Open AccessMR SIGnature MAtching (MRSIGMA) with retrospective self-evaluation for real-time volumetric motion imaging
Author(s) -
Nathanael Kim,
Kathryn R. Tringale,
Christopher H. Crane,
Neetu Tyagi,
Ricardo Otazo
Publication year - 2021
Publication title -
physics in medicine and biology/physics in medicine and biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.312
H-Index - 191
eISSN - 1361-6560
pISSN - 0031-9155
DOI - 10.1088/1361-6560/ac2dd2
Subject(s) - computer science , sørensen–dice coefficient , computer vision , signature (topology) , artificial intelligence , real time mri , temporal resolution , image resolution , matching (statistics) , standard deviation , data acquisition , magnetic resonance imaging , mathematics , radiology , medicine , image (mathematics) , statistics , physics , image segmentation , geometry , quantum mechanics , operating system
Objective . MR SIGnature MAtching (MRSIGMA) is a real-time volumetric MRI technique to image tumor and organs at risk motion in real-time for radiotherapy applications, where a dictionary of high-resolution 3D motion states and associated motion signatures are computed first during offline training and real-time 3D imaging is performed afterwards using fast signature-only acquisition and signature matching. However, the lack of a reference image with similar spatial resolution and temporal resolution introduces significant challenges for in vivo validation. Approach . This work proposes a retrospective self-validation for MRSIGMA, where the same data used for real-time imaging are used to create a non-real-time reference for comparison. MRSIGMA with self-validation is tested in patients with liver tumors using quantitative metrics defined on the tumor and nearby organs-at-risk structures. The dice coefficient between contours defined on the real-time MRSIGMA and non-real-time reference was used to assess motion imaging performance. Main Results . Total latency (including signature acquisition and signature matching) was between 250 and 314 ms, which is sufficient for organs affected by respiratory motion. Mean ± standard deviation dice coefficient over time was 0.74 ± 0.03 for patients imaged without contrast agent and 0.87 ± 0.03 for patients imaged with contrast agent, which demonstrated high-performance real-time motion imaging. Signficance . MRSIGMA with self-evaluation provides a means to perform real-time volumetric MRI for organ motion tracking with quantitative performance measures.