Experimental Observation of Temperature Change Induced by Echo Train Length of Fast-Spin Echo at 3T MRI

This study aims to observe and estimate the temperature changes caused by the echo train lengths (ETLs) of fast-spin echo to ensure radiofrequency (RF)-related safety. RF-induced heating on ETL-stepped changes is evaluated using the proton resonance frequency shift (PRF) method and optic-fiber thermography (OFT). The increase in temperature caused by a clinical sequence was compared to that accumulated by the corresponding ETLs. The temperatures are similarly increased in ETLs from 10 to 30 (PRF: 0.109 ± 0.025 ℃, OFT: 0.079 ± 0.009 ℃), suggesting that a large number of ETLs could be utilized at practical sites. The RF-induced heating in the clinical setting (PRF: 0.775 ± 0.069 ℃, OFT: 0.510 ± 0.015 ℃) is comparable to the estimated temperature on the ETL-stepped changes (PRF: 0.780 ℃, OFT: 0.553 ℃). These enable accelerated acquisition with a large number of ETLs to be practically used and RF-induced safety to be thoroughly guaranteed.