Diffeomorphic deformable multi-modal image registration is a challenging task
which aims to bring images acquired by different modalities to the same
coordinate space and at the same time to preserve the topology and the
invertibility of the transformation. Recent research has focused on leveraging
deep learning approaches for this task as these have been shown to achieve
competitive registration accuracy while being computationally more efficient
than traditional iterative registration methods. In this work, we propose a
simple yet effective unsupervised deep learning-based {\em multi-modal} image
registration approach that benefits from auxiliary information coming from the
gradient magnitude of the image, i.e. the image edges, during the training. The
intuition behind this is that image locations with a strong gradient are
assumed to denote a transition of tissues, which are locations of high
information value able to act as a geometry constraint. The task is similar to
using segmentation maps to drive the training, but the edge maps are easier and
faster to acquire and do not require annotations. We evaluate our approach in
the context of registering multi-modal (T1w to T2w) magnetic resonance (MR)
brain images of different subjects using three different loss functions that
are said to assist multi-modal registration, showing that in all cases the
auxiliary information leads to better results without compromising the runtime.

本文提出了一种基于无监督深度学习的多模态图像配准方法，该方法利用图像梯度幅度来作为辅助信息，通过三种不同的损失函数比较证明该方法能提升多模态配准的准确性且运行时间不受影响。

多模式非监督脑图像配准使用边缘地图

Multi-modal unsupervised brain image registration using edge maps

Automatic segmentation in MR brain images is important for quantitative
analysis in large-scale studies with images acquired at all ages.
This paper presents a method for the automatic segmentation of MR brain
images into a number of tissue classes using a convolutional neural network. To
ensure that the method obtains accurate segmentation details as well as spatial
consistency, the network uses multiple patch sizes and multiple convolution
kernel sizes to acquire multi-scale information about each voxel. The method is
not dependent on explicit features, but learns to recognise the information
that is important for the classification based on training data. The method
requires a single anatomical MR image only.
The segmentation method is applied to five different data sets: coronal
T2-weighted images of preterm infants acquired at 30 weeks postmenstrual age
(PMA) and 40 weeks PMA, axial T2- weighted images of preterm infants acquired
at 40 weeks PMA, axial T1-weighted images of ageing adults acquired at an
average age of 70 years, and T1-weighted images of young adults acquired at an
average age of 23 years. The method obtained the following average Dice
coefficients over all segmented tissue classes for each data set, respectively:
0.87, 0.82, 0.84, 0.86 and 0.91.
The results demonstrate that the method obtains accurate segmentations in all
five sets, and hence demonstrates its robustness to differences in age and
acquisition protocol.

使用卷积神经网络的多尺度信息，对单个解剖学 MR 图像进行自动分割，取得了在不同年龄和采集协议下的高度准确的分割结果。