Ning Bi

I am a Postdoctoral Researcher at the University of Oxford, working with NDS and IBME on generative AI for healthcare, digital contrast CT, and scalable CT foundation models. My current research develops diffusion-based image translation methods that synthesize contrast-enhanced CT from non-contrast scans, with attention to spatial priors, uncertainty modelling, and clinical usability.

I completed my PhD in Computer Science at the University of Leeds, supervised by Prof. Alejandro F. Frangi and Dr. Zeike Taylor. My doctoral work focused on Bayesian deep learning for cardiac motion modelling, deformable registration, and joint segmentation-motion estimation in cardiac MRI.

I received my BSc in Computer Science with First Class Honours from ShanghaiTech University, where I worked on computer vision, object detection, and visual tracking as part of the SVIP Lab.

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Research

My research sits at the intersection of medical image analysis, generative modelling, and foundation models for healthcare. I am especially interested in diffusion models, image-to-image translation, multimodal integration, uncertainty-aware learning, CT angiography, and cardiac MRI.

Current Digital Contrast and CT Foundation Models
Postdoctoral Researcher, University of Oxford
Nov. 2023 - Present

Developing and benchmarking generative models for contrast-enhanced CT synthesis from non-contrast CT. This work is connected to the NETZERO AICT consortium and broader efforts to build large-scale CT foundation models for scientific discovery and clinical translation.

Research Cardiac Motion Modelling and Medical Image Registration
PhD Research, University of Leeds
Sept. 2019 - Nov. 2023

Built probabilistic and deep learning methods for cardiac cine-MRI motion modelling, deformable registration, and concurrent segmentation-motion estimation.

Industry Scaling Laws and Sparsity in Large Language Models
Applied Science Intern, Amazon Web Services, Tuebingen, Germany
Jan. 2024 - May 2024

Investigated model scaling, sparsity, and pruning strategies for large language models, with a focus on efficiency-performance tradeoffs in foundation model development.

Selected Publications

* indicates equal contribution. A fuller and more current list is available on Google Scholar.

2026 AortaDiff: A Unified Multitask Diffusion Framework for Contrast-Free AAA Imaging
Y. Ou, N. Bi, J. Pan, J. Yang, B. Yu, U. Zidan, R. Lee, V. Grau
WACV, 2026
arXiv / code

A multitask conditional diffusion framework for synthetic contrast-enhanced CT generation and aortic structure segmentation.

2025 Deep Learning Models for Cardiomegaly Detection Enables Assessment of Cardiomegaly Prevalence in an International CT Data Repository: Insights from AICT Consortium
U. Zidan*, N. Bi*, A. Chandrashekar, M. Bown, E. Joviliano, V. Grau, E. R. Ranschaert, R. Lee
European Congress of Radiology, 2025   (Oral Presentation)

Consortium-scale CT analysis for cardiomegaly detection and prevalence assessment across an international imaging repository.

2024 SegMorph: Concurrent Motion Estimation and Segmentation for Cardiac MRI Sequences
N. Bi, A. Zakeri, Y. Xia, N. Cheng, A. F. Frangi, A. Gooya
IEEE Transactions on Medical Imaging, 2024
DOI / PubMed

A recurrent variational framework for concurrent segmentation and motion estimation in cardiac cine-MRI sequences.

2023 GSMorph: Gradient Surgery for cine-MRI Cardiac Deformable Registration
H. Dou*, N. Bi*, L. Han, Y. Huang, R. Mann, X. Yang, D. Ni, N. Ravikumar, A. F. Frangi, Y. Huang
MICCAI, 2023
arXiv / DOI / code

A hyperparameter-free deformable registration method using gradient surgery to balance registration accuracy and deformation smoothness.

2022 DragNet: Learning-Based Deformable Registration for Realistic Cardiac MR Sequence Generation from a Single Frame
A. Zakeri*, A. Hokmabadi*, N. Bi, I. Wijesinghe, M. G. Nix, S. E. Petersen, A. F. Frangi, Z. A. Taylor, A. Gooya
Medical Image Analysis, 2022

Learning-based deformable registration for generating realistic cardiac MR sequences from a single frame.

2020 Visual Tracking with Multiview Trajectory Prediction
M. Wu, H. Ling, N. Bi, S. Gao, Q. Hu, H. Sheng, J. Yu
IEEE Transactions on Image Processing, 2020
2019 PPGNet: Learning Point-Pair Graph for Line Segment Detection
Z. Zhang*, Z. Li*, N. Bi, S. Gao
CVPR, 2019
Experience
2023 - Present Postdoctoral Researcher
University of Oxford, NDS and IBME, Oxford, UK
2024 Applied Science Intern
Amazon Web Services, Tuebingen, Germany
2020 - 2023 Teaching Assistant
University of Leeds, Leeds, UK
Education
2019 - 2023 PhD in Computer Science
University of Leeds, School of Computing
Thesis: Bayesian Deep Learning for Cardiac Motion Modelling and Analysis
2015 - 2019 BSc in Computer Science, First Class Honours
ShanghaiTech University, School of Information Science and Technology
Skills and Service

Methods: diffusion models, Bayesian deep learning, image-to-image translation, deformable registration, multimodal data integration, uncertainty modelling, CT angiography, cardiac MRI.

Tools: Python, PyTorch, Hugging Face Transformers/Diffusers, MONAI, PyTorch Lightning, SciPy, scikit-learn, OpenCV, Pandas, Weights & Biases, Docker, Git, AWS, Microsoft Azure, Nibabel, ITK/SimpleITK, 3D Slicer.

Service and awards: reviewer for MICCAI, IEEE TMI, and IEEE TNNLS; Best Poster Award at the University of Leeds School of Computing Symposium; full PhD scholarship from the University of Leeds.