# Mammo-FM risk checkpoints: BU S1 KD + S2

This release contains five BU fold-specific **final Stage 2 risk models
initialized through Stage 1 MIRAI knowledge distillation**. It is the
historical `all_years/aug_n/from_stage1` model family, not Stage 1 alone and
not the S2-only comparison variant. These checkpoints replace the previously
released Mayo-labelled Stage 1/Stage 2 pair, which was not the intended BU
benchmark release.

## Download and provenance

All five files contain 184,831,762 bytes. Stored epoch values are reproduced
without changing their indexing convention. The
[release manifest](https://huggingface.co/batmanLab/Mammo-FM/blob/main/risk_checkpoints/BU_S1_KD_S2/manifest.json)
contains the same checkpoint identities and hashes.

| BU fold | Final S1 KD + S2 checkpoint | Stored epoch | SHA-256 |
| --- | --- | ---: | --- |
| 1 | [Download fold 1](https://huggingface.co/batmanLab/Mammo-FM/resolve/main/risk_checkpoints/BU_S1_KD_S2/fold1/Mammo-FM_BU_S1_KD_S2_fold1.pth-best.tar) | 2 | `f57730d674716c5870e5f0678c82c2a21cdff37eea518059f09809032830653e` |
| 2 | [Download fold 2](https://huggingface.co/batmanLab/Mammo-FM/resolve/main/risk_checkpoints/BU_S1_KD_S2/fold2/Mammo-FM_BU_S1_KD_S2_fold2.pth-best.tar) | 4 | `cac0884effa796de7fc32ac98b630301755d1d72a12a52addab24853a2c618a9` |
| 3 | [Download fold 3](https://huggingface.co/batmanLab/Mammo-FM/resolve/main/risk_checkpoints/BU_S1_KD_S2/fold3/Mammo-FM_BU_S1_KD_S2_fold3.pth-best.tar) | 6 | `f6b1cf5845c708a530ef8f5f98ecf2db87b54217f74b430e9b068ec99a40d1d6` |
| 4 | [Download fold 4](https://huggingface.co/batmanLab/Mammo-FM/resolve/main/risk_checkpoints/BU_S1_KD_S2/fold4/Mammo-FM_BU_S1_KD_S2_fold4.pth-best.tar) | 6 | `b1bf8769f3d6ee86253e36a473047396fb2e9d34470c440b8c5c4421dcbb9742` |
| 5 | [Download fold 5](https://huggingface.co/batmanLab/Mammo-FM/resolve/main/risk_checkpoints/BU_S1_KD_S2/fold5/Mammo-FM_BU_S1_KD_S2_fold5.pth-best.tar) | 5 | `0df00131c5a91ccd2e9d464bdbfb561f9604d589e38e61fa2903de5c50b8490f` |

```bash
hf download batmanLab/Mammo-FM \
  --include 'risk_checkpoints/BU_S1_KD_S2/*' \
  --local-dir /path/to/checkpoints
```

The weights are released byte-for-byte from the historical best-validation
checkpoints. Their payloads contain `model`, `optimizer`, `scheduler`, and
`epoch`; fold and training-stage lineage come from the corresponding original
experiment artifacts. No images, reports, patient-level tables, predictions,
feature caches, or API credentials are included. Store downloaded weights
and all experiment outputs outside the source repository.

## BU held-out evaluation

Checkpoint `fold{k}` must be evaluated only on source rows with
`split_fold_{k}=test_fold_{k}`. The five patient-disjoint test folds cover
13,694 examinations from 9,900 patients. They are not an ensemble; do not
apply one fold's model to the entire cohort or average the five models'
predictions for this benchmark.

Preserve the historical BU PNG preprocessing and the four-view order
`LMLO -> LCC -> RMLO -> RCC`, including its view/side metadata. A generic
Mayo-style DICOM loader is a different input pipeline and is not a drop-in
replacement for this benchmark.

The model returns raw, uncalibrated independent sigmoid probabilities for
years 1 through 5. AUROC and AUPRC (average precision) are evaluated within
each fold using horizon-specific follow-up masks and reported as unweighted
five-fold means. C-index is reported as the mean and between-fold standard
deviation. Do not replace these with pooled metrics, calibrated risks, or
monotonic/cumulative post-processing.

| Horizon | Eligible examinations | Positive examinations |
| --- | ---: | ---: |
| 1 year | 13,694 | 283 |
| 2 years | 12,724 | 495 |
| 3 years | 11,878 | 700 |
| 4 years | 11,113 | 888 |
| 5 years | 10,369 | 1,044 |

## Model loading

The historical model state registers the same encoder under
`image_encoder.*` and `aggregator.image_encoder.*`. The Mammo-FM compatibility
loader verifies exact equality of these duplicate tensors before removing
only the duplicate namespace. The complete remaining state must then be
loaded strictly.

Download the compatible base checkpoint for architecture construction:

```bash
hf download batmanLab/Mammo-FM Mammo-FM_BatmanlabTrained_CLIP.tar \
  --local-dir /path/to/checkpoints
```

The base checkpoint supplies the encoder architecture configuration. Loading
the full risk checkpoint replaces the encoder and all risk-model tensors;
the final predictions do not retain the base encoder's initialization.
Optimizer and scheduler states are not used for inference. Load serialized
training checkpoints only from a trusted source.

## Validation status and use restrictions

Historical checkpoint identity and ported-code numerical parity are separate
checks. Availability of these weights does not establish that the port has
reproduced the historical BU held-out predictions or metrics. The fold-matched
comparison must complete before such a claim is made.

The repository's model-weight license applies. The weights are for
non-commercial academic research only and must not be used for clinical
decisions.