**3. Technical requirements and safety assurances for doctors and patients**


## **4. Examination quality criteria**

For high-quality diagnostic and continuity of work it is necessary that electrical impedance mammograms met specific quality criteria.


macromolecules. Moreover, the polarization ability of the cell membrane itself due to protein and lipid structures determines its exceptional electrical properties. Thus, the electrical properties of biological tissue as a colloid-disperse system in an alternating electric field are determined by the concentration and «the behaviour» of chemical


compounds in it.

**2. Indications for application** 


intensity - 0.5 mA.



not induce pain or other sensations.


mammograms met specific quality criteria.


the image.

gland).

**4. Examination quality criteria** 

breast shall be avoided.

adjustments shall be displayed on the screen.



using the percentile curves of the age-related electrical conductivity.


**3. Technical requirements and safety assurances for doctors and patients** 




For high-quality diagnostic and continuity of work it is necessary that electrical impedance





physiological period, other features, for example, skin changes.



## **5. Types of mammary gland structure from the perspective of electrical impedance mammography**

Electrical conductivity index (IC), calculated during the electrical impedance examination, is a quantitative value, which characterizes the status of the breast. The results of 1,632 electrical impedance mammograph examinations, obtained from healthy women from different age groups, were analyzed. The women were selected for the examination according to the following criteria: absence of complaints on the mammary glands, a normal menstrual cycle, uncomplicated perimenopausal period, absence of chronic somatic and gynaecological diseases and absence of hormonal contraceptives taking or hormone replacement therapy. The women were distributed by age in years as follows: 20-30 (380 women), 31-40 (428), 41-50 (449) and 51-60 (375). All the examinations described in the chapter were carried out with the help of the electroimpedance computer mammograph "MEIK" v.5.6 (0.5 mА, 50 kHz), developed and manufactured by PKF "SIM-Technika", Russia.

Fluctuations of electrical conductivity index in 1,632 studies were as follows: lower limit – 0.01 conventional units, upper limit – 0.68 conventional units. In order to identify the structure of electrical impedance index distribution there were elaborated 8 ranges of criteria at a step of 0.09 and the quantity of studies was calculated in each range (Table 1).


Table 1. Arrangement of electrical conductivity index frequencies.

Fig. 1 shows the frequency histogram of electrical conductivity index data. Mean electrical conductivity index constituted 0.29, median value – 0.29 and mode - 0.26.

Taking into consideration a bell-shaped curve, close mean, median and mode values one can speak about standard (Gauss) distribution of the quantitative value, in this case, of electrical conductivity index. Typically, mean value and standard deviation are used to describe standard distribution. More detailed data can be obtained using 3th, 10th, 25th, 40th, 75th, 90th and 97th percentiles (Figure 2). In this case, the information on the shape of criterion distribution graph is not required.

Standards for Electrical Impedance Mammography 163

The low electrical conductivity index of the mammary glands typical for women aged from 20 to 30 are conditioned by the peculiarities of breast's anatomy. This group of women is characterized by the prevalence of ductal and acinar epithelium over connective tissue in the mammary gland structure. The phenomenon of low conductivity can be explained by the presence of a large number of membranes of epithelium cells in the mamma. It is known that cell membranes possess capacitance and act as a strong barrier for electrical current. Therefore, a large amount of lactiferous ducts and lobules in the mamma (implying the presence of a large number of cell membranes) conditions low electrical conductivity. The predominance of women in this age group is observed in two percentile ranges - less than 3rd percentile and from 3rd to 10th percentile. Therefore, the status of mammary glands possessing electrical conductivity index lower than 0.14 cu, should be regarded as ductal

Fig. 4. EIM. Seven scan planes. A 21 years-old patient. Acinar/ductal type of mammary gland structure. Low values of electrical conductivity index (less than 10 pct). On the right -

Fig. 3. Age-related characteristics of percentile ranges.

and acinar type of the breast structure (Fig. 4).

ultrasound image.

Fig. 1. Frequency histogram of electrical conductivity index data.

Fig. 2. Frequency histogram of electrical conductivity index data and percentile ranges.

The following pattern was identified after the age-related characteristics of women belonging to the percentile ranges were analyzed. Women aged from 20 to 30, whose data fell to the ranges less than 3rd percentile (IC<0.09) and from 3rd to 10th percentile (IC=0.1- 1.4) constituted more than 50%. Women aged from 50 to 60, whose data fell to the ranges higher than 97th percentile (IC>0.53) and from 90th to 97th percentile (IC=0.47-0.52) constituted more than 50%. Age of the women whose data ranged between 25th and 75th percentiles (IC=0.21-0.39) distributed in a uniform manner, the percentage of each agegroup constituted from 20 to 30% without any prevalence (Figure 3).

Fig. 1. Frequency histogram of electrical conductivity index data.

Fig. 2. Frequency histogram of electrical conductivity index data and percentile ranges.

group constituted from 20 to 30% without any prevalence (Figure 3).

The following pattern was identified after the age-related characteristics of women belonging to the percentile ranges were analyzed. Women aged from 20 to 30, whose data fell to the ranges less than 3rd percentile (IC<0.09) and from 3rd to 10th percentile (IC=0.1- 1.4) constituted more than 50%. Women aged from 50 to 60, whose data fell to the ranges higher than 97th percentile (IC>0.53) and from 90th to 97th percentile (IC=0.47-0.52) constituted more than 50%. Age of the women whose data ranged between 25th and 75th percentiles (IC=0.21-0.39) distributed in a uniform manner, the percentage of each age-

Fig. 3. Age-related characteristics of percentile ranges.

The low electrical conductivity index of the mammary glands typical for women aged from 20 to 30 are conditioned by the peculiarities of breast's anatomy. This group of women is characterized by the prevalence of ductal and acinar epithelium over connective tissue in the mammary gland structure. The phenomenon of low conductivity can be explained by the presence of a large number of membranes of epithelium cells in the mamma. It is known that cell membranes possess capacitance and act as a strong barrier for electrical current. Therefore, a large amount of lactiferous ducts and lobules in the mamma (implying the presence of a large number of cell membranes) conditions low electrical conductivity. The predominance of women in this age group is observed in two percentile ranges - less than 3rd percentile and from 3rd to 10th percentile. Therefore, the status of mammary glands possessing electrical conductivity index lower than 0.14 cu, should be regarded as ductal and acinar type of the breast structure (Fig. 4).

Fig. 4. EIM. Seven scan planes. A 21 years-old patient. Acinar/ductal type of mammary gland structure. Low values of electrical conductivity index (less than 10 pct). On the right ultrasound image.

Standards for Electrical Impedance Mammography 165

Within the ranges from 10th to 25th percentile and from 75 to 90th percentile the data of two age groups of women prevail. Therefore, the status of mammary glands possessing electrical conductivity index within these ranges, should be regarded as a mixed type of the mammary gland structure with prevalence of acinar/ductal or amorphous component

Below the summary table of structure estimates for the breast in terms of electrical

structure. above 0.47 >90‰

with amorphous component predominance. 0,40 – 0,46 75-90‰

Type II Mixed type of mammary gland structure. 0,21 – 0,39 25-75‰

Table 2. Types of mammary gland structure from the perspective of electrical impedance

Thus the estimation of mammary gland structure from the perspective of electrical impedance mammography using electrical conductivity index is possible. It is known that the structure of the mammary gland determines their density. Thus, the defined ranges of electric conductivity correspond to different types of mammary gland "density". Low values of electric conductivity correspond to "dense" breasts of the so-called combined ductal/lobular type. High values of electrical conductivity index are characteristics of the amorphous type of breasts, consisting mainly of fat and connective tissue. A distinctive feature of this method for evaluating structure of the breast is the expression of its anatomical and histological structure in numerical terms. Estimation of the density of mammary glands from the perspective of electrical impedance mammography using

conductivity Percentiles

0,14 – 0,20 10-25‰

below 0.14 <10‰

Formulation Electrical

Amorphous type of mammary gland

Mixed type of mammary gland structure

Mixed type of mammary gland structure

Acinar/ductal type of mammary gland

Extremely high density of acinar/ductal

electrical conductivity index in *ACR* terms is provided below (Table 3).

with acinar/ductal component predominance. High density of ductal

component.

structure.

component

respectively.

Type Iа

Type Ib

Type III

Type IV

mammography.

impedance mammography is provided (Table 2).

"Loss" of acinar/ductal epithelium in women aged from 50 to 60 is the reason for high electrical conductivity index of the mammary glands. When progressive decrease of estradiol secretion occurs, terminal-duct secretory epithelium is substituted by connective tissue with a varied correlation of tissue elements. Intercellular substance includes the ground substance, which contains a large amount of mucopolysaccharides. Loose connective tissue, filling the space between bodies, blood vessels, nerves, muscles and other structures of the body, creates the internal environment, through which the delivery of nutrients to cells and the removal of the waste products of their metabolism are carried out. The major mucopolysaccharide of the ground substance of connective tissue is hyaluronic acid, which carries a large number of negative charges. Its ability to bind and retain water dipoles determines the electrical properties of amorphous substance of connective tissue, making it a good conductor. Therefore, the predominance of connective tissue in the breast should expect high electrical conductivity. The predominance of women in this age group is observed in two percentile ranges - more than 97th percentile and from 90th to 97th percentile. Therefore, the status of mammary glands possessing electrical conductivity index higher than 0.47 cu, should be regarded as amorphous type of the mammary gland structure (Fig. 5).

Fig. 5. EIM. Seven scan planes. A 52 years-old patient. Amorphous type of mammary gland structure. High values of mean electrical conductivity index – (> 90 pct). On the right - X-ray mammogram.

Different combinations of acinar/ductal components and connective tissue with adipocytes are the reasons for electrical conductivity index variations from 0.21-0.39 in women of all age groups. Therefore, the status of mammary glands possessing electrical conductivity index within the range from 0.21 to 0.39 cu, should be regarded as a mixed type of the mammary gland structure. Different combinations of the structures that determine the conductivity of tissues, define the wide range of the values of electrical conductivity index (Fig. 6).

Fig. 6. EIM. Seven scan planes. Age 39 years. Mixed type of mammary gland structure. Mean electrical conductivity index – 25-75 pct. On the right - X-ray mammogram.

"Loss" of acinar/ductal epithelium in women aged from 50 to 60 is the reason for high electrical conductivity index of the mammary glands. When progressive decrease of estradiol secretion occurs, terminal-duct secretory epithelium is substituted by connective tissue with a varied correlation of tissue elements. Intercellular substance includes the ground substance, which contains a large amount of mucopolysaccharides. Loose connective tissue, filling the space between bodies, blood vessels, nerves, muscles and other structures of the body, creates the internal environment, through which the delivery of nutrients to cells and the removal of the waste products of their metabolism are carried out. The major mucopolysaccharide of the ground substance of connective tissue is hyaluronic acid, which carries a large number of negative charges. Its ability to bind and retain water dipoles determines the electrical properties of amorphous substance of connective tissue, making it a good conductor. Therefore, the predominance of connective tissue in the breast should expect high electrical conductivity. The predominance of women in this age group is observed in two percentile ranges - more than 97th percentile and from 90th to 97th percentile. Therefore, the status of mammary glands possessing electrical conductivity index higher than 0.47 cu, should be

Fig. 5. EIM. Seven scan planes. A 52 years-old patient. Amorphous type of mammary gland structure. High values of mean electrical conductivity index – (> 90 pct). On the right - X-ray

Different combinations of acinar/ductal components and connective tissue with adipocytes are the reasons for electrical conductivity index variations from 0.21-0.39 in women of all age groups. Therefore, the status of mammary glands possessing electrical conductivity index within the range from 0.21 to 0.39 cu, should be regarded as a mixed type of the mammary gland structure. Different combinations of the structures that determine the conductivity of

tissues, define the wide range of the values of electrical conductivity index (Fig. 6).

Fig. 6. EIM. Seven scan planes. Age 39 years. Mixed type of mammary gland structure. Mean electrical conductivity index – 25-75 pct. On the right - X-ray mammogram.

regarded as amorphous type of the mammary gland structure (Fig. 5).

mammogram.

Within the ranges from 10th to 25th percentile and from 75 to 90th percentile the data of two age groups of women prevail. Therefore, the status of mammary glands possessing electrical conductivity index within these ranges, should be regarded as a mixed type of the mammary gland structure with prevalence of acinar/ductal or amorphous component respectively.

Below the summary table of structure estimates for the breast in terms of electrical impedance mammography is provided (Table 2).


Table 2. Types of mammary gland structure from the perspective of electrical impedance mammography.

Thus the estimation of mammary gland structure from the perspective of electrical impedance mammography using electrical conductivity index is possible. It is known that the structure of the mammary gland determines their density. Thus, the defined ranges of electric conductivity correspond to different types of mammary gland "density". Low values of electric conductivity correspond to "dense" breasts of the so-called combined ductal/lobular type. High values of electrical conductivity index are characteristics of the amorphous type of breasts, consisting mainly of fat and connective tissue. A distinctive feature of this method for evaluating structure of the breast is the expression of its anatomical and histological structure in numerical terms. Estimation of the density of mammary glands from the perspective of electrical impedance mammography using electrical conductivity index in *ACR* terms is provided below (Table 3).

Standards for Electrical Impedance Mammography 167

Fig. 7. EIM. Seven scan planes. Connective tissue septa, radiating from the areola (indicated

One distinguishes the parenchyma, which consists of alveolar-tubular glands, and the connective tissue stroma, which is represented by a small amount of cells, delicate fibres and ground intercellular substance. The parenchyma is characterized by an isoimpedance

Fig. 8. EIM. Seven scan planes. Parenchyma as isoimpedance areas located between the

Before reaching the nipple milk ducts gain in breadth and create a lactiferous sinus (sinus lactiferi) which accumulates secreta as well as the milk. There are about 15-25 sini in the retromammilary area. The lactiferous sinus zone is visualized as a vast hypoimpedance area

Fig. 9. EIM. Seven scan planes. A hypoimpedance area in the centre of the mammogram corresponds to the location of the lactiferous sinus zone (indicated with arrows).

The nipple consists of the excretory ducts of the breast lobes, surrounded by fibrous tissue and a large number of sebaceous glands. High electrical impedance of the nipple is determined by the absence of the excretory ducts of perspiratory glands in it. In the electrical impedance tomogram the nipple is visualized in the centre as a circular or linear

hyperimpedance area, located closely to the lactiferous sinus zone (fig. 10).

with arrows).

**6.2.2 The parenchyma** 

structure and is located between the septa. (Fig. 8).

connective tissue septa (indicated with arrows).

located in the centre of the mammogram (fig. 9).

**6.2.3 The lactiferous sinus zone** 

**6.2.4 The nipple** 


Table 3. Mammary gland structure from the perspective of electrical impedance mammography execution and breast density types according to the classification of the American College of Radiology (ACR).
