Inter-observer variation in gross tumour volume delineation of oesophageal cancer on MR, CT and PET/CT
Abstract
Background. The aim of our study was to assess the inter-observer variability in delineation of the gross tumour volume (GTV) of oesophageal cancer on magnetic resonance (MR) in comparison to computed tomography (CT) and positron emission tomography and CT (PET/CT).
Patients and methods. Twenty-three consecutive patients with oesophageal cancer treated with chemo-radiotherapy were enrolled. All patients had PET/CT and MR imaging in treatment position. Five observers independently delineated the GTV on CT alone, MR alone, CT with co-registered MR, PET/CT and MR with co-registered PET/CT. Volumes of GTV were measured per patient and imaging modality. Inter-observer agreement, expressed in generalized conformity index (CIgen), volumetric conformity index (VCI), planar conformity index (PCI) and inter-delineation distance (IDD) were calculated per patient and imaging modality.
Results. GTV volume was significantly lower on MR (33.03 cm3) compared to CT (37.1 cm3; p=0.002) and on PET/CT MR (35.2 cm3; p=0.018) compared to PET/CT (39.1 cm3). The CIgen was lowest on CT (0.56) and highest on PET/CT MR (0.67). The difference in CIgen between MR (0.61) and CT was borderline significant (p=0.048). The VCI was significantly higher on MR (0.71; p=0.007) and on CT MR (0.71; p=0.004) compared to CT (0.67). The PCI was significantly higher on CT MR (0.67; p=0.031) compared to CT (0.64). The largest differences were observed in the cranio-caudal direction.
Conclusions.The highest inter-observer agreement was found for PET/CT MR and the lowest for CT. MR could provide additional information about the specifics of the tumour.
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Copyright (c) 2024 Ajra Šečerov Ermenc, Primoz Peterlin, Franc Anderluh, Jasna But-Hadzic, Ana Jeromen-Peressutti, Vaneja Velenik, Barbara Segedin

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