System calibration for quantitative contrast-enhanced digital breast tomosynthesis (CEDBT)

Abstract

In contrast-enhanced (CE) breast imaging, lesion contrast agent content may be diagnostic, relating to vascularization and tumour angiogenesis. However, factors in CE digital breast tomosynthesis (DBT) such as incomplete angular sampling, beam hardening and scatter can confound quantitative measurement. We propose system calibration to improve CEDBT quantitative potential. Fifteen projection images of an iodine calibration phantom, with various breast-equivalent compositions, thicknesses and lesion locations, were acquired over 40°, and reconstructed using SART. A separate breast-equivalent phantom with iodinated spherical lesions was imaged to test quantification accuracy. Excellent linearity between voxel signal and iodine concentration was achieved in the calibration data. In test phantom cases, lesion signal faithfully represented the true iodine concentration, but with wide confidence intervals for small lesions. While promising, it remains to be determined whether the iodine quantification accuracy is sufficient for lesion differentiation, and whether lesion shape, position, and non-uniform breast tissue would impair this estimation.