Automatic voxel positioning for single voxel spectroscopy

Abstract

During the typical acquisition of single-voxel Magnetic Resonance Spectroscopy (MRS), MR technologists select the corresponding voxel-of-interest (VOI) manually, which induces some degree of variability. Several automatic VOI positioning methods using rigid registration have been proposed to address the issue for longitudinal scans of the same subject.

This approach can be generalized to multi-subject scans, by utilizing non-rigid registrations such as affine and non-linear to accommodate anatomical variability. In this paper, we present the implementation and outcome of a scheme for automatic voxel placement in single-voxel spectroscopy using non-linear registration. The scheme is based on transfer of voxels prescribed on an atlas to the subject images during the scanning session and allows fast and reliable inter-subject placement of voxels for spectroscopy measurements.

We have performed validations of our proposed method using the datasets from several previously published studies. In addition, 1H spectra of various volumes of interest (VOIs) from multiple subjects were measured with the Siemens 3T scanner at KAIST as well as multiple Siemens and Philips scanners in the United States using the proposed automated VOI placements to validate the performance across different environments. MRS data acquired using automatic placement produced spectral quality comparable to manual placement, while yielding equivalent or superior intra- and inter-subject spatial consistency over manual placement.