Aim: This article reports on the use of magnetic resonance imaging to access the post-interventional necrosis volume of liver metastases immediately after and 48 hours after LITT.
Material and methods: In this prospective study, 56 liver metastases from 39 patients (16 females, 23 males, mean age 60.4 years) underwent LITT. The 56 metastases were divided into 4 groups according to the ablation strategy (dependent on multi-applicator technique and laser duration). Groups I and II were treated with an applicator and a time of ablation greater than 15 minutes and 20 minutes, respectively. In groups III and IV the multi-applicator technology with 3 or 4 applicators and a constant ablation time of 20 minutes were used. With the help of heightened contrast MRI of the liver, the portrayal of the post-interventional necrosis was conducted immediately after LITT and 48 hours after LITT. The post-interventional controls after 48 hours were performed during the inpatient stay. The protocol was complemented by an outpatient long-term control after more than 3 months.
Results: The local tumor control rate was initially 96.4%. After 3 months it decreased to 92.1%. The mean necrosis volume directly after LITT was: Group I (n = 11; 1 applicator, 30 watt, 10-15 minutes) 6.69 cm(3); Group II (n = 13; 1 applicator, 30 watt, 20 minutes) 10.95 cm(3); Group III (n = 28; 2 applicator, 30 watt, 10-15 minutes) 21.47 cm(3); Group IV (n = 4; 3 applicator, 30 watt, 20 minutes) 40.20 cm(3). In comparison, the necrosis volume after 48 hours increased: Group I 10.56 cm(3); Group II 15.11 cm(3); Group III 31.33 cm(3), Group IV 55.73 cm(3)).
Conclusion: After 48 hours a progressive increase of post-interventional necrosis volumes compared to volumes directly after LITT was able to be observed. An MRI control after 48 hours, as opposed to an MRI control directly after intervention, is a better indicator for post-interventional success after LITT.