Positioning of 18F-fluorodeoxyglucose-positron emission tomography imaging in the management algorithm of hepatocellular carcinoma

Comparison of Al18F-NOTA-FAPI-74 and 18F-FDG PET/CT in the Evaluation and Staging of Hepatobiliary Malignancies: A Single-center Prospective Study

BACKGROUND

Accurate diagnosis and staging are crucial for the management of patients with hepatobiliary malignancies. Here, we investigated the efficacy of Al18F-NOTA-FAPI-74 PET/CT in detecting hepatobiliary malignancies and compared the results with 18F-FDG PET/CT.

PATIENTS AND METHODS

Participants with hepatobiliary malignancies were prospectively enrolled and underwent paired Al18F-NOTA-FAPI-74 and 18F-FDG PET/CT from April 2023 to March 2024. Histopathology and/or follow-up imaging served as the reference standard. The SUVmax of the primary and metastatic lesions between Al18F-NOTA-FAPI-74 and 18F-FDG PET/CT were compared using the Wilcoxon signed-rank test. The association between Al18F-NOTA-FAPI-74 uptake intensity and immunohistochemical FAP expression was analyzed with Spearman r correlation.

RESULTS

Our cohort comprised of 28 patients with hepatobiliary malignancies, including 12 with hepatocellular carcinoma, 13 with intrahepatic cholangiocarcinoma (ICC), 2 with perihilar cholangiocarcinoma, and 1 with gallbladder carcinoma. Of these 28 patients, 13 underwent PET/CT for initial staging and 15 for restaging. Al18F-NOTA-FAPI-74 PET/CT showed higher sensitivity than 18F-FDG PET/CT for detecting primary tumors [100% (13/13) vs 92.3% (12/13)], lymph node metastases [79.2% (42/53) vs 54.7% (29/53)], and bone and visceral metastases [97.6% (164/168) vs 69.0% (116/168)]. Al18F-NOTA-FAPI-74 PET/CT findings led to upstaging or restaging in 6 of 28 patients compared with the 18F-FDG PET/CT-based stage. In addition, Al18F-NOTA-FAPI-74 PET/CT detected tumor-related obstructive inflammation in 7 patients, while 18F-FDG PET/CT detected it in only 1 patient (25% vs 3.6%). All these 7 patients suffered from cholangiocarcinomas, including 5 with ICC and 2 with perihilar cholangiocarcinomas. The SUVmax of obstructive inflammation on Al18F-NOTA-FAPI-74 PET/CT was significantly lower than that of tumor (median SUVmax, 4.0 vs 8.8; P = 0.008). A positive correlation was found between FAPI uptake and FAP expression (r = 0.730, P = 0.04).

CONCLUSIONS

In patients with hepatobiliary malignancies, Al18F-NOTA-FAPI-74 PET/CT outperformed 18F-FDG PET/CT in detecting primary tumors and metastatic lesions, resulting in more accurate staging or restaging. In addition, Al18F-NOTA-FAPI-74 PET/CT showed good detection efficacy for tumor-related obstructive inflammation, which was only found in cholangiocarcinoma, thus rendering Al18F-NOTA-FAPI-74 the potential to differentiate ICC from hepatocellular carcinoma.

First-Line Durvalumab plus Tremelimumab Treatment for Unresectable Hepatocellular Carcinoma in Real-World Clinical Practice

INTRODUCTION

Durvalumab plus tremelimumab combination therapy (STRIDE regimen) is a new first-line option for unresectable hepatocellular carcinoma (uHCC), but little real-world data are available to determine which patients are most likely to respond.

METHODS

This study retrospectively evaluated patients with uHCC who were treated with the STRIDE regimen as the 1st line at our hospital. The primary endpoint of the study was the objective response rate (ORR). We focused on identifying factors associated with cases that had a favorable response.

RESULTS

Twenty-one patients were included. In best response, there were 11 partial response cases, with an ORR of 52.4%. Median progression-free survival was 6.8 months, and overall survival did not reach the median time. A high tumor-to-liver ratio of the maximum value of the standardized uptake value (TLR) on baseline fluorodeoxyglucose positron emission tomography (FDG-PET) was associated with response, while TLRs were significantly higher in poorly differentiated uHCC.

CONCLUSION

The STRIDE regimen may be beneficial for systemic therapy-naive uHCC patients. High TLR on baseline FDG-PET could be a potentially useful biomarker for response.

Hepatic Positron Emission Tomography: Applications in Metabolism, Haemodynamics and Cancer

Evaluating in vivo the metabolic rates of the human liver has been a challenge due to its unique perfusion system. Positron emission tomography (PET) represents the current gold standard for assessing non-invasively tissue metabolic rates in vivo. Here, we review the existing literature on the assessment of hepatic metabolism, haemodynamics and cancer with PET. The tracer mainly used in metabolic studies has been [¹⁸F]2-fluoro-2-deoxy-D-glucose (¹⁸F-FDG). Its application not only enables the evaluation of hepatic glucose uptake in a variety of metabolic conditions and interventions, but based on the kinetics of ¹⁸F-FDG, endogenous glucose production can also be assessed. 14(R,S)-[¹⁸F]fluoro-6-thia-Heptadecanoic acid (¹⁸F-FTHA), ¹¹C-Palmitate and ¹¹C-Acetate have also been applied for the assessment of hepatic fatty acid uptake rates (¹⁸F-FTHA and ¹¹C-Palmitate) and blood flow and oxidation (¹¹C-Acetate). Oxygen-15 labelled water (¹⁵O-H₂O) has been used for the quantification of hepatic perfusion. ¹⁸F-FDG is also the most common tracer used for hepatic cancer diagnostics, whereas ¹¹C-Acetate has also shown some promising applications in imaging liver malignancies. The modelling approaches used to analyse PET data and also the challenges in utilizing PET in the assessment of hepatic metabolism are presented.

State of the Art in Artificial Intelligence and Radiomics in Hepatocellular Carcinoma

The most common liver malignancy is hepatocellular carcinoma (HCC), which is also associated with high mortality. Often HCC develops in a chronic liver disease setting, and early diagnosis as well as accurate screening of high-risk patients is crucial for appropriate and effective management of these patients. While imaging characteristics of HCC are well-defined in the diagnostic phase, challenging cases still occur, and current prognostic and predictive models are limited in their accuracy. Radiomics and machine learning (ML) offer new tools to address these issues and may lead to scientific breakthroughs with the potential to impact clinical practice and improve patient outcomes. In this review, we will present an overview of these technologies in the setting of HCC imaging across different modalities and a range of applications. These include lesion segmentation, diagnosis, prognostic modeling and prediction of treatment response. Finally, limitations preventing clinical application of radiomics and ML at the present time are discussed, together with necessary future developments to bring the field forward and outside of a purely academic endeavor.

Prognostic value of imaging-based parameters in patients with intermediate-stage hepatocellular carcinoma undergoing transarterial radioembolization

OBJECTIVE

Patients with inoperable multilobar hepatocellular carcinoma (HCC) Barcelona Clinic Liver Cancer (BCLC) stage B, who have failed other liver-directed treatment options, are ideal candidates for transarterial radioembolization (TARE) with Yttrium-90 (Y-90)-labeled glass spheres. There is limited data regarding variables that impact the prognosis and outcome in these patients. 99mTc-MAA scan for lung shunt fraction (LSF) and 18F-FDG PET/CT are performed during initial workup. We, therefore, decided to assess the prognostic impact of LSF and metabolic parameters, such as maximum SUVmax, MTV and TLG in patients undergoing TARE for HCC.

METHODS

We retrospectively analyzed 64 patients of HCC, between January 2010 and December 2016, deemed suitable for TARE. Pre-TARE LSF was computed on 99mTc MAA scan, and SUVmax, MTV and TLG on fluoro-deoxyglucose positron emission tomography/computed tomography were measured using automated software by 3D region of interest. LSF and PET parameters were stratified using optimal cut-offs derived from receiver operating curve analysis. Survival curves for the groups were estimated using the Kaplan-Meier method and were compared using log-rank test.

RESULTS

Overall survival (OS) was 15 months. In univariate analysis, high LSF (greater than 7.19), MTV and TLG were statistically significant and were associated with poor OS. In multivariate analysis, TLG (P value 0.044), MTV (P value 0.290) and LSF (P value 0.010) were independent predictors of outcome, after adjustment for significant univariate variables. However, SUVmax was not statistically significant for OS.

CONCLUSIONS

LSF, MTV and TLG are significant independent prognostic indicators of outcome in patients undergoing TARE for HCC.

Comparison of PET imaging of activated fibroblasts and 18F-FDG for diagnosis of primary hepatic tumours: a prospective pilot study

PURPOSE

This study aimed to compare the performance of ⁶⁸Ga-labelled fibroblast activating protein inhibitor (FAPI) PET and ¹⁸F-FDG PET for imaging of hepatic tumours.

METHODS

We prospectively assessed 20 patients with suspected intrahepatic lesions. Tumour radiological features, pathology, or follow-up examinations were assessed as ground truth in correlation with PET scans. Semiquantitative analysis was additionally performed by measuring the standardised uptake value (SUV). Tumour-to-liver background ratios (TBR) were calculated and compared between ⁶⁸Ga-FAPI PET and ¹⁸F-FDG PET. FAPI expression was assessed by immunochemistry in samples obtained from 7 patients with hepatocellular carcinomas (HCC)/intrahepatic cholangiocarcinoma (ICC) or granulomas.

RESULTS

Primary intrahepatic tumours, including 16 HCC in 14 patients and 4 ICC in 3 patients with extrahepatic metastases, were determined by histology (n = 14) and clinical examinations (n = 3). Based on visual analysis, 17 patients presented elevated ⁶⁸Ga-FAPI uptake (sensitivity: 100%, specificity: 100%), while 7 patients presented ¹⁸F-FDG avid tumours (sensitivity: 58.8%, specificity: 100%). ⁶⁸Ga-FAPI PET/CT identified 17 extrahepatic metastases vs. 13 in ¹⁸F-FDG PET/CT in 2 ICC patients. Three benign liver nodules in three patients showed negligible uptake in dual-PET scans. The SUV_{max_HCC} = 8.47 ± 4.06 and TBR_{max_HCC} = 7.13 ± 5.52, and SUV_{max_ICC} = 14.14 ± 2.20 TBR_{max_ICC} = 26.46 ± 4.94 in ⁶⁸Ga-FAPI-04 PET/CT were significantly higher than the ¹⁸F-FDG uptake presenting SUV_{max_HCC} = 4.86 ± 3.58 and TBR_{max_HCC} = 2.39 ± 2.21, and SUV_{max_ICC} = 9.19 ± 3.60 and TBR_{max_ICC} = 2.39 ± 2.21 (all p values < 0.05). ICC patients showed higher levels of FAPI uptake in the primary hepatic lesions compared to extrahepatic metastases, TBR_{max_ICC} = 15.18 ± 5.80 (p = 0.04).

CONCLUSIONS

⁶⁸Ga-FAPI PET-CT has superior potential in the detection of primary hepatic malignancy compared to ¹⁸F-FDG.

Positron-emission tomography for hepatocellular carcinoma: Current status and future prospects

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer mortality worldwide. Various imaging modalities provide important information about HCC for its clinical management. Since positron-emission tomography (PET) or PET-computed tomography was introduced to the oncologic setting, it has played crucial roles in detecting, distinguishing, accurately staging, and evaluating local, residual, and recurrent HCC. PET imaging visualizes tissue metabolic information that is closely associated with treatment. Dynamic PET imaging and dual-tracer have emerged as complementary techniques that aid in various aspects of HCC diagnosis. The advent of new radiotracers and the development of immuno-PET and PET-magnetic resonance imaging have improved the ability to detect lesions and have made great progress in treatment surveillance. The current PET diagnostic capabilities for HCC and the supplementary techniques are reviewed herein.

Emerging role of 18F-fluorodeoxyglucose positron emission tomography for guiding management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of major causes of cancer mortality worldwide. For decades, ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been widely used for staging, predicting prognosis, and detecting cancer recurrence in various types of malignant diseases. Due to low sensitivity of FDG PET for detecting intrahepatic HCC lesions, the clinical value of FDG PET in HCC patients has been limited. However, recent studies with diverse analytic methods have shown that FDG PET has promising role in aiding management of HCC patients. In this review, we will discuss the clinical role of FDG PET for staging, predicting prognosis, and evaluating treatment response in HCC. Further, we will focus on recent clinical studies regarding implication of volumetric FDG PET parameters, the significance of FDG uptake in HCC for selecting treatment and predicting treatment response, and the use of radiomics of FDG PET in HCC.

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.

18F-FDG-PET for Assessing Biological Viability and Prognosis in Liver Transplant Patients with Hepatocellular Carcinoma

Liver transplantation (LT) has become standard of care in patients with non-resectable early stage hepatocellular carcinoma (HCC) in liver cirrhosis. Currently, patient selection for LT is strictly based on tumor size and number, provided by the Milan criteria. This may, however, exclude patients with advanced tumor load but favourable biology from a possibly curative treatment option. It became clear in recent years that biological tumor viability rather than tumor macromorphology determines posttransplant outcome. In particular, microvascular invasion and poor grading reflect tumor aggressiveness and promote the risk of tumor relapse. Pretransplant biopsy is not applicable due to tumor heterogeneity and risk of tumor cell seeding. ¹⁸F-fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET), an established nuclear imaging device in oncology, was demonstrated to non-invasively correlate with unfavorable histopathologic features. Currently, there is an increasing amount of evidence that ¹⁸F-FDG-PET is very useful for identifying eligible liver transplant patients with HCC beyond standard criteria but less aggressive tumor properties. In order to safely expand the HCC selection criteria and the pool of eligible liver recipients, tumor evaluation with ¹⁸F-FDG-PET should be implemented in pretransplant decision process.

Preoperative Fluorine 18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Prediction of Microvascular Invasion in Small Hepatocellular Carcinoma

OBJECTIVES

This study aimed to assess the value of preoperative fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET-CT) for predicting microvascular invasion (MVI) in small hepatocellular carcinoma (HCC).

METHODS

We retrospectively examined 60 patients who received F-FDG PET-CT prior to hepatic resection for small HCC (≤30 mm) with subsequent MVI confirmation by histopathology. The associations between PET-positive status and tumor factors were assessed. Furthermore, independent predictors for MVI and diagnostic utility of each MVI predictor were assessed.

RESULTS

Multivariate analysis revealed the presence of MVI as an independent predictor of PET-positive status (P = 0.023). Maximum standardized uptake value (SUVmax) of 3.2 or greater (P = 0.017) and lens culinaris agglutinin a-reactive α-fetoprotein (AFP-L3) 19% or greater (P = 0.010) were independent predictors of MVI. Areas under the receiver operating characteristic curves for SUVmax of 3.2 or greater, AFP-L3 19% or greater, and both factors combined for predicting MVI were 0.712 (0.493-0.932), 0.755 (0.563-0.947), and 0.856 (0.721-0.991), respectively. The sensitivity and specificity for predicting MVI were 77.8% and 74.5% for SUVmax of 3.2 or greater, 66.7% and 84.3% for AFP-L3 19% or greater, and 88.9% and 82.4% for the combination.

CONCLUSIONS

F-FDG PET-CT and AFP-L3 may be useful for predicting MVI in small HCC, and the combination of the 2 factors provided reliable assessment for selection of suitable hepatic resection and liver transplantation candidates.

Prediction of Posttransplantation Recurrence of Hepatocellular Carcinoma Using Metabolic and Volumetric Indices of 18F-FDG PET/CT

(18)F-FDG PET is an effective method of predicting recurrence of hepatocellular carcinoma (HCC) after liver transplantation. We compared recently introduced metabolic and volumetric (18)F-FDG PET/CT indices with the current clinicopathologic predictors for ability to predict recurrence.

METHODS

In total, 110 HCC patients who underwent (18)F-FDG PET and liver transplantation were enrolled. On PET, SUVs and tumor-to-background ratios (TBRs) were measured as metabolic activity indices. Various metabolic tumor volumes and uptake-volume products (UVP) were also measured as volumetric indices. The ability of these indices and other clinicopathologic factors to predict recurrence was compared.

RESULTS

All metabolic and volumetric indices were significant for recurrence prediction on receiver-operating-characteristic curve analyses (P < 0.001). On univariate survival analyses, all PET indices-as well as tumor size, tumor number, the Milan criteria, tumor grade, vascular invasion, and T-stage-were significant factors. However, on multivariate analyses, tumor size, tumor grade, maximum TBR, and UVP calculated by inferior vena cava activity were significant factors (P = 0.004, 0.014, 0.009, and 0.021, respectively). When the Milan criteria and PET factors were included in the multivariate analysis, the Milan criteria (P = 0.029), maximum TBR (P < 0.001), and UVP (P = 0.016) were significant.

CONCLUSION

Volumetric and metabolic activity indices of (18)F-FDG PET are effective predictors of posttransplantation HCC recurrence. In addition to clinicopathologic factors, these indices need to be considered in the selection of candidates for liver transplantation.

Prognostic significance of parameters from pretreatment (18)F-FDG PET in hepatocellular carcinoma: a meta-analysis

PURPOSE

The prognostic value of (18)F-deoxyglucose positron emission tomography ((18)F-FDG PET) on hepatocellular carcinoma (HCC) remains inconclusive. This study aims to investigate the prognostic role of pretreatment (18)F-FDG PET on HCC patients by meta-analysis.

METHODS

PubMed, Embase, Cochrane library, and Wanfang databases were searched until June 2015. Hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) were synthesized by Stata 10.0, and the combined results were used as effective values.

RESULTS

Twenty-two studies containing a total of 1721 patients were identified. According to random-effect model, meta-analysis results showed that high Tumor SUV/Liver SUV (Tsuv/Lsuv) ratio was significantly associated with poorer overall survival (OS) (HR = 2.04; 95% CI 1.50-2.79; P = 0.000) and poorer disease-free survival (HR = 7.17; 95% CI 3.58-14.36; P = 0.000); and high Tumor SUV (Tsuv) value was also correlated with poor OS (HR = 1.53; 95% CI 1.26-1.87; P = 0.000). Meanwhile, subgroup analysis results showed that the significant association above was not altered by study sample size, parameter cutoff value, analytic method, and follow-up period, but there was no significant association between Tsuv/Lsuv ratio and OS in patients who underwent resection (HR = 1.71; 95% CI 1.00-2.92; P = 0.052).

CONCLUSIONS

Both high Tsuv/Lsuv ratio and high Tsuv value are associated with poor prognosis in HCC patients. Therefore, pretreatment (18)F-FDG PET is a useful tool in predicting the prognosis of HCC patients. More studies with explicit treatment modalities are required to investigate the prognostic value of pretreatment (18)F-FDG PET on HCC patients.

Current surgical treatment strategies for hepatocellular carcinoma in North America

Hepatocellular carcinoma (HCC) is an aggressive tumor that often occurs in the setting of chronic liver disease. Many patients do not initially manifest any symptoms of HCC and present late when cure with surgical resection or transplantation is no longer possible. For this reason, patients at high risk for developing HCC are subjected to frequent screening processes. The surgical management of HCC is complex and requires an inter-disciplinary approach. Hepatic resection is the treatment of choice for HCC in patients without cirrhosis and is indicated in some patients with early cirrhosis (Child-Pugh A). Liver transplantation has emerged in the past decade as the standard of care for patients with cirrhosis and HCC meeting Milan criteria and in select patients with HCC beyond Milan criteria. Loco-regional therapy with transarterial chemoembolization, transarterial embolization, radiofrequency ablation and other similar local treatments can be used as neo-adjuvant therapy to downstage HCC to within Milan criteria or as a bridge to transplantation in patients on transplant wait list.