The impact of lesion vascularisation on tumours detection by electrical impedance scanning at 200 Hz.

OBJECTIVE: Cancer cells exhibit altered local dielectric properties compared to normal cells. These properties are measurable as a difference in electrical conductance using electrical impedance scanning (EIS). EIS is at present not sufficiently accurate for clinical routine despite its technological advantages. To modify the technology and increase its accuracy, the factors that influence precision need to be analysed and identified. While size, depth, localisation and invasiveness affect sensitivity, vascularisation might show an increased conductance and thus might affect specificity. SUBJECTS AND METHODS: All patients were investigated with EIS (TransScan TS 2000, Migdal Ha Emek, Israel) Planned DCE-MRI prior to histological clarification were included (295 lesions). Dynamic enhancements were assigned scores after analysis of subtracted images after application of Gd-DTPA. D1: strong enhancement of >100% from initial signal obtained on native T1weighted sequence; D2: moderate enhancement 50-100%; D3: enhancement similar to glandular tissue, <50%; D4: subtle or no enhancement, less then surrounding glandular tissue. RESULTS: 89/113 malignant and 107/182 benign findings were visible by a focal increased conductance and/or capacitance using EIS (Sensitivity 79%, Specificity 59%). DCE-MRI was aborted due to claustrophobia in 17/295 cases. MR was used and out of 278 completed MR examinations, 101/104 malignant and 141/174 benign lesions were correctly diagnosed as benign or malignant leading to a sensitivity of 97% and a specificity of 81%. D1 benign lesions were positive in EIS in 33/55 cases suggesting a specificity of 44.4%. This value increases significantly with decreased vascularity to 68.9% (D2-4; 82/119). Out of 60 fibroadenomatous lesions, 10/23 fibroadenomas in class 1 had no focal increased conductance or capacitance and were thus considered as non-suspicious in EIS. The same result was applicable for the 29/37 benign lesions with a D2-4 contrast uptake (43.5% vs. 78.4%, p<.01). CONCLUSION: Vascularisation influences the measurable conductance at low frequency and therefore partially causes the insufficiently low specificity of EIS. Impedance measurements at frequencies in a range of 0.1 KHz to 1 MHz are required . According to theoretical and in vitro studies this might increase the accuracy of EIS technology. © 2007 Biomedical Imaging and Intervention Journal. All rights reserved.

[Evaluation of the primary diagnosis with a CAD-system in mammography]. / Evaluation der Primärbefundung durch ein CAD-System in der Mammadiagnostik.

PURPOSE: To assess the capability of the computer assisted detection (CAD) system to classify calcifications that are histologically verified as malignant and benign or are proven benign by magnification and follow up mammography. MATERIALS AND METHODS: Three groups of microcalcifications (MC) with and without associated masses were enrolled in the study. The cancer group included 141 screen-detected breast cancer cases. One benign group comprised 109 cases with histologically benign specimens obtained through a minimally invasive breast biopsy. A second benign group included 72 lesions with MC that appeared benign on magnification/compression views and were confirmed to be benign on follow-up mammograms over a period of at least 1.5 years. All mammograms were evaluated with a CAD system (Second Look version 3.5, CADx Medical Systems, Canada). RESULTS: CAD correctly detected 125 of 141 (89 %) cancer cases. Of the 16 false negative cases, CAD marked the location of the MC (which were associated with malignant mass) with a mass mark in 12 cases. For benign cases, CAD did not correctly mark the microcalcifications in 59 of the 109 lesions confirmed benign histologically (54.1 %) and in 39 of the 72 lesions established benign mammographically (54.2 %). Adenosis introduced the highest rate of falsely marked microcalcifications (62 %). CONCLUSION: Due to its limited specificity, CAD can still not be recommended for the primary classification of microcalcifications as malignant or benign. Nevertheless, the low false negative rate and rather high detection rate of malignant findings indicate some value of CAD for an independent second reading.

Electrical impedance scanning used in addition to ultrasound for the verification of submandibular and parotid lesions: initial results.

OBJECTIVES: Different dielectric properties of cancerous tissues are correlated with increased conductance potentially measurable using Electrical Impedance Scanning (EIS). Sonographically based differentiation of lesions in the salivary glands remains difficult. The clinical value of EIS used additionally to Ultrasound was investigated. METHODS: Sonographically suspicious lesions of parotid (n = 25) and submandibular (n = 16) glands were examined using TransScan TS2000 (TransScan Medical, Israel; distributed by Siemens, Sweden). Bright focal spots representing areas of high conductance were read as positive; absence of a focal spot (ie, homogeneous gray) was read as negative. All lesions were histopathologically proved. RESULTS: 14/15 malignant (93.3%) and 13/26 benign lesions (50.0%) were correctly detected using EIS, NPV 93%, PPV 52%. All cases of squamous cell carcinoma were correctly identified. Lymph node relapse of T-cell lymphoma, lymph node relapse of malignant melanoma, malignant hemangioendothelioma and 2/3 adenocystic carcinoma (primary metastases) were correctly detected. CONCLUSIONS: Our initial results suggest EIS to be of interest when used adjunctively to ultrasound for the identification of malignant lesions of the salivary glands. However, low specificity induced in part by current technical restrictions (bone interference, skin alterations, contact artifacts, prominence of the lesions) limit this clinical application.

Electrical impedance scanning of lymph nodes: initial clinical and technical findings.

PURPOSE: The sonographic differentiation between inflammatory and malignant lymph node enlargement remains imprecise. Electrical impedance scanning (EIS) is of more value in malignant breast lesions, and this study was undertaken to determine if it was of use in differentiating nodal enlargement. MATERIALS AND METHODS: Two hundred and thirty-six sonographically suspicious lymph nodes (146 patients) of mean size 18 x 11 x 11 mm mean depth 9 mm were examined using a commercially available electrical impedance imaging system. The following locations of lymph nodes were included in the study: cervical, axillary, inguinal, supraclavicular and chest/abdominal wall. The EIS results were compared to histopathological, serological or follow up findings. RESULTS: Using EIS 105/115 malignant nodes were correctly diagnosed, while 70/121 inflammatory or benign lymph nodes were correctly identified as benign by EIS (10 false-negative, 51 false-positive). Sensitivity (91.3%) and specificity (57.9%) were obtained. Corresponding negative and positive predictive values were 87.5% and 67.3%, respectively. CONCLUSIONS: Results from this initial study suggest potential value for EIS as an imaging adjunct in the differentiation of sonographically equivocal lesions. Best accuracy was achieved at chest/abdominal wall and inguinal locations. Due to technical restrictions with the present system, the examination of inframandibular and para-aortal lymph nodes should be limited to special cases.

Use of electrical impedance scanning in the differentiation of sonographically suspicious and highly suspicious lymph nodes of the head-neck region.

Sonographic differentiation between inflammatory and malignant lymph nodes is difficult, due in part to almost unchanged morphology of small lymph node metastases; however, as cancer cells exhibit altered dielectric properties, measurement of local electrical field distortions may be useful as adjunct to ultrasound in detection of malignancy. In this study, we evaluated the ability of electrical impedance scanning (EIS) to differentiate cervically located sonographically suspicious or highly suspicious lymph nodes. Seventy patients with 106 sonographically suspicious lymph nodes (mean size 20 x 13 x 13 mm, mean depth 8 mm) were examined using TransScan TS2000 (Siemens, Erlangen, Germany; manufactured by TransScan Research and Development Co., Israel). Included in the study were cervical ( n=64), inframandibular/periparotideal ( n=32) and nuchal/supraclavicular ( n=10) nodes. The EIS results were compared with histopathological ( n=100) and serological ( n=6) findings. Sixty-two of 64 malignant lymph nodes were correctly detected using EIS; 19 of 42 inflammatory/benign lymph nodes were correctly identified as benign (true positive 96.9%, true negative 45.2%; accuracy 71.3%, negative predictive value 90.5%, positive predictive value 59.6%). The high tumour detection rate achieved in this study suggests that EIS may be of value as an adjunctive technique in differentiation of lymph nodes of the head-neck region. Software changes to reduce the high number of false-positive markers are, however, necessary to improve the value in the evaluation during a regular clinical routine.

Tumour detection rate of a new commercially available computer-aided detection system.

The aim of this study was to determine the tumour detection rate and false positive rate of a new mammographic computer-aided detection system (CAD) in order to assess its clinical usefulness. The craniocaudal and oblique images of 150 suspicious mammograms from 150 patients that were histologically proven to be malignant were analysed using the Second Look CAD (CADx Medical Systems, Quebec, Canada). Cases were selected randomly using the clinic's internal tumour case sampler. Correct marking of the malignant lesion in at least one view was scored as a true positive. Marks not at the location of the malignant lesion were scored as false positives. In addition, mammograms with histologically proven benign masses ( n=50) and microcalcifications ( n=50), as well as 100 non-suspicious mammograms, were scanned in order to determine the value of false-positive marks per image. The 150 mammograms included 94 lesions that were suspicious due to masses, 26 due to microcalcifications and 30 showed both signs of malignancy. The overall sensitivity was 90.0% (135 of 150). Sensitivity on subsets of the data was 88.7% (110 of 124) for suspicious masses (MA) and 98.2% (55 of 56) for microcalcifications. Eight of 14 false-negative cases were large lesions. The overall false-positive rate was observed as 0.28 and 0.97 marks per image of microcalcifications and masses, respectively. The lowest false-positive rates for microcalcifications and MA were observed in the cancer subgroup, whereas the highest false-positive rates were scored in the benign but mammographically suspicious subgroups, respectively. The new CAD system shows a high tumour detection rate, with approximately 1.3 false positive marks per image. These results suggest that this system might be clinically useful as a second reader of mammograms. The system performance was particularly useful for detecting microcalcifications.

Additional value of electrical impedance scanning: experience of 240 histologically-proven breast lesions.

The aim of this study was to quantify the clinical value of using electrical impedance scanning (EIS) as an adjunct to other diagnostic techniques in order to identify cancerous tissue based upon its inherent altered local dielectric properties. 210 consecutive women with 240 sonographically and/or mammographically suspicious findings were examined using EIS. All lesions were histologically-proven. 86/103 malignant and 91/137 benign lesions were correctly identified using EIS (87.8% sensitivity, 66.4% specificity). NPV and PPV of 84.3% and 65.2% were observed, respectively. Excluding cases as defined by a priori criteria, i.e. lesions located deeper than 35 mm, lesions larger than 35 mm, and retroareolar lesions, a sensitivity of 85.5% was observed, and for invasive cancers, 91.7%. The detection rate for ductal carcinoma in situ (DCIS) was poor (57.1%, n=14). By adding EIS to mammography and ultrasound, the sensitivity rose from 86.4 to 95.1%, whereas the accuracy decreased from 82.3 to 75.7%. EIS appears to be of interest as an adjunct to breast diagnostic techniques, performing with a reasonable sensitivity. Further investigations on histomorphological characteristics and the reasons for false-negative findings are essential to gain further knowledge about the bioelectricity of breast lesions, and prove the value of this new technology.

Differentiation of mammographically suspicious lesions: evaluation of breast ultrasound, MRI mammography and electrical impedance scanning as adjunctive technologies in breast cancer detection.

AIM: Various modalities are used as an adjunct to mammography for differentiation of potentially suspicious breast lesions. Electrical impedance scanning (EIS) is a new technique based upon the principle that cancer cells exhibit altered local dielectric properties and thus show measurably higher conductivity values. The accuracy of differentiation of benign and malignant breast lesions was evaluated to determine whether EIS duplicates or supplements the results obtainable from ultrasound (US) or magnetic resonance imaging (MRI). MATERIALS AND METHODS: One hundred mammographically suspicious lesions were examined using US, MRI and EIS. Definitive histology was acquired through either lesion biopsy or surgical excision. RESULTS: Fifty of 62 malignant lesions were correctly identified using EIS (81% overall sensitivity), 24/38 benign lesions were correctly identified as benign (63% specificity). Negative predictive value and positive predictive value of 67 and 78% were observed, respectively. kappa-factor evaluation revealed a value of 0.82 between MRI and EIS and 0.62 between US and EIS. CONCLUSIONS: EIS may be a valuable adjunct for differentiation of suspicious mammographic lesions. Based upon the calculated kappa-factor, EIS results supplement US examinations. Artifacts (superficial skin lesions, poor contact, air bubbles) currently result in the high false-positive rate of EIS.