Nonrigid correction of interleaving artefacts in pelvic MRI

Abstract

This paper presents a novel method to reduce the effects of interleaving motion artefacts in single-plane MR scanning of the pelvic region without the need for k-space information. Interleaved image (or multipacket) acquisition is frequently used to reduce cross-talk and scanning time during full pelvic MR scans. Patient motion during interleaved acquisition can result in non-linear "staircase" imaging artefacts which are most visible on sagittal and coronal reconstructions. These artefacts can affect the segmentation of organs, registration, and visualization. A fast method has been implemented to replace artefact affected slices in a packet with interpolated slices based on Penney et al (2004) whose method involves the registration of neighbouring slices to obtain correspondences, followed by linear interpolation of voxel intensities along the displacement fields. This interpolation method has been applied to correct motion affected MRI volumes by firstly creating a new volume where every axial slice from the artefact affected packet is removed and replaced with an interpolated slice and then secondly for each of these slices, 2D non-rigid registration is used to register each original axial slice back to its matching interpolated slice. Results show visible improvements in artefacts particularly in sagittal and coronal image reconstructions, and should result in improved intensity based non-rigid registration results between MR scans (for example for atlas based automatic segmentation). Further validation was performed on simulated interleaving artefacts which were applied to an artefact free volume. Results obtained on prostate cancer radiotherapy treatment planning contouring were inconclusive and require further investigation.

The Australian e‐Health Research Centre: enabling the health care information and communication technology revolution

“…While all projects aim to improve patients’ experience, two in particular — reducing waiting times at emergency departments through better resource planning, 17 and improving radiotherapy treatment for prostate 15 and brain cancer — fulfil this aim.…”

“…The MILXview platform is also being used to improve radiotherapy treatment planning for prostate cancer 15 and cancers of the brain. https://doi.org/10.5694/j.1326-5377.2011.tb02939.x describe an alternative treatment planning method for prostate cancer.…”

A magnetic resonance imaging‐based workflow for planning radiation therapy for prostate cancer

“…Probabilistic atlas‐based organ segmentation methods were developed to automatically segment the organs of interest (prostate, rectum, bladder, and femoral heads) from the MRI scans. After the scans were preprocessed (including correction of intensity inhomogeneity 8 and patient movement artefacts 9 ), the images and manually defined contours for each patient were combined into a single reference atlas by image registration methods. This atlas can then be warped onto the MRI scans of a new patient, automatically contouring the organs of interest (Box 3).…”

Motion correction of magnetic resonance imaging data by using adaptive moving least squares method

“…For instance, in two-packet MRI, all the even slices (termed 'even volume') are acquired first before the odd slices (termed 'odd volume') are obtained. Then the reconstructed MR images are vulnerable to motion artifacts due to subject movements during interleaved sequences [2]. This may result in mis-alignments among the acquired packets, which can be easily detected in sagittal and coronal views.…”

“…They used a Kaiser-Bessel function for interpolating missing data during the reconstruction process. Dowling et al [2] suggested the non-rigid correction of interleaving artifacts in pelvic MRI. Most of these methods have a similar algorithmic framework; in that they use registration for motion estimation.…”