[Research on thermal dose for high intensity focused ultrasound treatment based on the temperature-map of magnetic resonance imaging].
Based on the T-map of MRI, this research sought to address the relationship between the simulated threshold thermal dose of coagulation and actual the coagulation on histological slides. The MR imaging guided HIFU system was used, the parameters of therapeutic transducer were: frequency--1 MHz, diameter--150 mm, and focal length--150 mm. In fresh beef liver tissue in vitro, sonications were delivered at a fixed depth of 20 mm and at varying powers. The temperature-sensitive MR images obtained during the sonications were used to estimate the temperature, and the thermal dosage of each voxel in the target region was calculated. The thermal dosage of each voxel was compared with the reference threshold thermal dosage, so as to calculate the boundary and area of the coagulated tissue. After the exposure, the tissue was dissected along the maximal section of the coagulation necrosis, and the area of the biological focal region was measured.


RESULTS
The occurrence of tissue damage correlated well with the equivalent thermal dose calculation based on the T-mapping of MRI, and they share the same variation tendency.


CONCLUSIONS
The equivalent thermal dose calculation based on the T-Map of MRI correlates well with the actual tissue damage, and so an index to predict the threshold for tissue damage in vivo is provided. This index offers improved online control over minimally invasive thermal treatments and increases the security of the therapy.
Liu
Lili
L
Department of Biomedical Engineering, Key Laboratory of Ultrasonic Medicine Engineering, Chongqing Medical University, Chongqing 400016, China.
Li
Faqi
F
Gong
Xiaobo
X
Liu
Yingjiang
Y
Hu
Xiao
X
D000818:Animals; D002417:Cattle; D004307:Dose-Response Relationship, Radiation; D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation / Q000379:methods*; D006358:Hot Temperature / Q000627:therapeutic use*; D066298:In Vitro Techniques; D008099:Liver / Q000528:radiation effects*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011829:Radiation Dosage; D013696:Temperature; D013813:Therapy, Computer-Assisted / Q000379:methods*; D013817:Thermography / Q000379:methods; D014464:Ultrasonic Therapy / Q000379:methods