Comparison of Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) for breast target volume delineation in prone and supine positions

Elise M. Pogson, Geoff P. Delaney, Verity Ahern, Miriam Boxer, Christine Chan, Steven David, Marion Dimigen, Jennifer A. Harvey, Mei L. Yap, [and eleven others]

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Purpose/Objective(s): MRI provides no ionizing radiation dose (allowing inter and intra fraction imaging), improved soft tissue contrast and potentially improved conformity in delineation than CT. This study aimed to determine if T2 weighted magnetic resonance imaging improves seroma cavity (SC) and Whole Breast (WB) inter-observer conformity for radiotherapy purposes compared with the gold standard of CT, both in the prone and supine positions. Methods and Materials: Eleven observers (two Radiologists and nine Radiation Oncologists) delineated SC and WB Clinical Target Volumes (CTVs) on T2-weighted MRI and CT supine and prone scans (4 scans per patient) for 33 patient datasets. Individual observer’s volumes were compared using the Dice Similarity Coefficient (DSC), Volume overlap Index (VOI), Centre of Mass (COM) shift and Hausdorff Distances (HD). An average Cavity Visualization Score (CVS) was also determined. Results: Imaging modality did not affect inter-observer variation for WB CTVs. Prone WB CTVs were larger in volume and more conformal than Supine CTVs (on both MRI and CT). SC volumes were larger on CT than MRI. SC volumes proved to be comparable in inter-observer conformity in both modalities (VOI of 0.57±0.03 for CT supine, 0.52±0.04 for MR supine, 0.56±0.03 for CT prone and 0.55±0.04 for MR prone) however after registering modalities together the inter-modality variation (DSC of 0.41±0.05 for supine and 0.38±0.04 for prone) was larger than the inter-observer variability for SC despite the location typically remaining constant. Conclusions: MRI inter-observer variation was comparable to CT for the WB CTV and SC delineation, in both prone and supine positions. Whilst the CVS and inter-observer concordance was not significantly higher for MRI than CT, the SCs were smaller on MRI, potentially due to clearer SC definition, especially on T2-weighted MR images.
Original languageEnglish
Pages (from-to)905-912
Number of pages8
JournalInternational Journal of Radiation Oncology, Biology, Physics
Volume96
Issue number4
DOIs
Publication statusPublished - 2016

Open Access - Access Right Statement

© 2016. Elsevier Inc. All rights reserved. This paper is made available in Western Sydney University ResearchDirect in accordance with publisher policies.

Keywords

  • magnetic resonance imaging
  • oncology
  • radiotherapy

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