Magnetic resonance (MR) thermometry is a noninvasive method for monitoring local temperature change during thermal therapy. In this study, a MR temperature analysis program was established for a laser with gold nanorods (GNRs) and high-intensity focused ultrasound (HIFU)-induced heating MR thermometry. The MR temperature map was reconstructed using the water proton resonance frequency (PRF) method. The temperature-sensitive phase difference was acquired by using complex number subtraction instead of direct phase subtraction in order to avoid another phase unwrapping process. A temperature map-analyzing program was developed and implemented in IDL (Interactive Data Language) for effective temperature monitoring. This one program was applied to two different heating devices at a clinical MR scanner. All images were acquired with the fast spoiled gradient echo (fSPGR) pulse sequence on a 3.0 T GE Discovery MR750 scanner with an 8-channel knee array coil or with a home-built small surface coil. The analyzed temperature values were confirmed by using values simultaneously measured with an optical temperature probe (R2 = 0.996). The temperature change in small samples induced by a laser or by HIFU was analyzed by using a raw data, that consisted of complex numbers. This study shows that our MR thermometry analysis program can be used for thermal therapy study with a laser or HIFU at a clinical MR scanner. It can also be applied to temperature monitoring for any other thermal therapy based on the PRF method.
Bibliographical noteFunding Information:
We would like to thank Drs. Jaemoon Yang and Yoochan Hong for providing the GNRs. We would also like to thank Itay Rachmilevitch and Kyeyong Kang (In-Sightec) for technical support with the HIFU system. This work was supported by a grant from the National Research Foundation of Korea (NRF) funded by the Korean government’s Ministry of Education and Science Technology (MEST, 2012R1A2A1A01011328).
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)