diff --git a/monai/data/image_reader.py b/monai/data/image_reader.py
index a85eb95c20..653078c5a4 100644
--- a/monai/data/image_reader.py
+++ b/monai/data/image_reader.py
@@ -735,9 +735,22 @@ def _get_affine(self, metadata: dict, lps_to_ras: bool = True):
             metadata: metadata with dict type.
             lps_to_ras: whether to convert the affine matrix from "LPS" to "RAS". Defaults to True.
 
+        Warns:
+            UserWarning: when ImageOrientationPatient (00200037) or ImagePositionPatient
+                (00200032) is missing from metadata. The affine matrix is set to identity,
+                which may be incorrect. Common with multiframe DICOM files.
+
         """
         affine: np.ndarray = np.eye(4)
         if not ("00200037" in metadata and "00200032" in metadata):
+            warnings.warn(
+                "PydicomReader: ImageOrientationPatient (00200037) or "
+                "ImagePositionPatient (00200032) not found in DICOM metadata. "
+                "The affine matrix will be set to identity, which may be incorrect. "
+                "This commonly occurs with multiframe DICOM files (e.g., Enhanced CT). "
+                "Consider using ITKReader for accurate spatial metadata.",
+                stacklevel=2,
+            )
             return affine
         # "00200037" is the tag of `ImageOrientationPatient`
         rx, ry, rz, cx, cy, cz = metadata["00200037"]["Value"]