Improving Segmentation of Breast Ultrasound
Images: Semi Automatic Two Pointers Histogram
Splitting Technique
Rasheed Abid
Biomedical engineering
Illinois Institute of Technology
Chicago, IL, USA
r.abid94.bogra@gmail.com
S. Kaisar Alam
Rutgers University
Newark, NJ,USA
kaisar.alam@ieee.org
Abstract—Automatically segmenting lesion area in breast ul-
trasound (BUS) images is a challenging one due to its noise,
speckle and artifacts. Edge-map of BUS images also does not
help because in most cases the edge-map gives no information
whatsoever. Almost all segmentation technique takes the edge-
map of the image as its first step, though there are a few
algorithms that try to avoid edge-maps as well. Improving the
edge-map of breast ultrasound images theoretically improves
the chances of automatic segmentation to be more precise. In
this paper, we propose a semi-automatic technique of histogram
splitting using two pointers. Here the user only has to select
two initially guessed points denoting a circle on the region of
interest (ROI). The method will automatically study the internal
histogram and split it using two pointers. The output BUS image
has improved edge-map and ultimately the segmentation on it is
better compared to regular segmentation using same algorithm
and same initialization. Also, we further processed the edge-map
to have less edge-pixels to area ratio, improving the homogeneity
and the chances of easy segmentation in the future.
Keywords—segmentation, elastography, ultrasound, B-mode,
histogram
I. INTRODUCTION
Breast cancer is the second most deadly cancer for women.
In US only, it was estimated that in 2018-2019, every 1 of 8
US women will develop invasive breast cancer, over 268,600
new cases [1]. The statistics of the previous year 2017-2018,
the number of death was 40,610 [2]. This makes breast
cancer study for ultrasound imaging a pressing need for the
researches. Irteza et. al. [3], [4] described getting strain images
from breast RF data, which can be noisy due to motion of
the patient. Getting segmentation maps along with the strain
images will help the radiologist to diagnose the tumor.
Segmentation is a challenge when applied on ultrasound
images. [5] surveys and describes about segmentation al-
gorithms used on Breast Ultrasound images. [6] mentioned
methods to find out seed point in breast ultrasound images.
[7], [8] mentions that due to poor quality images and noise,
speckle and artifacts, it is relatively harder to find. Many
characteristics dependent segmentation algorithms like the
automatic [9] or semi-automatic [10] or neural networks
such as described in [ref6] have tried to segment the Region
of interest (ROI). Still very high accuracy is not achieved
because the properties of breast tissues [11] plays a big
role in making shadows and low-resolution imaging make it
harder for the algorithm to understand the image. As a first
step towards segmentation, most algorithms take the edge-map
of the image to get an approximate idea about the gradient
change. For ultrasound breast image, the edge image provides
almost no clear information at all. This is due to the fact that
our modern edge determining algorithms find edges that are
very sensitive in nature. Even with slightest of sharp gradient
change, these algorithms such as Canny edge detector [12],
improved Sobel edge detector [13] can find edges. In an
ultrasound image this sensitive property of the edge finding
algorithm works as a double edged sword. It figures out the
ROI but due to unwanted noise, which is many times more
in ultrasound image than in regular image, the edge finding
algorithms also considers the noise and artifacts to be edges.
Regular edge finding algorithms fail to distinguish between
ROI and other artifacts because of low signal to noise ratio
of ultrasound images. Improving the edge image around the
lesion area i.e. clearing out unnecessary noise edges, should
help us do better segmentation with traditional algorithms, at
least theoretically. In this paper, we propose a semi-automatic
technique, that improves the edge-map around the lesion area
of a BUS image, improving the segmentation precision with
regular algorithms.
Improving the edge images require manually initializing two
points on the original image, which will cover a major region
of the ROI and from there the method will initialize a simple
shape automatically. This shape is used to determine estimated
pixel information of the ROI and then two separating pointers
are used on its histogram to filter the main image. This filtered
image, which we call histogram split and stretched image
(HSSI) has a better edge-map with respect to the original edge-
map. General segmentation algorithms such as active contour
[14], level set [15] and MetaMorph [16] segmentation
has yielded better results on these intermediate images. To
measure the improvement, we needed the ground truth of the
original BUS images, which were manually segmented by
978-1-6654-9106–8/22/$31.00 © 2022 IEEE
arXiv:2210.10975v1 [eess.IV] 20 Oct 2022