Electrical impedance scanning for classifying suspicious breast lesions: first results

It has long been established that cancer cells exhibit altered local dielectric properties compared with normal cells. Consequently, different electrical conductivity and capacitance are measurable in malignant vs normal tissues. In this study we evaluated the reliability of electrical impedance scanning (EIS), a new technology, for the classification of suspicious lesions: differentiating benign from malignant, and as a primary means of detection of breast cancer. Fifty-two women with 58 sonographically and/or mammographically suspicious findings were examined using electrical impedance scanning. Two different examination modes of TransScan TS2000 (Siemens, Erlangen, Germany), the standard-resolution mode for a routine overview examination, and the targeted high-resolution mode for a local examination of the suspicious lesion were used. All patients were additionally imaged by MR mammography (MRM) and underwent core-biopsy and/or surgical treatment after the EIS examination. With respect to the histopathological findings (29 malignant and 29 benign lesions) 27 of 29 (93.1 %) malignant lesions were correctly identified using the high-resolution mode of EIS, whereas 19 of 29 (65.5 %) benign lesions were correctly identified as benign (10 of 29 benign lesions showed as false-positive findings). Negative and positive predictive values of 90.5 and 73.0 % were observed, respectively. Using the standard-resolution mode 22 of 29 malignancies were correctly detected (sensitivity 75.9 %), whereas 22 of 29 were correctly identified as benign (specificity 72.4 %). Electrical impedance scanning appears to be a promising new technology providing a relatively high sensitivity for the verification of suspicious mammographic and/or sonographic lesions especially using the high-resolution mode for local examinations. Artifacts, such as signals from superficial skin lesions, poor contact, and air bubbles, are currently a limitation. Received: 10 February 2000; Revised: 29 May 2000; Accepted: 30 May 2000     

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.     

The negative predictive value of electrical impedance scanning in BI-RADS category IV breast lesions

OBJECTIVES: We sought to prospectively assess the value of electrical impedance scanning (EIS) in discriminating benign from malignant lesions classified as BI-RADS category IV in mammography in comparison with ultrasound (US), with a special focus on negative prediction. MATERIALS AND METHODS: EIS was performed on 128 BI-RADS category IV lesions in 121 women (mean, 51.8 years). The newly developed EIS software 2.67 calculates a BI-RADS-like level of suspicion (LOS) on a 5-grade scale. LOS 1, 2, and 3 were considered negative; LOS 4 and 5 were considered positive. Histopathologic results were obtained in all lesions. RESULTS: Histology proved 37 lesions malignant, 91 benign. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of EIS compared with US were 94.6%, 74.7%, 80.5%, 60.3%, 97.1% versus 90.5%, 33.8%, 47.2%, 29.7%, 92.0%, respectively. In 43 lesions sized < or = 10 mm, EIS demonstrated better sensitivity, specificity, accuracy, PPV, and NPV of 100%, 83.3%, 90.7%, 82.6%, and 100%, respectively. Although NPV was also high, US showed no sufficient results in 39 (30.5%) lesions because of microcalcifications. Receiver operating curve analysis revealed best results for a combined use of US and EIS. CONCLUSIONS: With a NPV of 97.1% of EIS in BI-RADS category IV breast lesions, a negative result in these lesions could be firm indication to manage them as BI-RADS-category III and refer patients for a 6-month short-interval follow-up rather than performing a biopsy. The best adjunctive diagnostic performance can be achieved by a combination of US and EIS. Costs and patient morbidity could be minimized.     

Adjunctive diagnostic value of targeted electrical impedance imaging to conventional methods in the evaluation of breast lesions

PURPOSE: To determine the diagnostic accuracy of targeted electrical impedance imaging in characterizing breast lesions, and to evaluate whether lesion size, depth and histopathology affect the diagnosis. MATERIAL AND METHODS: A total of 137 women with 145 lesions (79 malignant and 66 benign) found by palpation or mammography were prospectively enrolled in this study. The patients were examined by means of clinical breast examination, mammography, ultrasonography, and electrical impedance imaging with TransScan TS2000. A level of suspicion (LOS) post-processing algorithm (v2.67) was used for TS2000 lesion assessment. Imaging findings were correlated with cytologic (n=54) and histologic diagnoses (n=91). Patients with benign lesions were followed up for a mean of 36 months. RESULTS: TS2000 showed a high sensitivity (86%) which did not differ significantly from that of mammography (87%) and ultrasonography (US) (75%). The specificity of TS2000 (49%) was significantly lower compared to mammography (97%, P<0.0001) and US (100%, P<0.0001). The additive use of TS2000 to mammography and US yielded no significant increase in sensitivity (97%), but the decrease in specificity was significant (46%, P<0.0001). Diagnostic effectiveness of TS2000 (Az=0.68), as measured by the area under the ROC curve, was significantly lower than for mammography (Az=0.93, P<0.0001) and for US (Az=0.91, P<0.0001). When using TS2000 in addition to mammography and US (Az=0.86), a significant impairment was found (P=0.0003). CONCLUSION: The role of targeted electrical impedance imaging as an adjunct to mammography and ultrasonography in the diagnosis of breast lesions is not justified by the result of this study.     

Diagnostic interplay of proton magnetic resonance spectroscopy and diffusion weighted images with apparent diffusion coefficient values in suspicious breast lesions

Aim of the work

To study the diagnostic performance of combined single voxel 1H-MRS and DW-MRI with ADC values as a non-contrast diagnostic tool, compared to the DCE-MRI, in suspicious breast lesions.

Accuracy of MR imaging in the work-up of suspicious breast lesions: a diagnostic meta-analysis.

RATIONALE AND OBJECTIVES: The authors performed a systematic, critical review of the literature on magnetic resonance (MR) imaging for primary breast cancer detection in patients with suspicious breast lesions, analyzed MR test performance in the articles meeting study criteria, and used this information to examine the cost-effectiveness of preoperative MR imaging. MATERIALS AND METHODS: A structured, predefined MEDLINE search was conducted to identify potentially relevant, peer-reviewed, English-language references from January 1996 through August 1997 on the diagnostic accuracy of breast MR imaging. This information was supplemented by manually searching bibliographies of the retrieved articles for additional potentially relevant references. All studies were independently abstracted by two reviewers using a prospectively designed worksheet. Abstraction results were analyzed with the summary receiver operating characteristic (ROC) method. RESULTS: Of 41 identified studies, 16 met the inclusion criteria. These studies reported sensitivities ranging from 63% to 100% and specificities ranging from 21% to 100%. Maximum joint sensitivity and specificity of the summary ROC curve was 89% (95% confidence interval [CI]: 82%, 93%). At a sensitivity of 95%, specificity was 67%. When test performance values were applied to a previous cost-effectiveness analysis, the cost-effectiveness of preoperative MR imaging relative to that of excisional biopsy was confirmed, but its cost-effectiveness relative to that of needle core biopsy varied widely. CONCLUSION: For MR imaging to be a cost-effective alternative to excisional biopsy for diagnosis of suspicious breast lesions, its diagnostic test performance must be equal to or better than the best results in recently published studies.     

Non-palpable breast lesions. Diagnostic criteria and preoperative localization

Marking of non-palpable breast lesions for biopsy has become a routine procedure in patients in whom mammography has suggested malignancy. Between October 1981 and December 1985 a localization method was used in 123 patients. In 35 per cent of the biopsies a malignant lesion was disclosed. In patients with a mass only, malignancy was found in 37 per cent of the biopsies. If microcalcifications alone were the main reason for the biopsy, malignancy was disclosed in 25 per cent. If both a mass and microcalcifications were present, 52 per cent of the biopsies disclosed a malignant lesion.     

Influence of size and depth on accuracy of electrical impedance scanning

Cancer cells exhibit altered local dielectric properties which can be assessed using electrical impedance scanning (EIS). The study was aimed at clarifying influence of lesion size and depth on EIS performance. From a series of 387 lesions (129 malignant and 258 benign) from 363 patients being sonographically and/or mammographically evaluated, size and depth information was not available in 112 lesions, size was available in 86 lesions and additional depth information was available in 189 lesions, respectively, while performing EIS. Lesions were either histologically verified or had a follow-up of at least 2 years. One hundred three of 129 malignant lesions and 165 of 258 benign lesions were correctly detected (sensitivity 79.8%, specificity 64.0%, accuracy 71.9%). Sensitivity without knowledge of size and depth was 64.6% (10 of 16 malignant lesions detected). This value increased to 76.2% (32 of 42) with knowledge of the size and further increased to 85.9% with knowledge of size and depth (61 of 71). Specificity values in the three subgroups were almost similar: 64.6 (62 of 96), 65.9 (29 of 44), and 62.7% (74 of 118), respectively. Accuracy rises from 63.6% (without knowledge of size/depth) to 71.1 and 74.3% (with size knowledge and with size and depth knowledge, respectively). Accuracy of EIS improved significantly by including sonographical information about depth and size into the analysis. Ultrasound examination should be performed prior to EIS.     

Clinical and diagnostic value of preoperative MR mammography and FDG-PET in suspicious breast lesions

Dynamic enhanced magnetic resonance (MR) mammography and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) of the breast were directly compared preoperatively in suspicious breast lesions. Forty-two breast lesions in 40 patients were examined with a three-dimensional dynamic MR imaging series and FDG-PET. The MR and PET examinations were evaluated separately and the results were compared with the histological findings. The sensitivity and specificity of each method were calculated. The diagnostic value of both modalities as single diagnostic tool and in combination was investigated. Nineteen malignant and 23 benign breast lesions were proven histologically. Magnetic resonance mammography and FDG-PET showed a sensitivity of 89 and 63%, respectively. The specificity was 74 and 91%, respectively. The combination of both imaging methods decreased the not-required biopsies from 55 to 17%. Only one false-negative finding—a patient pre-treated with chemotherapy—was observed in both methods. The combination of MR mammography and FDG-PET can help to decrease biopsies of benign breast lesions. Because of their high cost, these modalities should only be used in problematic cases to either rule out or to demonstrate malignancy. The best diagnostic strategy is achieved using MR mammography first. If the diagnosis is still questionable, FDG-PET can be performed. This article was presented in part at the 4th Annual Meeting of the ISMRM, New York, 1996     

FDG PET and other imaging modalities in the primary diagnosis of suspicious breast lesions

Mammography is the primary imaging modality for screening of breast cancer and evaluation of breast lesions (T staging). Ultrasonography is an adjunctive tool for mammographically suspicious lesions, in patients with mastopathy and as guidance for reliable histological diagnosis with percutaneous biopsy. Dynamic enhanced magnetic resonance mammography (MRM) has a high sensitivity for the detection of breast cancer, but also a high false positive diagnosis rate. In the literature, MRM is reported to have a sensitivity of 86-96%, a specificity of 64-91%, an accuracy of 79-93%, a positive predictive value (PPV) of 77-92% and a negative predictive value (NPV) of 75-94%. In unclarified cases, metabolic imaging using fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) can be performed. In the literature, FDG PET is reported to have a sensitivity of 64-96%, a specificity of 73-100%, an accuracy of 70-97%, a PPV of 81-100% and an NPV of 52-89%. Furthermore, PET or PET/CT using FDG has an important role in the assessment of N and M staging of breast cancer, the prediction of tumour response in patients with locally advanced breast cancer receiving neoadjuvant chemotherapy, and the differentiation of scar and cancer recurrence. Other functional radionuclide-based diagnostic tools, such as scintimammography with sestamibi, peptide scintigraphy or immunoscintigraphy, have a lower accuracy than FDG PET and, therefore, are appropriate only for exceptional indications.     

Additional diagnostic value of MRI in patients with suspicious breast lesions based on ultrasound

Objective:

Biopsy has long been the standard approach in Breast Imaging Reporting and Data System® (BI-RADS) 4 or BI-RADS 5 (American College of Radiology, Reston, VA) lesions despite a wide variation in reported incidence of malignancy in BI-RADS 4 lesions. This study examined the diagnostic value of breast MRI as well as its ability to decrease unnecessary biopsies in patients with solid breast lesions who had an indication for biopsy.

Methods:

In this retrospective study, 277 breast lesions with a documented histological diagnosis as established by ultrasound-guided biopsy were included. All patients were female, and biopsy was performed owing to a BI-RADS score of 4 or 5 on ultrasonography. In addition, all patients had undergone MRI before biopsy. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MRI in predicting malignancy were calculated.

Results:

When all lesions were analysed, sensitivity, specificity, NPV and PPV of MRI in detecting malignancy were 94.2%, 56.1%, 90.7% and 68.1%, respectively. When only ultrasonographic BI-RADS 4 lesions are considered, the corresponding figures were as follows: 90.9%, 56.7%, 93.8% and 46.4%, respectively. False-negative rate of MRI for the latter group of lesions was 2.6%. 42% of unnecessary biopsies were avoided in sonographic BI-RADS 4 lesions.

Conclusion:

Despite promising results obtained in this study, dynamic MRI currently does not seem to be effective in ruling out the need for biopsy in the assessment of sonographic BI-RADS 4 lesions. However, advanced MRI techniques may assist in improving possible benefits of MRI in this patient group.According to data from the American Cancer Society, Atlanta, GA, benign lesions account for nearly 80% of all breast biopsies performed. Although mammography is effective in detecting occult breast cancer, it is also associated with false-positive findings, resulting in the detection of different types of benign tissue in approximately 71–75% of the cases undergoing biopsy owing to suspicious mammography.¹ This usually prompts the clinicians to use ultrasound or MRI to obtain additional information on the character of the lesions. However, this approach has resulted in higher cancer detection yields in females who are at increased risk of breast cancer at the expense of increased false-positivity rates.^2,3Although it may be appropriate to monitor Breast Imaging Reporting and Data System® (BI-RADS) 3 (American College of Radiology, Reston, VA) (probably benign) lesions radiologically owing to their low cancer risk (0.3–1.7%),^4–8 biopsy has long been the standard approach in BI-RADS 4 or BI-RADS 5 lesions. The reported risk of malignancy for BI-RADS 5 lesions is >95%, while a wide variation in reported incidence of malignancy is noted in BI-RADS 4 lesions (from 2% to 95%). Biopsy is recommended for any lesion with an estimated risk of malignancy exceeding 2% based on imaging findings. Therefore, most of the solid lesions visualized through imaging modalities are candidates for biopsy. In recent years, a good deal of research has been devoted to the combined use of different imaging modalities in order to decrease false-positive biopsies and to improve the well-known low specificity of radiological imaging techniques in general and ultrasound in particular. In this regard, breast MRI has been shown to provide a high negative predictive value (NPV) that may help safely exclude a diagnosis of malignancy.^9–12In this study, the diagnostic value of breast MRI as well as its ability to decrease unnecessary biopsies has been examined in a group of patients with solid breast lesions who had an indication for biopsy based on ultrasound results.     

Indeterminate or suspicious breast lesions detected initially with MR imaging: value of MRI-directed breast ultrasound

RATIONALE AND OBJECTIVES: To retrospectively determine the value of magnetic resonance imaging (MRI)-directed breast ultrasonography (US) in the evaluation of indeterminate or suspicious lesions identified on contrast-enhanced, breast MRI. MATERIALS AND METHODS: A total of 395 patients presenting for breast MRI during a 4-year period was retrospectively reviewed. Seventy-one patients were recommended for MRI-directed US for further characterization of indeterminate or suspicious breast lesions detected on MRI. Fifty-five patients (all female; age 31-80 years) had US. Their MRI and US were reviewed and tested for correlations with histologic results or long term follow-up. Logistic regression analyses were used to test for associations between MRI lesion characteristics and US detection rate. RESULTS: US identified 46 of 97 (47%) lesions depicted at MRI from 55 patients (47 [85%] of these patients had histories of breast malignancies). Twelve cancers were found from the 97 lesions (12%). Biopsy was avoidable in 10 lesions (10%). The detection rate with US was slightly higher with "mass" (55% [23/42]) lesions described in MRI than "non-mass" lesions or lymph nodes (42% [23/55]). There was a significant positive association (odd ratio = 1.23: 95% CI = 1.05-1.43, P = .01) between US detection rate and MRI mass lesion size. There was no statistical significance between US detection rate and the presence of malignancies; 42% (5/12) of MRI malignant lesions were not visualized with US. CONCLUSIONS: MRI-directed US reduced the number of biopsies required for indeterminate or suspicious MRI lesions. Nevertheless, the lesions which were biopsied had a low rate of malignancy.     

MRI-guided needle localization of suspicious breast lesions: results of a freehand technique

Magnetic resonance imaging (MRI) can detect clinically and mammographically occult breast lesions. In this study we report the results of MRI-guided needle localization of suspicious breast lesions by using a freehand technique. Preoperative MRI-guided single-needle localization was performed in 220 patients with 304 MRI-only breast lesions at our hospital between January 1997 and July 2004. Procedures were performed in an open 0.5-T Signa-SP imager allowing real-time monitoring, with patient in prone position, by using a dedicated breast coil. MRI-compatible hookwires were placed in a noncompressed breast by using a freehand technique. MRI findings were correlated with pathology and follow-up. MRI-guided needle localization was performed for a single lesion in 150 patients, for two lesions in 56 patients, and for three lesions in 14 patients. Histopathologic analysis of these 304 lesions showed 104 (34%) malignant lesions, 51 (17%) high-risk lesions, and 149 (49%) benign lesions. The overall lesion size ranged from 2.0–65.0 mm (mean 11.2 mm). No direct complications occurred. Follow-up MRI in 54 patients showed that two (3.7%) lesions were missed by surgical biopsy. MRI-guided freehand needle localization is accurate and allows localization of lesions anterior in the breast, the axillary region, and near the chest wall.     

Revaluation of breast cytology with pathologist on-site of lesions with suspicious sonographic features

Objective

Evaluating correlation estimation between diagnostic ultrasound (U.S.) of breast lesions and fine needle aspiration cytology (FNAC), and the correlation between cytology and histology (I) of these lesions undergo surgery.

Materials and methods

In 2010 we performed 1589 ultrasound breast. We identified 210 suspicious lesions to be subjected to FNAC, which was performed with pathologist on site, and extemporaneous analysis of the sample to assess their appropriateness. We classified the lesions in 5 ultrasound (U) classes according to the criteria defined by Echographic BIRADS Lexicon. The results of cytology were classified in 5 classes (C) according to the guidelines of F.O.N.Ca.M. Then we evaluated the diagnostic correlation between U.S. and FNAC, and between FNAC and Histology.

Results

The distribution of lesions in U classes was: 57U2, 55U3, 36U4 and 62U5. The diagnostic concordance between U and FNAC was 96.7%, with a sensitivity of 98%, specificity 93%, negative and positive predictive value respectively of 94.9% and 97.3%, and diagnostic accuracy of 96.6%. The 98 patients with C4-C5 lesions were subjected to surgery and the histology confirmed high-grade malignancy of lesions with a concordance of 99.7%.

Conclusions

Having achieved high diagnostic concordance between U and FNAC, and then between FNAC and histology, we may say that the FNAC, less invasive and traumatic for the patient than needle biopsy (CB), may be still a valid method when performed with pathologist on-site to assess the adequacy of the sample taken.     

Magnetic resonance-guided biopsy of suspicious breast lesions with a handheld vacuum biopsy device

Purpose: To evaluate a handheld vacuum-assisted device system for magnetic resonance image (MRI)-guided breast lesion biopsy.

Material and Methods: In 32 patients, a total of 42 suspicious breast lesions (mean diameter 7.5 mm for mass lesions, 11.6 mm for non-masslike diffuse lesions) seen with MRI (no suspicious changes in breast ultrasound or mammography) were biopsied (27 lateral, 15 medial) using a 10G vacuum-assisted breast biopsy device under MR guidance. Histology of biopsy specimens was compared with final histology after surgery or follow-up in benign lesions.

Results: In all biopsies, technical success was achieved. Histology revealed 11 lesions with ductal carcinoma in situ (DCIS) or invasive cancer, three with intermediate lesions (LCIS) and 28 with benign breast lesions (adenosis, infected hematoma). In one patient with discordant results of MRI and histology, surgical excision revealed medullary cancer. In the follow-up (mean 18 months) of the histological benign lesions, no breast cancer development was observed. Besides minor complications (hematoma, n = 6), with no further therapeutic interventions, no complications occurred.

Conclusion: MRI-guided breast lesion biopsy using a handheld vacuum-assisted device is a safe and effective method for the work-up of suspicious lesions seen with breast MRI without changes in mammography or ultrasound. In the case of discordant histology of vacuum biopsy and breast MRI appearance, surgical excision is recommended.