Quantitative characterization of breast tissues with dedicated CT imaging

Abstract

A quantitative characterization of the soft tissues composing the human breast is achieved by means of a monochromatic CT phase-contrast imaging system, through accurate measurements of their attenuation coefficients within the energy range of interest for breast CT clinical examinations. Quantitative measurements of linear attenuation coefficients are performed on tomographic reconstructions of surgical samples, using monochromatic X-ray beams from a synchrotron source and a free space propagation setup. An online calibration is performed on the obtained reconstructions, in order to reassess the validity of the standard calibration procedure of the CT scanner. Three types of healthy tissues (adipose, glandular, and skin) and malignant tumors, when present, are considered from each sample. The measured attenuation coefficients are in very good agreement with the outcomes of similar studies available in the literature, although they span an energy range that was mostly neglected in the previous studies. No globally significant differences are observed between healthy and malignant dense tissues, although the number of considered samples does not appear sufficient to address the issue of a quantitative differentiation of tumors. The study assesses the viability of the proposed methodology for the measurement of linear attenuation coefficients, and provides a denser sampling of attenuation data in the energy range useful to breast CT.

Experimental optimization of the energy for breast-CT with synchrotron radiation

“…In terms of linear attenuation coefficients of glandular and adipose tissues, (Piai et al 45 ) showed a substantial agreement of experimental results with previously published data 46 , 47 . For this reason, the chemical compositions reported in (Hammerstein et al 31 and Boone and Chavez 48 ) were used for glandular and adipose tissues in actual breast samples, as done in our previous paper 37 .…”

“…Breast samples T2 and T3 have been already presented in (Piai et al 45 ), as Sample 7 and Sample 4, respectively. Representative slices of the tomographic reconstruction of three samples are reported in Fig.…”

Recent advances in X-ray imaging of breast tissue: From two- to three-dimensional imaging

“…But one must consider that this energy is just optimized for this specific beamline and geometry and can be further influenced by a real detector (due to different energy responses). In addition, the composition of different breast tissues (adipose, glandular, tumor, skin) has been evaluated at the SYRMEP beamline in terms of estimating the linear attenuation coefficient with totally seven samples in an BCT-interesting energy range (26-38 keV) [72]. The results agree with the already existing literature values.…”

“…Another technique that has evolved in recent years is propagationbased rather than grating-based phase-contrast imaging for computed tomography of the female breast, as this approach benefits from the fact that there are no gratings in the beam path that negatively affects the MGD. Several advances were achieved and different aspects investigated in the latest time which have been performed at the SYRMEP beamline at the Elettra Synchrotron in Trieste [71][72][73][74][75][76][77][78][79]. After an initial feasibility study [79], first studies published in 2018 present the first full-volume 6.…”

In Silico Phase-Contrast X-Ray Imaging of Anthropomorphic Voxel-Based Phantoms

“…The calcifications were simulated as calcium oxalate (CaC 2 O 4 ) with a density of 2.12 g/cm 3 . The lesions in the breast phantom were simulated as glandular tissue with ∼6% higher density, 1.1 g/cm 3 instead of nominal value of 1.035 g/cm 3 , which is within values previously reported [43], [44]. Figure 6 shows simulated mammograms corresponding to a screening scenario (M = 1) generated through both MC and WP approaches as described in Sec.…”