Sophie Ostmeier

I am a CS master's student and research assistant at Stanford University, where I work at the AIMI Center.

From 2023 to 2025 I was funded by the German Research Foundation (DFG). Before Stanford, I completed an M.D. and Dr.med. at the Technical University of Munich.

Outside the lab you will find me running, cycling, bikepacking, swimming, playing pickleball, or hiking. I follow a wide range of sports—especially tennis, triathlon, and track & field—but I can appreciate almost any activity with movement.

Email  /  Google Scholar  /  Stanford Profile  /  Github  /  LinkedIn

profile photo

Research

My research focuses on how machine-learning models learn, make predictions and how we measure that, with a current emphasis on vision and/or language models. I am also curious about reinforcement learning as a path toward intelligent decision-making systems and wonder how they would do medicine.

Some recent papers (Google Scholar)

LieRE: Lie Rotational Positional Encodings
Sophie Ostmeier, Brian Axelrod, Maya Varma, Michael Moseley, Akshay Chaudhari, Curtis Langlotz,
ICML, 2025 / arXiv

We extend the rotational positional encodings widely used in large language models to high-dimensional rotation matrices by exploiting their Lie-group structure, and we test this approach on both 2-D and 3-D vision tasks.

GREEN: Generative Radiology Report Evaluation and Error Notation
Sophie Ostmeier,Justin Xu, Zhihong Chen, Maya Varma, Louis Blankemeier, Christian Bluethgen, Arne Edward Michalson, Michael Moseley, Curtis Langlotz, Akshay Chaudhari, Jean-Benoit Delbrouck,
EMNLP, Findings, 2024
project website / data / model

We present GREEN, an open-source metric that employs language models to spot and explain clinically significant errors in radiology reports, yielding expert-aligned scores, interpretable feedback, and commercial-grade performance.

USE-Evaluator: Performance metrics for medical image segmentation models supervised by uncertain, small or empty reference annotations
Sophie Ostmeier, Brian Axelrod, Fabian Isensee, Jeroen Bertels, Michael Mlynash, Soren Christensen, Maarten G Lansberg, Gregory W Albers, Rajen Sheth, Benjamin FJ Verhaaren, Abdelkader Mahammedi, Li-Jia Li, Greg Zaharchuk, Jeremy J Heit
Medical Image Analysis, 2023
arXiv / code

We investigate evaluation metrics for medical image segmentation that account for uncertainty, small structures, and empty reference annotations.

Miscellaneous

Academic Service

Co-Organizer, MICCAI 2025 Workshop on Multimodal LLMs in clinical Practice

Teaching

Lecturer, Stanford BioE 224, "AI in medical imaging" (2024, 2025)

Website Template source code.