18F-FDG PET in Liver Transplantation Setting of Hepatocellular Carcinoma: Predicting Histology?

The potential of 18F-FDG PET/CT metabolic parameter-based nomogram in predicting the microvascular invasion of hepatocellular carcinoma before liver transplantation

PURPOSE

Microvascular invasion (MVI) is a critical factor in predicting the recurrence and prognosis of hepatocellular carcinoma (HCC) after liver transplantation (LT). However, there is a lack of reliable preoperative predictors for MVI. The purpose of this study is to evaluate the potential of an 18F-FDG PET/CT-based nomogram in predicting MVI before LT for HCC.

METHODS

83 HCC patients who obtained 18F-FDG PET/CT before LT were included in this retrospective research. To determine the parameters connected to MVI and to create a nomogram for MVI prediction, respectively, Logistic and Cox regression models were applied. Analyses of the calibration curve and receiver operating characteristic (ROC) curves were used to assess the model's capability to differentiate between clinical factors and metabolic data from PET/CT images.

RESULTS

Among the 83 patients analyzed, 41% were diagnosed with histologic MVI. Multivariate logistic regression analysis revealed that Child-Pugh stage, alpha-fetoprotein, number of tumors, CT Dmax, and Tumor-to-normal liver uptake ratio (TLR) were significant predictors of MVI. A nomogram was constructed using these predictors, which demonstrated strong calibration with a close agreement between predicted and actual MVI probabilities. The nomogram also showed excellent differentiation with an AUC of 0.965 (95% CI 0.925-1.000).

CONCLUSION

The nomogram based on 18F-FDG PET/CT metabolic characteristics is a reliable preoperative imaging biomarker for predicting MVI in HCC patients before undergoing LT. It has demonstrated excellent efficacy and high clinical applicability.

Predictive Value of Preoperative 18 Fludeoxyglucose Positron Emission Tomography-Computed Tomography for Survival in Liver Transplantation Due to Hepatocellular Cancer

BACKGROUND

We aimed to study the predictive value of preoperative perform [18F] Fludeoxyglucose positron emission tomography-computed tomography ([18] FDG PET-CT) for survival in liver transplantation due to hepatocellular cancer.

METHODS

Ninety-six patients who underwent liver transplantation for hepatocellular cancer (HCC) after preoperative PET-CT evaluation were examined for the study. All patients' ages, genders, body mass index, blood groups, Child-Pugh and Model for End-Stage Liver Disease scores, etiologies, median Alpha Fetoprotein values, Milan Criteria and T stages, grades, macrovascular and microvascular invasions, multicentricities, maximum and total tumor sizes, tumor number findings in explant specimens, and recurrence rates were analyzed statistically.

RESULTS

Statistically, microvascular (P = .002) and macrovascular invasions (P = .034) were observed more frequently in patients who are PET-CT (+) compared with patients who are PET-CT (-). PET-CT positivity was associated with shortened disease-free survival (DFS) statistically (P = .004).

CONCLUSION

Positron emission tomography-CT positivity may be important for predicting prognostic markers such as DFS and vascular invasion in the preoperative evaluation. Before transplantation, PET-CT should be applied to all patients with HCC.

Impact of metabolic indices of 18F-fluorodeoxyglucose positron emission tomography/computed tomography on post transplantation recurrence of hepatocellular carcinoma

BACKGROUND

Tumor recurrence is the leading cause of death after liver transplantation in patients with hepatocellular carcinoma. There is an ongoing debate as to whether metabolic indices such as tumor to liver standardized uptake value ratio in ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography of the primary tumor can identify patients outside the Milan criteria with as low recurrence rates as patients inside Milan and thus should be added to the established prognostic factors.

METHODS

This retrospective study analyzes 103 consecutive patients who underwent ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography before liver transplantation for hepatocellular carcinoma using data of clinical tumor registry. Primary endpoints were overall survival and 10-year cumulative recurrence rates.

RESULTS

Tumor to liver standardized uptake value ratio of the primary tumor was statistically significant higher in Milan out tumors, "up-to-seven" out tumors, grade 3 tumors, α- fetoprotein level >400 ng/ml and lesions > 5cm in diameter. Factors with statistically significant influence on the 10- year overall survival in the univariate analysis were Milan, up-to-seven" criteria, number of lesions and pT-category. COX regression analysis did not show independently statistically significant factors for 10-year overall survival. Milan, "up-to-seven" criteria, grade, pV, number of lesions, size of lesion, pT-category, tumor to liver standardized uptake value ratio influenced 10-year cumulative recurrence rates statistically significant. Tumor to liver standardized uptake value ratio, grade and pT-category proved to be independently statistically significant factors for 10-year cumulative recurrence rates.

CONCLUSIONS

Our study suggests that tumor to liver standardized uptake value standardized uptake value ratio in ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography is an independent prognostic factor in transplanted patients with hepatocellular carcinoma. If we focus on preoperative findings, such as tumor size, tumor number and AFP value adding the information given by TLR of ¹⁸F-FDG PET/CT allows to estimate the risk of tumor recurrence more accurate than the established classifications Milan and UTS. Therefore, it may add valuable information to other preoperative findings, such as tumor size, tumor number and AFP level.

Preoperative clinical-radiomics nomogram for microvascular invasion prediction in hepatocellular carcinoma using [Formula: see text]F-FDG PET/CT

PURPOSE

To develop a clinical-radiomics nomogram by incorporating radiomics score and clinical predictors for preoperative prediction of microvascular invasion in hepatocellular carcinoma.

METHODS

A total of 97 HCC patients were retrospectively enrolled from Shanghai Universal Medical Imaging Diagnostic Center and Changhai Hospital Affiliated to the Second Military Medical University. 909 CT and 909 PET slicers from 97 HCC patients were divided into a training cohort (N = 637) and a validation cohort (N = 272). Radiomics features were extracted from each CT or PET slicer, and features selection was performed with least absolute shrinkage and selection operator regression and radiomics score was also generated. The clinical-radiomics nomogram was established by integrating radiomics score and clinical predictors, and the performance of the models were evaluated from its discrimination ability, calibration ability, and clinical usefulness.

RESULTS

The radiomics score consisted of 45 selected features, and age, the ratio of maximum to minimum tumor diameter, and [Formula: see text]F-FDG uptake status were independent predictors of microvascular invasion. The clinical-radiomics nomogram showed better performance for MVI detection (0.890 [0.854, 0.927]) than the clinical nomogram (0.849 [0.804, 0.893]) ([Formula: see text]). Both nomograms showed good calibration and the clinical-radiomics nomogram's clinical practicability outperformed the clinical nomogram.

CONCLUSIONS

With the combination of radiomics score and clinical predictors, the clinical-radiomics nomogram can significantly improve the predictive efficacy of microvascular invasion in hepatocellular carcinoma ([Formula: see text]) compared with clinical nomogram.

Liver Transplantation for Hepatocellular Carcinoma: How Should We Improve the Thresholds?

Simple Summary

The ideal treatment for hepatocellular carcinoma (HCC) is liver transplantation (LT), which both eliminates the HCC and cures the diseased liver. Once considered an experimental treatment with dismal survival rates, LT for HCC entered a new era with the establishment of the Milan criteria over 20 years ago. However, over the last two decades, the Milan criteria, which are based on tumor morphology, have come under intense scrutiny and are now largely regarded as too restrictive, and limit the access of transplantation for many patients who would otherwise achieve good clinical outcomes. The liver transplant community has been making every effort to reach a goal of establishing more reliable selection criteria. This article addresses how the criteria have been extended, as well as the concept of pre-transplant down-staging to maximize the eligibility.

Abstract

Hepatocellular carcinoma (HCC) is the third highest cause of cancer-related mortality, and liver transplantation is the ideal treatment for this disease. The Milan criteria provided the opportunity for HCC patients to undergo LT with favorable outcomes and have been the international gold standard and benchmark. With the accumulation of data, however, the Milan criteria are not regarded as too restrictive. After the implementation of the Milan criteria, many extended criteria have been proposed, which increases the limitations regarding the morphological tumor burden, and incorporates the tumor’s biological behavior using surrogate markers. The paradigm for the patient selection for LT appears to be shifting from morphologic criteria to a combination of biologic, histologic, and morphologic criteria, and to the establishment of a model for predicting post-transplant recurrence and outcomes. This review article aims to characterize the various patient selection criteria for LT, with reference to several surrogate markers for the biological behavior of HCC (e.g., AFP, PIVKA-II, NLR, 18F-FDG PET/CT, liquid biopsy), and the response to locoregional therapy. Furthermore, the allocation rules in each country and the present evidence on the role of down-staging large tumors are addressed.

18F-FDG-PET/CT Imaging for Gastrointestinal Malignancies

Gastrointestinal malignancies encompass a variety of primary tumor sites, each with different staging criteria and treatment approaches. In this review we discuss technical aspects of 18F-FDG-PET/CT scanning to optimize information from both the PET and computed tomography components. Specific applications for 18F-FDG-PET/CT are summarized for initial staging and follow-up of the major disease sites, including esophagus, stomach, hepatobiliary system, pancreas, colon, rectum, and anus.

Diagnostic test accuracies of F-18 FDG PET/CT for prediction of microvascular invasion of hepatocellular carcinoma: A meta-analysis

PURPOSE

The aim of the current meta-analysis was to evaluate diagnostic accuracies of preoperative F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) or positron emission tomography/computed tomography (PET/CT) for prediction of microvascular invasion (MVI) in hepatocellular carcinoma (HCC) patients.

METHODS

The scientific database such as PubMed, Cochrane, and Embase database were searched for studies evaluating diagnostic accuracies of preoperative F-18 FDG PET or PET/CT for prediction of MVI in HCC patients up to November 30, 2020.

RESULTS

Fourteen eligible studies (1276 patients) were enrolled. The pooled sensitivity for F-18 FDG PET or PET/CT was 0.67 (95% CI; 0.57-0.76) with heterogeneity and a pooled specificity of 0.80 (95% CI; 0.74-0.85) with heterogeneity. Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 3.3 (95% CI; 2.5-4.5) and negative likelihood ratio (LR-) of 0.41 (95% CI; 0.31-0.55). The pooled diagnostic odds ratio (DOR) was 8 (95% CI; 5-14). Summary receiver operating characteristic (ROC) curve indicates that the area under the curve was 0.81 (95% CI; 0.78-0.84).

CONCLUSION

The current meta-analysis showed a low sensitivity and moderate specificity of F-18 FDG PET or PET/CT for the prediction of MVI in HCC patients. F-18 FDG PET or PET/CT might not be useful for the preoperative prediction of MVI in HCC patients and should not be used to exclude MVI. Therefore, cautious application and interpretation should be paid to the F-18 FDG PET or PET/CT for the prediction of MVI in HCC patients preoperatively.

Investigating the value of pre-treatment 18F-FDG PET/CT in predicting the pathological characteristic of hepatocellular carcinoma and recurrence after liver transplantation

PURPOSE

The aim of this study is to investigate the value of pre-treatment ¹⁸F-FDG PET/CT in predicting the pathological characteristic of HCC and recurrence after liver transplantation (LT).

METHODS

A total of 34 patients who underwent ¹⁸F-FDG PET/CT before LT for HCC and did not receive any other treatment were retrospectively enrolled in the study. The maximal standard uptake value of the tumor (T-SUVmax), normal liver tissues (L-SUVmax), and mediastinal blood pool (B-SUVmax) were derived, followed by the calculations of the T-SUVmax/L-SUVmax (T/L) and the T-SUVmax/B-SUVmax (T/B) ratios. Combined with the post-transplantation pathological results and ROC curve, the performance in predicting the pathological characteristic and the recurrence after LT were evaluated.

RESULTS

The AUCs for T-SUVmax, T/L, and T/B in predicting the pathological grade of tumors were 0.820, 0.784, and 0.806, respectively. Alternatively, the AUCs for T-SUVmax, T/L, and T/B in predicting the recurrence after LT were 0.865, 0.899, and 0.931, respectively. The individual cutoff values were 5.0, 1.7, and 2.2, corresponding to a predication accuracy of 88.2%, 85.3%, and 88.2%, respectively. In addition, the AUCs for T/B in predicting microvascular invasion (mVI) and liver capsular invasion (LCI) were 0.825 and 0.788, respectively.

CONCLUSION

The pre-treatment ¹⁸F-FDG PET/CT is effective for predicting recurrence of HCC after LT. In addition, it demonstrates values for predicting the pathological characteristic of HCC such as pathological grade, mVI, and LCI.

2-[18F]FDG PET/CT as a Predictor of Microvascular Invasion and High Histological Grade in Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) generally presents a low avidity for 2-deoxy-2-[18F]fluoro-d-glucose (FDG) in PET/CT although an increased FDG uptake seems to relate to more aggressive biological factors. To define the prognostic value of PET/CT with FDG in patients with an HCC scheduled for a tumor resection, forty-one patients were prospectively studied. The histological factors of a poor prognosis were determined and FDG uptake in the HCC lesions was analyzed semi-quantitatively (lean body mass-corrected standardized uptake value (SUL) and tumor-to-liver ratio (TLR) at different time points). The PET metabolic parameters were related to the histological characteristics of the resected tumors and to the evolution of patients. Microvascular invasion (MVI) and a poor grade of differentiation were significantly related to a worse prognosis. The SULpeak of the lesion 60 min post-FDG injection was the best parameter to predict MVI while the SULpeak of the TLR at 60 min was better for a poor differentiation. Moreover, the latter parameter was also the best preoperative variable available to predict any of these two histological factors. Patients with an increased TLRpeak60 presented a significantly higher incidence of poor prognostic factors than the rest (75% vs. 28.6%, p = 0.005) and a significantly higher incidence of recurrence at 12 months (38% vs. 0%, p = 0.014). Therefore, a semi-quantitative analysis of certain metabolic parameters on PET/CT can help identify, preoperatively, patients with histological factors of a poor prognosis, allowing an adjustment of the therapeutic strategy for those patients with a higher risk of an early recurrence.

Incorporating Tumor Biology to Predict Hepatocellular Carcinoma Recurrence in Patients Undergoing Living Donor Liver Transplantation Using Expanded Selection Criteria

Conventional selection criteria for liver transplantation (LT) in patients with hepatocellular carcinoma (HCC) are based on tumour size/number only, and do not consider vital surrogates of tumor biology such as alpha-fetoprotein (AFP) and tumor [¹⁸ F]fluorodeoxyglucose positron emission tomography ([¹⁸ F]FDG PET) avidity. We analyzed survival outcomes, and predictors of HCC recurrence in 405 patients with cirrhosis and HCC (HCC-cirr) who underwent living donor LT (LDLT) using our expanded selection criteria: no extrahepatic disease or major vascular invasion, irrespective of tumor size/number. Fifty-one percent patients had tumours beyond Milan, and 43% beyond the University of California San Francisco [UCSF] criteria. The 5-year overall survival (OS) and recurrence-free survival (RFS) were 64% and 70%, respectively. Three preoperatively available factors predicted recurrence: pre-LT AFP ≥100 ng/mL (P = 0.005; hazard ratio [HR], 2.190), tumor burden beyond the UCSF criteria (P = 0.001; HR, 2.640), and [¹⁸ F]FDG PET avidity (P = 0.004; HR, 2.442). A prognostic model based on the number and combination of the aforementioned preoperative risk factors was developed using a competing-risk RFS model. Three risk groups were identified: low (none or a single risk factor present, 9.3% recurrence), moderate (AFP ≥100 ng/mL and [¹⁸ F]FDG PET avidity, or beyond UCSF tumor and [¹⁸ F]FDG PET avidity, 25% recurrence), and high (AFP ≥100 ng/mL and beyond UCSF, or presence of all 3 risk factors, 46% recurrence). Acceptable long-term outcomes were achieved using our expanded selection criteria. Our prognostic model to predict recurrence based on preoperative biological and morphological factors could guide pretransplant management (downstaging versus upfront LDLT) with the aim of reducing post-LDLT recurrence.

18F-fludeoxyglucose positron emission tomography for diagnosis of HCC: implications for therapeutic strategy in curative and non-curative approaches

Hepatocellular carcinoma (HCC) is a global health issue with increasing incidence and high mortality rate. Depending on the tumor load and extent of underlying liver cirrhosis, aggressive surgical treatment by hepatectomy or liver transplantation (LT) may lead to cure, whereas different modalities of liver-directed locoregional or systemic tumor treatments are currently available for a noncurative approach. Apart from tumor burden and grade of liver dysfunction, assessment of prognostic relevant biological tumor aggressiveness is vitally important for establishing a promising multimodal therapeutic strategy and improving the individual treatment-related risk/benefit ratio. In recent years, an increasing body of clinical evidence has been presented that ¹⁸F-fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET), which is a standard nuclear imaging device in oncology, may serve as a powerful surrogate for tumor invasiveness and prognosis in HCC patients and, thereby, impact individual decision making on most appropriate therapy concept. This review describes the currently available data on the prognostic value of ¹⁸F-FDG PET in patients with early and advanced HCC stages and the resulting implications for treatment strategy.

Role of pre-transplant 18F-FDG PET/CT in predicting hepatocellular carcinoma recurrence after liver transplantation

The last two decades have seen a paradigm shift in the selection of patients with hepatocellular carcinoma (HCC) for liver transplantation. Microvascular invasion and differentiation have been the most significant factors affecting post-transplant recurrence; however, because of inherent disadvantages of pre-transplant biopsy, histological criteria never gained popularity. Recently, the selection criteria evolved from morphological to biological criteria, such as biomarkers and response to loco-regional therapy. With the introduction of multimodality imaging, combination of computed tomography with nuclear medicine imaging, particularly, 18F-fluorodeoxyglucose positron emission tomography fulfilled an unmet need and rapidly became a critical component of HCC management. This review article will focus on the use of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in the pre-transplant evaluation of HCC patients with special discussion on its ability to predict HCC recurrence after liver transplantation.

The Clinical Implications of Liver Resection Margin Size in Patients with Hepatocellular Carcinoma in Terms of Positron Emission Tomography Positivity

BACKGROUND

The positivity of positron emission tomography (PET) in hepatocellular carcinoma (HCC) correlates with aggressive tumor factors and poor survival. Adequate resection margin size is still a topic of debate. We analyzed the clinical implications of resection margin size in patients with HCC in terms of PET positivity.

METHODS

We retrospectively reviewed the medical records of 92 patients who underwent liver resection from March 2012 to October 2015. We investigated prognostic factors for recurrence and survival. We analyzed the correlation of resection margin size and PET positivity. Resection margins were classified as less than 1 cm and more than 1 cm.

RESULTS

Twenty six (31.3%) patients had PET-positive HCC. Multivariate analysis showed PET, satellite nodules, microvessel invasion, and multicentric occurrence were significant prognostic factors for HCC recurrence. Multivariate analysis also showed satellite nodules and microscopic portal vein invasion were significant prognostic factors for overall survival (OS). Resection margin size did not affect disease-free survival (DFS) (p = 0.681) or OS (p = 0.301) in patients with PET-negative HCC, but showed a difference in DFS [<1 cm at 11 months vs. ≥1 cm at 41 months (p = 0.188)] and OS [<1 cm at 28 months vs. ≥1 cm at 48 months (p < 0.001)] in patients with PET-positive HCC.

CONCLUSIONS

PET has low sensitivity for HCC. However, it is useful to predict treatment outcomes after liver resection or liver transplantation for HCC. Although the extent of liver resection must be decided based on liver function, a resection margin size >1 cm may improve DFS and OS in patients with PET-positive HCC.

Efficacy of contrast-enhanced FDG PET/CT in patients awaiting liver transplantation with rising alpha-fetoprotein after bridge therapy of hepatocellular carcinoma

OBJECTIVE

To assess the diagnostic accuracy and illustrate positive findings of contrast-enhanced fluorine-18 fluoro-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) image in patients awaiting liver transplantation (LT) with rising alpha-fetoprotein (AFP) after bridge therapy of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This prospective study included 100 patients who were waiting for LT and who previously underwent locoregional therapy (LRT) of HCC. These patients had rising AFP levels on a routine follow-up examination awaiting LT. All patients underwent a contrast-enhanced ¹⁸F-FDG PET/CT examination. We calculated for each patient the maximum standardised uptake value (SUVmax) of the tumour and the ratio of the tumoral SUVmax to the normal-liver SUVmax. The diagnostic accuracy and positive contrast-enhanced findings of ¹⁸F-FDG PET/CT were established by histopathology and clinical and imaging follow-up as the reference standards.

RESULTS

Contrast-enhanced ¹⁸F-FDG PET/CT detected tumour relapse in 78 patients (13 patients had intrahepatic lesions, 10 patients had extrahepatic metastases and 55 patients with combined lesions). The sensitivity, specificity and accuracy values of contrast-enhanced ¹⁸F-FDG PET/CT examination in the detection of HCC recurrence were 92.8%, 94.1% and 93%, respectively. A significant correlation was found between the AFP level and SUVmax ratio (r = 0.2283; p = 0.0224). The best threshold for ¹⁸F-FDG PET positivity was >1.21.

CONCLUSION

Contrast-enhanced ¹⁸F-FDG PET/CT is a valuable tool for the detection of intrahepatic HCC recurrence or extrahepatic metastasis following rising AFP levels after LRT of HCC, and should be incorporated during routine workup awaiting LT.

KEY POINTS

• ¹⁸F-FDG PET/CT is a valuable tool for the detection of HCC recurrence • ¹⁸ F-FDG PET/CT should be incorporated during routine workup awaiting liver transplantation • Significant correlation was found between AFP level and SUVmax ratio • The best threshold for ¹⁸ F-FDG PET positivity was >1.21 • The ideal cut-off value for AFP was >202.

Combining 18F-FDG positron emission tomography with Up-to-seven criteria for selecting suitable liver transplant patients with advanced hepatocellular carcinoma

The Up-to-seven (UTS) criteria (sum of tumor size and number not exceeding 7) for indicating liver transplantation (LT) in hepatocellular carcinoma (HCC) were originally based on explant pathology features and absence of microvascular invasion (MVI). ¹⁸F-fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) was shown to indicate the risk of MVI and tumor recurrence. The aim of this study was to analyze the prognostic significance of the clinical UTS criteria when being combined with PET-status of the tumor. Data of 116 liver transplant patients were subject to retrospective analysis. Five-year recurrence-free survival (RFS) rates in patients meeting (n = 85) and exceeding (n = 21) the radiographic UTS criteria were 81% and 55.1%, respectively (p = 0.014). In the UTS In subset, RFS was significantly better in PET-negative (94.9%) than in PET-positive patients (48.3%; p < 0.001). In the UTS Out subset, 5-year RFS rates were 87.1% and 19% in patients with non- ¹⁸F-FDG-avid and ¹⁸F-FDG-avid tumors (p < 0.001), respectively. Positive PET-status was identified as the only independent clinical predictor of tumor recurrence in beyond UTS patients (Hazard ratio [HR] 19.25; p < 0.001). Combining radiographic UTS criteria with FDG-PET may safely expand the HCC selection criteria for LT.

The value of [11C]-acetate PET and [18F]-FDG PET in hepatocellular carcinoma before and after treatment with transarterial chemoembolization and bevacizumab

Purpose

This prospective study was to investigate the value of [¹¹C]-acetate PET and [¹⁸F]-FDG PET in the evaluation of hepatocellular carcinoma (HCC) before and after treatment with transarterial chemoembolization (TACE) and vascular endothelial growth factor (VEGF) antibody (bevacizumab).

Methods

Twenty-two patients (three women, 19 men; 62 ± 8 years) with HCC verified by histopathology were treated with TACE and bevacizumab (n = 11) or placebo (n = 11). [¹¹C]-acetate PET and [¹⁸F]-FDG PET were performed before and after TACE with bevacizumab or placebo. Comparisons between groups were performed with t-tests and Chi-squared tests, where appropriate. Overall survival (OS) was defined as the time from start of bevacizumab or placebo until the date of death/last follow-up, respectively.

Results

The patient-related sensitivity of [¹¹C]-acetate PET, [¹⁸F]-FDG PET, and combined [¹¹C]-acetate and [¹⁸F]-FDG PET was 68%, 45%, and 73%, respectively. There was a significantly higher rate of conversion from [¹¹C]-acetate positive lesions to negative lesions in patients treated with TACE and bevacizumab as compared with that in patients with TACE and placebo (p < 0.05). In patients with negative acetate PET, the mean OS in patients treated with TACE and bevacizumab was 259 ± 118 days and was markedly shorter as compared with that (668 ± 217 days) in patients treated with TACE and placebo (p < 0.05). In patients treated with TACE and placebo, there was significant difference in mean OS in patients with positive FDG PET as compared with that in patients with negative FDG PET (p < 0.05). The HCC lesions had different tracer avidities showing the heterogeneity of HCC.

Conclusions

Our study suggests that combining [¹⁸F]-FDG with [¹¹C]-acetate PET could be useful for the management of HCC patients and might also provide relevant prognostic and molecular heterogeneity information.

Predictive Value of 18F-FDG PET/CT for Vascular Invasion in Patients With Hepatocellular Carcinoma Before Liver Transplantation

BACKGROUND

Positron emission tomography-computed tomography using F-fluorodeoxyglucose (F-FDG PET/CT) has been widely used in oncology. Vascular invasion of hepatocellular carcinoma (HCC) is associated with a high risk of tumor recurrence and low survival rates after liver transplantation (LT). This retrospective study determined the predictive value of F-FDG PET/CT for vascular invasion in patients with HCC before LT.

METHODS

Sixty-five patients with HCC who underwent F-FDG PET/CT before LT were retrospectively included between January 2010 and July 2012. Volumes of interest (VOIs) were drawn for the tumors and normal liver tissues, and the standardized uptake value (SUV) in each VOI was measured. The maximal SUV (SUVmax) of the tumor, the ratio of tumor SUVmax to normal liver SUVmax (TSUVmax/LSUVmax), and the ratio of tumor SUVmax to normal liver SUVmean (TSUVmax/LSUVmean) were measured. The predictive value of metabolic parameters and conventional prognostic factors were analyzed.

RESULTS

Vascular invasion was pathologically confirmed in 15 (23.08%) of 65 patients. Compared with patients without vascular invasion, patients with vascular invasion exhibited significantly higher serum alpha-fetoprotein (AFP) (P < 0.001), larger tumor size (P = 0.001), higher tumor number (P = 0.017), and higher SUVmax, TSUVmax/LSUVmax ratio, and higher TSUVmax/LSUVmean ratio (P = 0.008, P = 0.002, and P = 0.006, respectively). Univariate analysis revealed that SUVmax, TSUVmax/LSUVmax ratio, and TSUVmax/LSUVmean ratio of FDG PET/CT were significantly associated with vascular invasion in patients with HCC before LT (P = 0.019, P = 0.018, and P = 0.015, respectively). Multivariate analysis revealed that the TSUVmax/LSUVmean ratio of F-FDG PET/CT was a significant predictor of vascular invasion (P = 0.04) and that the TSUVmax/LSUVmax ratio of F-FDG PET/CT was an independent predictor of vascular invasion, although this finding demonstrated borderline statistical significance (P = 0.06) in patients with HCC before LT.

CONCLUSIONS

According to the study results, the TSUVmax/LSUVmean ratio is an independent and significant predictor of vascular invasion, and the TSUVmax/LSUVmax ratio of F-FDG PET/CT is an independent predictor of vascular invasion, which is the main negative outcome after LT. Therefore, FDG PET/CT can provide vital information for determining prognosis and selecting an optimal candidate of LT for HCC.

MR elastography of hepatocellular carcinoma: Correlation of tumor stiffness with histopathology features-Preliminary findings

PURPOSE

To determine if tumor stiffness by MR Elastography (MRE) is associated with hepatocellular carcinoma (HCC) pathologic features.

MATERIAL AND METHODS

A retrospective review was undertaken of all patients with pathologically confirmed HCC who underwent MRE prior to loco-regional therapy, surgical resection or transplant between 1/1/2007 to 12/31/2015. An independent observer measured tumor stiffness (kilopascals, kPa) by drawing regions of interest (ROI) covering the HCC and in the case of HCCs with non-enhancing/necrotic components, only the solid portion was included in the ROI. HCC tumor grade (WHO criteria), vascular invasion and tumor encapsulation were assessed from retrievable pathology specimens by an expert hepatobiliary pathologist. Tumor stiffness was compared by tumor grade, size, presence of capsule and vascular invasion using Student's t-test (or Exact Mann-Whitney test).

RESULTS

21 patients were identified who had pathologically confirmed HCCs and tumor MRE data. 17 patients (81.0%) had underlying chronic liver disease. The mean±SD tumor size (cm) was 5.3±3.9cm. The mean±SD tumor stiffness was 5.9±1.4kPa. Tumors were graded as well differentiated (N=2), moderately differentiated (N=11) and poorly differentiated (N=8). There was a trend toward increased tumor stiffness in well/moderately differentiated HCCs (6.5±1.2kPa; N=13) compared to poorly differentiated HCCs (4.9±1.2kPa; N=8) (p<0.01). There was no significant correlation between tumor stiffness and liver stiffness or tumor size. There was no significant difference in tumor stiffness by presence or etiology of chronic liver disease, vascular invasion or tumor encapsulation.

CONCLUSION

Preliminary data suggest that tumor stiffness by MRE may be able to differentiate HCC tumor grade.

Role of positron emission tomography/computed tomography in living donor liver transplantation for hepatocellular carcinoma

Living donor liver transplantation (LDLT) becomes an important option for treatment for patients with hepatocellular carcinoma (HCC). With the advance of imaging modalities such as computed tomography (CT) and magnetic resonance image (MRI), preoperative staging and diagnosis for HCC was improved in LDLT. However, morphological characteristics based on the tumor number and size do not represent the tumor pathology and prognosis clearly. Therefore, many criteria using various markers have been reported, but still have limitation to predict the pathology and prognosis. Recently, 18F-fluorodeoxyglucose-positron emission tomography/CT (18F-FDG PET/CT) was introduced to have the usefulness for detection of extrahepatic metastases and prediction of post-transplant prognosis in liver transplantation (LT). Furthermore, the hybrid concept with both biologic activity using PET/CT and morphologic tumor characteristics using CT and MRI was reported to be selection criteria for the patient with HCC waiting LDLT. We will discuss the role of 18F-FDG PET/CT in LDLT as various aspects including tumor detection, pathology prediction, prognosis prediction, and possibility of selecting criteria.