ComputeM0 (Preclinical)
=======================

**Purpose.** Compute M0 from control series: ``Mat0 = mean(ImageCtr) / (1 - exp(-TR/T1t))``.

Context I/O
-----------

- **Reads:** ``ImageCtr`` (X,Y,Z,NR), ``Para`` (expects ``tr``), ``savedir``
- **Writes:** ``Mat0``; saves ``M0.npy`` and ``M0.png`` mosaic.

Parameters
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=================  ===================  ==========================================
Key                Type / Default       Meaning
=================  ===================  ==========================================
``T1t``            float / ``1900.0``   Tissue T1 (ms)
``TR``             float/"from_meta"    Use meta ``Para["tr"]`` or override with number
=================  ===================  ==========================================

YAML example
------------

.. code-block:: yaml

    modules:
      - name: ComputeM0
        params:
          T1t: 1900.0
          TR: from_meta