Intradiscal temperature monitoring using double gradient-echo pulse sequences at 1.0T.
OBJECTIVE
To validate an unspoiled gradient-recalled echo pulse sequence with dual echo acquisition as a means to increase temperature sensitivity while monitoring intradiscal laser ablation therapy.


METHODS
Phantom experiments as well as in vitro thermal ablation simulations were performed in an open 1.0T magnetic resonance (MR) scanner. Three methods of noninvasive MR-thermometry based on the signal void decrease caused by T1-relaxation time increase (T1), the temperature-dependent proton resonance frequency (PRF) shift, and a combination of both methods with complex differences (CD) were compared. Temperature accuracy and reliability of temperature distribution were the main assessment criteria.


RESULTS
The optimum temperature sensitivity was found using CD in phantom experiments. During in vitro experiments the PRF showed the smallest margin of error (T1: +/-1.64 degrees C, PRF: +/-1.23 degrees C, CD: +/-1.29 degrees C) and the best qualitative evaluation of temperature.


CONCLUSIONS
Intradiscal temperature monitoring with an unspoiled dual-echo sequence is most accurate with PRF-thermometry in combination with the long echo time. Magnitude images with an initial short echo time permit high image detail of the heat-induced lesion.
Institut für Radiologie, Charité, Universitätsmedizin Berlin, Germany. uta.wonneberger@charite.de
Uta
U
Wonneberger
Bernhard
B
Schnackenburg
Waldemar
W
Wlodarczyk
Thula
T
Walter
Florian
F
Streitparth
Jens
J
Rump
Ulf K M
UK
Teichgräber
D000465:Algorithms; D001831:Body Temperature; D002138:Calibration; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D011522:Protons; D015203:Reproducibility of Results; D013696:Temperature
D011522:Protons