A precise and fast temperature mapping using water proton chemical shift

TLDR

A new temperature measurement procedure using phase mapping was developed that exploits the temperature dependence of the water proton chemical shift. The method uses phase mapping of the water proton chemical shift, but temperature measurement error is influenced by B0 shifts from sample position changes, blood flow, and other factors, with position shift being the most serious. Highly accurate and fast measurements were obtained in phantom and in vivo experiments, achieving accuracy better than ±0.5 °C in a pure water phantom within seconds per slice, similar accuracy for tissues with comparable composition, and ±1 °C accuracy with 0.6 × 0.6 mm resolution in a cat brain.

Abstract

A new temperature measurement procedure using phase mapping was developed that makes use of the temperature dependence of the water proton chemical shift. Highly accurate and fast measurements were obtained during phantom and in vivo experiments. In the pure water phantom experiments, an accuracy of more than +/- 0.5 degrees C was obtained within a few seconds/slice using a field echo pulse sequence (TR/TE = 115/13 ms, matrix = 128 x 128, number of slices = 5). The temperature dependence of the water proton chemical shift was found to be almost the same for different materials with a chemical composition similar to living tissues (water, glucide, protein). Using this method, the temperature change inside a cat's brain was obtained with an accuracy of more than +/- 1 degree C and an in-plane resolution of 0.6 x 0.6 mm. The temperature measurement error was affected by several factors in the living system (B0 shifts caused by position shifts of the sample, blood flow, etc.), the position shift effect being the most serious.