Figure 4:

Learning anatomical representations $\beta$ with contrastive learning. $p_q,p_{+}$, and $p_{-}^{(n)}$ are query patch, positive patch, and negative patches, respectively. In previous works, $p_q$ is encouraged to be equal to $p_{+}$. In our work, $p_q$ is encouraged to be more similar to $p_{+}$ than to $p_{-}^{(n)}$ using Eq. 1, where $n=\{1,\dots ,N\}$ and $N$ is the number of negative patches.