Usefulness of positron emission tomography with fluorine-18-fluorodeoxyglucose for predicting outcome in patients with hepatocellular carcinoma

Update on PET Radiopharmaceuticals for Imaging Hepatocellular Carcinoma

Numerous positron emission tomography (PET) targets for detection and staging of hepatocellular cancer have been developed in recent years. Hepatocellular carcinomas (HCCs) are clinically and pathologically heterogeneous tumours with a high tendency to be aggressive and unresponsive to chemotherapy. Early detection is essential, and the need for an adequate imaging biomarker, which can overcome some of the limitations of conventional radiological imaging, is persistent. Flourine-18 (18F) flourodeoxyglucose (FDG), the most widely used PET radiopharmaceutical, has proven disappointing as a possible staple in the evaluation of HCC. This disappointment had led to experimentation with carious radiotracers, such as the choline derivatives, acetate, and prostate-specific membrane antigen, which appear to complement and/or enhance the role of FDG. In this study, we look at the various PET radiopharmaceuticals that have been used for imaging HCC and the particular pathways that they target in HCC and liver cancers.

18F-Fluorodeoxyglucose-PET-Computerized Tomography and non-Fluorodeoxyglucose PET-Computerized Tomography in Hepatobiliary and Pancreatic Malignancies

Molecular imaging with PET-computerized tomography (PET-CT) plays an important role in oncology. There is current and evolving evidence supporting the use of fluorodeoxyglucose (FDG) and non-FDG tracers in assessment patients with hepatobiliary and pancreatic cancers in various clinical scenarios. In this chapter, we discuss the advantages and limitations of FDG and non-FDG PET-CT in the management of patients with hepatobiliary and pancreatic cancers.

PET-Based Radiogenomics Supports mTOR Pathway Targeting for Hepatocellular Carcinoma

PURPOSE

This work aimed to explore in depth the genomic and molecular underpinnings of hepatocellular carcinoma (HCC) with increased 2[18F]fluoro-2-deoxy-d-glucose (FDG) uptake in PET and to identify therapeutic targets based on this imaging-genomic surrogate.

EXPERIMENTAL DESIGN

We used RNA sequencing and whole-exome sequencing data obtained from 117 patients with HCC who underwent hepatic resection with preoperative FDG-PET/CT imaging as a discovery cohort. The primary radiogenomic results were validated with transcriptomes from a second cohort of 81 patients with more advanced tumors. All patients were allocated to an FDG-avid or FDG-non-avid group according to the PET findings. We also screened potential drug candidates targeting FDG-avid HCCs in vitro and in vivo.

RESULTS

High FDG avidity conferred worse recurrence-free survival after HCC resection. Whole transcriptome analysis revealed upregulation of mTOR pathway signals in the FDG-avid tumors, together with higher abundance of associated mutations. These clinical and genomic findings were replicated in the validation set. A molecular signature of FDG-avid HCCs identified in the discovery set consistently predicted poor prognoses in the public-access datasets of two cohorts. Treatment with an mTOR inhibitor resulted in decreased FDG uptake followed by effective tumor control in both the hyperglycolytic HCC cell lines and xenograft mouse models.

CONCLUSIONS

Our PET-based radiogenomic analysis indicates that mTOR pathway genes are markedly activated and altered in HCCs with high FDG retention. This nuclear imaging biomarker may stimulate umbrella trials and tailored treatments in precision care of patients with HCC.

Metabolic Phenotypes, Dependencies, and Adaptation in Lung Cancer

Lung cancer is a heterogeneous disease that is subdivided into histopathological subtypes with distinct behaviors. Each subtype is characterized by distinct features and molecular alterations that influence tumor metabolism. Alterations in tumor metabolism can be exploited by imaging modalities that use metabolite tracers for the detection and characterization of tumors. Microenvironmental factors, including nutrient and oxygen availability and the presence of stromal cells, are a critical influence on tumor metabolism. Recent technological advances facilitate the direct evaluation of metabolic alterations in patient tumors in this complex microenvironment. In addition, molecular alterations directly influence tumor cell metabolism and metabolic dependencies that influence response to therapy. Current therapeutic approaches to target tumor metabolism are currently being developed and translated into the clinic for patient therapy.

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.

Radiolabelled PSMA PET/CT or PET/MRI in hepatocellular carcinoma (HCC): a systematic review

Introduction

Radiolabelled prostate-specific membrane antigen PSMA-based PET/CT or PET/MRI is a whole-body imaging technique usually performed for the detection of prostate cancer lesions. PSMA has been also demonstrated to be expressed by the neovasculature of many other solid tumors. The aim of this review is to evaluate the possible diagnostic role of radiolabelled PSMA PET/CT or PET/MRI in patients with hepatocellular carcinoma, by summarizing the available literature data.

Methods

A wide literature search of the PubMed/MEDLINE, Scopus, Embase and Cochrane library databases was made to find relevant published articles about the diagnostic performance of radiolabelled PSMA binding agents in PET/CT or PET/MRI imaging of patients with hepatocellular carcinoma.

Results

Ten case reports and three studies showed that hepatocellular carcinoma is PSMA-avid.

Conclusion

Radiolabelled PSMA imaging seems to be useful in analyzing hepatocellular carcinoma. Further studies enrolling a wider population are needed to clarify the real clinical and diagnostic role of radiolabelled PSMA in this setting.

18F-fluorodeoxyglucose PET/CT as an independent predictor for patients with hepatocellular carcinoma combined with major portal vein tumor thrombus

PURPOSE

Hepatocellular carcinoma (HCC) patients with major portal vein tumor thrombosis (mPVTT) complications were generally characterized by extremely poor prognoses. The aim of this study was to explore the role of 18F-fluorodeoxyglucose (18F-FDG) PET/CT imaging in predicting HCC complicated by mPVTT.

METHODS

Five hundred one HCC patients received surgery in our hospital during November 2008 to December 2014, among which 32 patients (6.4%) were diagnosed as HCC complicated by mPVTT. Six cases were excluded for reasons of complex medical conditions, including 2 cases of salvage liver transplantation, 2 cases of re-resection, 1 case of mPVTT combined with inferior vina cava tumor thrombosis, and 1 case of residual portal vein tumor thrombosis. Ultimately, 26 cases were enrolled in this study. The maximal tumor standardized uptake value (SUVmax) was identified as a predictive factor and detected. The univariate and multivariate regression analyses were performed to identify the prognostic factors for recurrence-free survival (RFS) and overall survival (OS) of HCC patients complicated by mPVTT.

RESULTS

Our results showed that the median OS was 16 months. The 1-, 3-, and 5-year cumulative OS was 55.6%, 31.7%, and 31.7%, respectively. The multivariate regression analysis revealed that SUVmax ≥ 4.65 was the only independent risk factor for RFS and OS.

CONCLUSION

SUVmax was an independent predictor for RFS and OS of patients suffering from both HCC and mPVTT. L ow SUVmax could serve as an effective factor for selecting candidates with low recurrence risks and for helping with improving patient survival after surgical resection.

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.

Change in standardized uptake values in delayed 18F-FDG positron emission tomography images in hepatocellular carcinoma

Delayed 18F-2-fluoro-2-deoxy-D-glucose (F-FDG) positron emission tomography (PET) imaging has been associated with improved diagnostic yield in several malignancies; however, data on the use of delayed imaging in patients with hepatocellular carcinoma (HCC) is scarce. This study aimed to examine tumoral and background standardized uptake value (SUV) alterations in dual-phase F-FDG PET/computed tomography (CT) imaging.Fifty-two HCC cases underwent dual-time-point F-FDG PET/CT examination where early and delayed images were obtained. The maximum and mean SUVs (SUVmax and SUVmean) of the tumor were determined for both time points. Similarly, the average SUVmean were also determined for background (liver, soft tissue, and spleen). Changes in tumoral and background SUV between early and delayed images were examined.The mean age was 62.0 ± 12.9 years (range, 20-88 years) and the majority of the patients were men (86.5%). Tumor SUVs, both tumor SUVmean and tumor SUVmax, significantly increased at delayed images when compared to early images. In contrast, the average SUVmean for the liver, soft tissue, and spleen significantly decreased at delayed images.A significant increase in tumor SUV in delayed images in contrast to a significant decrease in background SUVs suggests that delayed images in HCC may contribute to diagnostic performance through a potential increase in the contrast between the tumor and background. However, further studies with larger sample sizes including patients with benign lesions and different grades of the disease are warranted to better elucidate the diagnostic contribution as well as the association of delayed imaging values with prognosis.

11C-acetate and 18F-fluorodeoxyglucose positron emission tomography/computed tomography dual imaging for the prediction of response and prognosis after transarterial chemoembolization

The aim of the present study was to evaluate the clinical significance of dual radiotracer studies, C-acetate and F-fluoro-D-glucose positron emission tomography/computed tomography (F-FDG PET/CT), for the prediction of response and recurrence after transarterial chemoembolization (TACE).This study retrospectively included a total 42 hepatoceullar carcinoma (HCC) patients (median age, 59; range, 34-85 years old) who underwent C-acetate and F-FDG PET/CT concurrently. Tumor uptake normalized by liver uptake (TNR; maximum tumor SUV to mean normal liver SUV ratio) was obtained first. Then, FAratio, which is the ratio of F-FDG TNR (TNR_FDG) to C-acetate TNR, was obtained and correlated with response after TACE and recurrence-free survival (RFS), using a Cox multivariate proportional-hazard model.Among clinical factors, including the Hepatoma Arterial Embolization Prognostic score and positron emission tomography (PET) parameters, multiple regression analysis revealed FAratio and tumor size to be the only significant factors. As a PET parameter, FAratio exhibited the largest area under the curve in the prediction of response after TACE. In the Cox multivariate proportional-hazard model, TNR_FDG was the only significant predictive factor for RFS. In subgroup analysis, TNR_FDG was the only significant predictive factor for recurrence in intermediate stage patients. However, FAratio was the only significant predictive factor for recurrence in advanced stage patients.Dual radiotracer use of C-acetate and F-FDG PET/CT contributed to the prediction of response and recurrence after TACE. Used in addition to F-FDG, C-acetate PET/CT could give additional information in advanced stage patients. Based on the characteristics of tumor metabolism assessed by dual radiotracer PET/CT, treatment plans could be more personalized and optimized.

Prognosis of preoperative positron emission tomography uptake in hepatectomy patients

Purpose

Preoperative F-18-fluoro-2-deoxy-glucose positron emission tomography (18F-FDG PET) imaging results appear to predict tumor recurrence and patient survival. The present study compared outcomes between PET-positive and PET-negative groups with HBV-related hepatocellular carcinoma (HCC) who underwent curative hepatectomy and assessed the prognostic value of positive PET-CT for HCC recurrence and death.

Methods

This study included patients who underwent liver resection of solitary HCC between 2007 and 2014 based on preoperative radiological images. There were 133 patients in the PET-positive group and 93 in the PET-negative group.

Results

There were no statistically significant differences in baseline, perioperative, or pathologic characteristics between the 2 groups except HBsAg titer, tumor size, and presence of bile duct tumor thrombi. Multivariate analysis showed that tumor size >3.5 cm and HBsAg titer >1,000 cutoff index were predisposing factors of positive PET-CT. Disease-free survival and overall survival rate at 1, 3, and 5 years were 76.3%, 64.4%, 60.3% and 96.8%, 91.1%, 85.1% in the PET-negative group, respectively, compared with 70.7%, 62.2%, 58.9% and 98.5%, 97.0%, 97.0% in the PET-positive group (P = 0.547 and P = 0.046). Multivariate analysis showed that positive PET-CT was closely associated with increased patient survival, but was not related to HCC recurrence.

Conclusion

These results suggest that positive PET findings are not a predisposing factor for recurrence of HBV-related HCC patients, but appear to be associated with improved patient survival. Further prospective studies are needed to confirm the prognostic value of 18F-FDG PET in these patients.

Imaging Cancer Metabolism

It is widely accepted that altered metabolism contributes to cancer growth and has been described as a hallmark of cancer. Our view and understanding of cancer metabolism has expanded at a rapid pace, however, there remains a need to study metabolic dependencies of human cancer in vivo. Recent studies have sought to utilize multi-modality imaging (MMI) techniques in order to build a more detailed and comprehensive understanding of cancer metabolism. MMI combines several in vivo techniques that can provide complementary information related to cancer metabolism. We describe several non-invasive imaging techniques that provide both anatomical and functional information related to tumor metabolism. These imaging modalities include: positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS) that uses hyperpolarized probes and optical imaging utilizing bioluminescence and quantification of light emitted. We describe how these imaging modalities can be combined with mass spectrometry and quantitative immunochemistry to obtain more complete picture of cancer metabolism. In vivo studies of tumor metabolism are emerging in the field and represent an important component to our understanding of how metabolism shapes and defines cancer initiation, progression and response to treatment. In this review we describe in vivo based studies of cancer metabolism that have taken advantage of MMI in both pre-clinical and clinical studies. MMI promises to advance our understanding of cancer metabolism in both basic research and clinical settings with the ultimate goal of improving detection, diagnosis and treatment of cancer patients.

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.

Significance of preoperative fluorodeoxyglucose-positron emission tomography in prediction of tumor recurrence after liver transplantation for hepatocellular carcinoma patients: a Japanese multicenter study

BACKGROUND

In the present study, we conducted a multicenter nationwide survey to investigate the effects of preoperative fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) on the prediction of hepatocellular carcinoma (HCC) recurrence after liver transplantation (LT).

METHODS

From 16 Japanese LT centers, data were collected on 182 recipients with HCC who underwent living donor liver transplantation (LDLT) between February 2005 and November 2013. PET-positive status was defined as increased uptake of FDG in the tumor compared to the surrounding non-tumor liver tissue. The median follow-up after LDLT was 54.5 months (range 1-125 months).

RESULTS

Postoperative HCC recurrence occurred in 23 patients. Multivariate analysis revealed that exceeding the Milan criteria (MC), alpha-fetoprotein (AFP) level ≥115 ng/ml, and PET-positive status were significant and independent risk factors for recurrence. In the over-MC group, a subgroup of patients with AFP level <115 ng/ml and PET-negative status (n = 22) had a significantly lower 5-year recurrence rate than the other patients (n = 27, 19% vs. 53%, P = 0.019).

CONCLUSIONS

These results suggest that preoperative FDG-PET status offers additional information on HCC recurrence risk after LT. Over-MC patients with PET-negative status and lower AFP level may achieve successful outcome comparable to that of within-MC patients.

18F-FDG PET/CT Can Predict Survival of Advanced Hepatocellular Carcinoma Patients: A Multicenter Retrospective Cohort Study

Barcelona Clinic Liver Cancer (BCLC) stage C hepatocellular carcinoma (HCC) consists of a heterogeneous group of patients with a wide range of survival times, requiring further prognostic stratification to facilitate treatment allocation. We evaluated the prognostic value of ¹⁸F-FDG uptake on PET/CT at the time of presentation in patients with BCLC stage C HCC. Methods: A total of 291 patients with BCLC stage C HCC who underwent ¹⁸F-FDG PET/CT between 2009 and 2010 for staging were retrospectively enrolled from 7 university hospitals. The patients were further divided into 2 groups according to the extent of disease, as intrahepatic or extrahepatic. Tumor-to-liver SUV ratio (TLR) of the primary tumor was measured on ¹⁸F-FDG PET/CT. Prognostic values of TLR and other clinical variables were analyzed to predict overall survival (OS) in univariate and multivariate analyses. Differences in the OS stratified by TLR were examined by the Kaplan-Meier method. Results: Higher TLR was associated with extrahepatic disease (P = 0.018). On multivariate analysis, Child-Pugh classification and TLR were independent prognostic factors in the intrahepatic disease group (all P < 0.05), whereas TLR was the only independent prognostic factor in the extrahepatic disease group (P < 0.05). Patients with high TLR showed a significantly worse OS than those with low TLR (P < 0.05) in both groups. Conclusion: In patients with BCLC stage C HCC, ¹⁸F-FDG uptake in the primary tumor was significantly higher in patients with extrahepatic disease than in those with intrahepatic disease. In addition, ¹⁸F-FDG uptake on pretreatment PET/CT had an incremental prognostic value for OS in both intrahepatic and extrahepatic disease groups.

Metabolic Activity by 18F-FDG-PET/CT Is Prognostic for Stage I and II Pancreatic Cancer

PURPOSE

Metabolic activity, as defined by F-FDG uptake on PET, is a prognostic marker for multiple malignancies; however, no study has examined the prognostic value of imaging with FDG PET in stage I and II pancreatic cancer. We examined the value of PET FDG uptake in early-stage pancreatic cancer patients.

METHODS

We identified patients with early-stage pancreatic cancer (I-II) who had FDG PET scan performed as part of their preoperative evaluation. The patients were divided into either high or low FDG uptake according to the median primary tumor standard uptake value (SUVmax). Our primary end points were overall survival (OS) and recurrence-free survival (RFS). Kaplan-Meier estimate was used for survival analysis. Pathologic data were compared using the Fisher exact and χ tests.

RESULTS

One hundred five patients were identified: 51 patients with low FDG uptake and 54 patients with high FDG uptake. Eighty-five patients (81%) had PET avid tumors, whereas 20 (19%) patients did not. High FDG uptake correlated with pathologic stage (P = 0.012). Patients with low FDG uptake had significantly better median OS than patients with high FDG uptake (28 vs. 16 months; P = 0.036). Patients with low-FDG uptake had significantly longer median RFS than patients with high FDG uptake (14 vs. 12 months; P = 0.049).

CONCLUSIONS

Low FDG uptake in PET scans in patients with stage I and II pancreatic cancer correlates with improved OS and RFS. This supports the concept that glucose metabolic pathways are important in pancreatic cancer biology and that PET scan activity can be used as a prognostic biomarker after pancreatectomy.

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.

[Combined PET-MRI of the abdomen]

The first fully integrated combined positron emission tomography-magnetic resonance imaging (PET-MRI) scanners have been clinically available since 2010. Large prospective studies regarding indications and diagnostic accuracy of this new modality are not yet available; however, preliminary studies have shown a higher diagnostic accuracy and confidence compared to PET-computed tomography (PET-CT) in regions where MRI is known to be superior to CT, such as the liver. The benefit of MRI in accurate lesion characterization and the additional value of diffusion-weighted imaging (DWI) as a complementary functional modality by means of the apparent diffusion coefficient (ADC) is apparent in entities with low tracer uptake (e.g. due to small size) and a decreased or absent accumulation pattern on PET.

Prognostic value of pretreatment (18)F-FDG PET-CT in radiotherapy for patients with hepatocellular carcinoma

Purpose

The purpose of this study was to investigate the predictable value of pretreatment ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) in radiotherapy (RT) for patients with hepatocellular carcinoma (HCC) or portal vein tumor thrombosis (PVTT).

Materials and Methods

We conducted a retrospective analysis of 36 stage I-IV HCC patients treated with RT. ¹⁸F-FDG PET-CT was performed before RT. Treatment target was determined HCC or PVTT lesions by treatment aim. They were irradiated at a median prescription dose of 50 Gy. The response was evaluated within 3 months after completion of RT using the Response Evaluation Criteria in Solid Tumors (RECIST). Response rate, overall survival (OS), and the pattern of failure (POF) were analyzed.

Results

The response rate was 61.1%. The statistically significant prognostic factor affecting response in RT field was maximal standardized uptake value (maxSUV) only. The high SUV group (maxSUV ≥ 5.1) showed the better radiologic response than the low SUV group (maxSUV < 5.1). The median OS were 996.0 days in definitive group and 144.0 days in palliative group. Factors affecting OS were the %reduction of alpha-fetoprotein (AFP) level in the definitive group and Child-Pugh class in the palliative group. To predict the POF, maxSUV based on the cutoff value of 5.1 was the only significant factor in distant metastasis group.

Conclusion

The results of this study suggest that the maxSUV of ¹⁸F-FDG PET-CT may be a prognostic factor for treatment outcome and the POF after RT. A %reduction of AFP level and Child-Pugh class could be used to predict OS in HCC.

Predictive biomarkers of sorafenib efficacy in advanced hepatocellular carcinoma: Are we getting there?

Sorafenib is the current standard treatment for advanced hepatocellular carcinoma (HCC), but its efficacy is modest with low response rates and short response duration. Predictive biomarkers for sorafenib efficacy are necessary. However, efforts to determine biomarkers for sorafenib have led only to potential candidates rather than clinically useful predictors. Studies based on patient cohorts identified the potential of blood levels of angiopoietin-2, hepatocyte growth factor, insulin-like growth factor-1, and transforming growth factor-β1 for predicting sorafenib efficacy. Alpha-fetoprotein response, dynamic contrast-enhanced magnetic resonance imaging, and treatment-related side effects may serve as early surrogate markers. Novel approaches based on super-responders or experimental mouse models may provide new directions in biomarker research. These studies identified tumor amplification of FGF3/FGF4 or VEGFA and tumor expression of phospho-Mapk14 and phospho-Atf2 as possible predictive markers that await validation. A group effort that considers various prognostic factors and proper collection of tumor tissues before treatment is imperative for the success of future biomarker research in advanced HCC.

[18F]fludeoxyglucose positron emission tomography and computed tomography as a prognostic tool before liver transplantation, resection, and loco-ablative therapies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third most common cause of cancer-related death worldwide. Orthotopic liver transplantation (OLT) and resection are curative treatment options for well-selected patients with HCC, whereas loco-ablative therapy has been shown to prolong survival. Organ and treatment allocations for these patients are currently based on the number and size of tumors, as defined by the Milan criteria, and on functional capacity, and they are incorporated into the Barcelona Clinic Liver Cancer staging system and treatment strategy. Even though these staging criteria have markedly improved the outcomes of patients with HCC, they still lack accuracy in predicting the risk of tumor recurrence because they do not incorporate markers of tumor biology and behavior. Positron emission tomography (PET) and computed tomography (CT) with [(18) F]fludeoxyglucose ([(18) F]FDG) constitute an imaging modality for detecting tumor tissue that is metabolically active. Uptake of [(18) F]FDG is highly associated with tumor aggressiveness. In this review, we present the accumulating data on the use of [(18) F]FDG PET-CT as an in vivo biomarker and its predictive value in identifying patients at risk for HCC recurrence after liver transplantation, resection, or ablation. These data suggest that the introduction of [(18) F]FDG PET-CT into the imaging algorithm of patients planned for liver transplantation, resection, or ablation may improve outcomes.

The predictive value of metabolic tumor volume on FDG PET/CT for transarterial chemoembolization and transarterial chemotherapy infusion in hepatocellular carcinoma patients without extrahepatic metastasis

OBJECTIVE

The aim of this study was to evaluate the prognostic value of metabolic tumor volume (MTV) on pre-treatment F-18 fluorodeoxyglucose (FDG) PET/CT in patients with hepatocellular carcinoma (HCC).

METHODS

A total of 59 HCC patients who underwent FDG PET/CT before transarterial chemoembolization (TACE) or transarterial chemotherapy infusion (TACI) were retrospectively enrolled. The region of interest was drawn in the HCC and normal liver tissue. MTV2SD, defined as the sum of the voxels with higher standardized uptake values (SUV) than the SUV of the 97.5th percentile of voxels of the normal liver for each patient, was calculated using an intensity-volume histogram (IVH). The ratio of the maximum SUV of the tumor to the mean SUV of normal liver (T max/L mean) was also calculated. The prognostic significance of MTV2SD and Tmax/Lmean for progression-free survival (PFS) and overall survival (OS) was evaluated along with other clinical factors.

RESULTS

The tumor number, Tmax/Lmean, and MTV2SD were significant prognostic factors affecting PFS (p < 0.05), whereas tumor number, serum alpha-fetoprotein level, tumor stage, portal vein thrombosis, Tmax/Lmean, and MTV2SD were significant prognostic factors for OS (p < 0.05). In multivariate analysis, the tumor number and MTV2SD were independent prognostic factors for PFS (p < 0.05), whereas the independent prognostic factors for OS were tumor number, tumor stage, and MTV2SD (p < 0.05). The mean PFS and OS in patients with low MTV2SD (15.4 and 63.1 months, respectively) were significantly longer than those in patients with high MTV2SD (6.0 and 15.2 months, respectively; p = 0.005 and p < 0.0001, respectively).

CONCLUSIONS

Metabolic tumor volume was an independent prognostic factor for PFS and OS in patients with HCC. Therefore, FDG PET/CT can provide valuable prognostic information for HCC patients who undergo TACE or TACI.

Survival in patients with hepatocellular carcinoma treated with 90Y-microsphere radioembolization. Prediction by 18F-FDG PET

AIM

This retrospective study aims to evaluate the predictive value of FDG PET/CT in patients with unresectable hepatocellular carcinoma (HCC) undergoing radioembolization with yttrium-90 labeled microspheres (RE).

PATIENTS, METHODS

The study cohort comprised 33 patients who were treated with RE at our institution and underwent FDG PET/CT at baseline and four weeks after radioembolization. According to the baseline FDG metabolic status of the HCC lesions, patients were divided into two groups: FDG-negative (n = 12) and FDG-positive (n = 21) HCC. FDG-positive patients were further divided into early metabolic responders and non-responders according to the relative change in SUVmax of the treated lesions. Survival analyses were performed with the Kaplan-Meier method (log-rank test, p < 0.05). Multivariate analysis was performed to assess the influence of prognostic factors on overall survival (OS).

RESULTS

FDG-negative patients had a significantly longer OS (13 months, 95%CI 7-19) than FDG-positive patients (9 months, 95%CI 7-11; p = 0.010). Among FDG-positive patients, metabolic responders survived significantly longer than metabolic non-responders (10 months, 95%CI 8-12 vs. 5 months, 95%CI 4-6; p = 0.003). From the other baseline factors (including performance status, hepatic tumour burden, presence of extra-hepatic disease, administered activity) only the BCLC stage had a significant impact on OS (p = 0.028).

CONCLUSION

Pre- and post-therapeutic FDG PET independently predicts overall survival in patients with HCC undergoing radioembolization. Interestingly, early metabolic response seems to be assessable as early as four weeks post-treatment.

Diagnostic role of radiolabelled choline PET or PET/CT in hepatocellular carcinoma: a systematic review and meta-analysis

The role of fluorine-18-fluorodeoxygluose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in hepatocellular carcinoma (HCC) has not been firmly established yet and its sensitivity has been reported to be in the range of 40-60 %. Because of this relatively low sensitivity alternative tracers have been proposed. The aim of our review is to analyse the literature data on the diagnostic role of (18)F/(11)C-choline PET/CT in the evaluation of HCC. A comprehensive computer literature search of PubMed/MEDLINE, Embase and Scopus databases was conducted to find relevant published articles about the role of whole-body (18)F-choline or (11)C-choline PET or PET/CT in patients with HCC. Furthermore, a meta-analysis about the detection rate of this method in HCC was performed. Six articles were included in this systematic review and discussed. The meta-analysis of five out of six articles showed a DR of 84 % (95 % CI 79-89 %). The DR increased when poorly differentiated HCC was excluded from the analysis. Radiolabelled choline PET or PET/CT could be a valuable tool in detecting HCC and it is better than (18)F-FDG PET/CT, especially in well to moderately differentiated lesions; on the other hand, poorly differentiated and higher-stage HCC could be better evaluated with (18)F-FDG and dual tracer imaging should be considered and could be potentially useful to increase accuracy.

Does 18F-FDG positron emission tomography-computed tomography have a role in initial staging of hepatocellular carcinoma?

Background and Aim

The utility of fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET/CT) in initial staging of hepatocellular carcinoma (HCC) has yet to be fully explored. We assessed the usefulness of ¹⁸F-FDG PET/CT in initial staging of HCC.

Methods

A total of 457 consecutive patients initially diagnosed with HCC at Seoul National University Hospital between 2006 and 2012 were evaluated retrospectively to assess the impact of ¹⁸F-FDG PET/CT on staging and compliancy with Milan criteria, relative to dynamic CT of liver and chest x-ray.

Results

Seven among the 457 patients studied showed a shift in Barcelona Clinic Liver Cancer [BCLC] stage (A→C: 6 patients; B→C: 1 patient) and 5 patients who had originally met Milan criteria no longer qualified. ¹⁸F-FDG PET/CT had value in initial staging of early (stage A) or intermediate (stage B) HCC, as determined by dynamic CT of liver and BCLC or AJCC classifications, whereas BCLC stage 0 and stage C tumors were unchanged (P<0.001). ¹⁸F-FDG PET/CT disclosed additional metastases in patients with American Joint Committee on Cancer [AJCC] T2 (2.7%), T3a (5.3%), and T3b (4.8%) classifications.

Conclusions

In initial staging of HCC, ¹⁸F-FDG PET/CT provided additional information, impacting the patients with BCLC (stages A and B) and AJCC (T2 and T3) classifications. Its use might be thus appropriate for these patient subsets, especially if hepatic resection or liver transplantation is planned.

Potential role of FDG PET/CT in evaluating patients with hepatic incidentalomas

This review article is focused on the role of FDG PET/CT in diagnosing and characterizing hepatic incidentalomas. A large variety of unsuspected lesions can be detected in the liver both with ultrasound and CT performed for other reasons; the prevalence of liver incidentalomas increases in patients with chronic liver disease or preexisting oncologic history. The major challenge is to discriminate benign from malignant lesions. There is a large body of literature indicating that FDG PET/CT is a useful tool to this purpose even if it is unspecific (ie, it cannot differentiate a primary tumor from a secondary lesion). Occasionally, FDG PET/CT can be useful for biopsy guidance.

Implication of lymph node metastasis detected on 18F-FDG PET/CT for surgical planning in patients with peripheral intrahepatic cholangiocarcinoma

OBJECTIVES

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy after hepatocellular carcinoma. ICC can be divided into 2 types according to their location: peripheral and hilar types. Intense F-FDG uptake on PET was reported in peripheral ICC. However, the usefulness of PET/CT in detecting tumors and predicting prognosis in peripheral ICC has not been fully evaluated. In this study, we evaluated the clinical role of F-FDG PET/CT to predict the recurrence after the curative resection in patients with surgically indicated peripheral ICC.

METHODS

Eighteen patients with ICC underwent preoperative CT and F-FDG PET/CT scans. SUVmax of tumor, tumor to normal liver SUV ratio (TNR), lymph node status evaluated by F-FDG PET/CT, tumor and lymph node size measured by CT, vascular invasion confirmed by pathology, and satellite nodules found on CT were compared between 1-year recurrence group and recurrence-free group by chi-square test.

RESULTS

Of total 23 measurable lymph nodes, 4 nodes were positive and other 19 nodes were negative or equivocal on CT. Among those 23 nodes, 9 nodes were positive and other 14 nodes were negative on F-FDG PET/CT. The sensitivity and specificity of CT were 20.0% and 86.4%, and those of F-FDG PET/CT were 80.0% and 92.3%. In the comparison between 1-year recurrent and nonrecurrent groups, lymph node metastasis detected on F-FDG PET/CT had statistically positive correlation with the 1-year recurrence after surgical resection (P = 0.02). Other factors showed no statistically significant difference between the groups.

CONCLUSION

We found that lymph node metastasis detected on F-FDG PET/CT correlated positively with 1-year recurrence after surgical resection in patients with peripheral ICC.

Hepatic radioembolization as a bridge to liver surgery

Treatment of oncologic disease has improved significantly in the last decades and in the future a vast majority of cancer types will continue to increase worldwide. As a result, many patients are confronted with primary liver cancers or metastatic liver disease. Surgery in liver malignancies has steeply improved and curative resections are applicable in wider settings, leading to a prolonged survival. Simultaneously, radiofrequency ablation (RFA) and liver transplantation (LTx) have been applied more commonly in oncologic settings with improving results. To minimize adverse events in treatments of liver malignancies, locoregional minimal invasive treatments have made their appearance in this field, in which radioembolization (RE) has shown promising results in recent years with few adverse events and high response rates. We discuss several other applications of RE for oncologic patients, other than its use in the palliative setting, whether or not combined with other treatments. This review is focused on the role of RE in acquiring patient eligibility for radical treatments, like surgery, RFA, and LTx. Inducing significant tumor reduction can downstage patients for resection or, through attaining stable disease, patients can stay on the LTx waiting list. Hereby, RE could make a difference between curative of palliative intent in oncologic patient management. Prior to surgery, the future remnant liver volume might be inadequate in some patients. In these patients, forming an adequate liver reserve through RE leads to prolonged survival without risking post-operative liver failure and minimizing tumor progression while inducing hypertrophy. In order to optimize results, developments in procedures surrounding RE are equally important. Predicting the remaining liver function after radical treatment and finding the right balance between maximum tumor irradiation and minimizing the chance of inducing radiation-related complications are still challenges.

The prognostic value of 18F-FDG PET/CT for hepatocellular carcinoma treated with transarterial chemoembolization (TACE)

18F-Fluoro-deoxyglucose (FDG) PET/CT can be used to monitor the biological behavior of hepatocellular carcinoma (HCC). Baseline PET/CT has prognostic value in HCC patients, but there is litter knowledge of the PET/CT changes after treatment. We evaluated 27 HCC patients treated with transarterial chemoembolization (TACE) from June 2011 to July 2012, and we investigated the prognostic value of PET/CT. Patients were followed up with regular clinical and laboratory examinations and contrast-enhanced spiral computed tomography (CT). Furthermore, PET/CT assessments were collected and analyzed before (range 1~15 d) and after the first month of TACE (range, 27~45 d). We tested the prognostic value of the tumor standardized uptake value (TSUV) and normal liver SUV(LSUV) according to the VOI (volume of interest). The SUVs were used to assess the relationship between the treatment response and survival. To assess their prognostic value, we evaluated the areas under the receiver operating characteristic (ROC) curves of different SUVs for predicting survival. Finally, the median overall survival (OS) and time to progression (TTP) for 27 patients were 15.4 months (95%CI, 3.3-27.5 months) and 11.4 months (95%CI, 6.7-16.1 months), respectively. The ΔTSUVmax%, based on the VOI, had the highest discriminative prognostic value and the cutoff PET/CT response was 0.1 with a sensitivity of 100% and a specificity of 95.2%. The OS was significantly better in the PET/CT response group than in the PET/CT non-response group (p=0.025). In conclusion, an early interim PET/CT after TACE may have prognostic value for HCC patients treated with TACE, and the ΔTSUVmax% may help in determining the HCCs viability in patients with high baseline and follow-up18F-FDG uptake.

Assessment of [(18)F]-fluoroacetate PET/CT as a tumor-imaging modality: preclinical study in healthy volunteers and clinical evaluation in patients with liver tumor

OBJECTIVE

Although [(18)F]-FDG is a useful oncologic PET tracer, FDG uptake is known to be low in a certain type of hepatocellular carcinoma (HCC). [(18)F]-fluoroacetate ((18)F-FACE) is an [(18)F] fluorinated acetate, which is known to be converted into fatty acids, incorporated in membrane and is expected to be a promising oncologic PET tracer. The aim of this study was to evaluate the usefulness of (18)F-FACE as an oncologic PET tracer in preclinical study in healthy volunteers and in patients with liver tumors.

METHODS

Twenty-four healthy volunteers (age 48.2 ± 12.9 years old; 15 male and 9 female) and ten patients with liver tumor (age 72.1 ± 7.0 years old; 6 male and 4 female) were included. We performed whole-body static PET/CT scan using (18)F-FACE (n = 34) and (18)F-FDG (n = 5 for volunteers, n = 8 for patients) on each day, respectively. Qualitative analysis and quantitative analysis of tumors (5 HCCs, 1 cholangiocellular carcinoma, 4 metastatic tumors from colon cancer and P-NET) were performed using SUVmax and tumor-to-normal liver ratio (TNR).

RESULTS

In healthy volunteers, (18)F-FACE was metabolically stable in vivo and its biodistribution was almost similar to blood pool, basically uniformly independent of age and gender during PET scan time (up to 3 h). Normal physiological uptake of (18)F-FACE at each organ including liver (SUVmean 1.8 ± 0.2) was lower than that of blood pool (SUVmean 2.3 ± 0.3) at 1 h after injection. Chronic inflammatory uptake around femur of post-operative state of femoral osteotomy and faint uptake of benign hemangioma were observed in a case of healthy volunteer. (18)F-FACE (SUVmax 2.7 ± 0.6, TNR 1.5 ± 0.4) of liver tumors was significantly lower than those of (18)F-FDG uptake (6.5 ± 4.2, 2.6 ± 1.7, respectively). In qualitative analysis, (18)F-FDG was positive in 4 tumors (3 HCCs, 1 CCC) and negative in the other 6 tumors, while (18)F-FACE was also positive in 4 tumors which were the same tumors with positive (18)F-FDG uptake.

CONCLUSIONS

Biodistribution of (18)F-FACE was appropriate for oncologic imaging. Tumor (18)F-FACE uptake was positive in four patients with HCC and CCC, but the uptake pattern was similar to (18)F-FDG. Further evaluation was needed.

Clinical application of 18F-fluorodeoxyglucose positron emission tomography for assessment and evaluation after therapy for malignant hepatic tumor

Positron emission tomography (PET) is widely available and its application with 2-[(18)F] fluoro-2-deoxy-D-glucose ((18)F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumors, and monitoring the therapeutic efficacy in hepatic malignancies. Recently, investigators have measured glucose utilization in liver tumors using (18)F-FDG and positron emission tomography/computer tomography (PET/CT) in order to establish a diagnosis of tumors, assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. The PET/CT with (18)F-FDG may further enhance the hepatic malignancy diagnostic algorithm by accurate diagnosis, staging, restaging and evaluating its biological characteristics, which can benefit the patients suffering from primary and metastatic hepatic tumors such as hepatocellular carcinoma (HCC), cholangiocarcinoma (CCC), and metastatic liver tumor.

Frequent alteration of the protein synthesis of enzymes for glucose metabolism in hepatocellular carcinomas

BACKGROUND

Cancer cells show enhanced glycolysis and inhibition of oxidative phosphorylation, even in the presence of sufficient oxygen (aerobic glycolysis). Glycolysis is much less efficient for energy production than oxidative phosphorylation, and the reason why cancer cells selectively use glycolysis remains unclear.

METHODS

Biospecimens were collected from 45 hepatocellular carcinoma patients. Protein samples were prepared through subcellular localization or whole-cell lysis. Protein synthesis was measured by SDS-PAGE and immunoblotting. mRNA transcription was measured using quantitative RT-PCR. Statistical correlation among immunoblotting data and clinicolaboratory factors were analyzed using SPSS.

RESULTS

Enzymes for oxidative phosphorylation (SDHA and SDHB) were frequently decreased (56 and 48 % of patients, respectively) in hepatocellular carcinomas. The lowered amount of the SDH protein complex was rarely accompanied by stabilization of HIF1α and subsequent activation of the hypoxia response. On the other hand, protein synthesis of G6PD and TKT, enzymes critical for pentose phosphate pathway (PPP), was increased (in 45 and 55 % of patients, respectively), while that of ALDOA, an enzyme for mainstream glycolysis, was eliminated (in 55 % of patients). Alteration of protein synthesis was correlated with gene expression for G6PD and TKT, but not for TKTL1, ALDOA, SDHA or SDHB. Augmented transcription and synthesis of PPP enzymes were accompanied by nuclear accumulation of NRF2.

CONCLUSION

Hepatocellular carcinomas divert glucose metabolism to the anabolic shunt by activating transcription factor NRF2.

A survival benefit of major hepatectomy for hepatocellular carcinoma identified by preoperative [18F] fluorodeoxyglucose positron emission tomography in patients with well-preserved hepatic function

AIMS

Hepatic resection can cure hepatocellular carcinoma (HCC). However, the optimal extent of resection remains controversial. Major hepatectomy could minimize a tumor recurrence, but it is harmful due to decreased hepatic functional reserve. [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) scans are known as their reflection tumor differentiation and biological activity in HCC. To evaluate a benefit of major hepatectomy for HCC, we performed this retrospective analysis in patients with well-preserved hepatic function, and further analyzed in the subset identified by preoperative FDG-PET.

METHODS

We reviewed the medical records of 189 patients with HCC who underwent curative resection between August 2004 and December 2010 at two institutes. All patients underwent anatomical resection, either by major or minor hepatectomy.

RESULTS

Median overall survival did not differ significantly between the major and minor hepatectomy groups (29.4 versus 26.3 months, p = 0.269). However, the major hepatectomy group had a better recurrence-free survival (24.5 versus 19.9 months, p = 0.004). On multivariate analysis, the presence of intrahepatic metastasis independently predicted overall survival (p = 0.009), but other examined variables did not. Overall survival and recurrence-free survival were significantly better following major hepatectomy rather than minor hepatectomy in patients whose preoperative FDG-PET indicated that the maximum standardized uptake value of the tumor (SUVtumor) was ≥4 and the tumor-to-nontumor SUV ratio (TNR) was ≥1.5.

CONCLUSIONS

Our findings suggest that preoperative FDG-PET may be useful in identifying patients with favorable hepatic reserve who are most likely to benefit from major rather than minor hepatectomy.

Comparison of the effectiveness of MRI perfusion and fluorine-18 FDG PET-CT for differentiating radiation injury from viable brain tumor: a preliminary retrospective analysis with pathologic correlation in all patients

OBJECTIVES

Differentiating radiation injury from viable tumor is important for optimizing patient care. Our aim was to directly compare the effectiveness of fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) and dynamic susceptibility-weighted contrast-enhanced (DSC) magnetic resonance (MR) perfusion in differentiating radiation effects from tumor growth in patients with increased enhancement following radiotherapy for primary or secondary brain tumors.

MATERIALS AND METHODS

We retrospectively identified 12 consecutive patients with primary and secondary brain tumors over a 1-year period that demonstrated indeterminate enhancing lesions after radiotherapy and that had undergone DSC MR perfusion, FDG PET-CT, and subsequent histopathologic diagnosis. The maximum standardized uptake value (SUV) of the lesion (SUVlesion max), SUVratio (SUVlesion max/SUVnormal brain), maximum relative cerebral blood volume, percentage of signal intensity recovery, and relative peak height were calculated from the positron emission tomography and MR perfusion studies. A prediction of tumor or radiation injury was made based on these variables while being blinded to the results of the surgical pathology.

RESULTS

SUVratio had the highest predictive value (area under the curve=0.943) for tumor progression, although this was not statistically better than any MR perfusion metric (area under the curve=0.757-0.829).

CONCLUSIONS

This preliminary study suggests that FDG PET-CT and DSC MR perfusion may demonstrate similar effectiveness for distinguishing tumor growth from radiation injury. Assessment of the SUVratio may increase the sensitivity and specificity of FDG PET-CT for differentiating tumor and radiation injury. Further analysis is needed to help define which modality has greater predictive capabilities.

Predictive biomarkers of antiangiogenic therapy for advanced hepatocellular carcinoma: where are we?

Antiangiogenic therapy, especially treatment with sorafenib, is the primary treatment for patients with advanced hepatocellular carcinoma (HCC). However, the efficacy of such therapy is modest, with low objective response rates and limited prolongation of survival times. Several researchers have investigated predictive biomarkers to help identify patients who can benefit most from antiangiogenic therapy. The largest study on this topic to date was based on the pivotal phase III study of sorafenib (the SHARP study) and did not find any plasma markers that could predict the efficacy of sorafenib. Other studies based on single-arm phase II clinical trials found some potential predictive markers, such as early alpha-fetoprotein response, the serum insulin-like growth factor-1 level at baseline, and the volume transfer constants of dynamic contrast-enhanced magnetic resonance imaging. These findings require validation by further studies. Identifying predictive biomarkers of antiangiogenic therapy for HCC remains challenging and warrants further investigations.

Hepatocellular carcinoma and gastroenteropancreatic neuroendocrine tumors: potential role of other positron emission tomography radiotracers

18F-Fluorodeoxyglucose avidity for gastroenteropancreatic neuroendocrine tumors and hepatocellular carcinoma is variable, depending on the underlying tumor biology. Experience with non-fluorodeoxyglucose (FDG) tracers (eg, 18F-labeled amine precursors l-dihydroxyphenylalanine and 68Ga-DOTA-peptides for gastroenteropancreatic neuroendocrine tumors and radiolabeled acetate or choline for hepatocellular carcinoma) is evolving and expanding rapidly. This article reviews the role of FDG and non-FDG radiotracers in the imaging evaluation of patients with gastroenteropancreatic neuroendocrine tumors or hepatocellular carcinoma.

(18)F-FDG-PET/CT predicts early tumor recurrence in living donor liver transplantation for hepatocellular carcinoma

The prognosis including (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) for the early recurrence for hepatocellular carcinoma (HCC) after living donor liver transplantation (LDLT) was not well established. Consecutive patients who underwent (18)F-FDG-PET/CT and subsequent LDLT for HCC from March 2005 to June 2011 were enrolled. The 191 patients with a median follow-up of 26.1 months were evaluated. There were 20 patients (10.5%) with early recurrence (≤6 months), 18 patients (9.4%) with late recurrence (>6 months), and 153 patients (80.1%) with no recurrence. Fifty-five patients (28.8%) displayed increased PET/CT tumor uptake. Three-year overall and disease-free survival for PET/CT-positive patients were 65.5% and 57.1%, respectively, while PET/CT-negative patients showed respective values of 89.8% and 86.8% (P = 0.001 vs. P < 0.001). Tumor variables associated with PET/CT-positive finding were preoperative AFP level, Milan, UCSF criteria, maximum tumor size, total tumor size, differentiation, vascular invasion, and serosal invasion. PET/CT-positive status was identified as an independent prognostic factor for disease-free survival influencing early recurrence in multivariable analysis (HR 3.945, 95% CI 1.196-13.016, P = 0.024). (18)F-FDG-PET/CT is an independent and significant predictor of early tumor recurrence in LDLT for HCC.

A pilot comparison of 18F-fluorodeoxyglucose and 18F-fluorocholine PET/CT to predict early recurrence of unifocal hepatocellular carcinoma after surgical resection

OBJECTIVE

Presurgical identification of patients at high risk for early recurrence of hepatocellular carcinoma (HCC) after resection could warrant additional therapies. F-fluorodeoxyglucose (FDG) uptake by the tumour on preoperative PET can predict HCC recurrence after resection as effectively as poor differentiation or presence of microvascular invasion (MVI) on postsurgical histology. A better sensitivity for the detection of HCC nodules has been reported with F-fluorocholine (FCH), a PET tracer of lipid metabolism. This pilot study aimed to compare preoperative FDG and FCH PET/CT for predicting early recurrence of unifocal HCC, occurring within 6 months after surgical resection.

METHODS

FDG and FCH tumour uptakes were assessed on preoperative PET/CT by two masked readers. On FCH PET/CT, a photopenic lesion and a hot focus were considered as indicative of malignancy. During postoperative follow-up, recurrence was searched for by regularly performing CT and MRI.

RESULTS

In 11 consecutive HCC patients, the detection rate was greater with FCH (80%) than with FDG (27%). After resection, the overall recurrence rate was 55%. Early recurrence occurred in four patients, who were the only ones with an FDG-positive and FCH-photopenic tumour, with a significant reduction in disease-free survival. On postsurgical histology, those four patients also presented with MVI and satellite nodules. Histological differentiation and capsule disruption appeared less accurate than PET/CT or MVI in predicting early recurrence.

CONCLUSION

In unifocal HCC, the FCH photopenic pattern was associated with MVI and predicted early HCC recurrence after surgical resection as accurately as did an FDG uptake. Larger studies with FCH are warranted.

Diagnostic value for extrahepatic metastases of hepatocellular carcinoma in positron emission tomography/computed tomography scan

AIM: To evaluated the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan in diagnosis of hepatocellular carcinoma (HCC) and extrahepatic metastases.

METHODS: A total of 138 patients with HCC who had both conventional imaging modalities and ¹⁸F-FDG PET/CT scan done between November 2006 and March 2011 were enrolled. Diagnostic value of each imaging modality for detection of extrahepatic metastases was evaluated. Clinical factors and tumor characteristics including PET imaging were analyzed as indicative factors for metastases by univariate and multivariate methods.

RESULTS: The accuracy of chest CT was significantly superior compared with the accuracy of PET imaging for detecting lung metastases. The detection rate of metastatic pulmonary nodule ≥ 1 cm was 12/13 (92.3%), when < 1 cm was 2/10 (20%) in PET imaging. The accuracy of PET imaging was significantly superior compared with the accuracy of bone scan for detecting bone metastases. In multivariate analysis, increased tumor size (≥ 5 cm) (P = 0.042) and increased average standardized uptake value (SUV) uptake (P = 0.028) were predictive factors for extrahepatic metastases. Isometabolic HCC in PET imaging was inversely correlated in multivariate analysis (P = 0.035). According to the receiver operating characteristic curve, the optimal cutoff of average SUV to predict extrahepatic metastases was 3.4.

CONCLUSION: ¹⁸F-FDG PET/CT scan is invaluable for detection of lung metastases larger than 1 cm and bone metastases. Primary HCC having larger than 5 cm and increased average SUV uptake more than 3.4 should be considered for extrahepatic metastases.

The role of preoperative [18F]fluorodeoxyglucose positron emission tomography in predicting early recurrence after curative resection of hepatocellular carcinomas

PURPOSE

(18)F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) scan reflects tumor differentiation and predicts clinical outcome in patients with hepatocellular carcinoma (HCC). We investigated the correlation of PET scans with tumor differentiation and early tumor recurrence (time-to-recurrence <1 year).

METHODS

We reviewed the medical records of 93 patients with HCC who underwent curative resection at our hospital from August 2004 through December 2008. PET scans were performed preoperatively, and the maximum standardized uptake value of the tumor (SUV(tumor)) and the tumor-to-non-tumor SUV ratio (TNR) were calculated from FDG uptake.

RESULTS

Twenty-six (27.9%) had recurrences and 12 of them (46.2%) had early recurrences. SUV(tumor) and TNR correlated strongly with tumor differentiation (p < 0.001). Early recurrence-free and the overall survival rates in the low TNR group (TNR <2.0) were higher than in the high TNR group (TNR ≥2.0) (p = 0.015, p = 0.013). According to univariate analysis, predictors of early tumor recurrence were large tumor size (≥5 cm), high TNR (≥2), high SUV(tumor) (≥4), and high Edmoson-Steiner grade. However, on multivariate analysis, none of the examined factors were statistically significant independent predictor.

CONCLUSION

PET scans reflect tumor differentiation in HCCs. Because high TNR (TNR ≥2) and SUV(tumor) (SUV ≥4) were these cutoff point significant predictors in univariate analysis, future studies with more statistical power are needed to assess the significance.