Akiko Shimauchi

US-guided Core Needle Biopsy of Axillary Lymph Nodes in Patients with Breast Cancer: Why and How to Do It

Axillary lymph node status is an extremely important prognostic factor in the assessment of new breast cancer patients. Sentinel lymph node biopsy is now often performed instead of axillary dissection for lymph node staging but raises numerous issues of practicality. Sentinel lymph node biopsy can be avoided if lymph node metastasis is documented presurgically, making an alternative staging method desirable. Although not widely performed for axillary lymph node staging, ultrasonography (US)-guided core needle biopsy is a well-established procedure for the breast and other organs, with a higher success rate in terms of tissue diagnosis than fine-needle aspiration biopsy. Improvements in US have established it as a valuable method for evaluating lymph nodes. US findings in abnormal lymph nodes include cortical thickening and diminished or absent hilum. In addition, color Doppler US of abnormal axillary lymph nodes often shows hyperemic blood flow in the hilum and central cortex or abnormal (nonhilar cortical) blood flow. US-guided core needle biopsy of axillary lymph nodes in breast cancer patients can yield a high accuracy rate with no significant complications, given the use of a biopsy device with controllable needle action, a clear understanding of anatomy, and good skills for controlling the needle.

Kinetic Curves of Malignant Lesions Are Not Consistent Across MRI Systems: Need for Improved Standardization of Breast Dynamic Contrast-Enhanced MRI Acquisition

OBJECTIVE The purpose of this study was to compare MRI kinetic curve data acquired with three systems in the evaluation of malignant lesions of the breast. MATERIALS AND METHODS The cases of 601 patients with 682 breast lesions (185 benign, 497 malignant) were selected for review. The malignant lesions were classified as ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and other. The dynamic MRI protocol consisted of one unenhanced and three to seven contrast-enhanced images acquired with one of three imaging protocols and systems. An experienced radiologist analyzed the shapes of the kinetic curves according to the BI-RADS lexicon. Several quantitative kinetic parameters were calculated, and the kinetic parameters of malignant lesions were compared across the three systems. RESULTS Imaging protocol and system 1 were used to image 304 malignant lesions (185 IDC, 62 DCIS); imaging protocol and system 2, 107 lesions (72 IDC, 21 DCIS); and imaging protocol and system 3, 86 lesions (64 IDC, 17 DCIS). Compared with those visualized with imaging protocols and systems 1 and 2, IDC lesions visualized with imaging protocol and system 3 had significantly less initial enhancement, longer time to peak enhancement, and a slower washout rate (p < 0.004). Only 47% of IDC lesions imaged with imaging protocol and system 3 exhibited washout type curves, compared with 75% and 74% of those imaged with imaging protocols and systems 2 and 1, respectively. The diagnostic accuracy of kinetic analysis was lowest for imaging protocol and system 3, but the difference was not statistically significant. CONCLUSION The kinetic curve data on malignant lesions acquired with one system showed significantly lower initial contrast uptake and a different curve shape in comparison with data acquired with the other two systems. Differences in k-space sampling, T1 weighting, and magnetization transfer effects may be explanations for the difference.

The diverse pathology and kinetics of mass, nonmass and focus enhancement on MR imaging of the breast

To compare the pathology and kinetic characteristics of breast lesions with focus‐, mass‐, and nonmass‐like enhancement.

Comparison of MDCT and MRI for Evaluating the Intraductal Component of Breast Cancer

OBJECTIVE The purpose of our study was to compare the accuracy of MDCT and MRI for evaluating the intraductal component of breast cancer. MATERIALS AND METHODS Sixty-nine patients with histologically proven invasive carcinoma underwent MDCT and MRI. Retrospectively, two radiologists performed a blinded review of the MDCT and MRI. Cases with intraductal component enhancement were classified into two morphologic types: ductal extension and segmental distribution. The lengths of the main tumor and of the intraductal component were measured in cases with ductal extension. For cases with segmental distribution, only the maximum length of the tumor was measured. RESULTS The sensitivity, specificity, and accuracy in detecting the intraductal component were 61%, 88%, and 71%, respectively, using MDCT; and 75%, 88%, and 80%, respectively, using MRI. MRI revealed the presence of the intraductal component with significantly higher sensitivity than did MDCT (p = 0.031). In the analysis of the length of the intraductal component in cases with ductal extension, which had relatively small intraductal components, underestimation by 15 mm or more was significantly less frequent with MRI than with MDCT (p = 0.008). There was no significant difference between MDCT and MRI in the evaluation of the maximum length of tumors in cases with segmental distribution, which had relatively large intraductal components. CONCLUSION Compared with MDCT, MRI revealed the presence of the intraductal component with higher sensitivity and equivalent specificity. In cases with ductal extension, MRI is more precise than MDCT for determination of the margin for surgical removal, with less underestimation of the extent of the intraductal component.

Breast Cancers Not Detected at MRI: Review of False-Negative Lesions

OBJECTIVE The objective of our study was to determine the sensitivity of cancer detection at breast MRI using current imaging techniques and to evaluate the characteristics of lesions with false-negative examinations. MATERIALS AND METHODS Two hundred seventeen patients with 222 newly diagnosed breast cancers or highly suspicious breast lesions that were subsequently shown to be malignant underwent breast MRI examinations for staging. Two breast imaging radiologists performed a consensus review of the breast MRI examinations. The absence of perceptible contrast enhancement at the expected site was considered to be a false-negative MRI. Histology of all lesions was reviewed by an experienced breast pathologist. RESULTS Enhancement was observed in 213 (95.9%) of the 222 cancer lesions. Of the nine lesions without visible enhancement, two lesions were excluded because the entire tumor had been excised at percutaneous biopsy performed before the MRI examination and no residual tumor was noted on the final histology. The overall sensitivity of MRI for the known cancers was 96.8% (213/220); for invasive cancer, 98.3% (176/179); and for ductal carcinoma in situ, 90.2% (37/41). CONCLUSION In a population of 220 sequentially diagnosed breast cancer lesions, we found seven (3.2%) MRI-occult cancers, fewer than seen in other published studies. Small tumor size and diffuse parenchymal enhancement were the principal reasons for these false-negative results. Although the overall sensitivity of cancer detection was high (96.8%), it should be emphasized that a negative MRI should not influence the management of a lesion that appears to be of concern on physical examination or on other imaging techniques.

Segmentation of suspicious lesions in dynamic contrast-enhanced breast MR images

Dynamic contrast enhanced breast MRI (DCE BMRI) is an emerging tool for breast cancer diagnosis. There is a clear clinical demand for computer-aided diagnosis (CADx) tools to support radiologists in the diagnostic reading process of DCE BMRI studies. A crucial step in a CADx system is the segmentation of tumors, which allows for accurate assessment of the 3D lesion size and morphology. In this paper we propose a semiautomatic segmentation procedure for suspicious breast lesions. The proposed methodology consists of four steps: (1) Robust seed point selection. This interaction mode ensures robustness of the segmentation result against variations in seed-point placement. (2) Automatic intensity threshold estimation in the subtraction image. (3)Connected component analysis based on the estimated threshold. (4) A post-processing step that includes non-enhancing portions of the lesion into the segmented area and removes attached vessels. The proposed methodology was applied to DCE BMRI data acquired at different institutions using different protocols.

Accuracy of axillary lymph node staging in breast cancer patients: an observer-performance study comparison of MRI and ultrasound.

PURPOSE To compare magnetic resonance imaging (MRI) and ultrasound (US) for axillary lymph node (LN) staging in breast cancer patients in an observer-performance study. MATERIALS AND METHODS An observer-performance study was conducted with five breast radiologists reviewing 50 consecutive patients of newly diagnosed invasive breast cancer with the use of ipsilateral axillary MRI and US. LN status was pathologically proved in all patients. Each observer reviewed the images in two separate sessions: one for MRI and the other for US. Observers were asked to indicate their confidence of the presence of at least one ipsilateral metastatic LN on a quasi-continuous rating scale and whether they recommend percutaneous biopsy preoperatively. Receiver operating characteristic (ROC) analysis and area under the ROC curve were used to characterize diagnostic performance. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated from whether observers recommended biopsy. RESULTS There were no statistically significant differences in each observers performance between MRI and US, or in the performance of all observers as a group, in terms of ROC analysis. There were no statistically significant differences in sensitivity, specificity, PPV, or NPV between MRI and US, but there were statistically significant improvements in specificity and PPV from either MRI or US alone to MRI and US combined. CONCLUSIONS Observer performance on MRI and US are comparable for axillary LN staging. When US and MRI are concordant for positive findings, higher specificity and PPV can be obtained.

Robust segmentation of mass-lesions in contrast-enhanced dynamic breast MR images.

To develop and evaluate a computerized segmentation method for breast MRI (BMRI) mass‐lesions.

Combined use of T2-weighted MRI and T1-weighted dynamic contrast–enhanced MRI in the automated analysis of breast lesions

A multiparametric computer‐aided diagnosis scheme that combines information from T1‐weighted dynamic contrast–enhanced (DCE)‐MRI and T2‐weighted MRI was investigated using a database of 110 malignant and 86 benign breast lesions. Automatic lesion segmentation was performed, and three categories of lesion features (geometric, T1‐weighted DCE, and T2‐weighted) were automatically extracted. Stepwise feature selection was performed considering only geometric features, only T1‐weighted DCE features, only T2‐weighted features, and all features. Features were merged with Bayesian artificial neural networks, and diagnostic performance was evaluated by ROC analysis. With leave‐one‐lesion‐out cross‐validation, an area under the ROC curve value of 0.77 ± 0.03 was achieved with T2‐weighted‐only features, indicating high diagnostic value of information in T2‐weighted images. Area under the ROC curve values of 0.79 ± 0.03 and 0.80 ± 0.03 were obtained for geometric‐only features and T1‐weighted DCE‐only features, respectively. When all features were considered, an area under the ROC curve value of 0.85 ± 0.03 was achieved. We observed P values of 0.006, 0.023, and 0.0014 between the geometric‐only, T1‐weighted DCE‐only, and T2‐weighted‐only features and all features conditions, respectively. When ranked, the P values satisfied the Holm–Bonferroni multiple‐comparison test; thus, the improvement of multiparametric computer‐aided diagnosis was statistically significant. A computer‐aided diagnosis scheme that combines information from T1‐weighted DCE and T2‐weighted MRI may be advantageous over conventional T1‐weighted DCE‐MRI computer‐aided diagnosis. Magn Reson Med, 2011.

Clinical implementation of a multislice high spectral and spatial resolution-based MRI sequence to achieve unilateral full-breast coverage

High-resolution, single-slice, high spatial and spectral resolution (HiSS) breast magnetic resonance imaging (MRI) provides improved lesion conspicuity, margin definition and internal definition, as compared to conventional clinical MRI - and thus may provide better lesion characterization and increase breast MRI specificity. Volumetric HiSS imaging is highly desirable, but was considered to be time-prohibitive. Specifically, the concern was that faster acquisition times -- necessitating a lower spectral resolution -- could compromise established advantages of HiSS imaging. In this pilot study, we demonstrate for the first time a fast, clinically practical, HiSS-based sequence that achieves full unilateral breast coverage, while preserving essential qualities of full-spectral resolution HiSS imaging. We imaged five patients of varying breast sizes at 1.5 T, with HiSS acquisitions performed after the standard clinical protocol, and lasting an average of 8.5 min. Maximum intensity projection (MIP) images of HiSS data were constructed and compared to MIPs of conventional clinical images. Single-slice images through three lesions were also compared. HiSS images achieved better fat suppression than the clinical fat-saturated sequence (fat signal SNR was reduced by 50% in HiSS images) as well as increased conspicuity, as assessed qualitatively by an experienced radiologist. Thus, we show that volumetric HiSS imaging can conserve the advantages of single-slice HiSS imaging and that further technical development of volumetric HiSS is desirable.