Manual and semi-automated delineation of locally advanced rectal cancer subvolumes with diffusion-weighted MRI.

Autor: Hearn N; Department of Radiation Oncology, Sunshine Coast University Hospital, Birtinya, QLD, Australia.; ICON Cancer Centre, Maroochydore, QLD, Australia.; University of the Sunshine Coast, Sippy Downs, QLD, Australia., Bugg W; Department of Medical Imaging, Sunshine Coast University Hospital, Birtinya, QLD, Australia., Chan A; Department of Medical Imaging, Sunshine Coast University Hospital, Birtinya, QLD, Australia., Vignarajah D; Department of Radiation Oncology, Sunshine Coast University Hospital, Birtinya, QLD, Australia.; ICON Cancer Centre, Maroochydore, QLD, Australia., Cahill K; Department of Radiation Oncology, Sunshine Coast University Hospital, Birtinya, QLD, Australia., Atwell D; Department of Radiation Oncology, Sunshine Coast University Hospital, Birtinya, QLD, Australia.; ICON Cancer Centre, Maroochydore, QLD, Australia.; University of the Sunshine Coast, Sippy Downs, QLD, Australia., Lagopoulos J; University of the Sunshine Coast, Sippy Downs, QLD, Australia.; Sunshine Coast Mind and Neuroscience - Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia., Min M; Department of Radiation Oncology, Sunshine Coast University Hospital, Birtinya, QLD, Australia.; ICON Cancer Centre, Maroochydore, QLD, Australia.; University of the Sunshine Coast, Sippy Downs, QLD, Australia.
Jazyk: angličtina
Zdroj: The British journal of radiology [Br J Radiol] 2020 Oct 01; Vol. 93 (1114), pp. 20200543. Date of Electronic Publication: 2020 Sep 02.
DOI: 10.1259/bjr.20200543
Abstrakt: Objectives: To evaluate interobserver agreement for T 2 weighted ( T 2 W) and diffusion-weighted MRI (DW-MRI) contours of locally advanced rectal cancer (LARC); and to evaluate manual and semi-automated delineations of restricted diffusion tumour subvolumes.
Methods: 20 cases of LARC were reviewed by 2 radiation oncologists and 2 radiologists. Contours of gross tumour volume (GTV) on T 2 W, DW-MRI and co-registered T 2 W/DW-MRI were independently delineated and compared using Dice Similarity Coefficient (DSC), mean distance to agreement (MDA) and other metrics of interobserver agreement. Restricted diffusion subvolumes within GTVs were manually delineated and compared to semi-automatically generated contours corresponding to intratumoral apparent diffusion coefficient (ADC) centile values.
Results: Observers were able to delineate subvolumes of restricted diffusion with moderate agreement (DSC 0.666, MDA 1.92 mm). Semi-automated segmentation based on the 40th centile intratumoral ADC value demonstrated moderate average agreement with consensus delineations (DSC 0.581, MDA 2.44 mm), with errors noted in image registration and luminal variation between acquisitions. A small validation set of four cases with optimised planning MRI demonstrated improvement (DSC 0.669, MDA 1.91 mm).
Conclusion: Contours based on co-registered T 2 W and DW-MRI could be used for delineation of biologically relevant tumour subvolumes. Semi-automated delineation based on patient-specific intratumoral ADC thresholds may standardise subvolume delineation if registration between acquisitions is sufficiently accurate.
Advances in Knowledge: This is the first study to evaluate the feasibility of semi-automated diffusion-based subvolume delineation in LARC. This approach could be applied to dose escalation or 'dose painting' protocols to improve delineation reproducibility.
Databáze: MEDLINE
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