Hepatocellular carcinoma: evaluation of therapeutic response to interventional procedures

Apparent Diffusion Coefficient Can Predict Therapy Response of Hepatocellular Carcinoma to Transcatheter Arterial Chemoembolization

AIM

The goal of this meta-analysis was to assess the apparent diffusion coefficient (ADC) as a pre- and posttreatment (ADC value changes [ΔADC]) predictive imaging biomarker of response to transcatheter arterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC).

METHODS

Scopus database, Embase database, and MEDLINE library were scanned for connections between pre- and posttreatment ADC values of HCC and response to TACE. Six studies qualified for inclusion. The following parameters were collected: authors, publication year, study design, number of patients, drugs for TACE, mean ADC value, standard deviation, measure method, b values, and Tesla strength. The Quality Assessment of Diagnostic Studies 2 instrument was employed to check the methodological quality of each study. The meta-analysis was performed by utilizing RevMan 5.3 software. DerSimonian and Laird random-effects models with inverse-variance were used to regard heterogeneity. The mean ADC values and 95% confidence intervals were computed.

RESULTS

Six studies (n = 271 patients with 293 HCC nodules) were included. The pretreatment mean ADC in the responder group was 1.20 × 10-3 mm2/s (0.98, 1.42) and 1.14 × 10-3 mm2/s (0.89, 1.39) in the nonresponder group. The analysis of post-TACE ΔADC revealed a threshold of ≥20% to identify treatment responders. No suitable pretreatment ADC threshold to predict therapy response or discriminate between responders and nonresponders before therapy could be discovered.

CONCLUSION

ΔADC can facilitate early objective response evaluation through post-therapeutic ADC alterations ≥20%. Pretreatment ADC cannot predict response to TACE.

Intraarterial Therapies for the Management of Hepatocellular Carcinoma

Image-guided locoregional therapies play a crucial role in the management of patients with hepatocellular carcinoma (HCC). Transarterial therapies consist of a group of catheter-based treatments where embolic agents are delivered directly into the tumor via their supplying arteries. Some of the transarterial therapies available include bland embolization (TAE), transarterial chemoembolization (TACE), drug-eluting beads-transarterial chemoembolization (DEB-TACE), selective internal radioembolization therapy (SIRT), and hepatic artery infusion (HAI). This article provides a review of pre-procedural, intra-procedural, and post-procedural aspects of each therapy, along with a review of the literature. Newer embolotherapy options and future directions are also briefly discussed.

Doxorubicin-Loaded UiO-66/Bi2S3 Nanocomposite-Enhanced Synergistic Transarterial Chemoembolization and Photothermal Therapy against Hepatocellular Carcinoma

Transcatheter arterial chemoembolization (TACE) is the first choice for patients with intermediate hepatocellular carcinoma (HCC), but clinical applications still face some problems, such as the difficulties in clearing all cancer cells and lack of targeting, which would damage normal liver cells. Recently, photothermal therapy (PTT) and nanodelivery systems have been used to improve the efficacy of TACE. However, most of these strategies achieve only a single function, and the synthesis process is complicated. Here, a simple one-step solvothermal method was used to develop multifunctional nanoparticles (UiO-66/Bi₂S₃@DOX), which can simultaneously achieve photothermal effects and low pH-triggered DOX release. UiO-66/Bi₂S₃ exhibited a pH-responsive release behavior and an excellent photothermal effect in a series of in vitro and in vivo studies. Biocompatibility was confirmed by cytotoxicity and hemocompatibility evaluations. The rat N1S1 liver tumor model was established to investigate the therapeutic effect and biosafety of the nanoplatforms using TACE. The results revealed that the combination of TACE and PTT resulted in remarkable tumor growth inhibition, and the histopathological assay further revealed extensive necrosis, downregulated angiogenesis, increased apoptosis, and proliferation in the tumor response. These results demonstrated that this nanosystem platform was a promising therapeutic agent for enhancing TACE therapy for HCC treatment.

Role of multislice computed tomography 3D volumetric analysis in the assessment of the therapeutic response of hepatocellular carcinoma after transarterial chemoembolization

Background

Volumetric analysis is a novel radiological technique used in the measurement of target lesions in three dimensions in order to estimate the lesion’s volume. Recently, it has been used for evaluation of the remaining liver volume after partial hepatectomy and also for evaluation of the response of tumours to treatment. It has been proven to be more accurate than the standard one or two-dimensional measurements, and it is especially useful for the evaluation of complex tumours after radiological interventional methods when the use of standard methods is limited. In the current study, our aim was to evaluate the value of the three-dimensional (3D) volumetric method “Response Evaluation Criteria in Solid Tumours (vRECIST)” and to compare it with the non–three-dimensional methods (RECIST) and modified RECIST (mRECIST) in the assessment of the therapeutic response of hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE).

Results

A retrospective study was conducted on 50 patients with confirmed radiological or pathological diagnosis of hepatocellular carcinoma (HCC) who underwent TACE as the only interventional procedure and follwed up by triphasic CT 1 and 4 months after treatment. The study revealed a significant difference between mRECIST and vRECIST in the assessment of the therapeutic response of HCC after TACE, a weak agreement was found between both methods in the detection of complete response (CR), partial response (PR), stable disease (SD) or progressive disease (PD). Also, there was no significant agreement between mRECIST and vRECIST regarding the assessment by classifying the patients into responders or nonresponders.

Conclusion

Volumetric analysis is an effective method for measuring the HCC lesions and evaluating its response to locoregional treatment with a significant difference between vRECIST and mRECIST in the assessment of therapeutic response, which in turn help the interventional radiologist to decide the future treatments and change the therapeutic plans. Based on these results, we recommend vRECIST to be an essential part of the assessment of therapeutic response after locoregional therapy.

Quantification of Functional MR Predicts Early Response in Post-doxorubicin Drug-Eluting Beads Chemoembolization for Hepatocellular Carcinoma

BACKGROUND

The purpose of this study was to assess the value of functional MRI (fMRI) of post-doxorubicin drug-eluting beads transcatheter arterial chemoembolization (DEB-TACE) for hepatocellular carcinoma (HCC) as an early imaging biomarker of response to therapy.

METHODS

This prospective analysis included 21 consecutive patients undergoing fMRI before and after DEB-TACE at a single medical center from January 2013 to December 2014. Functional MRI, including relative changes in apparent diffusion coefficient (ADC) and choline levels measured at hydrogen-1 magnetic resonance spectroscopy (MRS) of treated lesions, was recorded at baseline before DEB-TACE, and at 1, 2, and 4 weeks after DEB-TACE therapy. Assessment of tumor response was based on dynamic contrast-enhanced computer tomography imaging response according to modified response evaluation criteria in solid tumors.

RESULTS

At post-therapy, 76% (n = 16) of patients demonstrated objective tumor response, 10% (n = 2) had stable disease, and 3 (14%) had progressive disease. Stable disease and progressive disease were designated as non-response. At week 2, the mean change in ADC value of responsive tumors was 0.35 ± 0.24 mm²/s, which was greater than that of non-response tumors (mean 0.01 ± 0.13 × 10^-3 mm²/s) (P = 0.006). Significant differences were found in mean choline/water ratio between responsive (7.8 ± 4.9 × 10^-3) and non-responsive (17.2 ± 4.9 × 10^-3) tumors (P = 0.005). Composite scores of choline/water ratio and relative change of ADC showed significantly better diagnostic accuracy in non-responsive tumors than responsive tumors (area under the curve = 1.0; P < 0.001).

CONCLUSIONS

Combined DWI and MRS may be used as an early imaging biomarker of therapy response in HCC patients after chemoembolization therapy.

Early assessment of coagulation necrosis after hepatic microwave ablation: a comparison of non-enhanced and enhanced T1-weighted images

PURPOSE

To compare the technical success and accuracy of hepatic microwave ablation (MWA) using non-enhanced and enhanced T1-weighted imaging early after ablation. Patients were evaluated with regard to the ablation zone and local tumor progression (LTP).

METHODS

This retrospective study conducted between September 2014 and December 2015 which consisted of 56 patients with 56 hepatic malignant lesions who underwent percutaneous MWA. Non-enhanced and contrast-enhanced T1-weighted imagings were performed within 2 days after tumor ablation. The efficacy of ablation assessed according to the hyperintense middle zone on non-enhanced T1-weighted images and the non-enhanced area on contrast-enhanced T1-weighted images were compared. The development of LTP during ≥7 months of follow-up served as the end point.

RESULTS

On the non-enhanced T1-weighted images, the ablated region had a characteristic two-zone structure featuring a hyperintense middle zone and a surrounding hypointense band. Among the 56 patients, LTP developed in ten including seven lesions, in which both the non-enhanced T1-weighted and portal-phase images showed incomplete tumor ablation. In two of the remaining three patients, incomplete tumor ablation was detected on the non-enhanced T1-weighted images, whereas the corresponding portal-phase images showed complete ablation. In the remaining patient, no residual tumor was detected on either the non-enhanced T1-weighted or the portal-phase images. In the 46 patients without LTP, there was no evidence of residual tumor on the non-enhanced T1-weighted or portal-phase images obtained early after ablation.

CONCLUSIONS

Non-enhanced T1-weighted images are useful in assessing the therapeutic efficacy of MWA of liver tumors early after the procedure.

Intra-arterial therapies for liver cancer: assessing tumor response

INTRODUCTION

Intra-arterial therapies (IATs) play an integral role in the management of unresectable hepatocellular carcinoma and liver metastases. The ability to accurately assess tumor response to intra-arterial therapies is crucial for clinical management. Several one- and two-dimensional manual imaging-based response assessment techniques, based both on tumor size or enhancement, have shown to be highly subjective and merely surrogate for the actual tumor as a whole. Areas covered: Given the currently existing literature, we will discuss all available tumor assessment techniques and criteria for liver cancer with a strong emphasis on 3D quantitative imaging biomarkers of tumor response in this review. Expert commentary: The growing role of information technology in medicine has brought about the advent of software-assisted, segmentation-based assessment techniques that address the outstanding issues of a subjective reader and provide for more accurate assessment techniques for the locally treated lesions. Three-dimensional quantitative tumor assessment techniques are superior to one- and two-dimensional measurements. This allows for treatment alterations and more precise targeting, potentially resulting in improved patient outcome.

Advanced imaging techniques in the therapeutic response of transarterial chemoembolization for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the major causes of morbidity and mortality in patients with chronic liver disease. Transarterial chemoembolization (TACE) can significantly improve the survival rate of patients with HCC and is the first treatment choice for patients who are not suitable for surgical resections. The evaluation of the response to TACE treatment affects not only the assessment of the therapy efficacy but also the development of the next step in the treatment plan. The use of imaging to examine changes in tumor volume to assess the response of solid tumors to treatment has been controversial. In recent years, the emergence of new imaging technology has made it possible to observe the response of tumors to treatment prior to any morphological changes. In this article, the advances in studies reporting the use of computed tomography perfusion imaging, diffusion-weighted magnetic resonance imaging (MRI), intravoxel incoherent motion, diffusion kurtosis imaging, magnetic resonance spectroscopy, magnetic resonance perfusion-weighted imaging, blood oxygen level-dependent MRI, positron emission tomography (PET)/computed tomography and PET/MRI to assess the TACE treatment response are reviewed.

Hepatic imaging following intra-arterial embolotherapy

PURPOSE

To discuss guidelines and salient imaging findings of solid tumors treated with common intra-arterial procedures used in interventional oncology.

METHODS

A meticulous literature search of PubMed-indexed articles was conducted. Key words included "imaging + embolization," "imaging + TACE," "imaging + radioembolization," "imaging + Y90," "mRECIST," and "EASL." Representative post-treatment cross-sectional images were obtained from past cases in this institution.

RESULTS

Intra-arterial therapy (IAT) in interventional oncology includes bland embolization, chemoembolization, and radioembolization. Solid tumors of the liver are the primary focus of these procedures. Cross-sectional CT and/or MR are the main modalities used to image tumors after treatment. Traditional size-based response criteria (WHO and RECIST) alone are of limited utility in determining response to IAT; tumoral necrosis and enhancement must be considered. Specifically for HCC, the EASL and mRECIST guidelines are becoming widely adopted response criteria to assess these factors. DWI, FDG-PET, and CEUS are modalities that play an adjunctive but controversial role.

CONCLUSIONS

Radiologists must be aware that the different forms of intra-arterial therapy yield characteristic findings on cross-sectional imaging. Knowledge of these findings is integral to accurate assessment of tumor response and progression.

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.

Immediate post-doxorubicin drug-eluting beads chemoembolization Mr Apparent diffusion coefficient quantification predicts response in unresectable hepatocellular carcinoma: A pilot study

PURPOSE

To investigate magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) of hepatocellular carcinoma (HCC) immediately post-doxorubicin drug-eluting beads transcatheter arterial chemoembolization (DEB-TACE) therapy as an early imaging biomarker of therapy response.

MATERIALS AND METHODS

In a single-center prospective correlative study, 12 consecutive patients, median age 64 years, underwent DEB-TACE and dynamic contrast-enhanced (DCE) and DWI (b = 50,400,800 s/mm(2)) MRI at baseline with respect to first DEB-TACE, within 3 hours, and at 1 and 3 months posttherapy. DCE imaging response was evaluated according to target mRECIST and EASL. Relative change (RC) in apparent diffusion coefficient (ADC) of treated lesions was measured on follow-ups. Correlation between ADC RC in tumors and anatomical response were evaluated with paired t-test and receiver operator characteristic (ROC) curve. Survival from first DEB-TACE was estimated using Kaplan-Meier and log-rank analysis.

RESULTS

Compared to baseline, mean ADC increased significantly for responders within 3 hours post-DEB-TACE (0.73 ± 0.20 mm(2) /s vs. 0.99 ± 0.28 mm(2) /s × 10(-3) (P = 0.001)). There was no significant change in ADC within 3 hours for nonresponders. ADC RC threshold of 20% immediately post-DEB-TACE showed 100% sensitivity and specificity in predicting anatomical response at 1 and 3 months with patients with ≥20% ADC increase demonstrated significantly prolonged mean overall survival compared to others (25.4 vs. 13.3 months (P = 0.017)).

CONCLUSION

ADC relative change of ≥20% immediately post-DEB-TACE is an accurate predictor of objective and quantitative treatment response and prolonged survival in unresectable HCC.

Quantitative and volumetric European Association for the Study of the Liver and Response Evaluation Criteria in Solid Tumors measurements: feasibility of a semiautomated software method to assess tumor response after transcatheter arterial chemoembolization

PURPOSE

To show that hepatic tumor volume and enhancement pattern measurements can be obtained in a time-efficient and reproducible manner on a voxel-by-voxel basis to provide a true three-dimensional (3D) volumetric assessment.

MATERIALS AND METHODS

Magnetic resonance (MR) imaging data obtained from 20 patients recruited for a single-institution prospective study were retrospectively evaluated. All patients had a diagnosis of hepatocellular carcinoma (HCC) and underwent drug-eluting beads (DEB) transcatheter arterial chemoembolization for the first time. All patients had undergone contrast-enhanced MR imaging before and after DEB transcatheter arterial chemoembolization; poor image quality excluded 3 patients, resulting in a final count of 17 patients. Volumetric RECIST (vRECIST) and quantitative EASL (qEASL) were measured, and segmentation and processing times were recorded.

RESULTS

There were 34 scans analyzed. The time for semiautomatic segmentation was 65 seconds±33 (range, 40-200 seconds). vRECIST and qEASL of each tumor were computed<1 minute for each.

CONCLUSIONS

Semiautomatic quantitative tumor enhancement (qEASL) and volume (vRECIST) assessment is feasible in a workflow-efficient time frame. Clinical correlation is necessary, but vRECIST and qEASL could become part of the assessment of intraarterial therapy for interventional radiologists.

Semiautomatic volumetric tumor segmentation for hepatocellular carcinoma: comparison between C-arm cone beam computed tomography and MRI

RATIONALE AND OBJECTIVES

To evaluate the precision and reproducibility of a semiautomatic tumor segmentation software in measuring tumor volume of hepatocellular carcinoma (HCC) before the first transarterial chemo-embolization (TACE) on contrast-enhancement magnetic resonance imaging (CE-MRI) and intraprocedural dual-phase C-arm cone beam computed tomography (DP-CBCT) images.

MATERIALS AND METHODS

Nineteen HCCs were targeted in 19 patients (one per patient) who underwent baseline diagnostic CE-MRI and an intraprocedural DP-CBCT. The images were obtained from CE-MRI (arterial phase of an intravenous contrast medium injection) and DP-CBCT (delayed phase of an intra-arterial contrast medium injection) before the actual embolization. Three readers measured tumor volumes using a semiautomatic three-dimensional volumetric segmentation software that used a region-growing method employing non-Euclidean radial basis functions. Segmentation time and spatial position were recorded. The tumor volume measurements between image sets were compared using linear regression and Student's t-test, and evaluated with intraclass-correlation analysis (ICC). The inter-rater Dice similarity coefficient (DSC) assessed the segmentation spatial localization.

RESULTS

All 19 HCCs were analyzed. On CE-MRI and DP-CBCT examinations, respectively, 1) the mean segmented tumor volumes were 87 ± 8 cm(3) (2-873) and 92 ± 10 cm(3) (1-954), with no statistical difference of segmented volumes by readers of each tumor between the two imaging modalities and the mean time required for segmentation was 66 ± 45 seconds (21-173) and 85 ± 34 seconds (17-214) (P = .19); 2) the ICCs were 0.99 and 0.974, showing a strong correlation among readers; and 3) the inter-rater DSCs showed a good to excellent inter-user agreement on the spatial localization of the tumor segmentation (0.70 ± 0.07 and 0.74 ± 0.05, P = .07).

CONCLUSION

This study shows a strong correlation, a high precision, and excellent reproducibility of semiautomatic tumor segmentation software in measuring tumor volume on CE-MRI and DP-CBCT images. The use of the segmentation software on DP-CBCT and CE-MRI can be a valuable and highly accurate tool to measure the volume of hepatic tumors.

Comparison of semi-automatic volumetric VX2 hepatic tumor segmentation from cone beam CT and multi-detector CT with histology in rabbit models

RATIONALE AND OBJECTIVES

The purpose of this study was to compare tumor volume in a VX2 rabbit model as calculated using semiautomatic tumor segmentation from C-arm cone-beam computed tomography (CBCT) and multidetector computed tomography (MDCT) to the actual tumor volume.

MATERIALS AND METHODS

Twenty VX2 tumors in 20 adult male New Zealand rabbits (one tumor per rabbit) were imaged with CBCT (using an intra-arterial contrast medium injection) and MDCT (using an intravenous contrast injection). All tumor volumes were measured using semiautomatic three-dimensional volumetric segmentation software. The software uses a region-growing method using non-Euclidean radial basis functions. After imaging, the tumors were excised for pathologic volume measurement. The imaging-based tumor volume measurements were compared to the pathologic volumes using linear regression, with Pearson's test, and correlated using Bland-Altman analysis.

RESULTS

Average tumor volumes were 3.5 ± 1.6 cm(3) (range, 1.4-7.2 cm(3)) on pathology, 3.8 ± 1.6 cm(3) (range, 1.3-7.3 cm(3)) on CBCT, and 3.9 ± 1.6 (range, 1.8-7.5 cm(3)) on MDCT (P < .001). A strong correlation between volumes on pathology and CBCT and also with MDCT was observed (Pearson's correlation coefficient = 0.993 and 0.996, P < .001, for CBCT and MDCT, respectively). Bland-Altman analysis showed that MDCT tended to overestimate tumor volume, and there was stronger agreement for tumor volume between CBCT and pathology than with MDCT, possibly because of the intra-arterial contrast injection.

CONCLUSIONS

Tumor volume as measured using semiautomatic tumor segmentation software showed a strong correlation with the "real volume" measured on pathology. The segmentation software on CBCT and MDCT can be a useful tool for volumetric hepatic tumor assessment.

Intraprocedural C-arm dual-phase cone-beam CT: can it be used to predict short-term response to TACE with drug-eluting beads in patients with hepatocellular carcinoma?

PURPOSE

To investigate whether C-arm dual-phase cone-beam computed tomography (CT) performed during transcatheter arterial chemoembolization (TACE) with doxorubicin-eluting beads can help predict tumor response at 1-month follow-up in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This prospective study was compliant with HIPAA and approved by the institutional review board and animal care and use committee. Analysis was performed retrospectively on 50 targeted HCC lesions in 29 patients (16 men, 13 women; mean age, 61.9 years ± 10.7) treated with TACE with drug-eluting beads. Magnetic resonance (MR) imaging was performed at baseline and 1 month after TACE. Dual-phase cone-beam CT was performed before and after TACE. Tumor enhancement at dual-phase cone-beam CT in early arterial and delayed venous phases was assessed retrospectively with blinding to MR findings. Tumor response at MR imaging was assessed according to European Association for the Study of the Liver (EASL) guidelines. Two patients were excluded from analysis because dual-phase cone-beam CT scans were not interpretable. Logistic regression models for correlated data were used to compare changes in tumor enhancement between modalities. The radiation dose with dual-phase cone-beam CT was measured in one pig.

RESULTS

At 1-month MR imaging follow-up, complete and/or partial tumor response was seen in 74% and 76% of lesions in the arterial and venous phases, respectively. Paired t tests used to compare images obtained before and after TACE showed a significant reduction in tumor enhancement with both modalities (P < .0001). The decrease in tumor enhancement seen with dual-phase cone-beam CT after TACE showed a linear correlation with MR findings. Estimated correlation coefficients were excellent for first (R = 0.89) and second (R = 0.82) phases. A significant relationship between tumor enhancement at cone-beam CT after TACE and complete and/or partial tumor response at MR imaging was found for arterial (odds ratio, 0.95; 95% confidence interval [CI]: 0.91, 0.99; P = .023) and venous (odds ratio, 0.96; 95% CI: 0.93, 0.99; P = .035) phases with the multivariate logistic regression model. Radiation dose for two dual-phase cone-beam CT scans was 3.08 mSv.

CONCLUSION

Intraprocedural C-arm dual-phase cone-beam CT can be used immediately after TACE with doxorubicin-eluting beads to predict HCC tumor response at 1-month MR imaging follow-up.

Advances in image-guided intratumoral drug delivery techniques

Image-guided drug delivery provides a means for treating a variety of diseases with minimal systemic involvement while concurrently monitoring treatment efficacy. These therapies are particularly useful to the field of interventional oncology, where elevation of tumor drug levels, reduction of systemic side effects and post-therapy assessment are essential. This review highlights three such image-guided procedures: transarterial chemoembolization, drug-eluting implants and convection-enhanced delivery. Advancements in medical imaging technology have resulted in a growing number of new applications, including image-guided drug delivery. This minimally invasive approach provides a comprehensive answer to many challenges with local drug delivery. Future evolution of imaging devices, image-acquisition techniques and multifunctional delivery agents will lead to a paradigm shift in patient care.

Usefulness of F-18 FDG PET/CT in the Evaluation of Early Treatment Response After Interventional Therapy for Hepatocellular Carcinoma

PURPOSE

This retrospective study investigated the usefulness of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) after interventional therapy for hepatocellular carcinoma (HCC).

METHODS

Between March 2007 and November 2010, 31 patients (24 men, 7 women; mean age, 61.8 ± 11.0 years) with 45 lesions underwent PET/CT within 1 month after interventional therapy for HCC. Twenty-six patients with 40 lesions underwent transcatheter arterial chemoembolization (TACE), two patients with 2 lesions underwent radiofrequency ablation (RFA), and three patients with 3 lesions underwent percutaneous ethanol injection therapy (PEIT). Patients with a history of previous interventional therapy were excluded. Visual analysis was graded as positive when FDG was observed as an eccentric, nodular, or infiltrative pattern, and negative in case of isometabolic, hypometabolic, or rim-shaped uptake. For quantitative analysis, the standardized uptake value (SUV) was measured by region of interest technique. Maximum SUV (SUVmax) was assessed, and the ratio of SUVmax of tumor to mean SUV of normal liver (TNR) was calculated. The patients were divided into two groups, with and without residual tumor, based on 6-month clinical follow-up with serum alpha-fetoprotein and contrast-enhanced abdominal CT.

RESULTS

Of the 45 lesions, 24 were classified in the residual tumor group and the other 21 lesions in the no residual tumor group. No residual tumor was detected after RFA or PEIT. By visual analysis, the respective values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.5, 71.4, 77.8, 83.3, and 80.0 %. However, there were no significant differences in the SUVmax and TNR between the two groups.

CONCLUSIONS

It is suggested that FDG PET/CT may play a role in the evaluation of early treatment response after interventional therapy for HCC. The results indicate that FDG PET/CT visual analysis may be more useful than quantitative analysis. Further prospective studies with a large number of patients and established protocol are needed to substantiate our results.

Computed tomographic perfusion imaging for the therapeutic response of chemoembolization for hepatocellular carcinoma

BACKGROUND

Computed tomographic (CT) perfusion imaging has been applied in many clinical areas, but few studies have addressed the values of CT perfusion imaging in evaluating the therapeutic response of chemoembolization for hepatocellular carcinoma (HCC).

OBJECTIVE

To assess the perfusion changes of HCC after transarterial chemoembolization, and to investigate the values of CT perfusion imaging in chemoembolization procedure.

METHODS

Multidetector computed tomographic perfusion imaging was performed in 24 patients with HCC 1 week before and 4 weeks after chemoembolization. The CT perfusion parameters, including hepatic arterial perfusion (HAP), hepatic portal perfusion (HPP), total liver perfusion (TLP), and hepatic arterial perfusion index (HAPI), were calculated by using the slope method. The t statistic was used to analysis the difference of CT perfusion parameter values before and after chemoembolization therapy.

RESULTS

The values of HAP, TLP, and HAPI in tumors 4 weeks after chemoembolization were significantly decreased than those before chemoembolization (P < 0.05), but the value of HPP in tumors was not (P > 0.05).

CONCLUSION

Computed tomographic perfusion imaging has the ability to evaluate the perfusion changes in HCC after chemoembolization, which can be used to evaluate the therapeutic response of chemoembolization for hepatocellular carcinoma.

Diffusion-weighted magnetic resonance imaging to predict response of hepatocellular carcinoma to chemoembolization

AIM: To investigate whether intra-procedural diffusion-weighted magnetic resonance imaging can predict response of hepatocellular carcinoma (HCC) during transcatheter arterial chemoembolization (TACE).

METHODS: Sixteen patients (15 male), aged 59 ± 11 years (range: 42-81 years) underwent a total of 21 separate treatments for unresectable HCC in a hybrid magnetic resonance/interventional radiology suite. Anatomical imaging and diffusion-weighted imaging (b = 0, 500 s/mm²) were performed on a 1.5-T unit. Tumor enhancement and apparent diffusion coefficient (ADC, mm²/s) values were assessed immediately before and at 1 and 3 mo after TACE. We calculated the percent change (PC) in ADC values at all time points. We compared follow-up ADC values to baseline values using a paired t test (α = 0.05).

RESULTS: The intra-procedural sensitivity, specificity, and positive and negative predictive values (%) for detecting a complete or partial 1-mo tumor response using ADC PC thresholds of ±5%, ±10%, and ±15% were 77, 67, 91, and 40; 54, 67, 88, and 25; and 46, 100, 100, and 30, respectively. There was no clear predictive value for the 3-mo follow-up. Compared to baseline, the immediate post-procedure and 1-mo mean ADC values both increased; the latter obtaining statistical significance (1.48 ± 0.29 mm²/s vs 1.65 ± 0.35 × 10^-3 mm²/s, P < 0.014).

CONCLUSION: Intra-procedural ADC changes of > 15% predicted 1-mo anatomical HCC response with the greatest accuracy, and can provide valuable feedback at the time of TACE.

Comparison of gadoxetic acid-enhanced MR imaging versus four-phase multi-detector row computed tomography in assessing tumor regression after radiofrequency ablation in subjects with hepatocellular carcinomas

PURPOSE

To assess the diagnostic value of gadoxetic acid-enhanced magnetic resonance (MR) imaging in follow-up of patients with hepatocellular carcinomas (HCCs) who were treated with radiofrequency (RF) ablation and to compare it with that of four-phase multi-detector row computed tomography (CT).

MATERIALS AND METHODS

From July 2007 to May 2008, 36 patients (43 HCCs) were enrolled who were treated with RF ablation (tumor size, 20-47 mm; mean, 24.5 mm) and underwent gadoxetic acid-enhanced MR imaging and four-phase (precontrast, arterial, portal venous, and equilibrium) multidetector CT for follow-up. Two radiologists independently reviewed these images, and conspicuity of tumor margins and detection of residual or recurrent tumor were assessed on a five-point scale with receiver operating characteristic (ROC) curve analysis. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were evaluated.

RESULTS

The mean conspicuity value of tumor margins was significantly higher on MR imaging than on multidetector CT (P < .001). The degree of differentiation between residual/recurrent tumor and hyperemia was significantly greater on MR imaging (P < .001). The mean area under the ROC curve was significantly higher with MR imaging (P = .015), as were sensitivity, specificity, PPV, NPV, and accuracy of detection rate (mean, 100%, 96.2%, 82.4%, 100%, and 96.7%, respectively, vs 41.7%, 56.8%, 13.5%, 85.7%, and 54.7% for multidetector CT). The interobserver agreement rate for MR imaging was higher (0.919) than for multidetector CT (0.672; P < .05).

CONCLUSIONS

Diagnostic accuracy, conspicuity of tumor margins, and detection rate of residual or recurrent tumor were found to be better with gadoxetic acid-enhanced MR imaging than with four-phase multidetector CT.

Unresectable hepatocellular carcinoma: serial early vascular and cellular changes after transarterial chemoembolization as detected with MR imaging

PURPOSE

To prospectively assess serial changes in contrast material-enhanced and diffusion-weighted (DW) magnetic resonance (MR) imaging values within 1 month after transarterial chemoembolization (TACE) in patients with unresectable hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Institutional review board approval was obtained for this prospective HIPAA-compliant study. MR imaging was performed before and within 24 hours after TACE in 24 patients with HCC (21 male, three female; mean age, 59 years and 62 years, respectively). Serial MR imaging was subsequently performed 1, 2, 3, and 4 weeks after therapy. The imaging protocol included fast spin-echo T2-weighted MR imaging, breath-hold DW echo-planar MR imaging, and breath-hold unenhanced and contrast-enhanced T1-weighted three-dimensional fat-suppressed gradient-recalled-echo MR imaging in the arterial and portal venous phases. Tumor size, enhancement, and apparent diffusion coefficient (ADC) values were recorded before and sequentially after treatment. Regression models for the correlated data were used to assess changes in these parameters over time after TACE.

RESULTS

Mean tumor size was 7.5 cm and was unchanged up to 4 weeks after therapy. Reduction in tumor enhancement in the arterial phase occurred immediately after TACE, with a consistent reduction occurring 1-3 weeks after therapy (P = .001). Reduction in tumor enhancement in the portal venous phase also occurred immediately after TACE, with a consistent reduction occurring 1-3 weeks after therapy (P = .0003). The increase in tumor ADC value was significant 1-2 weeks after therapy (P = .004), borderline significant 3 weeks after therapy, and insignificant 24 hours and 4 weeks after therapy.

CONCLUSION

Significant reduction in tumor enhancement occurred within 24 hours after TACE and persisted up to 4 weeks after TACE. Lesser changes in the ADC value appeared 1 week after TACE, persisted through 2 weeks after TACE, and became less apparent 3 and 4 weeks after TACE. No change in tumor size was recorded during the follow-up period.

Hepatocellular carcinoma treated with radio frequency ablation: an early evaluation with magnetic resonance imaging

PURPOSE

To determine the usefulness of nonenhanced T1-weighted spoiled gradient-recalled acquisition in the steady-state (SPGR) MRI in the early assessment of the efficacy of radio frequency (RF) therapy for hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

A total of 23 patients with 28 HCC nodules treated with percutaneous RF ablation underwent nonenhanced MRI within two days after the RF procedure and contrast-enhanced computed tomography (CT) one week after. MR assessment of ablation efficacy according to the concentric zonal pattern on T1-weighted SPGR imaging was compared with the one-week CT and presence of local recurrence by means of follow-up study for 12 months or more.

RESULTS

In 18 of 28 ablated nodules, SPGR images revealed a central hyperintense zone covering the entire tumor, CT showed a nonenhanced area covering the entire tumor, and no local recurrence was demonstrated in the follow-up studies. In nine of 28 nodules, the central hyperintense zone did not cover the entire tumor; and local recurrence was demonstrated in three nodules. In the remaining one nodule, no signal change was seen in the treated area on SPGR images and CT showed the presence of residual viable tumor.

CONCLUSION

Nonenhanced T1-weighted MRI was considered useful for early assessment of the efficacy of RF therapy for HCC.

Assessment of metastatic breast cancer response to chemoembolization with contrast agent enhanced and diffusion-weighted MR imaging

PURPOSE

To assess the value of functional magnetic resonance (MR) imaging in the evaluation of early tumor response after transarterial chemoembolization (TACE) for metastatic breast cancer and to compare tumor response based on functional MR imaging versus traditional assessment based on iodized oil deposition, tumor size, and tumor enhancement.

MATERIALS AND METHODS

For 14 patients with metastatic breast cancer, MR imaging studies before and after TACE were evaluated. Diffusion and contrast medium-enhanced MR imaging was performed on a 1.5-T unit. Parameters evaluated included change in tumor size, enhancement, and apparent diffusion coefficient (ADC) values. Median survival was also calculated in the entire cohort.

RESULTS

A total number of 27 lesions were evaluated, with a mean diameter of 5.5 cm. Although mean tumor size decreased by 18% after treatment, no tumors met the Response Evaluation Criteria In Solid Tumors (RECIST) for complete response (ie, complete disappearance of target lesions) and only seven of 27 met RECIST for partial response (ie, >30% decrease in target lesion size). After treatment, decrease of tumor enhancement in the arterial (32%) and portal venous (39%) phases was statistically significant (P < .0001). Mean tumor ADC increased by 27% (P < .0001) after TACE, whereas ADC remained unchanged in nontumorous liver, spleen, and kidney. Median survival was 25 months for the entire cohort.

CONCLUSION

In patients with breast cancer and liver metastases who were treated with TACE, although changes in tumor size were small, significant early changes in the treated lesions occurred on contrast medium-enhanced and functional MR imaging. These include decrease in tumor enhancement and increase in tumor ADC value, which suggest increasing tumor necrosis and cell death.

Transcatheter arterial chemoembolization: current technique and future promise

Transarterial chemoembolization is the mainstay of catheter based interventional oncologic therapies. This article describes the history of the procedure, selection of appropriate candidates, technical aspects of procedure performance, results, complications, and appropriate follow-up. In addition, the limitations and challenges of the procedure are outlined. Finally, the reader is introduced to novel and promising techniques and devices that hold future promise for transarterial therapy of malignancies.

Comparison of contrast enhanced ultrasound and contrast enhanced CT or MRI in monitoring percutaneous thermal ablation procedure in patients with hepatocellular carcinoma: a multi-center study in China

To evaluate the ability of contrast enhanced ultrasound (CEUS) in monitoring percutaneous thermal ablation procedure in patients with hepatocellular carcinoma (HCC) in comparison with contrast enhanced computed tomography (CECT) and/or magnetic resonance imaging (CEMRI). A total of 151 patients were enrolled in the study. Before the radio-frequency (RF) or microwave ablation treatment, tumor vascularity was assessed in 139 patients with three imaging modalities i.e., US (139 exams), CEUS (139 exams) and CECT (103 exams)/CEMR (36 exams). CEUS examination was performed using a sulphur hexafluoride-filled microbubble contrast agent (SonoVue((R)), Bracco, Milan, Italy) and real-time contrast-specific imaging techniques. Within 30 +/- 7 d after the ablation procedure, 118/139 patients were monitored to assess the tumor response to treatment. Before ablation, contrast enhancement within tumor was observed in 129/139 (92.8%) patients with CEUS and 133/139 (95.7%) patients with CECT/CEMRI. Compared with CECT/CEMRI, CEUS sensitivity and accuracy in detecting tumor vascularity were 97.0% and 94.2%, respectively. One month after treatment, no enhancement was seen in 110/118 (93.2%) both on CEUS and CECT/CEMRI. Concordance between CEUS and CECT/CEMR on the presence of residual vascularization was obtained in four patients (true positive). The specificity and accuracy of CEUS in detecting tumor vascularity were 98.2% and 96.6%, respectively. The periprocedural impact of SonoVue administration on the assessment of treatment extent was also evaluated in a subgroup of patients and CEUS showed its superiority compared with baseline US in defining treatment outcome. In conclusion, in the detection of HCC tumor vascularity and assessment of response to thermal ablation after 1 month, real time CEUS provided results comparable to those obtained with CECT/CEMRI. CEUS examination proved to be a safe and easy to access procedure, with potential for diagnostic impact in the clinical practice.

Emerging approaches in hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) is predicted to continue to increase over the next 30 years. Surgical intervention, including resection and orthotopic liver transplantation (OLT) is offered to a limited number of patients. Novel approaches to the treatment of patients with HCC are needed. This article aims to review emerging approaches in the care of the HCC patient including systemic treatment, selection of appropriate candidates for OLT, improved imaging to follow treatment response, and management pre-OLT and post-OLT.

Transcatheter and ablative therapeutic approaches for solid malignancies

The purpose of this article is to present in a concise manner an overview of the most widely used locoregional transcatheter and ablative therapies for solid malignancies. An extensive MEDLINE search was performed for this review. Therapies used for liver cancer were emphasized because these therapies are used most commonly in the liver. Applications in pulmonary, renal, and bone tumors were also discussed. These approaches were divided into catheter-based therapies (such as transcatheter arterial chemoembolization, bland embolization, and the most recent transcatheter arterial approach with drug-eluting microspheres), ablative therapies (such as chemical [ethanol or acetic acid injection]), and thermal ablative therapies (such as radiofrequency ablation, laser induced thermotherapy, microwave ablation, cryoablation, and extracorporeal high-intensity focused ultrasound ablation). A brief description of each technique and analysis of available data was reported for all therapies. Locoregional transcatheter and ablative therapies continue to be used mostly for palliation, but have also been used with curative intent. A growing body of evidence suggests clear survival benefit, excellent results regarding local tumor control, and improved quality of life. Clinical trials are underway to validate these results. Image-guided transcatheter and ablative approaches currently play an important role in the management of patients with various types of cancer-a role that is likely to grow even more given the technological advances in imaging, image-guidance systems, catheters, ablative tools, and drug delivery systems. As a result, the outcomes of patients with cancer undoubtedly will improve.

Technology insight: Image-guided therapies for hepatocellular carcinoma--intra-arterial and ablative techniques

Locoregional techniques have become the mainstay of therapy for patients with unresectable hepatocellular carcinoma (HCC). Such image-guided interventions include catheter-based approaches (transarterial chemoembolization and yttrium-90 radiotherapy) and locoregional ablative techniques, either chemical (percutaneous ethanol injection), or thermal (radiofrequency ablation, laser ablation, microwave ablation and cryoablation). These therapies are mainly utilized for palliation, but have also been used with curative intent. In selected cases, percutaneous interventional treatments have shown good results (5-year survival 40-50%), but, even when chosen as first-line treatment, have not been able to achieve the response rates and outcomes achieved by surgical options (resection or transplantation). New promising image-guided therapies are continuously emerging, as we attempt to improve tumor targeting, minimize hepatic toxicity and ultimately improve quality of life and survival of patients with HCC. With new technologies in imaging and drug delivery becoming available, it is likely that, in the future, patients with HCC will be best treated by a multidisciplinary team approach, utilizing a combination of techniques to improve patient survival. This review outlines the current status of the most commonly used image-guided locoregional interventions in the treatment of patients with HCC, and describes recent research and advances related to image-guided interventions for liver cancer.

The role of functional MR imaging in the assessment of tumor response after chemoembolization in patients with hepatocellular carcinoma

PURPOSE

To assess treatment response of hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE) with use of diffusion and dynamic contrast medium-enhanced magnetic resonance (MR) imaging.

MATERIALS AND METHODS

MR imaging studies before and after TACE in 38 patients with HCC (33 male patients and five female patients) were evaluated. Diffusion and dynamic contrast medium-enhanced MR imaging was performed on a 1.5-T unit. The imaging protocol included T2-weighted fast spin-echo, breath-hold diffusion-weighted echoplanar, and breath-hold unenhanced and contrast medium-enhanced T1-weighted three-dimensional fat-saturation gradient-recalled echo imaging in the arterial and portal venous phases. Tumor size, percent enhancement, and apparent diffusion coefficient (ADC) values were recorded before and after treatment. Survival analysis was also performed.

RESULTS

The study included 38 lesions with a mean diameter of 8.0 cm. Mean reduction in tumor diameter was 8 mm after treatment (t test; P = .0005), which did not fulfill Response Evaluation Criteria in Solid Tumors for complete or partial response. Reduction in tumor enhancement in the arterial (30%) and venous (47%) phases was statistically significant (signed-rank test; P = .0003 and P < 0.00005, respectively). Tumor ADC value increased from 0.0015 mm(2)/sec to 0.0018 mm(2)/sec after treatment (t test; P = .026), whereas the ADC values for the liver, spleen, and muscle remained unchanged. Median patient survival was 19 months.

CONCLUSIONS

After TACE, tumors demonstrated decreased size and enhancement with increases in ADC values. In this cohort, diffusion and dynamic contrast medium-enhanced MR imaging parameters were significantly altered after TACE, and these could be useful tools in the assessment of tumor response.

Changes in bile ducts after radiofrequency ablation of hepatocellular carcinoma: frequency and clinical significance

OBJECTIVE

The purpose of our study was to determine the frequency of bile duct changes after radiofrequency ablation for hepatocellular carcinoma and to evaluate their clinical significance.

MATERIALS AND METHODS

Between April 1999 and August 2003, 389 patients with 521 hepatocellular carcinomas underwent a total of 571 sessions of radiofrequency ablation. The maximum dimension of the tumors measured on sonography was 2.4 +/- 0.9 cm (mean +/- SD) (range, 0.5-5.0 cm). The frequency and type of bile duct changes resulting from radiofrequency ablation, the time interval between radiofrequency ablation and the first appearance of bile duct changes, and the serial changes at follow-up CT were analyzed. Complications related to bile duct changes were also evaluated by reviewing medical records and CT scans.

RESULTS

Bile duct changes occurred in 69 (12%) of 571 sessions and 66 (17%) of 389 patients. Bile duct changes seen on CT included mild dilatation of upstream bile ducts surrounding the ablation zone in 57 patients (82.6%), biloma in the ablation zone in four patients (5.8%), and both in eight patients (11.6%). The mean time interval between radiofrequency ablation and the initial appearance of bile duct change was 1.6 months (range, immediate-9 months). Most (87%) of the 69 patients with bile duct changes showed no progression on follow-up CT, and only nine (13%) had slight progression. All patients but one, in whom cholangitis developed, had no major complications requiring specific treatment during the follow-up period.

CONCLUSION

Although bile duct changes were frequent after the radiofrequency ablation of hepatocellular carcinoma, most were of no clinical significance, and major complications requiring additional treatment were rare.

Recent advances in CT imaging of liver metastases

Multidetector computed tomography provides robust evaluation of the hepatic parenchyma. It plays a critical role in the detection of liver metastases and the assessment of treatment response to therapy. In this article, we discuss the role of multidetector computed tomography in the detection and characterization of hepatic metastases, and the value of image processing with volume rendering and maximum-intensity projection techniques in the accurate delineation of hepatic vascular anatomy and the segmental localization of lesions. This information is critical in the diagnosis and treatment of patients with metastatic disease and is essential in surgical and nonsurgical planning.

Early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma: utility of gray scale harmonic ultrasonography with a microbubble contrast agent

OBJECTIVE

To evaluate the utility of gray scale harmonic ultrasonography with a microbubble contrast agent in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.

METHODS

Seventy-five patients with 81 nodular hepatocellular carcinomas (1.3-4.8 cm) treated with percutaneous radio frequency ablation were evaluated with contrast-enhanced gray scale harmonic ultrasonography after intravenous bolus injection of a galactose-based microbubble contrast agent. The vascularity within the ablation zones was evaluated with a continuous scan for 3 to 5 seconds between 15 and 30 seconds after initiation of contrast agent injection. To evaluate the perfusion of the ablation zones, intermittent stimulated acoustic emission imaging was performed with a rapid sweeping technique from the end of the continuous scan. All patients underwent follow-up 3-phase helical computed tomography at 1 month after radio frequency ablation and were followed for at least 1 year. The results of contrast-enhanced ultrasonography were compared with those of follow-up computed tomography in terms of the presence or absence of residual unablated tumors.

RESULTS

In 10 (12%) of the 81 treated hepatocellular carcinomas, contrast-enhanced ultrasonography showed either nodular or crescentic enhancing foci at the margins of ablation zones, suggesting residual unablated tumors. Contrast-enhanced computed tomography obtained 1 month after radio frequency ablation confirmed the residual unablated tumors in the same 10 lesions. Diagnostic agreement between 1-month follow-up computed tomography and contrast-enhanced ultrasonography was achieved in all 81 cases (100%).

CONCLUSIONS

Contrast-enhanced gray scale harmonic ultrasonography can be a reliable alternative to contrast-enhanced computed tomography in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.

Hepatocellular carcinoma treated with radio-frequency ablation: spectrum of imaging findings

Contrast material-enhanced Doppler or gray-scale harmonic ultrasonography (US) may help determine the completeness or long-term therapeutic efficacy of radio-frequency (RF) ablation of hepatocellular carcinoma (HCC). Successfully treated HCC is devoid of vascularity at color or power Doppler US. When the tumor is not completely treated, residual viable tumor can be detected. These contrast-enhanced US techniques may also help identify residual tumor when performed during repeat RF ablation, when accurate localization of viable tumor is needed. To date, contrast-enhanced computed tomography (CT) has been the most widely used imaging modality in the evaluation of therapeutic response after RF ablation of HCC. At follow-up CT, successfully ablated lesions appear as low-attenuation areas with no foci of contrast enhancement either within or at the periphery of the treated lesion, whereas any foci of enhancement indicate residual or recurrent tumor. Reactive hyperemia in tissue surrounding the ablated lesion, iatrogenic arterioportal shunting, and small intralesional air pockets are frequently seen at immediate follow-up CT. Gadolinium-enhanced dynamic magnetic resonance imaging is also useful in assessing therapeutic response following RF ablation of HCC, particularly when CT findings are inconclusive. Familiarity with these imaging findings is helpful in this setting.

Magnetic resonance imaging of the liver: assessing response to treatment

Imaging plays a critical role in evaluating tumor response to treatment. Change in tumor size on cross-sectional imaging has been widely accepted and used to guide clinical decision making. Until recently, researchers used the World Health Organization (WHO) criteria to determine tumor response. A new set of criteria recently has been adopted by the WHO, the National Cancer Institute, and the European Organization for Research and Treatment of Cancer. These criteria, called the Response Evaluation Criteria in Solid Tumors (RECIST), attempt to unify response assessment of treated lesions. Magnetic resonance imaging plays an important role in evaluating treatment response to new therapies directed toward hepatic lesion treatment. In this article, we describe the new RECIST criteria and the role of magnetic resonance imaging in assessing tumor response. We also discuss the magnetic resonance imaging findings after surgical resection, liver transplantation, and tissue ablation techniques currently available for the management of patients with liver tumors.