The Cole relaxation frequency as a parameter to identify cancer in breast tissue.

PURPOSE: To correlate the Cole relaxation frequencies obtained from measurements of the electrical properties of breast tissue to the presence or absence of cancer. METHODS: Four-lead impedance measurements were obtained on ex vivo specimens extracted during surgery from 187 volunteer patients. Data were acquired with a commercial Solartron impedance bridge employing 4-lead Ag-AgCl or blackened platinum (BPt) electrodes at frequencies logarithmically spaced from 1 Hz to 3.2 × 10(7) Hz utilizing 6-10 frequencies per decade. The Cole frequencies obtained from these measurements were correlated with the tissue health status (cancer or noncancer) obtained from histological analysis of the specimens. RESULTS: Analysis of the impedance measurements showed that the Cole relaxation frequencies correlated to the presence or absence of cancer in the examined tissue with a sensitivity up to 100% (95% CI, 99%-100%) and a specificity up to 85% (95% CI, 79%-91%) based on the ROC curve of the data with the Cole frequency as the classifier. CONCLUSIONS: The results show that the Cole frequency alone is a viable classifier for malignant breast anomalies. Results of the current work are consistent with recent bioimpedance measurements on single cell and cell suspension breast cell lines.

Correction of electrode polarization contributions to the dielectric properties of normal and cancerous breast tissues at audio/radiofrequencies.

Spurious contributions from electrode polarization (EP) are a major nuisance in dielectric measurements of biological tissues and hamper accurate determination of tissue properties in the audio/radiofrequencies. Various electrode geometries and/or treatments have been employed traditionally to reduce EP contributions, although none succeeded to completely remove EP from measurements on tissues for all practical frequency ranges. A method of correction for contributions of EP to the dielectric properties of tissues is proposed. The method is based on modeling the electrode impedance with suitable functions and on the observation that certain parameters are only dependent on electrodes properties and can thus be determined separately. The method is tested on various samples with known properties, and its usefulness is demonstrated with samples of normal and cancerous human female breast tissue. It is observed that the dielectric properties of the tissues over the frequency range 40 Hz-100 MHz are significantly different among different types of breast tissue. This observation is used further to demonstrate that, by scanning the tip of the measuring dielectric probe (with modest spatial resolution) across a sample of excised breast tissue, significant variations in the electrical properties are detected at a position where a tumor is located. This study shows that dielectric spectroscopy has the potential to offer a viable alternative to the current methods for detection of breast cancer in vivo.

Abdominopelvic computerized tomography and open peritoneal lavage in patients with blunt abdominal trauma: a prospective study.

This prospective trial compares abdominopelvic computerized tomography and open peritoneal lavage in the diagnosis of blunt abdominal trauma. Fifteen patients (group 1) were evaluated by both methods. Another 15 patients (group 2) had only computerized tomography. Criteria for a "positive" scan were hemoperitoneum and evidence of solid organ injury. Criteria for "positive" lavage were a grossly bloody return, erythrocyte count greater than 20.0 X 10(9)/L and leukocyte count greater than 0.5 X 10(9)/L. At laparotomy, only injuries requiring repair or excision were considered "true positive". Patients who did not have laparotomy and had an uncomplicated clinical course were considered "true negative". With tomographic criteria alone for diagnosis there would have been one false-positive and three false-negative results, compared with three false positive and no false negatives for open peritoneal lavage alone. None of the three patients who had negative findings on laparotomy suffered any morbidity or died. Results of computerized tomography and open peritoneal lavage agreed in 8 of 15 patients (kappa value = 0.52), indicating a low level of agreement between the two. The authors believe that open peritoneal lavage remains the diagnostic procedure of choice in blunt abdominal trauma.

An outbreak of Staphylococcus epidermidis septicemia.

During 45 wk from August 1980 to June 1981, the catheter sepsis rate increased from a prior 2 to 34% (23 of 68 patients on intravenous hyperalimentation). The causative organism was Staphylococcus epidermidis, grown on blood cultures in 21 of the 23 patients and on the catheter-tips of all 23. Routine cultures of the catheter-tips of the 45 patients who received intravenous hyperalimentation during this period with no evidence of catheter sepsis grew S. epidermidis on three catheter-tips (6.7%), possibly contamination during catheter removal. Sepsis resolved within 24 hr after catheter removal, with no antibiotics given for the sepsis. The organism had identical antibiograms on the blood and catheter-tip cultures in each patient, but antibiograms varied between patients. In these complex patients undergoing multiple medical events, the intravenous hyperalimentation nurse recorded that iv tubing in septic patients had leaked solution at the attachment to the catheter hub, and a review of nursing notes on charts of patients who had been on intravenous hyperalimentation revealed that a leak had been noted in the patients who subsequently had catheter sepsis. The leak was due to a manufacturing defect resulting in a decrease in diameter of the plastic connection of the iv tubing, which produced a loose attachment to the hub. The problem was remedied by switching to a Luer-lok attachment. However, in July 1982, two patients had separation of the Luer due to a manufacturing defect in the threads, followed by a catheter sepsis. Sepsis from the local contamination was not manifest until 5.4 +/- 2.7 days later. Quality control by manufacturers is emphasized.

Evidence of morphological and physiological transformation of mammalian cells by strong magnetic fields.

Cultures of L-929 and WI-38 cells, frozen to 4.2 degrees K and exposed for 4 to 8 hours to 5000-oersted magnetic fields, were markedly inhibited in their growth as compared to controls. In cultures grown on cover slips, approximately 7 days after exposure, morphologically distinct cells emerged and were propagated from generation to generation; 3 weeks later, in flask cultures, contact inhibition was abolished. It is concluded that under certain experimental conditions, strong magnetic fields induce morphological and physiological transformations of target cells.