3D Proton Resonance Frequency Shift MR Thermometry for Monitoring Clinical Microwave Ablation: Comparison of Stack-of-Stars and Stack-of-Spirals Sequences

Microwave ablation (MWA) of hepatic tumors benefits from MR thermometry, enabling real-time temperature monitoring to guide treatment and protect healthy tissue. However, MR thermometry in the abdomen is challenging due to respiratory and intestinal motion. This study evaluates two advanced 3D imaging sequences, Stack-of-Stars (Stars) and Stack-of-Spirals (Spirals), for precise MWA thermometry in phantom and volunteer experiments. Spirals demonstrated superior temperature precision, with a standard deviation of 0.78 ± 0.05°C in unheated regions, compared to 2.92 ± 0.26°C for Stars. In heated regions, Spirals achieved a lower RMSE (0.5 ± 0.1°C vs. 1.2 ± 0.2°C for Stars) and a higher Dice score for ablation zone delineation (0.89 ± 0.01 vs. 0.76 ± 0.10). Spirals also produced sharper images with fewer artifacts under simulated respiratory motion, while Stars showed streaking artifacts due to higher undersampling. These findings highlight Spirals’ potential for accurate real-time thermometry in liver ablation. Future work should focus on improving reconstruction speed and mitigating susceptibility artifacts to enable clinical applications.