Peritumoral abnormalities on dynamic-enhanced CT after brachytherapy for hepatic malignancies: local progression or
Guanyu Chen1, Dechao Jiao2, Sheng Peng3
1Department of Minimally Invasive & Interventional Radiology, State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, Guangdong, 510060, People's Republic of China.
Objectives:
To determine if dynamic CT can differentiate local progression from radioactive seed-induced peritumoral reaction (RSIPR) after brachytherapy with iodine-125 radioactive seeds (BIRS) for advanced hepatic malignancies.
Methods:
Enhanced CT images of seed-implanted lesions between 2006 and 2018 were retrospectively evaluated. Hounsfield units of peritumoral parenchyma were measured and assessed quantitatively. The classification, conversion, consequences, and serological indicators during follow-up were recorded and quantified. Statistical differences were analyzed using a Pearson χ2 test.
Results:
RSIPR was observed in 201 of 290 (69.3%) lesions (161 patients; median age, 55 years; range, 26-79 years), while local progression occurred in 53 lesions. The low density of local progression was much lower than that of RSIPR (p < 0.001), and the former did not exhibit iso-/high density in the portal or equilibrium phase. Ring-like enhancement in progressive lesions was also quite different from RSIPR. Local progression rate was lower for lesions with RSIPR than for those without RSIPR (14.9% vs 25.8%; p = 0.03), and their doses were different (397.2 Gy vs 120.3 Gy, p < 0.001).
Conclusions:
Radioactive seed-induced peritumoral reaction has characteristic manifestations on CT images, which is associated with a higher dose of lesions and lower local progression rate. Notably, the enhancement pattern of local progression was distinct from RSIPR and was clearly distinguishable on dynamic-enhanced CT.
Key Points:
• Radioactive seed-induced peritumoral reaction after brachytherapy with 125I seeds for liver malignancies has characteristic manifestations on CT images, which is associated with a higher dose of lesions (397.2 Gy vs 120.3 Gy, p < 0.001), as a focal radiation injury. • Lesions with RSIPR were less likely to develop local progression, while those without RSIPR had a higher rate of local progression (14.9% vs 25.8%; p = 0.03). • The enhancement pattern of local progression after brachytherapy was distinct from radioactive seed-induced peritumoral reaction and was clearly distinguishable on dynamic-enhanced CT.
