Evaluation of HCC response to locoregional therapy: Validation of MRI-based response criteria versus explant pathology

Neoadjuvant therapies in resectable hepatocellular carcinoma: Exploring strategies to improve prognosis

Hepatocellular carcinoma (HCC), a challenging malignancy, often necessitates surgical intervention, notably liver resection. However, the high recurrence rate, reaching 70% within 5 years post-resection, significantly impacts patient outcomes. Neoadjuvant therapies aim to preoperatively address this challenge, reducing lesion size, improving surgical resection rates, deactivating potential micro-metastases, and ultimately lowering postoperative recurrence rates. This review concentrates on advances in research on and clinical use of neoadjuvant therapies for HCC, with particular attention to the use of immune checkpoint inhibitors (ICIs) targeting programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4). Ongoing clinical studies exploring immunotherapy combined with a tyrosine kinase inhibitor (TKI), interventional therapy, radiotherapy, and other modalities offer promising insights into overcoming resistance to monotherapies. In summary, neoadjuvant therapies hold significant promise in terms of improving the prognosis for patients with HCC and enhancing long-term survival, particularly through innovative combination strategies.

Early post-treatment MRI predicts long-term hepatocellular carcinoma response to radiation segmentectomy

OBJECTIVES

Radiation segmentectomy using yttrium-90 plays an emerging role in the management of early-stage HCC. However, the value of early post-treatment MRI for response assessment is uncertain. We assessed the value of response criteria obtained early after radiation segmentectomy in predicting long-term response in patients with HCC.

MATERIALS AND METHODS

Patients with HCC who underwent contrast-enhanced MRI before, early, and 12 months after radiation segmentectomy were included in this retrospective single-center study. Three independent radiologists reviewed images at baseline and 1st follow-up after radiation segmentectomy and assessed lesion-based response according to mRECIST, LI-RADS treatment response algorithm (TRA), and image subtraction. The endpoint was response at 12 months based on consensus readout of two separate radiologists. Diagnostic accuracy for predicting complete response (CR) at 12 months based on the 1st post-treatment MRI was calculated.

RESULTS

Eighty patients (M/F 60/20, mean age 67.7 years) with 80 HCCs were assessed (median size baseline, 1.8 cm [IQR, 1.4-2.9 cm]). At 12 months, 74 patients were classified as CR (92.5%), 5 as partial response (6.3%), and 1 as progressive disease (1.2%). Diagnostic accuracy for predicting CR was fair to good for all readers with excellent positive predictive value (PPV): mRECIST (range between 3 readers, accuracy: 0.763-0.825, PPV: 0.966-1), LI-RADS TRA (accuracy: 0.700-0.825, PPV: 0.983-1), and subtraction (accuracy: 0.775-0.825, PPV: 0.967-1), with no difference in accuracy between criteria (p range 0.053 to > 0.9).

CONCLUSION

mRECIST, LI-RADS TRA, and subtraction obtained on early post-treatment MRI show similar performance for predicting long-term response in patients with HCC treated with radiation segmentectomy.

CLINICAL RELEVANCE STATEMENT

Response assessment extracted from early post-treatment MRI after radiation segmentectomy predicts complete response in patients with HCC with high PPV (≥ 0.96).

KEY POINTS

• Early post-treatment response assessment on MRI predicts response in patients with HCC treated with radiation segmentectomy with fair to good accuracy and excellent positive predictive value. • There was no difference in diagnostic accuracy between mRECIST, LI-RADS, and subtraction for predicting HCC response to radiation segmentectomy.

Longitudinal assessment of hepatocellular carcinoma response to stereotactic body radiation using gadoxetate-enhanced MRI: A case series

PURPOSE

To describe the longitudinal response in patients with hepatocellular carcinoma (HCC) treated with stereotactic body radiation therapy (SBRT) and who underwent liver transplant (LT) using gadoxetate-enhanced MRI.

METHODS

Five men (median age 61y, range 57-64y) with 6 HCCs treated with SBRT (median dose 50 Gy) who subsequently underwent LT were included in this retrospective study. Patients underwent gadoxetate-enhanced MRI before and after SBRT over a period of 3-18 months. Response was assessed using RECIST1.1, mRECIST, LI-RADS and image subtraction, by 2 observers in consensus. Percentage of pathologic tumor necrosis was evaluated.

RESULTS

LT was performed 278 days (IQR, 148-418d) after completion of SBRT and 48d after the last MRI. Histopathology demonstrated tumor necrosis of 48 ± 42% (range, 10-100%). Mean tumor size at baseline and last post-treatment MRIs pre-LT were 2.6 ± 0.8 cm and 2.4 ± 0.9 cm. Enhancing tumor component size at baseline MRI and last post-treatment MRI pre-LT were 1.6 ± 0.8 cm and 0.9 ± 1.0 cm. Responses assessed at the last LRI pre-LT were: partial response (PR, n = 3), stable disease (SD, n = 3) using RECIST1.1; complete response (CR, n = 2), partial response (PR, n = 2), stable disease (SD, n = 2) using mRECIST; and LR-TR viable (n = 4), LR-TR non-viable (n = 2) using LI-RADS. At the last MRI pre-LT, per-lesion features of arterial phase hyperenhancement (APHE, 4/6), portal venous washout (3/6) and capsule (3/6) were observed. 5/6 lesions displayed a hypointense perilesional halo on hepatobiliary phase with a mean delay of 3.1 months post-SBRT.

CONCLUSIONS

This case-series showed decreased size, persistent APHE, and incomplete pathologic necrosis in most HCCs treated with SBRT undergoing transplant.

Semiautomated segmentation of hepatocellular carcinoma tumors with MRI using convolutional neural networks

OBJECTIVE

To assess the performance of convolutional neural networks (CNNs) for semiautomated segmentation of hepatocellular carcinoma (HCC) tumors on MRI.

METHODS

This retrospective single-center study included 292 patients (237 M/55F, mean age 61 years) with pathologically confirmed HCC between 08/2015 and 06/2019 and who underwent MRI before surgery. The dataset was randomly divided into training (n = 195), validation (n = 66), and test sets (n = 31). Volumes of interest (VOIs) were manually placed on index lesions by 3 independent radiologists on different sequences (T2-weighted imaging [WI], T1WI pre-and post-contrast on arterial [AP], portal venous [PVP], delayed [DP, 3 min post-contrast] and hepatobiliary phases [HBP, when using gadoxetate], and diffusion-weighted imaging [DWI]). Manual segmentation was used as ground truth to train and validate a CNN-based pipeline. For semiautomated segmentation of tumors, we selected a random pixel inside the VOI, and the CNN provided two outputs: single slice and volumetric outputs. Segmentation performance and inter-observer agreement were analyzed using the 3D Dice similarity coefficient (DSC).

RESULTS

A total of 261 HCCs were segmented on the training/validation sets, and 31 on the test set. The median lesion size was 3.0 cm (IQR 2.0-5.2 cm). Mean DSC (test set) varied depending on the MRI sequence with a range between 0.442 (ADC) and 0.778 (high b-value DWI) for single-slice segmentation; and between 0.305 (ADC) and 0.667 (T1WI pre) for volumetric-segmentation. Comparison between the two models showed better performance in single-slice segmentation, with statistical significance on T2WI, T1WI-PVP, DWI, and ADC. Inter-observer reproducibility of segmentation analysis showed a mean DSC of 0.71 in lesions between 1 and 2 cm, 0.85 in lesions between 2 and 5 cm, and 0.82 in lesions > 5 cm.

CONCLUSION

CNN models have fair to good performance for semiautomated HCC segmentation, depending on the sequence and tumor size, with better performance for the single-slice approach. Refinement of volumetric approaches is needed in future studies.

KEY POINTS

• Semiautomated single-slice and volumetric segmentation using convolutional neural networks (CNNs) models provided fair to good performance for hepatocellular carcinoma segmentation on MRI. • CNN models' performance for HCC segmentation accuracy depends on the MRI sequence and tumor size, with the best results on diffusion-weighted imaging and T1-weighted imaging pre-contrast, and for larger lesions.

Intratumoral Immunotherapy: Is It Ready for Prime Time?

PURPOSE OF REVIEW

This review presents the rationale for intratumoral immunotherapy, technical considerations and safety. Clinical results from the latest trials are provided and discussed.

RECENT FINDINGS

Intratumoral immunotherapy is feasible and safe in a wide range of cancer histologies and locations, including lung and liver. Studies mainly focused on multi-metastatic patients, with some positive trials such as T-VEC in melanoma, but evidence of clinical benefit is still lacking. Recent results showed improved outcomes in patients with a low tumor burden. Intratumoral immunotherapy can lower systemic toxicities and boost local and systemic immune responses. Several studies have proven the feasibility, repeatability, and safety of this approach, with some promising results in clinical trials. The clinical benefit might be improved in patients with a low tumor burden. Future clinical trials should focus on adequate timing of treatment delivery during the course of the disease, particularly in the neoadjuvant setting.

The prognostic role of early tumor shrinkage in patients with hepatocellular carcinoma undergoing immunotherapy

Background

Early tumor shrinkage (ETS) has been identified as a promising imaging biomarker for patients undergoing immunotherapy for several cancer entities. This study aimed to validate the potential of ETS as an imaging biomarker for patients undergoing immunotherapy for hepatocellular carcinoma (HCC).

Methods

We screened all patients with HCC that received immunotherapy as the first or subsequent line of treatment at our tertiary care center between 2016 and 2021. ETS was defined as the reduction in the sum of the sizes of target lesions, between the initial imaging and the first follow-up. The ETS was compared to the radiologic response, according to the modified response evaluation criteria in solid tumors (mRECIST). Furthermore, we evaluated the influence of ETS on overall survival (OS), progression-free survival (PFS), and the alpha-fetoprotein (AFP) response.

Results

The final analysis included 39 patients with available cross-sectional imaging acquired at the initiation of immunotherapy (baseline) and after 8–14 weeks. The median ETS was 5.4%. ETS was significantly correlated with the response according to mRECIST and with the AFP response. Patients with an ETS ≥10% had significantly longer survival times after the first follow-up, compared to patients with < 10% ETS (15.1 months vs. 4.0 months, p = 0.008). Additionally, patients with both an ETS ≥10% and disease control, according to mRECIST, also had significantly prolonged PFS times after the initial follow-up (23.6 months vs. 2.4 months, p < 0.001).

Conclusion

ETS was strongly associated with survival outcomes in patients with HCC undergoing immunotherapy. Thus, ETS is a readily assessable imaging biomarker that showed potential for facilitating a timely identification of patients with HCC that might benefit from immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-022-00487-x.

Role of 18F-FDG PET/CT in assessment of HCC patients after therapeutic interventions compared to DW MRI

Background

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related deaths worldwide in both men and women. Early-stage HCCs are treated either by curative surgical resection and/or by locoregional interventions, such as radiofrequency ablation or trans-arterial chemoembolization. Functional imaging as diffusion-weighted magnetic resonance imaging (DW MRI) and metabolic imaging with 18F-positron emission tomography/computed tomography (18F-FDG PET/CT) has been used for assessment of treatment response. This retrospective study was conducted on 29 patients known to have HCC with locoregional therapeutic interventions and referred for radiological follow-up searching for residual/recurrence neoplasia or metastatic deposits. The study aimed to assess the benefits of using the metabolic parameters of 18F-FDG PET/CT in the follow-up of HCC patients after therapeutic interventions in comparison with DW MRI.

Results

Regarding qualitative assessment of residual active viable HCC by PET/CT and DW MRI, the sensitivity, specificity, PPV, NPP and accuracy were 77.3%, 91.7%, 94.4%, 68.8%, 82.4% and 95.5%, 75%, 87.5%, 90%, 88.2%, respectively. The optimal cutoff point of the SUVmax to differentiate viable from non-viable HCC was 3.4 (AUC = 0.898), with sensitivity, specificity, PPV and NPV of 77.27%, 100.0%, 100.0% and 66.7%, respectively. The optimal ADC cutoff value for discrimination between viable and non-viable HCC was 1247 mm2/s (AUC = 0.976) with sensitivity, specificity, PPV and NPV of 90.48%, 100.0%, 100.0% and 83.3%, respectively. New hepatic lesions were found in 38.2% of patients by DW MRI, while detected only in 26.5% of patients by PET/CT. The PET/CT revealed extrahepatic metastasis in 44.1% of patients, while detected only in 8.8% of patients by DW MRI.

Conclusions

DWI was more sensitive than PET/CT for detecting tumor residual and hepatic recurrence compared to PET/CT which was much better in detecting distant metastases.

Optimal imaging criteria and modality to determine Milan criteria for the prediction of post-transplant HCC recurrence after locoregional treatment

OBJECTIVES

We aimed to investigate the optimal radiologic method to determine Milan criteria (MC) for the prediction of recurrence in patients who underwent locoregional treatment (LRT) for hepatocellular carcinoma (HCC) and subsequent liver transplantation (LT).

METHODS

This retrospective study included 121 HCC patients who underwent LRT and had both liver dynamic CT and MRI. They were classified with MC using four cross combinations of two imaging modalities (CT and MRI) and two diagnostic criteria (modified Response Evaluation Criteria in Solid Tumors [mRECIST] and Liver Imaging Reporting and Data System treatment response algorithm [LI-RADS TRA]). Competing risk regression was performed to analyze the time to recurrence after LT. The predictive abilities of the four methods for recurrence were evaluated using the time-dependent area under the curve (AUC).

RESULTS

Competing risk regression analyses found that beyond MC determined by MRI with mRECIST was independently associated with recurrence (hazard ratio, 6.926; p = 0.001). With mRECIST, MRI showed significantly higher AUCs than CT at 3 years and 5 years after LT (0.597 vs. 0.756, p = 0.012 at 3 years; and 0.588 vs. 0.733, p = 0.024 at 5 years). Using the pathologic reference standard, MRI with LI-RADS TRA showed higher sensitivity (61.5%) than CT with LI-RADS TRA (30.8%, p < 0.001) or MRI with mRECIST (38.5%, p < 0.001).

CONCLUSIONS

MRI with mRECIST was the optimal radiologic method to determine MC for the prediction of post-LT recurrence in HCC patients with prior LRT.

KEY POINTS

• MRI with modified RECIST (mRECIST) is the optimal preoperative method to determine Milan criteria for the prediction of post-transplant HCC recurrence in patients with prior locoregional treatment. • With mRECIST, MRI was better than CT for the prediction of post-transplant recurrence.

Patient Selection for Downstaging of Hepatocellular Carcinoma Prior to Liver Transplantation—Adjusting the Odds?

Background and Aims: Morphometric features such as the Milan criteria serve as standard criteria for liver transplantation (LT) in patients with hepatocellular carcinoma (HCC). Since it has been recognized that these criteria are too restrictive and do not adequately display the tumor biology, additional selection parameters are emerging.

Methods: Concise review of the current literature on patient selection for downstaging and LT for HCC outside the Milan criteria.

Results: The major task in patients outside the Milan criteria is the need for higher granularity with patient selection, since the benefit through LT is not uniform. The recent literature clearly shows that beneath tumor size and number, additional selection parameters are useful in the process of patient selection for and during downstaging. For initial patient selection, the alpha fetoprotein (AFP) level adds additional information to the size and number of HCC nodules concerning the chance of successful downstaging and LT. This effect is quantifiable using newer selection tools like the WE (West-Eastern) downstaging criteria or the Metroticket 2.0 criteria. Also an initial PET-scan and/or tumor biopsy can be helpful, especially in the high risk group of patients outside the University of California San Francisco (UCSF) criteria. After this entry selection, the clinical course during downstaging procedures concerning the tumor and the AFP response is of paramount importance and serves as an additional final selection tool.

Conclusion: Selection criteria for liver transplantation in HCC patients are becoming more and more sophisticated, but are still imperfect. The implementation of molecular knowledge will hopefully support a more specific risk prediction for HCC patients in the future, but do not provide a profound basis for clinical decision-making at present.

Assessment of HCC response to Yttrium-90 radioembolization with gadoxetate disodium MRI: correlation with histopathology

BACKGROUND AND AIMS

Transarterial ⁹⁰Y radioembolization (TARE) is increasingly being used for hepatocellular carcinoma (HCC) treatment. However, tumor response assessment after TARE may be challenging. We aimed to assess the diagnostic performance of gadoxetate disodium MRI for predicting complete pathologic necrosis (CPN) of HCC treated with TARE, using histopathology as the reference standard.

METHODS

This retrospective study included 48 patients (M/F: 36/12, mean age: 62 years) with HCC treated by TARE followed by surgery with gadoxetate disodium MRI within 90 days of surgery. Two radiologists evaluated tumor response using RECIST1.1, mRECIST, EASL, and LI-RADS-TR criteria and evaluated the percentage of necrosis on subtraction during late arterial, portal venous, and hepatobiliary phases (AP/PVP/HBP). Statistical analysis included inter-reader agreement, correlation between radiologic and pathologic percentage of necrosis, and prediction of CPN using logistic regression and ROC analyses.

RESULTS

Histopathology demonstrated 71 HCCs (2.8 ± 1.7 cm, range: 0.5-7.5 cm) including 42 with CPN, 22 with partial necrosis, and 7 without necrosis. EASL and percentage of tumor necrosis on subtraction at the AP/PVP were independent predictors of CPN (p = 0.02-0.03). Percentage of necrosis, mRECIST, EASL, and LI-RADS-TR had fair to good performance for diagnosing CPN (AUCs: 0.78 - 0.83), with a significant difference between subtraction and LI-RADS-TR for reader 2, and in specificity between subtraction and other criteria for both readers (p-range: 0.01-0.04). Radiologic percentage of necrosis was significantly correlated to histopathologic degree of tumor necrosis (r = 0.66 - 0.8, p < 0.001).

CONCLUSIONS

Percentage of tumor necrosis on subtraction and EASL criteria were significant independent predictors of CPN in HCC treated with TARE. Image subtraction should be considered for assessing HCC response to TARE when using MRI.

KEY POINTS

• Percentage of tumor necrosis on image subtraction and EASL criteria are significant independent predictors of complete pathologic necrosis in hepatocellular carcinoma treated with⁹⁰Y radioembolization. • Subtraction, mRECIST, EASL, and LI-RADS-TR have fair to good performance for diagnosing complete pathologic necrosis in hepatocellular carcinoma treated with⁹⁰Y radioembolization.

Neoadjuvant cemiplimab for resectable hepatocellular carcinoma: a single-arm, open-label, phase 2 trial

BACKGROUND

Surgical resection of early stage hepatocellular carcinoma is standard clinical practice; however, most tumours recur despite surgery, and no perioperative intervention has shown a survival benefit. Neoadjuvant immunotherapy has induced pathological responses in multiple tumour types and might decrease the risk of postoperative recurrence in hepatocellular carcinoma. We aimed to evaluate the clinical activity of neoadjuvant cemiplimab (an anti-PD-1) in patients with resectable hepatocellular carcinoma.

METHODS

For this single-arm, open-label, phase 2 trial, patients with resectable hepatocellular carcinoma (stage Ib, II, and IIIb) were enrolled and received two cycles of neoadjuvant cemiplimab 350 mg intravenously every 3 weeks followed by surgical resection. Eligible patients were aged 18 years or older, had confirmed resectable hepatocellular carcinoma, an Eastern Cooperative Oncology Group performance status of 0 or 1, and adequate liver function. Patients were excluded if they had metastatic disease, if the surgery was not expected to be curative, if they had a known additional malignancy requiring active treatment, or if they required systemic steroid treatment or any other immunosuppressive therapy. After resection, patients received an additional eight cycles of cemiplimab 350 mg intravenously every 3 weeks in the adjuvant setting. The primary endpoint was significant tumour necrosis on pathological examination (defined as >70% necrosis of the resected tumour). Secondary endpoints included delay of surgery, the proportion of patients with an overall response, change in CD8+ T-cell density, and adverse events. Tumour necrosis and response were analysed in all patients who received at least one dose of cemiplimab and completed surgical resection; safety and other endpoints were analysed in the intention-to-treat population. Patients underwent pre-treatment biopsies and blood collection throughout treatment. This trial is registered with ClinicalTrials.gov (NCT03916627, Cohort B) and is ongoing.

FINDINGS

Between Aug 5, 2019, and Nov 25, 2020, 21 patients were enrolled. All patients received neoadjuvant cemiplimab, and 20 patients underwent successful resection. Of the 20 patients with resected tumours, four (20%) had significant tumour necrosis. Three (15%) of 20 patients had a partial response, and all other patients maintained stable disease. 20 (95%) patients had a treatment-emergent adverse event of any grade during the neoadjuvant treatment period. The most common adverse events of any grade were increased aspartate aminotransferase (in four patients), increased blood creatine phosphokinase (in three), constipation (in three), and fatigue (in three). Seven patients had grade 3 adverse events, including increased blood creatine phosphokinase (in two patients) and hypoalbuminaemia (in one). No grade 4 or 5 events were observed. One patient developed pneumonitis, which led to a delay in surgery by 2 weeks.

INTERPRETATION

This report is, to our knowledge, the largest clinical trial of a neoadjuvant anti-PD-1 monotherapy reported to date in hepatocellular carcinoma. The observed pathological responses to cemiplimab in this cohort support the design of larger trials to identify the optimal treatment duration and definitively establish the clinical benefit of preoperative PD-1 blockade in patients with hepatocellular carcinoma.

FUNDING

Regeneron Pharmaceuticals.

Outcomes of patients presenting with elevated tumor marker levels but negative gadoxetic acid-enhanced liver MRI after a complete response to hepatocellular carcinoma treatment

Purpose

Hepatocellular carcinoma (HCC) patients usually achieve a complete response after treatment. This study was aimed to assess the clinical outcome of HCC patients who had achieved a complete response but later presented with elevated tumor marker levels without an identifiable recurrent tumor on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

Methods

We retrospectively reviewed the clinical outcome of 58 HCC treated patients who had achieved a complete response but later was referred to our institution’s multidisciplinary tumor board for a clinically suspected hidden HCC recurrence based on elevated tumor marker levels but negative gadoxetic acid-enhanced MRI. The imaging studies, tumor markers, and clinical information were reviewed. The total follow-up period was at least 15 months after the initial negative gadoxetic acid-enhanced MRI.

Results

Follow-up imaging studies detected an HCC lesion in 89.7% (n = 52/58) of the patients within the study period, and approximately half of the tumors (46.2%, n = 24/52) developed within 3 months. The most frequent site of recurrence was the liver (86.5%; n = 45/52), but extra-hepatic metastasis was also common (19.2%; n = 10/52). In 5.8% (n = 3/52), HCC reoccurred in the combined form of intra-hepatic and extra-hepatic recurrence. Extra-hepatic metastasis alone occurred in 13.5% (n = 7/52) of patients.

Conclusions

HCC frequently recurred within a short interval in patients who achieved a complete response to treatment in the presence of increased tumor marker levels, even if gadoxetic acid-enhanced MRI was negative. Under such circumstances, we suggest a short-term follow-up including, but not limited to, gadoxetic acid-enhanced MRI along with systemic evaluation.

Incorporation of Ancillary MRI Features into the LI-RADS Treatment Response Algorithm: Impact on Diagnostic Performance After Locoregional Treatment for Hepatocellular Carcinoma

Background: The LI-RADS treatment response algorithm may lack sufficient sensitivity for viable tumor after locoregional treatment (LRT) for hepatocellular carcinoma (HCC). Objective: To evaluate the impact of incorporation of ancillary MRI features on the diagnostic performance of the LI-RADS treatment response algorithm after LRT for HCC. Methods: This retrospective study included 141 patients (114 men, 27 women; median age, 56 years) who underwent gadoxetic acid-enhanced MRI following LRT for HCC between October 2005 and January 2020 and subsequent liver surgery. Two readers assessed lesions for LI-RADS features of viability and for ancillary features [transitional phase (TP) hypointensity, hepatobiliary phase (HBP) hypointensity, DWI hyperintensity or low ADC, mild-to-moderate T2 hyperintensity]. Interobserver agreement was assessed before reaching consensus. Significant ancillary features were identified using random forest analysis. Impact of incorporation of significant ancillary features on diagnostic performance for incomplete pathologic necrosis (IPN, pathologically viable tumor >0 mm) was assessed using McNemar tests. Results: Complete pathologic necrosis (CPN) was observed in 88/181 (48.6%) lesions. Inter-reader agreement was almost perfect (κ=0.92-0.97) for LI-RADS features of viability and substantial to almost perfect (κ=0.73-0.94) for ancillary features. Random forest analysis identified TP hypointensity (present in 8.0%, 25.0%, and 75.3% of lesions with CPN, viable tumor <10 mm, and viable tumor ≥10 mm, respectively) and HBP hypointensity (9.2%, 25.0%, and 74.0%, respectively) as significant ancillary features. For detecting IPN, LR-TR Viable OR LR-TR Equivocal had higher sensitivity (71.0% vs 57.0%, P = .001), but lower specificity (86.4% vs 94.3%, P = .02) than LR-TR Viable. However, LR-TR Viable OR LR-TR Equivocal and TP hypointensity showed higher sensitivity (64.5% vs 57.0%, P = .02) than LR-TR Viable, without significantly different specificity (90.9% vs 94.3%, P = .25). LR-TR Viable OR LR-TR Equivocal and HBP hypointensity also showed higher sensitivity (65.6% vs 57.0%, P = .01) than LR-TR Viable, without significantly different specificity (90.8% vs. 94.3%, P = .25). Conclusion: TP hypointensity and HBP hypointensity increase sensitivity of LI-RADS treatment response algorithm for viable tumor without lowering specificity. Clinical Impact: The two identified ancillary features may improve tumor viability assessment and planning of additional therapies after LRT for HCC.

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.

Inter-center agreement of mRECIST in transplanted patients for hepatocellular carcinoma

OBJECTIVES

To evaluate the inter-observer reliability of modified Response Evaluation Criteria In Solid Tumours (mRECIST) of patients with hepatocellular carcinoma (HCC) undergoing neo-adjuvant treatments before liver transplant (LT). The agreement of tumor number, size, transplant criteria, and the radiological-pathological concordance were also assessed.

METHODS

A total of 180 radiological studies before/after neo-adjuvant therapies performed on 90 patients prior to LT were reviewed from three expert centers. Kappa-statistic and intraclass correlation (ICC) were evaluated on mRECIST and on tumoral features. Complete radiological response (CR) was compared with complete pathological response (CPR).

RESULTS

Before neo-adjuvant therapies, the agreement on tumor number, size, and transplant criteria ranged from moderate (defined as ICC of 0.41-0.60) to almost perfect (ICC of 0.81-0.99), being higher with magnetic resonance imaging (MRI) than CT (0.657-0.899 and 0.422-0.776, respectively). After neo-adjuvant therapies, the agreement decreased, as ICCs ranged between 0.518 and 0.663 with MRI and between 0.508 and 0.677 with CT. Concordant mRECIST pairs were 201 of 270 reviews (76.3%) with a kappa of 0.648 indicating substantial agreement. When the three observers completely agreed on CR, the positive predictive value for CPR was 51.6%. The negative predictive value was 94.2% with a kappa of 0.512 indicating fair agreement between radiology and pathology.

CONCLUSIONS

mRECIST agreement was substantial among the three observers involved. The agreement on tumor number, size, and transplant criteria ranged from moderate to almost perfect, with the highest ICCs obtained with MRI before neo-adjuvant therapies. Finally, the predictive value of mRECIST in the diagnosis of CPR was only fair.

KEY POINTS

• The review of 180 radiological exams of patients with hepatocellular carcinoma before and after neo-adjuvant therapies showed that the concordance among three different raters on mRECIST diagnosis was substantial. • The inter-observer reliability on fulfilment of transplant criteria slightly decreased when evaluated through CT and after loco-regional therapies. • The radiological diagnosis of complete response after neo-adjuvant therapies was predictive of complete pathological response in only 51.6% of cases.

18F-choline PET-computed tomography for the prediction of early treatment responses to transarterial radioembolization in patients with hepatocellular carcinoma

BACKGROUND

Transarterial radioembolization (TARE) is widely used for the treatment of hepatocellular carcinoma (HCC), but early treatment response can be very difficult to assess. The aim was to evaluate 18F-fluorocholine PET/computed tomography (CT) to assess the treatment response in patients with intermediate or locally advanced HCC.

METHODS

Between March 2019 and July 2020, nine HCC patients treated with TARE, who underwent PET/CT at baseline and 1 month after treatment, were enrolled. The maximum, mean (SUVmean), and peak (SUVpeak) standardized uptake value (SUV), SUV normalized by lean body mass (SUL), and total lesion glycolysis (TLG) were measured. Statistical analysis used the Mann-Whitney test to evaluate the differences in parameters between responders (partial and complete response) and nonresponders (stable or progressive disease) at the 6-month follow-up, according to the modified Response Evaluation Criteria in Solid Tumors.

RESULTS

Three patients were nonresponders (progressive disease and stable disease) and six were responders. Delta SUVmean, delta SUL, and delta TLG could predict an early response (P = 0.02, P = 0.04, and P = 0.02, respectively). None of the pre-therapeutic parameters were correlated with the response. Post-therapeutic SUL, SUVmean, TLG, and SUVpeak were also predictive of the response.

CONCLUSIONS

Our preliminary results showed that changes in certain metabolic parameters (from baseline PET to 1-month PET) are predictive of the response to TARE in HCC (Delta SUVmean, delta TLG, and delta SUL). The absence of post-treatment inflammation could lead to a better prediction than MRI evaluation. This study suggests that 1-month 18F-choline PET/CT could modify the clinical management predicting responders.Video Abstract: http://links.lww.com/NMC/A193.

Usefulness of Arterial Subtraction in Applying Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Algorithm to Gadoxetic Acid-Enhanced MRI

Objective

We aimed to evaluate the usefulness of arterial subtraction images for predicting the viability of hepatocellular carcinoma (HCC) after locoregional therapy (LRT) using gadoxetic acid-enhanced MRI and the Liver Imaging Reporting and Data System treatment response (LR-TR) algorithm.

Materials and Methods

This study included 90 patients (mean age ± standard deviation, 57 ± 9 years) who underwent liver transplantation or resection after LRT and had 73 viable and 32 nonviable HCCs. All patients underwent gadoxetic acid-enhanced MRI before surgery. Two radiologists assessed the presence of LR-TR features, including arterial phase hyperenhancement (APHE) and LR-TR categories (viable, nonviable, or equivocal), using ordinary arterial-phase and arterial subtraction images. The reference standard for tumor viability was surgical pathology. The sensitivity of APHE for diagnosing viable HCC was compared between ordinary arterial-phase and arterial subtraction images. The sensitivity and specificity of the LR-TR algorithm for diagnosing viable HCC was compared between the use of ordinary arterial-phase and the use of arterial subtraction images. Subgroup analysis was performed on lesions treated with transarterial chemoembolization (TACE) only.

Results

The sensitivity of APHE for viable HCCs was higher for arterial subtraction images than ordinary arterial-phase images (71.2% vs. 47.9%; p < 0.001). LR-TR viable category with the use of arterial subtraction images compared with ordinary arterial-phase images showed a significant increase in sensitivity (76.7% [56/73] vs. 63.0% [46/73]; p = 0.002) without significant decrease in specificity (90.6% [29/32] vs. 93.8% [30/32]; p > 0.999). In a subgroup of 63 lesions treated with TACE only, the use of arterial subtraction images showed a significant increase in sensitivity (81.4% [35/43] vs. 67.4% [29/43]; p = 0.031) without significant decrease in specificity (85.0% [17/20] vs. 90.0% [18/20]; p > 0.999).

Conclusion

Use of arterial subtraction images compared with ordinary arterial-phase images improved the sensitivity while maintaining specificity for diagnosing viable HCC after LRT using gadoxetic acid-enhanced MRI and the LR-TR algorithm.

The Key Role of Staging Definitions for Assessment of Downstaging for Hepatocellular Carcinoma

The success of liver transplant (LT) for hepatocellular carcinoma (HCC) is dependent on accurate tumor staging using validated imaging criteria, and adherence to acceptable criteria based on tumor size and number. Other factors including α-fetoprotein (AFP) and response to local regional therapy (LRT) have now played a larger role in candidate selection. Tumor downstaging is defined as reduction in the size of viable tumors using LRT to meet acceptable criteria for LT, and serves as a selection tool for a subgroup of HCC with more favorable biology. The application of tumor downstaging requires a structured approach involving three key components in tumor staging-initial tumor stage and eligibility criteria, tumor viability assessment following LRT, and target tumor stage prior to LT-and incorporation of AFP into staging and treatment response assessments. In this review, we provide in-depth discussions of the key role of these staging definitions in ensuring successful outcome.

Microwave Ablation of Small Hepatic Metastases Using MR Guidance and Monitoring: Clinical Safety and Efficacy

Background

To evaluate the technical success and clinical safety of magnetic resonance (MR)-guided microwave ablation (MWA) of small hepatic metastases.

Materials and Methods

Institutional review board approval and informed patient consent were obtained. A retrospective analysis of the patient data revealed 50 patients with small hepatic metastases (34 men, 16 women) who underwent MWA under MR guidance and monitoring. After the procedure, the intervention-related complications were classified according to the Common Terminology Criteria for Adverse Events (CTCAE) and Society of Interventional Radiology (SIR) classification system. Furthermore, the overall survival (OS) and local tumor-free survival (LTP) of the patients were analyzed.

Results

The patients who underwent MR-guided MWA achieved technical success. The mean energy, ablation duration per tumor, and procedure duration were 55.3 ± 9.4 kJ, 11.7 ± 5.6 min and 89.5 ± 30.9 min, respectively. Most adverse events and complications were CTCAE grade 1 or 2 or SIR classification grade A or B. The 1-, 2-, and 3-year local tumor progression (LTP) rates were 65.9%, 31.5% and 18.5%, respectively, with a mean LTP of 19.216 months (95% CI: 16.208, 22.224); and the 1-, 2- and 3-year overall survival (OS) rates were 81.8%, 60.8% and 44.7%, respectively, with a mean OS of 26.378 months (95% CI: 23.485, 29.270). Multivariate Cox’s regression analysis further illustrated that tumor location (challenging locations vs ordinary locations) and the anesthesia (general anesthesia VS local anesthesia) were important factors affecting LTP and OS.

Conclusion

MR-guided MWA can successfully treat small hepatic metastases with potentially favorable safety and technical efficacy.

Diagnostic accuracy of Liver Imaging Reporting and Data System locoregional treatment response criteria: a systematic review and meta-analysis

OBJECTIVE

There is increasing adoption of Liver Imaging Reporting and Data System (LI-RADS) treatment response (LR-TR) criteria. However, there is still a relative lack of evidence evaluating the performance of these criteria. We performed this study to assess the diagnostic accuracy of LI-RADS LR-TR criteria.

METHODS

A thorough search of PubMed, Embase, Scopus, and Cochrane Central Register of Controlled Trials for studies reporting diagnostic accuracy of LI-RADS LR-TR criteria was conducted through 30 June 2020. The meta-analytic summary of sensitivity, specificity, and diagnostic odds ratio of LI-RADS LR-TR criteria was computed using explant histopathology as the reference standard. The quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

RESULTS

Four studies were found eligible for meta-analysis. The total number of LR-TR observations was 462 (240 patients, 82.5% males). Different locoregional therapies (LRTs), including bland embolization, chemoembolization, radiofrequency ablation, and microwave ablation, had been used. The mean time interval between LRT and liver transplantation ranged from 181 to 219 days. There was a moderate to good inter-reader agreement for LR-TR criteria. The pooled sensitivity and specificity of LR-TR criteria for viable disease were 62% (95% CI, 49-74%; I² = 69%) and 87% (95% CI, 76-93%; I² = 57%), respectively. The pooled diagnostic odds ratio and area under the curve were 9.83 (95% CI, 5.34-18.08; I² = 19%) and 0.80.

CONCLUSIONS

LI-RADS LR-TR criteria have acceptable diagnostic performance for the diagnosis of viable tumor after LRT. Well-designed prospective studies evaluating criteria of equivocal lesions and effect of different LRTs should be performed.

KEY POINTS

• The pooled sensitivity and specificity of LI-RADS LR-TR criteria for the diagnosis of viable tumor were 62% and 87%, respectively. • The pooled diagnostic odds ratio and area under the curve were 9.83 and 0.80. • LR-TR criteria had a moderate to good inter-reader agreement.

Predictors of Complete Response in Patients with Hepatocellular Carcinoma Treated with Trans-Arterial Radioembolization

Background: Trans-arterial radioembolization (TARE) has shown promising results in treating hepatocellular carcinoma (HCC). We identified independent predictors of radiological complete response (CR) in patients with intrahepatic HCC who were treated with TARE. Methods: Patients with intrahepatic HCC treated with TARE between 2011 and 2017 were recruited. CR was defined according to the modified Response Evaluation Criteria in Solid Tumors. Cox regression analysis was used to determine independent predictors of CR. Results: The median age of study participants (83 men and 19 women) was 64.3 years. The mean survival after TARE was 55.5 months, and 21 (20.6%) patients died during the study period. Patients who achieved CR (14 patients, 13.7%) had significantly higher serum albumin level (median 4.1 vs. 3.9 g/dL), lower total bilirubin level (median 0.6 vs. 0.7 mg/dL), lower aspartate aminotransferase level (median 30.0 vs. 43.0 IU/L), lower alkaline phosphatase level (median 79.0 vs. 103.0 IU/L), lower alpha-fetoprotein level (median 12.7 vs. 39.9 ng/mL), lower des-gamma-carboxyprothrombin level (median 575.5 vs. 2772.0 mAU/mL), lower model for end-stage liver disease (MELD) score (median 6.0 vs. 7.0), and smaller maximal tumor diameter (median 6.3 vs. 9.0 cm) compared to those who did not achieve CR (all p < 0.005). Multivariate Cox regression analysis showed that lower MELD score (hazard ratio (HR) = 0.436, p = 0.015) and maximal tumor size < 9 cm (HR = 11.180, p = 0.020) were independent predictors of an increased probability of radiological CR after TARE. Conclusions: Low MELD score and small maximal tumor size were independently associated with an increased probability of CR after TARE in patients with intrahepatic HCC.

Liver transplantation versus watchful waiting in hepatocellular carcinoma patients with complete response to bridging therapy - a retrospective observational study

Bridging therapy to prevent progression on the waiting list can result in a sustained complete response (sCR). In some patients, the liver transplantation (LT) risk might exceed those of tumor recurrence. We thus evaluated whether a watchful waiting (CR-WW) strategy could be a feasible alternative to transplantation (CR-LT). We performed a retrospective analysis of overall survival (OS) and recurrence-free survival (RFS) of patients with a sCR (CR > 6 months). Permitted bridging included thermoablation, resection, and combinations of either with transarterial chemoembolization. Patients were divided into the intended treatment strategies CR-WW and CR-LT. 39 (18.40%) sCR patients from 212 were investigated. 22 patients were treated with a CR-LT and 17 patients a CR-WW strategy. Five-year RFS was lower in the CR-WW than in the CR-LT group [53.3% (22.1%; 77.0%) and 84.0% (57.6%; 94.7%)]. 29.4% (5/17) CR-WW patients received salvage transplantation because of recurrence. OS (5-year) was 83.9% [56.8%; 94.7%] after LT and 75.4% [39.8%; 91.7%] after WW. Our analysis shows that the intuitive decision made by our patients in agreement with their treating physicians for a watchful waiting strategy in sCR can be justified. Applied on a larger scale, this strategy could help to reduce the pressure on the donor pool.

Consensus report from the 9th International Forum for Liver Magnetic Resonance Imaging: applications of gadoxetic acid-enhanced imaging

Objectives

The 9th International Forum for Liver Magnetic Resonance Imaging (MRI) was held in Singapore in September 2019, bringing together radiologists and allied specialists to discuss the latest developments in and formulate consensus statements for liver MRI, including the applications of gadoxetic acid–enhanced imaging.

Methods

As at previous Liver Forums, the meeting was held over 2 days. Presentations by the faculty on days 1 and 2 and breakout group discussions on day 1 were followed by delegate voting on consensus statements presented on day 2. Presentations and discussions centered on two main meeting themes relating to the use of gadoxetic acid–enhanced MRI in primary liver cancer and metastatic liver disease.

Results and conclusions

Gadoxetic acid–enhanced MRI offers the ability to monitor response to systemic therapy and to assist in pre-surgical/pre-interventional planning in liver metastases. In hepatocellular carcinoma, gadoxetic acid–enhanced MRI provides precise staging information for accurate treatment decision-making and follow-up post therapy. Gadoxetic acid–enhanced MRI also has potential, currently investigational, indications for the functional assessment of the liver and the biliary system. Additional voting sessions at the Liver Forum debated the role of multidisciplinary care in the management of patients with liver disease, evidence to support the use of abbreviated imaging protocols, and the importance of standardizing nomenclature in international guidelines in order to increase the sharing of scientific data and improve the communication between centers.

Key Points

• Gadoxetic acid–enhanced MRI is the preferred imaging method for pre-surgical or pre-interventional planning for liver metastases after systemic therapy.

• Gadoxetic acid–enhanced MRI provides accurate staging of HCC before and after treatment with locoregional/biologic therapies.

• Abbreviated protocols for gadoxetic acid–enhanced MRI offer potential time and cost savings, but more evidence is necessary. The use of gadoxetic acid–enhanced MRI for the assessment of liver and biliary function is under active investigation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-020-07637-4.

Early effect of 90Y radioembolisation on hepatocellular carcinoma and liver parenchyma stiffness measured with MR elastography: initial experience

OBJECTIVES

To quantify hepatocellular carcinoma (HCC) and liver parenchyma stiffness using MR elastography (MRE) and serum alpha fetoprotein (AFP), before and 6 weeks (6w) after ⁹⁰Y radioembolisation (RE), and to assess the value of baseline tumour and liver stiffness (TS/LS) and AFP in predicting response at 6w and 6 months (6 m).

METHODS

Twenty-three patients (M/F 18/5, mean age 68.3 ± 9.3 years) scheduled to undergo RE were recruited into this prospective single-centre study. Patients underwent an MRI exam at baseline and 6w following RE (range 39-47 days) which included MRE using a prototype 2D EPI sequence. TS, peritumoural LS/LS remote from the tumour, tumour size, and AFP were measured at baseline and at 6w. Treatment response was determined using mRECIST at 6w and 6 m.

RESULTS

MRE was technically successful in 17 tumours which were classified at 6w as complete response (CR, n = 7), partial response (PR, n = 4), and stable disease (SD, n = 6). TS and peritumoural LS were significantly increased following RE (p = 0.016, p = 0.039, respectively), while LS remote from tumour was unchanged (p = 0.245). Baseline TS was significantly lower in patients who achieved CR at 6w (p = 0.014). Baseline TS, peritumoural LS (both AUC = 0.857), and AFP (AUC = 0.798) showed fair/excellent diagnostic performance in predicting CR at 6w, but were not significant predictors of OR or CR at 6 m.

CONCLUSION

Our initial results suggest that HCC TS and peritumoural LS increase early after RE. Baseline TS, peritumoural LS, and AFP were all significant predictors of CR to RE at 6w. These results should be confirmed in a larger study.

KEY POINTS

• Magnetic resonance elastography-derived tumour stiffness and peritumoural liver stiffness increase significantly at 6 weeks post radioembolisation whereas liver stiffness remote from the tumour is unchanged. • Baseline tumour stiffness and peritumoural liver stiffness are lower in patients who achieve complete response at 6 weeks post radioembolisation. • Baseline tumour size is significantly correlated with baseline tumour stiffness.

Monitoring Response to Transarterial Chemoembolization in Hepatocellular Carcinoma Using 18F-Fluorothymidine PET

Accurate disease monitoring is essential after transarterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) because of the potential for profound adverse events and large variations in survival outcome. Posttreatment changes on conventional imaging can confound determination of residual or recurrent disease, magnifying the clinical challenge. On the basis of increased expression of thymidylate synthase (TYMS), thymidine kinase 1 (TK-1), and equilibrative nucleoside transporter 1 (SLC29A1) in HCC compared with liver tissue, we conducted a proof-of-concept study evaluating the efficacy of 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET to assess response to TACE. Because previous PET studies in HCC have been hampered by high background liver signal, we investigated whether a temporal-intensity voxel clustering (kinetic spatial filtering, or KSF) improved lesion detection. Methods: A tissue microarray was built from 36 HCC samples and from matching surrounding cirrhotic tissue and was stained for TK-1 A prospective study was conducted; 18 patients with a diagnosis of HCC by the criteria of the American Association for the Study of Liver Diseases who were eligible for treatment with TACE were enrolled. The patients underwent baseline conventional imaging and dynamic 18F-FLT PET with KSF followed by TACE. Imaging was repeated 6-8 wk after TACE. The PET parameters were compared with modified enhancement-based RECIST. Results: Cancer Genome Atlas analysis revealed increased RNA expression of TYMS, TK-1, and SLC29A1 in HCC. TK-1 protein expression was significantly higher in HCC (P < 0.05). The sensitivity of 18F-FLT PET for baseline HCC detection was 73% (SUVmax, 9.7 ± 3.0; tumor to liver ratio, 1.2 ± 0.3). Application of KSF did not improve lesion detection. Lesion response after TACE by modified RECIST was 58% (14 patients with 24 lesions). A 30% reduction in mean 18F-FLT PET uptake was observed after TACE, correlating with an observed PET response of 60% (15/25). A significant and profound reduction in the radiotracer delivery parameter K1 after TACE was observed. Conclusion:18F-FLT PET can differentiate HCC from surrounding cirrhotic tissue, with PET parameters correlating with TACE response. KSF did not improve visualization of tumor lesions. These findings warrant further investigation.

Critical review of HCC imaging in the multidisciplinary setting: treatment allocation and evaluation of response

Imaging has not only an established role in screening and diagnosis of hepatocellular carcinoma (HCC) in patients with chronic liver inflammatory diseases, but also a crucial importance for patient stratification and treatment allocation, as well as for assessing treatment response. In the setting of increasing therapeutic options for HCC, the Barcelona Clinic Liver Cancer (BCLC) system still remains the most appropriate way to select candidate cohorts for best treatments. This classification takes into account the imaging information on tumor burden and extension, liver function, and cancer-related symptoms, stratifying patients in five risk categories (Stages 0, A, B, C and D) associated with different treatment options. Still now, there are no clear roles for biomarkers use in treatment allocation. The increasing use of locoregional non-surgical therapies in the different stages is highly dependent on reliable evaluation of treatment response, in particular when they are used with curative intention or for downstaging at liver transplantation re-assessment. Moreover, objective response (OR) has emerged as an important imaging biomarker, providing information on tumor biology, which can contribute for further prognostic assessment. Current guidelines for OR assessment recommend only the measurement of viable tumor according to mRECIST criteria, with further classification into complete response, partial response, stable disease or progressive disease. Either computed tomography (CT) or magnetic resonance (MR) imaging can be used for this purpose, and the Liver Imaging Reporting and Data System (LI-RADS) committee has recently provided some guidance for reporting after locoregional therapies. Nevertheless, imaging pitfalls resulting from treatment-related changes can impact with the correct evaluation of treatment response, especially after transarterial radioembolization (TARE). Volume criteria and emerging imaging techniques might also contribute for a better refinement in the assessment of treatment response and monitoring. As the role of imaging deeply expands in the multidisciplinary assessment of HCC, our main objective in this review is to discuss state-of-the-art decision-making aspects for treatment allocation and provide guidance for treatment response evaluation.

Predictive Value of Early Response to Chemoradiotherapy in Advanced Esophageal Squamous Cell Carcinoma by Diffusion-Weighted MR Imaging

Objective:

To explore the value of diffusion-weighted imaging for early response detection of locally advanced esophageal squamous cell carcinoma with concurrent chemoradiotherapy.

Methods:

Fifty-five (42 males, 13 females) patients with locally advanced esophageal cancer who were undergoing chemoradiotherapy were recruited for this study. Diffusion-weighted imaging was performed in all patients before therapy, at the first weekend, the second weekend, and the end of chemoradiotherapy. The rate of change in apparent diffusion coefficient value and the maximum diameter between pretherapy and posttherapy were calculated.

Results:

Fifty-five patients with locally advanced esophageal squamous cell carcinoma were classified as responders (40 cases) and nonresponders (15 cases). Before chemoradiotherapy, the responders group had a significantly lower apparent diffusion coefficient values than the nonresponders group (t = −4.815, P = .000). At the 3 time points after chemoradiotherapy (first weekend, second weekend, and the end of chemoradiotherapy), there was no statistically significant difference in apparent diffusion coefficient values between responders and nonresponders (P > .05). The responders group had a significantly higher rate of change in apparent diffusion coefficient value than the nonresponders group at each time point (P < .05). At the first weekend of chemoradiotherapy, the rate of change in the maximum diameter was not significantly different in the 2 groups (t = 0.928, P = .357). There was a negative correlation between the tumor apparent diffusion coefficient value of pretherapy and the reduction ratio of tumor maximum diameter at the end of chemoradiotherapy (r = −0.592, P = .000).

Conclusions:

The change rate of apparent diffusion coefficient value by the end of the first week after beginning chemoradiotherapy may be a sensitive indicator to detect the early response to locally advanced esophageal squamous cell carcinoma.

Assessment of Hepatocellular Carcinoma Response to 90Y Radioembolization Using Dynamic Contrast Material-enhanced MRI and Intravoxel Incoherent Motion Diffusion-weighted Imaging

PURPOSE

To quantify diffusion and perfusion changes in hepatocellular carcinoma (HCC) induced by yttrium 90 (⁹⁰Y) radioembolization and to assess the value of dynamic contrast material-enhanced (DCE) MRI and intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for predicting HCC response.

MATERIALS AND METHODS

Institutional review board approval was obtained for this prospective study (clinical trial registry NCT01871545). Twenty-four participants with HCC (mean age, 69 years ± 9 [standard deviation], 18 men) underwent multiparametric MRI, including IVIM DWI and gadoxetic acid DCE MRI before (n = 24) and 6 weeks (n = 21) after radioembolization. IVIM DWI and DCE MRI histogram parameters were quantified in HCCs and liver parenchyma. HCC response was assessed by using modified Response Evaluation Criteria in Solid Tumors at 6 weeks and 6-12 months after radioembolization. Logistic regression analysis was used to evaluate the diagnostic performance of baseline MRI and clinical parameters for prediction of response.

RESULTS

Twenty-five HCCs were analyzed (mean size, 3.6 cm ± 1.9). Radioembolization resulted in significantly decreased perfusion (DCE MRI arterial flow, P = .002; IVIM pseudodiffusion coefficient [D*], P = .014). Multivariate logistic regression selected combined serum α-fetoprotein and portal flow (F _p ) skewness (area under the curve [AUC] = 0.924) and combined D* standard deviation and F _p kurtosis (AUC = 0.916) for prediction of objective and complete response at 6 weeks, respectively. Standard deviation of DCE MRI parameter arterial fraction was selected as the optimal predictor for complete response at 6-12 months (AUC = 0.857).

CONCLUSION

Diffusion and perfusion MRI can be used to evaluate the response of HCC to radioembolization. Pretreatment DCE MRI histogram parameters may be useful for radioembolization treatment stratification. Supplemental material is available for this article. © RSNA, 2020.

Transcatheter arterial chemoembolization alone or combined with ablation for recurrent intermediate-stage hepatocellular carcinoma: a propensity score matching study

PURPOSE

The recurrence after curative hepatectomy is common. Limited data have investigated the effect of transcatheter arterial chemoembolization (TACE) combined with ablation in treating recurrent intermediate-stage hepatocellular carcinoma (HCC) after hepatectomy. We aim to compare the efficacy of TACE combined with ablation versus TACE alone in treating recurrent intermediate-stage HCC after hepatectomy.

METHODS

A total of 183 patients with recurrent intermediate-stage HCC after hepatectomy were enrolled at Sun Yat-sen University Cancer Centre, including 111 patients who underwent TACE alone and 72 patients who underwent TACE combined with ablation (TACE-Ablation). Overall survival (OS) and progression-free survival (PFS) were compared by the log-rank test. Propensity score matching (PSM) was used to reduce the confounding bias.

RESULTS

Before PSM, the 5-year OS rates were 43.3% vs. 27.9% (P = 0.001), and the 5-year PFS rates were 21.7% vs. 13.0% (P < 0.001) for TACE-Ablation and TACE-alone groups, respectively. After PSM, TACE-Ablation still resulted in better 5-year OS (41.6% vs. 30.2%, P = 0.028) and 5-year PFS rate (21.3% vs. 15.8%, P = 0.024) than that of TACE alone. Patients in TACE-Ablation group exhibited similar major complication rates to TACE-alone group but higher minor complication rates both before and after PSM. Cox regression analysis identified TACE-alone modality as an independently unfavourable predictor for OS and PFS (both P < 0.05).

CONCLUSION

TACE combined with ablation is safe and superior to TACE alone in tumour control and prolonging overall survival in recurrent intermediate-stage HCC after hepatectomy.

A review of conventional and newer generation microwave ablation systems for hepatocellular carcinoma

Although microwave ablation (MWA) exhibits a high thermal efficiency, the major limitation of conventional MWA systems is the lack of predictability of the ablation zone size and shape. Therefore, a specific newer generation MWA system, The Emprint™ Ablation System with Thermosphere™ Technology, was designed to create predictable large spherical zones of ablation that are not impacted by varying tissue environments. The time required for ablation with MWA systems is short, and the shape of the necrosis is elliptical with the older systems and spherical with the new system. In addition, because MWA has no heat-sink effect, it can be used to ablate tumors adjacent to major vessels. Although these factors yield a large ablation volume and result in good local control, excessive ablation of liver tissue and unexpected ablation of surrounding organs are possible. Therefore, MWA should be carefully performed. This review highlights the efficacy and complications of MWA performed with conventional systems and the newer generation system in patients with hepatocellular carcinoma (HCC). MWA with the newer generation system seems to be a promising treatment option for large HCCs and secondary hepatic malignancies, with several advantages over other available ablation techniques, including conventional MWA. However, further randomized controlled trials are necessary to fully clarify the benefits and pitfalls of this new system.

Long-term outcomes of hepatocellular carcinoma that underwent chemoembolization for bridging or downstaging

BACKGROUND

Prospective study of 200 patients with hepatocellular carcinoma (HCC) that underwent liver transplant (LT) after drug-eluting beads transarterial chemoembolization (DEB-TACE) for downstaging versus bridging. Overall survival and tumor recurrence rates were calculated, eligibility for LT, time on the waiting list and radiological response were compared. After TACE, only patients within Milan Criteria (MC) were transplanted. More patients underwent LT in bridging group. Five-year post-transplant overall survival, recurrence-free survival has no difference between the groups. Complete response was observed more frequently in bridging group. Patients in DS group can achieve post-transplant survival and HCC recurrence-free probability, at five years, just like patients within MC in patients undergoing DEB-TACE.

AIM

To determine long-term outcomes of patients with HCC that underwent LT after DEB-TACE for downstaging vs bridging.

METHODS

Prospective cohort study of 200 patients included from April 2011 through June 2014. Bridging group included patients within MC. Downstaging group (out of MC) was divided in 5 subgroups (G1 to G5). Total tumor diameter was ≤ 8 cm for G1, 2, 3, 4 (n = 42) and was > 8 cm for G5 (n = 22). Downstaging (n = 64) and bridging (n = 136) populations were not significantly different. Overall survival and tumor recurrence rates were calculated by the Kaplan-Meier method. Additionally, eligibility for LT, time on the waiting list until LT and radiological response were compared.

RESULTS

After TACE, only patients within MC were transplanted. More patients underwent LT in bridging group 65.9% (P = 0.001). Downstaging population presented: higher number of nodules 2.81 (P = 0.001); larger total tumor diameter 8.09 (P = 0.001); multifocal HCC 78% (P = 0.001); more post-transplantation recurrence 25% (P = 0.02). Patients with maximal tumor diameter up to 7.05 cm were more likely to receive LT (P = 0.005). Median time on the waiting list was significantly longer in downstaging group 10.6 mo (P = 0.028). Five-year post-transplant overall survival was 73.5% in downstaging and 72.3% bridging groups (P = 0.31), and recurrence-free survival was 62.1% in downstaging and 74.8% bridging groups (P = 0.93). Radiological response: complete response was observed more frequently in bridging group (P = 0.004).

CONCLUSION

Tumors initially exceeding the MC down-staged after DEB-TACE, can achieve post-transplant survival and HCC recurrence-free probability, at five years, just like patients within MC in patients undergoing DEB-TACE.

Prognostic Relevance of a Complete Pathologic Response in Liver Transplantation for Hepatocellular Carcinoma

BACKGROUND

A complete pathologic response (CPR) after neoadjuvant treatment is reported to be associated with an exceptionally low risk of recurrence after liver transplantation for hepatocellular carcinoma (HCC). This study aimed to evaluate the prognostic role of CPR in liver transplantation for HCC.

METHODS

This retrospective cohort study was based on 222 HCC transplant recipients. Incidence of recurrence and survival at 5 years were the primary and secondary outcome measures, respectively. Competing risk analyses were applied to evaluate recurrence incidence and its predictors. Propensity score matching was performed to compare the outcomes for patients after neoadjuvant treatment with and without CPR.

RESULTS

Neoadjuvant treatment was performed for 127 patients, 32 of whom achieved CPR (25.2%). Comparison of baseline characteristics showed that the patients with CPR were at lowest baseline recurrence risk, followed by treatment-naïve patients and patients without CPR. Adjusted for potential confounders, CPR did not have any significant effects on tumor recurrence. No significant net reclassification improvement was noted after addition of CPR to existing criteria. Neoadjuvant treatment without CPR was associated with increased risk of recurrence in subgroups within the Milan criteria (p = 0.016), with alpha-fetoprotein concentration (AFP) model not exceeding 2 points (p = 0.021) and within the Warsaw criteria (p = 0.007) compared with treatment-naïve patients who were at risk similar to those with CPR. The 5-year incidences of recurrence in propensity score-matched patients with and without CPR were respectively 14.0% and 15.9% (p = 0.661), with corresponding survival rates of 73.2% and 67.4%, respectively (p = 0.329).

CONCLUSIONS

The findings showed that CPR is not independently associated with long-term outcomes after liver transplantation for HCC.

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.

Recent advances in liver transplantation for cancer: The future of transplant oncology

Liver transplantation is widely indicated as a curative treatment for selected patients with hepatocellular carcinoma. However, with recent therapeutic advances, as well as efforts to increase the donor pool, liver transplantation has been carefully expanded to patients with other primary or secondary malignancies in the liver. Cholangiocarcinoma, colorectal and neuroendocrine liver metastases, and hepatic epithelioid haemangioendothelioma are amongst the most relevant new indications. In this review we discuss the fundamental concepts of this ambitious undertaking, as well as the newest indications for liver transplantation, with a special focus on future perspectives within the recently established concept of transplant oncology.

Prediction of hepatocellular carcinoma response to 90Yttrium radioembolization using volumetric ADC histogram quantification: preliminary results

Purpose

To assess the predictive value of volumetric apparent diffusion coefficient (vADC) histogram quantification obtained before and 6 weeks (6w) post-treatment for assessment of hepatocellular carcinoma (HCC) response to ⁹⁰Yttrium radioembolization (RE).

Methods

In this retrospective study, 22 patients (M/F 15/7, mean age 65y) who underwent lobar RE were included between October 2013 and November 2014. All patients underwent routine liver MRI pre-treatment and 6w after RE. Two readers assessed index tumor response at 6 months after RE in consensus, using mRECIST criteria. vADC histogram parameters of index tumors at baseline and 6w, and changes in vADC (ΔvADC) histogram parameters were calculated. The predictive value of ADC metrics was assessed by logistic regression with stepwise parameter selection and ROC analyses.

Results

Twenty two HCC lesions (mean size 3.9 ± 2.9 cm, range 1.2–12.3 cm) were assessed. Response at 6 months was as follows: complete response (CR, n = 6), partial response (PR, n = 3), stable disease (SD, n = 12) and progression (PD, n = 1). vADC median/mode at 6w (1.81–1.82 vs. 1.29–1.35 × 10^− 3 mm²/s) and ΔvADC median/max (27–44% vs. 0–10%) were significantly higher in CR/PR vs. SD/PD (p = 0.011–0.036), while there was no significant difference at baseline. Logistic regression identified vADC median at 6w as an independent predictor of response (CR/PR) with odds ratio (OR) of 3.304 (95% CI: 1.099–9.928, p = 0.033) and AUC of 0.77. ΔvADC mean was identified as an independent predictor of CR with OR of 4.153 (95%CI: 1.229–14.031, p = 0.022) and AUC of 0.91.

Conclusion

Diffusion histogram parameters obtained at 6w and early changes in ADC from baseline are predictive of subsequent response of HCCs treated with RE, while pre-treatment vADC histogram parameters are not. These results need confirmation in a larger study.

Trial registration

This retrospective study was IRB-approved and the requirement for informed consent was waived.

The mRECIST Classification Provides Insight into Tumor Biology for Patients With Hepatocellular Carcinoma Awaiting Liver Transplantation

With recent changes in United Network for Organ Sharing policy, patients in the United States with hepatocellular carcinoma (HCC) are likely to spend more time on the liver transplantation (LT) waiting list. The increasing wait time will allow for an opportunity to assess tumor biology prior to LT. Modified Response Evaluation Criteria in Solid Tumors (mRECIST) paradigm provides such a framework for this assessment, and yet little is understood of its utility as it would apply for patients listed for LT in the United States. Through a collaboration between the University of California, San Francisco, and the Mayo Clinic, Jacksonville, Florida, the experience of 772 patients listed for LT were retrospectively reviewed to study the impact of immediate mRECIST classification following locoregional therapy (LRT) on pre- and post-LT outcomes. Patients who had progression of disease (PD; n = 72), failed to respond to LRT (n = 89) at any time point, or did not achieve radiologic complete response (CR; n = 224) were all at significant risk for wait-list dropout (odds ratio [OR] = 12.11, 4.81, and 2.48; respectively). CR identified a cohort of patients who were at a reduced risk for wait-list dropout. However, 24.9% eventually required further intervention while waiting for transplant, and as many as 82.4% were found to have residual HCC on explant pathology. Failure to respond to LRT was associated with increased risk for recurrence (OR = 3.00) more so than PD (OR = 1.36), suggesting that despite PD, patients who eventually can respond to LRT may represent favorable candidates for LT. In conclusion, for patients awaiting LT, the mRECIST assessment provides critical guidance for patient management. Although PD portends a poor prognosis, our findings suggest that further aggressive LRT should be pursued because a response to LRT may yield acceptable results for patients awaiting LT as well as after LT.

Assessment of Radiofrequency Ablation Efficacy for Hepatocellular Carcinoma by Histology and Pretransplant Radiology

Radiofrequency ablation (RFA) represents a potentially curative option for early-stage hepatocellular carcinoma (HCC). This study aims at evaluating the histologic response after RFA of small HCCs arising in cirrhosis. Data were reviewed from 78 patients with de novo HCCs who were treated with RFA and subsequently transplanted. The last radiological assessment before liver transplantation (LT) was used for comparison between modified Response Evaluation Criteria in Solid Tumors (mRECIST) and histological findings. A total of 125 de novo HCCs (median diameter, 20 mm) were treated with RFA only in 92 sessions. There were 98 nodules that did not show local recurrence during follow-up (78.4%), and the remaining were retreated, except 1 because of subsequent LT. On explanted livers, complete pathological response (CPR) was observed in 61.6%, being 76.9% when <2 cm, 55.0% when 2-3 cm, and 30.8% when >3 cm. Tumors near hepatic vessels had CPR in 50% of patients versus 69.3% for tumors distant from vessels (P = 0.039). Of the 125 HCCs, 114 had available radiological assessment within a median of 3 months before LT. Complete radiological response, according to mRECIST, was observed in 77.2% of nodules before LT. The Cohen κ was 0.48 (moderate agreement). The overall accuracy was 78.1%. A total of 18 complications were recorded with only 1 graded as major. In conclusion, RFA can provide high CPR for HCC, especially in smaller tumors distant from hepatic veins or portal branches. The agreement between mRECIST and histology is only moderate. Further refinements in radiological assessment are essential to accurately assess the true effectiveness of RFA.

Histogram analysis of apparent diffusion coefficient predicts response to radiofrequency ablation in hepatocellular carcinoma

Objective

The aim of this study was to predict tumor progression in patients with hepatocellular carcinoma (HCC) treated with radiofrequency ablation (RFA) using histogram analysis of apparent diffusion coefficients (ADC).

Methods

Breath-hold diffusion weighted imaging (DWI) was performed in 64 patients (33 progressive and 31 stable) with biopsy-proven HCC prior to RFA. All patients had pre-treatment magnetic resonance imaging (MRI) and follow-up computed tomography (CT) or MRI. The ADC values (ADC₁₀, ADC₃₀, ADC_median and ADC_max) were obtained from the histogram’s 10th, 30th, 50th and 100th percentiles. The ratios of ADC₁₀, ADC₃₀, ADC_median and ADC_max to the mean non-lesion area-ADC (RADC₁₀, RADC₃₀, RADC_median, and RADC_max) were calculated. The two patient groups were compared. Key predictive factors for survival were determined using the univariate and multivariate analysis of the Cox model. The Kaplan-Meier survival analysis was performed, and pairs of survival curves based on the key factors were compared using the log-rank test.

Results

The ADC₃₀, ADC_median, ADC_max, RADC₃₀, RADC_median, and RADC_max were significantly larger in the progressive group than in the stable group (P<0.05). The median progression-free survival (PFS) was 22.9 months for all patients. The mean PFS for the stable and progressive groups were 47.7±1.3 and 9.8±1.3 months, respectively. Univariate analysis indicated that RADC₁₀, RADC₃₀, and RADC_median were significantly correlated with the PFS [hazard ratio (HR)=31.02, 43.84, and 44.29, respectively, P<0.05 for all]. Multivariate analysis showed that RADC_median was the only independent predictor of tumor progression (P=0.04). And the cutoff value of RADC_median was 0.71.

Conclusions

Pre-RFA ADC histogram analysis might serve as a useful biomarker for predicting tumor progression and survival in patients with HCC treated with RFA.

Mapping Drug Dose Distribution on CT Images Following Transarterial Chemoembolization with Radiopaque Drug-Eluting Beads in a Rabbit Tumor Model

Purpose To correlate bead location and attenuation on CT images with the quantity and distribution of drug delivered to the liver following transarterial chemoembolization (TACE) with radiopaque drug-eluting beads (DEB) in a rabbit tumor model. Materials and Methods All procedures were performed with a protocol approved by the Institutional Animal Care and Use Committee. TACE was performed in rabbits (n = 4) bearing VX2 liver tumors by using radiopaque DEB (70-150 µm) loaded with doxorubicin (DOX). Livers were resected 1 hour after embolization, immediately frozen, and cut by using liver-specific three-dimensional-printed molds for colocalization of liver specimens and CT imaging. DOX penetration into tissue surrounding beads was evaluated with fluorescence microscopy. DOX levels in liver specimens were predicted by using statistical models correlating DOX content measured in tissue with bead volume and attenuation measured on CT images. Model predictions were then compared with actual measured DOX concentrations to assess the models' predictive power. Results Eluted DOX remained in close proximity (<600 µm) to beads in the liver 1 hour after TACE. Bead volume and attenuation measured on CT images demonstrated positive linear correlations (0.950 and 0.965, respectively) with DOX content in liver specimens. DOX content model predictions based on CT images were accurate compared with actual liver DOX levels at 1 hour. Conclusion CT may be used to estimate drug dose delivery and distribution in the liver following transarterial chemoembolization (TACE) with doxorubicin-loaded radiopaque drug-eluting beads (DEB). Although speculative, this informational map might be helpful in planning and understanding the spatial effects of TACE with DEB. © RSNA, 2018.