Fast spectroscopic imaging for non-invasive thermometry using the Pr[MOE-DO3A] complex.
The praseodymium complex of 10-(2-methoxyethyl)-1,4,7,10-tetraaza-cyclododecane-1,4,7-tr iacetate) was evaluated as a temperature-sensitive contrast agent using the temperature dependence (approximately 0.12 ppm degrees C(-1)) of the chemical shift of its methoxy side group signal. Pr[MOE-DO3A] was employed in combination with spectroscopic imaging (SI) methods for the determination of spatially resolved 2D and 3D temperature distributions in phantoms. Conventional SI and fast echo planar SI sequences (EPSI) were implemented on a 4.7 T MR imaging system fulfilling the demands for non-invasive thermometry (NIT) with respect to thermal and temporal resolution, being <1 degree C and <20 s total measuring time, respectively. The sequences are based on a fast spin echo SI method taking into account the very short relaxation times of the Pr complex methoxy group (T1 = 28 ms, T2 = 13 ms) and its chemical shift difference (-24 ppm) from water. Calibration curves were measured in a uniformly heated water phantom and 2D SI methods were applied to dynamic heating experiments. The average differences between the temperatures measured via fibreoptic thermometer and those derived from the spectroscopic methods were < or =0.2 degrees C. Furthermore, 3D EPSI experiments with a 16 x 16 x 16 matrix size yielded temperature measurements within 17 s from voxels of size 3 x 3 x 3 mm3.
Hentschel
M
M
Department of Radiology, Charité, Medical School of the Humboldt University, Berlin, Germany. michael.hentschel@charite.de
Dreher
W
W
Wust
P
P
Röll
S
S
Leibfritz
D
D
Felix
R
R
D002138:Calibration; D003287:Contrast Media; D005336:Fiber Optic Technology; D006801:Humans; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds; D019047:Phantoms, Imaging; D011221:Praseodymium; D013817:Thermography / Q000295:instrumentation / Q000379:methods*
D003287:Contrast Media; D009942:Organometallic Compounds; C100694:praseodymium-2-methoxyethyl DO3A; D011221:Praseodymium