Value of PET/CT in the management of primary hepatobiliary tumors, part 2. AJR Am J Roentgenol. 2011;197:W260-W265. [PMID: 21785051 DOI: 10.2214/ajr.11.6995]

Positron emission tomography diagnostic imaging in multidrug-resistant hepatocellular carcinoma: focus on 2-deoxy-2-(18F)Fluoro-D-Glucose

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide. Surgical resection and liver transplantation are still the best options for treatment. Nevertheless, as the number of patients who may benefit from these therapies is limited, alternative therapies have been developed, including chemotherapy. However, partly due to the expression of multidrug resistance (MDR) proteins, it has been found that HCC is a highly chemoresistant tumor. The major family of MDR proteins is the ATP-binding cassette (ABC) transporter superfamily, which includes P-glycoprotein (Pgp) and MDR-associated protein 1 (MRP1). Positron emission tomography using the radiolabeled analog of glucose, 2-deoxy-2-((18)F)fluoro-D-glucose ([(18)F]FDG), has been used in diagnostic imaging of various types of tumors. Clinical studies are inconsistent but experimental studies have shown that [(18)F]FDG uptake is associated with tumor grade and is inversely proportional to Pgp expression in HCC. These studies unveil that [(18)F]FDG can be a substrate of Pgp, although that relationship remains unclear. This review sums up the relationship between MDR expression in HCC, and [(18)F]FDG uptake by tumor cells, showing that this radiopharmaceutical may provide a useful tool for the study of chemoresistance in HCC, and that the use of this marker may contribute to the therapeutic choice on this highly aggressive tumor.

FDG PET/CT in Pancreatic and Hepatobiliary Carcinomas: Value to Patient Management and Patient Outcomes

Fludeoxyglucose F 18 ((18)F-FDG) PET/CT has not been shown to offer additional benefit in the initial diagnosis of pancreatic cancer, but studies show benefit of (18)F-FDG PET/CT in initial staging and patient prognosis. There is evidence for (18)F-FDG PET and (18)F-FDG PET/CT in staging and prognosis of cholangiocarcinoma and gallbladder cancer. (18)F-FDG PET/CT has shown promise in staging liver malignancies by detecting extrahepatic metastasis. There is evidence supporting the ability of PET/CT in predicting prognosis in patients with hepatocellular carcinoma. Evidence is evolving for the role of (18)F-FDGPET/CT in predicting prognosis and survival in patients with colorectal liver metastasis.

Kinetic analysis of dynamic (11)C-acetate PET/CT imaging as a potential method for differentiation of hepatocellular carcinoma and benign liver lesions

Objective: The kinetic analysis of ¹¹C-acetate PET provides more information than routine one time-point static imaging. This study aims to investigate the potential of dynamic ¹¹C-acetate hepatic PET imaging to improve the diagnosis of hepatocellular carcinoma (HCC) and benign liver lesions by using compartmental kinetic modeling and discriminant analysis.

Methods: Twenty-two patients were enrolled in this study, 6 cases were with well-differentiated HCCs, 7 with poorly-differentiated HCCs and 9 with benign pathologies. Following the CT scan, all patients underwent ¹¹C-acetate dynamic PET imaging. A three-compartment irreversible dual-input model was applied to the lesion time activity curves (TACs) to estimate the kinetic rate constants K₁-k₃, vascular fraction (VB) and the coefficient α representing the relative hepatic artery (HA) contribution to the hepatic blood supply on lesions and non-lesion liver tissue. The parameter Ki (=K₁×k₃/(k₂ + k₃)) was calculated to evaluate the local hepatic metabolic rate of acetate (LHMAct). The lesions were further classified by discriminant analysis with all the above parameters.

Results: K₁ and lesion to non-lesion standardized uptake value (SUV) ratio (T/L) were found to be the parameters best characterizing the differences among well-differentiated HCC, poorly-differentiated HCC and benign lesions in stepwise discriminant analysis. With discriminant functions consisting of these two parameters, the accuracy of lesion prediction was 87.5% for well-differentiated HCC, 50% for poorly-differentiated HCC and 66.7% for benign lesions. The classification was much better than that with SUV and T/L, where the corresponding classification accuracy of the three kinds of lesions was 57.1%, 33.3% and 44.4%.

Conclusion: ¹¹C-acetate kinetic parameter K₁ could improve the identification of HCC from benign lesions in combination with T/L in discriminant analysis. The discriminant analysis using static and kinetic parameters appears to be a very helpful method for clinical liver masses diagnosis and staging.

Liver standardized uptake value corrected for lean body mass at FDG PET/CT: effect of FDG uptake time

OBJECTIVE

The objective of this study is to establish the magnitude change and interreader reliability of the liver standardized uptake value corrected for lean body mass (SULmean) in dual-time-point imaging at 1 and 2 hours and 1 and 4 hours.

PATIENTS AND METHODS

Early and delayed FDG PET/CT scans were included for 28 patients (13 men and 15 women) who had normal liver by CT or ultrasound. The average uptake time between the early and delayed scans were 55 minutes (range, 44-69 minutes) for pancreatic adenocarcinoma patients (n = 19) and 184 minutes (range, 140-197 minutes) for neurofibromatosis patients (n = 9). A 30-mm-diameter spherical volume of interest was placed within the right lobe of the liver above, below, and at the level of the main portal vein by 2 independent readers. Correlation coefficients, analysis of variance, intraclass correlation coefficient, and Bland-Altman analysis were performed.

RESULTS

The mean liver SULmean was between 1.39 and 1.42 and between 1.28 and 1.3 in early and delayed images, respectively (P = 0.001). There is time-dependent reduction in the mean liver SULmean at 2-hour (7%-8%) and 4-hour uptake time (15%-21%) compared with 1-hour uptake time. The correlation coefficient between delayed uptake time and liver SULmean reduction is 0.39 to 0.41 at the upper aspect of the liver. The intraclass correlation coefficient for 2 readers varied between 0.997 and 0.998 and between 0.995 and 0.999 in early and delayed images, respectively (P = 0.001).

CONCLUSIONS

There is time-dependent reduction of mean liver SULmean, about 7% to 8% within the clinically relevant FDG uptake time, in the same patient with excellent interreader agreement in early and delayed images within the right lobe of the liver. Therefore, liver SULmean could represent a useful reference parameter in quantitative analysis of dual-phase FDG PET/CT in malignancy or atypical infection/inflammatory disease. Furthermore, it may be suitable as a normalization factor in currently available formulae quantifying therapy response on PET imaging.

FDG volumetric parameters and survival outcomes after definitive chemoradiotherapy in patients with recurrent head and neck squamous cell carcinoma

OBJECTIVE

The purpose of this study was to establish the predictive value of (18)F-FDG parameters for overall survival in biopsy-proven recurrent head and neck squamous cell cancer (HNSCC) patients after definitive chemoradiotherapy.

MATERIALS AND METHODS

We conducted a retrospective study including 34 patients with HNSCC who had biopsy-proven recurrence between April 2004 and March 2012 and underwent FDG PET/CT at our institution at the time of recurrence. Maximum standardized uptake value (SUVmax), peak SUV (SUVpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured. The primary outcome measure was overall survival. ROC analysis, univariate and multivariate Cox regression models, and Kaplan-Meir survival curves were performed.

RESULTS

In univariate analyses, human papillomavirus (HPV) status (p = 0.04), primary site recurrence of MTV (p = 0.03), metastasis of MTV (p = 0.02), metastasis of TLG (p = 0.02), total MTV (p = 0.002), and total TLG (p = 0.04) were significantly associated with overall survival outcome. Total MTV remained as significant independent prognostic factor when adjusted for all other covariates except for primary site recurrence SUVmax and SUVpeak and lymph node SUVmax and SUVpeak. There was a significant difference in time to survival between patients with total MTV above and below the 50th percentile (Mantel-Cox log-rank test, p = 0.05 and Gehan-Breslow-Wilcoxon test, p = 0.03) and the optimum threshold of 16.8 mL (Mantel-Cox log-rank test, p = 0.01 and Gehan-Breslow-Wilcoxon test, p = 0.01; hazard ratio [HR], 0.25).

CONCLUSION

FDG PET/CT-based total MTV and clinical HPV status may be significant prognostic markers for overall survival of patients with recurrent HNSCC after definitive chemoradiotherapy.

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.

PET/CT in the management of thyroid cancers

OBJECTIVE

Thyroid cancer is the most common endocrine cancer. This review evaluates the established use of (18)F-FDG PET/CT in papillary, follicular, Hürthle cell, anaplastic, and medullary thyroid cancers. The significance of incidental diffuse and focal thyroid FDG uptake is discussed. The evolving value of non-FDG radiotracers, including (124)I, (18)F-dihydroxyphenylalanine, and (68)Ga somatostatin analogs, is summarized.

CONCLUSION

PET/CT is a valuable imaging test, in the appropriate clinical context, for the management of thyroid cancers.

Hepatocellular adenoma showing high uptake of (18)F-fluorodeoxyglucose (FDG) via an increased expression of glucose transporter 2 (GLUT-2)

Hepatocellular adenoma (HCA) is a benign liver neoplasm composed of hepatocytes. We experienced HCA demonstrating a high uptake of (18)F-fluorodeoxyglucose (FDG) on positron emission tomography-computed tomography, mimicking a malignant tumor. The mechanism underlying the uptake of FDG has not been identified. Here, we discuss that an enhancement of glucose metabolism via an increased expression of glucose transporter 2 may have a role in the high uptake of FDG shown by HCAs.

Imaging features following transarterial chemoembolization and radiofrequency ablation of hepatocellular carcinoma

Transarterial chemoembolization and radiofrequency ablation are currently the most widely used modalities in the minimally invasive treatment of unresectable hepatocellular carcinoma. This article briefly summarizes the minimally invasive therapeutic options in the management of hepatocellular carcinoma focusing on transarterial chemoembolization and radiofrequency ablation and describes normal post-treatment imaging appearances. Imaging features of post-treatment local tumor recurrence as well as procedure-related complications following these interventions have also been described.

Prognostic Value of SUVmax Measured by Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography in Patients with Gallbladder Cancer

OBJECTIVE

The aim of this study is to investigate the prognostic value of F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET)/computed tomography (CT) in gallbladder cancer patients.

METHODS

From June 2004 to June 2010, a total of 50 patients with gallbladder cancer who underwent diagnostic staging with F-18 FDG PET/CT following curative or palliative treatments were retrospectively evaluated. For the analysis, all patients were classified by age, sex, maximum standardized uptake value (SUVmax), lymph node (LN) or distant metastasis, serum level of CA19-9 and CEA, type of treatment and American Joint Committee on Cancer (AJCC) stage.

RESULTS

The median survival for the 50 patients was 245 days and the median SUVmax in PET/CT was 8.3 (range, 0-19.7). Patients with SUVmax < 6 survived significantly longer than patients with SUVmax ≥ 6 (median 405 days vs 203 days, p = 0.0400). On Kaplan-Meier analysis, SUVmax (p = 0.0400), stage (p = 0.0001), CA19-9 (p = 0.013), CEA (p = 0.006), LN metastasis (p = 0.0001), distant metastasis (p = 0.0020), type of treatment (p = 0.0001) were significantly associated with overall survival. Multivariate analysis study revealed that the patients with lower SUVmax measured from initial staging PET/CT (p = 0.0380), no LN metastasis (p = 0.0260), a lower stage (p = 0.026) and curative treatment (p = 0.0005) had longer survivals.

CONCLUSIONS

The present study shows that SUVmax on F-18 FDG PET/CT can provide prognostic information in patients with gallbladder cancer.

Modern perspectives on factors predisposing to the development of gallbladder cancer

BACKGROUND

Gallbladder cancer (GBC) is a rare malignancy, yet certain groups are at higher risk. Knowledge of predisposing factors may facilitate earlier diagnosis by enabling targeted investigations into otherwise non-specific presenting signs and symptoms. Detecting GBC in its initial stages offers patients their best chance of cure.

METHODS

PubMed was searched for recent articles (2008-2012) on the topic of risk factors for GBC. Of 1490 initial entries, 32 manuscripts reporting on risk factors for GBC were included in this review.

RESULTS

New molecular perspectives on cholesterol cycling, hormonal factors and bacterial infection provide fresh insights into the established risk factors of gallstones, female gender and geographic locality. The significance of polyps in predisposing to GBC is probably overstated given the known dysplasia-carcinoma and adenoma-carcinoma sequences active in this disease. Bacteria such as Salmonella species may contribute to regional variations in disease prevalence and might represent powerful targets of therapy to reduce incidences in high-risk areas. Traditional risk factors such as porcelain gallbladder, Mirizzi's syndrome and bile reflux remain important as predisposing factors.

CONCLUSIONS

Subcentimetre gallbladder polyps rarely become cancerous. Because gallbladder wall thickening is often the first sign of malignancy, all gallbladder imaging should be scrutinized carefully for this feature.

The role of PET/CT in the management of cervical cancer

OBJECTIVE. Cervical cancer is the second most common malignancy in women worldwide and the third most common cause of cancer mortality in the United States. The aim of this article is to describe cervical cancer and outline the value of (18)F-FDG PET/CT in the management of cervical malignancy. CONCLUSION. The value of PET/CT has been found in staging and treatment strategy for cervical cancer. FDG PET/CT facilitates decision-making and radiation treatment planning and provides important information about treatment response, disease recurrence, and long-term survival.

Role of positron emission tomography-computed tomography in gastrointestinal malignancies

Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.