Application value of three-dimensional visualization system in evaluating efficacy of microwave ablation in treatment of primary liver cancer

  Background   Local tumor progression (LTP) is a major problem in thermal ablation therapy for primary liver cancer. Treatment without reaching the safety ablation margin (SAM) is an important risk factor for LTP. The 3D visualization surgical system independently developed by our team can perform preoperative planning to assist ablation treatment, and it can also accurately and quantitatively evaluate the efficacy of tumor ablation through 3D reconstruction and registration fusion.

  Objective  To compare the accuracy of 3D visualization registration versus 2D enhanced MRI in evaluating the ablation efficacy of primary liver cancer, so as to verify the accuracy of 3D visualization registration in evaluating the ablation efficacy.

  Methods  Clinical data about 137 patients with ultrasound-guided ablation for primary liver cancer who admitted to the Department of Interventional Ultrasound of the First Medical Center of Chinese PLA General Hospital from June 2017 to June 2019 were retrospectively analyzed. The 3D visualization registration and 2D enhanced MRI were applied to evaluate the efficacy of tumor ablation pre-and postoperatively, and whether the tumor lesions were completely covered with the ablation lesions or the SAM was reached was analyzed. SAM referred to the area that exceeded 5mm of the primary tumor, which should be inactivated during ablation treatment. The ablation efficacy was divided into the following three grades according to SAM: A₀: SAM＞5 mm, A₁: 5 mm＞SAM＞0 mm, A₂: SAM＜0 mm, A₀ and A₁ represented complete tumor inactivation, and A₂ represented incomplete tumor inactivation. The 3D reconstruction and non-rigid registration fusion was applied in 3D visualization group, and image side-by-side contrast was applied in the 2D enhanced MRI group.

  Results  Ablation efficacy evaluated by 3D visualization showed A₀ in 91 cases, A₁ in 26 cases, A₂ in 20 cases; and the results evaluated by 2D enhanced MRI showed A₀ in 109 cases, A₁ in 17 cases, A₂ in 11 cases, with significant difference between the two methods (P=0.041). The follow-up results showed that LTP occurred in 22 patients, and these patients were evaluated as 2 cases in A₁ category and 20 cases in A₂ category by the 3D visualization ; and 11 cases in A₁ category and 11 cases in A₂ category by the 2D enhanced MRI (P=0.003). The 3D visualization was superior to 2D enhanced MRI in terms of diagnostic accuracy (98.5% vs 92.0), sensitivity (90.9% vs 50.0%), and negative predictive value (98.3% vs 90.6%) (all P＜0.05). Both of the two methods achieved 100% in specificity and positive predictive value.

  Conclusion  3D visualization technology has high sensitivity for the evaluation of ablation efficacy. Compared with 2D enhanced MRI, 3D visualization technology evaluate the tumor ablation efficacy more accurately and quantitatively, and has a higher predictive value for LTP.