The detection of cancerous mass lesions using digital breast tomosynthesis (DBT) has been shown to be limited in patients with dense breasts. Detection may potentially be improved by increasing the DBT angular range (AR), which reduces breast structural noise and increases object contrast in the reconstructed slice. We investigate the impact of DBT AR on the detection of masses in a simulation study using a cascaded linear system model (CLSM) for DBT. We compare the mass conspicuity between wide- and narrow-AR DBT system in a clinical pilot study. The simulation results show reduced in-plane breast structural noise and increased in-plane detectability of masses with increasing AR. The clinical results show that masses are more conspicuous in wide-AR DBT than narrow-AR DBT. Our study indicates that the detection of mass lesions in dense breasts can be improved by increasing DBT AR.
Contrast-Enhanced Digital Breast Tomosynthesis (CEDBT) provides a three-dimensional (3D) contrast-enhancement map with co-registered anatomical information from low-energy DBT. It combines the benefits from Contrast-Enhanced Digital Mammography (CEDM) and Digital Breast Tomosynthesis (DBT), and may improve breast cancer detection and assessment of lesion morphology. We investigate the efficacy of CEDBT in the assessment of lesion contrast enhancement and margin identification, and evaluate the dose efficiency. We generate synthetic CEDM images from CEDBT data, similar to synthesis of 2D mammograms from DBT data, which may facilitate overall lesion assessment without additional radiation dose. Preliminary results from a patient study show that CEDBT depicts lesion margins better compared to CEDM, while the contrast-enhancement level for in-plane slice is not as high as in CEDM. CEDBT delivers less radiation dose compared to CEDM + DBT. Synthetic CEDM is able to provide lesion contrast-enhancement level comparable to CEDM.
Breast compression is utilized in mammography to improve image quality and reduce radiation dose. Lesion conspicuity is improved by reducing scatter effects on contrast and by reducing the superposition of tissue structures. However, patient discomfort due to breast compression has been cited as a potential cause of noncompliance with recommended screening practices. Further, compression may also occlude blood flow in the breast, complicating imaging with intravenous contrast agents and preventing accurate quantification of contrast enhancement and kinetics. Previous studies have investigated reducing breast compression in planar mammography and digital breast tomosynthesis (DBT), though this typically comes at the expense of degradation in image quality or increase in mean glandular dose (MGD). We propose to optimize the image acquisition technique for reduced compression in DBT without compromising image quality or increasing MGD. A zero-frequency signal-difference-to-noise ratio model is employed to investigate the relationship between tube potential, SDNR and MGD. Phantom and patient images are acquired on a prototype DBT system using the optimized imaging parameters and are assessed for image quality and lesion conspicuity. A preliminary assessment of patient motion during DBT with minimal compression is presented.
We have previously proposed SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout), a
novel detector concept with potentially superior spatial resolution and low-dose performance compared with existing
flat-panel imagers. The detector comprises a scintillator that is optically coupled to an amorphous selenium
photoconductor operated with avalanche gain, known as high-gain avalanche rushing photoconductor (HARP). High
resolution electron beam readout is achieved using a field emitter array (FEA). This combination of avalanche gain,
allowing for very low-dose imaging, and electron emitter readout, providing high spatial resolution, offers potentially
superior image quality compared with existing flat-panel imagers, with specific applications to fluoroscopy and breast
imaging. Through the present collaboration, a prototype HARP sensor with integrated electrostatic focusing and nano-
Spindt FEA readout technology has been fabricated. The integrated electron-optic focusing approach is more suitable for
fabricating large-area detectors. We investigate the dependence of spatial resolution on sensor structure and operating
conditions, and compare the performance of electrostatic focusing with previous technologies. Our results show a clear
dependence of spatial resolution on electrostatic focusing potential, with performance approaching that of the previous
design with external mesh-electrode. Further, temporal performance (lag) of the detector is evaluated and the results
show that the integrated electrostatic focusing design exhibits comparable or better performance compared with the
mesh-electrode design. This study represents the first technical evaluation and characterization of the SAPHIRE concept
with integrated electrostatic focusing.
Contrast enhanced (CE) breast imaging has been proposed as a method to increase the sensitivity and specificity of
breast cancer detection. Because malignant lesions often exhibit angiogenesis, the uptake of radio-opaque contrast agents (e.g. iodine) results in increased attenuation compared to the background tissue. Both planar CE digital mammography (CE-DM) and digital breast tomosynthesis (CE-DBT) have been proposed, using temporal or dual energy (DE) subtraction to remove tissue backgrounds. In the current study, we apply a cascaded linear systems model approach to analyze CE techniques with DE subtraction for designing a diagnostic imaging study, including the effects of contrast dynamics. We apply the model for both CE-DM and CE-DBT to calculate the ideal observer signal-to-noise ratio (SNR)
for the detection of I contrast objects of different sizes and concentrations. The calculation of this figure-of-merit (FOM) was be used to optimize CE clinical imaging protocols.