The impact of 2D cine MR imaging parameters on automated tumor and organ localization for MR-guided real-time adaptive radiotherapy
Author(s)
Type
Journal Article
Abstract
2D cine MR imaging may be utilized to monitor rapidly moving tumors and organs-at-risk for
real-time adaptive radiotherapy. This study systematically investigates the impact of geometric
imaging parameters on the ability of 2D cine MR imaging to guide template-matching-driven
autocontouring of lung tumors and abdominal organs.
Abdominal 4D MR images were acquired of six healthy volunteers and thoracic 4D MR images
were obtained of eight lung cancer patients. At each breathing phase of the images, the left kidney
and gallbladder or lung tumor, respectively, were outlined as volumes of interest. These images
and contours were used to create artificial 2D cine MR images, while simultaneously serving as 3D
ground truth. We explored the impact of five different imaging parameters (pixel size, slice thickness,
imaging plane orientation, number and relative alignment of images as well as strategies to create
training images). For each possible combination of imaging parameters, we generated artificial 2D
cine MR images as training and test images. A template-matching algorithm used the training images
to determine the tumor or organ position in the test images. Subsequently, a 3D base contour was
shifted to the determined position and compared to the ground truth via centroid distance and Dice
similarity coefficient.
The median centroid distance between adapted and ground truth contours was 1.56mm for
the kidney, 3.81mm for the gallbladder and 1.03mm for the lung tumor (median Dice similarity
coefficient: 0.95, 0.72 and 0.93). We observed that a decrease in image resolution led to a modest
decrease in localization accuracy, especially for the small gallbladder. However, for all volumes of
interest localization accuracy varied substantially more between subjects than due to the different
imaging parameters.
Automated tumor and organ localization using 2D cine MR imaging and template-matchingbased autocontouring is robust against variation of geometric imaging parameters. Future work
and optimization efforts of 2D cine MR imaging for real-time adaptive radiotherapy is needed to
characterize the influence of sequence- and anatomical site-specific imaging contrast.
real-time adaptive radiotherapy. This study systematically investigates the impact of geometric
imaging parameters on the ability of 2D cine MR imaging to guide template-matching-driven
autocontouring of lung tumors and abdominal organs.
Abdominal 4D MR images were acquired of six healthy volunteers and thoracic 4D MR images
were obtained of eight lung cancer patients. At each breathing phase of the images, the left kidney
and gallbladder or lung tumor, respectively, were outlined as volumes of interest. These images
and contours were used to create artificial 2D cine MR images, while simultaneously serving as 3D
ground truth. We explored the impact of five different imaging parameters (pixel size, slice thickness,
imaging plane orientation, number and relative alignment of images as well as strategies to create
training images). For each possible combination of imaging parameters, we generated artificial 2D
cine MR images as training and test images. A template-matching algorithm used the training images
to determine the tumor or organ position in the test images. Subsequently, a 3D base contour was
shifted to the determined position and compared to the ground truth via centroid distance and Dice
similarity coefficient.
The median centroid distance between adapted and ground truth contours was 1.56mm for
the kidney, 3.81mm for the gallbladder and 1.03mm for the lung tumor (median Dice similarity
coefficient: 0.95, 0.72 and 0.93). We observed that a decrease in image resolution led to a modest
decrease in localization accuracy, especially for the small gallbladder. However, for all volumes of
interest localization accuracy varied substantially more between subjects than due to the different
imaging parameters.
Automated tumor and organ localization using 2D cine MR imaging and template-matchingbased autocontouring is robust against variation of geometric imaging parameters. Future work
and optimization efforts of 2D cine MR imaging for real-time adaptive radiotherapy is needed to
characterize the influence of sequence- and anatomical site-specific imaging contrast.
Date Issued
2018-11-22
Date Acceptance
2018-10-10
Citation
PHYSICS IN MEDICINE AND BIOLOGY, 2018, 63 (23), pp.1-16
ISSN
0031-9155
Publisher
IOP PUBLISHING LTD
Start Page
1
End Page
16
Journal / Book Title
PHYSICS IN MEDICINE AND BIOLOGY
Volume
63
Issue
23
Copyright Statement
© 2018 Institute of Physics and Engineering in Medicine. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence (http://creativecommons.org/licenses/by/3.0). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000451009100005&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Life Sciences & Biomedicine
Engineering, Biomedical
Radiology, Nuclear Medicine & Medical Imaging
Engineering
MR-linac
MR-guided radiotherapy
real-time adaptive radiotherapy
2D cine MR imaging
AUTOCONTOURING ALGORITHM
TRACKING RADIOTHERAPY
RESPIRATORY MOTION
RADIATION-THERAPY
TARGET TRACKING
XCAT PHANTOM
LUNG-CANCER
COMPENSATION
IRRADIATION
MOVEMENT
Publication Status
Published
Article Number
ARTN 235005
Date Publish Online
2018-11-22