Abstract
Background and purposeThe superior soft-tissue contrast of 4D-T2w MRI motivates its use for delineation in radiotherapy treatment planning. We address current limitations of slice-selective implementations, including thick slices and artefacts originating from data incompleteness and variable breathing. Materials and methodsA method was developed to calculate midposition and 4D-T2w images of the whole thorax from continuously acquired axial and sagittal 2D-T2w MRI (1.5 × 1.5 × 5.0 mm3). The method employed image-derived respiratory surrogates, deformable image registration and super-resolution reconstruction. Volunteer imaging and a respiratory motion phantom were used for validation. The minimum number of dynamic acquisitions needed to calculate a representative midposition image was investigated by retrospectively subsampling the data (10–30 dynamic acquisitions). ResultsSuper-resolution 4D-T2w MRI (1.0 × 1.0 × 1.0 mm3, 8 respiratory phases) did not suffer from data incompleteness and exhibited reduced stitching artefacts compared to sorted multi-slice MRI. Experiments using a respiratory motion phantom and colour-intensity projection images demonstrated a minor underestimation of the motion range. Midposition diaphragm differences in retrospectively subsampled acquisitions were <1.1 mm compared to the full dataset. 10 dynamic acquisitions were found sufficient to generate midposition MRI. ConclusionsA motion-modelling and super-resolution method was developed to calculate high quality 4D/midposition T2w MRI from orthogonal 2D-T2w MRI.
Highlights
Background and purposeThe superior soft-tissue contrast of 4D-T2w MRI motivates its use for delineation in radiotherapy treatment planning
Calculated colour-intensity projection images (CIPs) are independent of the binning and motion-modelling workflow and enable a comparison of the motion information exhibited by low-resolution 4D-T2w MRI and the unprocessed ground-truth phantom data
Low-resolution 4D-T2w MRI was reconstructed in 3.2 min for each orientation and total reconstruction time for super-resolution 4D/MidP-T2w was less than 23 min
Summary
Background and purposeThe superior soft-tissue contrast of 4D-T2w MRI motivates its use for delineation in radiotherapy treatment planning. Results: Super-resolution 4D-T2w MRI (1.0 Â 1.0 Â 1.0 mm3, 8 respiratory phases) did not suffer from data incompleteness and exhibited reduced stitching artefacts compared to sorted multi-slice MRI. An automated binning and super-resolution reconstruction method is introduced to calculate high-resolution distortion corrected MidP/4D-T2w MRI, without missing-data artefacts, from dynamically acquired axial and sagittal 2D-T2w MRI.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have