.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "generated/gallery/10-gradient-echo/gre_multiecho2D_sequence.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` to download the full example code. .. rst-class:: sphx-glr-example-title .. _sphx_glr_generated_gallery_10-gradient-echo_gre_multiecho2D_sequence.py: ======================================= 2D Cartesian multi-echo gradient echo ======================================= A spoiled low-flip-angle excitation is followed by several Cartesian gradient echoes of the same phase-encode line. Gradient and RF spoiling suppress residual transverse coherence before the next TR. The echo train samples T2* decay while TR and flip angle determine the T1 weighting. Multi-echo GRE is used for T2*/R2* mapping, susceptibility mapping, and structural imaging. .. GENERATED FROM PYTHON SOURCE LINES 12-32 .. GENERATED FROM PYTHON SOURCE LINES 33-38 Four-echo train --------------- Four echoes after each excitation, with readout gradients of alternating polarity. .. GENERATED FROM PYTHON SOURCE LINES 38-48 .. code-block:: Python import pypulseqpp as pp from pypulseqpp.sequences import gre_multiecho2D_sequence baseline = gre_multiecho2D_sequence( n_x=192, n_y=192, n_slices=1, n_echoes=4, te=None, tr=None, n_dummy=0 ) print(f"{baseline.num_blocks} blocks, {baseline.duration()[0]:.2f} s") print("TE", [round(t * 1e3, 2) for t in baseline.get_definition("TE")], "ms") .. rst-class:: sphx-glr-script-out .. code-block:: none 2112 blocks, 4.54 s TE [4.02, 8.7, 13.38, 18.06] ms .. GENERATED FROM PYTHON SOURCE LINES 49-51 Sequence diagram ---------------- .. GENERATED FROM PYTHON SOURCE LINES 51-54 .. code-block:: Python baseline.paper_plot() .. image-sg:: /generated/gallery/10-gradient-echo/images/sphx_glr_gre_multiecho2D_sequence_001.png :alt: gre multiecho2D sequence :srcset: /generated/gallery/10-gradient-echo/images/sphx_glr_gre_multiecho2D_sequence_001.png :class: sphx-glr-single-img .. GENERATED FROM PYTHON SOURCE LINES 55-60 Sampling order -------------- Colour encodes acquisition order. The echoes of one excitation sample the same phase-encode line. .. GENERATED FROM PYTHON SOURCE LINES 60-63 .. code-block:: Python pp.plot.plot_kspace(baseline, color_by="order", plane="xy", show_trajectory=False) .. image-sg:: /generated/gallery/10-gradient-echo/images/sphx_glr_gre_multiecho2D_sequence_002.png :alt: gre multiecho2D sequence :srcset: /generated/gallery/10-gradient-echo/images/sphx_glr_gre_multiecho2D_sequence_002.png :class: sphx-glr-single-img .. GENERATED FROM PYTHON SOURCE LINES 64-69 A longer echo train ------------------- Additional echoes extend the sampled decay curve and increase the minimum repetition time and final echo time. .. GENERATED FROM PYTHON SOURCE LINES 69-83 .. code-block:: Python alternative = gre_multiecho2D_sequence( n_x=192, n_y=192, n_slices=1, n_echoes=8, te=None, tr=None, n_dummy=0 ) .. rst-class:: sphx-glr-script-out .. code-block:: none blocks duration (s) acquisitions 4 echoes 2112 4.54 768 8 echoes 3648 8.13 1536 .. GENERATED FROM PYTHON SOURCE LINES 84-86 .. code-block:: Python pp.plot.plot_kspace(alternative, color_by="order", plane="xy", show_trajectory=False) .. image-sg:: /generated/gallery/10-gradient-echo/images/sphx_glr_gre_multiecho2D_sequence_003.png :alt: gre multiecho2D sequence :srcset: /generated/gallery/10-gradient-echo/images/sphx_glr_gre_multiecho2D_sequence_003.png :class: sphx-glr-single-img .. rst-class:: sphx-glr-timing **Total running time of the script:** (0 minutes 24.333 seconds) .. _sphx_glr_download_generated_gallery_10-gradient-echo_gre_multiecho2D_sequence.py: .. only:: html .. container:: sphx-glr-footer sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: gre_multiecho2D_sequence.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: gre_multiecho2D_sequence.py ` .. container:: sphx-glr-download sphx-glr-download-zip :download:`Download zipped: gre_multiecho2D_sequence.zip ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_