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

Abstract

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.

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

“…For the system used to acquire the clinical datasets in this study, the estimated MGD reduction with a shortscan trajectory inferior to the breast and spanning 205 • is 52.2%. If a short-scan trajectory spanning 270 • as suggested by a recent study 32 is considered, then the estimated MGD reduction is 35.7%.…”

“…The motivation for this study is derived from our ongoing research on the potential of short-scan trajectory in CBBCT. Short-scan acquisitions with appropriate image reconstruction algorithms [26][27][28][29][30][31][32] are known to be one of the effective methods to reduce radiation dose. For such short-scan acquisition in CBBCT, it is important to determine the trajectory of the x-ray source movement along an arc in terms of the start and stop angles of the arc, with an objective of minimizing the radiation dose.…”

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

“…Since visualization of microcalcifications at MGD suitable for screening (Lindfors et al 2008) is the main challenge, 30 cases with calcifications were selected for this study. The same set of 30 cases was also used in a study investigating short-scan, sparse-view dedicated cone-beam BCT, and hence the subject characteristics summarized in table 1 of that prior study (Tseng et al 2020a) are identical to this study. Briefly, the median (interquartile range) for age, diameter at chest-wall, fibroglandular weight fraction, and the MGD for this cohort were 51 (46-57) years, 13.5 (12-15.1) cm, 11.7 (7.3-19.5) %, and 11.4 (9.9-14.4) mGy, respectively.…”

“…For full-scan acquisition, the evaluation of image reconstruction techniques using compressed sensing in conjunction with offset geometry is important in reducing the mean glandular dose (MGD) from breast CT (Tseng et al 2021) so that it is comparable to a standard 2-view screening mammography exam. An alternative is to use short-scan acquisition (Tseng et al 2020a). Reducing the radiation dose is essential for translating breast CT for breast cancer screening.…”

Angular normalized glandular dose coefficient in breast CT: clinical data study

“…To our best knowledge, studies in literature only considered 𝐷𝑔𝑁 𝐶𝑇 , but none have considered the variation of the 𝐷𝑔𝑁 𝐶𝑇 with the projection angles, i.e., angular 𝐷𝑔𝑁 𝐶𝑇 . We are particularly interested in 𝐷𝑔𝑁 𝐶𝑇 because we have developed feasible image reconstruction algorithms for short-scan and sparse-view acquisitions [12], [13], and we would like to understand which angular range should be used for short-scan acquisition to reduce the radiation to the breast either for prone or upright patient-position CBBCT systems. A cohort of 75 CBBCT datasets from a research database of subjects who had participated in a prior IRB-approved clinical trial was used in this study.…”