Q and A

1. What forms the basis for the impedance mammography in diagnostics of breast disease?
A living organism does not only generate bioelectricity, but passively conducts the current, which occurs in it or is applied from outside. Electrical conductivity depends on the histological structure of the organ, its molecular and, finally, its elementary composition (structure and number of free electrical charges, their mobility). Electrical properties of many malignant formations considerably differ from the healthy tissues, surrounding them. If X-ray and ultrasound methods of diagnostics construct images using the level of contrast between healthy and malignant tissue, which amounts to several percent and less, in case of impedance diagnostics the electrical conductivity of such tissues might amount to several hundreds of percent. This phenomenon is used in detection and localization of tumours and other breast disease.

2. What is impedance?
It is a physical value, which characterizes the electrical resistance of the system (from Latin impedire — “to cause hindrance”. Electrical impedance is a total resistance of the electrical circuit to the alternative current passing through it. In general, it is a geometrical sum of active resistance of the electrical circuit and reactive resistance (reactance), measured in Om.

3. What parameters of electrical current can be used in medicine, and in mammology in particular?
In medical diagnostics, particularly in electroimpedance mammography, the alternative current of a rather high frequency is used (as a rule, over 1 kHz). Due to high polarization degree of the intercellular membranes and the working electrodes electrical conductivity, measurements of biological systems, using direct current, is extremely difficult. The permissible value of the current is limited by its biological impact on the cells of living tissue; the former grows with the frequency increase. The current used for scanning in the electroimpedance computer mammography “MEIK”® (5th version) is within the range of 0,5 mA, frequency 50 kHz. These parameters of the measurement systems are absolutely harmless for patients.

4. What are the outlooks for utilizing the multi-frequency scanning?
We studied possibilities of the multi-frequency scanning for visualization of mammary tumor. ("Electro-impedance mammography testing at some physiological woman's periods". A.Karpov, O.Trochanova, XI international conference on electrical bio-impedance. Oslo, Norway, 2001; �Changes in electrical conductivity of mammary gland at multi-frequency measurement�, A.Karpov, O.Trochanova, XVIII scientific and practical conference. Yaroslavl, 2001). But application of the current with frequency within the range of β- dispersion ( 102 � 108 Hz) for breast scanning failed to bring the expected results. The 5th version of �MEIK� comprises this possibility. We recommend using it only as a tool for research only.

5. How painful is the examination?
The examination, being absolutely painless during the diagnostics and after it, lasts about 30 seconds.

6. What are the indications for impedance mammography?
The electrical impedance can be utilized in the whole range of the breast diseases, namely: benign and malignant neoplasms, mastopathies, mastitis and so on. In addition electrical impedance can be used for dynamic monitoring of women, comprising a risk group, in order to check efficiency of treatment. The examination, done with the help of MIEK during pregnancy as well as after birth, supplies doctors with valuable information concerning particulars of lactation period. This method of screening is widely used for women who take oral contraceptives and undergo substitutive hormonotherapy in climacterical stages.

7. Do any contraindications exist for using the method of impedance mammography?
Impedance mammography is absolutely harmless for a human being; this is why it can be used at any age period, inclusive lactation and pregnancy.

8. How often can impedance mammography be used?
The examination can be used without time limitations, since it is not accompanied by any radiation exposure and is safe for patients. The examination can be carried out when recommended by the physician at any time intervals. It can be used during a menstrual cycle in order to define breast functional particulars (so called dynamic mammography). In perimenopause it should be done at least one a year.

9. Who should conduct the examination in question?
The examination, connected with impedance mammography, should be performed by doctors, familiar with breast anatomy, physiology and pathology, namely: mammologists, obstetricians, or specialists in radiodiagnostics. When carrying out the examination it is preferable to have a nurse�s assistance, since it speeds up the procedure and increases efficiency.

10. Is it possible to diagnose breast malignant growth?
Due to the difference in electrical conductivity of malignant and healthy tissues existing from the initial stage of the tumour process, the device is capable of performing early detection of the oncology pathologies.

11. What minimal size of a tumour can be detected with the help of impedance mammography?
According to the existing statistic data the smallest detected tumours were 3-5 mm.

12. What are the operational characteristics of impedance mammography (sensitivity, specificity, etc)?
Sensitivity amounts to.92%, specificity-.99%, prognostication of positive - 73%, prognostication of negative result - 99%.

13. What method should be used for detection of malignant diseases? — for benign diseases?
It is not correct to discuss preferences any method in detecting any disease. There are no 100% results in diagnostics either in case of benign or malignant diseases of breast anywhere in the world. When choosing the appropriate method one should be guided by the criteria of safety and appropriateness. Taking into account high degree of sensitivity and specificity of the impedance mammography and at the same time its absolute safety, we can recommend starting examination with this method in particular. It case of necessity a more detailed examination can be recommended.

14. Is it recommendable to use the method in question for screening purposes?
The method of impedance mammography meets all demands of screening: safety, affordability, comprehensiveness; it can be performed within a short period of time in a room with limited sizes.

15. Does impedance mammography examination require any special condition?
The impedance mammography doesn�t need any special procedures. The examination is carried out at a room temperature, in rooms with average humidity. The patient takes a lying position on the examination couch.

16. How long does the examination last?
The length of examination procedure is 30 - 35 seconds. The process of diagnostic examination from the moment of obtaining the case history to establishing a conclusion amounts to 15 minutes. Screening examination lasts about 5 minutes.

17. What is the cost of the examination procedure?
When comparing the cost of various equipment, utilized for the same purposes, it is possible to say that the examination in question is cheaper than X-ray mammography and ultrasound examination.

18. Can the impedance mammography provoke any complications?
We have never witnessed any complications after impedance mammography.


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