Mammographic Compression Research Articles

Threshold in breast compression reduction for full-field digital mammography and digital breast tomosynthesis

IntroductionBreast compression is essential in mammography to improve image quality and reduce radiation dose. However, it can cause discomfort or even pain in women which could discourage them from attending future mammography examinations. Therefore, this study aims to explore the maximum reduction in breast compression in full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) that is achievable without impacting on image quality and dose. MethodsTen compression force (CF) levels (20N–110N, with 10N intervals) were assessed on Siemens MAMMOMAT Inspiration with Nuclear Associates 18–228 phantom. Imaging was carried out in craniocaudal projection using Automatic Exposure Control at 28 kVp with a Tungsten/Rhodium anode/filter combination, and at 50° sweep angle for DBT. Using ImageJ software, image quality of the acquired mammograms and central tomosynthesis slices were examined based on mass conspicuity (MC) and microcalcification conspicuity (MicroC). Entrance skin dose (ESD) and mean glandular dose (MGD) were recorded from Digital Imaging and Communication in Medicine image header. Linear regression was performed to examine the relationship between CF with ESD, MGD, MC and MicroC. Differences in image quality and radiation dose were assessed with one-way analysis of variance and Kruskal-Wallis H test. ResultsSignificant correlations were noted between CF with ESD and MicroC for FFDM and DBT, with DBT also demonstrating associations with MGD and MC. No significant differences were observed for ESD, MGD, MC and MicroC when CF was reduced to 40N and 80N in FFDM and DBT respectively. ConclusionThis study demonstrated that CF can be reduced as low as 40N and 80N in FFDM and DBT respectively, without significant impact on image quality and radiation dose. Implications for practiceReduced mammographic compression may reduce discomfort or pain in women, which may improve attendance rate in breast screening programmes. Findings from this study will provide reference for future work examining breast compression in mammography.

Are mammography image acquisition factors, compression pressure and paddle tilt, associated with breast cancer detection in screening?

To assess the associations between objectively measured mammographic compression pressure and paddle tilt and breast cancer (BC) detected at the same ("contemporaneous") screen, subsequent screens, or in-between screens (interval cancers). Automated pressure and paddle tilt estimates were derived for 80,495 mammographic examinations in a UK population-based screening programme. Adjusted logistic regression models were fitted to estimate the associations of compression parameters with BC detected at contemporaneous screen (777 cases).Nested case-control designs were used to estimate associations of pressure and tilt with: (a) interval cancer (148 cases/625 age-matched controls) and (b) subsequent screen-detected cancer (344/1436), via conditional logistic regression. Compression pressure was negatively associated with odds of BC at contemporaneous screen (odds ratio (OR) for top versus bottom third of the pressure distribution: 0.74; 95% CI 0.60, 0.92; P-for-linear-trend (Pt) = 0.007). There was weak evidence that moderate pressure at screening was associated with lower odds of interval cancer (OR for middle versus bottom third: 0.63; 95% CI 0.38, 1.05; p = 0.079), but no association was found between pressure and the odds of BC at subsequent screen. There was no evidence that paddle tilt was associated with the odds of contemporaneous, subsequent screen or interval cancer detection. Findings are consistent with compression pressure, but not paddle tilt, affecting the performance of mammographic screening by interfering with its ability to detect cancers. Inadequate or excessive compression pressure at screening may contribute to a reduced ability to detect cancers, resulting in a greater number of interval cancer cases.

Using Breast Tissue Information and Subject-Specific Finite-Element Models to Optimize Breast Compression Parameters for Digital Mammography

Digital mammography has become a first-line diagnostic tool for clinical breast cancer screening due to its high sensitivity and specificity. Mammographic compression force is closely associated with image quality and patient comfort. Therefore, optimizing breast compression parameters is essential. Subjects were recruited for digital mammography and breast magnetic resonance imaging (MRI) within a month. Breast MRI images were used to calculate breast volume and volumetric breast density (VBD) and construct finite element models. Finite element analysis was performed to simulate breast compression. Simulated compressed breast thickness (CBT) was compared with clinical CBT and the relationships between compression force, CBT, breast volume, and VBD were established. Simulated CBT had a good linear correlation with the clinical CBT (R2 = 0.9433) at the clinical compression force. At 10, 12, 14, and 16 daN, the mean simulated CBT of the breast models was 5.67, 5.13, 4.66, and 4.26 cm, respectively. Simulated CBT was positively correlated with breast volume (r > 0.868) and negatively correlated with VBD (r < –0.338). The results of this study provides a subject-specific and evidence-based suggestion of mammographic compression force for radiographers considering image quality and patient comfort.

Finite element model of mechanical imaging of the breast.

Purpose: Malignant breast lesions can be distinguished from benign lesions by their mechanical properties. This has been utilized for mechanical imaging in which the stress distribution over the breast is measured. Mechanical imaging has shown the ability to identify benign or normal cases and to reduce the number of false positives from mammography screening. Our aim was to develop a model of mechanical imaging acquisition for simulation purposes. To that end, we simulated mammographic compression of a computer model of breast anatomy and lesions. Approach: The breast compression was modeled using the finite element method. Two finite element breast models of different sizes were used and solved using linear elastic material properties in open-source virtual clinical trial (VCT) software. A spherical lesion (15mm in diameter) was inserted into the breasts, and both the location and stiffness of the lesion were varied extensively. The average stress over the breast and the average stress at the lesion location, as well as the relative mean pressure over lesion area (RMPA), were calculated. Results: The average stress varied 6.2-6.5 kPa over the breast surface and 7.8-11.4 kPa over the lesion, for different lesion locations and stiffnesses. These stresses correspond to an RMPA of 0.80 to 1.46. The average stress was 20% to 50% higher at the lesion location compared with the average stress over the entire breast surface. Conclusions: The average stress over the breast and the lesion location corresponded well to clinical measurements. The proposed model can be used in VCTs for evaluation and optimization of mechanical imaging screening strategies.

Comparative Study on MATLAB based JPEG Image Size Reduction Using Discrete Cosine Transform and Shearlet Transform for Mammogram Images with Potential Hospital Data Storage Applications

Aim: The aim of this study was to compare Discrete cosine transform and Shearlet transform for mammographic image compression and determine better transform among them. Materials and methods: Sample mammographic images were collected- DCT (30) and Shearlet (30) for compression. Compression ratio was calculated by comparing the original and compressed image size. The significance of the data were calculated using SPSS software. Result: There was a statistical significance between DCT and shearlet based compression ratio data (p=0.035) deviation independent sample t test). Conclusion: DCT based compression ratio was higher (2.41) than the shearlet transforms (0.73). Hence, proving to be a better compression transform than its counterpart (shearlet).

Mammographic compression practices of force- and pressure-standardisation protocol: A scoping review.

IntroductionAs an efficient, effective and moderately inexpensive modality, mammography has been implemented as a cancer screening tool and in diagnostic management. However, appropriate breast compression is necessary for optimal outcomes. Current key measures of compression force are subjective and variable, giving rise to the concept of a ‘personalised’ pressure‐standardisation protocol.MethodsA scoping review of the literature was performed using the Arksey and O’Malley framework to explore the existing force‐ and pressure‐standardisation protocols in clinical application. A comprehensive search strategy and standardised study selection and evaluation were completed. This synthesis of existing knowledge can lead to the implementation of mechanically standardised mammographic compression pressure as a feasible tailored approach to clinical practice. Four databases (PubMed, MEDLINE, Embase and Scopus) were searched from the databases’ inception to 13 December 2019 for relevant information, and eighteen articles were selected for analysis.ResultsIn addition to current protocol comparison, emerging key concepts include the reasoning behind standardisation, the benefits of improved diagnostic outcomes/decreased pain with negligible change in image quality and average glandular dose (AGD), and the recommendation of a 10kPa (approximate) pressure‐standardisation protocol. Research to date is largely based abroad (Netherlands), with a strong focus on screening practices. Consequently, several gaps in the current literature were identified as potential directions for future investigation.ConclusionsAs a suggested mammographic guideline, compression pressures of approximately 10kPa aid in image acquisition reproducibility both within and between women; pain levels decrease, with minimal variations to breast thickness, AGD and image quality.

Detection of circulating tumor cells and circulating tumor DNA before and after mammographic breast compression in a cohort of breast cancer patients scheduled for neoadjuvant treatment

PurposeIt is not known if mammographic breast compression of a primary tumor causes shedding of tumor cells into the circulatory system. Little is known about how the detection of circulating biomarkers such as circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) is affected by breast compression intervention.MethodsCTCs and ctDNA were analyzed in blood samples collected before and after breast compression in 31 patients with primary breast cancer scheduled for neoadjuvant therapy. All patients had a central venous access to allow administration of intravenous neoadjuvant chemotherapy, which enabled blood collection from superior vena cava, draining the breasts, in addition to sampling from a peripheral vein.ResultsCTC and ctDNA positivity was seen in 26% and 65% of the patients, respectively. There was a significant increase of ctDNA after breast compression in central blood (p = 0.01), not observed in peripheral testing. No increase related with breast compression was observed for CTC. ctDNA positivity was associated with older age (p = 0.05), and ctDNA increase after breast compression was associated with high Ki67 proliferating tumors (p = 0.04). CTCs were more abundant in central compared to peripheral blood samples (p = 0.04).ConclusionsThere was no significant release of CTCs after mammographic breast compression but more CTCs were present in central compared to peripheral blood. No significant difference between central and peripheral levels of ctDNA was observed. The small average increase in ctDNA after breast compression is unlikely to be clinically relevant. The results give support for mammography as a safe procedure from the point of view of CTC and ctDNA shedding to the blood circulation. The results may have implications for the standardization of sampling procedures for circulating tumor markers.

Clinical validation of a pressure-standardized compression mammography system

ObjectivesValidation of a pressure-standardized compression mammography (PSCM) system, which aims to reduce discomfort and pain by applying the same pressure to every breast, independent of breast size. MethodsWe retrospectively studied mammograms of 39 patients acquired with a conventional force-standardized compression mammography (FSCM) technique and intra-individually compared them to mammograms acquired on a checkup visit with PSCM technique. Patients received one craniocaudal (CC) and one mediolateral oblique (MLO) compression for both breasts. All images were processed to obtain the contact area between the breast and the compression paddle. The pressure was calculated by dividing the compression force by the contact area. ResultsA total of 150 FSCM and 150 PSCM images were analyzed. The mean pressure decreased significantly from 17.1 to 12.8 kPa (p < 0.001), when using PSCM instead of FSCM. The applied pressure hardly depended on the breast contact area with the paddle (-0.014 kPa/cm2), while a clear dependency was observed using FSCM. Furthermore, the relative number of over-compressions reduced from 26% to 2%, benefitting patients with smaller breasts. ConclusionsOur study suggests that using PSCM can reduce patient discomfort and pain during mammographic compression compared to conventional FSCM as a result of lower average pressure. Moreover, standardized pressure may provide a more constant image quality, which could improve diagnostic performance.

Preliminary Clinical Experience with a Combined Automated Breast Ultrasound and Digital Breast Tomosynthesis System

We analyzed the performance of a mammographically configured, automated breast ultrasound (McABUS) scanner combined with a digital breast tomosynthesis (DBT) system. The GE Invenia ultrasound system was modified for integration with GE DBT systems. Ultrasound and DBT imaging were performed in the same mammographic compression. Our small preliminary study included 13 cases, six of whom had contained invasive cancers. From analysis of these cases, current limitations and corresponding potential improvements of the system were determined. A registration analysis was performed to compare the ease of McABUS to DBT registration for this system with that of two systems designed previously. It was observed that in comparison to data from an earlier study, the McABUS-to-DBT registration alignment errors for both this system and a previously built combined system were smaller than those for a previously built standalone McABUS system.

Towards an in-plane methodology to track breast lesions using mammograms and patient-specific finite-element simulations

In breast cancer screening or diagnosis, it is usual to combine different images in order to locate a lesion as accurately as possible. These images are generated using a single or several imaging techniques. As x-ray-based mammography is widely used, a breast lesion is located in the same plane of the image (mammogram), but tracking it across mammograms corresponding to different views is a challenging task for medical physicians. Accordingly, simulation tools and methodologies that use patient-specific numerical models can facilitate the task of fusing information from different images. Additionally, these tools need to be as straightforward as possible to facilitate their translation to the clinical area.This paper presents a patient-specific, finite-element-based and semi-automated simulation methodology to track breast lesions across mammograms. A realistic three-dimensional computer model of a patient’s breast was generated from magnetic resonance imaging to simulate mammographic compressions in cranio-caudal (CC, head-to-toe) and medio-lateral oblique (MLO, shoulder-to-opposite hip) directions. For each compression being simulated, a virtual mammogram was obtained and posteriorly superimposed to the corresponding real mammogram, by sharing the nipple as a common feature. Two-dimensional rigid-body transformations were applied, and the error distance measured between the centroids of the tumors previously located on each image was 3.84 mm and 2.41 mm for CC and MLO compression, respectively. Considering that the scope of this work is to conceive a methodology translatable to clinical practice, the results indicate that it could be helpful in supporting the tracking of breast lesions.

Technical Note: Validation of two methods to determine contact area between breast and compression paddle in mammography.

To assess the accuracy of two methods of determining the contact area between the compression paddle and the breast in mammography. An accurate method to determine the contact area is essential to accurately calculate the average compression pressure applied by the paddle. For a set of 300 breast compressions, we measured the contact areas between breast and paddle, both capacitively using a transparent foil with indium-tin-oxide (ITO) coating attached to the paddle, and retrospectively from the obtained mammograms using image processing software (Volpara Enterprise, algorithm version 1.5.2). A gold standard was obtained from video images of the compressed breast. During each compression, the breast was illuminated from the sides in order to create a dark shadow on the video image where the breast was in contact with the compression paddle. We manually segmented the shadows captured at the time of x-ray exposure and measured their areas. We found a strong correlation between the manual segmentations and the capacitive measurements [r = 0.989, 95% CI (0.987, 0.992)] and between the manual segmentations and the image processing software [r = 0.978, 95% CI (0.972, 0.982)]. Bland-Altman analysis showed a bias of -0.0038 dm2 for the capacitive measurement (SD 0.0658, 95% limits of agreement [-0.1329, 0.1252]) and -0.0035 dm2 for the image processing software [SD 0.0962, 95% limits of agreement (-0.1921, 0.1850)]. The size of the contact area between the paddle and the breast can be determined accurately and precisely, both in real-time using the capacitive method, and retrospectively using image processing software. This result is beneficial for scientific research, data analysis and quality control systems that depend on one of these two methods for determining the average pressure on the breast during mammographic compression.

Multimodal breast cancer imaging using coregistered dynamic diffuse optical tomography and digital breast tomosynthesis.

Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detector cover, respectively. We demonstrate system performance using static and dynamic tissue-like phantoms as well as in vivo images acquired from the pool of patients recalled for breast biopsies at the Massachusetts General Hospital Breast Imaging Division.

Mammographic compression in Asian women.

ObjectivesTo investigate: (1) the variability of mammographic compression parameters amongst Asian women; and (2) the effects of reducing compression force on image quality and mean glandular dose (MGD) in Asian women based on phantom study.MethodsWe retrospectively collected 15818 raw digital mammograms from 3772 Asian women aged 35–80 years who underwent screening or diagnostic mammography between Jan 2012 and Dec 2014 at our center. The mammograms were processed using a volumetric breast density (VBD) measurement software (Volpara) to assess compression force, compression pressure, compressed breast thickness (CBT), breast volume, VBD and MGD against breast contact area. The effects of reducing compression force on image quality and MGD were also evaluated based on measurement obtained from 105 Asian women, as well as using the RMI156 Mammographic Accreditation Phantom and polymethyl methacrylate (PMMA) slabs.ResultsCompression force, compression pressure, CBT, breast volume, VBD and MGD correlated significantly with breast contact area (p<0.0001). Compression parameters including compression force, compression pressure, CBT and breast contact area were widely variable between [relative standard deviation (RSD)≥21.0%] and within (p<0.0001) Asian women. The median compression force should be about 8.1 daN compared to the current 12.0 daN. Decreasing compression force from 12.0 daN to 9.0 daN increased CBT by 3.3±1.4 mm, MGD by 6.2–11.0%, and caused no significant effects on image quality (p>0.05).ConclusionsForce-standardized protocol led to widely variable compression parameters in Asian women. Based on phantom study, it is feasible to reduce compression force up to 32.5% with minimal effects on image quality and MGD.

Normalization of compression-induced hemodynamics in patients responding to neoadjuvant chemotherapy monitored by dynamic tomographic optical breast imaging (DTOBI).

We characterize novel breast cancer imaging biomarkers for monitoring neoadjuvant chemotherapy (NACT) and predicting outcome. Specifically, we recruited 30 patients for a pilot study in which NACT patients were imaged using dynamic tomographic optical breast imaging (DTOBI) to quantify the hemodynamic changes due to partial mammographic compression. DTOBI scans were obtained pre-treatment (referred to as day 0), as well as 7 and 30 days into therapy on female patients undergoing NACT. We present data for the 13 patients who participated in both day 0 and 7 measurements and had evaluable data, of which 7 also returned for day 30 measurements. We acquired optical images over 2 minutes following 4-8 lbs (18-36 N) of compression. The timecourses of tissue-volume averaged total hemoglobin (HbT), as well as hemoglobin oxygen saturation (SO2) in the tumor vs. surrounding tissues were compared. Outcome prediction metrics based on the differential behavior in tumor vs. normal areas for responders (>50% reduction in maximum diameter) vs. non-responders were analyzed for statistical significance. At baseline, all patients exhibit an initial decrease followed by delayed recovery in HbT, and SO2 in the tumor area, in contrast to almost immediate recovery in surrounding tissue. At day 7 and 30, this contrast is maintained in non-responders; however, in responders, the contrast in hemodynamic time-courses between tumor and normal tissue starts decreasing at day 7 and substantially disappears at day 30. At day 30 into NACT, responding tumors demonstrate "normalization" of compression induced hemodynamics vs. surrounding normal tissue whereas non-responding tumors did not. This data suggests that DTOBI imaging biomarkers, which are governed by the interplay between tissue biomechanics and oxygen metabolism, may be suitable for guiding NACT by offering early predictions of treatment outcome.

Abstract P4-03-04: Dynamic tomographic optical breast imaging (TOBI) for neoadjuvant chemotherapy monitoring

Abstract Background: Dynamic Diffuse optical imaging using near-infrared light was shown to be promising method for neoadjuvant therapy monitoring as an alternative functional imaging that is low-cost, non-invasive, portable, safe and simple to operate. While optical breast imaging methods rely on "static" assessments of tissue oxy- and deoxy- hemoglobin concentration without contrast agents, they are insufficient for clinical applications. Dynamic tomographic optical imaging induces tumor-sensitive hemodynamic variations, as a contrast mechanism, driven by fractional mammographic compression. These tumor contrast measurements are governed by interlay of tissue biomechanics and oxygen metabolism. In this study we seek to evaluate the predictive value of these biomarkers with respect to treatment outcome. Methods: A group of 22 patients with locally advanced breast cancer were scanned using our dynamic TOBI system before and during neoadjuvant chemotherapy. In this analysis we focused on pre-treatment, day 7 and day 30 post-treatment dynamic TOBI scans. Both breasts are compressed in turn to 4-8 lbs of force (depending on size) and optical images are acquired every 2 seconds over 2 minutes. We calculate the time course of oxy (HbO), deoxy (HbR)and total (HbT) hemoglobin concentration as well as the hemoglobin oxygen saturation (SO2). Regions of interest are defined in the optical images to correspond to the radiology identified tumor location, and the healthy tissue in the same breast, respectively. We compare the time courses in the two regions at baseline, day 7 and 30 days after initiation of treatment. Results: In this analysis we present results from 10 patients including 6 responders (defined as greater than 50% reduction in the largest tumor axis from baseline imaging and final pathology) and 4 non-responders. As the compression plates are held in place the tissue collagen matrix begins to stretch, effectively reducing the compression force. At baseline, all patients exhibit a decrease followed by delayed recovery in HbT, and SO2 in the tumor area, in contrast to immediate recovery in surrounding tissue. At day 7 and 30, this contrast is maintained in non-responders (&amp;lt;50% reduction in tumor maximum diameter); however, in responders, the contrast starts decreasing at day 7 and substantially disappears at day 30. Average changes in HbT and SO2, show that the contrast between normal and tumor increases somewhat at day 7 and more noticeably at day 30 in non-responders to NACT. Comparing hemodynamic changes in responders and non-responders, it is clear that at three selected time points (30, 60 and 90 s) during the scan, the contrast between tumor and normal tissue in both ΔHbT and ΔSO2 is reduced for the responders at day 7 and day 30. Conclusions: These initial results suggest that dynamic optical breast imaging can detect changes due to treatment and have predictive value for the treatment outcome. DTOBI can show the difference in hemodynamic response to compression between tumor and normal tissue and demonstrates the feasibility of using dynamic optical breast tomography for neoadjuvant chemotherapy monitoring. ongoing. Citation Format: Sajjadi AY, Singh B, Deng B, Boas DA, Moy B, Schapira L, Bardia A, Specht MC, Carp SA, Isakoff SJ. Dynamic tomographic optical breast imaging (TOBI) for neoadjuvant chemotherapy monitoring. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-03-04.

Force balancing in mammographic compression.

In mammography, the height of the image receptor is adjusted to the patient before compressing the breast. An inadequate height setting can result in an imbalance between the forces applied by the image receptor and the paddle, causing the clamped breast to be pushed up or down relative to the body during compression. This leads to unnecessary stretching of the skin and other tissues around the breast, which can make the imaging procedure more painful for the patient. The goal of this study was to implement a method to measure and minimize the force imbalance, and to assess its feasibility as an objective and reproducible method of setting the image receptor height. A trial was conducted consisting of 13 craniocaudal mammographic compressions on a silicone breast phantom, each with the image receptor positioned at a different height. The image receptor height was varied over a range of 12 cm. In each compression, the force exerted by the compression paddle was increased up to 140 N in steps of 10 N. In addition to the paddle force, the authors measured the force exerted by the image receptor and the reaction force exerted on the patient body by the ground. The trial was repeated 8 times, with the phantom remounted at a slightly different orientation and position between the trials. For a given paddle force, the obtained results showed that there is always exactly one image receptor height that leads to a balance of the forces on the breast. For the breast phantom, deviating from this specific height increased the force imbalance by 9.4 ± 1.9 N/cm (6.7%) for 140 N paddle force, and by 7.1 ± 1.6 N/cm (17.8%) for 40 N paddle force. The results also show that in situations where the force exerted by the image receptor is not measured, the craniocaudal force imbalance can still be determined by positioning the patient on a weighing scale and observing the changes in displayed weight during the procedure. In mammographic breast compression, even small changes in the image receptor height can lead to a severe imbalance of the applied forces. This may make the procedure more painful than necessary and, in case the image receptor is set too low, may lead to image quality issues and increased radiation dose due to undercompression. In practice, these effects can be reduced by monitoring the force imbalance and actively adjusting the position of the image receptor throughout the compression.

Pain-preventing strategies in mammography: an observational study of simultaneously recorded pain and breast mechanics throughout the entire breast compression cycle.

BackgroundMany women consider mammography painful. Existing studies on pain-preventing strategies only mention pain scores reported before and after breast compression. Studying the pain dynamics during the entire compression cycle may provide new insights for effective pain-preventing strategies.MethodsThis observational study included 117 women who consented to use a custom turning knob to indicate their pain experience during standard mammographic breast compressions in the Academic Medical Center in Amsterdam, The Netherlands. The breast thickness, compression force, contact area, contact pressure and pain experience were recorded continuously. Breast volume was calculated retrospectively from the mammograms. We visualized the progression of pain in relation to breast mechanics for five groups of breast volumes and we performed multivariable regressions to identify factors that significantly predict pain experience.ResultsBreast compressions consisted of a deformation phase for flattening, and a clamping phase for immobilization. The clamping phase lasted 12.8 ± 3.6 seconds (average ± standard deviation), 1.7 times longer than the 7.5 ± 2.6 seconds deformation phase. During the clamping phase, the average pain score increased from 4.75 to 5.88 (+24%) on a 0 – 10 Numerical Rating Scale (NRS), and the proportion of women who reached severe pain (NRS ≥ 7) increased from 23% to 50% (more than doubled). Moderate pain (NRS ≥ 4) was reported up to four days after the mammogram. Multivariable analysis showed that pain recollection of the previous mammogram and breast pain before the compression, are significant predictors for pain. Women with smallest breasts experienced most pain: They received highest contact pressures (force divided by contact area) and the pressure increased at the highest rate.ConclusionWe suggest further research on two pain-preventing strategies: 1) using a personalized compression protocol by applying to all breasts the same target pressure at the same, slow rate, and 2) shortening the phase during which the breast is clamped.

Mammographic compression – A need for mechanical standardization

BackgroundA lack of consistent guidelines regarding mammographic compression has led to wide variation in its technical execution. Breast compression is accomplished by means of a compression paddle, resulting in a certain contact area between the paddle and the breast. This procedure is associated with varying levels of discomfort or pain. On current mammography systems, the only mechanical parameter available in estimating the degree of compression is the physical entity of force (daN). Recently, researchers have suggested that pressure (kPa), resulting from a specific force divided by contact area on a breast, might be a more appropriate parameter for standardization. Software has now become available which enables device-independent cross-comparisons of key mammographic metrics, such as applied compression pressure (force divided by contact area), breast density and radiation dose, between patient populations. PurposeTo compare the current compression practice in mammography between different imaging sites in the Netherlands and the United States from a mechanical point of view, and to investigate whether the compression protocols in these countries can be improved by standardization of pressure (kPa) as an objective mechanical parameter. Materials and methodsWe retrospectively studied the available parameters of a set of 37,518 mammographic compressions (9188 women) from the Dutch national breast cancer screening programme (NL data set) and of another set of 7171 compressions (1851 women) from a breast imaging centre in Pittsburgh, PA (US data set). Both sets were processed using VolparaAnalytics and VolparaDensity to obtain the applied average force, pressure, breast thickness, breast volume, breast density and average glandular dose (AGD) as a function of the size of the contact area between the breast and the paddle. ResultsOn average, the forces and pressures applied in the NL data set were significantly higher than in the US data set. The relative standard deviation was larger in the US data set than in the NL data set. Breasts were compressed with a force in the high range of >15daN for 31.1% and >20kPa for 12.3% of the NL data set versus, respectively, 1.5% and 1.7% of the US data set. In the low range we encountered compressions with a pressure of <5daN for 21.1% and <5kPa for 21.7% of the US data set versus, respectively, 0.05% and 0.6% in the NL data set. Both the average and the standard deviation of the AGD were higher in the US data set. Conclusion(1) Current mammographic breast compression policies lead to a wide range of applied forces and pressures, with large variations both within and between clinical sites. (2) Pressure standardization could decrease variation, improve reproducibility, and reduce the risk of unnecessary pain, unnecessary high radiation doses and inadequate image quality.

PB.22. Does mammographic compression force at breast screening influence the likelihood of subsequent screening attendance?

Previous work has demonstrated that approximately 14% of women who attend their first breast screening appointment fail to attend the next appointment. It is well recognised that some women experience marked discomfort or pain during mammography which may be related to the breast compression force applied. This study investigates whether applied compression force is related to the likelihood of attendance for the next scheduled screening mammogram.

Image fusion of Ultrasound Computer Tomography volumes with X-ray mammograms using a biomechanical model based 2D/3D registration

Ultrasound Computer Tomography (USCT) is a promising breast imaging modality under development. Comparison to a standard method like mammography is essential for further development. Due to significant differences in image dimensionality and compression state of the breast, correlating USCT images and X-ray mammograms is challenging. In this paper we present a 2D/3D registration method to improve the spatial correspondence and allow direct comparison of the images. It is based on biomechanical modeling of the breast and simulation of the mammographic compression. We investigate the effect of including patient-specific material parameters estimated automatically from USCT images. The method was systematically evaluated using numerical phantoms and in-vivo data. The average registration accuracy using the automated registration was 11.9mm. Based on the registered images a method for analysis of the diagnostic value of the USCT images was developed and initially applied to analyze sound speed and attenuation images based on X-ray mammograms as ground truth. Combining sound speed and attenuation allows differentiating lesions from surrounding tissue. Overlaying this information on mammograms, combines quantitative and morphological information for multimodal diagnosis.