Prostate Volume Measurement Using Transabdominal ...

Advances in Environment, Biotechnology and Biomedicine

Prostate Volume Measurement Using Transabdominal Ultrasound Scanning

NG KENT HOO, MUHAMMAD AKMAL AYOB, MAHEZA IRNA MOHAMAD SALIM, HEAMN NOORI ABDULJABBAR, EKO SUPRIYANTO Faculty of Health Science and Biomedical Engineering Universiti Teknologi Malaysia 81310, Skudai Malaysia

anges_2405@, ak_battosai@, maheza@biomedical.utm.my, heamn_jabbari@, eko.supriyanto@

Abstract: Prostate volume measurement is frequently used to diagnose the abnormalities of

the prostate. Abnormal enlargement of the prostate may be due to inflammation or virus

infection. In a more severe case, the abnormal enlargement may indicate prostate cancer. The

measurement of the prostatic gland is commonly performed by using transrectal scanning.

However, this scanning method causes uncomfortable feeling. Therefore, this study proposes

the use of transabdominal scanning in the measurement of prostatic volume. The subjects are

requested to fully fill their urinary bladder to obtain clear prostatic gland images. The

measurement is done by computing the ellipsoid formula which calculates the size by

multiplying the largest anteroposterior height (H), transverse width (W), cephalocaudal length

(L) and diameters by

. The quality of the images is then enhanced by using a

series of image processing. The findings show that the prostate size is affected by body size, which means weight and height.

Key-words: - Prostate size, ellipsoid formula, anteroposterior height, transverse width, cephalocaudal length, diameter, body size.

1 Introduction

Prostate is a compound tubuloalveolar

exocrine gland of the male reproductive

system. The function of prostate is to secrete

slightly acidic fluid, which has the

characteristic of milky or white in

appearance. The secretion usually constitutes

20% to 30% of the volume of the semen

along with spermatozoa and seminal vesicle

fluid. In medical practice, most of the

prostate abnormalities are diagnosed by

measuring their volume [2]. Normally, the

prostate volume range has the size of

250

at birth to 100000

sized at

puberty. After puberty, the prostate volume

will continuously grow as the age increase for most of the male's life. The American Cancer society found that prostate cancer is one of the most common cancers affecting the older men in developed countries [3]. It is getting a serious attention from the world as it has become a significant cause of death for elderly men.

2 Problem Background

Since prostate cancer highly leads to death in elderly men population, it is very important to have a good diagnostic method to measure

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the prostate volume. Magnetic resonance imaging (MRI) with an endorectal coil and prostate-specific antigen (PSA) are the most frequently used modality in the prostate volume measurement [4]. Unfortunately, MRI scanning is very time consuming. Therefore, ultrasound has been proven to be the safest and fastest imaging modality. There are several available approaches in ultrasound scanning like transabdominal, transperineal and transrectal scan routes [5]. This study proposes the transabdominal scanning for measuring prostatic volume.

Fig. 1. Prostatic gland [1]

Previous researches on the prostate volume only focused on the subjects' ages [6]. However, that is not the only factor that affects the volume of prostate, as parameters like body weight and height contribute a lot in the differences of prostate size.

3 Literature Review

3.1 Prostate Anatomy

A healthy human male prostate has the volume of 100000 . The prostate is located above the base of the penic and below the urinary bladder and backs into the front wall of rectum. The prostate evolves in this tight-wedged position to aid reproduction. The prostate secretes some of the fluid for semen, stops urination during ejaculation, and enhances sexual pleasureable sensations [7]. Figure 1 shows the anatomy of prostate.

3.2 Size and Measurement

3.2.1 Transrectal Ultrasound

Transrectal ultrasound is a short test that uses ultrasound waves to create an image of the prostatic gland. The test is performed by placing a small and lubricated probe into the rectum. The probe transmits ultrasound waves which create echoes as they enter. The processing unit will receive the echoes that are bounced back and the pattern of echoes will be translated into an image of the prostatic gland [10].

Since mid-1950s, the transrectal route has been introduced for fingerguided prostate biopsy (PBx)[9]. Transrectal route has become the gold standard after Hodge demonstrated higher detection rates for the sextant transrectal ultrasound-guided PBx than sextant finger-guided analog sampling [10].

The transrectal method provides a clear image of organs in the pelvis. Normally, transrectal ultrasound is used for the evaluation of the prostate gland with elevated prostate specific antigen (PSA) or prostatic nodules on digital rectal exam [10].

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3.2.2 Transabdominal Ultrasound

Transabdominal ultrasound is a type of medical ultrasonography used to visualise the structures of abdominal anatomy. The transmitted and reflected ultrasound waves visualize the organs through the abdominal wall. The advantages of transabdominal ultrasound are the procedure can be performed quickly, bed-side, not radiated and non invasive [11].

width (W), cephalocaudal length (L) and

diameters by

[11].

L

W H

4 Methodology

Fig. 2. Prostate size measurement's parameters.

4.1 Subjects

4.4 Image Processing

In this study, 10 subjects from age of 20 years old to 25 years old were selected to undergo the transabdominal scanning. The subjects were randomly selected with different heights and weights. The subjects were the students whom do not have any bad habits like smoking and drinking.

4.2 Prostate scanning

Toshiba Aplio MX was used in the research for prostate scanning. The device was set to a 2D mode and 8 MHz convex transducer was used as the probe. The subjects were instructed to fill their urinary bladder by consuming water. This was done to make sure the prostate could be well-seen under full urinary bladder condition. If the urinary bladder was not fully filled or empty, the prostate images obtained in the scanning would not have a good shape.

The image processing stage was conducted using MATLAB. Further processing is required since the obtained images from the scanning would contain not only prostate, but also urinary bladder and noises. Therefore, noise elimination and segmentation of prostate are important to obtain the desired images. The coding of the overall procedures is shown in the Appendix. By taking an example of the image obtained from the scanning, the segmentation could be done in the few steps.

4.3 Prostate size measurement

Transabdominal scanning method is used in this research. The ellipsoid formula was used to calculate the size by multiplying the largest anteroposterior height (H), transverse

Fig. 3. The procedure of image segmentation.

By using the cropping tool in MATLAB, the desired region was cropped, which was the prostate's region. The image obtained from

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the scanning was not clear and contained a lot of noises. Therefore, a filter tool was needed to de-noise the image. The filter chosen in the study was median filter, which was used to smoothen the image and reduce the noises. The next step was to convert the image from "rgb" format into "bw" format. This process is very important for the edge detection step. However, the detected edges contained unwanted information too, that came from urinary bladder. To eliminate these edges, we used "bwareaopen" to eliminate the areas which were less than 50 pixels. Finally, the image was morphed with the original image.

The purpose of using the segmentation tool for the images is because the comparison of the shapes of prostate is needed for the study. Therefore, segmentation was needed to isolate prostate from the urinary bladder, so that the comparison of the images could be done in an easy way.

5 Results and Analysis

79 31.8 75 32.2 74 29.4 55 28.9

29.4 23.4 29.9 20.0 27.7 23.2 27.3 19.4

7 11454 .8 10082 .2 9892. 6 8014. 2

Table 2. Parameter of measurement and

comparison.

Sujbect Weight Height Prostate

(kg)

(m)

Size

(

1

70

1.68

9563.5

2

77

1.76

10864.6

3

57

1.63

8456.6

4

82

1.80

11686.7

5

62

1.64

8941.4

6

68

1.64

9781.7

7

79

1.78

11454.8

8

75

1.74

10082.2

9

74

1.74

9892.6

10

55

1.62

8014.2

There are 10 subjects who participated in this The data collected were then plotted into a project from the age of 23. The prostate size graph to observe the relationship of the measurements are shown in the table below. prostate size with the body weight.

Table 1. Prostate size measurement of 10

subjects with diffent body weight.

Subj Anteropo Trans Cephal Prosta

ects sterior verse ocaudal te

Wei height width length size

ght (H) (mm) (W) (L)

(

(kg)

(mm) (mm)

70 30.2 77 31.1 57 29.9

28.8 21.0 27.8 24.0 25.6 21.1

) 9563. 5 10864 .6 8456. 6

82 31.0 62 29.9 68 32.0

30.0 24.0 28.7 19.9 27.8 21.0

11686 .7 8941. 4 9781.

Fig. 4. Graph of prostate volume and body weight.

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The graph shows the relationship between the prostate size and the body weight of a male. Normally, the prostate size would show an increment if the age of a male increases. However, in this research, it was found that the body weight and the body size also affected the prostate size. A man with heavier body weight compared to a lighter one will have a larger prostate size. Body fat of a person will reflect the relationship of human growth and development, with the environment under the influence of a person's genotype. The study shows that even the subjects from the same age will not have the same prostate size.

Subject Weight Height (kg) (m)

1

70

1.68

2

77

1.76

3

57

1.63

4

82

1.80

5

62

1.64

6

68

1.64

7

79

1.78

8

75

1.74

9

74

1.74

10

55

1.62

Body Mass Index (BMI) 24.80 24.86 21.45 25.31 23.05 25.28 24.93 24.77 24.44 20.96

Prostate Volume (

9563.5 10864.6 8456.6 11686.7 8941.4 9781.7 11454.8 10082.2 9892.6 8014.2

In this research, the correlation of weight and height was computed by calculating the body mass index (BMI). In order to obtain the trend of correlation, the graph of BMI and prostate size is plotted in Fig. 6.

Fig. 5. Graph of prostate volume and height.

Fig. 4 shows the relationship between the prostate size and the subjects' height. The graph shows that with the increase of height, the prostate size will also increase. There were some special cases, where there were two subjects with the height of 1.64 m, but the prostate sizes did not show a similar value. The reason of this difference was due to the different weight of the subjects. Therefore, the hypothesis is made due to this figures, the weight of the subject is the main factor that affect the prostate size.

Fig. 6. Graph of prostate volume and BMI.

The graph shows that prostate volume would increase if BMI was greater. Therefore, a hypothetical formula was made from the graph.

6 Discussion

Table 3. Correlation of weight, height and Table 4. Increment of prostate volume based

prostate size.

on the differences of height and weight.

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