TY - JOUR
T1 - Real-time non-rigid 3D respiratory motion estimation for MR-guided radiotherapy using MR-MOTUS
AU - Huttinga, Niek R F
AU - Bruijnen, Tom
AU - Van den Berg, Cornelis A T
AU - Sbrizzi, Alessandro
N1 - Funding Information:
Manuscript received July 20, 2021; revised August 25, 2021; accepted September 6, 2021. Date of publication September 14, 2021; date of current version February 2, 2022. This work was supported in part by the Dutch Research Council (NWO) under Grant 15115. (Corresponding author: Niek R. F. Huttinga.) This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by the Institutional Review Board of the UMC Utrecht, and performed in line with the relevant guidelines and regulations.
Publisher Copyright:
© 2021 IEEE.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - The MR-Linac is a combination of an MR-scanner and radiotherapy linear accelerator (Linac) which holds the promise to increase the precision of radiotherapy treatments with MR-guided radiotherapy by monitoring motion during radiotherapy with MRI, and adjusting the radiotherapy plan accordingly. Optimal MR-guidance for respiratory motion during radiotherapy requires MR-based 3D motion estimation with a latency of 200-500 ms. Currently this is still challenging since typical methods rely on MR-images, and are therefore limited by the 3D MR-imaging latency. In this work, we present a method to perform non-rigid 3D respiratory motion estimation with 170 ms latency, including both acquisition and reconstruction. The proposed method called real-time low-rank MR-MOTUS reconstructs motion-fields directly from {k} -space data, and leverages an explicit low-rank decomposition of motion-fields to split the large scale 3D+t motion-field reconstruction problem posed in our previous work into two parts: (I) a medium-scale offline preparation phase and (II) a small-scale online inference phase which exploits the results of the offline phase for real-time computations. The method was validated on free-breathing data of five volunteers, acquired with a 1.5T Elekta Unity MR-Linac. Results show that the reconstructed 3D motion-field are anatomically plausible, highly correlated with a self-navigation motion surrogate ( R=0.975 pm 0.0110), and can be reconstructed with a total latency of 170 ms that is sufficient for real-time MR-guided abdominal radiotherapy.
AB - The MR-Linac is a combination of an MR-scanner and radiotherapy linear accelerator (Linac) which holds the promise to increase the precision of radiotherapy treatments with MR-guided radiotherapy by monitoring motion during radiotherapy with MRI, and adjusting the radiotherapy plan accordingly. Optimal MR-guidance for respiratory motion during radiotherapy requires MR-based 3D motion estimation with a latency of 200-500 ms. Currently this is still challenging since typical methods rely on MR-images, and are therefore limited by the 3D MR-imaging latency. In this work, we present a method to perform non-rigid 3D respiratory motion estimation with 170 ms latency, including both acquisition and reconstruction. The proposed method called real-time low-rank MR-MOTUS reconstructs motion-fields directly from {k} -space data, and leverages an explicit low-rank decomposition of motion-fields to split the large scale 3D+t motion-field reconstruction problem posed in our previous work into two parts: (I) a medium-scale offline preparation phase and (II) a small-scale online inference phase which exploits the results of the offline phase for real-time computations. The method was validated on free-breathing data of five volunteers, acquired with a 1.5T Elekta Unity MR-Linac. Results show that the reconstructed 3D motion-field are anatomically plausible, highly correlated with a self-navigation motion surrogate ( R=0.975 pm 0.0110), and can be reconstructed with a total latency of 170 ms that is sufficient for real-time MR-guided abdominal radiotherapy.
KW - Iterative reconstruction
KW - Magnetic Resonance Imaging
KW - Motion estimation
KW - MR-guided radiotherapy
KW - Real-time reconstruction
KW - Magnetic resonance imaging
UR - http://www.scopus.com/inward/record.url?scp=85115140768&partnerID=8YFLogxK
U2 - 10.1109/TMI.2021.3112818
DO - 10.1109/TMI.2021.3112818
M3 - Article
C2 - 34520351
SN - 0278-0062
VL - 41
SP - 332
EP - 346
JO - IEEE transactions on medical imaging
JF - IEEE transactions on medical imaging
IS - 2
ER -