Multi-observer contouring of male pelvic anatomy: Highly variable agreement across conventional and emerging structures of interest

Authors

Dale Roach, University of New South Wales, Ingham Institute for Applied Medical Research
Lois C. Holloway, University of New South Wales, Ingham Institute for Applied Medical Research, University of Wollongong, Liverpool and Macarthur Cancer Therapy CentresFollow
Michael G. Jameson, University of New South Wales, Ingham Institute for Applied Medical Research, University of Wollongong, Liverpool and Macarthur Cancer Therapy Centres
Jason A. Dowling, University of New South Wales, University of Wollongong, Royal Brisbane Hospital, University of NewcastleFollow
Angel Kennedy, Sir Charles Gairdner Hospital, Perth
Peter B. Greer, University of Newcastle, Calvary Mater Newcastle Hospital
Michele Krawiec, Sir Charles Gairdner Hospital, Perth
Robba Rai, University of New South Wales, Ingham Institute for Applied Medical Research, Liverpool and Macarthur Cancer Therapy Centres
James W. Denham, University of Newcastle
Jeremiah F. De Leon, Illawarra Cancer Care Centre
Karen Lim, Liverpool and Macarthur Cancer Therapy Centres, University of New South Wales
Megan Berry, Liverpool and Macarthur Cancer Therapy Centres, University of New South Wales
Rohen White, Sir Charles Gairdner Hospital, Perth
Sean Bydder, Sir Charles Gairdner Hospital, Perth
Hendrick Tan, Sir Charles Gairdner Hospital, Perth
Jeremy Croker, Fiona Stanley Hospital
Alycea McGrath, Sir Charles Gairdner Hospital, Perth
John Matthews, Auckland City HospitalFollow
Robert Smeenk, Radboud University Medical Center
Martin A. Ebert, University of Wollongong, Sir Charles Gairdner Hospital, Perth, University of Western Australia

RIS ID

132638

Publication Details

Roach, D., Holloway, L. C., Jameson, M. G., Dowling, J. A., Kennedy, A., Greer, P. B., Krawiec, M., Rai, R., Denham, J., De Leon, J., Lim, K., Berry, M. E., White, R. T., Bydder, S. A., Tan, H. T., Croker, J. D., McGrath, A., Matthews, J., Smeenk, R. J. & Ebert, M. A. (2019). Multi-observer contouring of male pelvic anatomy: Highly variable agreement across conventional and emerging structures of interest. Journal of Medical Imaging and Radiation Oncology, 63 (2), 264-271.

Abstract

Introduction: This study quantified inter‐observer contouring variations for multiple male pelvic structures, many of which are of emerging relevance for prostate cancer radiotherapy progression and toxicity response studies.

Methods: Five prostate cancer patient datasets (CT and T2‐weighted MR) were distributed to 13 observers for contouring. CT structures contoured included the clinical target volume (CTV), seminal vesicles, rectum, colon, bowel bag, bladder and peri‐rectal space (PRS). MR contours included CTV, trigone, membranous urethra, penile bulb, neurovascular bundle and multiple pelvic floor muscles. Contouring variations were assessed using the intraclass correlation coefficient (ICC), Dice similarity coefficient (DSC), and multiple additional metrics.

Results: Clinical target volume (CT and MR), bladder, rectum and PRS contours showed excellent inter‐observer agreement (median ICC = 0.97; 0.99; 1.00; 0.95; 0.90, DSC = 0.83 ± 0.05; 0.88 ± 0.05; 0.93 ± 0.03; 0.81 ± 0.07; 0.80 ± 0.06, respectively). Seminal vesicle contours were more variable (ICC = 0.75, DSC = 0.73 ± 0.14), while colon and bowel bag contoured volumes were consistent (ICC = 0.97; 0.97), but displayed poor overlap (DSC = 0.58 ± 0.22; 0.67 ± 0.21). Smaller MR structures showed significant inter‐observer variations, with poor overlap for trigone, membranous urethra, penile bulb, and left and right neurovascular bundles (DSC = 0.44 ± 0.22; 0.41 ± 0.21; 0.66 ± 0.21; 0.16 ± 0.17; 0.15 ± 0.15). Pelvic floor muscles recorded moderate to strong inter‐observer agreement (ICC = 0.50–0.97), although large outlier variations were observed.

Conclusions: Inter‐observer contouring variation was significant for multiple pelvic structures contoured on MR.