Craniocaudal Mammograms Research Articles

Influence of Using Manual or Automatic Breast Density Information in a Mass Detection CAD System

The goal of this article is to analyze and compare the performance of a developed mass computer-aided detection (CAD) system that takes breast density information into account when using manual or automatic breast density annotations in the training step. The advantages of considering this breast density information will be highlighted. The image database used in this article is 92 mediolateral oblique (MLO) and 92 craniocaudal (CC) mammograms obtained by a full-field digital mammographic unit. All mammograms contain at least one mass. The evaluation of the experiments is performed using free receiver operating characteristic analysis for evaluating the detection performance and pixel-based receiver operating characteristic analysis for evaluating the segmentation accuracy. In addition, the performance of the automatic breast density classifier is shown using confusion matrices. When the breast density information is not considered and at a specificity of two false positives per image, the sensitivity obtained by the CAD system is 0.747 for the CC views and 0.853 for the MLO views. Considering the breast density information, the sensitivity for CC and MLO mammograms increases to 0.800 and 0.893, respectively, using manual classification, and 0.827 and 0.907, respectively, using automatic estimation. The same trend is observed when evaluating the CAD segmentation accuracy for detected masses in terms of area under the curve values: without considering breast density, these are 0.920 +/- 0.057 and 0.917 +/- 0.072; using manual classification, 0.934 +/- 0.039 and 0.932 +/- 0.046; and using automatic estimation, 0.947 +/- 0.038 and 0.946 +/- 0.045 for CC and MLO views, respectively. The experiments showed improved results when breast density information was taken into account. Moreover, the results obtained when using automatic breast density estimation outperformed those based on the manual annotations provided by expert radiologists. In this sense, the experiments showed that breast density information can be beneficial for CAD systems, and this information can be estimated robustly by an automatic procedure, which reduces the inter- and intra-class variability of the radiologists.

Abstract 3768: Comparison of breast density measured by dual energy x-ray Absorptiometry (DXA) with mammographic density among adult women

Abstract Mammographic density, the distribution of fat, connective, and epithelial tissues in the female breast, is strongly associated with breast cancer and has been used as a biomarker for breast cancer risk among adult women. While use of mammography is limited due to concerns about radiation exposure, Dual Energy X-ray Absorptiometry (DXA), commonly available in medical care settings, has very low radiation. In this analysis, we compared breast density measured by DXA with mammographic density among adult women. We recruited 101 participants aged 30 years and older with a normal mammogram (defined as BIRADS categories 1 through 3) through Kaiser Permanente Hawaii. After completing a questionnaire asking for demographic, reproductive, anthropometric, and medical information, all women received DXA scans of both breasts, as well as of the whole body, using a GE Lunar Prodigy Bone Densitometer. On the DXA scans, the breast image was manually outlined and the following measures were computed: percent fibroglandular volume density (% FGV), absolute fibroglandular volume, total breast area, and volume. After digitizing the most recent craniocaudal (CC) and mediolateral (ML) mammograms, total breast area, dense area, and percent density were estimated using a computer-assisted method (Cumulus). For the overall population, mean % FGV was 38.8±14.3%, and mean percent density was 31.9±18.2% for CC views and 28.3±16.2% for ML views. Both DXA and mammographic measures showed high correlations between left and right breasts ranging from 0.85 to 0.98 (p <0.0001). When comparing DXA and mammographic measures, the correlation coefficients between % FGV and percent density were 0.76 for both CC and ML views (p <0.0001). Associations with common risk factors showed similar patterns for DXA and mammographic densities; in particular, the inverse associations with BMI and age at menarche were evident for both methods. Multilinear regression with stepwise selection indicated an explained variance of 0.57 for % FGV alone and 0.58 for % FGV plus parity. The current comparison suggests that DXA has the potential to provide a low-radiation option to evaluate breast density for women who do not undergo mammography. This may allow improved individualized risk assessment to identify women for targeted prevention strategies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3768.

Mammographic Determination of Breast Volume by Elliptical Cone Estimation

We propose a new breast volume calculation method, treating the breast as an elliptical cone on craniocaudal and medial-lateral-oblique mammograms. This study aims to compare the accuracy and reproducibility of this proposed calculation method to the old Katariya method, which calculates breast volume as a circular cone on the craniocaudal mammogram only. From January 2005 to December 2006, 83 mastectomy patients with recorded breast weight and available preoperative mammographic films were included in the present study. Two surgeons independently measured breast height and width on the preoperative craniocaudal and medial-lateral-oblique mammograms. Breast volume was calculated as a circular cone in the craniocaudal view, and as an elliptical cone in both the craniocaudal and the medial-lateral-oblique mammograms. The accuracy of each method was determined and compared by linear regression analyses. Interobserver variability was assessed by bivariate correlation. The most accurate formula for calculating breast volume was the one that assumed the elliptical cone projection. The mean error of estimated breast volume using the elliptical cone (EC) formula is 3.8 cm(3) (standard deviation [SD] = 133 cm(3)). The mean error of traditional circular cone (CC) formula is -51.3 cm(3) (SD = 182 cm(3)). From a linear regression model, the correlation coefficient of estimated breast volume using EC formula measured 0.977, whereas that using the CC formula measured 0.952 (Fig. 1). Measurements were reproducible between the two independent observers; the Pearson correlation for the EC formula is 0.93 (p < 0.001), and that for the CC formula is 0.95 (p < 0.001). Breast volume can be accurately determined from measurements made on mammograms. The proposed EC formula calculating breast volume on both the craniocaudal and the medial-lateral-oblique mammograms may be more accurate, as the horizontal and vertical dimensions of the breast are not always the same. In addition, height measurement on the medial-lateral-oblique film can eliminate the compression error as the craniocaudal film may miss the base of the breast and underestimate the breast volume. Taking both mammogram views for measurement is comparably reproducible to the traditional method. Reproducibility of measurement can be further enhanced by better defining the point of measurements.

Mammographic CAD: Correlation of regions in ipsilateral views - a pilot study

Background: Radiologists analyse both standard mammographic views of a breast to confirm the presence of abnormalities and reduce false-positives. However, at present no computer-aided diagnosis system uses ipsilateral mammograms to confirm the presence of suspicious features. &#x0D; Aim: The aim of this study was to develop image-processing algorithms that can be used to match a suspicious feature from one mammographic view to the same feature in another mammographic view of the same breast. This algorithm can be incorporated into a computer-aided diagnosis package to confirm the presence of suspicious features.&#x0D; Method: The algorithms were applied to 68 matched pairs of cranio-caudal and mediolateral-oblique mammograms. The results of this pilot study take the form of maps of similarity. A novel method of evaluating the similarity maps is presented, using the area under the receiver operating characteristic curve (AUC) and the contrast (C) between the area of the matched region and the background of the similarity map. &#x0D; Results and Conclusions: The first matching algorithm (using texture measures extracted from a grey-level co-occurrence matrix (GLCM) and a Euclidean distance similarity metric) achieved an average AUC=0.80±0.17 with an average C=0.46±0.26. The second algorithm (using GLCMs and a mutual information similarity metric) achieved an average AUC=0.77±0.25 with an average C=0.50±0.42. The latter algorithm also performed remarkably well with the matching of malignant masses and achieved an average AUC=0.96±0.05 with an average C=0.90±0.21.

Analysis of 107 breast lesions with automated 3D ultrasound and comparison with mammography and manual ultrasound

Objectives Our aim was to investigate the diagnostic potential of an automated ultrasound (US) breast scanner prototype and compare it with manual US and mammography. Methods Ninety-seven patients with a total of 107 breast lesions had mammograms, manual US and an automated breast US scan. Multiplanar reconstructions in coronal, axial and the sagittal view were reconstructed from the automated dataset and visualized. After biopsy, all lesions were confirmed histologically. The data were evaluated according to the BIRADS (Breast Imaging Reporting and Data System) classification. The sensitivity and specificity were analyzed. Results The BIRADS criterion “margin” was significantly related to the overall BIRADS classification, independently of the US method being used. The sensitivity of mammography was significantly lower than of each US method (Fisher's exact test with p < 0.05). There were no significant differences between the US methods. Conclusions The reconstructed third (axial) image plane of the whole breast, which corresponds to a craniocaudal mammogram, can give additional information about both, site and differential diagnosis of a lesion. Although image quality was sufficient, automated US is not good enough to replace manual US at this time.

Longitudinal Trends in Mammographic Percent Density and Breast Cancer Risk

Mammographic density is a strong risk factor for breast cancer. However, whether changes in mammographic density are associated with risk remains unclear. A study of 372 incident breast cancer cases and 713 matched controls was conducted within the Mayo Clinic mammography screening practice. Controls were matched on age, exam date, residence, menopause, interval between, and number of mammograms. All serial craniocaudal mammograms 10 years before ascertainment were digitized, and quantitative measures of percent density (PD) were estimated using a thresholding method. Data on potential confounders were abstracted from medical records. Logistic regression models with generalized estimating equations were used to evaluate the interactions among PD at earliest mammogram, time from earliest to each serial mammogram, and absolute change in PD between the earliest and subsequent mammograms. Analyses were done separately for PD measures from the ipsilateral and contralateral breast and also by use of hormone therapy (HT). Subjects had an average of five mammograms available, were primarily postmenopausal (83%), and averaged 61 years at the earliest mammogram. Mean PD at earliest mammogram was higher for cases (31%) than controls (27%; ipsilateral side). There was no evidence of an association between change in PD and breast cancer risk by time. Compared with no change, an overall reduction of 10% PD (lowest quartile of change) was associated with an odds ratio of 0.9997 and an increase of 6.5% PD (highest quartile of change) with an odds ratio of 1.002. The same results held within the group of 220 cases and 340 controls never using HT. Among the 124 cases and 337 controls known to use HT during the interval, there was a statistically significant interaction between change in PD and time since the earliest mammogram (P = 0.01). However, in all groups, the risk associated with the earliest PD remained a stronger predictor of risk than change in PD. We observed no association between change in PD with breast cancer risk among all women and those never using HT. However, the interaction between change in PD and time should be evaluated in other populations.

Patient dose in full-field digital mammography: an Italian survey.

The aim of this study was to compare performance and patient dose of full-field digital mammography units for clinical use. Measurements of linearity and automatic exposure control stability were performed on four units installed in as many Italian sites. The tube output was also obtained by the same ionization chamber, permitting to evaluate ratios mGy/mAs for each available spectrum. The entrance air-kerma was calculated over a sample of 800 cranio-caudal mammograms and the average glandular dose obtained, assuming two mean glandular compositions of 50 and 30%, respectively. Digital systems showed very good linearity and comparable responses. The stability of the automatic exposure control was better than 5% for all systems. Regarding doses, the two mammography units that work mainly in contrast mode deliver, respectively, 17 and 28% more dose compared with those working in standard mode. For the latter mode, the mean average glandular dose was in the range 1.25-1.37 mGy and 1.37-1.49 mGy for the 50 and 30% glandular composition, respectively. Results of this study were compared with those of other surveys, showing that full-field digital mammography allows a significant clinical dose reduction compared with screen/film mammography.

Dosimetric Evaluation of the Mean Glandular Dose for Mammography in Korean Women: A Preliminary Report

The purpose of this study was to evaluate the thickness of the compressed breast in mediolateral oblique (MLO) and craniocaudal (CC) mammograms, to relate these thickness and breast patterns to mean glandular dose (MGD) in Korean women, and to evaluate the suitability of using the American College of Radiology's Recommendations for Korean women from a quality assurance standpoint. The study population consisted of 92 paired MLO and CC mammograms obtained on one mammographic unit. The digital readouts of compressed breast thickness, applied compression force and tube voltage were recorded. Entrance skin exposure was measured by dosimetry. MGD was calculated by multiplying entrance skin exposure by the exposure-to-absorbed dose conversion factor. The range of breast thickness was 1.3-6.2 cm in CC mammograms with a mean breast thickness of 3.6 cm, and 1.6-6.5 cm in MLO mammograms with a mean breast thickness of 3.9 cm. MGDs in CC and MLO mammograms were 1.77 mSv and 1.88 mSv per view, respectively. Breast composition patterns were divided into 4 groups according to ACR BI-RADS; P1 (n=20), P2 (n=16), P3 (n=48) and P4 (n=8). The MGDs for these groups were: 1.82, 1.84, 1.84, and 1.91 mSv, respectively. When subjects were subdivided by breast thickness into three groups, namely, below 3 cm, 3 cm to 4.2 cm, aaa and above 4.2 cm, the corresponding MGDs were 1.83, 1.86, and 1.91 mSv. According to our initial trial, the mean breast thickness and the MGDs of Korean women are lower than recommended by the American College of Radiology, which are commonly used for quality assurance purposes.

Reasons for failure of a mammography unit at clinical image review in the American College of Radiology Mammography Accreditation Program.

To identify the most common deficiencies in the quality of mammograms submitted for clinical image evaluation (evaluation of image from actual patient referred for mammography). In 1997, the American College of Radiology Mammography Accreditation Program reviewed clinical images for 2,341 mammography units. For each mammography unit, the facility submitted bilateral mediolateral oblique and craniocaudal mammograms obtained in a woman with fatty breasts and a woman with dense breasts. Images were reviewed independently by two experienced radiologists. Reviewers listed the general categories and specific deficiencies that led to a decision to fail the unit that produced the clinical images. Of the 2,341 mammography units, 1,034 (44%) failed the clinical image evaluation process. Of 6,128 categories cited by reviewers as deficient, 1,250 (20%) involved problems in positioning; 944 (15%), exposure; 887 (14%), compression; 806 (13%), sharpness; 785 (13%), contrast; 703 (11%), labeling; 465 (8%), artifacts; and 288 (5%), noise. A significantly higher proportion of failures was attributed to positioning deficiencies for fatty breasts than for dense breasts (P =.028). Higher proportions of failures in dense breasts were related to compression (P <.001) and exposure (P <.001) deficiencies. Common problems in clinical image quality have been identified. This information should be useful for educators and facilities striving to improve the quality of mammography.

Analysis of optical density and contrast in mammograms.

The objective of this project is the development of tools for the UK NHSBSP to assess image quality quantitatively in clinical films, for the purposes of optimizing imaging procedures and audit. As an initial step, 120 mammograms of 46 women on a single day of screening were digitized and analysed to produce indices of optical density (OD) and contrast. Analysis was performed on three regions of interest (ROI): pectoral muscle, main breast and skin edge. Two radiologists independently graded the quality of information in the different parts of each mammogram, and categorized breast type as either "dense", "mixed density" or "fatty". Measurements of contrast and OD generally correlated well with the opinions of the radiologists. For the oblique mammograms, the mean OD in the main breast ranged between films from 1.25 to 2.24 with a mean of 1.69 +/- 0.02. In the craniocaudal mammograms, the mean OD in the main breast ROI ranged from 1.14 to 1.94 with a mean of 1.61 +/- 0.05. The OD for a quality control film of a 40 mm block of PMMA exposed on the same day with this system was 1.53. A contrast index (CI) was calculated for each mammogram as the difference between the points of maximum and minimum OD in the main breast. Mean CI was 1.02 +/- 0.09 for fatty breasts, 1.50 +/- 0.10 for mixed density breasts and 2.05 +/- 0.23 for dense breasts. A review of the radiologist assessments indicated that the main breast was satisfactorily displayed when glandular and fatty tissues were displayed within the OD range 0.8-2.9. An analysis of the dynamic range requirements showed that 17% of films had a dynamic range that lay above that calculated using the suggested OD limits.

Smoking and high-risk mammographic parenchymal patterns: a case-control study.

STATEMENT OF FINDINGS: Current smoking was strongly and inversely associated with high-risk patterns, after adjustment for concomitant risk factors. Relative to never smokers, current smokers were significantly less likely to have a high-risk pattern. Similar results were obtained when the analysis was confined to postmenopausal women. Past smoking was not related to the mammographic parenchymal patterns. The overall effect in postmenopausal women lost its significance when adjusted for other risk factors for P2/DY patterns that were found to be significant in the present study, although the results are still strongly suggestive. The present data indicate that adjustment for current smoking status is important when evaluating the relationship between mammographic parenchymal pattern and breast cancer risk. They also indicate that smoking is a prominent potential confounder when analyzing effects of other risk factors such as obesity-related variables. It appears that parenchymal patterns may act as an informative biomarker of the effect of cigarette smoking on breast cancer risk.

New Film-Cassette System to Obtain Wider Field of Craniocaudal View Compared with Conventional Technique in Screening Mammography

Purpose : To evaluate the efficacy of a newly designed cassette and film system used to obtain a craniocaudal(CC) image during mammographic examination. Materials and Methods : We designed a film-cassette system for use inobtaining a CC image. The merit of this system is that the contact plane between the film and film cassette andthe thoracic wall of the examinee changed from linear to concave, thus including more tissue on the image. Twentywomen examined by screening mammography underwent conventional and new CC plane examinations. The distance fromthe nipple to the posterior margin of the included breast tissue, as seen on CC mammograms, was measured using thetwo techniques, and the difference between the respective results was analyzed by paired t-test. Results : Thedistance from the nipple to the posterior margin was at the lateral portion of theconventional and new CC image, respectively. This distance was thus significantly greater on the new than on theconventional image (p

Estimation of compressed breast thickness during mammography.

To estimate radiation dose during mammography the breast thickness must be known. We present a new method for estimating the thickness of a compressed breast using only the breast image as projected onto a mammogram, calibration data such as the mAs value and image processing techniques. The method proves to be of high accuracy (+/- 0.2 cm for craniocaudal mammograms) and has the advantage over other methods of allowing retrospective estimation of thickness.

Breast thickness in routine mammograms: effect on image quality and radiation dose.

The purpose of this study was to compare the thickness of the compressed breast between mediolateral oblique and craniocaudal mammograms and to relate these differences in thickness to image quality and radiation dose. These differences may partially explain why some subtle tumors are better visualized on the craniocaudal view. The study population consisted of 250 paired mediolateral oblique and craniocaudal mammograms obtained on one mammographic unit by seven certified mammography technologists during a 2-month period. Only women with breast implants, prior lumpectomy and radiotherapy, or chest wall deformity were excluded. The digital readout of compressed breast thickness and applied compression force was recorded. Mammographic positioning was assessed using standard criteria. Absorbed radiation dose at different thicknesses was measured with a BR-12 breast phantom. Image quality differences for geometric unsharpness and contrast were calculated for the observed breast thickness differences between mediolateral oblique and craniocaudal mammograms. The mean thickness of the compressed breast on the craniocaudal view was less than the mean thickness on the mediolateral oblique view (4.4 versus 4.8 cm, p < .0001) despite the greater force used to compress the breast for mediolateral oblique than for craniocaudal views (93 versus 86 newtons, p < .0001). The breast thickness on the mediolateral oblique view exceeded that on the craniocaudal view in 98 (84%) of 117 pairs that differed in thickness by 5 mm or more and 46 (94%) of 49 pairs that differed by 10 mm or more (p < .0001). Geometric unsharpness increased by 8% and 19% when a 4.4-cm-thick breast was compared to a 4.8- and 5.4-cm-thick breast, respectively. A 5% and 12% loss of contrast was noted when a 4.4-cm-thick breast was compared to a 4.8- and 5.4-cm-thick breast. Mean glandular radiation dose at 4.4, 4.8, and 5.4 cm was 1.40, 1.70, and 2.33 mGy, respectively. The compressed breast is 8% thicker on mediolateral oblique than on craniocaudal mammograms, a small but statistically significant difference. This difference results in a small loss of spatial and contrast resolution on the mediolateral oblique views and an increase in radiation dose. These image quality differences may partially explain why some subtle carcinomas are better visualized on the craniocaudal view.

Mammographic positioning: evaluation from the view box.

To evaluate the quality of breast positioning for mediolateral oblique (MLO) and craniocaudal (CC) views, a prospective study of 1,000 consecutive bilateral screening mammographic examinations was performed. Six criteria were tested, including depth of tissue seen, inferior extent of the pectoral muscle relative to the posterior nipple line, presence of fibroglandular tissue at the posterior edge of the film, and whether the nipple was in profile. Pectoral muscle was depicted to within 1 cm of the nipple line or below it on 1,612 of the 2,000 MLO mammograms (81%); all fibroglandular tissue was depicted on 1,532 MLO mammograms (77%). The depth of tissue depicted on the CC mammogram was within 1 cm greater or less than the depth on the MLO mammogram on 1,586 CC mammograms (79%); the pectoral muscle was seen on 646 CC mammograms (32%). The nipple was in profile in 1,769 MLO mammograms (88%) and 1,783 CC mammograms (89%) but not in profile in either view in 83 cases (4%). Overall improvement was seen in 400 of 587 examinations (68%) when new mammograms were compared with previous mammograms. These criteria can be used to evaluate positioning performance and for quality control.

Carcinoma mimicked by the sternal insertion of the pectoral muscle.

A prospective study of 1843 patients was performed to identify the frequency of imaging the medial portion of the greater pectoral muscle on the craniocaudal projection during routine mammography. This artifact was seen in 14 patients. None of these patients had a palpable abnormality; additional craniocaudal views revealed continuity of the density with the pectoral muscle. Four patients were reexamined in 6 months; no change was seen in the size of the density. The density is thought to represent the medial portion of the pectoral muscle, which is included because of vigorous retraction of the breast and slight external rotation during positioning for the craniocaudal view. Familiarity with the appearance of the medial portion of the greater pectoral muscle on craniocaudal mammograms will help prevent inaccurate interpretations and unnecessary biopsies.

Preoperative computed-tomographic localization of breast calcifications.

A technique for computed-tomographic localization of deep breast calcifications which can be seen on mediolateral but not on craniocaudal mammograms is described.

CT scanning of the breast using a conventional CT scanner

Using a conventional body CT scanner, computed tomography of the breast was performed on 32 patients known to have or suspected of having breast masses. Xeromammograms were available for comparison in all cases. All mass lesions were histologically proved. Seven patients were examined prone, 25 supine. The prone position yielded pictures that resembled craniocaudal mammograms. Breast asymmetry, skin thickening, stranding from a mass to the chest wall, calcification, and axillary lymphadenopathy could be demonstrated by means of CT. The portion of the breast adjacent to the chest wall was more readily examined by means of CT than by conventional mammography. Internal mammary nodes could not be demonstrated.