X-ray Mammography Research Articles

Abstract ID: 189 Uncertainty estimation of MC simulated mammography spectra

Novel breast dosimetry applications require the knowledge of incident X-ray spectra, in mammography energy range [1] . Furthermore, the knowledge of the spectra transmitted through breast tissue is important in the phantom development context. A vast number of MC codes are used as models to generate diagnostic X-ray spectra; however, comparisons of those to experimentally measured X-ray spectra (validations) must be done to assure modelled spectra are representative of real X-ray beams. For these comparisons to be reliable, accurate uncertainty estimation of the counts in the spectra channels is required. This work’s objective was to accurately assess the uncertainties associated to the counts of incident and transmitted mammography MC modelled spectra. In this work, the PENELOPE MC code was used to simulate a CdTe spectrometer’s detection of mammography X-ray spectra, and the attenuation of these spectra after transmission through commercial breast phantoms. Four anode-filter combinations, three commercial breast phantoms and several attenuation thicknesses were used. Altogether, 108 spectra were simulated. The measured spectra emitted by each X-ray generators were used as the MC simulations input spectra, after escape and efficiency distortion effects were corrected by the stripping method. The uncertainty of the modelled spectra’s channels was estimated through MC uncertainty propagation method. For each condition, 25 simulations were performed, varying the input parameters (input spectra and phantom composition) according to their probability density functions. The simulated spectra validation was done through the assessment of the mean weighted squared residuals (MWSR). Except for model’s inaccuracies, good estimation of the uncertainties yields a MWSR equal to 1, which is this quantity’s expected value. The mean of the 108 calculated MWSRs yielded 3.76(03) when only Poisson’s uncertainty was used. Therefore, we conclude Poisson’s uncertainty underestimates the uncertainty of the spectra channels’ counts. The estimation we performed demonstrated better accuracy, it yielded a mean MWSR of 1.17(01).

Application of a CdTe Detector for Measurements of Mammographic X-ray Spectra

This work aims to characterize mammographic x-ray beams incident and transmitted by breast phantoms (from 0 to 45 mm) composed from known proportion of glandular and adipose tissue-equivalent materials. This study was performed for mammographic x-ray beams generated by a mammography equipment using different target/filter combinations (Mo/Mo, Mo/Rh and W/Rh). It was studied the modification of spectra shape of the beams transmitted through different thicknesses of these materials. It was also evaluated the penetrability of these transmitted beams by its correlations to the HVL, which were experimentally estimated and derived from the x-ray spectra measured using a spectrometry system with a CdTe detector. The x-ray spectra transmitted by the phantom with higher density presented lower intensity than those transmitted by those with lower density, as expected. The differences between the HVL values derived from the spectra and those estimated using air kerma measurements are lesser than 6% for about 88% of the spectra measured in this work. The expected spectra variations with phantom thickness, revealed by the measured transmitted x-ray spectra, were also confirmed by HVL measurements and agree with the estimated attenuation curves.The motivation of the study was related to the robustness of the spectra as a descriptor of radiation beams and the possibility of using these transmitted spectra for dose assessment related to mammographic procedures. We can conclude that developed method is able to characterize mammographic x-ray beams making it possible the use of this kind of data for dose assessment in mammography.

Change of tumor vascular reactivity during tumor growth and postchemotherapy observed by near-infrared spectroscopy.

Breast cancer is one of the most common cancers in females. To monitor chemotherapeutic efficacy for breast cancer, medical imaging systems such as x-ray mammography, computed tomography, magnetic resonance imaging, and ultrasound imaging have been used. Currently, it can take up to 3 to 6 weeks to see the tumor response from chemotherapy by monitoring tumor volume changes. We used near-infrared spectroscopy (NIRS) to predict breast cancer treatment efficacy earlier than tumor volume changes by monitoring tumor vascular reactivity during inhalational gas interventions. The results show that the amplitude of oxy-hemoglobin changes (vascular reactivity) during hyperoxic gas inhalation is well correlated with tumor growth and responded one day earlier than tumor volume changes after chemotherapy. These results may imply that NIRS with respiratory challenges can be useful in early detection of tumor and in the prediction of tumor response to chemotherapy.

Maximum intensity breast diffusion MRI for BI-RADS 4 lesions detected on X-ray mammography

To investigate an abbreviated, contrast-agent free diffusion-weighted (DW) breast magnetic resonance imaging (MRI) protocol that provides a single image for the radiologist to read in order to non-invasively examine Breast Imaging-Reporting and Data System (BI-RADS) 4 lesions detected using breast cancer screening X-ray mammography. This retrospective evaluation within a institutional review board-approved, prospective study included 115 women (mean 57 years, range 50-69 years) with BI-RADS 4 findings on X-ray mammography and indication for biopsy over a period of 15 months. Full diagnostic breast MRI (FDP) was performed prior to biopsy (1.5T). Maximum intensity breast diffusion (MIBD) images were generated from DW images (b=1,500mm/s2, 3mm section thickness) of the breast. MIBD and T2-weighted (T2W) images were read by two radiologists and compared to the diagnostic accuracy of an expert reading of the FDP with histopathology as the reference standard. The acquisition time of MIBD and T2W MRI was about 7 minutes. MIBD MRI provided a diagnostic accuracy of 87.93% (95% confidence interval [CI]: 80.58-93.24%) for R1 and 89.66% (95% CI: 82.63-94.54%) for R2. Expert reading of the FDP revealed a similar accuracy of 86.2% (95% CI: 78.67-91.43%). The positive predictive value (PPV) could be increased from 36.2% (95% CI: 28.02-45.28; X-ray mammography alone) to a mean PPV of 80.89% (R1 79.17%, R2 82.16%) using MIBD MRI. Mean reading time was 30 seconds (25%/75 percentile 24.5-41.25). MIBD MRI might be of supplemental value if added to the work-up of BI-RADS 4 X-ray mammography screening findings. MIBD MRI might help reduce the false-positive rate prior to biopsy for reference lesions at only limited expense of measurement and reading time.

Abstract 3742: Exposure burden for patients during an experimental study using a dual-energy contrast-enhanced spectral mammography

Abstract Mammography provides early micro-calcification recognition, that is important for further breast cancer (BC) diagnosis. Imaging choice for BC detection is X-ray mammography (MG) with the use of high-resolution digital modality combined with iodinated contrast agents. However, a conventional MG has some sensitivity limitations, especially in patients with densely treated breasts. Moreover, MG contributes radiation risk for BC that is correlated with an exposure to ionizing radiation. Patients, for whom MG study does not give a clear interpretation are often further diagnosed by contrast-enhanced breast MRI, the most sensitive BC detection technique. Alternatively, it is limited by higher costs, lower availability and increased false positives. Dual-energy contrast-enhanced spectral mammography (CESM) is a new method applied in BC that enables accurate detection of malignant breast lesions similar to breast MRI. The aim of this study was to compare the usefulness of CESM versus MG in BC detection. Additionally, doses given to the BC patients during imaging were compared. In this study, 250 consecutive women (144 MG vs. 105 CESM), that were screened using mammography between 2011 and 2014 were retrospectively enrolled in the study. The comparison of entrance surface air kerma and mean glandular dose values for both options were recorded, respectively and analyzed using different statistical and retrospective approach. Results of presented study showed that CESM might be a new diagnostic tool allowing an accurate detection of BC lesions, giving results similar to those received from magnetic resonance imaging. A good agreement found between sensitivity of the method and tumour diameters measurements based on CESM, supports this tool as a potential replacement for breast MRI in the preoperative evaluation of BC patients. However, a radiation burden for patients might be significantly higher than that for a standard full-field digital mammography procedure. In summary, each method has its own benefits with respect to specific applications that are further discussed in the study. Citation Format: Kamila Rawojc, Kamil Kisielewicz, Anna Dziecichowicz, Monika Tomaszuk, Anna Cepiga, Jankowska Anna, Cieśla Izabela, Najberg Dominika, Luczynska Elzbieta, Bartosz Kieltyka. Exposure burden for patients during an experimental study using a dual-energy contrast-enhanced spectral mammography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3742. doi:10.1158/1538-7445.AM2017-3742

High sensitivity non-invasive detection of calcifications deep inside biological tissue using Transmission Raman Spectroscopy.

The aim of this research was to develop a novel approach to probe non-invasively the composition of inorganic chemicals buried deep in large volume biological samples. The method is based on advanced Transmission Raman Spectroscopy (TRS) permitting chemical specific detection within a large sampling volume. The approach could be beneficial to chemical identification of the breast calcifications detected during mammographic X-ray procedures. The chemical composition of a breast calcification reflects the pathology of the surrounding tissue, malignant or benign and potentially the grade of malignancy. However, this information is not available from mammography, leading to excisional biopsy and histopathological assessment for a definitive diagnosis. Here we present, for the first time, a design of a new high performance deep Raman instrument and demonstrate its capability to detect type II calcifications (calcium hydroxyapatite) at clinically relevant concentrations and depths of around 40 mm in phantom tissue. This is around double the penetration depth achieved with our previous instrument design and around two orders of magnitude higher than that possible when using conventional Raman spectroscopy.

An investigation of the role of defect levels on the radiation response of synthetic diamond crystals when used as sensors for the detection of mammography X-rays

This study evaluates the role of defects on the performances of synthetic diamond sensors on exposure to mammography X-rays. Through systematic investigations, the main cause of instability of response of examined sensors necessitating pre-irradiation was isolated and ascribed to the presence of ambient light which has the effect of emptying shallow trapping levels. The changes in response between measurements in light and dark conditions varied from 2.8 ± 1.2% to 63.0 ± 0.3%. Sensitivities between 0.4 and 6.7nCGy−1mm−3 determined for the sensors varied with defect levels. The study indicates that differences in crystal quality due to the presence and influence of defects would cause a discrepancy in the dosimetric performances of various diamond detectors. Once a sensor plate is selected (based on the influence of defect levels) and coupled to the probe housing with the response of the diamond sensor stabilised and appropriately shielded from ambient light, daily priming is not needed.

Evaluation of Breast Masses by Sonomammography and X-ray Mammography in Correlation with Histopathological Findings

Abstract Introduction: Breast lumps are common presenting complaints in the female surgical outpatient department, which are due to varied breast pathologies. Breast infection most commonly affects women aged 18 to 50 years; in this age group, it can be divided into lactational and nonlactational infections. The process can affect the skin overlying the breast, where it can be a primary event, or it may be secondary to a lesion, such as sebaceous cyst or hidradenitis suppurativa. Aim: The aim of this article was to find out sonographic features of benign and malignant masses and correlate X-ray mammography and sonographic findings with histopathology with classification of all breast lesions according to the breast imaging reporting and data system final assessment categories (BI-RADS) (mammography). Materials and methods: This was a prospective diagnostic study conducted on 50 female patients from September 2015 to August 2016 in the Department of Radiodiagnosis in a tertiary care hospital. Results: In benign lesion, 24 (48%) of the patients had fibroadenoma, 2% intraductal papilloma, and 1 (2%) each had galactocele and tubercular abscess; in malignant lesion, 23 (46%) had ductal malignancy. Conclusion: The ultrasound features are helpful in differentiating benign from malignant masses. Classification of the lesions according to BI-RADS helps to improve the management of lesions.

Computer-aided diagnosis of mammographic masses based on a supervised content-based image retrieval approach

In this work, the incorporation of content-based image retrieval (CBIR) into computer aided diagnosis (CADx) is investigated, in order to contribute to the decision-making process of radiologists in the characterization of mammographic masses. The proposed scheme comprises two stages: A margin-specific supervised CBIR stage that retrieves images from reference cases along with a decision stage that is based on the retrieved items. The feature set utilized exploits state-of-the-art features along with a newly proposed texture descriptor, namely mHOG, targeted to capturing margin and core specific mass properties. Performance evaluation considers the CBIR and diagnosis stages separately and is addressed by using standard measures on an enhanced version of the widely adopted digital database for screening mammography (DDSM). The proposed scheme achieved improved performance of CADx of masses in X-ray mammography experimentally compared to the state-of-the-art.

Direct measurement of clinical mammographic x-ray spectra using a CdTe spectrometer.

To introduce and evaluate a method developed for the direct measurement of mammographic x-ray spectra using a CdTe spectrometer. The assembly of a positioning system and the design of a simple and customized alignment device for this application is described. A positioning system was developed to easily and accurately locate the CdTe detector in the x-ray beam. Additionally, an alignment device to line up the detector with the central axis of the radiation beam was designed. Direct x-ray spectra measurements were performed in two different clinical mammography units and the measured x-ray spectra were compared with computer-generated spectra. In addition, the spectrometer misalignment effect was evaluated by comparing the measured spectra when this device is aligned relatively to when it is misaligned. The positioning and alignment of the spectrometer have allowed the measurements of direct mammographic x-ray spectra in agreement with computer-generated spectra. The most accurate x-ray spectral shape, related with the minimal HVL value, and high photon fluence for measured spectra was found with the spectrometer aligned according to the proposed method. The HVL values derived from both simulated and measured x-ray spectra differ at most 1.3 and 4.5% for two mammography devices evaluated in this study. The experimental method developed in this work allows simple positioning and alignment of a spectrometer for x-ray spectra measurements given the geometrical constraints and maintenance of the original configurations of mammography machines.

Deterministic compressive sampling for high-quality image reconstruction of ultrasound tomography

BackgroundA well-known diagnostic imaging modality, termed ultrasound tomography, was quickly developed for the detection of very small tumors whose sizes are smaller than the wavelength of the incident pressure wave without ionizing radiation, compared to the current gold-standard X-ray mammography. Based on inverse scattering technique, ultrasound tomography uses some material properties such as sound contrast or attenuation to detect small targets. The Distorted Born Iterative Method (DBIM) based on first-order Born approximation is an efficient diffraction tomography approach. One of the challenges for a high quality reconstruction is to obtain many measurements from the number of transmitters and receivers. Given the fact that biomedical images are often sparse, the compressed sensing (CS) technique could be therefore effectively applied to ultrasound tomography by reducing the number of transmitters and receivers, while maintaining a high quality of image reconstruction.MethodsThere are currently several work on CS that dispose randomly distributed locations for the measurement system. However, this random configuration is relatively difficult to implement in practice. Instead of it, we should adopt a methodology that helps determine the locations of measurement devices in a deterministic way. For this, we develop the novel DCS-DBIM algorithm that is highly applicable in practice. Inspired of the exploitation of the deterministic compressed sensing technique (DCS) introduced by the authors few years ago with the image reconstruction process implemented using l1 regularization.ResultsSimulation results of the proposed approach have demonstrated its high performance, with the normalized error approximately 90% reduced, compared to the conventional approach, this new approach can save half of number of measurements and only uses two iterations. Universal image quality index is also evaluated in order to prove the efficiency of the proposed approach.ConclusionsNumerical simulation results indicate that CS and DCS techniques offer equivalent image reconstruction quality with simpler practical implementation. It would be a very promising approach in practical applications of modern biomedical imaging technology.

High Energy Resolution Hyperspectral X-Ray Imaging for Low-Dose Contrast-Enhanced Digital Mammography.

Contrast-enhanced digital mammography (CEDM) is an alternative to conventional X-ray mammography for imaging dense breasts. However, conventional approaches to CEDM require a double exposure of the patient, implying higher dose, and risk of incorrect image registration due to motion artifacts. A novel approach is presented, based on hyperspectral imaging, where a detector combining positional and high-resolution spectral information (in this case based on Cadmium Telluride) is used. This allows simultaneous acquisition of the two images required for CEDM. The approach was tested on a custom breast-equivalent phantom containing iodinated contrast agent (Niopam 150®). Two algorithms were used to obtain images of the contrast agent distribution: K-edge subtraction (KES), providing images of the distribution of the contrast agent with the background structures removed, and a dual-energy (DE) algorithm, providing an iodine-equivalent image and a water-equivalent image. The high energy resolution of the detector allowed the selection of two close-by energies, maximising the signal in KES images, and enhancing the visibility of details with the low surface concentration of contrast agent. DE performed consistently better than KES in terms of contrast-to-noise ratio of the details; moreover, it allowed a correct reconstruction of the surface concentration of the contrast agent in the iodine image. Comparison with CEDM with a conventional detector proved the superior performance of hyperspectral CEDM in terms of the image quality/dose tradeoff.

Monte Carlo calculation of conversion coefficients for dose estimation in mammography based on a 3D detailed breast model.

At present, the Chinese specification for testing of quality control in x-ray mammography is based on a simple breast model, and does not consider the glandular tissue distribution in the breast. In order to more precisely estimate the mean glandular dose (MGD) in mammography for Chinese women, a three-dimensional (3D) detailed breast model based on realistic structures in the breast and Chinese female breast parameters was built and applied in this study. To characterize the Chinese female breast, Chinese female breast parameters including breast size, compressed breast thickness (CBT), and glandular content were investigated in this study. A mathematical model with the detailed breast structures was constructed based on the Chinese female breast parameters. The mathematical model was then converted to a voxel model with voxels. The voxel model was compressed in craniocaudal (CC) view to obtain a deformation model. The compressed breast model was combined with the Chinese reference adult female whole-body voxel phantom (CRAF) to study the effects of backscatter from the female body. Monte Carlo simulations of the glandular dose in mammography were performed with Geant 4. The glandular tissue dose conversion coefficients for breasts with different glandular contents (5%, 25%, 50%, 75%, and 100% glandularity) and CBTs (3cm, 4cm, 5cm, and 6cm) were calculated, respectively, at various x-ray tube voltages (25 kV, 28 kV, 30 kV, 32 kV, and 35 kV) for various target/filter combinations (Mo/Mo, Mo/Rh, Rh/Rh, and W/Rh). A series of glandular tissue dose conversion coefficients for dose estimation in mammography were calculated. The conversion coefficients calculated in this study were compared with those estimated with the simple breast model. A discrepancy of 5.4-38.0% was observed. This was consistent with the results obtained from the realistic breast models in the literature. A 3D detailed breast model with realistic structures in the breast was constructed based on the Chinese female breast parameters. It was used to calculate glandular tissue dose conversion coefficients for mammography. Although the accuracy of the proposed model could not be directly assessed, the consistency of the obtained results with previously performed analyses increases the confidence in the applicability of the proposed model. The proposed model could be used in dose estimation and dose optimization for mammography of Chinese women.

Detectability comparison between a high energy x-ray phase sensitive and mammography systems in imaging phantoms with varying glandular-adipose ratios

The objective of this study was to demonstrate the potential benefits of using high energy x-rays in comparison with the conventional mammography imaging systems for phase sensitive imaging of breast tissues with varying glandular-adipose ratios.This study employed two modular phantoms simulating the glandular (G) and adipose (A) breast tissue composition in 50 G–50 A and 70 G–30 A percentage densities. Each phantom had a thickness of 5 cm with a contrast detail test pattern embedded in the middle. For both phantoms, the phase contrast images were acquired using a micro-focus x-ray source operated at 120 kVp and 4.5 mAs, with a magnification factor (M) of 2.5 and a detector with a 50 µm pixel pitch. The mean glandular dose delivered to the 50 G–50 A and 70 G–30 A phantom sets were 1.33 and 1.3 mGy, respectively. A phase retrieval algorithm based on the phase attenuation duality that required only a single phase contrast image was applied. Conventional low energy mammography images were acquired using GE Senographe DS and Hologic Selenia systems utilizing their automatic exposure control (AEC) settings. In addition, the automatic contrast mode (CNT) was also used for the acquisition with the GE system. The AEC mode applied higher dose settings for the 70 G–30 A phantom set. As compared to the phase contrast images, the dose levels for the AEC mode acquired images were similar while the dose levels for the CNT mode were almost double.The observer study, contrast-to-noise ratio and figure of merit comparisons indicated a large improvement with the phase retrieved images in comparison to the AEC mode images acquired with the clinical systems for both density levels. As the glandular composition increased, the detectability of smaller discs decreased with the clinical systems, particularly with the GE system, even at higher dose settings. As compared to the CNT mode (double dose) images, the observer study also indicated that the phase retrieved images provided similar or improved detection for all disc sizes except for the disk diameters of 2 mm and 1 mm for the 50 G–50 A phantom and 3 mm and 0.5 mm for the 70 G–30 A phantom.This study demonstrated the potential of utilizing a high energy phase sensitive x-ray imaging system to improve lesion detection and reduce radiation dose when imaging breast tissues with varying glandular compositions.

QUALITY CONTROL X RAYS MAMMOGRAPHY IN THE EFFORT MITIGATION INCREASING NUMBER OF CANCER PATIENTS

Abstract. Early detection of breast cancer is the first step in prevention that can be done by women, therefore when one is diagnosed with breast cancer, the appropriate treatment can be performed quickly and accurately. Early diagnosis of breast cancer can be a way of mitigation in preventing breast cancer through the use of mammography. Bureau of Radiology as said by The Joint Commission on Accreditation of Hospitals (JHCA) stated that one of the responsibilities of the radiology unit is to control the quality of service which aims to minimize the radiographic image repetition factor; as well as maximizes the quality of radiographic image. Quality control tests are an effort that is needed on the mammography X-ray diagnostics tools. This is done to maintain the quality of expected output. The parameters that are included within the radiation output are the magnitude of current and the voltage of tube that are produced; therefore they remained constant and correspond to the recommended standard. Bureau of Radiological Health, as said by JHCA mentioned that to control the quality of image which will minimize the radiographic image repetition and maximizes the quality of radiographic image. Therefore the radiation output will not be dangerous later. The early stage of the quality control test on the machine was conducted by setting all the filtrations which were placed to capture the x-ray on the x-ray plane tube with minimum value. Then, ionization chamber is placed on the test subject points; right after that the distance between it to the radiation source is noted. The x-ray film is place on a film on the compression table of the patient and the distance between film and the focus point is noted. This is then exposed using a target filter Mo/Mo by setting the current as well as variation the voltage and time. The standard voltage measurements are 20-33kVp. This data is from the observations of time exposure; the output value is then noted. The above procedure is conducted from the minimum voltage to the maximum voltage. The output ray is measured for each voltage. The same procedure is conducted to the target filter Mo/RH. The results obtained are that the greater the input voltage and current will subsequently produce greater doses, therefore the exposure has exceeded the standard limit 0.1 mHy with longer exposure time. The HVL density thickness on the mammography X-ray machine determined the quality of the beam and the doses of x-ray exposure on the mammography machine. The output stability of x-ray beam exposure in the mammography machine mode Mo/Mo still fulfill the standard which is the value of 69% Keywords: Quality Control, Sinar-X, mammography, Mp/Mo, Mo/RH

3D volume reconstruction from serial breast specimen radiographs for mapping between histology and 3D whole specimen imaging.

PurposeIn breast imaging, radiological in vivo images, such as x‐ray mammography and magnetic resonance imaging (MRI), are used for tumor detection, diagnosis, and size determination. After excision, the specimen is typically sliced into slabs and a small subset is sampled. Histopathological imaging of the stained samples is used as the gold standard for characterization of the tumor microenvironment. A 3D volume reconstruction of the whole specimen from the 2D slabs could facilitate bridging the gap between histology and in vivo radiological imaging. This task is challenging, however, due to the large deformation that the breast tissue undergoes after surgery and the significant undersampling of the specimen obtained in histology. In this work, we present a method to reconstruct a coherent 3D volume from 2D digital radiographs of the specimen slabs.MethodsTo reconstruct a 3D breast specimen volume, we propose the use of multiple target neighboring slices, when deforming each 2D slab radiograph in the volume, rather than performing pairwise registrations. The algorithm combines neighborhood slice information with free‐form deformations, which enables a flexible, nonlinear deformation to be computed subject to the constraint that a coherent 3D volume is obtained. The neighborhood information provides adequate constraints, without the need for any additional regularization terms.ResultsThe volume reconstruction algorithm is validated on clinical mastectomy samples using a quantitative assessment of the volume reconstruction smoothness and a comparison with a whole specimen 3D image acquired for validation before slicing. Additionally, a target registration error of 5 mm (comparable to the specimen slab thickness of 4 mm) was obtained for five cases. The error was computed using manual annotations from four observers as gold standard, with interobserver variability of 3.4 mm. Finally, we illustrate how the reconstructed volumes can be used to map histology images to a 3D specimen image of the whole sample (either MRI or CT).ConclusionsQualitative and quantitative assessment has illustrated the benefit of using our proposed methodology to reconstruct a coherent specimen volume from serial slab radiographs. To our knowledge, this is the first method that has been applied to clinical breast cases, with the goal of reconstructing a whole specimen sample. The algorithm can be used as part of the pipeline of mapping histology images to ex vivo and ultimately in vivo radiological images of the breast.

Natural history of breast cancer: a systematic review of worldwide randomized controlled trials of mammography screening

Objective: To parameterize the 1-year transition probabilities between different health status of the natural history of breast cancer based on the data of randomized controlled trial of X-ray mammography screening worldwide. Methods: Based on the breast cancer screening randomized controlled trials defined by a mammography screening review from the Cochrane 2013 and the International Agency for Research on Cancer, a systematic review was initiated in PubMed by searching names of the key investigators of the trials, combined with the diseases, screening intervention and outcome indicators. If applicable, all the original cumulative incidence rates were converted into one-year transition rate, using the life-table approach considering time length of follow-up. Results: A total of 23 reports from 9 RCTs were included. The data on transition rate between the healthy status to precancerous lesions was absent. The 1-year transition rate from health to carcinoma in situ was 17.78 to 50.21 per 100 000 persons in the intervention group and 9.16 to 26.84 per 100 000 persons in the control group. Correspondingly, the 1-year transition rate from health to breast cancer (including carcinoma in situ and invasive cancer) were estimated as 143.75 to 316.97 per 100 000 persons in the intervention group, and 141.45 to 288.84 per 100 000 persons in the control group. Furthermore, the transition rate from the healthy status to invasive breast cancer was 159.79 to 264.60 per 100 000 persons in intervention group and 170.12 to 255.33 per 100 000 persons in control group. The transition rate from carcinoma in situ to invasive breast cancer varied among different pathological types. Conclusions: The most common natural history states of reported by the included trials involved the full healthy status, carcinoma in situ and invasive breast cancer. The findings of transition rates between different health statuses will be informative for future model development of natural history studies of breast cancer. Information in relation to breast precancerous lesions still limited and needs to be further addressed.

Prediction of malignancy by a radiomic signature from contrast agent-free diffusion MRI in suspicious breast lesions found on screening mammography.

To assess radiomics as a tool to determine how well lesions found suspicious on breast cancer screening X-ray mammography can be categorized into malignant and benign with unenhanced magnetic resonance (MR) mammography with diffusion-weighted imaging and T2 -weighted sequences. From an asymptomatic screening cohort, 50 women with mammographically suspicious findings were examined with contrast-enhanced breast MRI (ceMRI) at 1.5T. Out of this protocol an unenhanced, abbreviated diffusion-weighted imaging protocol (ueMRI) including T2 -weighted, (T2 w), diffusion-weighted imaging (DWI), and DWI with background suppression (DWIBS) sequences and corresponding apparent diffusion coefficient (ADC) maps were extracted. From ueMRI-derived radiomic features, three Lasso-supervised machine-learning classifiers were constructed and compared with the clinical performance of a highly experienced radiologist: 1) univariate mean ADC model, 2) unconstrained radiomic model, 3) constrained radiomic model with mandatory inclusion of mean ADC. The unconstrained and constrained radiomic classifiers consisted of 11 parameters each and achieved differentiation of malignant from benign lesions with a .632 + bootstrap receiver operating characteristics (ROC) area under the curve (AUC) of 84.2%/85.1%, compared to 77.4% for mean ADC and 95.9%/95.9% for the experienced radiologist using ceMRI/ueMRI. In this pilot study we identified two ueMRI radiomics classifiers that performed well in the differentiation of malignant from benign lesions and achieved higher performance than the mean ADC parameter alone. Classification was lower than the almost perfect performance of a highly experienced breast radiologist. The potential of radiomics to provide a training-independent diagnostic decision tool is indicated. A performance reaching the human expert would be highly desirable and based on our results is considered possible when the concept is extended in larger cohorts with further development and validation of the technique. 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:604-616.

Evaluation of patient dose saving in grid-less x-ray mammography acquisition compared with full field digital mammography (FFDMG) acquisition

Purpose. To investigate the patient radiation dose saving of grid-less x-ray mammography acquisitions compared with conventional full-field digital mammography (FFDMG). Methods and materials. The Siemens Inspiration MAMMOMAT PRIME system with software based scatter correction was used to investigate the dose saving in grid-less acquisition compared with conventional full-field digital mammography (FFDMG) acquisitions. A Piranha 657 solid-state detector was used to measure the entrance exposure. The entrance exposure was directly measured on different PMMA thicknesses of 20–70 mm in steps of 10 mm. The PMMA block thicknesses were then converted to an equivalent compressed breast tissue thicknesses. The average glandular dose (AGD) is calculated. Results. Dose reduction in both the directly measured entrance exposure and the calculated AGD is between 13% and 32% in the grid-less mammography acquisition. The contrast to noise ratio calculated in the grid-less and the FFDMG acquisition also was the same. Conclusion. It was possible to save patient dose (13%–32%) in grid-less mammography acquisition without affecting the image quality.

Spectral extrapolation for ultra-wide band radio frequency super-resolution tumor localization in the breast.

The use of ultra-wide band (UWB) radio frequency (RF) as an alternative to x-ray mammography for the detection and localization of breast tumors has been an area of focused research over the last decade. Unlike x-rays, UWB RF is non-ionizing and poses no risk of inducing cancer in examined patients. However, the reduction in operating frequency of UWB RF compared to x-rays results in much poorer localization when using classical space-time adaptive signal processing. This work investigates the synergistic use of a temporal signal spectrum extrapolation technique and contemporary basis pursuit de-noising (BPDN) beamforming to achieve medically relevant tumor localization accuracy within a heterogeneous simulated breast volume. If the beamforming process is viewed as a matched filtering operation, the spectrum extrapolation technique artificially increases the bandwidth of the received signal to afford much sharper correlations and hence contributing to increased localization accuracy. BPDN also contributes to increased localization accuracy by employing L1-norm constraints which shows marked clutter suppression effects in this context.