PET/CT valuable for distinguishing benign from malignant portal vein thrombosis in liver cirrhosis

The study, published in the Egyptian Journal of Radiology and Nuclear Medicine, showed that FDG radiotracer uptake on patient F-18 FDG-PET/CT scans was greater when portal vein thrombi were tumours than benign ("bland") thrombi.

"Tumour thrombosis diagnosis and its differentiation from benign thrombosis are critical for managing patients, planning treatments, and minimizing unneeded anticoagulation therapy," Sameh Abokoura, Menoufia University, Shebin Elkoum, Menoufia, Egypt, and colleagues wrote in their study.

Portal vein thrombosis is the complete or partial obstruction of blood flow in the portal vein to the liver due to a thrombus presence. Bland thrombi occur in cancer and non-cancer patients; tumour thrombi and bland can coexist. 18F-FDG PET/CT (18F-fluorodeoxyglucose positron emission tomography/computed tomography) is useful in detecting and diagnosing thrombosis and differentiating it from benign thrombosis.

Abokoura and colleagues aimed to evaluate the value of 18F-FDG PET/CT in distinguishing benign from malignant portal vein thrombosis in patients with liver cirrhosis.

For this purpose, the researchers analyzed 38 patients with liver cirrhosis and portal vein thrombosis, either with or without malignant hepatic tumours, who underwent F-18 FDG-PET/CT scans at their hospital in Menoufia between 2021 and 2022. The semiqualitative analysis included data on all patients' FDG tracer maximum standard uptake (SUVmax) values.

The authors reported the following findings:

• The SUVmax values were significantly higher in the tumour thrombosis group (6.26 ± 1.94) compared to the bland thrombosis group (1.79 ± 0.69).
• The ROC curve of semiqualitative analysis (SUVmax) revealed a specificity of 36.4% and sensitivity of 96.3% at the area under curve of 0.827 with SUVmax > 3.5 as the pathological cut-off value to distinguish tumour from bland thrombi.

The group noted while portal vein thrombosis is frequently associated with liver cirrhosis, it may also occur in patients with cancer, pancreatitis, abdominal sepsis, systemic lupus erythematosus, or other conditions involving hypercoagulable states.

"using semiqualitative analysis, 18F-FDG PET/CT is a valuable new technique in differentiating neoplastic from bland PV thrombi, with optimal cut-off SUVmax value > 3.5 as a criterion," Abokoura and the team concluded.

The limitation of the study was that in 7 cases, imaging and clinical findings were used first to determine the thrombosis type rather than histopathological evidence. Also, the study had flaws due to the retrospective study design and the relatively small patients' number included.

Reference:

Abokoura, S., Ellaban, H. S., & Aly, R. A. (2023). The role of 18F-FDG PET/CT in distinguishing benign from malignant portal vein thrombosis. Egyptian Journal of Radiology and Nuclear Medicine, 54(1), 1-10. https://doi.org/10.1186/s43055-023-01058-1