Investigation of the clinical inter-observer bias in prostate fiducial marker image registration between CT and MR images

Emilia Persson; Sevgi Emin; Jonas Scherman; Christian Jamtheim Gustafsson; Patrik Brynolfsson; Sofie Ceberg; Adalsteinn Gunnlaugsson; Lars E. Olsson

doi:10.1186/s13014-021-01865-8

Investigation of the clinical inter-observer bias in prostate fiducial marker image registration between CT and MR images

Emilia Persson, Sevgi Emin, Jonas Scherman, Christian Jamtheim Gustafsson, Patrik Brynolfsson, Sofie Ceberg, Adalsteinn Gunnlaugsson, Lars E. Olsson

Skåne University Hospital

Research output: Contribution to journal › Article › peer-review

Abstract

Background and purpose: Inter-modality image registration between computed tomography (CT) and magnetic resonance (MR) images is associated with systematic uncertainties and the magnitude of these uncertainties is not well documented. The purpose of this study was to investigate the potential uncertainty of gold fiducial marker (GFM) registration for localized prostate cancer and to estimate the inter-observer bias in a clinical setting. Methods: Four experienced observers registered CT and MR images for 42 prostate cancer patients. Manual GFM identification was followed by a landmark-based registration. The absolute difference between observers in GFM identification and the displacement of the clinical target volume (CTV) was investigated. The CTV center of mass (CoM) vector displacements, DICE-index and Hausdorff distances for the observer registrations were compared against a clinical baseline registration. The time allocated for the manual registrations was compared. Results: Absolute difference in GFM identification between observers ranged from 0.0 to 3.0 mm. The maximum CTV CoM displacement from the clinical baseline was 3.1 mm. Displacements larger than or equal to 1 mm, 2 mm and 3 mm were 46%, 18% and 4%, respectively. No statistically significant difference was detected between observers in terms of CTV displacement. Median DICE-index and Hausdorff distance for the CTV, with their respective ranges were 0.94 [0.70–1.00] and 2.5 mm [0.7–8.7]. Conclusions: Registration of CT and MR images using GFMs for localized prostate cancer patients was subject to inter-observer bias on an individual patient level. A CTV displacement as large as 3 mm occurred for individual patients. These results show that GFM registration in a clinical setting is associated with uncertainties, which motivates the removal of inter-modality registrations in the radiotherapy workflow and a transition to an MRI-only workflow for localized prostate cancer.

Original language	English
Article number	150
Journal	Radiation Oncology
Volume	16
Issue number	1
DOIs	https://doi.org/10.1186/s13014-021-01865-8
Publication status	Published - 2021 Dec

Bibliographical note

Funding Information:
Open access funding provided by Lund University. This work was supported by Gentle Radiotherapy and The Swedish Agency for Innovation systems (VINNOVA) under Grant 2016-03847 and 2016-02529, “Allmänna sjukhusets I Malmö Stiftelse för bekämpande av cancer”; Fru Berta Kamprads stiftelse för utforskning och bekämpning av cancersjukdomar, Lund, SUS foundations, Region Skåne and by “Onkologiska klinikens stiftelse för bekämpande av cancer”.

Publisher Copyright:
© 2021, The Author(s).

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Subject classification (UKÄ)

Other Physics Topics
Radiology, Nuclear Medicine and Medical Imaging

Keywords

Computed tomography
Fiducial marker
Image registration
Inter-observer
Magnetic resonance imaging
Prostate cancer
Registration uncertainty

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10.1186/s13014-021-01865-8Licence: CC BY

Cite this

@article{156ed886b4ae4cb38b6716fb42bc5271,

title = "Investigation of the clinical inter-observer bias in prostate fiducial marker image registration between CT and MR images",

abstract = "Background and purpose: Inter-modality image registration between computed tomography (CT) and magnetic resonance (MR) images is associated with systematic uncertainties and the magnitude of these uncertainties is not well documented. The purpose of this study was to investigate the potential uncertainty of gold fiducial marker (GFM) registration for localized prostate cancer and to estimate the inter-observer bias in a clinical setting. Methods: Four experienced observers registered CT and MR images for 42 prostate cancer patients. Manual GFM identification was followed by a landmark-based registration. The absolute difference between observers in GFM identification and the displacement of the clinical target volume (CTV) was investigated. The CTV center of mass (CoM) vector displacements, DICE-index and Hausdorff distances for the observer registrations were compared against a clinical baseline registration. The time allocated for the manual registrations was compared. Results: Absolute difference in GFM identification between observers ranged from 0.0 to 3.0 mm. The maximum CTV CoM displacement from the clinical baseline was 3.1 mm. Displacements larger than or equal to 1 mm, 2 mm and 3 mm were 46%, 18% and 4%, respectively. No statistically significant difference was detected between observers in terms of CTV displacement. Median DICE-index and Hausdorff distance for the CTV, with their respective ranges were 0.94 [0.70–1.00] and 2.5 mm [0.7–8.7]. Conclusions: Registration of CT and MR images using GFMs for localized prostate cancer patients was subject to inter-observer bias on an individual patient level. A CTV displacement as large as 3 mm occurred for individual patients. These results show that GFM registration in a clinical setting is associated with uncertainties, which motivates the removal of inter-modality registrations in the radiotherapy workflow and a transition to an MRI-only workflow for localized prostate cancer.",

keywords = "Computed tomography, Fiducial marker, Image registration, Inter-observer, Magnetic resonance imaging, Prostate cancer, Registration uncertainty",

author = "Emilia Persson and Sevgi Emin and Jonas Scherman and {Jamtheim Gustafsson}, Christian and Patrik Brynolfsson and Sofie Ceberg and Adalsteinn Gunnlaugsson and Olsson, {Lars E.}",

note = "Funding Information: Open access funding provided by Lund University. This work was supported by Gentle Radiotherapy and The Swedish Agency for Innovation systems (VINNOVA) under Grant 2016-03847 and 2016-02529, “Allm{\"a}nna sjukhusets I Malm{\"o} Stiftelse f{\"o}r bek{\"a}mpande av cancer”; Fru Berta Kamprads stiftelse f{\"o}r utforskning och bek{\"a}mpning av cancersjukdomar, Lund, SUS foundations, Region Sk{\aa}ne and by “Onkologiska klinikens stiftelse f{\"o}r bek{\"a}mpande av cancer”. Publisher Copyright: {\textcopyright} 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.",

year = "2021",

month = dec,

doi = "10.1186/s13014-021-01865-8",

language = "English",

volume = "16",

journal = "Radiation Oncology",

issn = "1748-717X",

publisher = "BioMed Central (BMC)",

number = "1",

}

TY - JOUR

T1 - Investigation of the clinical inter-observer bias in prostate fiducial marker image registration between CT and MR images

AU - Persson, Emilia

AU - Emin, Sevgi

AU - Scherman, Jonas

AU - Jamtheim Gustafsson, Christian

AU - Brynolfsson, Patrik

AU - Ceberg, Sofie

AU - Gunnlaugsson, Adalsteinn

AU - Olsson, Lars E.

N1 - Funding Information: Open access funding provided by Lund University. This work was supported by Gentle Radiotherapy and The Swedish Agency for Innovation systems (VINNOVA) under Grant 2016-03847 and 2016-02529, “Allmänna sjukhusets I Malmö Stiftelse för bekämpande av cancer”; Fru Berta Kamprads stiftelse för utforskning och bekämpning av cancersjukdomar, Lund, SUS foundations, Region Skåne and by “Onkologiska klinikens stiftelse för bekämpande av cancer”. Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/12

Y1 - 2021/12

N2 - Background and purpose: Inter-modality image registration between computed tomography (CT) and magnetic resonance (MR) images is associated with systematic uncertainties and the magnitude of these uncertainties is not well documented. The purpose of this study was to investigate the potential uncertainty of gold fiducial marker (GFM) registration for localized prostate cancer and to estimate the inter-observer bias in a clinical setting. Methods: Four experienced observers registered CT and MR images for 42 prostate cancer patients. Manual GFM identification was followed by a landmark-based registration. The absolute difference between observers in GFM identification and the displacement of the clinical target volume (CTV) was investigated. The CTV center of mass (CoM) vector displacements, DICE-index and Hausdorff distances for the observer registrations were compared against a clinical baseline registration. The time allocated for the manual registrations was compared. Results: Absolute difference in GFM identification between observers ranged from 0.0 to 3.0 mm. The maximum CTV CoM displacement from the clinical baseline was 3.1 mm. Displacements larger than or equal to 1 mm, 2 mm and 3 mm were 46%, 18% and 4%, respectively. No statistically significant difference was detected between observers in terms of CTV displacement. Median DICE-index and Hausdorff distance for the CTV, with their respective ranges were 0.94 [0.70–1.00] and 2.5 mm [0.7–8.7]. Conclusions: Registration of CT and MR images using GFMs for localized prostate cancer patients was subject to inter-observer bias on an individual patient level. A CTV displacement as large as 3 mm occurred for individual patients. These results show that GFM registration in a clinical setting is associated with uncertainties, which motivates the removal of inter-modality registrations in the radiotherapy workflow and a transition to an MRI-only workflow for localized prostate cancer.

AB - Background and purpose: Inter-modality image registration between computed tomography (CT) and magnetic resonance (MR) images is associated with systematic uncertainties and the magnitude of these uncertainties is not well documented. The purpose of this study was to investigate the potential uncertainty of gold fiducial marker (GFM) registration for localized prostate cancer and to estimate the inter-observer bias in a clinical setting. Methods: Four experienced observers registered CT and MR images for 42 prostate cancer patients. Manual GFM identification was followed by a landmark-based registration. The absolute difference between observers in GFM identification and the displacement of the clinical target volume (CTV) was investigated. The CTV center of mass (CoM) vector displacements, DICE-index and Hausdorff distances for the observer registrations were compared against a clinical baseline registration. The time allocated for the manual registrations was compared. Results: Absolute difference in GFM identification between observers ranged from 0.0 to 3.0 mm. The maximum CTV CoM displacement from the clinical baseline was 3.1 mm. Displacements larger than or equal to 1 mm, 2 mm and 3 mm were 46%, 18% and 4%, respectively. No statistically significant difference was detected between observers in terms of CTV displacement. Median DICE-index and Hausdorff distance for the CTV, with their respective ranges were 0.94 [0.70–1.00] and 2.5 mm [0.7–8.7]. Conclusions: Registration of CT and MR images using GFMs for localized prostate cancer patients was subject to inter-observer bias on an individual patient level. A CTV displacement as large as 3 mm occurred for individual patients. These results show that GFM registration in a clinical setting is associated with uncertainties, which motivates the removal of inter-modality registrations in the radiotherapy workflow and a transition to an MRI-only workflow for localized prostate cancer.

KW - Computed tomography

KW - Fiducial marker

KW - Image registration

KW - Inter-observer

KW - Magnetic resonance imaging

KW - Prostate cancer

KW - Registration uncertainty

U2 - 10.1186/s13014-021-01865-8

DO - 10.1186/s13014-021-01865-8

M3 - Article

C2 - 34399806

AN - SCOPUS:85112691094

SN - 1748-717X

VL - 16

JO - Radiation Oncology

JF - Radiation Oncology

IS - 1

M1 - 150

ER -

Investigation of the clinical inter-observer bias in prostate fiducial marker image registration between CT and MR images

Abstract

Bibliographical note

Subject classification (UKÄ)

Keywords

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