Preliminary study of cine-MRI compression in MR-guided radiotherapy

Jiawen Shang; Peng Huang; Ke Zhang; Zhihui Hu; Hui Yan

doi:10.21037/qims-23-690

Preliminary study of cine-MRI compression in MR-guided radiotherapy

Quant Imaging Med Surg. 2023 Dec 1;13(12):8009-8019. doi: 10.21037/qims-23-690. Epub 2023 Sep 18.

Authors

Jiawen Shang^#¹, Peng Huang^#¹, Ke Zhang^#¹, Zhihui Hu¹, Hui Yan¹

Affiliation

¹ Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

^# Contributed equally.

Abstract

Background: Cine-magnetic resonance imaging (MRI) is currently used in real-time tumor tracking during magnetic resonance (MR)-guided radiotherapy. As a type of MRI specified for motion tracking, a few minutes' acquisition results in thousands of 2-dimensional (2D) images. For MR-guided radiotherapy consisting of multiple treatment fractions, the large number of cine-MRI images would be disproportionate to the tight clinical data storage available. To alleviate this issue, the feasibility of compression of cine-MRI via video encoders was investigated in this study.

Methods: The cine-MRI images were first sorted into 3 sequences according to their plane orientations. Then, each sequence was reordered according to their acquisition times [time-based (TB)] or content similarities [similarity-based (SB)]. As a result, 3 sequences were obtained for 3 plan orientations. Next, the obtained sequences were processed by a video encoder and the corresponding 3 video files were achieved. We employed 3 popular video encoders: Motion JPEG (M-JPEG), Advanced Video Coding (AVC), and High Efficiency Video Coding (HEVC). The performances of the sequence reordering methods and video encoders were evaluated based on a total of 150 image sets.

Results: The mean correlation quantities for SB sequences were higher than those for TB sequences by 3% (sagittal), 2% (coronal), and 1% (transverse), respectively. The average compression ratio (CR) yielded by the SB sequences was higher than that achieved by the TB sequences. Comparing with M-JPEG, the CRs obtained by AVC and HEVC were increased by 58% and 62% (sagittal), 16% and 23% (coronal), and 48% and 56% (transverse), respectively. Among the 3 video encoders, the highest CRs and restoration accuracy were achieved by HEVC.

Conclusions: HEVC with inter-frame coding is more effective in reducing the redundant information in consecutive images. It is feasible to implement the video encoder for high-performance cine-MRI compression.

Keywords: Cine-magnetic resonance imaging (cine-MRI); compression; data storage; magnetic resonance-guided radiotherapy (MR-guided radiotherapy); video encoder.