Lint: digital-breast-tomosynthesis

"Digital breast tomosynthesis (DBT) is an imaging technique that allows a volumetric reconstruction of the whole breast from a finite number of low-dose two-dimensional projections obtained by different X-ray tube angles, with a geometric principle very similar to that applied in the stratigraphic technique."

"Although direct digital mammography (FFDM - full field digital mammography) has improved the sensitivity of the method, especially in dense breasts, the number of false negatives (FN) is still high, largely due to the presence of dense tissue that may affect lesions conspicuity: the mammogram is, in fact, a ”summation image" that displays on a single plane a more or less visible representation of any structure crossed by the X-ray beam between input and output surfaces."

"In DBT the X-ray tube makes an arc, during which a series of images are acquired, each of which is delivered a dose equal to a fraction of that provided in a standard mammogram. During the acquisition, any detector element receives in time sequence-related information on each object volume element. The set of digital projections thus contains complete structural information on all the object layers in the form of raw data. These are sent to a computer, whereby appropriate reconstruction algorithms will reconstruct the order and the correct summation of the projection values which allows, as a final result, to obtain sections comparable to those of conventional tomography, but exempt from the critical previously explained."

"Although direct digital mammography (FFDM - full field digital mammography) has improved the sensitivity of the method, especially in dense breasts, the number of false negatives (FN) is still high, largely due to the presence of dense tissue that may affect lesions conspicuity: the mammogram is, in fact, a ”summation image" that displays on a single plane a more or less visible representation of any structure crossed by the X-ray beam between input and output surfaces."

"Reconstruction algorithms used in the first generation of devices (including FBP-Filtered Back Projection algorithm, ideal for 360° CT acquisitions reconstruction, but not optimal in DBT reconstruction, in which it generates noise and artifacts) were today abandoned for iterative algorithms, such as the SART -Simultaneous Algebraic Reconstruction Technique, and the MLEM - Maximum Likelihood Expectation Maximisation, which can improve imaging quality through the final reduction of streaking artifacts, as well the increasing of contrast-to-noise ratio, thus improving the visibility of microcalcifications and skin edge."

"Reconstruction algorithms used in the first generation of devices (including FBP-Filtered Back Projection algorithm, ideal for 360° CT acquisitions reconstruction, but not optimal in DBT reconstruction, in which it generates noise and artifacts) were today abandoned for iterative algorithms, such as the SART -Simultaneous Algebraic Reconstruction Technique, and the MLEM - Maximum Likelihood Expectation Maximisation, which can improve imaging quality through the final reduction of streaking artifacts, as well the increasing of contrast-to-noise ratio, thus improving the visibility of microcalcifications and skin edge."

"According to early trial data, DBT is designed to offer the conspicuity of a higher percentage of breast cancers than conventional mammography, reducing false negative (FN) percentage at an estimated value of around 15%. Studies indicate about 30% increased DBT sensitivity and specificity compared to FFDM with a recalls reduction in screening by approximately 40%."

"It’s still ongoing a study comparing the clinical performance of FFDM in two projections (CC + MLO) and those of DBT in a single projection (MLO) in compliance with dose constraint. Until it will be demonstrated at least the clinical “non-inferiority” of DBT compared to FFDM, it is not reasonable a dose increasing in DBT. For this reason, the dose is restrained so as not to exceed the dose of a two-projections FFDM.Features common to every DBT systems are the execution mode (MLO projection), acquisition time (10-20 sec) and reconstruction time (between 40 and 180 sec), slices thickness (1 mm), display mode (single slice, or slab cine loop), chance to perform standard mammograms and FFDM/DBT real-time selection with breast compression in place.We can find, instead, great variability in the acquisitions number take-over (between 13 and 25) and the acquisition angle (between 15 ° and 50 °), 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, a wide-angle with so many exposures provide a good resolution 3D but at a low-speed acquisition with consequent means of motion artifacts and quality deterioration of reconstructed images."

"It’s still ongoing a study comparing the clinical performance of FFDM in two projections (CC + MLO) and those of DBT in a single projection (MLO) in compliance with dose constraint. Until it will be demonstrated at least the clinical “non-inferiority” of DBT compared to FFDM, it is not reasonable a dose increasing in DBT. For this reason, the dose is restrained so as not to exceed the dose of a two-projections FFDM.Features common to every DBT systems are the execution mode (MLO projection), acquisition time (10-20 sec) and reconstruction time (between 40 and 180 sec), slices thickness (1 mm), display mode (single slice, or slab cine loop), chance to perform standard mammograms and FFDM/DBT real-time selection with breast compression in place.We can find, instead, great variability in the acquisitions number take-over (between 13 and 25) and the acquisition angle (between 15 ° and 50 °), 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, a wide-angle with so many exposures provide a good resolution 3D but at a low-speed acquisition with consequent means of motion artifacts and quality deterioration of reconstructed images."

"It’s still ongoing a study comparing the clinical performance of FFDM in two projections (CC + MLO) and those of DBT in a single projection (MLO) in compliance with dose constraint. Until it will be demonstrated at least the clinical “non-inferiority” of DBT compared to FFDM, it is not reasonable a dose increasing in DBT. For this reason, the dose is restrained so as not to exceed the dose of a two-projections FFDM.Features common to every DBT systems are the execution mode (MLO projection), acquisition time (10-20 sec) and reconstruction time (between 40 and 180 sec), slices thickness (1 mm), display mode (single slice, or slab cine loop), chance to perform standard mammograms and FFDM/DBT real-time selection with breast compression in place.We can find, instead, great variability in the acquisitions number take-over (between 13 and 25) and the acquisition angle (between 15 ° and 50 °), 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, a wide-angle with so many exposures provide a good resolution 3D but at a low-speed acquisition with consequent means of motion artifacts and quality deterioration of reconstructed images."

"It’s still ongoing a study comparing the clinical performance of FFDM in two projections (CC + MLO) and those of DBT in a single projection (MLO) in compliance with dose constraint. Until it will be demonstrated at least the clinical “non-inferiority” of DBT compared to FFDM, it is not reasonable a dose increasing in DBT. For this reason, the dose is restrained so as not to exceed the dose of a two-projections FFDM.Features common to every DBT systems are the execution mode (MLO projection), acquisition time (10-20 sec) and reconstruction time (between 40 and 180 sec), slices thickness (1 mm), display mode (single slice, or slab cine loop), chance to perform standard mammograms and FFDM/DBT real-time selection with breast compression in place.We can find, instead, great variability in the acquisitions number take-over (between 13 and 25) and the acquisition angle (between 15 ° and 50 °), 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, a wide-angle with so many exposures provide a good resolution 3D but at a low-speed acquisition with consequent means of motion artifacts and quality deterioration of reconstructed images."

"In conclusion, DBT is definitely able to improve dense breasts imaging using a two- projections mammography dose, preserving high spatial resolution and quick workflow typical of FFDM. DBT can improve specificity in screening ruling out overlapping structures, facilitating so small lesions identification."

"The phenomena of summation and subtraction, potentially responsible for the production of false-positive findings (FP) and for masking of true positive findings (TP), led in 1930 Alessandro Vallebona to create and implement the “stratigraphy” (hereinafter referred to as “tomography”), that is a complementary radiodiagnostic technique aimed at realising of analytical images, namely representative just of the structures including in the pre-selected layers of the concerned region. This technique was not without its drawbacks, which include:"

"Reconstruction algorithms used in the first generation of devices (including FBP-Filtered Back Projection algorithm, ideal for 360° CT acquisitions reconstruction, but not optimal in DBT reconstruction, in which it generates noise and artifacts) were today abandoned for iterative algorithms, such as the SART -Simultaneous Algebraic Reconstruction Technique, and the MLEM - Maximum Likelihood Expectation Maximisation, which can improve imaging quality through the final reduction of streaking artifacts, as well the increasing of contrast-to-noise ratio, thus improving the visibility of microcalcifications and skin edge."

"History"