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morphometric analysis was drastically reduced,
since the user only has to select one single watershed
region.
Generally, best results were obtained in the first
two days of culture with lesser standard deviations.
High similarities between manual and semiautomatic
procedure were harder to get in the last two days of
culture, due to the increased number of peripheral
airway buds and complexity of lung architecture.
The standard deviation of the interactive method was
null after all researchers selected the same start
region to begin the merging process.
The segmentation rate depended on the number
of regions needed to be merged to select the entire
region lung epithelial. However, in all cases the
interactive segmentation time was less than the
manual one (34±7% of the manual time).
The merging procedure was essential to achieve
a good segmentation, since a lot of regions were
firstly created by a watershed algorithm.
Sometimes, the presented method produced
undermerged regions due to ambiguity and lack of
definition of the inner lung explants contours. These
cases increase the probability of merging dissimilar
regions and incoherence between boundaries of
some watershed regions and boundaries of lung
explants inner contours.
5 CONCLUSIONS
Regulating mechanisms of branching morphogenesis
of fetal lung rat explants have been an essential tool
for molecular research. The application of this work
provides a technique for lung rat explants
segmentation and analysis by selecting only one
watershed region belonging to the inner lung
epithelial. The total number of decisions, time-
consumption and user dependence were significantly
decreased.
Further work is needed regarding the merging
procedure and the development of image
enhancement techniques to improve inner lung
epithelial contrast, mainly in the last days of culture,
in order to decrease the standard deviation of results
and increase its reliability. Moreover, a new
algorithm must be developed for counting the
number of peripheral airway buds of lung explants.
ACKNOWLEDGEMENTS
The authors acknowledge to Foundation for Science
and Technology (FCT) - Portugal for the fellowships
with the references: SFRH/BD/74276/2010,
SFRH/BD/68270/2010, SFRH/BPD/46851/2008 and
SFRH/BD/51062/2010.
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