Cherie M. Kuzmiak

Dedicated 3D photoacoustic breast imaging

PURPOSE To report the design and imaging methodology of a photoacoustic scanner dedicated to imaging hemoglobin distribution throughout a human breast. METHODS The authors developed a dedicated breast photoacoustic mammography (PAM) system using a spherical detector aperture based on our previous photoacoustic tomography scanner. The system uses 512 detectors with rectilinear scanning. The scan shape is a spiral pattern whose radius varies from 24 to 96 mm, thereby allowing a field of view that accommodates a wide range of breast sizes. The authors measured the contrast-to-noise ratio (CNR) using a target comprised of 1-mm dots printed on clear plastic. Each dot absorption coefficient was approximately the same as a 1-mm thickness of whole blood at 756 nm, the output wavelength of the Alexandrite laser used by this imaging system. The target was immersed in varying depths of an 8% solution of stock Liposyn II-20%, which mimics the attenuation of breast tissue (1.1 cm(-1)). The spatial resolution was measured using a 6 μm-diameter carbon fiber embedded in agar. The breasts of four healthy female volunteers, spanning a range of breast size from a brassiere C cup to a DD cup, were imaged using a 96-mm spiral protocol. RESULTS The CNR target was clearly visualized to a depth of 53 mm. Spatial resolution, which was estimated from the full width at half-maximum of a profile across the PAM image of a carbon fiber, was 0.42 mm. In the four human volunteers, the vasculature was well visualized throughout the breast tissue, including to the chest wall. CONCLUSIONS CNR, lateral field-of-view and penetration depth of our dedicated PAM scanning system is sufficient to image breasts as large as 1335 mL, which should accommodate up to 90% of the women in the United States.

A comparative study of mobile electronic data entry systems for clinical trials data collection

PURPOSE To determine the speed, accuracy, ease of use, and user satisfaction of various electronic data entry platforms for use in the collection of mammography clinical trials data. METHOD AND MATERIALS Four electronic data entry platforms were tested: standalone personal digital assistant (PDA), Tablet PC, digitizer Tablet/PDA Hybrid (DTP Hybrid), and digital pen (d-pen). Standard paper data entry was used as control. Each of five radiologist readers was assigned to enter interpretations for 20 screening mammograms using three out of the five data entry methods. Assistants recorded both start and stop data entry times of the radiologists and the number of help requests made. Data were checked for handwriting recognition accuracy for the d-pen platform using handwriting verification software. A user satisfaction survey was administered at the end of each platform reading session. RESULTS Tablet PC and d-pen were statistically equivalent to conventional pen and paper in initial data entry speed. Average verification time for d-pen was significantly less than secondary electronic data entry of paper forms (p-value <0.001). The number of errors in handwriting recognition for d-pen was less than secondary electronic data entry of the paper forms data. Users were most satisfied with Tablet PC, d-pen, and conventional pen and paper for data entry. CONCLUSIONS Tablet PC and d-pen are equally fast and easy-to-use data entry methods that are well tolerated by radiologist users. Handwriting recognition review and correction for the d-pen is significantly faster and more accurate than secondary manual keyboard and mouse data entry.

Comparison of Calcification Specificity in Digital Mammography Using Soft-Copy Display Versus Screen-Film Mammography

OBJECTIVE The purpose of this study was to compare specificity in the interpretation of calcifications in soft-copy reviewing of digital mammograms versus hard-copy reviewing of screen-film mammograms. MATERIALS AND METHODS A total of 130 consecutive cases with calcifications (44 malignant and 86 benign) that had been evaluated with needle or surgical biopsy were collected. Both screen-film mammography and soft-copy digital mammography were obtained in the same patients under existing research protocols using Fischer Imagings SenoScan (n = 71), Lorads digital mammography system (n = 35), and GE Healthcares Senographe 2000D (n = 24). Eight trained radiologists scored all lesions--cropped or masked to display just the region of interest--both on screen-film and soft-copy digital mammography with a month between reviews to reduce the effects of learning and memory. A 5-point malignancy scale was used, with 1 as definitely not, 2 as probably not, 3 as possibly, 4 as probably, and 5 as definitely. Reviewers were randomly assigned condition order, and images within each condition were randomly ordered. Repeated measures analysis of variance was used to test for differences between conditions in specificity computed via nonparametric receiver operating characteristic (ROC) study separately for each reviewer and condition. RESULTS Across all reviewers, the mean specificity for 1 or 2 versus 3, 4, or 5 was 0.803 for screen-film mammography (range, 0.413-0.938; SD +/- 0.166) and 0.833 for soft-copy image (range, 0.375-0.951; SD +/- 0.187). Although not statistically significant (Students t test p values from 0.19 to 0.99 across all cut points), numeric values of specificity were consistently higher for soft-copy versus screen-film mammography. No statistical significance in specificity was seen using all possible cut points in the 5-point scale, although the primary analysis used the cutpoint for differentiation between benign and malignant cases as 1 or 2 versus 3, 4, or 5. CONCLUSION No statistically significant difference was shown in specificity achievable using soft-copy digital versus screen-film mammography in this study.

Cancer Cases from ACRIN Digital Mammographic Imaging Screening Trial: Radiologist Analysis with Use of a Logistic Regression Model

PURPOSE To determine which factors contributed to the Digital Mammographic Imaging Screening Trial (DMIST) cancer detection results. MATERIALS AND METHODS This project was HIPAA compliant and institutional review board approved. Seven radiologist readers reviewed the film hard-copy (screen-film) and digital mammograms in DMIST cancer cases and assessed the factors that contributed to lesion visibility on both types of images. Two multinomial logistic regression models were used to analyze the combined and condensed visibility ratings assigned by the readers to the paired digital and screen-film images. RESULTS Readers most frequently attributed differences in DMIST cancer visibility to variations in image contrast--not differences in positioning or compression--between digital and screen-film mammography. The odds of a cancer being more visible on a digital mammogram--rather than being equally visible on digital and screen-film mammograms--were significantly greater for women with dense breasts than for women with nondense breasts, even with the data adjusted for patient age, lesion type, and mammography system (odds ratio, 2.28; P < .0001). The odds of a cancer being more visible at digital mammography--rather than being equally visible at digital and screen-film mammography--were significantly greater for lesions imaged with the General Electric digital mammography system than for lesions imaged with the Fischer (P = .0070) and Fuji (P = .0070) devices. CONCLUSION The significantly better diagnostic accuracy of digital mammography, as compared with screen-film mammography, in women with dense breasts demonstrated in the DMIST was most likely attributable to differences in image contrast, which were most likely due to the inherent system performance improvements that are available with digital mammography. The authors conclude that the DMIST results were attributable primarily to differences in the display and acquisition characteristics of the mammography devices rather than to reader variability.

The role of magnetic resonance imaging in diagnosis and management of breast cancer

A review of the literature on the current applications of breast magnetic resonance imaging (MRI) indications, their rationale and their place in diagnosis and management of breast cancer was given. Contrast-enhanced breast MRI is developing as a valuable adjunct to mammography and sonography. Its high sensitivity for invasive breast cancer establishes its superiority in evaluation of multifocality/multicentricity, tumor response to neoadjuvant chemotherapy, detection of recurrence, and staging. Emerging applications include spectroscopy, usage of new contrast agents, and MRI-guided interventions, including noninvasive treatment of breast cancer. Its potential benefit in screening high-risk women has yet to be established with prospective studies, particularly with regard to false positive results.

Future directions in breast imaging.

Breast cancer imaging has improved dramatically over the last decade, with higher and more uniform quality standards for mammography, the increasinguse of sonography and magnetic resonance imaging (MRI), and the widespread availability of imaging-guided percutaneous biopsy for clinically occult disease. This review paper describes the limitations that exist in the current state of the art for breast cancer imaging for detection and diagnosis. Four broad areas of future investigation are described in detail. First, we discuss the use of newer versions of mammography, such as digital mammography, with tomosynthesis and digital subtraction mammography. Secondly, new screening for occult disease might be improved through individualized strategies that stratify by patient risk, for example, through more rigorous screening with new and different tools for women at high risk. Third, the use of tools that might be useful for less invasive therapy of breast cancer with imaging to monitor the efficacy of the therapy is discussed. Finally, we describe the use of imaging tomonitor and adjust neoadjuvant chemotherapy regimens in the course of therapy for advanced breast cancers when the risk of death is high.

Assessing the Stand-Alone Sensitivity of Computer-Aided Detection With Cancer Cases From the Digital Mammographic Imaging Screening Trial

OBJECTIVE The purpose of this study was to assess the sensitivities and false-detection rates of two computer-aided detection (CADe) systems when applied to digital or film-screen mammograms in detecting the known breast cancer cases from the Digital Mammographic Imaging Screening Trial (DMIST) breast cancer screening population. MATERIALS AND METHODS Available film-screen and digital mammograms of 161 breast cancer cases from DMIST were analyzed by two CADe systems, iCAD Second-Look and R2 ImageChecker. Three experienced breast-imaging radiologists reviewed the CADe marks generated for each available cancer case, recording the number and locations of CADe marks and whether each CADe mark location corresponded with the known location of the cancer. RESULTS For the 161 cancer cases included in this study, the sensitivities of the DMIST reader without CAD were 0.43 (69/161, 95% CI 0.35-0.51) for digital and 0.41 (66/161, 0.33-0.49) for film-screen mammography. The sensitivities of iCAD were 0.74 (119/161, 0.66-0.81) for digital and 0.69 (111/161, 0.61-0.76) for film-screen mammography, both significantly higher than the DMIST study sensitivities (p < 0.0001 for both). The average number of false CADe marks per case of iCAD was 2.57 (SD, 1.92) for digital and 3.06(1.72) for film-screen mammography. The sensitivity of R2 was 0.74 (119/161, 0.66-0.81) for digital, and 0.60 (97/161, 0.52-0.68) for film-screen mammography, both significantly higher than the DMIST study sensitivities (p < 0.0001 for both). The average number of false CADe marks per case of R2 was 2.07 (1.57) for digital and 1.52 (1.45) for film-screen mammography. CONCLUSION Our results suggest the use of CADe in interpretation of digital and film-screen mammograms could lead to improvements in cancer detection.

Mammographic Findings of Partial Breast Irradiation

RATIONALE AND OBJECTIVES The aim of this study was to determine if patients who underwent partial-breast irradiation followed by segmental mastectomies had fewer mammographic changes on the first post-treatment mammogram than those who underwent segmental mastectomies followed by whole-breast irradiation. MATERIALS AND METHODS Subjects enrolled in a study of partial-breast irradiation therapy after segmental mastectomy (intraoperative radiation therapy) plus a random sample of patients who underwent segmental mastectomies followed by conventional whole-breast radiation therapy were identified through the institutions breast cancer database from March 2003 through February 2006. A radiologist specializing in breast imaging reviewed and recorded each patients pretreatment mammogram for breast density and tumor location and the first post-treatment mammogram, obtained within the first year of treatment, for three common types of mammographic change seen after breast surgery and radiation treatment (breast edema, skin thickening, and surgical scarring), which when severe make it difficult to use mammography for continuing follow-up of the conserved breast. The extent of mammographic change was noted by the radiologist as minimal, moderate, or marked. The data were entered into a database, and statistical analysis was conducted using logistic regression models and chi(2) tests. The effect of breast density on mammographic change was also assessed. RESULTS The severity of edema was lower with decreasing breast density (P < .006). There was no apparent effect of breast density on the severity of skin thickening. The extent of surgical scarring decreased as breast density increased (P < .026). Analysis of the data from the cumulative logistic regression models demonstrated that even after controlling for breast density, patients who underwent whole-breast radiation therapy had significantly more edema (P = .003), skin thickening (P = .003), and surgical scarring than those who underwent intraoperative radiation therapy (P < .001). CONCLUSION Patients have a higher probability of having fewer post-treatment mammographic changes after partial-breast irradiation followed by segmental mastectomy than after breast conservation surgery followed by whole-breast irradiation.

Whole Breast Ultrasound: Comparison of the Visibility of Suspicious Lesions with Automated Breast Volumetric Scanning Versus Hand-Held Breast Ultrasound

RATIONALE AND OBJECTIVES To assess how well radiologists visualize relevant features of lesions seen with automated breast volumetric scanning (ABVS) in comparison to hand-held breast ultrasound in women going to breast biopsy. MATERIALS AND METHODS Twenty-five subjects were recruited from women who were scheduled to undergo a breast biopsy for at least one Breast Imaging-Reporting and Data System four or five lesion identified in a diagnostic setting. In this institutional review board-approved study, the subjects underwent imaging of the breast(s) of concern using a dedicated system that allowed both hand-held breast ultrasound and ABVS. Five experienced breast radiologists reviewed the 30 lesions in 25 subjects in a reader study. Each reader was asked to specify the lesion type, size, imaging features, Breast Imaging-Reporting and Data System, and suspicion of malignancy and to compare the lesion characteristics of shape and margins between the two modalities. RESULTS Seven (23.3%) masses were malignant and 23 (76.4%) were benign. Across all lesions regardless of size or final pathology, there was no significant difference in sensitivity or specificity (P > .15) between the two modalities. For malignant lesions, the reader visualization confidence scores between the two ultrasound modalities were not significantly different (P > .1). However, analysis for nonmalignant cases showed a statistically significant increase in reader visualization confidence in lesion shape and margins (P < .001). CONCLUSIONS Radiologists showed increased confidence in visualization of benign masses and equal confidence in suspicious masses with ABVS imaging. This information could help decrease the need for additional hand-held imaging after automated whole breast ultrasound.

Development and initial demonstration of a low-dose dedicated fully 3d breast CT system

Based on earlier work demonstrating more complete, 3D cone beam sampling acquisition approaches that additionally facilitate chest wall imaging posterior to an uncompressed breast, a new, clinic-ready, low-dose breast CT system was developed and is undergoing initial clinical validation. The system includes a small focal spot pulsed x-ray source and 30x30cm2 flat panel detector having 3 degrees of freedom of motion, and a radiopaque patient support that facilitates whole-breast and universal anterior chest-wall imaging. Data is acquired with fully-3D trajectories and iteratively reconstructed within minutes of acquisition. Performance characteristics include: sub-200 micron isotropic reconstructed resolution, low-dose (<4.5 mGy) fully-3D scans acquired in ˜1.5 min, clinic throughput of 1patient/11min, and DICOM compatible images. To date, 25 subjects have been successfully scanned. Characterization results and volumetric clinical images are presented including demonstration of routine anterior chest wall imaging and comparison with digital mammography.