Abstract | OBJECTIVES: METHODS: Twenty-two radiologists (5 rectal MRI experts, 17 general/abdominal radiologists) retrospectively reviewed the post- chemoradiotherapy MRIs of 90 patients, scanned at 10 centers (with non-standardized protocols). They applied four response methods; two based on T2W-MRI only (MRI tumor regression grade (mrTRG); split- scar sign), and two based on T2W-MRI+DWI (modified-mrTRG; DWI-patterns). Image quality was graded using a 0-6-point score (including slice thickness and in-plane resolution; sequence angulation; DWI b-values, signal-to-noise, and artefacts); scores < 4 were classified below average. Mixed model linear regression was used to calculate average sensitivity/specificity/accuracy to predict a complete response (versus residual tumor) and assess the impact of reader experience and image quality. Group interobserver agreement ( IOA) was calculated using Krippendorff's alpha. Readers were asked to indicate their preferred scoring method(s). RESULTS: Average sensitivity/specificity/accuracy was 57%/64%/62% (mrTRG), 36%/79%/66% (split- scar), 40%/79%/67% (modified-mrTRG), and 37%/82%/68% (DWI-patterns); mrTRG showed higher sensitivity but lower specificity and accuracy (p < 0.001) compared to the other methods. IOA was lower for the split scar method (0.18 vs. 0.39-0.43). Higher reader experience had a significant positive effect on diagnostic performance and IOA (except for the split scar sign); below-average imaging quality had a significant negative effect on diagnostic performance. DWI pattern was selected as the preferred method by 73% of readers. CONCLUSIONS: Methods incorporating DWI showed the most favorable results when combining diagnostic performance, IOA, and reader preference. Reader experience and image quality clearly impacted diagnostic performance emphasizing the need for state-of-the-art imaging and dedicated radiologist training. KEY POINTS: • In a multireader study comparing 4 MRI methods for rectal tumor response evaluation, those incorporating DWI showed the best results when combining diagnostic performance, IOA, and reader preference. • The most preferred method (by 73% of readers) was the "DWI patterns" approach with an accuracy of 68%, high specificity of 82%, and group IOA of 0.43. • Reader experience level and MRI quality had an evident effect on diagnostic performance and IOA.
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Authors | Najim El Khababi, Regina G H Beets-Tan, Renaud Tissier, Max J Lahaye, Monique Maas, Luís Curvo-Semedo, Raphaëla C Dresen, Stephanie Nougaret, Geerard L Beets, Doenja M J Lambregts, rectal MRI study group |
Journal | European radiology
(Eur Radiol)
Vol. 33
Issue 6
Pg. 4367-4377
(Jun 2023)
ISSN: 1432-1084 [Electronic] Germany |
PMID | 36576549
(Publication Type: Multicenter Study, Journal Article)
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Copyright | © 2022. The Author(s), under exclusive licence to European Society of Radiology. |
Topics |
- Humans
- Diffusion Magnetic Resonance Imaging
(methods)
- Cicatrix
(pathology)
- Retrospective Studies
- Magnetic Resonance Imaging
(methods)
- Rectal Neoplasms
(diagnostic imaging, therapy)
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