diff --git a/src/modality-specific-files/magnetic-resonance-imaging-data.md b/src/modality-specific-files/magnetic-resonance-imaging-data.md
index 7099836c40..0015df6d13 100644
--- a/src/modality-specific-files/magnetic-resonance-imaging-data.md
+++ b/src/modality-specific-files/magnetic-resonance-imaging-data.md
@@ -162,6 +162,18 @@ A guide for using macros can be found at
 -->
 {{ MACROS___make_sidecar_table("mri.MRIEchoPlanarImagingAndB0Mapping") }}
 
+#### Tissue description
+
+<!-- This block generates a metadata table.
+These tables are defined in
+  src/schema/rules/sidecars
+The definitions of the fields specified in these tables may be found in
+  src/schema/objects/metadata.yaml
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_sidecar_table("mri.MRISample") }}
+
 ## Anatomy imaging data
 
 Anatomy MRI sequences measure static, structural features of the brain.
diff --git a/src/modality-specific-files/positron-emission-tomography.md b/src/modality-specific-files/positron-emission-tomography.md
index c16d144b4f..b63007ba10 100644
--- a/src/modality-specific-files/positron-emission-tomography.md
+++ b/src/modality-specific-files/positron-emission-tomography.md
@@ -216,6 +216,18 @@ A guide for using macros can be found at
 
 {{ MACROS___make_sidecar_table("pet.PETInstitutionInformation") }}
 
+#### Tissue description
+
+<!-- This block generates a metadata table.
+These tables are defined in
+  src/schema/rules/sidecars
+The definitions of the fields specified in these tables may be found in
+  src/schema/objects/metadata.yaml
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_sidecar_table("pet.PETSample") }}
+
 #### Task
 
 If the OPTIONAL [`task-<label>`](../appendices/entities.md#task) is used,
diff --git a/src/schema/rules/sidecars/mri.yaml b/src/schema/rules/sidecars/mri.yaml
index 63e4a900df..cb67a1bbcb 100644
--- a/src/schema/rules/sidecars/mri.yaml
+++ b/src/schema/rules/sidecars/mri.yaml
@@ -35,6 +35,14 @@ MRIHardware:
     MatrixCoilMode: recommended
     CoilCombinationMethod: recommended
 
+MRISample:
+  selectors:
+    - modality == "mri"
+  fields:
+    BodyPart: optional
+    BodyPartDetails: optional
+    BodyPartDetailsOntology: optional
+
 MRIScannerHardwareASL:
   selectors:
     - datatype == "perf"
diff --git a/src/schema/rules/sidecars/pet.yaml b/src/schema/rules/sidecars/pet.yaml
index 353389de71..bf2095b1ed 100644
--- a/src/schema/rules/sidecars/pet.yaml
+++ b/src/schema/rules/sidecars/pet.yaml
@@ -35,6 +35,17 @@ PETInstitutionInformation:
       level: recommended
       description_addendum: Corresponds to DICOM Tag 0008, 1040 `Institutional Department Name`.
 
+PETSample:
+  selectors:
+    - modality == "pet"
+    - suffix == "pet"
+  fields:
+    BodyPart:
+      level: recommended
+      description_addendum: Corresponds to DICOM Tag 0018, 0015 `Body Part Examined`.
+    BodyPartDetails: optional
+    BodyPartDetailsOntology: optional
+
 PETRadioChemistry:
   selectors:
     - modality == "pet"