Fluoromethylcholine PET in recurrent multifocal hepatoma

Incidental Finding on 11C-Choline-PET/CT of Hepatocellular Carcinoma Recurrence in a Prostate Cancer Patient With Negative Abdominal CT Scan

A 76-year-old man, who experienced prostate cancer biochemical relapse after 12 years from radical prostatectomy, underwent abdominal CT scan for restaging purposes, negative for metastases, and then C-choline PET/CT. The only finding was an area of focal uptake of radiotracer between the intestinal loops and the abdominal wall; after resection, the lesion demonstrated to be a metastasis from hepatocellular carcinoma (HCC), for which the patient had undergone liver resection 2 years earlier. This case proves that abnormal foci of C-choline uptake in the peritoneum in HCC patients have to be kept in mind as possible sites of HCC-metastases.

Arterial Phase 18F-Fluorocholine PET/CT in Hepatocellular Carcinoma

A 57-year-old man was referred to our institution for F-fluorocholine PET/CT to characterize a pulmonary nodule in a context of hepatocellular carcinoma. F-FDG PET/CT did not show any uptake of the pulmonary nodule. F-fluorocholine PET/CT showed high uptake of the pulmonary nodule, confirming its metastatic origin. Furthermore, liver early dynamic acquisitions allowed better visualization of the hepatocellular carcinoma during the "arterial phase" than at equilibrium.

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

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

Detection of hepatocellular carcinoma with PET/CT: a prospective comparison of 18F-fluorocholine and 18F-FDG in patients with cirrhosis or chronic liver disease

This prospective study aimed to compare the diagnostic performance of (18)F-fluorocholine and (18)F-FDG for detecting and staging hepatocellular carcinoma (HCC) in patients with chronic liver disease and suspected liver nodules.

METHODS

Whole-body PET/CT was performed in a random order at 10 min after injection of 4 MBq of (18)F-fluorocholine per kilogram and at 1 h after injection of 5 MBq of (18)F-FDG per kilogram. PET/CT results were read in a masked manner by 2 specialists, and diagnostic performance was assessed from the results of consensus masked reading. Those focal lesions appearing with increased or decreased activity, compared with background, on (18)F-fluorocholine PET/CT were considered positive for malignancy. The standard of truth was determined on a per-site basis using data from a histologic examination and a follow-up period of more than 6 mo; on a per-patient basis, the Barcelona criteria were also accepted as a proof of HCC in 5 patients.

RESULTS

Eighty-one patients were recruited; standard of truth was determined in 59 cases. HCC was diagnosed in 34 patients. Therefore, sensitivity was 88% for (18)F-fluorocholine and 68% for (18)F-FDG (P = 0.07), and in 70 sites, sensitivity was 84% for (18)F-fluorocholine, significantly better than the 67% for (18)F-FDG (P = 0.01). Of the 11 patients with well-differentiated HCC, 6 had a positive result with (18)F-fluorocholine alone, whereas (18)F-FDG was never positive alone; corresponding site-based sensitivity was 94% for (18)F-fluorocholine and 59% for (18)F-FDG (P = 0.001). The detection rate of 18 sites corresponding to other malignancies was 78% for (18)F-fluorocholine and 89% for (18)F-FDG. In nonmalignant sites, (18)F-fluorocholine appeared less specific than (18)F-FDG (62% vs. 91% P < 0.01) because of uptake by focal nodular hyperplasia.

CONCLUSION

(18)F-fluorocholine was significantly more sensitive than (18)F-FDG at detecting HCC, in particular in well-differentiated forms. In contrast, (18)F-FDG appeared somewhat more sensitive at detecting other malignancies and was negative in focal nodular hyperplasia. Thus (18)F-fluorocholine appears to be a useful PET/CT tracer for the detection and surveillance of HCC; however, performing PET/CT with both radiopharmaceuticals seems to be the best option.

Transport and metabolism of radiolabeled choline in hepatocellular carcinoma

Altered choline (Cho) metabolism in cancerous cells can be used as a basis for molecular imaging with PET using radiolabeled Cho. In this study, the metabolism of tracer Cho was investigated in a woodchuck hepatocellular carcinoma (HCC) cell line (WCH17) and in freshly derived rat hepatocytes. The transporter responsible for [(11)C]-Cho uptake in HCC was also characterized in WCH17 cells. The study helped to define the specific mechanisms responsible for radio-Cho uptake seen on the PET images of primary liver cancer such as HCC. Cells were pulsed with [(14)C]-Cho for 5 min and chased for varying durations in cold media to simulate the rapid circulation and clearance of [(11)C]-Cho. Radioactive metabolites were extracted and analyzed by radio-HPLC and radio-TLC. The Cho transporter (ChoT) was characterized in WCH17 cells. WCH17 cells showed higher (14)C uptake than rat primary hepatocytes. [(14)C]-Phosphocholine (PC) was the major metabolite in WCH17. In contrast, the intracellular Cho in primary hepatocytes was found to be oxidized to betaine (partially released into media) and, to a lesser degree, phosphorylated to PC. [(14)C]-Cho uptake by WCH17 cells was found to have both facilitative transport and nonfacilitative diffusion components. The facilitative transport was characterized by Na(+) dependence and low affinity (K(m) = 28.59 ± 6.75 μM) with partial energy dependence. In contrast, ChoT in primary hepatocytes is Na(+) independent and low affinity. Our data suggest that transport and phosphorylation of Cho are responsible for the tracer accumulation during [(11)C]-Cho PET imaging of HCC. WCH17 cells incorporate [(14)C]-Cho preferentially into PC. Conversion of [(14)C]-PC into phosphatidylcholine occurred slowly in vitro. Basal oxidation and phosphorylation activities in surrounding hepatic tissue contribute to the background seen in [(11)C]-Cho PET images.