Addition of MRI for CT-based pancreatic tumor delineation: a feasibility study

作者：Gurney Champion Oliver J^*; Versteijne Eva; van der Horst Astrid; Lens Eelco; Ruetten Heidi; Heerkens Hanne D; Paardekooper Gabriel M R M; Berbee Maaike; Rasch Coen R N; Stoker Jaap; Engelbrecht Marc R W; van Herk Marcel; Nederveen Aart J; Klaassen Remy; van Laarhoven Hanneke W M; van Tienhoven Geertjan; Bel Arjan

来源：Acta Oncologica, 2017, 56(7): 923-930.

DOI：10.1080/0284186X.2017.1304654

Purpose: To assess the effect of additional magnetic resonance imaging (MRI) alongside the planning computed tomography (CT) scan on target volume delineation in pancreatic cancer patients.Material and methods: Eight observers (radiation oncologists) from six institutions delineated the gross tumor volume (GTV) on 3DCT, and internal GTV (iGTV) on 4DCT of four pancreatic cancer patients, while MRI was available in a second window (CT+MRI). Variations in volume, generalized conformity index (CIgen), and overall observer variation, expressed as standard deviation (SD) of the distances between delineated surfaces, were analyzed. CIgen is a measure of overlap of the delineated iGTVs (1=full overlap, 0=no overlap). Results were compared with those from an earlier study that assessed the interobserver variation by the same observers on the same patients on CT without MRI (CT-only).Results: The maximum ratios between delineated volumes within a patient were 6.1 and 22.4 for the GTV (3DCT) and iGTV (4DCT), respectively. The average (root-mean-square) overall observer variations were SD=0.41cm (GTV) and SD=0.73cm (iGTV). The mean CIgen was 0.36 for GTV and 0.37 for iGTV. When compared to the iGTV delineated on CT-only, the mean volumes of the iGTV on CT+MRI were significantly smaller (32%, Wilcoxon signed-rank, p<.0005). The median volumes of the iGTV on CT+MRI were included for 97% and 92% in the median volumes of the iGTV on CT. Furthermore, CT+MRI showed smaller overall observer variations (root-mean-square SD=0.59cm) in six out of eight delineated structures compared to CT-only (root-mean-square SD=0.72cm). However, large local observer variations remained close to biliary stents and pathological lymph nodes, indicating issues with instructions and instruction compliance.Conclusions: The availability of MRI images during target delineation of pancreatic cancer on 3DCT and 4DCT resulted in smaller target volumes and reduced the interobserver variation in six out of eight delineated structures.

• 出版日期2017