Final submission closed; results are in progress
Final evaluation is underway
The final challenge submission deadline closed on July 22, 2026. The organizing team is completing the final evaluation, and the final leaderboard is expected to be released around August 21, no later than August 23, 2026.
Pre-evaluation leaderboard
Review the published pre-evaluation results on Synapse while final evaluation is being completed.
MedReason individual method paper track
Following many requests from participating teams, MedReason has opened an optional archival paper track for all registered teams—not only the Top 3. Accepted papers will be included in the MICCAI 2026 Springer LNCS proceedings.
We sincerely apologize for the short notice, and we warmly encourage interested teams to submit an individual paper describing their team’s work.
Why MedReason?
MedReason evaluates whether medical MLLM systems can perform clinically grounded visual question answering when image quality and acquisition conditions shift.
The challenge builds on Med-CMR and focuses on one medical VQA task, while extending evaluation to more difficult out-of-distribution settings such as low-dose X-ray and 7T brain MRI.
The central question is not only whether a model can answer correctly, but whether its reasoning remains reliable, visually grounded, and robust under domain shift.
At-a-glance challenge task
Participants build one medical multimodal system for two question formats: multiple-choice and open-ended questions grounded in medical imaging evidence.
What the system receives
One medical image, one question, and optional context depending on the case.
What the system must return
For multiple-choice questions, the system returns one option. For open-ended questions, the system returns both a reasoning_trace and a final answer.
How performance is evaluated
Official ranking is based on MCQ Accuracy, Open-ended GT, and Open-ended VA, with organizer-side evaluation on hidden public and private evaluation datasets that contribute equally to the final ranking.
Challenge timeline
The challenge follows a simple progression: registration and data release → pre-evaluation → final submission and workshop.
Launch and registration
Website and registration open on Apr 22, 2026.
Train release
Public materials and train split are released on Apr 22, 2026.
Validation release
Participant-facing validation resources open on May 15, 2026.
Pre-evaluation submission
Pre-evaluation submissions are accepted until Jul 15, 2026. New teams may submit before this date, with one organizer-side pre-evaluation opportunity per team.
Final submission
The final Docker submission deadline closed on Jul 22, 2026.
Final evaluation and leaderboard
Final evaluation is in progress. The final leaderboard is expected to be released around Aug 16, 2026.
MICCAI workshop
The MedReason workshop activities will take place during MICCAI 2026.