Cone-beam Breast Computed Tomography Research Articles

Comparative analysis of cone‐beam breast computed tomography and digital breast tomosynthesis for breast cancer diagnosis: A comprehensive study on reconstruction algorithms

AbstractBreast cancer (BC) is the most commonly diagnosed non‐skin cancer in women. To achieve early and accurate diagnosis, three‐dimensional (3D) cone‐beam breast computed tomography (CBBCT) and digital breast tomosynthesis (DBT) modalities are used. Importantly, the comparison of reconstruction accuracy of both CBBCT and DBT has rarely been investigated, thus constituting a research gap. This study systematically investigated the performances of the CBBCT and DBT for different reconstruction algorithms using both BR3D breast phantom and breast images. We acquired clinical breast images and scanned the BR3D phantom for additional breast images. These acquired images were used to simulate projection data using predefined CBBCT and DBT geometries. The simulated projections were reconstructed using five different reconstruction algorithms. To evaluate the reconstruction accuracy, we calculated average image quality assessment (IQA) indices, including peak signal‐to‐noise ratio (PSNR), structural similarity index (SSIM), root mean square error (RMSE), and others, across different algorithms and modalities. The pooled PSNR, SSIM, and RMSE for DBT and CBBCT images are (31.6265 ± 0.8725), (0.9353 ± 0.0077), and (0.0270 ± 0.0025) and (29.7007 ± 0.9249), (0.9136 ± 0.0130), and (0.0342 ± 0.0040), which implies that the overall IQA indices of DBT are superior to CBBCT; therefore, DBT tends to reveal more BC detectability as the diagnosis outcome would largely depend on good quality images. The results show that DBT gives an improved result for all algorithms compared to CBBCT, although further experimental trials may be needed to establish the findings fully. The findings suggest that using DBT may enhance the accuracy of BC diagnosis compared to CBBCT due to its superior image quality in clinical practice, emphasizing the importance of selecting optimal reconstruction algorithms for improved diagnostic outcomes.

Accuracy of cone-beam breast computed tomography for assessing breast cancer tumor size-comparison with breast magnetic resonance imaging.

Accurate preoperative assessment of tumor size is important in developing a surgical plan for breast cancer. The purpose of this study was to evaluate the accuracy of cone-beam breast computed tomography (CBBCT) and magnetic resonance imaging (MRI) in the assessment of tumor size and to analyze the factors influencing the discordance. In this retrospective study, patients with breast cancer who underwent preoperative contrast-enhanced CBBCT (CE-CBBCT) and dynamic contrast-enhanced MRI (DCE-MRI) and received a complete pathologic diagnosis from August 2020 to December 2021 were included, using the pathological result as the gold standard. Two radiologists assessed the CBBCT and MRI features and measured the tumor size with a 2-week washout period. Intraclass correlation coefficient (ICC) and Bland-Altman analyses were used to assess inter-observer reproducibility and agreement based on CBBCT, MRI and pathology. Univariate analyses of differences in clinical, pathological and CBBCT/MRI features between the concordant and discordant groups was performed using the t-test, Mann-Whitney U-test, Chi-squared test and Fisher's exact test. Multivariate analyses were used to identify factors associated with discordance of CBBCT/MRI with pathology. A total of 115 female breast cancer patients (115 lesions) were included. All patients had a single malignant tumor of the unilateral breast. The reproducibility and the agreement ranged from moderate to excellent (ICC =0.607-0.983). Receiver operating characteristic (ROC) analyses showed that the cut-off values of CBBCT-pathology and MRI-pathology discordance were 2.25 and 2.65 cm, respectively. CBBCT/MRI-pathology concordance was significantly associated with the extent of pathology, lesion type, presence of calcification, human epidermal growth factor receptor 2 (HER2) status and fatty infiltration (P<0.05). In lesions containing calcification, the difference of CBBCT-pathology was significantly smaller than MRI-pathology (P=0.021). Non-mass enhancement (NME) was the main predictor of CBBCT- or MRI-pathology discordance [odds ratio (OR) =3.293-6.469, P<0.05], and HER2 positivity was a predictor of CBBCT-pathology discordance (OR =3.514, P=0.019). CBBCT and MRI have comparable accuracy in measurement of tumor size, and CBBCT is advantageous in assessing the size of calcified lesions. NME and HER2 positivity are significant predictors of CBBCT-pathology discordance. This suggests that CBBCT might serve as an alternative imaging technique to assess tumor size when patients do not tolerate MRI.

Virtual dosimetry study with three cone-beam breast computed tomography scanners using a fast GPU-based Monte Carlo code

Objective. To compare the dosimetric performance of three cone-beam breast computed tomography (BCT) scanners, using real-time Monte Carlo-based dose estimates obtained with the virtual clinical trials (VCT)-BREAST graphical processing unit (GPU)-accelerated platform dedicated to VCT in breast imaging. Approach. A GPU-based Monte Carlo (MC) code was developed for replicating in silico the geometric, x-ray spectra and detector setups adopted, respectively, in two research scanners and one commercial BCT scanner, adopting 80 kV, 60 kV and 49 kV tube voltage, respectively. Our cohort of virtual breasts included 16 anthropomorphic voxelized breast phantoms from a publicly available dataset. For each virtual patient, we simulated exams on the three scanners, up to a nominal simulated mean glandular dose of 5 mGy (primary photons launched, in the order of 1011–1012 per scan). Simulated 3D dose maps (recorded for skin, adipose and glandular tissues) were compared for the same phantom, on the three scanners. MC simulations were implemented on a single NVIDIA GeForce RTX 3090 graphics card. Main results. Using the spread of the dose distribution as a figure of merit, we showed that, in the investigated phantoms, the glandular dose is more uniform within less dense breasts, and it is more uniformly distributed for scans at 80 kV and 60 kV, than at 49 kV. A realistic virtual study of each breast phantom was completed in about 3.0 h with less than 1% statistical uncertainty, with 109 primary photons processed in 3.6 s computing time. Significance. We reported the first dosimetric study of the VCT-BREAST platform, a fast MC simulation tool for real-time virtual dosimetry and imaging trials in BCT, investigating the dose delivery performance of three clinical BCT scanners. This tool can be adopted to investigate also the effects on the 3D dose distribution produced by changes in the geometrical and spectrum characteristics of a cone-beam BCT scanner.

Head-to-head comparison of cone-beam breast computed tomography and mammography in the diagnosis of primary breast cancer: A systematic review and meta-analysis

IntroductionTo compare the diagnostic performance of cone-beam breast computed tomography (CBBCT) and mammography (MG) in primary breast cancer. MethodsPubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang DATA, and China Science and Technology Journal databases were searched comprehensively from inception to March 2023. Sensitivity and specificity were calculated using bivariate random-effects models, and a summary receiver operating characteristic (SROC) curve was constructed. Bivariate I2 statistics and meta-regression analyses were also performed. The differences in diagnostic performance between CBBCT and MG were analysed using Z-test statistics. Clinical utility was explored using Fagan’s nomogram, and quality assessment was conducted utilising the Quality Assessment of Diagnostic Accuracy Studies-2 checklist. ResultsThe summary sensitivity and specificity for CBBCT in diagnosing primary breast cancer were 0.92 (95 % CI: 0.87–0.94) and 0.79 (95 % CI: 0.71–0.85), respectively, and the area under the curve (AUC) of the SROC was 0.93 (95 % CI: 0.90–0.95). For MG, the summary sensitivity and specificity were 0.77 (95 % CI: 0.69–0.83) and 0.75 (95 % CI: 0.66–0.82), respectively, with an AUC of 0.83 (95 % CI: 0.80–0.86). The Z-test revealed that the summary sensitivity of CBBCT was significantly higher than that of MG (P < 0.001). Additionally, the summary AUC of CBBCT was significantly higher than that of MG (P < 0.001). ConclusionThe diagnostic performance of CBBCT for primary breast cancer was better than that of MG. However, the results of both the CBBCT and MG are based on studies with small sample sizes. Further studies with larger sample sizes and more comprehensive designs are required to address this issue.

Dedicated Cone-Beam Breast CT: Reproducibility of Volumetric Glandular Fraction with Advanced Image Reconstruction Methods.

Dedicated cone-beam breast computed tomography (CBBCT) is an emerging modality and provides fully three-dimensional (3D) images of the uncompressed breast at an isotropic voxel resolution. In an effort to translate this modality to breast cancer screening, advanced image reconstruction methods are being pursued. Since radiographic breast density is an established risk factor for breast cancer and CBBCT provides volumetric data, this study investigates the reproducibility of the volumetric glandular fraction (VGF), defined as the proportion of fibroglandular tissue volume relative to the total breast volume excluding the skin. Four image reconstruction methods were investigated: the analytical Feldkamp-Davis-Kress (FDK), a compressed sensing-based fast, regularized, iterative statistical technique (FRIST), a fully supervised deep learning approach using a multi-scale residual dense network (MS-RDN), and a self-supervised approach based on Noise-to-Noise (N2N) learning. Projection datasets from 106 women who participated in a prior clinical trial were reconstructed using each of these algorithms at a fixed isotropic voxel size of (0.273 mm3). Each reconstructed breast volume was segmented into skin, adipose, and fibroglandular tissues, and the VGF was computed. The VGF did not differ among the four reconstruction methods (p = 0.167), and none of the three advanced image reconstruction algorithms differed from the standard FDK reconstruction (p > 0.862). Advanced reconstruction algorithms developed for low-dose CBBCT reproduce the VGF to provide quantitative breast density, which can be used for risk estimation.

Reference Range of CT Value in NC-CBBCT Based on Female Breast Structure.

As a new high-resolution three-dimensional CT imaging technology, the essential reference range of CT values in Cone-beam breast computed tomography (CBBCT) has not been established to date. To determine the reference range of computed tomography (CT) values in CBBCT for clinical breast examination. In total, 913 cases (1167 lateral) were subject to CBBCT. CT values of the glandular tissue, fat and different quadrants and different distances of CBBCT images were analyzed. The nipple and muscle were also evaluated. A total of 672 lateral breasts were included in the normal group for investigation. The reference range of the absolute CT value of the chest wall muscle is -136.68~43.36 HU. The reference range of the absolute CT value of the nipple is 176.39~334.02 HU. The reference range of the absolute CT value of fat is -190.4~-63.67HU, and of glandular tissue is -12.2~199.07HU. Our results firstly established the baseline CT values of Non-contrast CBBCT in female breasts, which will benefit cancer screening and lesion locating. The closer the normal breast fat and glandular tissue is to the nipple, the greater the CT value. The older the age, the lower the density. The CT values of fat are unstable in a distance of less than 5 cm, and the CT values of glandular tissues are relatively stable. The difference between the upper and lower quadrants is significant in the same lateral breast and the same section.

Diagnostic accuracy of cone-beam breast computed tomography and head-to-head comparison of digital mammography, magnetic resonance imaging and cone-beam breast computed tomography for breast cancer: a systematic review and meta-analysis.

Cone-beam breast computed tomography (CBBCT) is a new breast imaging technique, however, CBBCT is not yet widely used, and its future application will depend on its diagnostic potential and application value. Therefore, it is of great clinical significance to systematically review and analyze the diagnostic accuracy of CBBCT for breast cancer detection in existing studies and compare it with other traditional imaging methods for the diagnosis of breast lesions. We searched PubMed, Embase, Web of Science, and Chinese databases until August 2022 for relevant papers. Studies evaluating the diagnostic accuracy of CBBCT in women with suspected breast cancer were included. Each study's quality was evaluated using the Quality Assessment of Diagnostic Performance Studies-2 (QUADAS-2) instrument. Eighteen studies with a total of 1,792 patients were included in the analysis. The overall pooled sensitivity and specificity of CBBCT in diagnosing breast cancer were 0.95 [95% confidence interval (CI): 0.91-0.97] and 0.72 (95% CI: 0.62-0.80), respectively. The area under the curve (AUC) for CBBCT was 0.92 (95% CI: 0.90-0.94). In a head-to-head comparison of CBBCT and digital mammography (DM), eight trials with 992 patients were included in the study, and the AUCs for CBBCT and DM were 0.94 (95% CI: 0.92-0.96) and 0.83 (95% CI: 0.80-0.83), respectively. In a head-to-head comparison of CBBCT and magnetic resonance imaging (MRI), four trials with 203 patients were included in the analysis; the AUC for CBBCT and MRI were 0.88 (95% CI: 0.85-0.91) and 0.96 (95% CI: 0.94-0.97), respectively. This meta-analysis of CBBCT test accuracy indicated encouraging diagnostic performance. In the summary of head-to-head comparative studies, there is a tendency for CBBCT to have greater diagnostic accuracy than DM, although its diagnostic performance is marginally inferior to that of MRI. However, the meta-analysis results were derived from studies with limited sample sizes. There is a need for more extensive research in this setting.

CT values of contrast-enhanced CBBCT: A useful diagnostic tool for benign and malignant breast lesions.

Computed tomography (CT) value studies of cone-beam breast CT (CBBCT) mainly focus on the enhancement value or enhancement rate, and there has been no study on the CT value (Hounsfield units [HU]) of the lesion itself. To investigate the CT values under contrast-enhanced CBBCT (CE-CBBCT) and non-contrast-enhanced CBBCT (NC-CBBCT) in scanning for the differential diagnosis of benign and malignant breast lesions. A retrospective analysis was performed on 189 cases of mammary glandular tissues that underwent NC-CBBCT and CE-CBBCT examination. The qualitative CT values of the lesions, standardized Δ(L-A), standardized Δ*(L - G), standardized Δ(L-A) (Post 1st-Pre), and standardized Δ*(L-G) (Post 2nd-Post 1st) between the benign and malignant groups were compared. Prediction performance was evaluated using receiver operating characteristic (ROC) curves. In total, 58 cases were included in the benign group, 79 cases were included in the malignant group, and 52 cases were included in the normal group. The best diagnostic thresholds of CT values for L (Post 1st-Pre), Δ(L-A) (Post 1st-Pre), and Δ*(L-G) (Post 1st-Pre) were 49.5, 44, and 64.8 HU, respectively. The Δ(L-A) Post-1st rate values of CBBCT had medium diagnostic efficacy (AUC = 0.74, sensitivity = 76.6%, specificity = 69.4%). CE-CBBCT can improve the diagnostic efficiency of breast lesions compared with NC-CBBCT. The CT values (HU) of lesions do not need to be standardized with fat and can be directly used in clinical differential diagnosis. The first contrast phase (60 s) is recommended to reduce the radiation exposure.

The Research Progress of Cone-Beam Breast Computed Tomography in Clinical Application

Cone-beam breast computed tomography (CBBCT) is a specialized imaging modality for breast examination that can generate high-resolution three-dimensional images with 3D isotropic resolution. This method has high sensitivity and better displays breast cancer lesions and microcalcifications, especially in the dense breast. When combined with CBBCT plain and enhanced scans, the efficiency of diagnosis and treatment can be further improved. Enhanced CT scans provide a better display of the morphological characteristics of tumor lesions, surrounding tissues, and blood vessels, thereby providing more comprehensive diagnostic information. The imaging manifestations of breast cancer on CBBCT are closely related to the molecular subtypes and immunohistochemical receptor status of the tumor. By incorporating imaging characteristics, the molecular subtypes, and the status of immunohistochemical receptors of breast cancer, the diagnosis and evaluation of the disease can be predicted and assessed accurately. In recent years, CBBCT has shown great potential in the diagnosis and evaluation of breast cancer. This article provides a review of the operational characteristics of cone beam breast CT and the recent research progress in the diagnosis and evaluation of breast diseases.

Dedicated cone-beam breast CT: Data acquisition strategies based on projection angle-dependent normalized glandular dose coefficients.

Dedicated cone-beam breast computed tomography (CBBCT) using short-scan acquisition is being actively investigated to potentially reduce the radiation dose to the breast. This would require determining the optimal x-ray source trajectory for such short-scan acquisition. To quantify the projection angle-dependent normalized glandular dose coefficient ( ) in CBBCT, referred to as angular , so that the x-ray ray source trajectory that minimizes the radiation dose to the breast for short-scan acquisition can be determined. A cohort of 75 CBBCT clinical datasets was segmented and used to generate three breast models - (I) patient-specific breast with heterogeneous fibroglandular tissue distribution and real breast shape, (II) patient-specific breast shape with homogeneous tissue distribution and matched fibroglandular weight fraction, and (III) homogeneous semi-ellipsoidal breast with patient-specific breast dimensions and matched fibroglandular weight fraction, which corresponds to the breast model used in current radiation dosimetry protocols. For each clinical dataset, the angular was obtained at 10 discrete angles, spaced 36° apart, for full-scan, circular, x-ray source trajectory from Monte Carlo simulations. Model III is used for validating the Monte Carlo simulation results. Models II and III are used to determine if breast shape contributes to the observed trends in angular . A geometry-based theory in conjunction with center-of-mass ( ) based distribution analysis is used to explain the projection angle-dependent variation in angular . The theoretical model predicted that the angular will follow a sinusoidal pattern and the amplitude of the sinusoid increases when the center-of-mass of fibroglandular tissue ( ) is farther from the center-of-mass of the breast ( ). It also predicted that the angular will be minimized at x-ray source positions complementary to the . The was superior to the in 80% (60/75) of the breasts. From Monte Carlo simulations and for homogeneous breasts (models II and III), the deviation in breast shape from a semi-ellipsoid had minimal effect on angular and showed less than 4% variation. From Monte Carlo simulations and for model I, as predicted by our theory, the angular followed a sinusoidal pattern with maxima and minima at x-ray source positions superior and inferior to the breast, respectively. For model I, the projection angle-dependent variation in angular was 16.4%. The heterogeneous tissue distribution affected the angular more than the breast shape. For model I, the angular was lowest when the x-ray source was inferior to the breast. Hence, for short-scan CBBCT acquisition with aligned with axis-of-rotation, an x-ray source trajectory inferior to the breast is preferable and such an acquisition spanning 205° can potentially reduce the mean glandular dose by up to 52%.

Imaging manifestations of idiopathic granulomatous lobular mastitis on cone-beam breast computed tomography

PurposeTo evaluate the imaging manifestations of idiopathic granulomatous mastitis (IGM) on cone-beam breast computed tomography (CBBCT). MethodsWe retrospectively evaluated the clinical data of 22 female patients (mean age, 34.73 ± 10.41 years; range 20–58 years) with IGM pathologically confirmed by biopsy or resection. The non-contrast-enhanced CBBCT features, contrast-enhanced CBBCT features, contrast enhancement rate, time-density curve (TDC) and Breast Imaging-Reporting and Data System category of IGM were assessed. The contrast enhancement rates of IGM lesions at 60 s, 120 s and 180 s after injection of contrast agent were compared using ANOVA. ResultsAll 22 patients with IGM showed non-mass enhancement on CBBCT. Approximately 40.9% (9/22) of IGM lesions displayed diffuse patchy or focal nodular enhancement on CBBCT, 31.8% (7/22) showed mammary duct dilation, 13.6% (3/22) showed pseudocystic appearance, and 13.6% (3/22) manifested as honeycomb cysts. Among the 22 patients, 72.7% (16/22) displayed type I TDC (persistently enhancing pattern) and 27.3% showed type II TDC (plateau pattern) on contrast-enhanced CBBCT. ConclusionsIGM mainly manifests as non-mass enhancement on CBBCT, with persistently enhancing or plateau TDC. CBBCT efficiently displays detailed features of IGM with high-density resolution and hemodynamic characteristics.

Comparison of Diagnostic Test Accuracy of Cone-Beam Breast Computed Tomography and Digital Breast Tomosynthesis for Breast Cancer: A Systematic Review and Meta-Analysis Approach.

Background: Cone-beam breast computed tomography (CBBCT) and digital breast tomosynthesis (DBT) remain the main 3D modalities for X-ray breast imaging. This study aimed to systematically evaluate and meta-analyze the comparison of diagnostic accuracy of CBBCT and DBT to characterize breast cancers. Methods: Two independent reviewers identified screening on diagnostic studies from 1 January 2015 to 30 December 2021, with at least reported sensitivity and specificity for both CBBCT and DBT. A univariate pooled meta-analysis was performed using the random-effects model to estimate the sensitivity and specificity while other diagnostic parameters like the area under the ROC curve (AUC), positive likelihood ratio (), and negative likelihood ratio () were estimated using the bivariate model. Results: The pooled sensitivity specificity, and and AUC at 95% confidence interval are 86.7% (80.3–91.2), 87.0% (79.9–91.8), 6.28 (4.40–8.96), 0.17 (0.12–0.25) and 0.925 for the 17 included studies in DBT arm, respectively, while, 83.7% (54.6–95.7), 71.3% (47.5–87.2), 2.71 (1.39–5.29), 0.20 (0.04–1.05), and 0.831 are the pooled sensitivity specificity, and and AUC for the five studies in the CBBCT arm, respectively. Conclusions: Our study demonstrates that DBT shows improved diagnostic performance over CBBCT regarding all estimated diagnostic parameters; with the statistical improvement in the AUC of DBT over CBBCT. The CBBCT might be a useful modality for breast cancer detection, thus we recommend more prospective studies on CBBCT application.

Assessment of Cone-Beam Breast Computed Tomography for Predicting Pathologic Response to Neoadjuvant Chemotherapy in Breast Cancer: A Prospective Study.

Background Response surveillance of neoadjuvant chemotherapy is needed to facilitate treatment decisions. We aimed to assess the imaging features of cone-beam breast computed tomography (CBBCT) for predicting the pathologic response of breast cancer after neoadjuvant chemotherapy. Methods This prospective study included 81 women with locally advanced breast cancer who underwent neoadjuvant chemotherapy from August 2017 to January 2021. All patients underwent CBBCT before treatment, and 55 and 65 patients underwent CT examinations during the midtreatment (3 cycles) and late-treatment phases (7 cycles), respectively. Clinical information and quantitative parameters such as the diameter, volume, surface area, and CT density were compared between pathologic responders and nonresponders using the T–test and the Mann–Whitney U test. The performance of meaningful parameters was evaluated with the receiver operating characteristic curve, sensitivity, and specificity. Results The quantitative results for the segmented volume, segmented surface area, segmented volume reduction, maximum enhancement ratio, wash-in rate and two-minute enhancement value in the mid- and late-treatment periods had predictive value for pathologic complete response. The area under the curve for the prediction model after multivariate regression analysis was 0.874. Conclusion After comparing the outcomes of each timepoint, mid- and late-treatment parameters can be used to predict pathologic outcome. The late-treatment parameters showed significant value with a predictive model.

Cone-beam breast CT using an offset detector: effect of detector offset and image reconstruction algorithm

Objective. A dedicated cone-beam breast computed tomography (BCT) using a high-resolution, low-noise detector operating in offset-detector geometry has been developed. This study investigates the effects of varying detector offsets and image reconstruction algorithms to determine the appropriate combination of detector offset and reconstruction algorithm. Approach. Projection datasets (300 projections in 360°) of 30 breasts containing calcified lesions that were acquired using a prototype cone-beam BCT system comprising a 40 × 30 cm flat-panel detector with 1024 × 768 detector pixels were reconstructed using Feldkamp–Davis–Kress (FDK) algorithm and served as the reference. The projection datasets were retrospectively truncated to emulate cone-beam datasets with sinograms of 768 768 and 640 768 detector pixels, corresponding to 5 cm and 7.5 cm lateral offsets, respectively. These datasets were reconstructed using the FDK algorithm with appropriate weights and an ASD-POCS-based Fast, total variation-Regularized, Iterative, Statistical reconstruction Technique (FRIST), resulting in a total of 4 offset-detector reconstructions (2 detector offsets × 2 reconstruction methods). Signal difference-to-noise ratio (SDNR), variance, and full-width at half-maximum (FWHM) of calcifications in two orthogonal directions were determined from all reconstructions. All quantitative measurements were performed on images in units of linear attenuation coefficient (1/cm). Results. The FWHM of calcifications did not differ (P > 0.262) among reconstruction algorithms and detector formats, implying comparable spatial resolution. For a chosen detector offset, the FRIST algorithm outperformed FDK in terms of variance and SDNR (P < 0.0001). For a given reconstruction method, the 5 cm offset provided better results. Significance. This study indicates the feasibility of using the compressed sensing-based, FRIST algorithm to reconstruct sinograms from offset-detectors. Among the reconstruction methods and detector offsets studied, FRIST reconstructions corresponding to a 30 cm × 30 cm with 5 cm lateral offset, achieved the best performance. A clinical prototype using such an offset geometry has been developed and installed for clinical trials.

Cone-Beam Breast Computed Tomography: Time for a New Paradigm in Breast Imaging.

It is time to reconsider how we image the breast. Although the breast is a 3D structure, we have traditionally used 2D mammography to perform screening and diagnostic imaging. Mammography has been continuously modified and improved, most recently with tomosynthesis and contrast mammography, but it is still using modifications of compression 2D mammography. It is time to consider 3D imaging for this 3D structure. Cone-beam breast computed tomography (CBBCT) is a revolutionary modality that will assist in overcoming the limitations of current imaging for dense breast tissue and overlapping structures. It also allows easy administration of contrast material for functional imaging. With a radiation dose on par with diagnostic mammography, rapid 10 s acquisition, no breast compression, and true high-resolution isotropic imaging, CBBCT has the potential to usher in a new era in breast imaging. These advantages could translate into lower morbidity and mortality from breast cancer.

Quantitative breast density measurement based on three-dimensional images: a study on cone-beam breast computed tomography

Breast density is an independent predictor of breast cancer risk. Quantitative volumetric breast density (QVBD) is expected to provide more information on the prediction of breast cancer risk. To evaluate the reliability of QVBD measurements based on cone-beam breast computed tomography (CBBCT) images. A total of 216 breasts were used to evaluate the stability of QVBD measurements based on CBBCT images and the correlations between this volumetric measurement and visual and area-based measurement methods. The intra- and inter-observer consistency of QVBD measurements were compared. Visual breast density (VBD) was evaluated with Breast Imaging Reporting and Data System (BI-RADS) standard on CBBCT images. The correlation between QVBD and VBD was evaluated by Spearman correlation coefficient. Receiver operating characteristic (ROC) curve was used to assess the sensitivity and specificity of the volumetric method in distinguishing dense and non-dense breasts. The correlation between QVBD and quantitative area-based breast density (QABD) was determined with Pearson correlation coefficient. Then, the breast volume measured with CBBCT images was compared with the breast specimen obtained during nipple-sparing mastectomy (NSM) by Pearson correlation coefficient and linear regression. Excellent intra- and inter-observer consistency was found from QVBD measurements. The volumetric method distinguished dense and non-dense breasts at a cutoff value of 9.5%, with 94.5% sensitivity and 77.1% specificity. Positive correlations were found between QVBD and QABD (r=0.890; P<0.001) and between the volume measured with CBBCT images and Archimedes method (r=0.969; P<0.001). CBBCT images can evaluate breast density reliably on a continuous scale.

Tumor-to-Gland Volume Ratio versus Tumor-to-Breast Ratio as Measured on CBBCT: Possible Predictors of Breast-Conserving Surgery.

BackgroundBreast-conserving surgery plus postoperative radiotherapy is the standard surgical treatment mode for early breast cancer. Currently, there are no clear predictive indicators to determine whether a patient can choose breast-conserving surgery, which mainly depends on the surgeon’s clinical experience and subjective judgment. Cone-beam breast computed tomography (CBBCT) reconstructs the breast 3D image from three mutually perpendicular angles, helping surgeons to locate and accurately measure the volume of the tumor, mammary gland, and breast. We used CBBCT to retrospectively measure the tumor-to-gland volume ratio and tumor-to-breast volume ratio in breast cancer cases. Then, we analyzed the correlation between the surgical methods and ratios in breast cancer patients.MethodsWe collected 100 patients undergoing breast-conserving surgery as the study group, and 100 patients undergoing mastectomy as the control group. All patients chose the surgical approach after comprehensive consideration of examination results and assessment of patient condition. Patients underwent CBBCT examination before surgery. We retrospectively measured the volume of tumor, mammary glands and breast, then calculated tumor-to-gland and tumor-to-breast volume ratios.ResultsTumor volume and the ratios of the two groups statistically differed (P < 0.001), while the mammary gland and breast volume did not (P > 0.05). The average tumor-to-gland volume ratio was 4.32% in the study group and 10.74% in the control group, and the average tumor-to-breast volume ratio was 0.74% in the study group and 1.36% in the control group. In breast-conserving surgery, the 95% reference range of tumor-to-gland ratio is (0, 12.90%), and the 95% reference range of tumor-to-breast ratio is (0, 2.17%).ConclusionThe tumor-to-gland volume ratio and tumor-to-breast volume ratio measured using CBBCT are correlated with the choice of surgical methods (breast-conserving surgery or mastectomy) for breast cancer patients. This can be used as possible predictor of breast-conserving surgery to help surgeons.

Radiation dosimetry of a clinical prototype dedicated cone-beam breast CT system with offset detector.

A clinical-prototype, dedicated, cone-beam breast computed tomography (CBBCT) system with offset detector is undergoing clinical evaluation at our institution. This study is to estimate the normalized glandular dose coefficients ( ) that provide air kerma-to-mean glandular dose conversion factors using Monte Carlo simulations. The clinical prototype CBBCT system uses 49kV x-ray spectrum with 1.39mm 1st half-value layer thickness. Monte Carlo simulations (GATE, version 8) were performed with semi-ellipsoidal, homogeneous breasts of various fibroglandular weight fractions ( , chest wall diameters ( cm), and chest wall to nipple length ( ), aligned with the axis of rotation (AOR) located at 65cm from the focal spot to determine the . Three geometries were considered - -cm detector with no offset that served as reference and corresponds to a clinical CBBCT system, -cm detector with 5cm offset, and a -cm detector with 10cm offset. For 5cm lateral offset, the ranged mGy/mGy and reduction in with respect to reference geometry was observed only for 18cm ( ) and 20cm ( ) diameter breasts. For the 10cm lateral offset, the ranged mGy/mGy and reduction in was observed for all breast diameters. The reduction in was , , , , and for 8, 10, 14, 18, and 20cm diameter breasts, respectively. For a given breast diameter, the reduction in with offset-detector geometries was not dependent on . Numerical fits of were generated for each geometry. The and the numerical fit, would be of benefit for current CBBCT systems using the reference geometry and for future generations using offset-detector geometry. There exists a potential for radiation dose reduction with offset-detector geometry, provided the same technique factors as the reference geometry are used, and the image quality is clinically acceptable.

Sparse-view, short-scan, dedicated cone-beam breast computed tomography: image quality assessment

The purpose of this study is to quantify the impact of sparse-view acquisition in short-scan trajectories, compared to 360-degrees full-scan acquisition, on image quality measures in dedicated cone-beam breast computed tomography (BCT). Projection data from 30 full-scan (360-degrees; 300 views) BCT exams with calcified lesions were selected from an existing clinical research database. Feldkamp-Davis-Kress (FDK) reconstruction of the full-scan data served as the reference. Projection data corresponding to two short-scan trajectories, 204 and 270-degrees, which correspond to the minimum and maximum angular range achievable in a cone-beam BCT system were selected. Projection data were retrospectively sampled to provide 225, 180, and 168 views for 270-degrees short-scan, and 170 views for 204-degrees short-scan. Short-scans with 180 and 168 views in 270-degrees used non-uniform angular sampling. A fast, iterative, total variation-regularized, statistical reconstruction technique (FIRST) was used for short-scan image reconstruction. Image quality was quantified by variance, signal-difference to noise ratio (SDNR) between adipose and fibroglandular tissues, full-width at half-maximum (FWHM) of calcifications in two orthogonal directions, as well as, bias and root-mean-squared-error (RMSE) computed with respect to the reference full-scan FDK reconstruction. The median values of bias (8.6 × 10−4–10.3 × 10−4 cm−1) and RMSE (6.8 × 10−6–9.8 × 10−6 cm−1) in the short-scan reconstructions, computed with the full-scan FDK as the reference were close to, but not zero (P < 0.0001, one-sample median test). The FWHM of the calcifications in the short-scan reconstructions did not differ significantly from the reference FDK reconstruction (P > 0.118), except along the superior-inferior direction for the short-scan reconstruction with 168 views in 270-degrees (P = 0.046). The variance and SDNR from short-scan reconstructions were significantly improved compared to the full-scan FDK reconstruction (P < 0.0001). This study demonstrates the feasibility of the short-scan, sparse-view, compressed sensing-based iterative reconstruction. This study indicates that shorter scan times and reduced radiation dose without sacrificing image quality are potentially feasible.

Comparison of comfort between cone beam breast computed tomography and digital mammography

PurposeTo compare the comfort levels of cone beam breast computed tomography (CBBCT) and digital mammography. Materials and methodsOn 409 patients, CBBCT was performed within 1 week after conventional mammography. Patients evaluated their comfort by using an 11-point numerical rating scale (NRS-11) after completing the two examinations. The lower the score was, the more comfortable the examination modality was. The data was divided into different groups according to CBBCT scan mode (non-contrast mode, contrast-enhanced mode), age (≤44, 45∼59 and ≥60), body mass index (BMI) (<18.5 kg/m2, 18.5∼23.9 kg/m2, 24∼27.9 kg/m2 and ≥28 kg/m2), and breast density (fatty-breast, dense-breast) to evaluate the performance of CBBCT comfort in different groups and to analyse the influencing factor of patient comfort. The paired rank sum test was used to compare the comfort between CBBCT and mammography. ResultsOverall, the comfort of CBBCT was better than mammography (P < 0.05). CBBCT was more comfortable than mammography in both non-contrast and contrast-enhanced groups (P < 0.05). CBBCT was more comfortable than mammography in the ≤44, 45∼59 age groups (P < 0.05). There was no significant difference in the ≥60 age group (P = 0.5433). CBBCT was more comfortable than mammography in the BMI groups of 18.5∼23.9 kg/m2, 24∼27.9 kg/m2and ≥28 kg/m2 (P < 0.05). There was no significant difference in the <18.5 kg/m2 group (P = 0.43). CBBCT was more comfortable than mammography in both the fatty-breast and dense-breast groups (P < 0.05). ConclusionThe comfort of CBBCT was better than mammography.