title: Intra-rater variability in low-grade glioma segmentation.
abstract: Assessment of size and growth are key radiological factors in low-grade gliomas (LGGs), both for prognostication and treatment evaluation, but the reliability of LGG-segmentation is scarcely studied. With a diffuse and invasive growth pattern, usually without contrast enhancement, these tumors can be difficult to delineate. The aim of this study was to investigate the intra-observer variability in LGG-segmentation for a radiologist without prior segmentation experience. Pre-operative 3D FLAIR images of 23 LGGs were segmented three times in the software 3D Slicer. Tumor volumes were calculated, together with the absolute and relative difference between the segmentations. To quantify the intra-rater variability, we used the Jaccard coefficient comparing both two (J2) and three (J3) segmentations as well as the Hausdorff Distance (HD). The variability measured with J2 improved significantly between the two last segmentations compared to the two first, going from 0.87 to 0.90 (p = 0.04). Between the last two segmentations, larger tumors showed a tendency towards smaller relative volume difference (p = 0.07), while tumors with well-defined borders had significantly less variability measured with both J2 (p = 0.04) and HD (p < 0.01). We found no significant relationship between variability and histological sub-types or Apparent Diffusion Coefficients (ADC). We found that the intra-rater variability can be considerable in serial LGG-segmentation, but the variability seems to decrease with experience and higher grade of border conspicuity. Our findings highlight that some criteria defining tumor borders and progression in 3D volumetric segmentation is needed, if moving from 2D to 3D assessment of size and growth of LGGs.
authors.affiliation: Department of Radiology and Nuclear Medicine, St. Olavs University Hospital, P.O. Box 3250, Sluppen, 7006, Trondheim, Norway. hans.kr.b@gmail.com.|Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU, Norwegian University of Science and Technology, Trondheim, Norway. hans.kr.b@gmail.com.
authors.forename: Hans Kristian
authors.initials: HK
authors.lastname: Bø
authors.affiliation: Department of Neurosurgery, St. Olavs University Hospital, Trondheim, Norway.|Department of Neuroscience, Faculty of Medicine, NTNU, Norwegian University of Science and Technology, Trondheim, Norway.|National Competence Centre for Ultrasound and Image Guided Therapy, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: Ole
authors.initials: O
authors.lastname: Solheim
authors.affiliation: Department of Neurosurgery, St. Olavs University Hospital, Trondheim, Norway.|Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden.|Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden.
authors.forename: Asgeir Store
authors.initials: AS
authors.lastname: Jakola
authors.affiliation: Department of Radiology and Nuclear Medicine, St. Olavs University Hospital, P.O. Box 3250, Sluppen, 7006, Trondheim, Norway.
authors.forename: Kjell-Arne
authors.initials: KA
authors.lastname: Kvistad
authors.affiliation: National Competence Centre for Ultrasound and Image Guided Therapy, St. Olavs University Hospital, Trondheim, Norway.|SINTEF, Technology and Society, Department of Medical Technology, Trondheim, Norway.
authors.forename: Ingerid
authors.initials: I
authors.lastname: Reinertsen
authors.affiliation: Department of Radiology and Nuclear Medicine, St. Olavs University Hospital, P.O. Box 3250, Sluppen, 7006, Trondheim, Norway.|Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Erik Magnus
authors.initials: EM
authors.lastname: Berntsen
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D015588:Observer Variation; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Glioma; Intra-rater variability; Magnetic resonance imaging; Segmentation