Patient-Specific Prediction of Immediate Phase Lung Microwave Ablation Zone Size.

PURPOSE: To investigate the effect of patient and tumor-specific characteristics on the size of immediate phase lung microwave ablation (MWA) zone and establish a prediction model.

METHODS AND MATERIALS: This IRB-approved, HIPAA compliant cohort included 164 lesions from 99 patients who underwent CT-guided lung MWA and the two-dimensional elliptical ground-glass opacity ablation zone was measured. Duration, maximum temperature, tumor depth, presence of emphysema, history of ipsilateral lung ablation, surgery, and radiation were recorded. K-fold cross validation with k=5 and Least Absolute Shrinkage and Selection Operator were used to build prediction models for the major and minor axes, and area of the ablation zone.

RESULTS: The median of immediate phase ablation duration was 2 minutes (IQR: 1.5 - 4.25) with 65W of power for all ablations. The mean major, minor axes, and area of ablation zone were 3.1±0.6cm, 2.0±0.5cm, and 5.1±2.1cm2 . The major axis, minor axis, and area of immediate phase ablation zone dimensions were significantly associated with duration (p<0.001, p<0.001, p<0.001), maximum temperature (p<0.001, p<0.001, p<0.001), tumor depth (p=0.387, p<0.001, p<0.001), history of ipsilateral lung ablation (p=0.008, p=0.286, p=0.076), and lung radiation (p=0.001, p=0.042, p=0.015). The prediction model showed R2 values for major and minor axes and area of the ablation zone to be 0.50, 0.45, and 0.53, respectively.

CONCLUSION: Duration, maximum temperature, tumor depth, history of ipsilateral lung ablation, surgery, and radiation were significantly associated with the ablation zone dimensions and size and can be used to build the prediction model to approximate the immediate phase lung MWA zone.