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FIGS 5a, 5b, 5c


to perform standard mammograms and FFDM/DBT real time selection with breast compression in place. Instead, we can find a great variability


5a 5b 5c IMAGE 1, 2, 3


in the acquisitions number take-over (between 13 and 25) and the acquisition angle (between 15° and 50°), along with significant features in image quality that in DBT depends on the dose and the number of projections and acquisition angle as well the number of exposures. So, if a narrow angle with little exposure allows a fast but low-resolution 3D acquisition (figure 5a), a wide angle with so many exposures provides a good resolution 3D (figure 5b). An interesting alternative is represented


1


by variable geometry (V-DBT), which offers the highest 3D resolution at maximum speed acquisition due to a non-uniform sampling. In V-DBT 13 images are taken through the 40° tube oscillation movement, the central one with 50% of the total dose delivered (the same as that required for a single mammography projection), and the remaining 50% unevenly split among the twelve remaining acquisitions (figure 5c). Reconstruction algorithm in V-DBT system takes full advantage of any information provided in the 0° projection, which is basically a standard mammogram characterized by high contrast, which also provides valuable information for the microcalcifications visualization and their identification by 3D CAD, not yet available, but certainly among the future developments related to DBT.


2 3


CONCLUSION In conclusion, DBT is definitely able to improve dense breast imaging using a two- projection mammography dose, preserving high spatial resolution and quick workflow typical of FFDM.DBT can improve specificity in screening ruling out overlapping structures, facilitating such small lesions identification. Iodinated contrast media may add more detailed information about blood supply dynamics of previously identified lesions, even compared to those obtained with CEDM - Contrast-Enhanced Digital Mammography. ■


ID


 Image 1: A 1 mm slices sequence  Image 2: A mass with undefined edges that reveals spiculated in DBT (right) is recognizable with difficulty in FFDM image (left). DBT allows the identificationa greater number of lesions, a better analysis of masses shape and architectural distortion extension.  Image 3: Comparative chart of currently marketed DBT systems constructive and performance characteristics


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 REFERENCES References available on request (magazine@informa.com)


 IMAGES Images courtesy of IMS Italy


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