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

Value of PET/CT in the management of primary hepatobiliary tumors, part 2

OBJECTIVE

Primary hepatobiliary malignancies consist of hepatocellular carcinoma, cholangiocarcinoma, and gallbladder cancer. Benign hepatic lesions include hepatic cysts, hemagiomas, adenomas, and focal nodular hyperplasias. The utility of PET/CT in imaging primary hepatobiliary lesions varies according to the type and location of the lesion.

CONCLUSION

There is a consistent benefit to the use of PET/CT for detection and staging, and it ultimately helps to establish the best course of treatment and to determine prognosis. In addition, PET/CT is very useful in local ablative and systemic therapy assessment and surveillance for hepatobiliary malignancies.

Prognostic value of 18F-FDG PET for hepatocellular carcinoma patients treated with sorafenib

BACKGROUND

Sorafenib (Nexavar) is an orally active multikinase inhibitor that is approved for the treatment of hepatocellular carcinoma (HCC). In this study, we used (18) F-2-fluoro-2-deoxyglucose ((18) F-FDG) with positron emission tomography (PET) to predict the treatment outcome of sorafenib in patients with advanced HCC.

MATERIALS AND METHODS

A total of 29 patients with HCC were included. Baseline (18) F-FDG PET scans were performed a median of 14 days before sorafenib treatment. Sorafenib was administered orally at a dose of 400 mg twice daily. For statistical analysis, the standardized uptake value (SUV) of the most hypermetabolic lesion was obtained and assigned as the SUVmax for each patient.

RESULTS

Among 29 patients, one patient achieved partial remission and 14 patients showed stable disease. The overall survival (OS) and progression free survival (PFS) were 5.1 months [95% confidence interval (CI): 0.0-12.0] and 3.8 months (95% CI: 1.4-6.2). The multivariate analysis of OS showed that four indices, Eastern Cooperative Oncology Group performance status, α-fetoprotein (AFP) concentration, portal vein thrombosis and SUVmax were significant prognostic factors (P=0.030, P=0.024, P=0.020 and P=0.015 respectively). AFP concentration and SUVmax were independent prognostic factors for PFS, too (P=0.003 and P=0.026 respectively). When the patients were divided into two groups: low SUVmax (n=10; <5.00) and high SUVmax (n=19;≥ 5.00), the low SUV group showed significantly longer OS and PFS (P=0.023 and P=0.042 respectively).

CONCLUSION

Our study showed that the degree of FDG uptake is an independent prognostic factor in patients with HCC who undergo sorafenib treatment.

Positron emission tomography for staging and assessment of tumor response of hepatic malignancies

(18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a useful functional imaging method that complements conventional anatomic imaging modalities for screening patients with colorectal hepatic metastases and hepatocellular cancer to determine their suitability for interventional procedures. FDG PET is more sensitive in detecting colorectal cancer than hepatocellular cancer (~90% versus ~50%). The likelihood of detecting hepatic malignancy with FDG PET rapidly diminishes for lesions smaller than 1 cm. The greatest value of FDG PET in these patients is in excluding extrahepatic disease that might lead to early recurrence after interventional therapy. Promising results have been reported with FDG PET that may show residual (local) or recurrent disease before conventional imaging methods in patients receiving interventional therapy. For patients with colorectal hepatic metastases, many investigators believe that patients with PET evidence of recurrent hepatic disease should receive additional treatment even when there is no confirmatory evidence present on other methodologies. For patients with hepatocellular cancer no conclusions regarding the value of FDG PET for assessment of response to interventional therapy can be reached as there is almost no published data.

Clinical applications of positron emission tomography in hepatic tumors

Fluorodeoxyglucose (FDG), which allows the evaluation of glucose metabolism, is widely used for tumor diagnosis using positron emission tomography (PET). FDG-PET, which is used for the diagnosis of intrahepatic tumor lesions, shows high FDG accumulation in cholangiocellular carcinoma (CCC) and metastatic liver cancer. FDG-PET shows high FDG accumulation in moderately or poorly differentiated hepatocellular carcinoma (HCC) and is useful for the diagnosis of extrahepatic HCC metastases and recurrences. However, because the imaging method frequently shows low FDG accumulation in well-differentiated HCC, it is not very useful for that diagnosis. For the diagnosis of well-differentiated HCC, F-18 fluorocholine for evaluation of phospholipid metabolism and C-11 acetate for evaluation of free fatty acid metabolism are useful in the diagnosis of that HCC. It is expected that the combination of these PET agents will enhance the diagnostic performance of FDG-PET for HCC in the future. The problem of a lack of anatomical information is being resolved with the development of the use of PET in combination with computed tomography or magnetic resonance imaging. For the problem of low resolution, PET devices using semiconductors have been developed.

Prognostic implication of (18)F FDG-PET in patients with extrahepatic metastatic hepatocellular carcinoma undergoing systemic treatment, a retrospective cohort study

PURPOSE

The role of (18)F FDG-PET in hepatocellular carcinoma (HCC) has not been firmly established. We conducted this study to investigate the clinical implication of SUVmax on (18)F FDG-PET as a prognostic factor in patients with HCC, especially in the metastatic setting.

METHODS

HCC patients with extrahepatic metastatic lesions were enrolled that were evaluated by (18)F FDG-PET before palliative systemic therapy, between January 2002 and December 2009 at the Seoul National University Hospital. We retrospectively analyzed the clinical outcome and the value of the SUVmax.

RESULTS

A total of 25 patients (men, 88.0%) were enrolled. The response rate and disease control rate was 18.2% (95% CI: 2.1-34.3) and 32.0% (95% CI: 16.3-56.5), respectively. The progression-free survival (PFS) and overall survival (OS) were 2.3 months (95% CI: 1.1-3.4) and 14.2 months (95% CI: 9.1-19.2), respectively. The univariate analysis of OS showed that SUVmax and alphafetoprotein (AFP) were significant prognostic factors (P = 0.023 and P = 0.006, respectively). The multivariate analysis of OS showed that SUVmax and AFP were significant prognostic factors (P = 0.008 and P = 0.006, respectively). SUVmax and AFP were independent prognostic factors for PFS, too (P = 0.010 and P = 0.016, respectively). When the patients were divided according to the SUVmax and AFP, the patients with an SUVmax < 4.9 and an AFP ≤ 400 ng/ml showed longer OS and PFS than the patients with SUVmax ≥ 4.9 or AFP > 400 ng/ml (26.7 months vs. 9.3 months, P < 0.001 and 5.6 months vs. 1.7 months, P = 0.012, respectively).

CONCLUSIONS

The SUVmax of the (18)F FDG-PET has a prognostic value for OS and PFS in patients with metastatic HCC undergoing systemic therapy. The combined analysis of the SUVmax with AFP might provide more detailed prognostic information.

Contribution of biomarkers and imaging in the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most frequent malignant tumour of the liver. HCC prognosis is dependent on the determination of the tumour stage by conventional imaging and early screening. However, patient survival can vary with the same tumour stage. Biomarkers thus have a role in providing an earlier diagnosis, better prognosis classification before treatment and classification prognosis during treatment. In this review article, we will provide a successive, detailed description of the serum, pathological, molecular and imaging markers of HCC.

Usefulness of positron emission tomography with fluorine-18-fluorodeoxyglucose in predicting treatment response in unresectable hepatocellular carcinoma patients treated with external beam radiotherapy

PURPOSE

To assess the significance of the ratio between standardized uptake values (SUV) of tumor and normal liver tissue obtained from positron emission tomography with fluorine-18-fluorodeoxyglucose (FDG-PET) in predicting the response of hepatocellular carcinoma (HCC) patients treated with external beam radiotherapy (EBRT).

METHODS AND MATERIALS

We retrospectively analyzed 35 HCC patients who were treated with EBRT between January 2004 and June 2007. All patients underwent FDG-PET in which SUV values were obtained from tumor and normal liver tissues and were used to calculate the ratios (SUV(Tumor)/SUV(Liver)). After FDG-PET, patients received liver treatment including concurrent chemoradiation, transarterial chemoembolization plus RT, or intraarterial chemotherapy plus RT. Using three-dimensional conformal RT, median dose of 45 Gy was delivered in conventional fractions. Patients underwent abdominal/pelvic CT 1 month after RT, and treatment responses were evaluated according to the Response Evaluation Criteria in Solid Tumors criteria.

RESULTS

Patients were divided into high-SUV ratio group (n = 20) and low-SUV ratio group (n = 15) according to SUV ratio at a cutoff value of 2.5. Objective responses consisting of either complete response (CR) or partial response (PR) were observed in 16 and 6 patients (46% vs. 17%, p = 0.015), respectively; median survivals after RT were 8 months and 5 months (p = 0.41) for the high-SUV ratio group and the low-SUV ratio group, respectively. Rates of intrahepatic metastases (9% vs. 11%, p = 0.39) and distant metastases (32% vs. 32%, p = 0.27) showed no significant difference between two groups.

CONCLUSIONS

External beam RT for HCC patients with higher SUV ratios resulted in higher response rates than for patients with lower SUV ratios. Treatment of HCC with higher SUV ratios did not result in increased survival; high rates of intrahepatic and distant metastases in both SUV groups may have affected patient survival. SUV ratios from pre-RT FDG-PET may be beneficial for selecting patients who are likely to respond to EBRT for unresectable HCC.

Asian Pacific Association for the Study of the Liver consensus recommendations on hepatocellular carcinoma

INTRODUCTION

The Asian Pacific Association for the Study of the Liver (APASL) convened an international working party on the management of hepatocellular carcinoma (HCC) in December 2008 to develop consensus recommendations.

METHODS

The working party consisted of expert hepatologist, hepatobiliary surgeon, radiologist, and oncologist from Asian-Pacific region, who were requested to make drafts prior to the consensus meeting held at Bali, Indonesia on 4 December 2008. The quality of existing evidence and strength of recommendations were ranked from 1 (highest) to 5 (lowest) and from A (strongest) to D (weakest), respectively, according to the Oxford system of evidence-based approach for developing the consensus statements.

RESULTS

Participants of the consensus meeting assessed the quality of cited studies and assigned grades to the recommendation statements. Finalized recommendations were presented at the fourth APASL single topic conference on viral-related HCC at Bali, Indonesia and approved by the participants of the conference.

Asian Pacific Association for the Study of the Liver consensus recommendations on hepatocellular carcinoma

INTRODUCTION

The Asian Pacific Association for the Study of the Liver (APASL) convened an international working party on the management of hepatocellular carcinoma (HCC) in December 2008 to develop consensus recommendations.

METHODS

The working party consisted of expert hepatologist, hepatobiliary surgeon, radiologist, and oncologist from Asian-Pacific region, who were requested to make drafts prior to the consensus meeting held at Bali, Indonesia on 4 December 2008. The quality of existing evidence and strength of recommendations were ranked from 1 (highest) to 5 (lowest) and from A (strongest) to D (weakest), respectively, according to the Oxford system of evidence-based approach for developing the consensus statements.

RESULTS

Participants of the consensus meeting assessed the quality of cited studies and assigned grades to the recommendation statements. Finalized recommendations were presented at the fourth APASL single topic conference on viral-related HCC at Bali, Indonesia and approved by the participants of the conference.

The role of (18)F-fluorodeoxyglucose positron emission tomography in the diagnosis, staging, and follow-up of cholangiocarcinoma

(18)F-Fluorodeoxyglucose positron emission tomography ((18)FDG-PET) is a new diagnostic technique for the diagnosis and staging of cholangiocarcinoma. For diagnosis of a primary cholangiocarcinoma, (18)FDG-PET seems to be helpful to discriminate between malignant and benign lesions. However, the accuracy of (18)FDG-PET seems to be dependent on the anatomic location, growth pattern, and pathologic characteristics of the lesion. It has been proved that the accuracy of (18)FDG-PET is limited to detection of extrahepatic, infiltrating, and mucinous cholangiocarcinomas. Due to its lower sensitivity, (18)FDG-PET provides complementary rather than confirmative information in the diagnosis of regional lymph node metastasis. In contrast, it has high accuracy in detecting unsuspected distant metastases. The role of (18)FDG-PET in detecting cancer recurrence, monitoring treatment response, and predicting prognosis is still controversial.

Quantitative analysis of tumor growth rate and changes in tumor marker level: specific growth rate versus doubling time

BACKGROUND

Doubling time (DT) of tumor volume has been widely used to estimate the growth rate of tumors. However, DT gives incorrect estimates of the average growth rate of tumors when the uncertainty of growth rate is considerable. Specific growth rate (SGR) is less affected by uncertainties and is a more relevant parameter. Optimized imaging techniques and prolonged interval between observations can reduce the uncertainty of growth rate estimation. DT is also used for defining changes in tumor marker level. The aim of this study was to compare DT and SGR as measures of growth rate when the uncertainty is negligible.

METHODS

Mathematical analysis and computer simulations were carried out assuming no uncertainty of growth rate estimation. Data from two previously published clinical studies were assessed by both variables.

RESULTS

Due to the non-linear relationship between DT and SGR, using these variables does not give similar results. The variation of DT is not uniformly indicating variations of the growth rate. DT largely overestimates the difference in growth rate of slowly growing tumors and underestimates the difference in growth rate of rapidly growing tumors. On the other hand, SGR uniformly indicates the difference between growth rates throughout all ranges. Quantitative analysis of clinical observations can lead to contradictory results depending on the variable used for growth rate.

CONCLUSION

The growth rate of tumor volume should be expressed by SGR, or percentage increase per unit time, regardless of the level of the uncertainty of growth rate estimation. This conclusion is also valid for changes in tumor marker level, whether it is correlated with the growth rate of tumor volume or not.

Predictive value of 18F-FDG PET and somatostatin receptor scintigraphy in patients with metastatic endocrine tumors

The treatment of metastatic neuroendocrine tumors depends on the aggressiveness of the disease. We wanted to know whether (18)F-FDG PET and somatostatin receptor scintigraphy (SRS) can predict early disease progression and patient survival.

METHODS

We undertook a prospective study of patients with metastatic neuroendocrine tumor diagnosed between September 2003 and January 2006. After obtaining signed informed consent from the patients, we performed CT, SRS, and (18)F-FDG PET and reviewed histologic data. CT was repeated every 3 mo to assess the risk of early progressive disease (first 6 mo), progression-free survival, and overall survival.

RESULTS

Thirty-eight patients (mean age, 60 +/- 15 y) were included. Histologically, 4 patients had a high-grade and 34 a low-grade tumor. The results of (18)F-FDG PET and SRS were positive in 15 and 27 patients. The 2-y overall survival and progression-free survival were 73% and 45%; 16 patients had early progressive disease. Most (18)F-FDG PET-positive patients had early progressive disease (14/15, vs. 2/23 (18)F-FDG PET-negative patients), and most SRS-negative patients had early progressive disease (9/11, vs. 7/27 SRS-positive patients); (18)F-FDG PET gave excellent negative and positive predictive values of 91% and 93%; (18)F-FDG PET results correlated with progression-free survival (P < 0.001) and overall survival (P < 0.001) even when only low-grade tumors were considered. SRS was associated with progression-free survival (P < 0.001) and overall survival (P < 0.03). At multivariate analysis, only (18)F-FDG PET was predictive of progression-free survival.

CONCLUSION

(18)F-FDG PET exhibits excellent predictive values for early tumor progression. (18)F-FDG PET and SRS results correlate with progression-free survival and overall survival even for histologically low-grade tumors. These explorations could be included in the initial work-up for metastatic neuroendocrine tumor.

Prognostic indicators in hepatocellular carcinoma: a systematic review of 72 studies

BACKGROUND

Although there are many studies of the predictors of death in hepatocellular carcinoma (HCC), most combine patients with and without cirrhosis and many combine those with compensated and decompensated cirrhosis.

OBJECTIVE

To perform a systematic review of the literature evaluating the predictors of death in patients with cirrhosis and HCC and to evaluate whether the predictors differ between patients with compensated and decompensated cirrhosis.

INCLUSION CRITERIA

(i) publication in English, (ii) adult patients, (c) >80% of the patients had cirrhosis, (iv) follow-up >6 months and (v) multivariable analysis. Quality was based on the accepted quality criteria for prognostic studies.

RESULTS

Of the 1106 references obtained, 947 were excluded because they did not meet the inclusion criteria. A total of 23 968 patients were included in 72 studies (median, 177/study); 77% male, median age 64, 55% Child-Pugh class A. The most robust predictors of death were portal vein thrombosis, tumour size, alpha-foetoprotein and Child-Pugh class. Sensitivity analysis using only 15 'good' studies and 22 studies in which all patients had cirrhosis yielded the same variables. In the studies including mostly compensated or decompensated patients, the predictors were both liver and tumour related. However, these studies were few and the results were not robust.

CONCLUSIONS

This systematic review of 72 studies shows that the most robust predictors of death in patients with cirrhosis and HCC are tumour related and liver related. Future prognostic studies should include these predictors and should be performed in specific patient populations to determine whether specific prognostic indicators are more relevant at different stages of cirrhosis.

A prospective evaluation of 18F-FDG and 11C-acetate PET/CT for detection of primary and metastatic hepatocellular carcinoma

Because (18)F-FDG PET has insufficient sensitivity for the detection of hepatocellular carcinoma (HCC), (11)C-acetate PET has been proposed as another technique for this use. We prospectively evaluated the value of PET/CT using these 2 tracers for the detection of primary and metastatic HCC.

METHODS

One hundred twelve patients (99 with HCC, 13 with cholangiocellular carcinoma) underwent biopsy and (18)F-FDG and (11)C-acetate PET/CT.

RESULTS

The overall sensitivities of (18)F-FDG, (11)C-acetate, and dual-tracer PET/CT in the detection of 110 lesions in 90 patients with primary HCC were 60.9%, 75.4%, and 82.7%, respectively. Elevated serum alpha-fetoprotein levels, an advanced tumor stage, portal vein tumor thrombosis, large tumors, and multiple tumors were significantly associated with positive (18)F-FDG PET/CT results. Uptake of (11)C-acetate was associated with large and multiple tumors. For (18)F-FDG, the sensitivities according to tumor size (1-2, 2-5, and >/=5 cm) were 27.2%, 47.8%, and 92.8%, respectively; for (11)C-acetate, these respective values were 31.8%, 78.2%, and 95.2%. (18)F-FDG was more sensitive in the detection of poorly differentiated HCC. Overall survival was lower in patients with (18)F-FDG PET/CT positive for all indexed lesions than in those with FDG negative or partially positive through the entire follow-up period. In analysis based on biopsied lesions, the sensitivity of (18)F-FDG PET/CT was 64.4% for primary HCC and 84.4% for (11)C-acetate PET/CT. The overall sensitivities of (18)F-FDG, (11)C-acetate, and dual-tracer PET/CT for 35 metastatic HCCs were 85.7%, 77.0%, and 85.7%, respectively. There was no significant difference in the sensitivity of tracers according to metastatic tumor size, location, or differentiation.

CONCLUSION

The addition of (11)C-acetate to (18)F-FDG PET/CT increases the overall sensitivity for the detection of primary HCC but not for the detection of extrahepatic metastases. (18)F-FDG, (11)C-acetate, and dual-tracer PET/CT have a low sensitivity for the detection of small primary HCC, but (18)F-FDG PET/CT has a relatively high sensitivity for the detection of extrahepatic metastases of HCC.

Usefulness of 18F-fluorodeoxyglucose positron emission tomography in differential diagnosis and staging of cholangiocarcinomas

BACKGROUND AND AIM

(18)F-Fluoro-2-deoxy-d-glucose positron emission tomography ((18)FDG-PET) is promising for diagnosis and treatment of various malignancies. The aim of this study was to evaluate the clinical usefulness of (18)FDG-PET in differential diagnosis and staging of cholangiocarcinomas according to the intrahepatic, perihilar and common bile duct lesions and to compare with computerized tomography (CT) scan.

METHODS

From January 2000 to September 2003, 54 patients with suspected cholangiocarcinoma underwent abdominal CT scan and (18)FDG-PET within a 2-week period. The PET images were analyzed visually and semiquantitatively.

RESULTS

The overall accuracy of (18)FDG-PET for discriminating malignant diseases of bile duct from benign conditions was slightly higher than that of CT scan (88.9% vs 81.5%). The sensitivity of (18)FDG-PET in perihilar cholangiocarcinoma was lower than the value of intrahepatic and common bile duct cancers (83.3% vs 91.3%, 90.9%); moreover, in cases of perihilar cancer, the sensitivity of (18)FDG-PET was lower than that of CT scans (83.3% vs 91.7%). (18)FDG-PET detected nine distant metastatic lesions not found by other imaging studies and excluded two patients who potentially had resectable condition in other imaging studies from unnecessary laparotomy.

CONCLUSION

The clinical usefulness of (18)FDG-PET in differential diagnosis of bile duct cancers is related to the site of primary disease. Although it is a helpful method for differential diagnosis especially in cases of intrahepatic and common bile duct cancers, (18)FDG-PET can not provide confirmative clues in perihilar cholangiocarcinoma. (18)FDG-PET may hold promise in the detection of hidden distant metastasis and can play an additional role in the evaluation of resectability. (18)FDG-PET can be complementary to CT scan in diagnosing and staging of cholangiocarcinoma.

Primary Cancer of the Liver and Biliary Duct

F-18-FDG PET and PET/CT are useful for staging, predicting the prognosis, and evaluating recurrence and treatment response in hepatocellular carcinomas (HCCs) and cholangiocarcinomas. Increased F-18-FDG uptake within tumors could be a surrogate marker of aggressive behavior and poor clinical outcome, despite high false-negative rates in detecting primary intrahepatic low-grade HCCs and periductal-infiltrating cholangiocarcinomas. Dualtracer PET or PET/CT using carbon-11-acetate and F-18-FDG will increase diagnostic performance in HCC.

Predictive and prognostic value of FDG-PET

The predictive and prognostic value of fluorodeoxyglucose (FDG)-positron emission tomography (PET) in non-small-cell lung carcinoma, colorectal carcinoma and lymphoma is discussed. The degree of FDG uptake is of prognostic value at initial presentation, after induction treatment prior to resection and in the case of relapse of non-small cell lung cancer (NSCLC). In locally advanced and advanced stages of NSCLC, FDG-PET has been shown to be predictive for clinical outcome at an early stage of treatment. In colorectal carcinoma, limited studies are available on the prognostic value of FDG-PET, however, the technique appears to have great potential in monitoring the success of local ablative therapies soon after intervention and in the prediction and evaluation of response to radiotherapy, systemic therapy, and combinations thereof. The prognostic value of end-of treatment FDG-PET for FDG-avid lymphomas has been established, and the next step is to define how to use this information to optimize patient outcome. In Hodgkin's lymphoma, FDG-PET has a high negative predictive value, however, histological confirmation of positive findings should be sought where possible. For non-Hodgkin's lymphoma, the opposite applies. The newly published standardized guidelines for interpretation formulates specific criteria for visual interpretation and for defining PET positivity in the liver, spleen, lung, bone marrow and small residual lesions. The introduction of these guidelines should reduce variability among studies. Interim PET offers a reliable method for early prediction of long-term remission, however it should only be performed in prospective randomized controlled trials. Many of the diagnostic and management questions considered in this review are relevant to other tumour types. Further research in this field is of great importance, since it may lead to a change in the therapeutic concept of cancer. The preliminary findings call for systematic inclusion of FDG-PET in therapeutic trials to adequately position FDG-PET in treatment time lines.

Positron emission tomography/computer tomography: Challenge to conventional imaging modalities in evaluating primary and metastatic liver malignancies

Computer tomography (CT) and magnetic resonance imaging (MRI), as conventional imaging modalities, are the preferred methodology for tumor, nodal and systemic metastasis (TNM) staging. However, all the noninvasive techniques in current use are not sufficiently able to identify primary tumors and even unable to define the extent of metastatic spread. In addition, relying exclusively on macromorphological characteristics to make a conclusion runs the risk of misdiagnosis due mainly to the intrinsic limitations of the imaging modalities themselves. Solely based on the macromorphological characteristics of cancer, one cannot give an appropriate assessment of the biological characteristics of tumors. Currently, positron emission tomography/computer tomography (PET/CT) are more and more widely available and their application with ¹⁸F-fluorodeoxyglucose (¹⁸F-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 ¹⁸F-FDG, PET and PET/CT in order to establish diagnosis of tumors, assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. PET/CT with ¹⁸F-FDG as a radiotracer 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 hepatic metastases, hepatocellular carcinoma and cholangiocarcinoma.

Fluorine-18 fluorodeoxyglucose positron emission tomography predicts tumor differentiation, P-glycoprotein expression, and outcome after resection in hepatocellular carcinoma

PURPOSE

To investigate the diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for prediction of tumor differentiation, P-glycoprotein (P-gp) expression, and outcome in hepatocellular carcinoma (HCC) patients.

EXPERIMENTAL DESIGN

Seventy HCC patients who underwent curative resection were prospectively enrolled in the study. FDG-PET was done 2 weeks preoperatively, and the standardized uptake value (SUV) and the tumor to nontumor SUV ratio (TNR) were calculated from FDG uptake. Tumor differentiation and P-gp expression were examined with H&E and immunohistochemical staining, respectively.

RESULTS

SUV and TNR were significantly higher in poorly differentiated HCCs than in well-differentiated (P = 0.001 and 0.002) and moderately differentiated HCCs (P < 0.0001 and P < 0.0001). The percentage P-gp-positive area was significantly higher in well-differentiated HCCs than in poorly differentiated (P < 0.0001) and moderately differentiated HCCs (P = 0.0001). Inverse correlations were found between SUV and P-gp expression (r = -0.44; P < 0.0001) and between TNR and P-gp expression (r = -0.47; P = 0.01). Forty-three (61.4%) patients had postoperative recurrence. The overall and disease-free survival rates in the high TNR (> or =2.0) group were significantly lower than in the low TNR (<2.0) group (P = 0.0001 and 0.0002). In multivariate analysis, a high alpha-fetoprotein level (risk ratio, 5.46; P = 0.003; risk ratio, 8.78; P = 0.006) and high TNR (risk ratio, 1.3; P = 0.03; risk ratio, 1.6; P = 0.02) were independent predictors of postoperative recurrence and overall survival.

CONCLUSIONS

The results suggest that preoperative FDG-PET reflects tumor differentiation and P-gp expression and may be a good predictor of outcome in HCC.

Preoperative positron emission tomography with fluorine-18-fluorodeoxyglucose is predictive of prognosis in patients with hepatocellular carcinoma after resection

BACKGROUND

Hepatocellular carcinomas (HCCs) accumulate fluorine-18 fluorodeoxyglucose (FDG) to various degrees. The standardized uptake values (SUVs) of FDG-positron emission tomography (PET) in high-grade HCCs are significantly higher than those in low-grade HCCs.

AIM

The aim of this study was to evaluate the possible usefulness of FDG-PET in predicting the prognosis of HCC patients after resection. We analyzed the relationship between the tumor to non-tumor SUV ratios (SUV ratio) and surgical outcome in 31 patients.

RESULTS

Of the 31 cases of HCC studied, seven (23%) exhibited SUV ratios greater than 2, as the cutoff value. The percentage of patients with poorly differentiated HCC was greater in the higher SUV ratio group (SUV ratio >2) than in the lower SUV ratio group (SUV ratio <2) (57 vs. 32%). The overall survival was significantly longer in the lower SUV ratio group than in the higher SUV ratio group (5-year-survival rate: 63 vs. 29% P = 0.006) (median survival time: 2310 vs.182 days).

CONCLUSION

The SUV ratio was related significantly to disease-related death as well as other predictive factors, including the number of tumors, the size, stage, and involvement of vessels, and the involvement of the capsule. Consequently, we conclude that the SUV ratio provides information of prognostic relevance in patients with HCC before surgery.

FDG-PET for prediction of survival of patients with metastatic colorectal carcinoma

BACKGROUND

The current study focuses on the prognostic value of pretreatment metabolic activity in metastases as measured with [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET), as an indicator of survival in colorectal cancer.

PATIENTS AND METHODS

In a prospective series of 152 patients with metastatic colorectal cancer, of whom 67 were treated with resection of metastases and 85 with chemotherapy, standardized uptake values (SUV) as measured with FDG-PET, were calculated prior to treatment. Survival probabilities were estimated by Cox proportional regression analysis. For Kaplan-Meier analysis SUV was stratified by the median value. Survival differences were assessed using the log-rank test.

RESULTS

SUV in metastases was a significant predictor for overall survival (hazard ratio 1.17, 95% confidence interval 1.06-1.30, P = 0.002), independent of the subsequent treatment. According to the median value of the patient population a low (SUV <4.26) and high uptake group (SUV >4.26) was defined. The median survival and the 2- and 3-year survival rates were 32 months, 59% and 45%, respectively, in the low-uptake group and 19 months, 37% and 28%, respectively, in the high-uptake group (P = 0.017).

CONCLUSION

A significant survival benefit was observed in patients with low FDG uptake in metastases of colorectal cancer.

Gastrointestinal malignancies evaluated with (18)F-fluoro-2-deoxyglucose positron emission tomography

(18)F-fluoro-2-deoxyglucose positron emission tomography has demonstrated high accuracy in the staging and evaluation of colorectal and esophageal carcinomas. FDG PET is demonstrating increasing utility in a number of other gastrointestinal tumours and clinical scenarios. The established clinical indications for its use, the diagnostic accuracy, and limitations will be reviewed. Data on the emerging indications and limitations for pancreatic, hepatocellular, and gastric carcinomas, as well as gastrointestinal stromal tumours, cholangiocarcinoma, and carcinoma of unknown primary will also be briefly discussed. The use of combined PET-CT is demonstrating further improvements in diagnostic accuracy.

Applications of PET in Liver Imaging

Fluorodeoxyglucose PET (FDG-PET) imaging has an important role in determining if there are metastases to the liver and whether disease has spread beyond the liver. Such information is critical for planning surgical resections of liver metastases. The ability of FDG-PET quantitatively to estimate metabolic rates makes it an important tool for monitoring. With increasingly broad indications for FDG-PET imaging, it is expected that FDG-PET (and PET-CT) of the liver will play a growing and increasingly important role in detecting and monitoring treatment of tumors involving the liver.

Hepatocellular carcinoma: current surgical management

Hepatocellular carcinoma (HCC) is the fifth most common malignancy in the world, responsible for 500,000 deaths globally every year. Although HCC is a slow-growing tumor, it is often rapidly fatal because it is usually not discovered until the disease is advanced. HCC occurs primarily in individuals with cirrhosis, a condition that increases the risk of performing potentially curative surgical therapy. Over the last 2 decades, however, the safety of surgical resections has greatly improved because of advances in radiologic assessment, patient selection, and perioperative care. As such, the operative mortality rate for hepatectomy has decreased from the 10%-20% level seen in the 1980s to less than 5% today. The ultimate goal of treatment of HCC is to prolong the quality of life by eradicating the malignancy while preserving hepatic function. For treatment with a curative intent, the gold standard remains surgical resection, by either partial hepatectomy or total hepatectomy followed by liver transplantation. Resectability and choice of procedure depend on many factors, including baseline liver function, absence of extrahepatic metastases, size of residual liver, availability of resources including liver graft, and expertise of the surgical team. Patients without cirrhosis can tolerate extensive resections, and partial hepatectomy should be considered first. For Child class B and C patients with a small HCC, liver transplantation offers the best results, whereas partial liver resection is indicated in patients with well-compensated cirrhosis. Living donor liver transplantation should be considered using the same criteria as that used for cadaveric transplantation.

PET imaging in assessing gastrointestinal tumors

The clinical usefulness of FDG-PET imaging is now firmly established in various situations, such as the preoperative staging of esophageal cancer and recurrent colorectal carcinoma and the detection and staging of recurrent colorectal cancer when there is a clinical or biologic suspicion with inconclusive conventional findings. Encouraging results were obtained in the evaluation of the therapeutic response of various gastrointestinal malignancies, either during the treatment or after its completion. There is no firm consensus regarding its role in pancreatic cancer, either proved or suspected, but it may be valuable in selected clinical situations. Its role seems fairly limited in patients with hepatocellular carcinoma, although PET findings may have prognostic implications. Evaluation of cholangiocarcinoma is an emerging indication, albeit with limited data to date. Finally, PET/CT is very likely to enhance the role of FDG imaging further in the work-up of patients with gastrointestinal tumors.

Molecular imaging of hepatocellular carcinoma

Molecular imaging may be defined as spatially localized and/or temporally resolved sensing of molecular and cellular processes in vivo. An imageable molecular event may be the result of the overexpression of a gene that produces a specific messenger RNA. The overexpressed protein could be an enzyme or could be incorporated into cell-surface transporters or receptors. Any step of this process is a potential target for molecular imaging. Current molecular imaging modalities include magnetic resonance imaging, nuclear imaging, ultrasound, and optical imaging. Nuclear medicine has been at the forefront of molecular imaging because of the relatively high sensitivity to detect nanomolar or picomolar quantities of the radiolabeled imaging probe. Imaging has had a central role in the diagnosis of hepatocellular carcinoma (HCC), which is considered the fifth most frequent malignancy worldwide. Nuclear imaging was one of the earlier modalities used for liver imaging. Traditional tracers included technetium 99m ( 99m Tc) sulfur colloid, gallium 67, and 99m Tc iminodiacetate acid analogues. Other less traditional probes include 99m Tc diethylenetriamine pentaacetic acid-galactosyl-human serum albumin for evaluation of functional liver volume and 99m Tc-labeled tetrofosmin and methoxisobutylisonitrile for detecting drug resistance. Fluorodeoxyglucose is the most widely used probe for positron emission tomography (PET) tumor imaging; however, carbon 11-labeled acetate appears to show improved sensitivity and specificity for HCC. Oxygen 15 PET imaging allows for the measurement of hepatic and tumor blood flow. Difficulties developing specific imaging methods for HCC are caused by the lack of obvious specific molecular targets, problems with drug delivery, and poor contrast-to-noise. No magic molecular imaging method exists today to accurately detect, characterize, and monitor HCC in vivo.

Recent advances in imaging hepatocellular carcinoma: diagnosis, staging and response assessment: functional imaging

Historically, nuclear medicine has had an important role in the differential diagnosis of liver tumors but has been largely superseded by other forms of conventional imaging, in particular computed tomographic portography. It remains helpful in difficult cases because it has characteristic features in both hepatocellular carcinoma (HCC) and benign conditions. 131I is an important therapeutic tool. FDG-PET is useful in certain cases, especially for finding metastases and monitoring response to therapy.

Analysis of gene expression profiles of hepatocellular carcinomas with regard to 18F-fluorodeoxyglucose uptake pattern on positron emission tomography

PURPOSE

18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) scan has been found to reflect tumour aggressiveness and prognosis in various types of cancer. In this study, the gene expression profiles of hepatocellular carcinomas (HCCs) were evaluated to determine whether HCCs with high 18F-FDG uptake have more aggressive biological potential than those with low uptake.

METHODS

Surgical specimens were obtained from ten patients with HCC (six males and four females, age range 38-68 years). The tumour samples were divided into two groups based on the 18F-FDG PET scan findings: high 18F-FDG uptake (n=4) and low 18F-FDG uptake (n=6).

RESULTS

The pathological tumour grade was closely correlated with the 18F-FDG uptake pattern: HCCs with high 18F-FDG uptake were pathologically Edmondson-Steiner grade III, while those with low uptake were either grade II or grade II with a focal area of grade III. The total RNA was extracted from the frozen tissues of all HCCs (n=10) and adjacent non-cancerous tissue (n=7). The gene expression profiles were evaluated using an oligoDNA microarray. The HCCs with high 18F-FDG uptake showed increased expression of 11 genes--including vascular cell adhesion molecule-1, vinexin beta and core 1 UDP-galactose:N-acetylgalactosamine-alpha-R-beta 1,3-galactosyltransferase and the natural killer cell inhibitory receptor--compared to those with low uptake (p<0.005). Nine genes, including regulator of mitotic spindle assembly 1, grb2-related adaptor protein and beta-1,3-n-acetylglucosaminyltransferase, were repressed.

CONCLUSION

Gene expression is closely related to cell survival, cell-to-cell adhesion or cell spreading; therefore, HCCs with high 18F-FDG uptake appear to have more aggressive biological properties than those with low uptake.

Surgical management of hepatic malignancy

Over the past twenty-five years, hepatic resection has evolved from a high risk, resource-intensive procedure with limited application to a safe and commonly performed operation with broad indications. This period has seen dramatic improvements in perioperative outcome, including reductions in mortality, blood loss, transfusion rates, and hospital stay. These improved perioperative results are largely responsible for the emergence of hepatic resection as a viable and effective treatment option for selected patients with 1 degree and 2 degrees hepatobiliary malignancy. Continued advances in imaging technology, along with a heightened awareness of the clinical and tumor-related variables that dictate outcome, have allowed better preoperative assessment of disease extent and improved patient selection. Advances in other areas, such as minimally invasive and ablative techniques, have increased the treatment options and have had some impact on the approach to patients with malignant hepatobiliary disease; however, resection remains the most effective therapy. Although the long term results after resection are better than with other modalities, recurrence rates remain high, and further improvements in survival will require more effective systemic agents. As better adjuvant and neo-adjuvant therapies emerge, the results of resection are likely to improve and the indications for its application perhaps will extend to patients currently considered to have unresectable disease.

Feasibility of optimizing the dose distribution in lung tumors using fluorine-18-fluorodeoxyglucose positron emission tomography and single photon emission computed tomography guided dose prescriptions

The information provided by functional images may be used to guide radiotherapy planning by identifying regions that require higher radiation dose. In this work we investigate the dosimetric feasibility of delivering dose to lung tumors in proportion to the fluorine-18-fluorodeoxyglucose activity distribution from positron emission tomography (FDG-PET). The rationale for delivering dose in proportion to the tumor FDG-PET activity distribution is based on studies showing that FDG uptake is correlated to tumor cell proliferation rate, which is shown to imply that this dose delivery strategy is theoretically capable of providing the same duration of local control at all voxels in tumor. Target dose delivery was constrained by single photon emission computed tomography (SPECT) maps of normal lung perfusion, which restricted irradiation of highly perfused lung and imposed dose-function constraints. Dose-volume constraints were imposed on all other critical structures. All dose-volume/function constraints were considered to be soft, i.e., critical structure doses corresponding to volume/function constraint levels were minimized while satisfying the target prescription, thus permitting critical structure doses to minimally exceed dose constraint levels. An intensity modulation optimization methodology was developed to deliver this radiation, and applied to two lung cancer patients. Dosimetric feasibility was assessed by comparing spatially normalized dose-volume histograms from the nonuniform dose prescription (FDG-PET proportional) to those from a uniform dose prescription with equivalent tumor integral dose. In both patients, the optimization was capable of delivering the nonuniform target prescription with the same ease as the uniform target prescription, despite SPECT restrictions that effectively diverted dose from high to low perfused normal lung. In one patient, both prescriptions incurred similar critical structure dosages, below dose-volume/function limits. However, in the other patient, critical structure dosage from the nonuniform dose prescription exceeded dose-volume/function limits, and greatly exceeded that from the uniform dose prescription. Strict compliance to dose-volume/ function limits would entail reducing dose proportionality to the FDG-PET activity distribution, thereby theoretically reducing the duration of local control. Thus, even though it appears feasible to tailor lung tumor dose to the FDG-PET activity distribution, despite SPECT restrictions, strict adherence to dose-volume/function limits could compromise the effectiveness of functional image guided radiotherapy.

Incorporation of functional imaging data in the evaluation of dose distributions using the generalized concept of equivalent uniform dose

Advances in the fields of IMRT and functional imaging have greatly increased the prospect of escalating the dose to highly active or hypoxic tumour sub-volumes and steering the dose away from highly functional critical structure regions. However, current clinical treatment planning and evaluation tools assume homogeneous activity/function status in the tumour/critical structures. A method was developed to incorporate tumour/critical structure heterogeneous functionality in the generalized concept of equivalent uniform dose (EUD). The tumour and critical structures functional EUD (FEUD) values were calculated from the dose-function histogram (DFH), which relates dose to the fraction of total function value at that dose. The DFH incorporates flouro-deoxyglucose positron emission tomography (FDG-PET) functional data for tumour, which describes the distribution of metabolically active tumour clonogens, and single photon emission computed tomography (SPECT) perfusion data for critical structures. To demonstrate the utility of the method, the lung dose distributions of two non-small cell lung cancer patients, who received 3D conformal external beam radiotherapy treatment with curative intent, were evaluated. Differences between the calculated lungs EUD and FEUD values of up to 50% were observed in the 3D conformal plans. In addition, a non-small cell lung cancer patient was inversely planned with a target dose prescription of 76 Gy. Two IMRT plans (plan-A and plan-B) were generated for the patient based on the CT, FDG-PET and SPECT treatment planning images using dose-volume objective functions. The IMRT plans were generated with the goal of achieving more critical structures sparing in plan-B than plan-A. Results show the target volume EUD in plan-B is lower than plan-A by 5% with a value of 73.31 Gy, and the FEUD in plan-B is lower than plan-A by 2.6% with a value of 75.77 Gy. The FEUD plan-B values for heart and lungs were lower than plan-A by 22% and 18%, respectively. While EUD values show plan-A is marginally better than plan-B in terms of target volumetric coverage, the FEUD plan-B values show adequate target function coverage with significant critical structure function sparing. In conclusion, incorporating functional data in the calculation of EUD is important in evaluating the biological merit of treatment plans.

The role of positron emission tomography in gastrointestinal imaging

Although the use of PET in studies of the gastrointestinal tract is still relatively new, its value is clear. The future will provide a better definition of the indications for PET, refinement of the technology, and its relative value compared with other modalities such as peptide and antibody imaging, CT, MR imaging, and US.