Technical Note: An IBEX adaption toward image biomarker standardization

Abstract

Purpose Interest in the field of radiomics is rapidly growing because of its potential to characterize tumor phenotype and provide predictive and prognostic information. Nevertheless, the reproducibility and robustness of radiomics studies are hampered by the lack of standardization in feature definition and calculation. In the context of the image biomarker standardization initiative (IBSI), we investigated the grade of compliance of the image biomarker explorer (IBEX), a free open‐source radiomic software, and we developed and validated standardized‐IBEX (S‐IBEX), an adaptation of IBEX to IBSI. Methods Image biomarker explorer source code was checked against IBSI standard. Both the feature implementation and the overall image preprocessing chain were evaluated. Sections were re‐implemented wherever differences emerged: in particular, contour‐to‐binary‐mask conversion, image sub‐portion extraction, re‐segmentation, gray‐level discretization and interpolation were aligned to IBSI. All reported IBSI features were implemented in S‐IBEX. On a patient phantom, S‐IBEX was validated by benchmarking five different preprocessing configurations proposed by IBSI. Results Most IBEX feature definitions are IBSI compliant; however, IBEX preprocessing introduces non‐negligible nonconformities, resulting in feature values not aligned with the corresponding IBSI benchmarks. On the contrary, S‐IBEX features are in agreement with the standard regardless of preprocessing configurations: the percentage of features equal to their benchmark values ranges from 98.1% to 99.5%, with overall maximum percentage error below 1%. Moreover, the impact of noncompliant preprocessing steps has been assessed: in these cases, the percentage of features equal to the standard drops below 35%. Conclusions The use of standardized software for radiomic feature extraction is essential to ensure the reproducibility of results across different institutions, easing at the same time their external validation. This work presents and validates S‐IBEX, a free IBSI‐compliant software, developed upon IBEX, for feature extraction that is both easy to use and quantitatively accurate.

MRI-Based Radiomics to Differentiate between Benign and Malignant Parotid Tumors With External Validation

“…The extraction of the radiomic features was performed using S-IBEX software ( 14 ). S-IBEX is a standardized version of IBEX (image biomarker explorer) software ( 15 ) that was recently adapted and validated according to the guidelines of the Image Biomarker Standardization Initiative (IBSI) ( 16 ).…”

The Era of Radiogenomics in Precision Medicine: An Emerging Approach to Support Diagnosis, Treatment Decisions, and Prognostication in Oncology

“…These extracted quantitative data reflect the crucial part of the establishment of radiomics prediction models. In practice, 50 to 5,000 radiomic features processed by specific software, including PyRadiomics ( 32 , 33 ), CERR ( 34 , 35 ) or IBEX ( 36 , 37 ), are usually divided into morphological, intensity-based, and dynamic features ( 14 ) ( Figure 2 ). Morphology-based features can collect three-dimensional (3D) shape characteristics, including volume, surface area, and sphericity.…”

The Prognostic Value of Radiomics Features Extracted From Computed Tomography in Patients With Localized Clear Cell Renal Cell Carcinoma After Nephrectomy

“…Finally, 486 radiomics features were extracted from nephrographic, corticomedullary and unenhanced phase, including gray-level co-occurrence matrix (GLCM), gray-level run length matrix (GLRLM), shape, gradient orient histogram (GOH), neighbor intensity difference (NID), and intensity histogram. Most definitions of IBEX feature are compliant with Image Biomarkers Standardization Initiative (IBSI) ( 21 ).…”