  We introduce CartiMorph, a framework for automated knee articular cartilage
morphometrics. It takes an image as input and generates quantitative metrics
for cartilage subregions, including the percentage of full-thickness cartilage
loss (FCL), mean thickness, surface area, and volume. CartiMorph leverages the
power of deep learning models for hierarchical image feature representation.
Deep learning models were trained and validated for tissue segmentation,
template construction, and template-to-image registration. We established
methods for surface-normal-based cartilage thickness mapping, FCL estimation,
and rule-based cartilage parcellation. Our cartilage thickness map showed less
error in thin and peripheral regions. We evaluated the effectiveness of the
adopted segmentation model by comparing the quantitative metrics obtained from
model segmentation and those from manual segmentation. The root-mean-squared
deviation of the FCL measurements was less than 8%, and strong correlations
were observed for the mean thickness (Pearson's correlation coefficient $\rho
\in [0.82,0.97]$), surface area ($\rho \in [0.82,0.98]$) and volume ($\rho \in
[0.89,0.98]$) measurements. We compared our FCL measurements with those from a
previous study and found that our measurements deviated less from the ground
truths. We observed superior performance of the proposed rule-based cartilage
parcellation method compared with the atlas-based approach. CartiMorph has the
potential to promote imaging biomarkers discovery for knee osteoarthritis.
