Felix Ambellan

Mr. Felix Ambellan

Zuse-Institute-Berlin
orcid

Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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24 July 2019
Verified
Book Chapter
Closed access
PDF file
Felix AmbellanFelix Ambellan
Felix Ambellan
HLHans Lamecker
Hans Lamecker
CTChristoph von Tycowicz
Christoph von Tycowicz
SZStefan Zachow
Stefan Zachow

1 January 2018 in Medical Image Analysis
Verified
Journal Article
Closed access
CTChristoph Von Tycowicz
Christoph Von Tycowicz
Felix AmbellanFelix Ambellan
Felix Ambellan
AMAnirban Mukhopadhyay
Anirban Mukhopadhyay
SZStefan Zachow
Stefan Zachow

21 October 2021 in PLOS ONE
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Journal Article
Open access
PDF file
ATAlexander Tack
Alexander Tack
Felix AmbellanFelix Ambellan
Felix Ambellan
SZStefan Zachow
Stefan Zachow
Convolutional neural networks (CNNs) are the state-of-the-art for automated assessment of knee osteoarthritis (KOA) from medical image data. However, these methods lack interpretability, mainly focus on image texture, and cannot completely grasp the analyzed anatomies’ shapes. In this study we assess the informative value of quantitative features derived from segmentations in order to assess their potential as an alternative or extension to CNN-based approaches regarding multiple aspects of KOA. Six anatomical structures around the knee (femoral and tibial bones, femoral and tibial cartilages, and both menisci) are segmented in 46,996 MRI scans. Based on these segmentations, quantitative features are computed, i.e., measurements such as cartilage volume, meniscal extrusion and tibial coverage, as well as geometric features based on a statistical shape encoding of the anatomies. The feature quality is assessed by investigating their association to the Kellgren-Lawrence grade (KLG), joint space narrowing (JSN), incident KOA, and total knee replacement (TKR). Using gold standard labels from the Osteoarthritis Initiative database the balanced accuracy (BA), the area under the Receiver Operating Characteristic curve (AUC), and weighted kappa statistics are evaluated. Features based on shape encodings of femur, tibia, and menisci plus the performed measurements showed most potential as KOA biomarkers. Differentiation between non-arthritic and severely arthritic knees yielded BAs of up to 99%, 84% were achieved for diagnosis of early KOA. Weighted kappa values of 0.73, 0.72, and 0.78 were achieved for classification of the grade of medial JSN, lateral JSN, and KLG, respectively. The AUC was 0.61 and 0.76 for prediction of incident KOA and TKR within one year, respectively. Quantitative features from automated segmentations provide novel biomarkers for KLG and JSN classification and show potential for incident KOA and TKR prediction. The validity of these features should be further evaluated, especially as extensions of CNN-based approaches. To foster such developments we make all segmentations publicly available together with this publication.

1 October 2021 in Medical Image Analysis
Verified
Journal Article
Closed access
Felix AmbellanFelix Ambellan
Felix Ambellan
SZStefan Zachow
Stefan Zachow
CTChristoph Von Tycowicz
Christoph Von Tycowicz

10 October 2019
Verified
Book Chapter
Closed access
PDF file
Felix AmbellanFelix Ambellan
Felix Ambellan
SZStefan Zachow
Stefan Zachow
CTChristoph Von Tycowicz
Christoph Von Tycowicz