessel characterization comparable to cross-sectional imaging so that this technique is gaining an increasing role in the peri-procedural imaging of HCC treated with interventional techniques.