TY - JOUR
T1 - Inter-Observer Variability in MR-Based Target Volume Delineation of Uveal Melanoma
AU - Jaarsma-Coes, Myriam G.
AU - Klaassen, Lisa
AU - Verbist, Berit M.
AU - Vu, T. H. Khanh
AU - Klaver, Yvonne L. B.
AU - Rodrigues, Myra F.
AU - Nabarro, Claire
AU - Luyten, Gregorius P. M.
AU - Rasch, Coen R. N.
AU - van Herk, Marcel
AU - Beenakker, Jan-Willem M.
N1 - Funding Information: Sources of support: This work was supported by the Netherlands Organization for Scientific Research (NWO) [protons4vision 14654]. Publisher Copyright: © 2022 The Authors
PY - 2023/5/1
Y1 - 2023/5/1
N2 - Purpose: Several efforts are being undertaken toward MRI-based treatment planning for ocular proton therapy for uveal melanoma (UM). The interobserver variability of the gross target volume (GTV) on magnetic resonance imaging (MRI) is one of the important parameters to design safety margins for a reliable treatment. Therefore, this study assessed the interobserver variation in GTV delineation of UM on MRI. Methods and Materials: Six observers delineated the GTV in 10 different patients using the Big Brother contouring software. Patients were scanned at 3T MRI with a surface coil, and tumors were delineated separately on contrast enhanced 3DT1 (T1gd) and 3DT2-weighted scans with an isotropic acquisition resolution of 0.8 mm. Volume difference and overall local variation (median standard deviation of the distance between the delineated contours and the median contour) were analyzed for each GTV. Additionally, the local variation was analyzed for 4 interfaces: sclera, vitreous, retinal detachment, and tumor-choroid interface. Results: The average GTV was significantly larger on T1gd (0.57cm3) compared with T2 (0.51cm3, P = .01). A not significant higher interobserver variation was found on T1gd (0.41 mm) compared with T2 (0.35 mm). The largest variations were found at the tumor-choroid interface due to peritumoral enhancement (T1gd, 0.62 mm; T2, 0.52 mm). As a result, a larger part of this tumor-choroid interface appeared to be included on T1gd-based GTVs compared with T2, explaining the smaller volumes on T2. Conclusions: The interobserver variation of 0.4 mm on MRI are low with respect to the voxel size of 0.8 mm, enabling small treatment margins. We recommend delineation based on the T1gd-weighted scans, as choroidal tumor extensions might be missed.
AB - Purpose: Several efforts are being undertaken toward MRI-based treatment planning for ocular proton therapy for uveal melanoma (UM). The interobserver variability of the gross target volume (GTV) on magnetic resonance imaging (MRI) is one of the important parameters to design safety margins for a reliable treatment. Therefore, this study assessed the interobserver variation in GTV delineation of UM on MRI. Methods and Materials: Six observers delineated the GTV in 10 different patients using the Big Brother contouring software. Patients were scanned at 3T MRI with a surface coil, and tumors were delineated separately on contrast enhanced 3DT1 (T1gd) and 3DT2-weighted scans with an isotropic acquisition resolution of 0.8 mm. Volume difference and overall local variation (median standard deviation of the distance between the delineated contours and the median contour) were analyzed for each GTV. Additionally, the local variation was analyzed for 4 interfaces: sclera, vitreous, retinal detachment, and tumor-choroid interface. Results: The average GTV was significantly larger on T1gd (0.57cm3) compared with T2 (0.51cm3, P = .01). A not significant higher interobserver variation was found on T1gd (0.41 mm) compared with T2 (0.35 mm). The largest variations were found at the tumor-choroid interface due to peritumoral enhancement (T1gd, 0.62 mm; T2, 0.52 mm). As a result, a larger part of this tumor-choroid interface appeared to be included on T1gd-based GTVs compared with T2, explaining the smaller volumes on T2. Conclusions: The interobserver variation of 0.4 mm on MRI are low with respect to the voxel size of 0.8 mm, enabling small treatment margins. We recommend delineation based on the T1gd-weighted scans, as choroidal tumor extensions might be missed.
UR - http://www.scopus.com/inward/record.url?scp=85146064882&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.adro.2022.101149
DO - https://doi.org/10.1016/j.adro.2022.101149
M3 - Article
C2 - 36691449
SN - 2452-1094
VL - 8
JO - Advances in Radiation Oncology
JF - Advances in Radiation Oncology
IS - 3
M1 - 101149
ER -