[ENH] BEP001 - RepetitionTimeExcitation and RepetitionTimePreparation

src/04-modality-specific-files/01-magnetic-resonance-imaging-data.md

@@ -194,6 +194,8 @@ fields specific to anatomical scans:
 | **Key name**            | **Requirement level** | **Data type** | **Description**                                                                                                                          |
 | ----------------------- | --------------------- | ------------- | ---------------------------------------------------------------------------------------------------------------------------------------- |
 | ContrastBolusIngredient | OPTIONAL              | [string][]    | Active ingredient of agent. Values MUST be one of: IODINE, GADOLINIUM, CARBON DIOXIDE, BARIUM, XENON Corresponds to DICOM Tag 0018,1048. |
+| RepetitionTimeExcitation | OPTIONAL              | [number][]    | The time in seconds between successive excitation pulses that excite a spin system. The DICOM tag that best refers to this parameter is [(0018, 0080)](http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0018,0080)). This field may be used together with the `RepetitionTimePreparation` for certain use cases, such as [MP2RAGE](https://infoscience.epfl.ch/record/172927/files/mp2rage.pdf). Use `RepetitionTimeExcitation` (in combination with `RepetitionTimePreparation` if needed) for anatomy imaging data rather than `RepetitionTime` as it is already defined as the amount of time that it takes to acquire a single volume in the [task imaging data](#task-including-resting-state-imaging-data) section.|
+| RepetitionTimePreparation | OPTIONAL              | [number][]    | The period of time in seconds that it takes a preparation pulse block to re-appear at the beginning of the succeeding (essentially identical) pulse sequence block. |
 
 Similarly, the OPTIONAL [`rec-<label>`](../99-appendices/09-entities.md#rec)
 key/value can be used to distinguish
@@ -290,7 +292,7 @@ JSON file.
 
 | **Key name**   | **Requirement level** | **Data type**            | **Description**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
 | -------------- | --------------------- | ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| RepetitionTime | REQUIRED              | [number][]               | The time in seconds between the beginning of an acquisition of one volume and the beginning of acquisition of the volume following it (TR). Please note that this definition includes time between scans (when no data has been acquired) in case of sparse acquisition schemes. This value needs to be consistent with the `pixdim[4]` field (after accounting for units stored in `xyzt_units` field) in the NIfTI header. This field is mutually exclusive with `VolumeTiming` and is derived from DICOM Tag 0018, 0080 and converted to seconds. |
+| RepetitionTime | REQUIRED              | [number][]               | The time in seconds between the beginning of an acquisition of one volume and the beginning of acquisition of the volume following it (TR). When used in the context of functional acquisitions this parameter best corresponds to [DICOM Tag 0020,0110](http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0020,0110)): the "time delta between images in a dynamic of functional set of images" but may also be found in [DICOM Tag 0018, 0080](http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0018,0080)): "the period of time in msec between the beginning of a pulse sequence and the beginning of the succeeding (essentially identical) pulse sequence". This definition includes time between scans (when no data has been acquired) in case of sparse acquisition schemes. This value MUST be consistent with the '`pixdim[4]`' field (after accounting for units stored in '`xyzt_units`' field) in the NIfTI header. This field is mutually exclusive with `VolumeTiming`. |
 | VolumeTiming   | REQUIRED              | [array][] of [numbers][] | The time at which each volume was acquired during the acquisition. It is described using a list of times referring to the onset of each volume in the BOLD series. The list must have the same length as the BOLD series, and the values must be non-negative and monotonically increasing. This field is mutually exclusive with `RepetitionTime` and `DelayTime`. If defined, this requires acquisition time (TA) be defined via either `SliceTiming` or `AcquisitionDuration` be defined.                                                         |
 | TaskName       | REQUIRED              | [string][]               | Name of the task. No two tasks should have the same name. The task label included in the file name is derived from this TaskName field by removing all non-alphanumeric (`[a-zA-Z0-9]`) characters. For example TaskName `faces n-back` will correspond to task label `facesnback`. A RECOMMENDED convention is to name resting state task using labels beginning with `rest`.                                                                                                                                                                       |