PMID- 35605005
OWN - NLM
STAT- MEDLINE
DCOM- 20220525
LR  - 20220716
IS  - 1932-6203 (Electronic)
IS  - 1932-6203 (Linking)
VI  - 17
IP  - 5
DP  - 2022
TI  - Geometric distortion assessment in 3T MR images used for treatment planning in 
      cranial Stereotactic Radiosurgery and Radiotherapy.
PG  - e0268925
LID - 10.1371/journal.pone.0268925 [doi]
LID - e0268925
AB  - Magnetic Resonance images (MRIs) are employed in brain Stereotactic Radiosurgery 
      and Radiotherapy (SRS/SRT) for target and/or critical organ localization and 
      delineation. However, MRIs are inherently distorted, which also impacts the 
      accuracy of the Magnetic Resonance Imaging/Computed Tomography (MRI/CT) 
      co-registration process. In this phantom-based study, geometric distortion is 
      assessed in 3T T2-weighted images (T2WIs), while the efficacy of an MRI 
      distortion correction technique is also evaluated. A homogeneous polymer 
      gel-filled phantom was CT-imaged before being irradiated with 26 4-mm Gamma Knife 
      shots at predefined locations (reference control points). The irradiated phantom 
      was MRI-scanned at 3T, implementing a T2-weighted protocol suitable for SRS/SRT 
      treatment planning. The centers of mass of all shots were identified in the 3D 
      image space by implementing an iterative localization algorithm and served as the 
      evaluated control points for MRI distortion detection. MRIs and CT images were 
      spatially co-registered using a mutual information algorithm. The inverse 
      transformation matrix was applied to the reference control points and compared 
      with the corresponding MRI-identified ones to evaluate the overall spatial 
      accuracy of the MRI/CT dataset. The mean image distortion correction technique 
      was implemented, and resulting MRI-corrected control points were compared against 
      the corresponding reference ones. For the scanning parameters used, increased MRI 
      distortion (>1mm) was detected at areas distant from the MRI isocenter (>5cm), 
      while median radial distortion was 0.76mm. Detected offsets were slightly higher 
      for the MRI/CT dataset (0.92mm median distortion). The mean image distortion 
      correction improves geometric accuracy, but residual distortion cannot be 
      considered negligible (0.51mm median distortion). For all three datasets studied, 
      a statistically significant positive correlation between detected spatial offsets 
      and their distance from the MRI isocenter was revealed. This work contributes 
      towards the wider adoption of 3T imaging in SRS/SRT treatment planning. The 
      presented methodology can be employed in commissioning and quality assurance 
      programmes of corresponding treatment workflows.
FAU - Theocharis, Stefanos
AU  - Theocharis S
AD  - Medical Physics Laboratory, Medical School, National and Kapodistrian University 
      of Athens, Athens, Greece.
FAU - Pappas, Eleftherios P
AU  - Pappas EP
AUID- ORCID: 0000-0003-4030-2241
AD  - Medical Physics Laboratory, Medical School, National and Kapodistrian University 
      of Athens, Athens, Greece.
FAU - Seimenis, Ioannis
AU  - Seimenis I
AD  - Medical Physics Laboratory, Medical School, National and Kapodistrian University 
      of Athens, Athens, Greece.
FAU - Kouris, Panagiotis
AU  - Kouris P
AD  - Medical Physics Laboratory, Medical School, National and Kapodistrian University 
      of Athens, Athens, Greece.
FAU - Dellios, Dimitrios
AU  - Dellios D
AUID- ORCID: 0000-0002-2576-6331
AD  - Medical Physics Laboratory, Medical School, National and Kapodistrian University 
      of Athens, Athens, Greece.
FAU - Kollias, Georgios
AU  - Kollias G
AD  - Medical Physics and Gamma Knife Department, Hygeia Hospital, Marousi, Greece.
FAU - Karaiskos, Pantelis
AU  - Karaiskos P
AUID- ORCID: 0000-0002-3665-2989
AD  - Medical Physics Laboratory, Medical School, National and Kapodistrian University 
      of Athens, Athens, Greece.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20220523
PL  - United States
TA  - PLoS One
JT  - PloS one
JID - 101285081
SB  - IM
MH  - Magnetic Resonance Imaging/methods
MH  - Phantoms, Imaging
MH  - *Radiosurgery/methods
MH  - Radiotherapy Planning, Computer-Assisted/methods
MH  - Tomography, X-Ray Computed
PMC - PMC9126373
COIS- The authors have declared that no competing interests exist.
EDAT- 2022/05/24 06:00
MHDA- 2022/05/26 06:00
PMCR- 2022/05/23
CRDT- 2022/05/23 13:54
PHST- 2022/01/26 00:00 [received]
PHST- 2022/05/10 00:00 [accepted]
PHST- 2022/05/23 13:54 [entrez]
PHST- 2022/05/24 06:00 [pubmed]
PHST- 2022/05/26 06:00 [medline]
PHST- 2022/05/23 00:00 [pmc-release]
AID - PONE-D-22-02573 [pii]
AID - 10.1371/journal.pone.0268925 [doi]
PST - epublish
SO  - PLoS One. 2022 May 23;17(5):e0268925. doi: 10.1371/journal.pone.0268925. 
      eCollection 2022.