Building MRI Videos for Planning Lung Cancer Radiotherapy
Posted: Wednesday, September 5, 2018
Although CT scans are normally used for planning radiotherapy treatment for lung cancer, MRI images may have better soft-tissue contrast. Thus, physicists at The Institute of Cancer Research and The Royal Marsden Hospital developed a new method using two-dimensional T2-weighted MRI images to build four-dimensional videos, which could be used for treatment planning. The study was published in Radiotherapy & Oncology by Andreas Wetscherek, PhD, of the Joint Department of Physics, and colleagues.
“Our study describes the development of a new technique for rebuilding static MRI images into moving videos, which could give MRI the edge over CT scans in the future planning of radiotherapy treatment,” Dr. Wetscherek revealed in a press release from The Institute of Cancer Research.
Videos made from combining MRI images have several limitations. Sometimes images of a particular slice are missed, the slices must be thick to provide the necessary field-of-view and signal-to-noise ratio, and variation in breathing can cause mistakes when images are stitched together.
The researchers took two-dimensional T2-weighted MRI images of the chest of eight healthy volunteers from multiple angles. Then they stitched them together into videos of the entire thorax using a technique called “super-resolution” reconstruction. This technique combines several low-resolution images from different angles into a final image with greater resolution. The videos they made had fewer stitching mistakes than previous methods of building videos from MRIs. The investigators subsampled their data after the fact to determine that 10 images in each orientation were enough to generate a representative midposition MRI.