C Dreher1, T A Kuder2, F König3, A Mlynarska-Bujny4, C Tenconi5, D Paech3, H-P Schlemmer3, M E Ladd6, S Bickelhaupt7. 1. University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Department of Radiation Oncology, Theodor Kutzer-Ufer 1-3, 68167, Mannheim, Germany; German Cancer Research Center (DKFZ), Division of Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. Electronic address: constantin.dreher@umm.de. 2. German Cancer Research Center (DKFZ), Division of Medical Physics in Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. 3. German Cancer Research Center (DKFZ), Division of Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. 4. German Cancer Research Center (DKFZ), Division of Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany; German Cancer Research Center (DKFZ), Division of Medical Physics in Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. 5. German Cancer Research Center (DKFZ), Division of Medical Physics in Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany; Università degli Studi di Milano, Department of Oncology and Hemato-oncology, Via Festa del Perdono 7, 20122, Milano, Italy. 6. German Cancer Research Center (DKFZ), Division of Medical Physics in Radiology, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany; Faculty of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany; Faculty of Medicine, University of Heidelberg, Heidelberg, Germany. 7. German Cancer Research Center (DKFZ), Medical Imaging and Radiology - Cancer Prevention, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany; Friedrich-Alexander-University Erlangen-Nürnberg, Institute of Radiology, Maximiliansplatz 2, 91054, Erlangen, Germany.
Abstract
AIM: The aim of this study was to evaluate the robustness of radiomics features of a MRI (magnetic resonance imaging) phantom in quantitative diffusion-weighted imaging (DWI) and depending on the image resolution. MATERIALS AND METHODS: Scanning of an in-house developed DWI phantom was performed at a 1.5 T MRI scanner (Magnetom AERA, Siemens, Erlangen, Germany) using an echo planar imaging (EPI) DWI sequence (b=0,500,1,000 s/mm2) with low (3×3 mm2) and high (2×2 mm2) image resolutions. Scans were repeated after phantom repositioning to evaluate retest reliability. Radiomics features were extracted after semi-automatic segmentation and standardised pre-processing. Intra-/interobserver reproducibility and test-retest robustness were assessed using intraclass correlation coefficients (ICC). Differences were tested with non-parametric Wilcoxon's signed-rank and Friedman's test (p < 0.05) with Dunn's post-hoc analysis. RESULTS: Test-retest ICC was overall high with >0.90 for 39/46 radiomics features in all sequences/resolutions. Decreased test-retest ICCs were pronounced for conventional Min-value (overall ICC=0.817), and grey-level zone length matrix (GLZLM) features Short-Zone Emphasis (SZE) and Short-Zone Low Grey-level Emphasis (SZLGE) (for both overall ICC=0.927). Test-retest reproducibility was significantly different between b=500, 1,000 and apparent diffusion coefficient (ADC) (mean 0.975±0.050, 0.974±0.051 and 0.966±0.063), which remained significant after post-hoc analysis between b=1,000 and ADC (p = 0.022). ICCs were not significantly different between resolutions of 2×2 and 3×3 mm2 regarding b=500 (mean: 0.977±0.052 and 0.974±0.049, p = 0.612), b=1,000 (mean: 0.973±0.059 and 0.974±0.054, p = 0.516), and ADC (mean: 0.972±0.049 and 0.955±0.101, p = 0.851). Inter- and intra-observer reliability was consistently high for all sequences (overall mean 0.992±0.021 and 0.990±0.028). CONCLUSION: Under ex-vivo conditions, DWI provided robust radiomics features with those from ADC being slightly less robust than from raw DWI (b=500, 1,000 s/mm2). No significant difference was detected for different resolutions. Although, ex-vivo reliability of DWI radiomics features was high, no implications can be made regarding in-vivo analyses.
AIM: The aim of this study was to evaluate the robustness of radiomics features of a MRI (magnetic resonance imaging) phantom in quantitative diffusion-weighted imaging (DWI) and depending on the image resolution. MATERIALS AND METHODS: Scanning of an in-house developed DWI phantom was performed at a 1.5 T MRI scanner (Magnetom AERA, Siemens, Erlangen, Germany) using an echo planar imaging (EPI) DWI sequence (b=0,500,1,000 s/mm2) with low (3×3 mm2) and high (2×2 mm2) image resolutions. Scans were repeated after phantom repositioning to evaluate retest reliability. Radiomics features were extracted after semi-automatic segmentation and standardised pre-processing. Intra-/interobserver reproducibility and test-retest robustness were assessed using intraclass correlation coefficients (ICC). Differences were tested with non-parametric Wilcoxon's signed-rank and Friedman's test (p < 0.05) with Dunn's post-hoc analysis. RESULTS: Test-retest ICC was overall high with >0.90 for 39/46 radiomics features in all sequences/resolutions. Decreased test-retest ICCs were pronounced for conventional Min-value (overall ICC=0.817), and grey-level zone length matrix (GLZLM) features Short-Zone Emphasis (SZE) and Short-Zone Low Grey-level Emphasis (SZLGE) (for both overall ICC=0.927). Test-retest reproducibility was significantly different between b=500, 1,000 and apparent diffusion coefficient (ADC) (mean 0.975±0.050, 0.974±0.051 and 0.966±0.063), which remained significant after post-hoc analysis between b=1,000 and ADC (p = 0.022). ICCs were not significantly different between resolutions of 2×2 and 3×3 mm2 regarding b=500 (mean: 0.977±0.052 and 0.974±0.049, p = 0.612), b=1,000 (mean: 0.973±0.059 and 0.974±0.054, p = 0.516), and ADC (mean: 0.972±0.049 and 0.955±0.101, p = 0.851). Inter- and intra-observer reliability was consistently high for all sequences (overall mean 0.992±0.021 and 0.990±0.028). CONCLUSION: Under ex-vivo conditions, DWI provided robust radiomics features with those from ADC being slightly less robust than from raw DWI (b=500, 1,000 s/mm2). No significant difference was detected for different resolutions. Although, ex-vivo reliability of DWI radiomics features was high, no implications can be made regarding in-vivo analyses.
Authors: R W Y Granzier; A Ibrahim; S Primakov; S A Keek; I Halilaj; A Zwanenburg; S M E Engelen; M B I Lobbes; P Lambin; H C Woodruff; M L Smidt Journal: J Magn Reson Imaging Date: 2021-12-22 Impact factor: 5.119
Authors: Renée W Y Granzier; Abdalla Ibrahim; Sergey P Primakov; Sanaz Samiei; Thiemo J A van Nijnatten; Maaike de Boer; Esther M Heuts; Frans-Jan Hulsmans; Avishek Chatterjee; Philippe Lambin; Marc B I Lobbes; Henry C Woodruff; Marjolein L Smidt Journal: Cancers (Basel) Date: 2021-05-18 Impact factor: 6.639