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]

PET imaging of hepatocellular carcinoma with [124I]IV-14

BACKGROUND

Currently, positron emission tomography (PET) plays no clear role in clinical imaging and management of hepatocellular carcinoma (HCC). New radiotracers for new target(s) are needed for PET imaging of HCC. Uridine-cytidine kinase 2 (UCK2) is a rate-limiting enzyme of the pyrimidine salvage synthesis pathway to phosphorylate uridine and cytidine. Studies have demonstrated that UCK2 is overexpressed in many types of solid cancers including HCC and is associated with the poor prognosis and proliferation of HCC. This study reported PET imaging using a UCK2-specific radiotracer with a clinically relevant anima model of spontaneously occurring HCC in the woodchucks.

METHODS

This study used 3'-(E)-(2-iodovinyl) uridine (IV-14), which is derived from a UCK2-selective antitumor agent 3'-(Ethynyl)uridine (EUrd), a cytotoxic ribonucleoside analogs of uridine. By radiolabeling IV-14 with Iodine-124 (124I), a UCK2-specific radiotracer [124I]IV-14 was obtained for PET imaging of UCK2. A naturally occurring woodchuck model of HCC following chronic viral hepatitis infection was used for PET imaging. Potassium iodide (KI) was tested in one of the three animals to block possible uptake of free 124I from de-iodination of [124I]IV-14.

RESULTS

We confirmed that UCK2 expression is higher in the woodchuck model of HCC than in the surrounding hepatic tissue, similar to human UCK2 that is highly expressed in human HCC. PET imaging with [124I]IV-14 showed a strong uptake in woodchuck HCC with low background uptake at one-hour post-injection. De-iodination did not seem to be an issue for PET imaging.

CONCLUSION

Our results demonstrate that UCK2 is a viable target for imaging HCC and has the potential for targeted endoradiotherapy of HCC.

Monitoring Sorafenib Resistance and Efficacy in Hepatocellular Carcinoma Using [18F]Alfatide II and [18F]Fluorodeoxyglucose Positron Emission Tomography

Integrin αvβ3 expression is associated with sorafenib resistance in hepatocellular carcinoma (HCC). Therefore, monitoring its expression in HCC may serve as a valuable indicator of the efficacy of sorafenib treatment. In this study, longitudinal positron emission tomography (PET) was performed to assess [18F]Alfatide II and [18F]fluorodeoxyglucose ([18F]FDG) as suitable probes for evaluating the treatment efficacy of sorafenib in a Huh-7 human (HCC) xenograft model. Huh-7 tumor cells were used to establish both normal and sorafenib-resistant cell lines, and xenograft models were developed. The mice were categorized into four groups based on the cell type and treatment: normal nontreatment, normal treatment, sorafenib-resistant nontreatment, and sorafenib-resistant treatment. Huh-7 tumor mice received intragastric injections of sorafenib (30 mg/kg/day) or vehicle for 15 consecutive days. Tumor size and weight were assessed throughout the study. Longitudinal microPET/computed tomography (CT) scans with [18F]Alfatide II and [18F]FDG were acquired to quantitatively measure angiogenesis on days -2, 3, 7, and 14 and metabolism on days -1, 4, 8, and 15 following therapy initiation. The tumor uptake (ID%/gmean) of each probe was calculated. No significant difference in [18F]FDG uptake was observed between the normal and sorafenib-resistant groups (P = 0.452); however, [18F]Alfatide II uptake differed significantly between the two groups (P < 0.001). Sorafenib successfully inhibited normal Huh-7 tumor growth, inducing significant differences in tumor size 9 days after sorafenib treatment (P < 0.05). The uptake of [18F]Alfatide II in the tumor lesions changed significantly on day 14 (P = 0.001). However, no change was observed in the uptake of [18F]FDG (P > 0.05). The PET imaging data of [18F]Alfatide II and [18F]FDG were validated through ex vivo immunohistochemistry analysis targeting integrin αvβ3, VEGF, and GULT-1. [18F]Alfatide II PET was more effective in monitoring sorafenib resistance and therapeutic efficacy in the Huh-7 human HCC xenograft model than [18F]FDG.

166Ho-RadioEmbolizaTiOn Using personalized prediCtive dosimetry in patients with Hepatocellular carcinoma: A prospective, single-centre study (RETOUCH)

BACKGROUND AND AIMS

Holmium-166 (166Ho) radioembolization could offer a more individualized approach in terms of imaging and dosimetry. We aim to evaluate the feasibility and safety of 166Ho selective internal radiation therapy (SIRT) using a higher tumour dose than previously administered determined by 166Ho-scout as a surrogate marker in HCC patients.

METHODS

This is an open-label, prospective, non-randomized, single-centre pilot study that included patients with HCC that received 166Ho-SIRT if the work-up using 166Ho-scout showed a tumour-absorbed dose ≥150 Gy, a non-tumoural liver absorbed dose less than 60 Gy and a lung absorbed dose less than 30 Gy. Primary endpoints were feasibility and safety-toxicity profiles at 24-48 h and 1 month. Overall response rates (ORR) at 3 months (mRECIST, RECIST 1.1 and metabolic response by FDG and choline PET CT) and time to progression (TTP) represented the secondary endpoints.

RESULTS

Fifteen patients with large tumours (mean diameter 55.67 ± 28.42 mm) received 17 166Ho-SIRT treatments between July 2020 and June 2022. All the attempted treatments were accomplished. Mean administered tumour dose was 183.18 ± 71.71 Gy, while non-tumour liver dose was 30.29 ± 14.56 Gy. Median time of follow-up was 12 months (IQR 9-16). Only grade 1-2 clinical and biological AEs were observed. There were no liver decompensations. At 3 months, objective response was achieved for all target lesions (CR 78.57%, PR 21.43% according to mRECIST). Median TTP was 18.8 (range 2.9; n.e.) months.

CONCLUSION

Personalized 166Ho-SIRT with a tumour delivered dose ≥150 Gy was feasible and safe for HCC patients with promising response rates.

PET/MRI: pictorial review of hepatobiliary and pancreatic applications

PET and MRI both play valuable roles in the management of hepatobiliary and pancreatic (HBP) malignancies. Simultaneous PET/MRI combines the excellent soft-tissue resolution and anatomic details from MRI with functional information from PET in a single comprehensive examination. MRI is the main imaging modality in evaluating HCC, playing important roles in screening, characterization, local extent, and evaluating tumor response, whereas 18F-fluorodeoxyglucose (FDG) PET can help evaluate for lymph node involvement and metastatic disease. In cholangiocarcinoma and pancreatic malignancies, both PET and MRI have excellent utility in initial staging as well as assessing treatment response. In all HBP malignancies, FDG-PET/MRI is a unique problem-solving tool in complex cases and diagnostic challenges, especially after locoregional therapy and when differentiating residual or recurrent viable disease from inflammatory and other benign processes. In this manuscript, we review the role of PET/MRI in the diagnosis, staging, assessing treatment response, and characterizing post-treatment processes. With the introduction of multiple new tracers, the value of PET/MRI has not yet been fully realized, and more studies are needed to demonstrate the utility and efficacy of PET/MRI in improving patient care in hepatobiliary and pancreatic oncology.

PET/MRI evaluation of hepatobiliary tumors

Positron-emission tomography magnetic resonance imaging (PET/MRI) has emerged as a powerful hybrid molecular imaging technique in clinical practice, overcoming initial technical challenges to provide comprehensive anatomic and metabolic information. This advanced modality combines the superior soft tissue contrast of MRI with the metabolic insights of PET, offering advantages in hepatobiliary imaging, including improved detection of small liver metastases and reduced radiation exposure. The evolution of PET/MRI technology has been marked by significant advancements, such as the development of MRI-compatible PET detectors and sophisticated motion compensation techniques. These innovations have enhanced image quality and co-registration accuracy, crucial for hepatobiliary imaging. The integration of time-of-flight capability and silicon photomultipliers has further improved spatial resolution and sensitivity. PET/MRI protocols for liver imaging typically involve a whole-body scan followed by a targeted liver examination, utilizing radiotracers like FDG and DOTATATE. This approach allows for comprehensive staging and detailed liver assessment in a single session, potentially altering management decisions in up to 30% of patients with intrahepatic cholangiocarcinoma. While PET/MRI excels in characterizing various hepatobiliary lesions, including hepatocellular carcinoma and cholangiocarcinoma, challenges remain in differentiating certain benign entities like small hemangiomas from metastases. Ongoing research and clinical experience continue to refine the role of PET/MRI in hepatobiliary imaging, promising improved diagnostic accuracy and patient care.

Unexpected focal fluorodeoxyglucose uptake in main organs; pass through or pass by?

Since the inception of fluorine-18 fluorodeoxyglucose (F-18 FDG), positron emission tomography/computed tomography (PET/CT) utilizing F-18 FDG has become widely accepted as a valuable imaging modality in the field of oncology, with global prevalence in clinical practice. Given that a single Torso PET/CT scan encompasses the anatomical region from the skull base to the upper thigh, the detection of incidental abnormal focal hypermetabolism in areas of limited clinical interest is both feasible and not uncommon. Numerous investigations have been undertaken to delineate the distinctive features of these findings, yet the outcomes have proven inconclusive. The incongruent results of these studies present a challenge for physicians, leaving them uncertain about the appropriate course of action. This article provides a succinct overview of the characteristics of fluorodeoxyglucose, followed by a comprehensive discussion of the imaging findings and clinical significance associated with incidental focal abnormal F-18 FDG activity in several representative organs. In conclusion, while the prevalence of unrecognized malignancy varies across organs, malignancies account for a substantial proportion, ranging from approximately one-third to over half, of incidental focal uptake. In light of these rates, physicians are urged to exercise vigilance in not disregarding unexpected uptake, facilitating more assured clinical decisions, and advocating for further active evaluation.

Hepatocellular Carcinoma: Optimal Radiological Evaluation before Liver Transplantation

Liver transplantation (LT) is the recommended curative-intent treatment for patients with early or intermediate-stage hepatocellular carcinoma (HCC) who are ineligible for resection. Imaging plays a central role in staging and for selecting the best LT candidates. This review will discuss recent developments in pre-LT imaging assessment, in particular LT eligibility criteria on imaging, the technical requirements and the diagnostic performance of imaging for the pre-LT diagnosis of HCC including the recent Liver Imaging Reporting and Data System (LI-RADS) criteria, the evaluation of the response to locoregional therapy, as well as the non-invasive prediction of HCC aggressiveness and its impact on the outcome of LT. We will also briefly discuss the role of nuclear medicine in the pre-LT evaluation and the emerging role of artificial intelligence models in patients with HCC.

Intraoperative Imaging in Hepatopancreatobiliary Surgery

Hepatopancreatobiliary surgery belongs to one of the most complex fields of general surgery. An intricate and vital anatomy is accompanied by difficult distinctions of tumors from fibrosis and inflammation; the identification of precise tumor margins; or small, even disappearing, lesions on currently available imaging. The routine implementation of ultrasound use shifted the possibilities in the operating room, yet more precision is necessary to achieve negative resection margins. Modalities utilizing fluorescent-compatible dyes have proven their role in hepatopancreatobiliary surgery, although this is not yet a routine practice, as there are many limitations. Modalities, such as photoacoustic imaging or 3D holograms, are emerging but are mostly limited to preclinical settings. There is a need to identify and develop an ideal contrast agent capable of differentiating between malignant and benign tissue and to report on the prognostic benefits of implemented intraoperative imaging in order to navigate clinical translation. This review focuses on existing and developing imaging modalities for intraoperative use, tailored to the needs of hepatopancreatobiliary cancers. We will also cover the application of these imaging techniques to theranostics to achieve combined diagnostic and therapeutic potential.

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.

Comparison between PSMA PET/CT and MRI for Characterizing Hepatocellular carcinoma: A Real-World Study

Prostate specific membrane antigen (PSMA) is expressed by hepatocellular carcinoma (HCC). PSMA PET/CT has potential as an imaging agent for the detection of HCC including early diagnosis and monitoring for recurrence following surgical resection. This study aims to compare PSMA PET to standard surveillance imaging in the detection of HCC. Patients with suspected or treated HCC were prospectively recruited from a tertiary hospital outpatient clinic. In addition to routine surveillance imaging as recommended by the multidisciplinary team, a PSMA PET/CT was performed. Imaging and clinical characteristics were compared over a follow-up period of up to 12 months. In a cohort of 19 patients with known HCC or suspected recurrent HCC, PSMA PET/CT had similar efficacy to MRI for the detection of HCC, with a sensitivity of 91% and a specificity of 70% and sensitivity of 87% and a specificity of 73% for PSMA PET/CT and MRI, respectively. PSMA PET/CT had a higher negative predictive value of 90%. In this relatively large single centre study, PSMA is shown to have promising equivalence in performance and its role should be further evaluated in multi-centre prospective trials.

PSMA Expression in Solid Tumors beyond the Prostate Gland: Ready for Theranostic Applications?

In the past decades, the expanding use of prostate-specific membrane antigen (PSMA) imaging for prostate cancer has led to the incidental detection of a lot of extra-prostatic malignancies showing an increased uptake of PSMA. Due to these incidental findings, the increasing amount of immunohistochemistry studies and the deeper knowledge of the mechanisms of expression of this antigen, it is now clear that “PSMA” is a misnomer, since it is not specific to the prostate gland. Nevertheless, this lack of specificity could represent an interesting opportunity to bring new insights on the biology of PSMA and its sites of expression to image and treat new conditions, particularly several cancers. In this review, we will describe the main extra-prostatic cancers that exhibit PSMA expression and that can be studied with PSMA-based positron emission tomography–computed tomography (PET/CT) as an additional or alternative tool to conventional imaging. In particular, we will focus on cancers in which a radioligand therapy with ¹⁷⁷lutetium has been attempted, aiming to provide an overview of the possible future theragnostic applications of PSMA.

The Role of 18F-FLT PET/CT in Assessing Early Response to Transarterial Radioembolization and Chemoembolization in Patients with Primary and Metastatic Liver Tumors

Objectives

Metastases and primary malignancies are common in the liver. Local ablative applications such as transarterial chemoembolization (TACE), and transarterial radioembolization (TARE) provide minimally invasive and safe treatment in unresectable liver tumors. Early detection of response to treatment prevents unnecessary toxicity and cost in non-responder patients and provides an earlier use of other options that may be effective. This study aimed to identify the role of ¹⁸F-fluorothymidine (FLT) positron emission tomography/computed tomography (PET/CT) in the assessment of early response to TACE and TARE treatments in patients with unresectable primary and metastatic liver tumors.

Methods

This single-center study included 63 patients who underwent ¹⁸F-FLT PET/CT for response evaluation after TACE and TARE. After excluding 20 patients whose data were missing 43 TARE-receiving patients were analyzed. The compatibility of change in semi-quantitative values obtained from the ¹⁸F-FLT PET/CT images with the treatment responses detected in ¹⁸F-fluorodeoxyglucose PET/CT, CT, and MR images and survival was evaluated.

Results

There was no correlation between early metabolic, morphological response, and ¹⁸F-FLT uptake pattern, and change in standardized uptake values (SUV) which were ΔSUV_max, ΔSUV_mean, ΔSUV_peak., ΔSUV_mean, Δ SUV_peak values. There was no significant correlation between ¹⁸F-FLT uptake pattern, ΔSUV_max, ΔSUV_mean, ΔSUV_peak, and overall survival, progression-free survival (PFS) for the target lobe PFS for the whole-body. The survival distributions for the patients with >30% change in Δ SUV_max and ΔSUV_peak values were statistically significantly longer than the patients with <30% change (p<0.009 and p<0.024, respectively).

Conclusion

There was significant longer PFS for target liver lobe in patients with more than 30% decrease in ¹⁸F-FLT SUV_max and SUV_peak of the liver lesion in primary and metastatic unresectable liver tumors undergoing TARE.

TCP post-radioembolization and TCP post-EBRT in HCC are similar and can be predicted using the in vitro radiosensitivity

Background

Tumor equivalent uniform dose (EUD) is proposed as a predictor of patient outcome after liver radioembolization (RE) of hepatocellular carcinoma (HCC) and can be evaluated with ⁹⁰Y-TOF-PET. The aim is to evaluate the correlation between PET-based tumors EUD and the clinical response evaluated with dual molecular tracer (¹¹C-acetate and ¹⁸F-FDG) PET/CT post-RE.

Methods

34 HCC tumors in 22 patients were prospectively evaluated. The metabolic response was characterized by the total lesion metabolism variation (ΔTLM) between baseline and follow-up. This response allowed to compute a tumor control probability (TCP) as a function of the tumor EUD.

Results

The absorbed dose response correlation was highly significant (R = 0.72, P < 0.001). With an absorbed dose threshold of 40 Gy, the metabolic response was strongly different in both groups (median response 35% versus 100%, P < 0.001). Post-RE TCP as a function of the EUD was very similar to that observed in external beam radiation therapy (EBRT), with TCP values equal to 0.5 and 0.95 for a EUD of 51 Gy and 100 Gy, respectively. The TCP was perfectly predicted by the Poisson model assuming an inter tumor radiosensitivity variation of 30% around the HCC cell in vitro value.

Conclusions

EUD-based ⁹⁰Y TOF-PET/CT predicts the metabolic response post-RE in HCC assessed using dual molecular PET tracers and provides a similar TCP curve to that observed in EBRT. In vivo and in vitro HCC radiosensitivities are similar. Both TCPs show that a EUD of 100 Gy is needed to control HCC for the three devices (resin spheres, glass spheres, EBRT). Observed absorbed doses achieving this 100 Gy-EUD ranged from 190 to 1800 Gy!

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-022-00911-0.

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.

Optimization of the Clinical Effectiveness of Radioembolization in Hepatocellular Carcinoma with Dosimetry and Patient-Selection Criteria

Selective internal radiation therapy (SIRT) is part of the treatment strategy for hepatocellular carcinoma (HCC). Strong clinical data demonstrated the effectiveness of this therapy in HCC with a significant improvement in patient outcomes. Recent studies demonstrated a strong correlation between the tumor response and the patient outcome when the tumor-absorbed dose was assessed by nuclear medicine imaging. Dosimetry plays a key role in predicting the clinical response and can be optimized using a personalized method of activity planning (multi-compartmental dosimetry). This paper reviews the main clinical results of SIRT in HCC and emphasizes the central role of dosimetry for improving it effectiveness. Moreover, some patient and tumor characteristics predict a worse outcome, and toxicity related to SIRT treatment of advanced HCC patient selection based on the performance status, liver function, tumor characteristics, and tumor targeting using technetium-99m macro-aggregated albumin scintigraphy can significantly improve the clinical performance of SIRT.

Clinical and metabolic parameters for predicting disease progression of gallbladder adenocarcinoma

OBJECTIVE

This study aimed to identify reliable predictors of disease progression in patients with gallbladder (GB) adenocarcinoma.

PATIENTS AND METHODS

A total of 54 patients with GB adenocarcinoma underwent preoperative F-18 fluorodeoxyglucose (FDG) PET/CT. Age, sex, clinical stage, and pathologic differentiation were collected. Tumor size and PET parameters such as SUVmax, SUVmean, SUVpeak, metabolic tumor volume (MTV), and total lesion glycolysis were measured. Univariate and multivariate logistic regression analyses were performed to determine the utility of clinical values and PET parameters. Pearson bivariate correlation was used to evaluate the association between progression-free survival (PFS) and various parameters.

RESULTS

No recurrence was found in 15 of 54 patients, while six showed recurrence and another 33 manifested disease progression. There were significant differences in size, stage, pathologic differentiation, and PET parameters between the groups with and without recurrence/progression. However, there was no difference in those parameters between the groups with recurrence and progression. The average PFS of the groups with no recurrence, recurrence, and progression groups was 33.1, 17.1, and 5.0 months, respectively. In univariate analysis, age, sex, clinical stage, pathologic differentiation, size, and PET parameters were correlated with PFS. In multivariate analysis, only clinical stage and MTV were statistically significant and MTV showed the highest odds ratio. Pearson correlation coefficients showed moderate negative correlations between PFS and clinical stage or MTV.

CONCLUSION

In GB adenocarcinoma, clinical stage and MTV are the most powerful parameters for predicting recurrence and disease progression. Based on clinical stage, MTV will represent a strong prognostic predictor.

Evolving therapeutic strategies for advanced hepatocellular carcinoma

Introduction: While sorafenib dominated the therapeutic arena in advanced hepatocellular carcinoma (HCC) for almost a decade, newer agents and combinations have been changing the therapeutic landscape in the last years.Areas covered: The authors outline the etiopathogenesis and evaluate the diagnostics in HCC, followed by a comprehensive review of the currently approved and experimental treatment approaches, with a focus on various systemic agents and combinations of agents. The manuscript was subdivided into relevant categories, thus making it applicable for both clinical practice and research endeavors.Expert opinion: Recently, combination therapies including immune checkpoint inhibitors with anti-VEGF/R agents have shown superior clinical efficacy in HCC. The Atezolizumab-bevacizumab combination is currently the preferred first-line therapy. Single-agents cabozantinib and regorafenib as well as nivolumab-ipilimumab combination are favored as second-line therapies. Further research is needed to identify the predictors of response to various treatments and establish the distinct patient profiles that will derive most benefit. Tumor mutation analysis and germline mutation testing could identify rational therapeutic targets in HCC in the near future. As the skyline for new therapeutic agents and combinations in HCC continues to expand, the outlook as of today is cautiously optimistic in this still difficult-to-treat malignant neoplastic disease.

68Ga-PSMA PET/CT Versus 18F-FDG PET/CT for Imaging of Hepatocellular Carcinoma

Objectives:

This study aimed to compare the metabolic parameters obtained from ¹⁸fluorine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and gallium-68 (⁶⁸Ga)-prostate-specific membrane antigen (PSMA) PET/CT and investigate the relationship between serum alpha-fetoprotein and PET scan parameters in patients with hepatocellular carcinoma.

Methods:

Fourteen patients were recruited after dynamic magnetic resonance imaging (MRI) of the upper abdomen, and ¹⁸F-FDG and ⁶⁸Ga-PSMA PET/CT imaging studies were conducted. Regions of interest (ROIs) were drawn from lesion-free liver tissue, abdominal aorta (A), and right medial gluteal muscle (G) for the background activity. Maximum standard uptake value (SUV_max) of these regions were compared with the SUV_max of primary tumor (T).

Results:

On visual assessment, five patients (36%) experienced low ¹⁸F-FDG uptake in the primary lesion, three patients (21%) experienced moderate uptake, and six patients (43%) experienced high uptake. However, only one patient (7%) showed low ⁶⁸Ga-PSMA uptake, two patients (14%) showed moderate uptake, and 11 patients (79%) showed high uptake. Four patients with a low ¹⁸F-FDG uptake showed high ⁶⁸Ga-PSMA uptake, while one patient exhibited low uptake with both ¹⁸F-FDG and ⁶⁸Ga-PSMA. The number of lesions on ⁶⁸Ga-PSMA PET/CT and MRI was significantly higher than ¹⁸F-FDG PET/CT (p=0.042 and 0.026, respectively). T/A and T/G values were significantly higher in ⁶⁸Ga-PSMA than ¹⁸F-FDG (p=0.002 and 0.002, respectively).

Conclusion:

⁶⁸Ga-PSMA PET/CT is superior to ¹⁸F-FDG PET/CT in the staging of hepatocellular carcinoma. High ⁶⁸Ga-PSMA uptake could be promising for PSMA-targeted radionuclide treatments.

Practice and prospects for PET/CT guided interventions

During the past 10 years, performing real-time molecular imaging with positron emission tomography (PET) in combination with computed tomography (CT) during interventional procedures has undergone rapid development. Keeping in mind the interest of the nuclear medicine readers, an update is provided of the current workflows using real-time PET/CT in percutaneous biopsies and tumor ablations. The clinical utility of PET/CT guided biopsies in cancer patients with lung, liver, lymphoma, and bone tumors are reviewed. Several technological developments, including the introduction of new PET tracers and robotic arms as well as opportunities provided through acquiring radioactive biopsy specimens are briefly reviewed.

The frequency of occult solid malignancy in patients with polymyalgia rheumatica-like symptoms

Aims:

We aim to evaluate the clinical usefulness of systematic screening for occult cancer in patients with polymyalgia rheumatic (PMR)-like symptoms in real-life practice.

Methods:

All patients seen by rheumatologists in Burgundy, France, between March 2016 and December 2018 for new-onset PMR that met the 2012 ACR/EULAR classification criteria were prospectively included. Patients underwent systematic screening including determination of the erythrocyte sedimentation rate, serum C-reactive protein levels, thoracic, abdominal and pelvic computed tomography (CT-TAP) and, in men, serum prostate-specific antigen. The standardized incidence ratio (SIR) for cancers was calculated using 2012 national estimates of cancer incidence. Potential predictive factors for the diagnosis of cancer were then evaluated using univariate and multivariate analyses.

Results:

Among the 118 patients included, nine cases of cancer were confirmed and diagnosed with CT-TAP: kidney carcinoma (n = 4), lung cancer (n = 2), pancreatic, colon, and ampullary carcinoma (n = 1 each). Among these cancers, five were localized (four kidney, and one ampullary carcinoma) and were treated with complete surgical resection. The expected incidence of cancer in the general population was 1.95, leading to an overall SIR of 4.6 (95% CI 2.4–8.9, p < 0.0001). An additional analysis was performed for the kidney carcinoma, and it showed a highly significant increase in SIR: 80.8 (95% CI 30.3–215.4). In 80% of patients, the PMR-like syndrome regressed during cancer treatment. No other predictive factors for cancer were found.

Conclusion:

Systematic screening for cancer including CT-TAP in real-life practice revealed occult solid malignancy, mostly early-stage cancer, in a relevant proportion of patients presenting PMR-like symptoms. The high proportion of kidney cancer (40%) is worth highlighting, especially considering that it is not one of the most frequent cancers after 50 years of age.

PET/MRI of the hepatobiliary system: Review of techniques and applications

Simultaneous positron emission tomography and MRI (PET/MRI) is an emerging technology that offers the benefits of MRI, including excellent soft tissue contrast, lack of ionizing radiation, and functional MRI techniques, with the physiologic information provided by PET. Although most PET/MRI systems are currently installed in tertiary care centers, PET/MRI technology is becoming increasingly widespread. The usefulness of PET/MRI varies by tumor type and organ system and has been shown to have utility in evaluation of primary and secondary hepatic neoplasms. Understanding the appropriate applications, techniques and relevant imaging findings is important for practicing radiologists considering or currently utilizing PET/MR for the evaluation of primary liver neoplasms, including hepatocellular carcinoma (HCC), as well as staging of biliary neoplasms including cholangiocarcinoma and gallbladder cancer, identification of liver metastases, and staging of neuroendocrine tumor.

Comparative Findings Between 68Ga-PSMA and 18F-FDG PET/CT for Hepatocellular Carcinoma

We have reported here the case of a 69-year-old man who presented with spinal cord compression due to bone metastases as the first manifestation of hepatocellular carcinoma (HCC). For the initial staging, the patient underwent ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) imaging, which demonstrated mild ¹⁸F-FDG uptake in the multiple expansile osteolytic bone lesions, but no remarkable atypical ¹⁸F-FDG uptake in the liver lesion on low-doses CT. An additional PET/CT scan was performed to evaluate the prostate-specific membrane antigen (PSMA) expression, which has recently been reported to be a potential biological marker in a variety of tumors including HCC. High PSMA uptake was recorded in both the metastatic bone lesions and the primary liver lesion/tumor by the ⁶⁸Ga-PSMA PET/CT.

Differences in 18F-FDG Uptake and Expression of Glucose Transporter Between 2 Distinct Subtypes of Mass-Forming Intrahepatic Cholangiocarcinomas

PURPOSE

Recently, intrahepatic cholangiocarcinoma (iCCA) has been classified into small duct cholangiocarcinoma (SDC) and large duct cholangiocarcinoma (LDC) according to the origin of the biliary tree. Although the usefulness of F-FDG PET/CT in iCCA is well known, there are no reports evaluating differences in accumulation of F-FDG according to the recently described iCCA subtypes. The aim of this study was therefore to assess F-FDG accumulation and the expression of glucose transporters in SDC and LDC.

METHODS

Our institutional review board approved this retrospective study and waived the requirement for informed consent. Fourteen consecutive surgically resected mass-forming iCCA (7 SDCs, 23 ± 6.7 mm; 7 LDCs, 44 ± 26 mm) were enrolled. The SUVmax on F-FDG PET/CT and the expression of glucose transporter 1 (Glut-1), Glut-2, hexokinase 2 (HK2), and glucose-6-phosphatase by immunohistochemistry were evaluated and compared between SDC and LDC.

RESULTS

The SUVmax in SDC was significantly lower than that in LDC (3.2 ± 0.8 vs 7.6 ± 3.2, P < 0.01). The staining scores of Glut-1 and HK2 were significantly lower in SDC than in LDC (0 vs 3 ± 1.4, P = 0.0034; 1.6 ± 1.1 vs 3.4 ± 1.1, P = 0.014, respectively). Expression levels of Glut-2 and glucose-6-phosphatase were variable and did not show a significant difference between SDC and LDC. Overall survival was significantly worse in LDC than in SDC (P = 0.01).

CONCLUSIONS

F-FDG accumulation and Glut-1 and HK2 expression were significantly higher in LDC than in SDC. A low-glycolytic feature may be one of the characteristic findings of SDC.

Primary Hepatocellular Carcinoma With Intense 68Ga-PSMA Uptake But Slight 18F-FDG Uptake on PET/CT Imaging

Ga-PSMA PET/CT imaging is an emerging imaging modality in prostate cancer. PSMA expression is also reported for nonprostate malignancies, including primary hepatocellular carcinoma. Herein, we present a case of a 74-year-ald man with recently diagnosed hepatocellular carcinoma who was referred for F-FDG PET/CT imaging for initial staging. The patient underwent F-FDG PET/CT as part of staging procedure; he also underwent Ga-PSMA PET/CT. PET/CT images revealed only slight F-FDG uptake in the liver lesion, but intense Ga-PSMA uptake, without any metastatic lesion seen elsewhere in the body.

Radio-pathological Correlation of 18F-FDG PET in Characterizing Gallbladder Wall Thickening

AIM

Thick-walled gallbladder is difficult to characterize on conventional imaging. 18F-FDG PET was used to differentiate benign and malignant wall thickness and compared with histopathology.

METHODS

Thirty patients with gallbladder (GB) wall thickening (focal > 4 mm and diffuse > 7 mm), underwents uspected on  ultrasound, or CT scan, and underwent 18F-FDG PET. Histopathology of the specimen was compared with imaging findings.

RESULTS

The mean age was 48.22 ± 31.33 years with a M:F 1:4 ratio. Twenty patients had diffuse and 10 had focal thickening. On 18F-FDG PET, lesion was benign in 12, malignant in 13, and indeterminate in 5. Histopathology was malignancy in 12; benign in 18-chronic cholecystitis in 11, xanthogranulomatous in 4, IgG4 related in 2, and polyp in 1. The mean GB wall thickness was 7.79 ± 3.59 mm (10.34 malignant and 6.10 in benign, p = 0.001). At a cutoff of 8.5 mm, the sensitivity and specificity of detecting malignancy was 94% and 67%. The mean SUV uptake was 7.46 (benign 4.51, malignant 14.26, p = 0.0102). At a cutoff of 5.95, the sensitivity and specificity of detecting malignancy was 92% and 79%. For 18F-FDG PET, overall sensitivity was 91%, specificity 79%, PPV 77%, NPV 92%, and diagnostic accuracy was 84%.

CONCLUSION

18F-FDG PET is a reliable method of differentiation between benign and malignant thickening of the gallbladder particularly when wall thickness and SUV value is taken into account.

FDG-PET/CT imaging findings of hepatic tumors and tumor-like lesions based on molecular background

The usefulness of whole-body 18-fluoro-2-deoxyglucose (FDG)-fluorodeoxyglucose positron emission (PET)/computed tomography (CT) is established for assessment of disease staging, detection of early disease recurrence, therapeutic evaluation, and predicting prognosis in various malignancies; and for evaluating the spread of inflammation. However, the role of FDG-PET/CT for the liver is limited because CT and magnetic resonance imaging (MRI) can provide an accurate diagnosis of most tumors. In addition, in other potentially useful roles there are several pitfalls in the interpretation of FDG uptake in PET/CT imaging. Accurate evaluation demands knowledge of the FDG uptake of each lesion, including potential negative and positive uptakes, and requires an understanding of the underlying background of the molecular mechanisms. The degree of FDG uptake is dependent on cellular metabolic rate and the expression of glucose transporter, hexokinase, and glucose-6-phosphatase, which in turn are closely affected by biological characteristics such as pathological category (e.g., adenocarcinoma, squamous cell carcinoma, small cell cancer, transitional cell cancer, neuroendocrine tumor, sarcoma, lymphoma), tumor differentiation, histological behavior (e.g., solid, cystic, mucinous), and intratumoral alterations (e.g., necrosis, degeneration, hemorrhage). Correlation with the CT and MRI findings, which also precisely depict the pathological findings, is important to avoid misdiagnosis.

Clinical and Translational Research Challenges in Biliary Tract Cancers

BACKGROUND

Biliary Tract Cancers (BTC) are rare malignancies with a poor prognosis. There are many challenges encountered in treating these patients in daily practice as well as in clinical, translational and basic research.

OBJECTIVE

This review summarises the most relevant challenges in clinical and translational research in BTCs and suggests potential solutions towards an improvement in quality of life and outcomes of patients diagnosed with such malignancies.

FINDINGS

The main challenge is the low number of patients with BTCs, complicated by the aggressive natural behaviour of cancer and the lack of funding sources for research. In addition, the clinical characteristics of these patients and the specific cancer-related complications challenge clinical research and clinical trial recruitment. It is worth highlighting that BTCs are a group of different malignancies (cholangiocarcinoma, gallbladder cancer and ampullary cancer) rather than a unique homogeneous disease. These subgroups differ not only in molecular aspects, but also in clinical and demographic characteristics. In addition, tailored imaging and quality of life assessment are required to tackle some of the issues specific to BTCs. Finally, difficulties in tissue acquisition both in terms of biopsy size and inclusion of sufficient tumour within the samples, may adversely impact translational and basic research.

CONCLUSION

Increasing awareness among patients and clinicians regarding BTC and the need for further research and treatment development may address some of the main challenges in BTC research. International collaboration is mandatory to progress the field.

Evidence of Prostate-Specific Membrane Antigen Expression in Hepatocellular Carcinoma Using 68Ga-PSMA PET/CT

Prostate specific membrane antigen (PSMA) expression has been demonstrated in tumor neovasculature of many solid tumors, including hepatocellular carcinoma (HCC). The purpose of this study is to evaluate PSMA expression in patients with HCC.

MATERIALS AND METHODS

Nineteen HCC patients who underwent F-fluorodeoxyglucose (F-FDG) positron emission tomography (PET) as part of restaging procedure also underwent Ga-PSMA PET. F-FDG PET and Ga-PSMA findings were compared visually as well as quantitatively using maximized standardized uptake values (SUVmax).

RESULTS

FDG was positive in 15 patients while 16 patients demonstrated PSMA expression. The only extrahepatic finding was one metastatic lymph node detected by both tracers. Mean SUVmax of liver lesions on FDG PET/CT was 8.3 ± 2.3 and mean tumor to background ratio was 2.3 ± 1.5. Respective values for Ga-PSMA PET/CT were 17.4 ± 9 and 3.3 ± 2.2. On visual and quantitative evaluation uptake was higher with PSMA in nine patients and higher with FDG in four patients. PSMA and FDG activity were similar in three patients. One of the FDG positive patients was PSMA negative whereas two patients were PSMA positive but FDG negative. Heterogeneous uptake pattern was observed in three patients. Comparison of mean SUVmax and T/B values between PET studies revealed no statistically significant difference (P > 0.1). The mean survival was 25 months (range: 18-32 months) and SUVmax of PSMA (P = 0.05) and FDG (P = 0.012) showed medium strength of correlation with overall survival.

CONCLUSION

PSMA expression in advanced HCC can be demonstrated by Ga-PSMA PET but is not superior to FDG PET however it could be useful for identifying patients with limited therapeutic options.

Current Imaging Standards for Nonmetastatic Benign and Malignant Liver Tumors

The accurate diagnosis of a liver mass can usually be established with a thorough history, examination, laboratory inquiry, and imaging. The necessity of a liver biopsy to determine the nature of a liver mass is rarely necessary. Contrast-enhanced computed tomography and magnetic resonance are the standard of care for diagnosing liver lesions and high-quality imaging should be performed before performing a biopsy. This article discusses current consensus guidelines for imaging of liver masses, as well as masses found on surveillance imaging. The ability to accurately characterize lesions requires proper use and understanding of the technology and expert interpretation.

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

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

Value of 18F-FDG PET/CT in the diagnosis of portal vein tumor thrombus in patients with hepatocellular carcinoma

OBJECTIVE

The aim of this study was to evaluate the usefulness of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for the diagnosis of a portal vein tumor thrombus (PVTT) in patients with hepatocellular carcinoma (HCC).

METHODS

One hundred fifty-four patients with histologically proven HCC underwent ¹⁸F-FDG PET/CT imaging. The maximum standardized uptake value (SUVmax) was calculated, and the change in SUVmax (retention index, RI) was defined as the ratio of the increase in SUVmax between early and delayed scans to the SUVmax in the early scan. The circular region of interest was placed on the transaxial images according to the corresponding CT images. The final diagnoses of a PVTT were confirmed by histopathology.

RESULTS

Of the patients examined, 101 (65.6%) had no confirmed instances of a PVTT, whereas 53 (34.4%) had a confirmed PVTT. The sensitivity of ¹⁸F-FDG PET/CT imaging was 62.3%, the specificity was 97.0%, the accuracy was 85.1%, the positive predictive value was 91.7%, and the negative predictive value was 83.1%. The SUVmax of the PVTT was 4.32 ± 1.96 and the SUVmax of the HCC lesions for these patients was 5.38 ± 2.79, but these differences were insignificant (t = 1.78, p = 0.08). For dual-time-point imaging, the SUV1 of the PVTT lesions was 3.75 ± 1.48, and SUV2 was 3.63 ± 1.41, but these differences were insignificant (t = 0.82, p = 0.42). The SUV1 of the HCC lesions was 4.47 ± 2.03, and the SUV2 was 4.90 ± 2.07, which were both also insignificant (t = - 1.81, p = 0.09). The RI of the PVTT lesions was - 2.05 ± 19.96%, and the RI of the HCC lesions was 11.87 ± 26.20%, with no significant differences between them (t = 1.58, p = 0.13).

CONCLUSIONS

¹⁸F-FDG PET/CT may potentially improve the accurate diagnoses of a PVTT in patients with HCC.

18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) for patients with biliary tract cancer: Systematic review and meta-analysis

BACKGROUND & AIMS

The role of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸FDG-PET) in the diagnosis and staging of patients with biliary tract cancers (BTCs) remains controversial, so we aimed to provide robust information on the utility of ¹⁸FDG-PET in the diagnosis and management of BTC.

METHODS

This systematic review and meta-analysis explored the diagnostic test accuracy of ¹⁸FDG-PET as a diagnostic tool for diagnosis of primary tumour, lymph node invasion, distant metastases and relapsed disease. Subgroup analysis by study quality and BTC subtype were performed. Changes in management based on ¹⁸FDG-PET and impact of maximum standardised uptake values (SUVmax) on prognosis were also assessed. A random effects model was used for meta-analyses.

RESULTS

A total of 2,125 patients were included from 47 eligible studies. The sensitivity (Se) and specificity (Sp) of ¹⁸FDG-PET for the diagnosis of primary tumour were 91.7% (95% CI 89.8-93.2) and 51.3% (95% CI 46.4-56.2), respectively, with an area under the curve (AUC) of 0.8668. For lymph node invasion, Se was 88.4% (95% CI82.6-92.8) and Sp was 69.1% (95% CI 63.8-74.1); AUC 0.8519. For distant metastases, Se was 85.4% (95% CI 79.5-90.2) and Sp was 89.7% (95% CI86.0-92.7); AUC 0.9253. For relapse, Se was 90.1% (95% CI 84.4-94.3) and Sp was 83.5% (95% CI 74.4-90.4); AUC 0.9592. No diagnostic threshold effect was identified. Meta-regression did not identify significant sources of heterogeneity. Sensitivity analysis revealed no change in results when analyses were limited to studies with low risk of bias/concern. The pooled proportion of change in management was 15% (95% CI 11-20); the majority (78%) due to disease upstaging. Baseline high SUVmax was associated with worse survival (pooled hazard ratio of 1.79; 95% CI 1.37-2.33; p <0.001).

CONCLUSIONS

There is evidence to support the incorporation of ¹⁸FDG-PET into the current standard of care for the staging (lymph node and distant metastases) and identification of relapse in patients with BTC to guide treatment selection; especially if the identification of occult sites of disease would change management, or if diagnosis of relapse remains unclear following standard of care imaging. The role for diagnosis of the primary tumour remains controversial due to low sensitivity and ¹⁸FDG-PET should not be considered as a replacement for pathological confirmation in this setting.

LAY SUMMARY

A positron emission tomography (PET scan), using ¹⁸F-fluorodeoxyglucose (¹⁸FDG), can help doctors identify areas of cancer in the body by highlighting "hot spots". These hotspots may be cancerous (true positive) but may also be non-cancerous, like inflammation (false positive). We show that PET scans are useful to assess how far advanced the cancer is (by assessing spread to lymph glands and to other organs) and also to identify if the cancer has recurred (for example after surgery), thus helping doctors to make treatment decisions. However, a biopsy is still needed for the initial diagnosis of a biliary tract cancer, because of the high chance of a "false positive" with PET scans.

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.

Primary hepatoid adenocarcinoma of the orbit

PURPOSE

To report a case of primary hepatoid adenocarcinoma of the orbit.

OBSERVATIONS

An adult patient was referred for evaluation of an orbital mass. Histopathology of the orbital biopsy indicated a carcinoma with hepatoid features. Laboratory studies revealed normal liver function tests, elevated serum alpha-fetoprotein, and whole-body positron emission tomography/computed tomography scan showed no evidence of liver involvement or an alternative primary origin.

CONCLUSIONS AND IMPORTANCE

To the authors' knowledge, this is the first reported case of primary hepatoid adenocarcinoma of the orbit.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Metabolic imaging for guidance of curative treatment of isolated pelvic implantation metastasis after resection of spontaneously ruptured hepatocellular carcinoma: A case report

Spontaneous rupture of hepatocellular carcinoma (HCC) is a life-threatening complication and its prognosis is significantly poor because of the high recurrence rate after initial hepatectomy. Resection of isolated extrahepatic metastasis of HCC has been advocated to obtain a possibility of long-term survival. However, it is a challenge for clinicians to detect implantation metastasis of spontaneously ruptured HCC. Accurate re-staging plays the most important role in making a decision on isolated metastasis resection. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is useful in detecting intra-abdominal implantation metastasis from a variety of malignancies and shows superior accuracy to conventional imaging modalities in determining the location of metastasis. We present one patient with a new isolated pelvic implantation metastasis detected by ¹⁸F-FDG PET/CT and pathologically confirmed by PET/CT-guided percutaneous biopsy, who had a history of resection of spontaneously ruptured HCC two years ago. The patient’s condition was stable at the 6-mo follow-up after resection of the isolated pelvic metastasis.

PET/MR Imaging in Cancers of the Gastrointestinal Tract

PET/computed tomography (PET/CT) is an established hybrid imaging technique for staging and follow-up of gastrointestinal (GI) tract malignancies, especially for colorectal carcinoma. Dedicated hybrid PET/MR imaging scanners are currently available for clinical use. Although they will not replace regular use of PET/CT, they may have utility in selected cases of GI tract malignancies. The superior soft tissue contrast resolution and depiction of anatomy and the functional information obtained from diffusion-weighted imaging (DWI) provided by MR imaging in PET/MR imaging are advantages over CT of PET/CT for T staging and follow-up of rectal carcinoma and for better characterization of liver lesions. Functional information from DWI and use of liver-specific MR imaging contrast agents are an added advantage in follow-up of liver metastases after systemic and locoregional treatment. New radiotracers will improve the utility of PET/MR imaging in staging and follow-up of tumors, which may not be [18F]-2-fluoro-2-deoxy-d-glucose avid, such as hepatocellular carcinoma and neuroendocrine tumors. PET/MR imaging also has application in selected cases of cholangiocarcinoma, gallbladder cancer, and pancreatic carcinoma for initial staging and follow-up assessment.

Approach to the Solitary Liver Lesion: Imaging and When to Biopsy

The characterization and management of focal liver lesions is a commonly encountered problem in radiology. While the imaging findings will often be diagnostic, in equivocal cases the decision of how to proceed may be challenging. The primary modalities for liver lesion characterization are multiphase contrast-enhanced computed tomography and magnetic resonance imaging. Most lesions have typical imaging features, and when taken in conjunction with patient demographics and biochemistry the diagnosis can usually be made. Ancillary imaging modalities such as contrast-enhanced ultrasound and hepatobiliary specific contrast agents are also useful. Cirrhotic livers present a challenge due to the spectrum of benign, dysplastic, and malignant nodules that can occur. The report should include information necessary for accurate staging, and published standardized reporting guidelines should be taken into consideration. A decision to proceed to biopsy should be made only after multidisciplinary review of the case. If biopsy is required, fine needle aspiration is usually sufficient, though core needle biopsy may be required in certain circumstances.

PET-avid hepatocellular adenomas: incidental findings associated with HNF1-α mutated lesions

BACKGROUND

Hepatocellular adenoma (HCA) is the second most common benign liver neoplasm and occurs predominantly in women in their reproductive years. Positron emission tomography (PET) using [18F] fluorodeoxyglucose (FDG) is commonly used in cancer staging, surveillance and evaluation of treatment response. PET-avid HCA are rare and can be falsely interpreted as malignancies.

METHODS

A retrospective review of four institutions' database was performed to identify the PET-avid HCAs with clinico-pathological correlation.

RESULTS

Nine patients with histological proven PET-avid HCA was identified. Eight out of 9 patients were female with a median age at diagnosis of 44 years. All patients' tumors with available histological subtyping (8/8) were HNF1-α mutated and had no inflammatory changes; 6 out the 9 lesions had prominent (>50%) steatotic changes.

CONCLUSION

Hepatocellular adenomas, specifically the HNF1-α subtype, can cause false-positive PET findings when seeking to identify malignancy. Concomitantly, PET-CT may have the potential to identify the HCA histopathologic variant with the lowest malignant and hemorrhagic potential.

Prediction of microvascular invasion of hepatocellular carcinoma using gadoxetic acid-enhanced MR and (18)F-FDG PET/CT

PURPOSE

To identify the gadoxetic acid-enhanced MR and the (18)F-fludeoxyglucose (FDG) PET/CT findings associated with microvascular invasion (MVI) of hepatocellular carcinoma (HCC) in patients who are undergoing liver transplantation (LT).

METHODS

Fifty-one patients with 78 HCCs underwent LT. Preoperative MRI and (18)F-FDG PET/CT findings were retrospectively analyzed and the association of the imaging findings with MVI was assessed.

RESULTS

Univariate analysis revealed that hypointensity seen on T1WI (OR = 4.329, p = 0.011), peritumoral enhancement (OR = 7.000, p = 0.008), inhomogeneity on arterial phase (OR = 4.321, p = 0.011), delayed phase (OR = 4.519, p = 0.009) or hepatobiliary phase (OR = 3.564, p = 0.032), and the large tumor size (>5 cm) (OR = 12.091, p = 0.001) showed statistically significant associations with MVI. The ratio of tumor maximum standardized uptake value (SUV) to normal liver mean SUV (TSUVmax/LSUVmean) (2.05 ± 1.43 vs. 1.08 ± 0.37) revealed significantly higher value in the MVI-positive group. Multivariate analysis revealed that peritumoral enhancement and a TSUVmax/LSUVmean of 1.2 or greater had a statistically significant association with MVI, with odds ratios of 10.648 (p = 0.016) and 14.218 (p = 0.001), respectively.

CONCLUSIONS

Preoperative imaging findings such as peritumoral enhancement seen on gadoxetic acid-enhanced MR and a TSUVmax/LSUVmean of 1.2 or more on (18)F-FDG PET/CT, may suggest the presence of MVI in HCC patients.

Diagnostic and therapeutic management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing health problem, representing the second cause of cancer-related mortality worldwide. The major risk factor for HCC is cirrhosis. In developing countries, viral hepatitis represent the major risk factor, whereas in developed countries, the epidemic of obesity, diabetes and nonalcoholic steatohepatitis contribute to the observed increase in HCC incidence. Cirrhotic patients are recommended to undergo HCC surveillance by abdominal ultrasounds at 6-mo intervals. The current diagnostic algorithms for HCC rely on typical radiological hallmarks in dynamic contrast-enhanced imaging, while the use of α-fetoprotein as an independent tool for HCC surveillance is not recommended by current guidelines due to its low sensitivity and specificity. Early diagnosis is crucial for curative treatments. Surgical resection, radiofrequency ablation and liver transplantation are considered the cornerstones of curative therapy, while for patients with more advanced HCC recommended options include sorafenib and trans-arterial chemo-embolization. A multidisciplinary team, consisting of hepatologists, surgeons, radiologists, oncologists and pathologists, is fundamental for a correct management. In this paper, we review the diagnostic and therapeutic management of HCC, with a focus on the most recent evidences and recommendations from guidelines.

Anticancer activity using positron emission tomography-computed tomography and pharmacokinetics of β-eudesmol in human cholangiocarcinoma xenografted nude mouse model

Cholangiocarcinoma (CCA) is an important public health problem in several parts of South East Asia, particularly in Thailand. The limited availability of effective diagnostic tools for early stage CCA, including chemotherapeutic options, constitutes a major problem for treatment and control of CCA. The aim of the present study was to assess the anti-CCA activity and pharmacokinetics of β-eudesmol in CCA-xenografted nude mouse model and healthy mice. Positron emission tomography-computed tomography (PET-CT) with (18)F-fluorodeoxyglucose was used for detecting and monitoring tumour development, and PET-CT with technetium-99m was used to investigate its pharmacokinetics property. Results support the role of PET-CT as a potential tool for detecting and monitoring the progress of lung metastasis. Tumour size and lung metastasis were significantly inhibited by 91.6% (of baseline) and 95% (of total lung mass), respectively, following treatment with high-dose β-eudesmol (100 mg/kg body weight for 30 days). Survival time was prolonged by 64.4% compared with untreated controls. Systemic clearance of the compound was rapid, particularly during the first 60 min. The compound was distributed to the vital organs at maximum levels 2 h after oral administration and 15 min after intravenous injection. Results from the present study suggest the potential of β-eudesmol as a promising candidate for further development as an anti-CCA drug with respect to its pharmacodynamics and pharmacokinetic properties. PET-CT, with radiotracers (18)F-fluorodeoxyglucose and technetium-99m, was shown to be a reliable tool in the investigation of anti-CCA and pharmacokinetic properties of β-eudesmol in CCA-xenografted and healthy mice.

PET-avid hepatocellular adenomas: incidental findings associated with HNF1-α mutated lesions

BACKGROUND

Hepatocellular adenoma (HCA) is the second most common benign liver neoplasm and occurs predominantly in women in their reproductive years. Positron-emission tomography (PET) using [18F] fluorodeoxyglucose (FDG) is commonly used in cancer staging, surveillance and evaluation of the treatment response. PET-avid HCA is rare and can be falsely interpreted as malignancies.

METHODS

A retrospective review of four institutions' database was performed to identify the PET-avid HCAs with clinico-pathological correlation.

RESULTS

Nine patients with histological proven PET-avid HCA was identified. Eight out of nine patients were female with a median age at diagnosis of 44 years. All patients' tumours with available histological subtyping (8/8) were HNF1-α mutated and had no inflammatory changes; six out the nine lesions had prominent (>50%) steatotic changes.

CONCLUSION

Hepatocellular adenomas, specifically the HNF1-α subtype, can cause false-positive PET findings when seeking to identify malignancy. Concomitantly, PET-CT may have the potential to identify the HCA histopathological variant with the lowest malignant and haemorrhagic potential.

Biphenotypic hepatic tumors: imaging findings and review of literature

PURPOSE

To describe imaging findings in biphenotypic hepatic tumors (BPT) and a proposal for new imaging classification based on contrast-enhanced imaging.

METHODS

Retrospective review of CT, MRI, PET/CT, and ultrasound findings in 39 patients with histologically confirmed BPT was performed. Tumor markers including AFP, L3 fraction, CA 19.9, CA 125, and CEA were recorded. Based on the dynamic enhancement features, BPT were categorized into 4 enhancement patterns (Types 1-4). Enhancement patterns were correlated with other imaging findings and tumor markers. Imaging features and tumor markers that were not consistent with diagnosis of hepatocellular carcinoma or intrahepatic cholangiocarcinoma based on enhancement pattern were considered discordant findings.

RESULTS

Enhancement patterns in 29 patients (CT/MR) included 23 Type 2 (continuous peripheral rim of late arterial hyperenhancement with washout or fade in portal venous and/or delayed phases, ±delayed central enhancement) and 2 of each Types 1, 2, and 3. Discordant imaging findings were present in two patients with Type 2 pattern and in one patient with Type 1 pattern. Both AFP and CA 19.9 were elevated in 15 of 33 of patients. Tumor markers AFP and CA 19.9 were discordant in 17 of 21 patients with Type 2 pattern, two of two patients with Type 3 pattern. Most BPTs were markedly PET avid with average SUV max of 8.2. Most frequent ultrasound appearance is peripheral hypoechogenicity and central hyperechogenicity.

CONCLUSIONS

BPT most commonly present with imaging features similar to cholangiocarcinoma or metastases. BPT can be suggested when imaging findings or tumor markers are discordant with the most likely diagnosis based on enhancement pattern.