  Segmentation is often the first step in many medical image analyses
workflows. Deep learning approaches, while giving state-of-the-art accuracies,
are data intensive and do not scale well to low data regimes. We introduce Deep
Conditional Shape Models 2.0, which uses an edge detector, along with an
implicit shape function conditioned on edge maps, to leverage cross-modality
shape information. The shape function is trained exclusively on a source domain
(contrasted CT) and applied to the target domain of interest (3D
echocardiography). We demonstrate data efficiency in the target domain by
varying the amounts of training data used in the edge detection stage. We
observe that DCSM 2.0 outperforms the baseline at all data levels in terms of
Hausdorff distances, and while using 50% or less of the training data in terms
of average mesh distance, and at 10% or less of the data with the dice
coefficient. The method scales well to low data regimes, with gains of up to 5%
in dice coefficient, 2.58 mm in average surface distance and 21.02 mm in
Hausdorff distance when using just 2% (22 volumes) of the training data.
