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Article

Stability of Radiomic Features across Different Region of Interest Sizes—A CT and MR Phantom Study

Department of Radiology, Corporate Member of Freie Universität and Humboldt-Universität zu Berlin, Charité–Universitätsmedizin Berlin, Hindenburgdamm 30, 12203 Berlin, Germany
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Author to whom correspondence should be addressed.
Academic Editor: Brian D. Ross
Received: 10 April 2021 / Revised: 19 May 2021 / Accepted: 3 June 2021 / Published: 8 June 2021
We aimed to evaluate radiomic features’ stability across different region of interest (ROI) sizes in CT and MR images. We chose a phantom with a homogenous internal structure so no differences for a feature extracted from ROIs of different sizes would be expected. For this, we scanned a plastic cup filled with sodium chloride solution ten times in CT and per MR sequence (T1-weighted-gradient-echo and T2-weighted-turbo-inversion-recovery-magnitude). We placed sphere-shaped ROIs of different diameters (4, 8, and 16 mm, and 4, 8, and 16 pixels) into the phantom’s center. Features were extracted using PyRadiomics. We assessed feature stability across ROI sizes with overall concordance correlation coefficients (OCCCs). Differences were tested for significance with the Mann–Whitney U-test. Of 93 features, 87 T1w-derived, 87 TIRM-derived, and 70 CT-derived features were significantly different between ROI sizes. Among MR-derived features, OCCCs showed excellent (>0.90) agreement for mean, median, and root mean squared for ROI sizes between 4 and 16 mm and pixels. We further observed excellent agreement for 10th and 90th percentile in T1w and 10th percentile in T2w TIRM images. There was no excellent agreement among the OCCCs of CT-derived features. In summary, many features indicated significant differences and only few showed excellent agreement across varying ROI sizes, although we examined a homogenous phantom. Since we considered a small phantom in an experimental setting, further studies to investigate this size effect would be necessary for a generalization. Nevertheless, we believe knowledge about this effect is crucial in interpreting radiomics studies, as features that supposedly discriminate disease entities may only indicate a systematic difference in ROI size. View Full-Text
Keywords: radiomics; texture analysis; magnetic resonance imaging; computed tomography; phantom; reproducibility; robustness radiomics; texture analysis; magnetic resonance imaging; computed tomography; phantom; reproducibility; robustness
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MDPI and ACS Style

Jensen, L.J.; Kim, D.; Elgeti, T.; Steffen, I.G.; Hamm, B.; Nagel, S.N. Stability of Radiomic Features across Different Region of Interest Sizes—A CT and MR Phantom Study. Tomography 2021, 7, 238-252. https://0-doi-org.brum.beds.ac.uk/10.3390/tomography7020022

AMA Style

Jensen LJ, Kim D, Elgeti T, Steffen IG, Hamm B, Nagel SN. Stability of Radiomic Features across Different Region of Interest Sizes—A CT and MR Phantom Study. Tomography. 2021; 7(2):238-252. https://0-doi-org.brum.beds.ac.uk/10.3390/tomography7020022

Chicago/Turabian Style

Jensen, Laura J., Damon Kim, Thomas Elgeti, Ingo G. Steffen, Bernd Hamm, and Sebastian N. Nagel 2021. "Stability of Radiomic Features across Different Region of Interest Sizes—A CT and MR Phantom Study" Tomography 7, no. 2: 238-252. https://0-doi-org.brum.beds.ac.uk/10.3390/tomography7020022

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