The Potential for Absolute Temperature Imaging Based on Brain Metabolites Using an FID-Shifting Approach in Gradient...

Area of Science:

• Magnetic Resonance Imaging
• Spectroscopy
• Thermodynamics

Background:

• Accurate temperature measurement is crucial in various scientific fields.
• Magnetic resonance (MR) techniques offer non-invasive temperature mapping capabilities.
• Echo planar spectroscopic imaging (EPSI) is a rapid MR imaging technique.

Purpose of the Study:

• To develop and assess an efficient gradient echo implementation of EPSI (GREPSI) for absolute temperature measurement.
• To evaluate the accuracy and precision of GREPSI for temperature mapping.
• To demonstrate the feasibility of GREPSI for in vivo temperature imaging.

Main Methods:

• Utilized a GREPSI sequence with oscillating readout gradients and continuous signal readout.
• Employed a novel free induction decay (FID) time shifting method to separate metabolite signals from water.
• Acquired data on a brain phantom at various temperatures and compared with single voxel spectroscopy (SVS) and chemical shift imaging (CSI).
• Performed in vivo scans on a healthy volunteer.

Main Results:

• The FID shifting method effectively removed water signals, enabling metabolite peak identification.
• GREPSI demonstrated high accuracy (within 2% at 42°C) and precision (0.2°C) for absolute temperature measurements.
• Temperature measurements were independent of water suppression, with a standard deviation of 0.31°C at room temperature.
• In vivo temperature images of a healthy volunteer were within the expected normal range.

Conclusions:

• GREPSI provides an efficient and accurate method for absolute temperature measurement.
• The technique allows for precise temperature mapping in scan times of 2-5 minutes for an 8-slice slab.
• GREPSI shows promise for non-invasive temperature monitoring in biological and medical applications.