Variability of Postsurgical Imaging Surveillance of Breast Cancer Patients: A Nationwide Survey Study.

OBJECTIVE: Because of observed clinical variance and the discretion of referring physicians and radiologists in patient follow-up, the purpose of this study was to conduct a survey to explore whether broad discrepancy exists in imaging protocols used for postsurgical surveillance. SUBJECTS AND METHODS: An online survey was created to assess radiologists' use of diagnostic versus screening mammography for women with a personal history of breast cancer and determine whether the choice of protocol was associated with practice characteristics (setting, region, and reader type). RESULTS: Of 8170 surveys sent, 849 (10%) completed responses were returned. Seventy-nine percent of respondents recommended initial diagnostic mammography after lumpectomy (65% at 6 months, 14% at 12 months); 49% recommended diagnostic surveillance for up to 2 years before a return to screening mammography; and 33% continued diagnostic surveillance for 2-5 years before returning to screening. For imaging after mastectomy, 57% of respondents recommended diagnostic mammography of the unaffected breast. Among the 57%, however, 37% recommended diagnostic screening for only the first postmastectomy follow-up evaluation, and the other 20% permanently designated patients for diagnostic mammography after mastectomy. CONCLUSION: The optimal surveillance mammography regimen must be better defined. This preliminary study showed variability in diagnostic versus screening surveillance mammography for women with a history of breast cancer. Future studies should evaluate why these variations occur and how to standardize recommendations to tailor personalized imaging.

Can Breast Compression Be Reduced in Digital Mammography and Breast Tomosynthesis?

OBJECTIVE: The objective of this study was to investigate the impact of decreasing breast compression during digital mammography and breast tomosynthesis (DBT) on perceived pain and image quality. MATERIALS AND METHODS: In this two-part study, two groups of women with prior mammograms were recruited. In part 1, subjects were positioned for craniocaudal (CC) and mediolateral oblique (MLO) views, and four levels of compression force were applied to evaluate changes in breast thickness, perceived pain, and relative tissue coverage. No imaging was performed. In part 2, two MLO DBT images of one breast of each patient were acquired at standard and reduced compression. Blurring artifacts and tissue coverage were judged by three breast imaging radiologists, and compression force, breast thickness, relative tissue coverage, and perceived pain were recorded. RESULTS: Only the first reduction in force was feasible because further reduction resulted in inadequate breast immobilization. Mean force reductions of 48% and 47% for the CC and MLO views, respectively, resulted in a significantly reduced perceived pain level, whereas the thickness of the compressed breast increased by 0.02 cm (CC view) and 0.09 (MLO view, part 1 of the study) and 0.38 cm (MLO view, part 2 of the study), respectively, with no change in tissue coverage or increase in motion blurring. CONCLUSION: Mammography and DBT acquisitions may be possible using half of the compression force used currently, with a significant and substantial reduction in perceived pain with no clinically significant change in breast thickness and tissue coverage.

Does Preoperative MRI Workup Affect Mastectomy Rates and/or Re-excision Rates in Patients with Newly Diagnosed Breast Carcinoma? A Retrospective Review.

The purpose of this study is to determine whether including breast magnetic resonance imaging (MRI) in the preoperative workup of patients with known breast cancer has an impact on mastectomy and/or re-excision rates. This is an Institutional Review Board approved HIPAA compliant retrospective study reviewing the impact MRI has on mastectomy and re-excision rates in patients with newly diagnosed breast cancer. Our study compares two groups: (i) 154 patients who did not receive preoperative MRIs and served as a control group and (ii) 96 patients who received preoperative breast MRIs. Patient race and age between the two populations were not statistically different. The difference in mastectomy rates between the two populations was 10.7%; although not statistically different, the p value of 0.10 suggests a trend toward significance. The re-excision rates between the two populations, however, were significantly different (p < 0.001), with women in the control group having a higher re-excision rate than those in the study group. The difference between involved and clear margins was significant as well (p = 0.002), with patients undergoing preoperative MRI more likely to have negative margins. Preoperative breast MRI significantly decreases the likelihood of involved margins as well as the need for surgical re-excision. Preoperative breast MRI does not result in a statistically significant difference in mastectomy rates, although further investigation is required to determine whether there is a trend towards statistical significance.

Stereoscopic digital mammography: improved specificity and reduced rate of recall in a prospective clinical trial.

PURPOSE: To compare stereoscopic digital mammography (DM) with standard DM for the rate of patient recall and the detection of cancer in a screening population at elevated risk for breast cancer. MATERIALS AND METHODS: Starting in September 2004 and ending in December 2007, this prospective HIPAA-compliant, institutional review board-approved screening trial, with written informed consent, recruited female patients at elevated risk for breast cancer (eg, personal history of breast cancer or breast cancer in a close relative). A total of 1298 examinations from 779 patients (mean age, 58.6 years; range, 32-91 years) comprised the analyzable data set. A paired study design was used, with each enrolled patient serving as her own control. Patients underwent both DM and stereoscopic DM examinations in a single visit, findings of which were interpreted independently by two experienced radiologists, each using a Breast Imaging Reporting and Data System (BI-RADS) assessment (BI-RADS category 0, 1, or 2). All patients determined to have one or more findings with either or both modalities were recalled for standard diagnostic evaluation. The results of 1-year follow-up or biopsy were used to determine case truth. RESULTS: Compared with DM, stereoscopic DM showed significantly higher specificity (91.2% [1167 of 1279] vs 87.8% [1123 of 1279]; P = .0024) and accuracy (90.9% [1180 of 1298] vs 87.4% [1135 of 1298]; P = .0023) for detection of cancer. Sensitivity for detection of cancer was not significantly different for stereoscopic DM (68.4% [13 of 19]) compared with DM (63.2% [12 of 19], P .99). The recall rate for stereoscopic DM was 9.6% (125 of 1298) and that for DM was 12.9% (168 of 1298) (P = .0018). CONCLUSION: Compared with DM, stereoscopic DM significantly improved specificity for detection of cancer, while maintaining comparable sensitivity. The recall rate was significantly reduced with stereoscopic DM compared with DM. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120382/-/DC1.

Dosimetric characterization of a dedicated breast computed tomography clinical prototype.

PURPOSE: To investigate the glandular dose magnitudes and characteristics resulting from image acquisition using a dedicated breast computed tomography (BCT) clinical prototype imaging system. METHODS: The x-ray spectrum and output characteristics of a BCT clinical prototype (Koning Corporation, West Henrietta, NY) were determined using empirical measurements, breast phantoms, and an established spectrum model. The geometry of the BCT system was replicated in a Monte Carlo-based computer simulation using the GEANT4 toolkit and was validated by comparing the simulated results for exposure distribution in a standard 16 cm CT head phantom with those empirically determined using a 10 cm CT pencil ionization chamber and dosimeter. The computer simulation was further validated by replicating the results of a previous BCT dosimetry study. Upon validation, the computer simulation was modified to include breasts of varying sizes and homogeneous compositions spanning those encountered clinically, and the normalized mean glandular dose resulting from BCT was determined. Using the system's measured exposure output determined automatically for breasts of different size and density, the mean glandular dose for these breasts was computed and compared to the glandular dose resulting from mammography. Finally, additional Monte Carlo simulations were performed to study how the glandular dose values vary within the breast tissue during acquisition with both this BCT prototype and a typical craniocaudal (CC) mammographic acquisition. RESULTS: This BCT prototype uses an x-ray spectrum with a first half-value layer of 1.39 mm Al and a mean x-ray energy of 30.3 keV. The normalized mean glandular dose for breasts of varying size and composition during BCT acquisition with this system ranges from 0.278 to 0.582 mGy/mGy air kerma with the reference air kerma measured in air at the center of rotation. Using the measured exposure outputs for the tube currents automatically selected by the system for the breasts of different sizes and densities, the mean glandular dose for a BCT acquisition with this prototype system varies from 5.6 to 17.5 mGy, with the value for a breast of mean size and composition being 17.06 mGy. The glandular dose throughout the breast tissue of this mean breast varies by up to +/- 50% of the mean value. During a typical CC view mammographic acquisition of an equivalent mean breast, which typically results in a mean glandular dose of 2.0-2.5 mGy, the glandular dose throughout the breast tissue varies from approximately 15% to approximately 400% of the mean value. CONCLUSIONS: Acquisition of a BCT image with the automated tube output settings for a mean breast with the Koning Corp. clinical prototype results in mean glandular dose values approximately equivalent to three to five two-view mammographic examinations for a similar breast. For all breast sizes and compositions studied, this glandular dose ratio between acquisition with this BCT prototype and two-view mammography ranges from 1.4 to 7.2. In mammography, portions of the mean-sized breast receive a considerably higher dose than the mean value for the whole breast. However, only a small portion of a breast undergoing mammography would receive a glandular dose similar to that from BCT.

The positive predictive value of BI-RADS microcalcification descriptors and final assessment categories.

OBJECTIVE: The purpose of this article is to retrospectively assess the likelihood of malignancy of microcalcifications according to the BI-RADS descriptors in a digital mammography environment. MATERIALS AND METHODS: The study included 146 women with calcifications who underwent imaging-guided biopsy between April 2005 and July 2006. Digital mammograms procured before biopsy were analyzed independently by two breast imaging subspecialists blinded to biopsy results. Lesions described discordantly were settled by consensus. One of the radiologists provided a BI-RADS final assessment score. RESULTS: The overall positive predictive value of biopsies was 28.8%. The individual morphologic descriptors predicted the risk of malignancy as follows: fine linear/branching, 16 (70%) of 23 cases; fine pleomorphic, 14 (28%) of 50 cases; coarse heterogeneous, two (20%) of 10 cases; amorphous, 10 (20%) of 51 cases; and typically benign, zero (0%) of 12 cases. Fisher-Freeman-Halton exact testing showed statistical significance among morphology descriptors (p < 0.001) and distribution descriptors (p < 0.001). The positive predictive value for malignancy according to BI-RADS assessment categories were as follows: category 2, 0%; category 3, 0%; category 4A, 13%; category 4B, 36%; category 4C, 79%; and category 5, 100%. CONCLUSION: BI-RADS morphology and distribution descriptors can aid in assessing the risk of malignancy of microcalcifications detected on full-field digital mammography. The positive predictive value increased in successive BI-RADS categories (4A, 4B, and 4C), verifying that subdivision provides an improved assessment of suspicious microcalcifications in terms of likelihood of malignancy.

Comparison of soft-copy and hard-copy reading for full-field digital mammography.

PURPOSE: To compare radiologists' performance in detecting breast cancer when reading full-field digital mammographic (FFDM) images either displayed on monitors or printed on film. MATERIALS AND METHODS: This study received investigational review board approval and was HIPAA compliant, with waiver of informed consent. A reader study was conducted in which 26 radiologists read screening FFDM images displayed on high-resolution monitors (soft-copy digital) and printed on film (hard-copy digital). Three hundred thirty-three cases were selected from the Digital Mammography Image Screening Trial screening study (n = 49,528). Of these, 117 were from patients who received a diagnosis of breast cancer within 15 months of undergoing screening mammography. The digital mammograms were displayed on mammographic workstations and printed on film according to the manufacturer's specifications. Readers read both hard-copy and soft-copy images 6 weeks apart. Each radiologist read a subset of the total images. Twenty-two readers were assigned to evaluate images from one of three FFDM systems, and four readers were assigned to evaluate images from two mammographic systems. Each radiologist assigned a malignancy score on the basis of overall impression by using a seven-point scale, where 1 = definitely not malignant and 7 = definitely malignant. RESULTS: There were no significant differences in the areas under the receiver operating characteristic curves (AUCs) for the primary comparison. The AUCs for soft-copy and hard-copy were 0.75 and 0.76, respectively (95% confidence interval: -0.04, 0.01; P = .36). Secondary analyses showed no significant differences in AUCs on the basis of manufacturer type, lesion type, or breast density. CONCLUSION: Soft-copy reading does not provide an advantage in the interpretation of digital mammograms. However, the display formats were not optimized and display software remains an evolving process, particularly for soft-copy reading.

Monte Carlo and phantom study of the radiation dose to the body from dedicated CT of the breast.

PURPOSE: To prospectively determine the radiation dose absorbed by the organs and tissues of the body during a dedicated breast computed tomography (CT) study by using Monte Carlo methods and a phantom. MATERIALS AND METHODS: By using the Geant4 Monte Carlo tool kit, the Cristy anthropomorphic phantom and the geometry of a dedicated breast CT prototype were simulated. The simulation was used to track x-rays emitted from the source until their complete absorption or exit from the simulation limits. The interactions of the x-rays with the 65 different volumes representing organs, bones, and other tissues of the phantom that resulted in energy deposition were recorded. These data were used to compute the radiation dose to the organs and tissues during a complete dedicated breast CT scan relative to the average glandular dose to the imaged breast (relative organ dose [ROD]), by using the x-ray spectra proposed for dedicated breast CT imaging. The effectiveness of a lead shield for reducing the dose to the organs was investigated. RESULTS: The maximum ROD among the organs was for the ipsilateral lung with a maximum ROD of 3.25%, followed by ROD for the heart and the thymus. Of the skeletal tissues, the sternum received the highest dose with a maximum ROD to the bone marrow of 2.24% and to the bone surface of 7.74%. The maximum ROD to the uterus, representative of that of an early-stage fetus, was 0.026%. These maxima occurred for the highest-energy x-ray spectrum (80 kVp) that was analyzed. A lead shield does not substantially protect the organs that receive the highest dose from dedicated breast CT. CONCLUSION: Although the dose to the organs from dedicated breast CT is substantially higher than that from planar mammography, it is comparable to or considerably lower than that reached by other radiographic procedures and much lower than that of other CT examinations.

Radiation dose to organs and tissues from mammography: Monte Carlo and phantom study.

PURPOSE: To prospectively determine the radiation dose to the organs of the body during standard bilateral two-view mammography by using Monte Carlo simulations and a phantom. MATERIALS AND METHODS: A modified version of the Cristy mathematic anthropomorphic phantom was implemented in the Geant4 Monte Carlo tool kit to simulate the conditions present in screen-film and digital mammography. The breast was simulated with compression in both the craniocaudal and the mediolateral oblique views. X-rays were tracked from the source until their absorption in the body or in the detector or their exit from the simulation limits, with recording of all the intermediate interactions in the body. The simulation was performed with x-rays of energy ranging from 6 to 35 keV to obtain results for clinically relevant spectra. The ratio of dose to an organ in the body per unit glandular dose to the breast, denoted the relative organ dose (ROD), was computed. The effect of using a body protective shield was also investigated. RESULTS: The organs that received an ROD of 0.10% or higher in at least one view and one spectrum were the contralateral breast, ipsilateral eye and eye lens, heart, ipsilateral lung, and thymus. Among the organs, the maximum ROD was 0.62%. The maximum ROD for the bone surfaces was 2.36% and that for the red bone marrow was 0.56%. The highest ROD measured for the uterus or fetus at the first trimester was less than 10(-5). CONCLUSION: The radiation dose to all tissues other than the breast is extremely low. The dose to the first-trimester fetus is minimal.

Accuracy of soft-copy digital mammography versus that of screen-film mammography according to digital manufacturer: ACRIN DMIST retrospective multireader study.

PURPOSE: To retrospectively compare the accuracy for cancer diagnosis of digital mammography with soft-copy interpretation with that of screen-film mammography for each digital equipment manufacturer, by using results of biopsy and follow-up as the reference standard. MATERIALS AND METHODS: The primary HIPAA-compliant Digital Mammographic Imaging Screening Trial (DMIST) was approved by the institutional review board of each study site, and informed consent was obtained. The approvals and consent included use of data for future HIPAA-compliant retrospective research. The American College of Radiology Imaging Network DMIST collected screening mammography studies performed by using both digital and screen-film mammography in 49 528 women (mean age, 54.6 years; range, 19-92 years). Digital mammography systems from four manufacturers (Fischer, Fuji, GE, and Hologic) were used. For each digital manufacturer, a cancer-enriched reader set of women screened with both digital and screen-film mammography in DMIST was constructed. Each reader set contained all cancer-containing studies known for each digital manufacturer at the time of reader set selection, together with a subset of negative and benign studies. For each reader set, six or 12 experienced radiologists attended two randomly ordered reading sessions 6 weeks apart. Each radiologist identified suspicious findings and rated suspicion of breast cancer in identified lesions by using a seven-point scale. Results were analyzed according to digital manufacturer by using areas under the receiver operating characteristic curve (AUCs), sensitivity, and specificity for soft-copy digital and screen-film mammography. Results for Hologic digital are not presented owing to the fact that few cancer cases were available. The implemented design provided 80% power to detect average AUC differences of 0.09, 0.08, and 0.06 for Fischer, Fuji, and GE, respectively. RESULTS: No significant difference in AUC, sensitivity, or specificity was found between Fischer, Fuji, and GE soft-copy digital and screen-film mammography. Large reader variations occurred with each modality. CONCLUSION: No statistically significant differences were found between soft-copy digital and screen-film mammography for Fischer, Fuji, and GE digital mammography equipment.

Diagnostic accuracy of digital versus film mammography: exploratory analysis of selected population subgroups in DMIST.

PURPOSE: To retrospectively compare the accuracy of digital versus film mammography in population subgroups of the Digital Mammographic Imaging Screening Trial (DMIST) defined by combinations of age, menopausal status, and breast density, by using either biopsy results or follow-up information as the reference standard. MATERIALS AND METHODS: DMIST included women who underwent both digital and film screening mammography. Institutional review board approval at all participating sites and informed consent from all participating women in compliance with HIPAA was obtained for DMIST and this retrospective analysis. Areas under the receiver operating characteristic curve (AUCs) for each modality were compared within each subgroup evaluated (age < 50 vs 50-64 vs >or= 65 years, dense vs nondense breasts at mammography, and pre- or perimenopausal vs postmenopausal status for the two younger age cohorts [10 new subgroups in toto]) while controlling for multiple comparisons (P < .002 indicated a significant difference). All DMIST cancers were evaluated with respect to mammographic detection method (digital vs film vs both vs neither), mammographic lesion type (mass, calcifications, or other), digital machine type, mammographic and pathologic size and diagnosis, existence of prior mammographic study at time of interpretation, months since prior mammographic study, and compressed breast thickness. RESULTS: Thirty-three centers enrolled 49 528 women. Breast cancer status was determined for 42,760 women, the group included in this study. Pre- or perimenopausal women younger than 50 years who had dense breasts at film mammography comprised the only subgroup for which digital mammography was significantly better than film (AUCs, 0.79 vs 0.54; P = .0015). Breast Imaging Reporting and Data System-based sensitivity in this subgroup was 0.59 for digital and 0.27 for film mammography. AUCs were not significantly different in any of the other subgroups. For women aged 65 years or older with fatty breasts, the AUC showed a nonsignificant tendency toward film being better than digital mammography (AUCs, 0.88 vs 0.70; P = .0025). CONCLUSION: Digital mammography performed significantly better than film for pre- and perimenopausal women younger than 50 years with dense breasts, but film tended nonsignificantly to perform better for women aged 65 years or older with fatty breasts.

Glandular radiation dose in tomosynthesis of the breast using tungsten targets.

With the advent of new detector technology, digital tomosynthesis imaging of the breast has, in the past few years, become a technique intensely investigated as a replacement for planar mammography. As with all other x-ray-based imaging methods, radiation dose is of utmost concern in the development of this new imaging technology. For virtually all development and optimization studies, knowledge of the radiation dose involved in an imaging protocol is necessary. A previous study characterized the normalized glandular dose in tomosynthesis imaging and its variation with various breast and imaging system parameters. This characterization was performed with x-ray spectra generated by molybdenum and rhodium targets. In the recent past, many preliminary patient studies of tomosynthesis imaging have been reported in which the x-ray spectra were generated with x-ray tubes with tungsten targets. The differences in x-ray distribution among spectra from these target materials make the computation of new normalized glandular dose values for tungsten target spectra necessary. In this study we used previously obtained monochromatic normalized glandular dose results to obtain spectral results for twelve different tungsten target x-ray spectra. For each imaging condition, two separate values were computed: the normalized glandular dose for the zero degree projection angle (DgN0), and the ratio of the glandular dose for non-zero projection angles to the glandular dose for the zero degree projection (the relative glandular dose, RGD(alpha)). It was found that DgN0 is higher for tungsten target x-ray spectra when compared with DgN0 values for molybdenum and rhodium target spectra of both equivalent tube voltage and first half value layer. Therefore, the DgN0 for the twelve tungsten target x-ray spectra and different breast compositions and compressed breast thicknesses simulated are reported. The RGD(alpha) values for the tungsten spectra vary with the parameters studied in a similar manner to that found for the molybdenum and rhodium target spectra. The surface fit equations and the fit coefficients for RGD(alpha) included in the previous study were also found to be appropriate for the tungsten spectra.

Scatter radiation in digital tomosynthesis of the breast.

Digital tomosynthesis of the breast is being investigated as one possible solution to the problem of tissue superposition present in planar mammography. This imaging technique presents various advantages that would make it a feasible replacement for planar mammography, among them similar, if not lower, radiation glandular dose to the breast; implementation on conventional digital mammography technology via relatively simple modifications; and fast acquisition time. One significant problem that tomosynthesis of the breast must overcome, however, is the reduction of x-ray scatter inclusion in the projection images. In tomosynthesis, due to the projection geometry and radiation dose considerations, the use of an antiscatter grid presents several challenges. Therefore, the use of postacquisition software-based scatter reduction algorithms seems well justified, requiring a comprehensive evaluation of x-ray scatter content in the tomosynthesis projections. This study aims to gain insight into the behavior of x-ray scatter in tomosynthesis by characterizing the scatter point spread functions (PSFs) and the scatter to primary ratio (SPR) maps found in tomosynthesis of the breast. This characterization was performed using Monte Carlo simulations, based on the Geant4 toolkit, that simulate the conditions present in a digital tomosynthesis system, including the simulation of the compressed breast in both the cranio-caudal (CC) and the medio-lateral oblique (MLO) views. The variation of the scatter PSF with varying tomosynthesis projection angle, as well as the effects of varying breast glandular fraction and x-ray spectrum, was analyzed. The behavior of the SPR for different projection angle, breast size, thickness, glandular fraction, and x-ray spectrum was also analyzed, and computer fit equations for the magnitude of the SPR at the center of mass for both the CC and the MLO views were found. Within mammographic energies, the x-ray spectrum was found to have no appreciable effect on the scatter PSF and on the SPR. Glandular fraction and compressed breast size were found to have a small effect, while compressed breast thickness and projection angle, as expected, introduced large variations in both the scatter PSF and SPR. The presence of the breast support plate and the detector cover plate in the simulations introduced important effects on the SPR, which are also relevant to the scatter content in planar mammography.

BI-RADS decoded: detailed guidance on potentially confusing issues.

The American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) is the product of the initial collaboration between various committees of the ACR and several other organizations, such as the American College of American Pathologists and the American College of Surgeons. The impetus to establish a standardized method of reporting and follow-up began as early as 1985 when several of our clinical colleagues made a plea to the ACR to improve the reporting of mammograms. Reports were ambiguous and difficult to interpret, often leaving the clinician without a clear-cut management scenario. Over the years of increasing BI-RADS usage, the BI-RADS committee of the ACR received questions which, when analyzed, focused on specific areas of BI-RADS. A review of these problematic areas, with appropriate guidance, will be presented along with an introduction to the new US and MR imaging lexicons focusing on unique descriptors.