OpenTalks.AI - Сергей Кастрюлин, Ускорение МРТ с помощью нейронных сетей

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February 21, 2020

OpenTalks.AI - Сергей Кастрюлин, Ускорение МРТ с помощью нейронных сетей

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OpenTalks.AI

February 21, 2020
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  1. © Philips - Confidential Nicola Pezzotti1, Elwin de Weerdt2, Sahar

    Yousefi3, Mohamed S. Elmahdy3, Jeroen van Gemert2, Christophe Schülke1, Mariya Doneva1, Tim Nielsen1, Sergey Kastryulin1, Boudewijn P.F. Lelieveldt3, Matthias J.P. van Osch3, Marius Staring3 1 Philips Research 2 Philips Healthcare 3 Leiden University Medical Center FastMRI with Adaptive Intelligence Best performer in the FastMRI challenge (NeurIPS 2019) multi-coil 4x and 8x
  2. © Philips - Confidential MRIs give a wealth of information…

    … but are slow (~20 min up to an hour)
  3. © Philips - Confidential data information From scanner to report

  4. © Philips - Confidential data information From scanner to report

  5. © Philips - Confidential The more data desire, the more

    data required Image reconstruction Raw data Image MRI scanner
  6. © Philips - Confidential Why so slow? Gathering data takes

    time
  7. © Philips - Confidential Why so slow? Gathering data takes

    time
  8. © Philips - Confidential Why so slow? Gathering data takes

    time
  9. © Philips - Confidential Why so slow? Gathering data takes

    time
  10. © Philips - Confidential Why so slow? Gathering data takes

    time
  11. © Philips - Confidential The more data desire, the more

    data required Image reconstruction Raw data Image
  12. © Philips - Confidential Learned reconstruction with a neural network

    Raw data Image
  13. © Philips - Confidential Three different challenges Single-Coil 4x Easier

    to experiment, simulated single coil measurement. Not used clinilcally. Multi-Coil 4x Clinically relevant, multiple coil measurements. ~2x faster than parallel imaging. Multi-Coil 8x Clinically relevant, multiple coil measurements. ~4x faster than parallel imaging.
  14. © Philips - Confidential Realistic scenario vs ease of experimentation

    Almost all MRI scanners use technique called “parallel imaging” that uses multiple Receiver coils in order to capture information from different spatial locations. This can speed up scanning process by ~2x.
  15. © Philips - Confidential Evaluation Stage 1 SSIM (Structural Similarity

    Index Metric) measures the perceived change in structural information between two images. As with other quantitative metrics, may not capture qualitative differences perceived by radiologists. Stage 2 Top 4 entries as scored by SSIM are ranked by 7 radiologists. Winners determined by the best average radiologist ranking.
  16. © Philips - Confidential Baseline provided by organizers IFFT U-Net

  17. © Philips - Confidential Adaptive CS-Network A Deep Learning solution

    that integrates Compressed-Sensing theory
  18. © Philips - Confidential Compressed Sensing for MR reconstruction 18

    Iteration n Iteration n+1 Initial Image Intermediate Final Image F(): Sparsifying transform F-1(): Invert Sparsification Thresholding Function Thresholding Function Wavelet decomposition Wavelet decomposition
  19. © Philips - Confidential Adaptive CS-Network Combination of Compressed-Sensing theory

    and Deep-Learning Iterative AI-Based Compressed-Sensing approach + + + + + Iterative – Multiscale – MR Physics •
  20. © Philips - Confidential Adaptive CS-Network " . $ "

    . " . Filtered-UNet • UNet-like design • Each feature map is filtered • Only basic DL operations to retain control • Convolution 2D without bias term • Leaky ReLU • Max pooling • Interpolation 2D • 2.5D Convolutions • Loss applied to the central slice only " . $ " . " .
  21. © Philips - Confidential Adaptive CS-Network ' ( ) "*(

    " ' . ( . " . " . $ " . " . " "*( Deep-Learning Based
  22. © Philips - Confidential Adaptive CS-Network ' ( ) "*(

    " ' . ( . " . -," / -0 - (" , ) / (" ) -0 (" ) " . $ " . " . " "*( + Deep-Learning Based MR-Specific Knowledge
  23. © Philips - Confidential Loss function definition Multiscale-SSIM We adopted

    a mixed approach Loss =0.86 * MSSSIM + 0.14 * L1 • Better results reported in literature • Higher SSIM metric • Less artifacts in the image
  24. © Philips - Confidential Loss function definition Panels of diverse

    reconstructions were shown to radiologists and clinical scientists
  25. © Philips - Confidential Winners Single-coil 4x University of Amsterdam

    Multi-coil 4x United Imaging Intelligence/John Hopkins University Philips Multi-coil 8x Philips
  26. © Philips - Confidential Zero Filled Reconstruction Ground-truth Volume: 1000108

    – Effective acceleration: 3.64x – SSIM: 0.9885
  27. © Philips - Confidential Zero Filled Reconstruction Ground-truth Volume: 1002340

    – Effective acceleration: 9.68x – SSIM: 0.8254
  28. © Philips - Confidential Conclusion • Improvement over compressed-sensing is

    within reach • Importance to involve Radiologist and Clinical Scientist • To design loss functions • To evaluate results • Importance of combining prior-knowledge in Deep- Learning solutions • Compressed sensing • MR Physics Paper from NeurIPS’19: https://arxiv.org/abs/1912.12259
  29. © Philips - Confidential The Team

  30. © Philips - Confidential Nicola Pezzotti1, Elwin de Weerdt2, Sahar

    Yousefi3, Mohamed S. Elmahdy3, Jeroen van Gemert2, Christophe Schülke1, Mariya Doneva1, Tim Nielsen1, Sergey Kastryulin1, Boudewijn P.F. Lelieveldt3, Matthias J.P. van Osch3, Marius Staring3 1 Philips Research 2 Philips Healthcare 3 Leiden University Medical Center Q&A