Positron emission tomography/computed tomography with 18F-fluorodeoxyglucose identifies tumor growth or thrombosis in the portal vein with hepatocellular carcinoma

Advancements in hepatocellular carcinoma management: the role of 18F-FDG PET-CT in diagnosing portal vein tumor thrombosis

Portal vein thrombosis, a relatively frequent complication associated with hepatocellular carcinoma (HCC) and liver cirrhosis, is recognized as a significant global health concern. This is mainly due to these conditions' high prevalence and potentially severe outcomes. The aim of our study was to conduct a comprehensive literature review to evaluate the efficacy, accuracy, and clinical implications of 18F-FDG PET-CT in diagnosing and managing portal vein tumor thrombosis (PVTT) in patients with HCC. HCC, which accounts for 80% of liver malignancies, ranks as the fourth most prevalent cancer globally and is a significant contributor to cancer-related mortality. The majority of HCC patients are diagnosed at an advanced stage, leading to a deterioration in patient outcomes. Involvement of the portal vein is also a significant negative factor. This review analyzes the application of 18F-FDG PET-CT in the detection and management of PVTT in patients with HCC, with an emphasis on the importance of the maximum standardized uptake value as an essential diagnostic and prognostic marker. 18F-FDG PET-CT is invaluable for detecting recurrence and guiding management strategies, particularly in patients with high-grade HCC, and plays a pivotal role in differentiating malignant portal vein thrombi from their benign counterparts.

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.

The role of 18F-FDG PET/CT in differentiating malignant from benign portal vein thrombosis

AIMS

In this retrospective study, we evaluated the role of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in differentiating malignant from benign portal vein thrombosis (PVT) in patients with known malignant tumors.

METHODS

Seventy-two patients with histologically or clinically confirmed PVT and who had undergone (18)F-FDG PET/CT were included. Visual and semiquantitative analyses of PET/CT scans were performed. Metabolic activity was measured using the maximum standardized uptake value (SUVmax) by drawing the region of interest at the site of thrombosis. Receiver operating characteristic analysis was conducted to identify the optimal cutoff of SUVmax for detecting neoplastic thrombosis. Malignancy was defined using the following criteria: (1) visual analysis and (2) SUVmax >3.35. PET/CT results were confirmed with histopathological results and clinical and imaging follow-up.

RESULTS

The SUVmax of tumor thrombus (6.37 ± 2.67) was significantly higher than that of bland thrombus (2.87 ± 1.47; P < 0.01). The sensitivities, specificities, and accuracies for the two criteria were 91.5 % and 93.6; 64.0 and 80.0 %; and 81.9 % and 88.9 %, respectively.

CONCLUSION

(18)F-FDG PET/CT is a promising new method for distinguishing between portal venous neoplastic thrombosis and bland thrombosis using semiquantitative analysis, with the optimal cutoff value of SUVmax >3.35 as a criterion.

FDG-Avid Portal Vein Tumor Thrombosis from Hepatocellular Carcinoma in Contrast-Enhanced FDG PET/CT

OBJECTIVES

In this study, we aimed to describe the characteristics of portal vein tumor thrombosis (PVTT), complicating hepatocellular carcinoma (HCC) in contrast-enhanced FDG PET/CT scan.

METHODS

In this retrospective study, 9 HCC patients with FDG-avid PVTT were diagnosed by contrast-enhanced fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), which is a combination of dynamic liver CT scan, multiphase imaging, and whole-body PET scan. PET and CT DICOM images of patients were imported into the PET/CT imaging system for the re-analysis of contrast enhancement and FDG uptake in thrombus, the diameter of the involved portal vein, and characteristics of liver tumors and metastasis.

RESULTS

Two patients with previously untreated HCC and 7 cases with previously treated HCC had FDG-avid PVTT in contrast-enhanced FDG PET/CT scan. During the arterial phase of CT scan, portal vein thrombus showed contrast enhancement in 8 out of 9 patients (88.9%). PET scan showed an increased linear FDG uptake along the thrombosed portal vein in all patients. The mean greatest diameter of thrombosed portal veins was 1.8 ± 0.2 cm, which was significantly greater than that observed in normal portal veins (P<0.001). FDG uptake level in portal vein thrombus was significantly higher than that of blood pool in the reference normal portal vein (P=0.001). PVTT was caused by the direct extension of liver tumors. All patients had visible FDG-avid liver tumors in contrast-enhanced images. Five out of 9 patients (55.6%) had no extrahepatic metastasis, 3 cases (33.3%) had metastasis of regional lymph nodes, and 1 case (11.1%) presented with distant metastasis. The median estimated survival time of patients was 5 months.

CONCLUSION

The intraluminal filling defect consistent with thrombous within the portal vein, expansion of the involved portal vein, contrast enhancement, and linear increased FDG uptake of the thrombus extended from liver tumor are findings of FDG-avid PVTT from HCC in contrast-enhanced FDG PET/CT.

Extensive tumor thrombus of hepatocellular carcinoma in the entire portal venous system detected on fluorodeoxyglucose positron emission tomography computed tomography

Detection of thrombus is usually an incidental finding on fluorodeoxyglucose positron emission tomography/computed tomography studies. Nevertheless this is an important finding in terms of disease prognostication and in planning the treatment strategy. We herein report a case of a 50-years-old male, a diagnosed case of hepatocellular carcinoma with extensive hypermetabolic thrombus involving the entire portal venous system.

FDG PET/CT appearance of portal vein tumor thrombus in the gastric primitive neuroectodermal tumor: uncommon primary tumor site with rare finding

Gastric primitive neuroectodermal tumor (PNET) is a very rare tumor. There are only a few case reports in the literature. Although cases with FDG uptake in the portal venous tumor thrombus (PVTT) in different primary malignancies have been evaluated before, the coexistence of PNET and PVTT has not been reported yet. Herein, we report the case of a gastric PNET with PVTT, which resolved after 3 cycles of polychemotherapy except for a residual tumor focus in the gastric corpus.

Predictive value of 18F-fluorodeoxyglucose PET/CT for transarterial chemolipiodolization of hepatocellular carcinoma

AIM: To investigate the correlation of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) with clinical features and the prediction of treatment response.

METHODS: A total of 83 hepatocellular carcinoma (HCC) patients undergoing ¹⁸F-FDG PET before transarterial chemolipiodolization with systemic chemo-infusion between October, 2006 and May, 2009 were retrospectively enrolled. The patients included 68 men and 15 women (mean age, 60 ± 10.7 years). The effect of ¹⁸F-FDG-monitored PET uptake on clinical features and on the evaluated treatment response was ascertained with modified Response Evaluation Criteria in Solid Tumors. The PET parameters of maximal standardized uptake value of the tumor (Tsuv_max), the ratio of the tumor maximal standardized uptake value (SUV) to the liver maximal SUV (Tsuv_max/Lsuv_max) and the ratio of tumor maximal SUV to the liver mean SUV (Tsuv_max/Lsuv_mean) were tested as predictive factors.

RESULTS: Among the 3 SUV parameters, the Tsuv_max/Lsuv_mean ratio (cutoff value of 1.90) was significantly associated with tumor burden including tumor size, tumor number, α-fetoprotein levels and tumor stage (P < 0.001, P = 0.008, P = 0.011, P < 0.001, respectively). The objective response rates in patients with a high SUV ratio (≥ 1.90) were significantly better than those with a low SUV ratio (< 1.90) (P = 0.020). The overall survival rates of patients exhibiting a low Tsuv_max/Lsuv_mean ratio (< 1.90) and those with a high SUV ratio (≥ 1.90) was 38.2 and 10.3 mo, respectively (P < 0.01). However, the time to progression showed no significant difference between the groups (P = 0.15).

CONCLUSION: ¹⁸F-FDG PET can be an important predictor of HCC treatment. In particular, the Tsuv_max/Lsuv_mean ratio (cutoff value of 1.90) can provide useful information in treatment prognosis for HCC patients treated with locoregional therapy.

Evaluation of biodistribution and antitumor effects of (188)Re-rhk5 in a mouse model of lung cancer

Targeting drugs to receptors involved in tumor angiogenesis is considered to be a novel and promising approach to improve cancer treatment. This study aimed to evaluate the anti-tumor efficacy of (188)Re-labeled recombinant human plasminogen kringle 5 ((188)Re‑rhk5) through [18F]-fluorodeoxyglucose (FDG) micro-positron emission tomography (PET). Radiolabeled rhk5 was obtained by conjugating the hystidine (6 x His) group at the carbon end of rhk5 with fac-[(188)Re(H(2)O)(3)(CO)(3)](+). The biodistribution study of (188)Re-rhk5 showed that (188)Re-rhk5 had a high initial tumor uptake and prolonged tumor retention. The highest tumor uptake of (188)Re-rhk5 (3.65±0.82% ID/g) was found 2 h after injection which decreased to 0.81±0.14% ID/g 12 h after injection. Following therapy, tumor size measurement indicated that (188)Re-rhk5-treated tumors were smaller than (188)Re-, rhk5- and saline-treated controls 6 days after the treatment. In vivo 18F-FDG micro-PET imaging showed significantly reduced tumor metabolism in the (188)Re-rhk5-treated mice vs. those treated with rhk5, (188)Re and saline control, 1 day after treatment. Moreover, the number of microvessels was significantly reduced after (188)Re-rhk5 treatment as determined by CD31 staining. Our results demonstrate that specific delivery of (188)Re-rhk5 allows preferential cytotoxicity to A549 lung cancer cells and tumor vasculature. (18)F-FDG micro-PET is a non-invasive imaging tool that can be utilized to assess early tumor responses to (188)Re-rhk5 therapy.

Metabolic restaging of hepatocellular carcinoma using whole-body F-FDG PET/CT

AIM

To evaluate the ability of (18)F-fluorodeoxyglucose positron emission and computed tomography ((18)F-FDG PET/CT) in restaging of hepatocellular carcinoma (HCC) after treatment.

METHODS

We reviewed a database of the diagnostic performance of (18)F-FDG PET/CT scan for patients with HCC following local or regional treatment. The database consisted of (18)F-FDG PET/CT information of 21 male and 4 female (age range, 27-81 years; mean age, 51.6 years) patients who had received surgical resection and/or interventional treatments and then underwent (18)F-FDG PET/CT scan. All patients had received enhanced CT scan of the liver two weeks before or after the (18)F-FDG PET/CT scan. Intrahepatic recurrence and/or extrahepatic metastases were confirmed by histological analysis or clinical and imaging follow-up. The accuracy of (18)F-FDG PET/CT study was determined by histopathological results or by clinical and imaging follow-up.

RESULTS

(18)F-FDG PET/CT was abnormal in 19 of the 25 (76.0%) patients. In detecting HCC recurrence, (18)F-FDG PET/CT scored 17 true positives, 5 true negatives, 2 false positives and 1 false negative. The sensitivity, specificity and accuracy of (18)F-FDG PET/CT in detecting HCC recurrence was 89.5%, 83.3% and 88%, respectively. (18)F-FDG PET/CT had an impact on management of these patients by settling the problem of an unexplained increase in alpha-fetoprotein after treatment (14 patients), by monitoring response to the treatment and guiding additional regional therapy (12 patients), by identifying extrahepatic metastases (10 patients), by identifying tumor growth or thrombosis in the portal vein (6 patients), or by guiding surgical resection of extrahepatic metastases (2 patients).

CONCLUSION

Our results suggest that whole body (18)F-FDG PET/CT may be useful in the early evaluation of residual, intrahepatic recurrent or extrahepatic metastatic lesions and able to provide valuable information for the management of HCC recurrence.

Effective inhibition of xenografts of hepatocellular carcinoma (HepG2) by rapamycin and bevacizumab in an intrahepatic model

PURPOSE

Hepatocellular carcinoma (HCC) displays a characteristic hypervascularity and depends on angiogenesis for tumor growth, which thus provides a potential target for therapeutic approaches to HCC. In this study, through the use of combined micro-positron emission tomography (PET)/computed tomography (CT), we investigate if such a combined targeting of vascular endothelial growth factor (VEGF) activity and expression might retard HCC growth in an orthotopic intrahepatic xenograft model.

PROCEDURES

Xenograft models were created by intraportal vein injection of HepG2 cell suspensions in severe combined immunodeficient mice. The mice were then treated with (1) rapamycin (RAPA), a mammalian target of rapamycin pathway inhibitor; (2) bevazicumab (BEV), a VEGF monoclonal antibody; and (3) a RAPA/BEV combination.

RESULTS

Assessment of HCC progression using CT with Omnipaque and PET with 2-deoxy-2-(F-18)-fluoro-D: -glucose showed that mice treated with RAPA/BEV had the lowest standardized uptake values (SUVs). At week 2, mice treated with RAPA/BEV, RAPA, and BEV all showed a marked decrease in the SUV(max) readings with the greatest drop being observed in the RAPA/BEV group (1.33 + 0.26, 1.81 + 0.2, 2.05 + 0.4 vs. vehicle control 2.11 + 0.53).

CONCLUSIONS

Our results, supported by micro-PET/CT, suggest that RAPA/BEV represents a potential novel antiangiogenic therapy for the treatment of HCC.

The current role of PET-CT in the characterization of hepatobiliary malignancies

BACKGROUND

Surgery has become heavily dependent on accurate imaging in the assessment and treatment of suspected or confirmed intra-abdominal malignancy. Positron emission tomography-computed tomography (PET-CT) fuses uptake of a radiotracer combined with CT images to assess both functional tissue activity and anatomical detail. Since its introduction it has offered new ways of treating gastrointestinal cancers.

METHODS

The review analyses the present literature regarding the use of PET-CT in the assessment, diagnosis, staging and treatment of hepatobiliary malignancies.

RESULTS

PET-CT is widely used in pre-operative tumours staging for colorectal liver metastases. There is convincing data that it may also be applicable for neuroendocrine tumours, assessment of indeterminate pancreas lesions and clinical drug trials. PET-CT is of limited value in hepatocellular cancers, although new techniques in dual-tracer PET-CT may change this.

CONCLUSION

Knowledge of the strengths and limitations of PET-CT is important for all surgeons managing cancer of the hepatobiliary system. More clinical data are required on PET-CT, particularly its effect on long-term survival in PET-CT-staged patients undergoing resection.

Review: Deoxyglucose compounds labeled with isotopes different from 18-fuoride: is there a future in clinical practice?

There are several radionuclide-labeled derivatives of deoxyglucose (DG) that have been developed including 2-fluro-deoxyglucose, ethylenedicysteine-deoxyglucose, diethylenetriaminepentaacetate-deoxyglucose, N-(2'-hydroxybenzyl)-2-amino-2-deoxy-D-glucose, and methyl D-glucoside that were synthesized and successfully labeled in high labeling fields. The former 4 were used for tumor imaging and methyl-D-glucoside for the diagnosis and the monitoring of the functional status of renal tubules. These derivatives are suitable for imaging examinations when labeled with either fluorine-18 (18F), technetium-99m (99mTc), carbon-11 (11C), or gallium-68 (68Ga). These compounds are suitable both for imaging and for therapy if labeled with rhenium-188 (188Re). In the area of molecular imaging of nuclear medicine, derivatives of radionuclide-labeled deoxyglucose will become an important tool for the diagnosis and carcinoma treatment in the clinic.

Highly metabolic thrombus of the portal vein: 18F fluorodeoxyglucose positron emission tomography/computer tomography demonstration and clinical significance in hepatocellular carcinoma

AIM: To assess the ability of ¹⁸F-fluorodeoxyglucose positron emission tomography/computer tomography (¹⁸F-FDG PET/CT) to differentiate between benign and malignant portal vein thrombosis in hepatocellular carcinoma (HCC) patients.

METHODS: Five consecutive patients who had HBV cirrhosis, biopsy-proven HCC, and thrombosis of the main portal vein and/or left/right portal vein on ultrasound (US), computer tomography (CT) or magnetic resonance imaging (MRI) were studied with ¹⁸F-FDG PET/CT. The presence or absence of a highly metabolic thrombus on ¹⁸F-FDG PET/CT was considered diagnostic for malignant or benign portal vein thrombosis, respectively. All patients were followed-up monthly with US, CT or MRI. Shrinkage of the thrombus or recanalization of the vessels on US, CT or MRI during follow-up was considered to be definitive evidence of the benign nature of the thrombosis, whereas enlargement of the thrombus, disruption of the vessel wall, and parenchymal infiltration over follow-up were considered to be consistent with malignancy. ¹⁸F-FDG PET/CT, and US, CT or MRI results were compared.

RESULTS: Follow-up (1 to 10 mo) showed signs of malignant thrombosis in 4 of the 5 patients. US, CT or MRI produced a true-positive result for malignancy in 4 of the patients, and a false-positive result in 1. ¹⁸F-FDG PET/CT showed a highly metabolic thrombus in 4 of the 5 patients. ¹⁸F-FDG PET/CT achieved a true-positive result in all 4 of these patients, and a true-negative result in the other patient. No false-positive result was observed using ¹⁸F-FDG PET/CT.

CONCLUSION: ¹⁸F-FDG PET/CT may be helpful in discriminating between benign and malignant portal vein thrombi. Patients may benefit from ¹⁸F-FDG PET/CT when portal vein thrombi can not be diagnosed exactly by US, CT or MRI.