Abstract
The aims of this study were to evaluate the intra- and interobserver reproducibility of manual segmentation of bone sarcomas in magnetic resonance imaging (MRI) studies and to compare manual and semiautomatic segmentation methods. This retrospective study included twelve osteosarcoma and eight Ewing sarcoma MRI studies performed prior to any therapeutic intervention. All cases were histopathologically confirmed. Three radiologists used 3D-Slicer software to perform manual segmentation of bone sarcomas in a blinded and independent manner. One radiologist segmented manually and also performed semiautomatic segmentation with the GrowCut tool. Segmentation exercises were timed for comparison. The dice similarity coefficient (DSC) and Hausdorff distance (HD) were used to evaluate similarity between the segmentation results and further statistical analyses were performed to compare DSC, HD, and volumetric results. Manual segmentation was reproducible with intraobserver DSC varying from 0.83 to 0.97 and HD from 3.37 to 28.73 mm. Interobserver DSC of manual segmentation showed variation from 0.73 to 0.97 and HD from 3.93 to 33.40 mm. Semiautomatic segmentation compared to manual segmentation resulted in DSCs of 0.71−0.96 and HDs of 5.38−31.54 mm. Semiautomatic segmentation required significantly less time compared to manual segmentation (P value ≤0.05). Among all situations compared, tumor volumetry did not show significant statistical differences (P value >0.05). We found excellent intra- and interobserver agreement for manual segmentation of osteosarcoma and Ewing sarcoma. There was high similarity between manual and semiautomatic segmentation, with a significant reduction of segmentation time using the semiautomatic method.
Highlights
Primary bone sarcomas are rare and represent about 0.2% of all malignant tumors in the general population [1], but about 5% of all primary malignant neoplasms in the pediatric population, with osteosarcoma and Ewing sarcoma being the most frequent in this group [2,3]
To the best of our knowledge, there are no studies published in the literature that have compared manual and semiautomatic segmentation of bone sarcomas in Magnetic resonance imaging (MRI) or validated semiautomatic segmentation of osteosarcoma and Ewing sarcoma
MRI is considered the method of choice for evaluating intra- and extra-osseous tumor extension in bone sarcomas, and for the assessment of infiltration of adjacent tissues, such as muscles and neurovascular bundles
Summary
Primary bone sarcomas are rare and represent about 0.2% of all malignant tumors in the general population [1], but about 5% of all primary malignant neoplasms in the pediatric population, with osteosarcoma and Ewing sarcoma being the most frequent in this group [2,3]. Radiomics has emerged as a process of extracting measurements and attributes from medical images that can generate relevant information for clinical decisions. The steps related to radiomics include the extraction of quantitative data from areas of interest in medical images, the storage of these data, and their use to generate and test clinical hypotheses [5]. Semiautomatic segmentation uses software algorithms that process initial data provided manually and creates a label with the possibility of manual editing of the result. Automatic segmentation does not Manual and semiautomatic segmentation of bone sarcomas need any information to be provided manually and creates labels based only on the image provided, with the possible inclusion of predetermined parameters and prior training. Segmentation is an essential step in radiomics, but it is important that segmentation is accurate and reproducible [7]
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