Radiologic Monitoring of Hepatocellular Carcinoma Tumor Viability after Transhepatic Arterial Chemoembolization: Estimating the Accuracy of Contrast-enhanced Cross-sectional Imaging with Histopathologic Correlation

Diagnostic values of contrast-enhanced MRI and contrast-enhanced CT for evaluating the response of hepatocellular carcinoma after transarterial chemoembolisation: a meta-analysis

OBJECTIVES

To assess and compare the diagnostic value of contrast-enhanced MRI (CEMRI) and contrast-enhanced CT (CECT) for evaluating the response of hepatocellular carcinoma (HCC) after transarterial chemoembolisation (TACE).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase, the Cochrane Library, CNKI and Wanfang databases were systematically searched from inception to 1 August 2023.

ELIGIBILITY CRITERIA

Studies with any outcome that demonstrates the diagnostic performance of CEMRI and CECT for HCC after TACE were included.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted the data and assessed the quality of included studies. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. The diagnostic performance of CEMRI and CECT for the response of HCC was investigated by collecting true and false positives, true and false negatives, or transformed-derived data from each study to calculate specificity and sensitivity. Other outcomes are the positive likelihood ratio/negative likelihood ratio (NLR), the area under the receiver operating characteristic curve (AUC) for diagnostic tests and the diagnostic OR (DOR). Findings were summarised and synthesised qualitatively according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

This study included 5843 HCC patients diagnosed with CEMRI or CECT and treated with TACE from 36 studies. The mean proportion of men in the total sample was 76.3%. The pool sensitivity, specificity and AUC of CEMRI in diagnosing HCC after TACE were 0.92 (95% CI: 0.86 to 0.96), 0.94 (95% CI: 0.86 to 0.98) and 0.98 (95% CI: 0.96 to 0.99). The pool sensitivity, specificity and AUC of CECT in diagnosing HCC after TACE were 0.74 (95% CI: 0.68 to 0.80), 0.98 (95% CI: 0.93 to 1.00) and 0.90 (95% CI: 0.88 to 0.93).

CONCLUSIONS

In conclusion, this study found that both CEMRI and CECT had relatively high predictive power for assessing the response of HCC after TACE. Furthermore, the diagnostic value of CEMRI may be superior to CECT in terms of sensitivity, AUC, DOR and NLR.

Liver imaging reporting and data system (LI-RADS) v2018: Reliability and agreement for assessing hepatocellular carcinoma locoregional treatment response

PURPOSE

The purpose of this study was to determine the reliability and interobserver agreement of the liver imaging reporting and data system (LI-RADS) treatment response algorithm (LR-TR) v2018 using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and the added value of diffusion-weighted imaging (DWI).

MATERIALS AND METHODS

A total of 54 patients who underwent DCE-MRI and DWI after locoregional treatment of 81 hepatocellular carcinoma (HCC) lesions from September 2020 to July 2021 were included. There were 47 men and 7 women, with a mean age of 63.9 ± 9.2 (SD) years (age range: 23-77 years). Locoregional treatments included transarterial chemoembolization (TACE) (53/81; 65.4%), radiofrequency ablation (RFA) (25/81; 30.9%) and microwave ablation (MWA) (3/81; 3.7%). Two independent radiologists retrospectively evaluated DCE-MRI examinations obtained after locoregional treatment using LR-TR, and then three months later both radiologists reevaluated DCE-MRI examinations with DWI. Interobserver agreement was assessed using intraclass correlation coefficient (ICC) and Kappa test. Diagnostic performances were evaluated in term of sensitivity, specificity, and area under ROC curve (AUC) using a composite standard of reference that included results of histopathological examinations and follow-up findings.

RESULTS

Using DCE-MRI alone, observer 1 had 83.9% sensitivity (26/31; 95% confidence interval [CI]: 66-95%), 88% specificity (44/50; 95% CI: 76-95%) and 86.4% accuracy (70/81; 95%CI: 77-93%), and observer 2 had 71% sensitivity (22/31; 95% CI: 52-86%), 92% specificity (46/50; 95% CI: 81-98%) and 83.9% accuracy (68/81; 95% CI: 74-91%). For the diagnosis of viable tumors using DCE-MRI with DWI, observer 1 and observer 2 had 87.1% (27/31; 95% CI: 70-96%) and 74.2% (23/31; 95% CI: 55-88%) sensitivity, respectively. The diagnostic performance of DCE-MRI with DWI yielded an AUC (0.875; 95% CI: 0.789-0.962) not different from that of DCE-MRI without DWI (0.859; 95% CI: 0.768-0.951) (P = 0.317). Interobserver agreement for arterial phase hyperenhancement, washout, enhancement similar to pretreatment and DWI findings in all treated HCCs was almost perfect (kappa = 0.815, 0.837, 0.826 and 0.81 respectively). Agreement between observers for LR-TR category was substantial (kappa = 0.795; 95% CI: 0.665-0.924). Interobserver agreement for size of viable HCC was excellent (ICC = 0.938; 95% CI: 0.904-0.960).

CONCLUSION

LR-TR using DCE-MRI alone or DCE-MRI with DWI are both accurate for detecting viable HCC lesions after locoregional treatment, with no differences in diagnostic performance and excellent interobserver agreement.

Nomogram for predicting pathologic complete response after transarterial chemoembolization in patients with hepatocellular carcinoma

Background

The pathologic responses to transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC) are heterogeneous and result in disparate outcomes. The study aimed to establish and validate an effective nomogram for predicting pathologic complete response (PCR) after TACE.

Methods

We analyzed the clinicopathologic characteristics of HCC patients undergoing hepatectomy following TACE. Variables with statistical significance in a multivariate logistic regression analysis were incorporated in the nomogram.

Results

We detected PCR in 64 (50.4%) patients in the training cohort and 18 (37.5%) patients in the validation cohort. Univariable and multivariable logistic regression revealed that hepatitis B virus (HBV) DNA load (P=0.031), α-fetoprotein (AFP, P=0.040), maximum tumor diameter (P=0.003), preoperative TACE session (P=0.026), and modified Response Evaluation Criteria in Solid Tumors (mRECIST) complete response (P=0.030) were identified as significant predictors of PCR. Incorporating these 5 factors, a nomogram was developed which attained concordance indexes of 0.80 [95% confidence interval (CI): 0.72–0.87] and 0.82 (95% CI: 0.68–0.95) for predicting PCR in the training and validation cohorts, respectively.

Conclusions

The easy-to-use nomogram achieved a good post-TACE prediction of PCR in HCC patients. Using the model, patients who would benefit most from TACE could be identified, and the subsequent appropriate procedures could be guided accordingly.

Evaluation of Hepatocellular Carcinoma Treatment Response After Locoregional Therapy

Locoregional therapy (LRT) for hepatocellular carcinoma can be used alone or with other treatment modalities to reduce rates of progression, improve survival, or act as a bridge to cure. As the use of LRT expands, so too has the need for systems to evaluate treatment response, such as the World Health Organization and modified Response Evaluation Criteria In Solid Tumors systems and more recently, the Liver Imaging Reporting and Data System (LI-RADS) treatment response algorithm (TRA). Early validation results for LI-RADS TRA have been promising, and as research accrues, the TRA is expected to evolve in the near future.

Role of the radiologist at HCC multidisciplinary conference and use of the LR-TR algorithm for improving workflow

Multidisciplinary conferences (MDCs) play a major role in management and care of oncology patients. Hepatocellular carcinoma (HCC) is a complex disease benefiting from multidisciplinary discussions to determine optimal patient management. A multitude of liver-directed locoregional therapies have emerged allowing for more options for treatment of HCC. A radiologist dedicated to HCC-MDC is an important member of the team contributing to patient care in multiple ways. The radiologist plays a key role in image interpretation guiding initial therapy discussions as well as interpreting post-treatment imaging following liver-directed therapy. Standardization of image interpretation can lead to more consistent treatment received by the patient as well as accurate assessment of transplant eligibility. The radiologist can facilitate this process using structured reporting that is also supported by stakeholders involved in interdisciplinary management of liver diseases. The Liver Imaging Reporting and Data System (LI-RADS), is a living document which offers a standardized reporting algorithm for consistent communication of radiologic findings for HCC screening and characterization of liver observations in patients at risk for HCC. The LI-RADS post-treatment algorithm (LR-TR algorithm) has been developed to standardize liver observations following liver-directed locoregional therapy. This review article focuses on the role of the radiologist at HCC-MDC and implementation of the LR-TR algorithm for improving workflow.

Evaluation of LI-RADS Version 2018 Treatment Response Algorithm for Hepatocellular Carcinoma in Liver Transplant Candidates: Intraindividual Comparison between CT and Hepatobiliary Agent-enhanced MRI

Background The Liver Imaging Reporting and Data System (LI-RADS), version 2018, treatment response algorithm (TRA) is used to assess hepatocellular carcinoma (HCC) after local-regional therapy (LRT). However, its diagnostic performance has not yet been fully compared between CT and hepatobiliary agent (HBA)-enhanced MRI in patients who have undergone liver transplant (LT). Purpose To compare the diagnostic performance of LI-RADS TRA when using CT versus using HBA-enhanced MRI in an intraindividual manner according to pathologic results. Materials and Methods Between January 2011 and September 2019, 165 patients with 237 clinically suspected HCCs underwent LRT followed by LT and were retrospectively included. All patients underwent both CT and HBA-enhanced MRI after LRT and before LT. Three radiologists independently assessed tumor viability with both modalities by using LI-RADS TRA and reached a consensus. Pathologic tumor viability categorized as either completely (100%) or incompletely (<100%) necrotic obtained from the explanted liver served as the reference standard. Sensitivity and specificity of the LI-RADS TRA in the consensus reading were then compared between CT and HBA-enhanced MRI by using the ratio estimator approach. Interobserver agreements were calculated by using Fleiss κ statistics. Results There were 165 patients (mean age, 62 years ± 9 [standard deviation]; 135 men) with a total of 237 lesions, of which 107 were viable tumors (45.1%) at pathologic evaluation. With the LI-RADS TRA, sensitivity and specificity of the viable category for detection of viable HCCs at pathologic evaluation were 42.1% (45 of 107 lesions) and 95.4% (124 of 130 lesions) with CT and 52.3% (56 of 107 lesions) and 93.9% (122 of 130 lesions) with HBA-enhanced MRI, with a significant difference in sensitivity but not specificity (P = .009 and P = .42, respectively). Interobserver agreements for the LI-RADS TRA were substantial for both CT and HBA-enhanced MRI (κ, 0.69 for both). Conclusion In patients who underwent local-regional therapy for hepatocellular carcinoma before liver transplant, hepatobiliary agent-enhanced MRI was more sensitive than CT in evaluating tumor viability with the Liver Imaging Reporting and Data System, version 2018, treatment response algorithm. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Bashir and Mendiratta-Lala in this issue.

Interreader Reliability of Liver Imaging Reporting and Data System Treatment Response: A Systematic Review and Meta-Analysis

BACKGROUND

For a proper management strategy in patients with locoregionally treated hepatocellular carcinoma (HCC), it is essential that the Liver Imaging Reporting and Data System (LI-RADS) treatment response algorithm (LR-TR) has high interreader reliability. We aimed to systematically evaluate the interreader reliability of LR-TR and sources of any study heterogeneity.

METHODS

Original studies reporting the interreader reliability of LR-TR were identified in MEDLINE and EMBASE up to 20 September 2020. The pooled kappa coefficient (κ) was calculated using the DerSimonian-Laird random effects model. Subgroup analyses were performed according to imaging modality (magnetic resonance imaging (MRI) or computed tomography (CT)). Meta-regression analyses were performed to explore study heterogeneity.

RESULTS

Eight studies with 851 HCCs were finally included. Pooled κ was 0.70 (95% CI, 0.58-0.82) for CT/MRI LR-TR, and those of MRI and CT were 0.71 (95% CI, 0.53-0.89) and 0.71 (95% CI, 0.65-0.78), respectively. Study design (p < 0.001) and type of treatment (p = 0.02) were significantly associated with substantial study heterogeneity.

CONCLUSION

LR-TR showed substantial interreader reliability regardless of the imaging modality. Because of substantial study heterogeneity, which was significantly associated with study design and type of treatment, published values for the interreader reliability of LR-TR should be interpreted with care.

Added Value of CT Arterial Subtraction Images in Liver Imaging Reporting and Data System Treatment Response Categorization for Transcatheter Arterial Chemoembolization-Treated Hepatocellular Carcinoma

OBJECTIVES

The aim of this study was to assess the benefit of adding arterial subtraction images from computed tomography (CT) to the Liver Imaging Reporting and Data System (LI-RADS) v2018 treatment response (LR-TR) categorization in patients treated with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This retrospective study included 115 patients with 151 HCCs treated by TACE using an emulsion of doxorubicin and iodized oil who underwent multiphasic CT protocol that additionally generated arterial subtraction images based on nonrigid anatomic correction algorithm. Of 151 HCCs, 67 (44.4%) were viable and 84 (55.6%) were nonviable. Two independent readers assessed the per-lesion LR-TR categories in set 1 of multiphasic CT images alone and set 2 including both set 1 and CT arterial subtraction images, besides diagnostic confidence, and the quality of subtraction images. The sensitivity and specificity of LR-TR viable category between the sets were compared using the generalized estimating equation. Interobserver agreements of LR-TR categorization in each set and the quality of subtraction images were assessed by Cohen κ.

RESULTS

The quality of subtraction images was mostly good to perfect (98.7%) with good interobserver agreement (κ = 0.71), and none were nondiagnostic. For detecting viable HCC, LR-TR viable category showed sensitivity of 53.7% to 56.7% and specificity of 96.4% to 98.8% in set 1. In comparison, set 2 showed significantly higher sensitivity of 88.1% to 89.6% (P < 0.002) and equivalent specificity of 94% to 95.2% (P > 0.13) for the same category. In sets 1 and 2, 31.3% to 34.3% and 9% to 10.4% of viable HCC were miscategorized as LR-TR nonviable, respectively. LR-TR equivocal category was less assigned in set 2 (1.3%) than in set 1 (6.6%-7.9%). Set 2 showed slightly higher level of confidence for LR-TR categorization compared with set 1 (3.4 ± 0.8 vs 3.8 ± 0.5). Interobserver agreement was excellent in both sets (κ = 0.85 in set 1 and 0.97 in set 2).

CONCLUSIONS

The LR-TR viable category is highly specific but inadequately sensitive for detecting viable tumor in TACE-treated HCC on conventional multiphasic CT. Adding arterial subtraction images to the conventional CT images significantly increases sensitivity without compromising the specificity and improves the diagnostic confidence of LR-TR viable category.

Evaluation of liver tumour response by imaging

The goal of assessing tumour response on imaging is to identify patients who are likely to benefit - or not - from anticancer treatment, especially in relation to survival. The World Health Organization was the first to develop assessment criteria. This early score, which assessed tumour burden by standardising lesion size measurements, laid the groundwork for many of the criteria that followed. This was then improved by the Response Evaluation Criteria in Solid Tumours (RECIST) which was quickly adopted by the oncology community. At the same time, many interventional oncology treatments were developed to target specific features of liver tumours that result in significant changes in tumours but have little effect on tumour size. New criteria focusing on the viable part of tumours were therefore designed to provide more appropriate feedback to guide patient management. Targeted therapy has resulted in a breakthrough that challenges conventional response criteria due to the non-linear relationship between response and tumour size, requiring the development of methods that emphasize the appearance of tumours. More recently, research into functional and quantitative imaging has created new opportunities in liver imaging. These results have suggested that certain parameters could serve as early predictors of response or could predict later tumour response at baseline. These approaches have now been extended by machine learning and deep learning. This clinical review focuses on the progress made in the evaluation of liver tumours on imaging, discussing the rationale for this approach, addressing challenges and controversies in the field, and suggesting possible future developments.

Utility of Contrast-Enhanced Ultrasound for Early Therapeutic Evaluation of Hepatocellular Carcinoma After Transcatheter Arterial Chemoembolization

OBJECTIVES

We aimed to investigate whether contrast-enhanced ultrasound (CEUS) could be useful for early evaluation of the treatment response to transcatheter arterial chemoembolization (TACE) of hepatocellular carcinoma (HCC).

METHODS

This study retrospectively selected HCCs in which homogeneous retention of iodized oil was confirmed on non-contrast-enhanced computed tomography performed immediately after TACE. Therapeutic responses of HCCs were evaluated by CEUS 1 to 2 days after TACE and by contrast-enhanced computed tomography (CECT) approximately 4 weeks after TACE. We investigated the noninferiority of CEUS 1 to 2 days after TACE to CECT approximately 4 weeks after TACE in terms of the diagnostic accuracy of the therapeutic response to TACE on HCC.

RESULTS

Eighty-nine HCCs were enrolled in this study between April 2014 and June 2016. A complete response was observed in 57 of 89 nodules (64.0%), and an incomplete response was observed in the remaining 32 nodules (36.0%). The accuracy rates for CEUS 1 to 2 days after TACE and CECT approximately 4 weeks after TACE in the therapeutic effect of TACE on HCCs were 83.1% (95% confidence interval, 73.7%-90.2%) and 83.1% (95% confidence interval, 73.7%-90.2%), respectively. The difference in diagnostic accuracy between methods was 0%, which was below the predetermined noninferiority limit of 15%, and CEUS 1 to 2 days after TACE was noninferior to CECT approximately 4 weeks after TACE.

CONCLUSIONS

Our results suggest that CEUS is a useful modality for early therapeutic evaluation of TACE for HCC, and we can thus plan the next treatment strategies for HCC within a few days after TACE.

Lipiodol retention pattern after TACE for HCC is a predictor for local progression in lesions with complete response

Background

To evaluate the predictive value of the lipiodol retention pattern for local progression of HCC with a complete response (CR) on CT according to mRECIST criteria after a first session of conventional chemoembolization (cTACE).

Methods

From January 2014 to May 2016 all consecutive patients undergoing a first cTACE session for HCC were identified. Inclusion criteria were the presence of ≤3 HCCs and available pre- and post-cTACE CT. Tumor response was classified according to mRECIST criteria. The analysis focused on tumors with a CR. The lipiodol retention pattern in these tumors was classified as complete (C-Lip, covering the entire tumor volume), or incomplete (I-Lip). Local progression was defined as the reappearance of areas of enhancement on arterial-phase images with washout on portal/delayed phase images within 2 cm from treated tumors on follow-up CT.

Results

The final population included 50 patients with 82 HCCs. A total of 46 (56%) HCCs were classified with a CR, including 16 (35%) with I-Lip, and 30 (65%) with C-Lip. After a median follow-up of 14 months (3.2–35.9 months), 15/16 (94%) and 10/30 (30%) of I-Lip and C-Lip HCCs showed local progression on CT, respectively (p < 0.001), with no significant difference in the time to progression (mean 11.1 ± 2 vs. 13.4 ± 3 months for I-Lip and C-Lip, respectively p = 0.51).

Conclusions

HCCs with incomplete lipiodol retention after a first cTACE session have a high risk of local progression even when there is a CR according to mRECIST, and should be considered to be incompletely treated.

Evaluation of treatment response in hepatocellular carcinoma in the explanted liver with Liver Imaging Reporting and Data System version 2017

OBJECTIVE

To investigate the performance of Liver Imaging Reporting and Data System (LI-RADS) v2017 treatment response algorithm for predicting hepatocellular carcinoma (HCC) viability after locoregional therapy (LRT) using the liver explant as reference.

METHODS

One hundred fourteen patients with 206 HCCs who underwent liver transplantation (LT) after LRT for HCCs were included in this retrospective study. Two radiologists independently evaluated tumor viability using the LI-RADS and modified RECIST (mRECIST) with CT and MRI, respectively. The sensitivity and specificity of arterial phase hyperenhancement (APHE) and LR-TR viable criteria (any of three findings: APHE, washout, and enhancement pattern similar to pretreatment imaging) were compared using logistic regression. Receiver operating characteristics (ROC) analysis was used to compare the diagnostic performance between LI-RADS and mRECIST and between CT and MRI.

RESULTS

The sensitivity and specificity for diagnosing viable tumor were not significantly different between APHE alone and LR-TR viable criteria on CT (p = 0.054 and p = 0.317) and MRI (p = 0.093 and p = 0.603). On CT, the area under the ROC curve (AUC) of LI-RADS was significantly higher than that of mRECIST (0.733 vs. 0.657, p < 0.001). On MRI, there was no significant difference in AUCs between LI-RADS and mRECIST (0.802 vs. 0.791, p = 0.500). Intra-individual comparison of CT and MRI showed comparable AUCs using LI-RADS (0.783 vs. 0.795, p = 0.776).

CONCLUSIONS

LI-RADS v2017 treatment response algorithm showed better diagnostic performance than mRECIST on CT. With LI-RADS, CT and MRI were comparable to diagnose tumor viability of HCC after LRT.

KEY POINTS

• Using Liver Imaging Reporting and Data System (LI-RADS) v2017 treatment response algorithm, the viability of hepatocellular carcinoma (HCC) after locoregional therapy (LRT) can be accurately diagnosed. • LI-RADS v2017 treatment response algorithm is superior to modified Response Evaluation Criteria in Solid Tumors for evaluating HCC viability using CT. • Either CT or MRI can be performed to assess tumor viability after LRT using LI-RADS v2017 treatment response algorithm.

Assessment of the response of hepatocellular carcinoma to interventional radiology treatments

According to Barcelona Clinic Liver Cancer (BCLC) guidelines, interventional radiology procedures are valuable treatment options for many hepatocellular carcinomas (HCCs) that are not amenable to resection or transplantation. Accurate assessment of the efficacy of therapies at earlier stages enables completion of treatment, optimal follow-up and to prevent potentially unnecessary treatments, side effects and costly failure. The goal of this review is to summarize and describe the radiological strategies that have been proposed to predict survival and to stratify HCC responses after interventional radiology therapies. New techniques currently in development are also described.

MRI assessment of hepatocellular carcinoma after locoregional therapy

Liver cirrhosis and hepatocellular carcinoma (HCC) constitute one of the major causes of morbidity, mortality, and high health care costs worldwide. Multiple treatment options are available for HCC depending on the clinical status of the patient, size and location of the tumor, and available techniques and expertise. Locoregional treatment options are multiple. The most challenging part is how to assess the treatment response by different imaging modalities, but our scope will be assessing the response to locoregional therapy for HCC by MRI. This will be addressed by conventional MR methods using LI-RADS v2018 and by functional MR using diffusion-weighted imaging, perfusion, and highlighting the value of the novel intravoxel incoherent motion (IVIM).

Parametric response mapping cut-off values that predict survival of hepatocellular carcinoma patients after TACE

PURPOSE

Parametric response mapping (PRM) is a novel image-analysis technique applicable to assess tumor viability and predict intrahepatic recurrence of hepatocellular carcinoma (HCC) patients treated with transarterial chemoembolization (TACE). However, to date, the prognostic value of PRM for prediction of overall survival in HCC patients undergoing TACE is unclear. The objective of this explorative, single-center study was to identify cut-off values for voxel-specific PRM parameters that predict the post TACE overall survival in HCC patients.

METHODS

PRM was applied to biphasic CT data obtained at baseline and following 3 TACE treatments of 20 patients with HCC tumors ≥ 2 cm. The individual portal venous phases were registered to the arterial phases followed by segmentation of the largest lesion, i.e., the region of interest (ROI). Segmented voxels with their respective arterial and portal venous phase density values were displayed as a scatter plot. Voxel-specific PRM parameters were calculated and compared to patients' survival at 1, 2, and 3 years post treatment to identify the maximal predictive parameters.

RESULTS

The hypervascularized tissue portion of the ROI was found to represent an independent predictor of the post TACE overall survival. For this parameter, cut-off values of 3650, 2057, and 2057 voxels, respectively, were determined to be optimal to predict overall survival at 1, 2, and 3 years after TACE. Using these cut points, patients were correctly classified as having died with a sensitivity of 80, 92, and 86% and as still being alive with a specificity of 60, 75, and 83%, respectively. The prognostic accuracy measured by area under the curve (AUC) values ranged from 0.73 to 0.87.

CONCLUSION

PRM may have prognostic value to predict post TACE overall survival in HCC patients.

Locoregional therapies for hepatocellular carcinoma and the new LI-RADS treatment response algorithm

Radiologists play a central role in the assessment of patient response to locoregional therapies for hepatocellular carcinoma (HCC). The identification of viable tumor following treatment guides further management and potentially affects transplantation eligibility. Liver Imaging Reporting and Data Systems (LI-RADS) first introduced the concept of LR-treated in 2014, and a new treatment response algorithm is included in the 2017 update to assist radiologists in image interpretation of HCC after locoregional therapy. In addition to offering imaging criteria for viable and nonviable HCC, new concepts of nonevaluable tumors as well as tumors with equivocal viability are introduced. Existing guidelines provided by response evaluation criteria in solid tumors (RECIST) and modified RECIST address patient-level assessments and are routinely used in clinical trials but do not address the variable appearances following different locoregional therapies. The new LI-RADS treatment response algorithm addresses this gap and offers a comprehensive approach to assess treatment response for individual lesions after a variety of locoregional therapies, using either contrast-enhanced CT or MRI.

Parametric response mapping of dynamic CT: enhanced prediction of survival in hepatocellular carcinoma patients treated with transarterial chemoembolization

PURPOSE

The aim of this study was to evaluate the prognostic significance of parametric response mapping (PRM) analysis for hepatocellular carcinoma (HCC) patients undergoing transarterial chemoembolization (TACE).

METHODS

We recruited 65 HCC patients who underwent TACE. These patients underwent longitudinal multiphasic CT before and after TACE. We applied PRM analysis to the baseline CT before TACE and first/second follow-up CTs. The results of PRM analyses were used to stratify patients into responders and non-responders. Overall survival was compared between the two groups. An independent survival analysis using conventional radiological assessments was performed, and the results were compared with PRM results. Univariate and multivariate analyses were performed to identify clinical factors affecting survival.

RESULTS

The PRM analyses demonstrated that the responding group had a median survival of 529 days, while the non-responding group had a median survival of 263 days [hazard ratio (HR) 12.9, p < 0.05 for differences in survival]. The manual analyses indicated median survivals of 491 and 329 days for the responding and non-responding groups, respectively (HR 2.7, p < 0.05). Tumor size, albumin level, and PRM values were found to be significantly related to overall survival after univariate and multivariate analyses.

CONCLUSIONS

The PRM analysis could be a better predictor of overall survival for patients with HCC undergoing TACE than conventional radiological assessments.

Imaging prediction of residual hepatocellular carcinoma after locoregional therapy in patients undergoing liver transplantation or partial hepatectomy

PURPOSE

Locoregional therapies for hepatocellular carcinoma (HCC) offer alternatives for patients unable to undergo resection or awaiting transplant. We sought to evaluate the prevalence and interobserver agreement of imaging features suggestive of viable tumor at posttherapy CT/MRI and to determine a size threshold for tumor detection.

METHODS

Patients having undergone liver transplant or hepatectomy between 2012 and 2014 with presurgical embolization or ablation of HCC were identified. Imaging was retrospectively reviewed, and enhancement characteristics of each lesion were noted by two radiologists. Original pathology slides were reviewed, and the size of nodular viable tumor was noted, if present. Cohen's kappa was used to evaluate interobserver agreement.

RESULTS

87 patients with 129 HCCs were reviewed retrospectively following IRB approval. 50% (65/129) of lesions showed viable tumor at pathology. 86 lesions (67%) were imaged with CT and 43 (33%) with MR. Of viable lesions, 25 (38%) showed nodular arterial enhancement and 18 (28%) demonstrated washout. One lesion had capsule appearance. Sensitivity/specificity for nodular enhancement, washout, and capsule were 0.38/0.83, 0.28/0.89, and 0.02/1.00, respectively. Overall detection rate was 41% of <1 cm, 54% of 1-2 cm, and 57% of >2 cm viable lesions.

CONCLUSIONS

Nodular arterial enhancement was most frequently observed, followed by washout. Both showed moderate interobserver agreement. Sensitivity of any imaging feature was less than 50%, though findings were specific for viable disease. There is limited detection of nodules of viable tumor <1 cm and only marginal detection of larger lesions, though MRI outperformed CT for the detection of subcentimeter viable tumor.

Evaluation of tumor recurrence after superselective conventional transcatheter arterial chemoembolization for hepatocellular carcinoma: Comparison of computed tomography and gadoxetate disodium-enhanced magnetic resonance imaging

AIM

To retrospectively evaluate the detectability of tumor recurrence with computed tomography (CT) and magnetic resonance imaging (MRI) after superselective conventional transcatheter arterial chemoembolization (cTACE) for hepatocellular carcinoma (HCC).

METHODS

The detectability of tumor recurrence with CT and gadoxetate disodium-enhanced MRI obtained within 30 days (mean, 16.9 ± 10.1) were compared in 38 patients with recurrent HCC after superselective cTACE. Tumor recurrence was divided into local and distant recurrence. Local recurrence was also divided into intratumoral and peritumoral recurrence.

RESULTS

Tumor recurrence (maximum diameter, 19.7 ± 10.1 mm) was demonstrated by images 12.4 ± 11.7 months after cTACE. CT could depict 16 (76.2%) of 21 intratumoral recurrences in 12 patients and 14 (53.8%) of 26 peritumoral recurrences in 11, as well as 39 (55.7%) of 70 distant recurrences in 15 (75%) of 20 patients. Arterial phase MRI could depict 20 (95.2%) of 21 intratumoral recurrences in 14 patients and all 26 (100%) peritumoral recurrences in 21, as well as 60 (85.7%) distant recurrences in all 20 (100%) patients. The detectability of tumor recurrence with MRI was significantly higher than that with CT (P = 0.00549). On MRI, pseudolesions were observed in five (13.2%) patients and artifacts in the arterial phase in five (13.2%). Regarding the diagnostic performance, CT was superior to MRI in two (5.3%) patients and MRI was superior to CT in 19 (50%). They were almost equal in 17 (44.7%).

CONCLUSION

The detectability of tumor recurrence after superselective cTACE with gadoxetate disodium-enhanced MRI was superior to that of CT.

PET/Computed Tomography in Evaluation of Transarterial Chemoembolization

Transarterial chemoembolization is a minimally invasive procedure that deprives the tumor of its blood supply, and is especially used for the treatment of unresectable hepatocellular carcinoma. Metabolic evaluation of interventional therapies such as transarterial chemoembolization in hepatocellular carcinoma is proving to be a valuable tool in choosing therapies that are better targeted to patients, especially because of its likely contribution in predicting treatment response in unresectable lesions after these therapies.

Parametric response mapping of dynamic CT for predicting intrahepatic recurrence of hepatocellular carcinoma after conventional transcatheter arterial chemoembolization

OBJECTIVES

The aim of our study was to determine the diagnostic value of a novel image analysis method called parametric response mapping (PRM) for prediction of intrahepatic recurrence of hepatocellular carcinoma (HCC) treated with conventional transcatheter arterial chemoembolization (TACE).

METHODS

This retrospective study was approved by the IRB. We recruited 55 HCC patients who achieved complete remission (CR) after TACE and received longitudinal multiphasic liver computed tomography (CT). The patients fell into two groups: the recurrent tumour group (n = 29) and the non-recurrent tumour group (n = 26). We applied the PRM analysis to see if this technique could distinguish between the two groups. The results of the PRM analysis were incorporated into a prediction algorithm. We retrospectively removed data from the last time point and attempted to predict the response to therapy of the removed data.

RESULTS

The PRM analysis was able to distinguish between the non-recurrent and recurrent groups successfully. The prediction algorithm detected response to therapy with an area under the curve (AUC) of 0.76, while the manual approach had AUC 0.64.

CONCLUSIONS

Adopting PRM analysis can potentially distinguish between recurrent and non-recurrent HCCs and allow for prediction of response to therapy after TACE.

KEY POINTS

Parametric response mapping (PRM) could help assess patients with recurrent HCCs after TACE. Parametric response mapping could direct patients to individualized therapy. Longitudinal CT images were analyzed with advanced image analysis method.

Histologic study of the effects of chemoembolization with preloaded doxorubicin beads in patients with hepatocellular carcinoma

OBJECTIVE

To determine the degree of tumor necrosis in surgical specimens of hepatocellular carcinomas treated with microspheres preloaded with doxorubicin and to analyze the relationship between the degree of necrosis and a) morphologic factors and b) imaging biomarkers.

MATERIAL AND METHODS

We studied the livers of 21 patients who had undergone selective arterial chemoembolization with DC beads (Biocompatibles, UK) before receiving liver transplants.

RESULTS

Imaging techniques detected 43 nodules (mean size, 25 mm). Angiography showed 25 hypervascularized nodules, 12 slightly vascularized nodules, and 6 avascular nodules. A total of 81 hepatocellular carcinomas (mean size, 15 mm) were detected in the specimens: two were capsular and two had vascular infiltration. The mean degree of necrosis after chemoembolization was 39%; necrosis was greater than 60% in 28 hepatocellular carcinomas and less than 60% in 52. The degree of necrosis correlated significantly with the time elapsed between the last chemoembolization treatment and liver transplantation (the degree of necrosis decreased as time increased), with the number of nodules in the specimen, and with capsular infiltration. When imaging techniques detected 1 or 2 nodules, there was a greater probability of achieving greater than 90% necrosis. No relation with the degree of necrosis achieved was found for the size of the nodules detected at imaging, the enhancement pattern, or the number of chemoembolization treatments.

CONCLUSION

The degree of necrosis achieved depends on the time spent on the waiting list, on the number of nodules in the specimen, and on whether capsular infiltration is present.

Value of 18F-FDG PET/CT in detecting viable tumour and predicting prognosis of hepatocellular carcinoma after TACE

AIM

To evaluate the efficacy of combined PET/CT in the detection of viable tumour in patients with hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE). The correlation between 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) uptake during PET and prognosis was evaluated.

MATERIALS AND METHODS

Seventy-three patients with 91 HCCs who had undergone TACE with lipiodol before (18)F-FDG PET/CT were retrospectively reviewed. The pattern of lipiodol deposition in the tumour was divided into three groups: grade I, lipiodol remaining in ≥60% of the tumour; grade II, 20-60%; and grade III, ≤20%. The performance of (18)F-FDG PET/CT in evaluating the viability of HCC was assessed and compared with that of contrast-enhanced CT (CECT). The predictive value of maximal tumoural standardized uptake value (SUV) to mean liver SUV (TSUVmax/LSUVmean) ratio was tested.

RESULTS

Comparing the receiver-operating characteristic area, (18)F-FDG-PET/CT was found to be superior to CECT for the detection of viable tumour in patients with HCC after TACE (p = 0.04). A high SUV ratio (TSUVmax/LSUVmean ≥1.65) correlated significantly with tumour size (p = 0.0096), the grade of lipiodol deposition (p = 0.0387) and serum α-foetoprotein (AFP) level (p = 0.0142), but did not correlate with pathological grade (p = 0.2626). The overall survival rate was significantly higher in the low SUV ratio (TSUVmax/LSUVmean<1.65) group (p = 0.024).

CONCLUSION

(18)F-FDG-PET/CT is efficient in assessing the viability of HCC after TACE and is superior to CECT in grades I and II, and similar in grade III. It provides valuable information for prediction of prognosis and may aid decisions regarding treatment strategy.

Response stratification and survival analysis of hepatocellular carcinoma patients treated with intra-arterial therapy using MR imaging-based arterial enhancement fraction

PURPOSE

To investigate the feasibility that arterial enhancement fraction (AEF) is associated with response of hepatocellular carcinoma (HCC) following intra-arterial therapy (IAT) and to compare AEF response with currently used tumor response metrics.

MATERIALS AND METHODS

The AEF, Response Evaluation Criteria in Solid Tumors (RECIST), modified RECIST (mRECIST), and European Association for the Study of the Liver (EASL) of the largest treated index lesion and AEF of the tumor-free hepatic parenchyma was measured on representative axial images in 131 patients (108 male; mean age, 61.9 years). Clinical measures and patient survival were assessed. Statistical analysis included Wilcoxon signed-rank test and the COX proportional hazards model.

RESULTS

After IAT, the mean AEF of the tumor decreased by 22% (66.7-44.8%, P < 0.0001), while the mean AEF of the tumor-free parenchyma remained unchanged (27.2-26.5%, P = 0.50). Median survival of all 131 patients with liver cancer was 17 months. Patients were stratified into AEF-responders if they had an AEF-decrease ≥35% (AEF-responders: n = 67; AEF-nonresponders: n = 64). AEF-responders survived longer than nonresponders (34.8 months versus 10.8 months, hazard ratio = 0.39; P < 0.0001). Responders according to RECIST, mRECIST, or EASL did not survive significantly longer compared with nonresponders.

CONCLUSION

Evaluating the AEF values based on tri-phasic MRI is associated with tumor response in patients with unresectable HCC treated with IAT.

Position paper of the Italian Association for the Study of the Liver (AISF): the multidisciplinary clinical approach to hepatocellular carcinoma

Patients with hepatocellular carcinoma should be managed with a multidisciplinary approach framed in a network where all the diagnostic techniques and therapeutic resources are available in order to provide the optimal level of care. Given this assumption, the Coordinating Committee of the Italian Association for the Study of the Liver nominated a panel of experts to elaborate practical recommendations for the multidisciplinary management of hepatocellular carcinoma aiming to provide: (1) homogeneous and efficacious diagnostic and staging work-up, and (2) the best treatment choice tailored to patient status and tumour stage at diagnosis. The 2010 updated American Association for the Study of Liver Disease Guidelines for hepatocellular carcinoma were selected as the reference document. For each management issue, the American Association for the Study of Liver Disease recommendations were briefly summarised and discussed, according to both the scientific evidence published after their release and the clinical expertise of the Italian centres taking care of these patients. The Italian Association for the Study of the Liver expert panel recommendations are finally reported.

Imaging appearance of treated hepatocellular carcinoma

Surgical resection and imaging guided treatments play a crucial role in the management of hepatocellular carcinoma (HCC). Although the primary end point of treatment of HCC is survival, radiological response could be a surrogate end point of survival, and has a key role in HCC decision-making process. However, radiological assessment of HCC treatment efficacy is often controversial. There are few doubts on the evaluation of surgical resection; in fact, all known tumor sites should be removed. However, an unenhancing partial linear peripheral halo, in most cases, surrounding a fluid collection reducing in size during follow-up is demonstrated in successfully resected tumor with bipolar radiofrequency electrosurgical device. Efficacy assessment of locoregional therapies is more controversial and differs between percutaneous ablation (e.g., radiofrequency ablation and percutaneous ethanol injection) and transarterial treatments (e.g., conventional transarterial chemoembolization, transarterial chemoembolization with drug eluting beads and radioembolization). Finally, a different approach should be used for new systemic agent that, though not reducing tumor mass, could have a benefit on survival by delaying tumor progression and death. The purpose of this brief article is to review HCC imaging appearance after treatment.

Radiology estimates of viable tumor percentage in hepatocellular carcinoma ablation cavities correlate poorly with pathology assessment

CONTEXT

No study has evaluated radiology/pathology correlation of percentage viable tumor (PVT) estimates in ablated hepatocellular carcinoma (HCC) to examine the reliability of radiologic estimates.

OBJECTIVE

To determine how well interdisciplinary PVT estimates correlate and identify pathologic factors that influence this correlation.

DESIGN

Pathologists and radiologists established blinded PVT estimates in 22 HCC ablation cavities. Paired sample t tests examined the differences between the interdisciplinary estimates.

RESULTS

Fifteen cavities had pathologic viable tumor (VT) (68%) and 6 had radiographic VT (22%). Radiology's sensitivity for detecting VT was 40% and the specificity was 100%. Pathology detected significantly more VT than radiology (pathology mean = 22.3% versus radiology mean = 2.6%; P = .005). Five cavities had tumor growth in a discontinuous rim pattern, 7 in a nodular pattern, and 3 in a solid pattern. Radiology did not detect VT in cavities with a discontinuous rim pattern (sensitivity = 0%) but did detect VT in 3 cavities with a nodular pattern (sensitivity = 43%), and in all cavities with a solid pattern (sensitivity = 100%). There was no significant difference in PVT estimates in cavities 3.5 cm or larger (P = .07), but there was a significant difference in cavities smaller than 3.5 cm (P = .01).

CONCLUSION

This study clarifies that the risk of underestimation by imaging is greatest in small lesions (<3.5 cm), though the sensitivity of detection depends primarily on the tumor growth pattern within the cavity. This underestimation raises the question of whether basing treatment decisions on a radiologic impression of complete ablation is valid.

Hepatocellular carcinoma responding to superselective transarterial chemoembolization: an issue of nodule dimension?

PURPOSE

To evaluate the per-nodule efficacy of superselective transarterial chemoembolization of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

From 2006-2009, 271 cirrhotic patients with 635 nodules underwent a first superselective transarterial chemoembolization, repeated "on demand" after local recurrences (LR) or partial responses (PR). Complete response (CR), time to nodule progression (TTnP), and local recurrence rate (LRR), according to three size classes (≤ 2 cm, 2.1-5 cm, and>5 cm) were evaluated.

RESULTS

After the first superselective transarterial chemoembolization, the CR was 64%, sustained over time in 77%, higher in small (68%) and intermediate-size (64%) nodules than in large nodules (25%; P<.001). The LRR was 23%:20% in small, 27% in intermediate, and 67% in large HCCs (P<.05). The median TTnP of large HCCs was 4 months versus 7-9 months for small and intermediate HCCs. The second superselective transarterial chemoembolization achieved a higher CR (63% in LR, 52% in PR) than the third superselective transarterial chemoembolization (32%). Median TTnP after the second superselective transarterial chemoembolization for LR and PR (8 months and 6 months) was longer than after the third superselective transarterial chemoembolization (3.5 months). Nodules ≤ 5 cm had a CR after the first superselective transarterial chemoembolization (66%) and the second superselective transarterial chemoembolization for LR (64%) or PR (55%) higher than after the third superselective transarterial chemoembolization (40%); nodules>5 cm had a CR of 25% after the first superselective transarterial chemoembolization, LR of 50% and PR of 25%, and after the second and third superselective transarterial chemoembolizations, PR of 0%.

CONCLUSIONS

Effectiveness of superselective transarterial chemoembolization has a clear cutoff above and below 5-cm nodules, with better results in smaller nodules. In HCCs ≤ 5 cm, the efficacy of the first and second superselective transarterial chemoembolizations performed for LR was higher than the second superselective transarterial chemoembolization for PR and the third superselective transarterial chemoembolization. For HCCs>5 cm, retreatment of PR is of little value, and the third cycle is ineffective.

Optimal measurement modality and method for evaluation of responses to transarterial chemoembolization of hepatocellular carcinoma based on enhancement criteria

PURPOSE

To determine the usefulness of enhancement by iodized oil deposits on computed tomography (CT) following transarterial chemoembolization for hepatocellular carcinoma (HCC), and to compare the reliability of such CT imaging with that of magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Fifty-one patients for whom resected or explanted livers containing chemoembolized HCC lesions of at least 1 cm were available. Imaging responses were determined based on modified Response Evaluation Criteria In Solid Tumors (mRECIST) and European Association for the Study of the Liver (EASL) criteria for 59 target tumors on CT and MR scans before surgery. CT-based evaluation was performed per mRECIST and EASL criteria, considering iodized oil retention as indicating necrosis and, alternatively, as enhancing viable tissue ("mRECIST-Lipiodol" and "EASL-Lipiodol"). Pathologic necrosis was graded as 100%, 50%-99%, or less than 50%.

RESULTS

Goodman-Kruskal γ-values for radiologic-pathologic correlation were greater than 0.95 for mRECIST and EASL criteria on CT or MR imaging. However, mRECIST-Lipiodol and EASL-Lipiodol measurements showed weaker correlation with pathologic findings, with γ-values of 0.797 and 0.846, respectively. With respect to intermethod agreement, weighted γ-values for mRECIST by CT and MR, and for EASL criteria by CT and MR, both exceeded 0.80, whereas mRECIST-Lipiodol and EASL-Lipiodol showed only moderate levels of agreement with mRECIST/EASL criteria by CT or MR imaging, with γ-values of 0.522-0.631.

CONCLUSIONS

Response estimation based on measurement of iodized oil deposits as necrosis on CT when applying enhancement criteria after chemoembolization for HCC correlated well with actual pathologic class, and agreed with MR-based evaluation.

Enhancement patterns of hepatocellular carcinoma after transarterial chemoembolization using drug-eluting beads on arterial phase CT images: a pilot retrospective study

OBJECTIVE

The purpose of this article is to assess CT enhancement patterns of hepatocellular carcinoma (HCC) within 1 month after transarterial chemoembolization (TACE) using drug-eluting beads and to determine whether enhancement patterns may be useful for predicting local tumor progression.

MATERIALS AND METHODS

Forty-one patients with 50 HCCs underwent CT within 1 month after TACE with drug-eluting beads. Two blinded readers independently reviewed the arterial phase images and classified enhancement patterns as follows: no enhancement, peripheral ring enhancement, and peripheral nodulelike enhancement. Enhancement patterns were correlated with time to tumor progression of enhancing tissue by log-rank test.

RESULTS

In the group with no enhancement, 92.3% (24/26) had not progressed and 7.7% (2/26) showed progression; for peripheral ring enhancement, 83.3% (10/12) had not progressed and 16.7% (2/12) showed progression; and for peripheral nodulelike enhancement, 16.7% (2/12) had not progressed and 83.3% (10/12) showed progression. The time to progression of enhancing tissue was significantly different between the group with no enhancement plus peripheral ring enhancement and the group with peripheral nodulelike enhancement (p < 0.001).

CONCLUSION

Analysis of enhancement patterns at the arterial phase of the first follow-up CT after TACE with drug-eluting beads is helpful for predicting progression of treated HCC.

Clinical utility of des-γ-carboxyprothrombin kinetics as a complement to radiologic response in patients with hepatocellular carcinoma undergoing transarterial chemoembolization

PURPOSE

Serial α-fetoprotein (AFP) measurements are useful for assessing tumor responses to numerous therapies for hepatocellular carcinoma (HCC). This study tested the predictive value of changes in des-γ-carboxy prothrombin (DCP), in parallel with AFP, as an indicator of HCC response after transarterial chemoembolization.

MATERIALS AND METHODS

The study group consisted of 327 patients with HCC initially seropositive for DCP (≥ 40 mAU/mL) and/or AFP (≥ 100 ng/mL) who underwent repeated chemoembolization as first-line therapy. Radiologic responses were measured based on modified Response Evaluation Criteria In Solid Tumors guidelines. Serologic response was defined as a decrease of at least 50% in DCP or AFP level from baseline. Radiologic-serologic correlation and disease progression and survival according to serologic responses were analyzed.

RESULTS

Before treatment, 129 patients (39%) had high DCP alone, 66 (20%) had high AFP alone, and 58 (18%) had high levels of both. Radiologic and serologic responses were achieved in 88.2% and 91.4% of patients with high DCP levels and in 89.5% and 91.1% of those with high AFP levels, respectively. Serologic response based on AFP or DCP was significantly correlated with radiologic response, and this was confirmed by landmark analysis (P < .001). DCP and AFP responders had better times to progression and overall survival than nonresponders (P < .001). Cox models revealed that both serologic responses were independent estimates of survival (hazard ratios, 0.11 for DCP and 0.14 for AFP; P < .001).

CONCLUSIONS

After transarterial chemoembolization for HCC, DCP response may be a useful surrogate endpoint of immediate and prolonged clinical outcomes, along with AFP response.

Short-term evaluation of liver tumors after transarterial chemoembolization: limitations and feasibility of contrast-enhanced ultrasonography

PURPOSE

To evaluate the limitations and the feasibility of contrast-enhanced ultrasonography (CEUS) for the assessment of tumor response shortly after transarterial chemoembolization (TACE).

MATERIALS AND METHODS

Fifty seven patients (41 patients with hepatomas, 16 patients with metastases) were studied with CEUS before, 1 day after, and 30 days after TACE. A CEUS-efficiency score (CEUS-ES) was calculated, which evaluated: (a) the completeness of visualization of the target tumor(s) (2: good, 1: adequate, 0: poor) and (b) the quality of delineation of post-TACE necroses (2: good, 1: adequate, 0: poor). A CEUS study was considered as "diagnostic," if each of the aforementioned parameters was associated with grade 1 or 2.

RESULTS

CEUS studies were "diagnostic" in 36/57 patients (63.1%). Patients with hepatomas were more likely to undergo "diagnostic" CEUS than patients with metastases (70.7% vs. 43.7%, P = 0.0728). Lesions' multiplicity, deep location, hypoenhancement on pretreatment CEUS, and diffuse growth had a statistically significant (P < 0.05) negative impact on CEUS-ES. Hyperechogenicity on pre-treatment, unenhanced US had a non-statistically significant (P = 0.176) negative impact. Differences between "diagnostic" CEUS studies and CT/MR regarding detection of residual tumor were insignificant (P = 0.8178).

CONCLUSION

The percentage of lesions which are unsuitable for post-TACE evaluation with CEUS is not negligible. For the rest, the respective role of CEUS is promising.

Quantification of tumor vascularity with contrast-enhanced ultrasound for early response of transcatheter arterial chemoembolization for hepatocellular carcinoma: a report of three cases

Many contrast-enhanced ultrasound (CE-US) studies have been conducted by qualitative analysis of blood flow, such as classification of enhancement pattern. We evaluated early response of transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) by quantitative analysis of intratumoral vascularity with CE-US in three patients. Three patients (one man, two women) with HCCs were treated in July 2009. CE-US with perfluorocarbon microbubbles (Sonazoid) and CT were performed serially before and 5 days after TACE. Post-processing enhancement intensity on US was analyzed to determine mean transit time (s), time to peak (s), enhancement peak intensity (dB), and "A" (scaling factor) by ultrasound quantification software after the data were fitted to a gamma variate curve. Mean transit time was prolonged by TACE in all three patients. Mean transit time rates on CE-US were 64.3, 33.8, and 65.6%, respectively, whereas the avascular rates on CT were 59.07, 31.71, and 62.25%, respectively. Mean transit time rates on CE-US approximated avascular rates on CT. Mean transit time rate may quantitatively indicate the early response of HCC to TACE.

Semiautomated segmentation for volumetric analysis of intratumoral ethiodol uptake and subsequent tumor necrosis after chemoembolization

OBJECTIVE

Linear measurements, such as those described by the Response Evaluation Criteria in Solid Tumors (RECIST) criteria, may be limited for assessment of response after transarterial chemoembolization (TACE). The purpose of this pilot study was to show intra- and interobserver reproducibility of volumetric measurements of Ethiodol (ethiodized oil) seen within tumor 24 hours after TACE and of necrotic and viable tumor 1 month after treatment. Volumetric measurements are compared with linear measurements and survival outcomes.

MATERIALS AND METHODS

Between 2006 and 2009, 37 consecutive TACE procedures were performed in 27 patients with hepatic malignancies. CT images obtained 24 hours and 1 month after TACE were retrospectively analyzed. Three observers measured volumes twice. Intraoperator reproducibility was determined using Wilcoxon's signed rank test to assess whether the difference in each volumetric measurement approaches zero. The intraclass correlation coefficient (ICC) and Bland-Altman plots were used to determine interoperator reproducibility. Survival data were retrospectively obtained from the electronic medical record.

RESULTS

Good intraobserver reproducibility and interobserver reproducibility (p > 0.05, ICC > 0.9, respectively) were shown for Ethiodol, whole tumor, and necrotic tumor volumes. The volume of Ethiodol correlated with subsequent necrotic tumor volume (p = 0.009), reduction in whole tumor volume (p = 0.004), and patient survival (p = 0.029). Kaplan-Meier curves suggest that Ethiodol accumulation in more than 50% of the tumor and a 10% or greater increase in the volume of necrotic tumor correlated with survival (p = 0.028 and 0.047, respectively).

CONCLUSION

Semiautomated volumetric analysis can be performed with good intra- and interobserver reproducibility. The volume of Ethiodol accumulated in the tumor after TACE correlates with subsequent necrosis. These early measurements may predict survival outcomes.

The role of perfusion CT as a follow-up modality after transcatheter arterial chemoembolization: an experimental study in a rabbit model

OBJECTIVES

To prospectively evaluate the feasibility of perfusion CT as a follow-up modality after transcatheter arterial chemoembolization (TACE) and to compare these findings with those of histopathology as the reference standard in a VX2 tumor rabbit model.

MATERIALS AND METHODS

VX2 carcinoma tumors were implanted into the liver of 20 rabbits 3 weeks prior to TACE. Perfusion CT was performed prior to TACE and 1- and 4-week after TACE. After obtaining perfusion index maps on perfusion CT, 2 radiologists measured the parametric perfusion indices of blood flow (BF), blood volume (BV), mean transit time (MTT), permeability of the capillary vessel surface (PS), and hepatic arterial fraction (HAF) of primary tumors on pre-TACE perfusion CT, chemoembolized primary tumors on 1-week perfusion CT, and recurred tumors on 4-week perfusion CT. The normal liver parenchyma indices were also recorded. In addition, the radiologists investigated the presence of a recurred tumor adjacent to the chemoembolized area on perfusion index maps of 4-week CT images. The areas of higher hepatic blood flow (HBF), hepatic blood volume (HBV), PS, and HAF, and lower MTT on 4-week perfusion CT than the normal liver parenchyma and the identical area on 1-week perfusion CT were considered as recurred tumors. Histopathology revealed the presence of a recurred tumor, and mean vessel density (MVD) was determined by immunochemical staining for CD31. CT perfusion indices were compared by use of the t test. Comparisons were made for the primary tumor versus normal liver parenchyma on pre-TACE CT, the primary tumor on pre-TACE CT versus the chemoembolized tumor on 1-week CT, the recurred tumor on 4-week CT versus the identical area on 1-week CT, and the primary tumor on pre-TACE CT versus the recurred tumor on 4-week CT. For the detection of recurred tumors, the sensitivity and specificity for 4-week perfusion CT were calculated. Correlation analysis between the recurred tumor perfusion indices and the MVD of the corresponding tumor region was performed. Among 20 rabbits, 6 were excluded from the analysis, and results were based on 14 rabbits.

RESULTS

Recurred tumors were histologically proven in 8 of 14 rabbits (57.1%). The BF, BV, PS, and HAF indices of primary tumors were significantly higher, whereas the MTT was significantly lower than that of the normal liver parenchyma on pre-TACE perfusion CT and that of chemoembolized areas on 1-week perfusion CT (P < 0.05). In addition, recurred tumors also showed significantly higher BF, BV, PS, and HAF, and lower MTT indices than the identical areas on 1-week perfusion CT (P < 0.05). The perfusion indices of recurred tumors were not significantly different from the indices of primary tumors (P > 0.05). Both sensitivity and specificity were 100% for 4-week perfusion CT. There were significant positive correlations between BF (r = 0.947), BV (r = 0.758), PS (r = 0.759), HAF (r = 0.955), and MVD in recurred tumors, and a significant inverse correlation between MTT (r = -0.782) and MVD was observed (P < 0.05).

CONCLUSIONS

We believe that perfusion CT is a feasible alternative modality for the successful early response assessment and early detection of a marginally recurred tumor after TACE. However, perfusion CT has limitations for the prediction of tumor recurrence after TACE.

Chemoembolization follow-up of hepatocellular carcinoma with MR imaging: usefulness of evaluating enhancement features on one-month posttherapy MR imaging for predicting residual disease

PURPOSE

To determine the sensitivity, specificity, and accuracy of contrast-enhanced magnetic resonance (MR) imaging performed 1 month after localized chemotherapy as a measure of tumor response, before detectable changes in size.

MATERIALS AND METHODS

This trial was approved by the authors' institutional review board and was compliant with the Health Insurance Portability and Accountability Act (HIPAA). Inclusion criteria selected patients receiving chemoembolization for hepatocellular carcinoma (HCC) with MR imaging within 2 months before treatment, in addition to MR imaging after treatment at 1 month and 6 months. Pathology was used as a surrogate for 6-month follow-up if the patient underwent interval transplantation. The final population consisted of 23 tumors (occurring within 21 patients). MR imaging studies were evaluated separately by two radiologists. Tumors were scored as showing complete loss of enhancement or as showing some residual tissue enhancement. Changes in T1 and T2 signal and perilesional enhancement were tabulated and recorded. Lesion size was also measured on all MR imaging studies by using a one-dimensional measure of the longest dimension. Increase in tumor size from 1-6 months of 20% or greater was used as confirmation of residual disease. In 5 of 23 tumors, review of pathology served as the surrogate standard. Sensitivity, specificity and accuracy were computed for each rater.

RESULTS

The sensitivity, specificity, and accuracy of 1-month follow-up MR imaging were 71.4-85.7%, 100%, and 91.3-95.7%. There was a high degree of agreement between the two readers for both the 1-month (kappa = 0.88) and 6-month (kappa = 1.0) MR imaging studies.

CONCLUSIONS

This investigation shows high accuracy for using tumor enhancement features on 1-month posttherapy MR imaging to predict residual disease after chemoembolization of HCC.

Treatment planning and volumetric response assessment for Yttrium-90 radioembolization: semiautomated determination of liver volume and volume of tumor necrosis in patients with hepatic malignancy

Purpose

The primary purpose of this study was to demonstrate intraobserver/interobserver reproducibility for novel semiautomated measurements of hepatic volume used for Yttrium-90 dose calculations as well as whole-liver and necrotic-liver (hypodense/nonenhancing) tumor volume after radioembolization. The secondary aim was to provide initial comparisons of tumor volumetric measurements with linear measurements, as defined by Response Evaluation Criteria in Solid Tumors criteria, and survival outcomes.

Methods

Between 2006 and 2009, 23 consecutive radioembolization procedures were performed for 14 cases of hepatocellular carcinoma and 9 cases of hepatic metastases. Baseline and follow-up computed tomography obtained 1 month after treatment were retrospectively analyzed. Three observers measured liver, whole-tumor, and tumor-necrosis volumes twice using semiautomated software.

Results

Good intraobserver/interobserver reproducibility was demonstrated (intraclass correlation [ICC] > 0.9) for tumor and liver volumes. Semiautomated measurements of liver volumes were statistically similar to those obtained with manual tracing (ICC = 0.868), but they required significantly less time to perform (p < 0.0001, ICC = 0.088). There was a positive association between change in linear tumor measurements and whole-tumor volume (p < 0.0001). However, linear measurements did not correlate with volume of necrosis (p > 0.05). Dose, change in tumor diameters, tumor volume, and necrotic volume did not correlate with survival (p > 0.05 in all instances). However, Kaplan–Meier curves suggest that a >10% increase in necrotic volume correlated with survival (p = 0.0472).

Conclusion

Semiautomated volumetric analysis of liver, whole-tumor, and tumor-necrosis volume can be performed with good intraobserver/interobserver reproducibility. In this small retrospective study, measurements of tumor necrosis were suggested to correlate with survival.

Hepatocellular carcinoma: CT for tumor response after transarterial chemoembolization in patients exceeding Milan criteria--selection parameter for liver transplantation

PURPOSE

To retrospectively evaluate the clinical outcome of patients with hepatocellular carcinoma (HCC) who exceeded the Milan criteria, who underwent transarterial chemoembolization (TACE) before orthotopic liver transplantation (OLT), to determine the value of computed tomography (CT)-based tumor response to TACE as a preoperative selection criterion for OLT.

MATERIALS AND METHODS

The study included 33 patients with HCC who exceeded the Milan criteria and underwent OLT after TACE. Informed written consent was obtained before TACE and OLT. Institutional review board approval was not required. Tumor response to TACE was evaluated at 1 month with CT according to amended Response Evaluation Criteria in Solid Tumours (RECIST) guidelines. In the explanted liver, degree of tumor necrosis (> or = 90%, 50%-89%, or < 50%), residual tumor stage and grade, and presence of microvascular invasion were assessed. Follow-up after OLT ranged from 1 to 143 months.

RESULTS

After TACE, CT showed complete tumor response (CR) in 18 (55%) patients. On the explanted liver, tumor necrosis was rated 90% or greater in 20 (61%) patients, with a good correlation with CT. Microvascular invasion was observed in nine (27%) of 33 patients; none of them were reported to have a CR at CT. The 5-year cumulative survival rate after OLT was 72.5%; it was significantly (P = .003) higher in patients with a CR (94.4%) compared with patients with a partial response (PR) (45.4%) and stable disease (50%). The 5-year cumulative recurrence-free rate after OLT was 74.4%; it was not affected by the tumor nodule size and number, whereas it was significantly (P = .008) higher in patients with a CR (94.4%) compared with patients with a PR (46.7%) and stable disease (50%).

CONCLUSION

In patients with HCC who exceeded the Milan criteria, a CR after TACE, on the basis of amended RECIST guidelines, is associated with excellent posttransplantation outcomes. Therefore, 1-month response to TACE assessed at CT may represent a valid selection criterion for OLT.

Radiologic-pathologic correlation of hepatocellular carcinoma treated with chemoembolization

To correlate posttreatment radiologic and pathologic findings in patients who underwent transarterial chemoembolization before transplantation or resection. Thirty-five patients with postchemoembolization follow-up imaging underwent liver transplantation/resection. Pre- and posttreatment contrast-enhanced magnetic resonance imaging were used to evaluate radiologic findings. Imaging characteristics using World Health Organization (WHO) and European Association for the Study of the Liver (EASL) criteria after treatment were evaluated. Treated lesions were examined by pathology (gold standard) for the assessment of necrosis. Radiologic findings on magnetic resonance imaging were correlated to pathologic findings to assess the predictability by imaging of actual necrosis. Kappa (κ) statistics were used to determine intermethod agreement between WHO and EASL criteria. Fourteen (40%) of 35 lesions had biopsy-proven hepatocellular carcinoma. Thirteen (37%) of 35 target lesions showed complete pathologic necrosis. Complete pathologic necrosis was seen in 35% of lesions with pretreatment size <3 cm. Complete pathologic necrosis was seen in 1 (100%) of 1, 6 (67%) of 9, 6 (33%) of 18, and 0 (0%) of 7 of the lesions that exhibited complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD) by WHO criteria, respectively. Complete pathologic necrosis was seen in 9 (82%) of 11, 4 (36%) of 11, 0 (0%) of 8, and 0 (0%) of 5 of the lesions that showed CR, PR, SD, or PD by EASL criteria, respectively. EASL CR and WHO response were shown to have ≥85% specificity for predicting complete pathologic necrosis. The κ coefficient for agreement between WHO and EASL was 0.29. EASL and WHO criteria had minimal intermethod agreement. EASL CR and WHO response were able to predict pathologic necrosis.

Visualization and segmentation of liver tumors using dynamic contrast MRI

Hepatocellular carcinoma (liver tumor) is one of the most common malignancies causing an estimated one million deaths annually, and the fastest growing form of cancer in the United States. Dynamic Contrast Enhanced MRI (DCE-MRI) is a useful way to characterize tumor response to contrast agent uptake, but the method still lacks maturity in terms of quantifying tumor burden and viability. We propose a semi-supervised technique for visualizing and measuring liver tumor burden and viability from DCE-MRI examinations. In order to solve the challenging segmentation problem, we exploit prior information about the spatio-temporal characteristics of DCE-MRI data, and perform k-means clustering in a hybrid intensity-spatial feature space.