OBJECTIVES: In MR-guided HIFU ablation, the accuracy of temperature measurement was direct proportion to the signal-to-noise (SNR) ratio of the MRI image. In this study, an MRI receive-only surface coil was fabricated and used to provide higher SNR MRI signal, where was around the hot spot, to improve the accuracy of MRI temperature measurement of HIFU ablation in a mini-pig model. METHODS: A movable hole-circle surface coils with 14cm diameter of wire loop was fabricated and mounted onto the HIFU transducer package. The dynamic temperature images during HIFU ablation of porcine meat and living mini-pig leg were measured by this home-made surface coils. MR temperature measurements were made based on proton resonance frequency (PRF) shift method. A spoiled gradient echo sequence was applied for temperature mapping in a 1.5 Tesla MRI scanner (TR = 13ms, TE = 7 ms, flip angle = 30 deg, matrix 128x128, FOV= 256 x 256 mm, slice thickness = 8 mm). RESULTS: The standard deviations of temperature measured by the 14cm diameter circle surface coils were 0.3, 0.6 deg C for porcine meat and pig leg, respectively. CONCLUSIONS: The results of the experiments showed that the signal-to-noise ratio would be improved and the higher precision of the temperature measurement could be obtained. It showed the advantage and feasibility of using a smaller and mobile surface coil for MR-guided HIFU ablation.
Date:
2013-05
Relation:
13th International Symposium on Therapeutic Ultrasound. 2013 May;167.
