Ex vivo discrimination between normal and pathological tissues in human breast surgical biopsies using bioimpedance spectroscopy.

Ex vivo bioimpedance data measured on normal and cancerous female breast tissues are reported. They clearly show that the electrical properties of normal tissues, surrounding tissues, and carcinoma are different. These differences lie in the conductivity, in the characteristic frequency (frequency of the maximum of the imaginary part of the bioimpedance), and also in the shape of the Bode plots. Modeling using an R-S-Zcpe model is reported as well as indexes extracted from the real and imaginary parts of the bioimpedance. Even if a classification of the different types of tissues remains a difficult task and leads to much less precise diagnosis than microscopic examination, the electrical behavior of mammary tissue could be used to develop a noninvasive technique for early breast cancer detection.

A multifrequency serial EIT system.

A multifrequency (1 kHz-1 MHz) serial electrical impedance tomography (EIT) system has been developed. It is based on 16 active electrodes and can be extended up to 32. Each active electrode can be programmed for current driving and for measuring either the injected current or the voltage difference between adjacent electrodes, and includes calibration facilities. Real and imaginary parts of the impedance are obtained by applying a parametric identification method (extended Prony), but other techniques are easily adaptable. Image reconstruction is carried out using the Sheffield filtered back-projection algorithm. Characteristic frequency images are under development and should be of great interest to distinguish between normal and tumorous tissues.

Bioelectrical impedance techniques in medicine. Part I: Bioimpedance measurement. Second section: impedance spectrometry.

Electrical impedance spectrometry is an important application field of bioimpedance measurements. After introducing the electrical properties of biological tissues, this part presents instrumental aspects and applications of electrical impedance spectrometry. The main instrumental constraints encountered in spectrometric electrical impedance measurements are reviewed, focusing on low-frequency applications. Examples of impedance cells and probes are presented and several instrumental setups operating in the frequency and time domain are described. Some examples of applications are presented, including in vitro characterization and modeling of normal tissues, in vitro and in vivo characterization of cancerous tissues, and assessment of tissue perfusion/ischemia levels.

Bone cutting.

Bone cutting has always been a problem for surgeons because bone is a hard living material, and many osteotomes are still very crude tools. Technical improvement of these surgical tools has first been their motorization. Studies of the bone cutting process have indicated better features for conventional tools. Several non-conventional osteotomes, particularly ultrasonic osteotomes are described. Some studies on the possible use of lasers for bone cutting are also reported. Use of a pressurised water jet is also briefly examined. Despite their advantages, non-conventional tools still require improvement if they are to be used by surgeons.

[Anterior displacement of the tibial tuberosity. An experimental biomechanical study of its effects on the femoro-patellar joint]. / L'avancement de la tubérosité tibiale. Etude biomécanique expérimentale de ses effets sur l'articulation fémoro-patellaire.

The anterior displacement of the tibial condyle was proposed as early as 1963 by P. Maquet as a therapeutic solution to treat femoropatellar arthritis. However, the benefits of such a procedure remain controversial. In this work, the effects of a 1. cm anterior displacement of the tibial condyle, with and without section of the patellar wings, have been studied on the knees of fresh corpses without osteoarthritis. The knees were tested in flexion from 10 to 70 degrees. The study dealt with the contact surfaces, pressures, and femoropatellar forces, which were analyzed with an original and efficient measurement system, with the Fuji Prescale Film as a sensor. This study showed that the femoropatellar contact has not been significantly modified by the displacement of the tibial condyle. We have noted only a slight decrease in the pressure after this type of surgery. These results are in contradiction with Marquet's results. In all cases, the anterior displacement of the tibial condyle with resection of both patellar wings produced the best results. These results suggest that displacing the tibial condyle anteriorly does not have the expected effects. The indication of such a surgical procedure must therefore be established only cautiously and after ruling out other therapeutic methods.

Electrets for use as dosimeters in radiography.

A compact device for the manufacturing of electrets and for the measurement of the dose to the skin of the patient in radiography has been developed and described. The surface potential of a polarized polymer electret decreases when it is exposed to radiation. The measurement of the variation in surface potential appears to be a reliable method for the evaluation of the dose. The electret does not disturb the examination nor the radiographic image as it can be given tissue equivalent properties.