Abstract
Purpose:
To provide quantitative temperature monitoring for thermal therapies in bone marrow by measuring temperature‐dependent signal changes in the bone marrow of ex vivo canine femurs heated with a 980‐nm laser at 1.5T and 3.0T.
Materials and Methods:
Using a multi‐gradient echo (≤16) acquisition and signal modeling with the Stieglitz–McBride algorithm, the temperature sensitivity coefficients (TSC, ppm/°C) of water and multiple lipid components' proton resonance frequency (PRF) values are measured at high spatiotemporal resolutions (1.6 × 1.6 × 4 mm^3^, ≤5 seconds). Responses in R~2~* and amplitudes of each peak were also measured as a function of temperature simultaneously.
Results:
Calibrations demonstrate that lipid signal may be used to compensate for B~0~ errors to provide accurate temperature readings (<1.0°C). Over a temperature range of 17.2–57.2°C, the TSCs after correction to a bulk methylene reference are −0.87 × 10^−2^ ± 4.7 × 10^−4^ ppm/°C and −0.87 × 10^−2^ ± 4.0 × 10^−4^ ppm/°C for 1.5T and 3.0T, respectively.
Conclusion:
Overall, we demonstrate that accurate and precise temperature measurements can be made in bone marrow. In addition, the relationship of R~2~* and signal amplitudes with respect to temperature are shown to differ significantly where conformal changes are predicted by Arrhenius rate model analysis. J. Magn. Reson. Imaging 2011;33:1128–1135. © 2011 Wiley‐Liss, Inc.