Search

Proton resonance frequency shift (PRFS) is an MRI-based simple temperature mapping method that exhibits higher spatial and temporal resolution than temperature mapping methods based on T1 relaxation time and diffusion. PRFS temperature measurements are validated against fiber-optic thermal sensors (FOSs). However, the use of FOSs may introduce temperature errors, leading to both underestimation and overestimation of PRFS measurements, primarily due to material susceptibility changes caused by the thermal sensors. In this study, we demonstrated susceptibility-corrected PRFS (scPRFS) with a high frame rate and accuracy for suitably distributed temperatures. A single-echo-based background removal technique was employed for phase variation correction, primarily owing to magnetic susceptibility, which enabled fast temperature mapping. The scPRFS was used to validate the temperature fidelity by comparing the temperatures of fiber-optic sensors and conventional PRFS through phantom-mimicked human and ex vivo experiments. This study demonstrates that scPRFS measurements in agar-gel are in good agreement with the thermal sensor readings, with a root mean square error (RMSE) of 0.33–0.36 °C in the phantom model and 0.12–0.16 °C in the ex vivo experiment. These results highlight the potential of scPRFS for precise thermal monitoring and ablation in both low- and high-temperature non-invasive therapies. [ABSTRACT FROM AUTHOR]

Proton resonance frequency shift (PRFS) is an MRI-based simple temperature mapping method that exhibits higher spatial and temporal resolution than temperature mapping methods based on T1 relaxation time and diffusion. PRFS temperature measurements are validated against fiber-optic thermal sensors (FOSs). However, the use of FOSs may introduce temperature errors, leading to both underestimation and overestimation of PRFS measurements, primarily due to material susceptibility changes caused by the thermal sensors. In this study, we demonstrated susceptibility-corrected PRFS (scPRFS) with a high frame rate and accuracy for suitably distributed temperatures. A single-echo-based background removal technique was employed for phase variation correction, primarily owing to magnetic susceptibility, which enabled fast temperature mapping. The scPRFS was used to validate the temperature fidelity by comparing the temperatures of fiber-optic sensors and conventional PRFS through phantom-mimicked human and ex vivo experiments. This study demonstrates that scPRFS measurements in agar-gel are in good agreement with the thermal sensor readings, with a root mean square error (RMSE) of 0.33–0.36 °C in the phantom model and 0.12–0.16 °C in the ex vivo experiment. These results highlight the potential of scPRFS for precise thermal monitoring and ablation in both low- and high-temperature non-invasive therapies.

[Display omitted] • A novel rapid thermal shock method was adopted to achieve the fast preparation of nitrogen-doped graphene film within 10 s. • The NG film prepared through rapid thermal shock method has a high content of nitrogen element, among which the content of graphite nitrogen reaches more than 60%. • Thanks to the presence of numerous graphite nitrogen in NG, the electrical conductivity and the Seebeck coeffience of NG films improve a lot. Meanwhile, the introduction of N element also causes the thermal conductivity of the NG film to decline precipitatingly, according to the calculation results of desity function theory. • A novel temperature sensor was fabricated based the NG film, it is found that the device has good accuracy at both room temperature and high temperature (more than 600 ℃), and shows excellent sensitivity temperature changes. Graphene is restricted by its zero-band gap when applying in functional components. However, its band structure can be adjusted appropriately through nitrogen doping. At present, many nitrogen doping processes have been developed such as chemical vapor deposition, thermal annealing and plasma sputtering, but in general these methods are time-consuming and difficult to control the type of nitrogen atom doped. In this work, an in situ high-temperature thermal shock process, with an extremely fast rate of temperature change of more than 104 K/s, is developed and used to prepare the nitrogen doped graphene (NG) films. This novel N-doped process enables the preparation of NG films within 10 s, which is the fastest to the best of our knowledge. Moreover, the type and content of doped nitrogen atoms can be effectively regulated by controlling the composition of precursor films. Optimally, the nitrogen content of NG film reaches 2.26 %, and the proportion of graphite nitrogen is more than 60 %. The electrical conductivity and the average Seebeck coefficient of the NG film are 13,870 S·m−1 and −46.5 μV/K, respectively. Its thermoelectric power factor reaches 30 μW·m−1·K−1, indicating that the NG film has a good prospect of functional application. Furtherly, A NG film-based temperature reading device is developed, which shows ultra-high accuracy and sensitivity in temperature reading within a rather wide temperature range. [ABSTRACT FROM AUTHOR]