Post-processing algorithm to correct field inhomogeneity in MR spectroscopy.
- Subvoxel field inhomogeneity correction enables CEST magnetic resonance imaging (MRI) Z-spectrum from body tissues where shimming is challenging.
- Intravoxel field inhomogeneity correction enables MR spectroscopy (MRS) and MR spectroscopy imaging (MRSI) in tissues experiencing magnetic field inhomogeneity.
MR spectroscopy (MRS) is a non-invasive technique to detect metabolic changes in the tissues of the human body. It has been used to assist in the diagnosis of diseases, such as cancer, epilepsy, Alzheimer’s diseases, and is often used as an advanced research tool. CEST is an MR technique that enables imaging of certain compounds at concentrations that are often too low to be imaged directly, such as glutamate and phosphocreatine. CEST MRI has been adopted in the clinical setting yet suffers from relatively low contrast. No algorithm overcomes the intravoxel inhomogeneity in spectroscopy (both routine MRS and CEST MRI spectroscopy).
Emory researcher, Dr. Sun, has developed a high-resolution field map-based deconvolution algorithm for correction of intravoxel field inhomogeneity in MR spectroscopy. Often, the field inhomogeneity within a single voxel cannot be corrected. Dr. Sun’s CEST intravoxel inhomogeneity correction (CIVIC) approach utilizes the high-resolution intravoxel inhomogeneity as an input to directly recover the original Z-spectrum in CEST MRI without field inhomogeneity. The algorithm also applies to conventional single-voxel MRS and multi-voxel MRS imaging. This technique may assist in capturing tissue close to tissue/air interface where field heterogeneity is common, as well as organs such as liver, cardiac, and breast, where shimming is challenging.
In vivo experiments have been demonstrated in glioma rat models.
Publication: Sun P.Z. (2019) Magn Reson Med, 83(4), 1348-1355.