Add EmbeddingCollapseMetric: detect representational collapse in medical imaging embeddings

Closes #8808

Signed-off-by: ekansh-arora0 <ekansh.arora0@gmail.com>

Author: ekansh-arora0

docs/source/metrics.rst

@@ -158,6 +158,13 @@ Metrics
 
 `Fréchet Inception Distance`
 ------------------------------
+`Embedding Collapse`
+------------------------------
+.. autofunction:: compute_embedding_collapse
+
+.. autoclass:: EmbeddingCollapseMetric
+    :members:
+
 .. autofunction:: compute_frechet_distance
 
 .. autoclass:: FIDMetric

monai/metrics/__init__.py

@@ -16,6 +16,7 @@
 from .calibration import CalibrationErrorMetric, CalibrationReduction, calibration_binning
 from .confusion_matrix import ConfusionMatrixMetric, compute_confusion_matrix_metric, get_confusion_matrix
 from .cumulative_average import CumulativeAverage
+from .embedding_collapse import EmbeddingCollapseMetric, compute_embedding_collapse
 from .f_beta_score import FBetaScore
 from .fid import FIDMetric, compute_frechet_distance
 from .froc import compute_fp_tp_probs, compute_fp_tp_probs_nd, compute_froc_curve_data, compute_froc_score