Fractional Fourier transform as a signal processing tool: An overview of recent developments

Objective
To assess the diagnostic accuracy of Dual-Energy Contrast-Enhanced Digital Mammography (CEDM) as an adjunct to mammography (MX) versus MX alone and versus mammography plus ultrasound (US).

/pdf/dual-energy-contrast-enhanced-digital-mammography-initial-1sfha1uza0.pdf

Dual-energy contrast-enhanced digital mammography: initial clinical results

Many important post-acquisition aspects of breast tomosynthesis imaging can impact its clinical performance. Chief among them is the reconstruction algorithm that generates the representation of the three-dimensional breast volume from the acquired projections. But even after reconstruction, additional processes, such as artifact reduction algorithms, computer aided detection and diagnosis, among others, can also impact the performance of breast tomosynthesis in the clinical realm. In this two part paper, a review of breast tomosynthesis research is performed, with an emphasis on its medical physics aspects. In the companion paper, the first part of this review, the research performed relevant to the image acquisition process is examined. This second part will review the research on the post-acquisition aspects, including reconstruction, image processing, and analysis, as well as the advanced applications being investigated for breast tomosynthesis.

/pdf/a-review-of-breast-tomosynthesis-part-ii-image-2wlpx9aiz2.pdf

A review of breast tomosynthesis. Part II. Image reconstruction, processing and analysis, and advanced applications

In recent years the structural similarity index has become an accepted standard among image quality metrics. Made up of three components, this technique assesses the visual impact of changes in image luminance, contrast, and structure. Applications of the index include image enhancement, video quality monitoring, and image encoding. As its status continues to rise, however, so do questions about its performance. In this paper, it is shown, both empirically and analytically, that the index is directly related to the conventional, and often unreliable, mean squared error. In the first evaluation, the two metrics are statistically compared with one another. Then, in the second, a pair of functions that algebraically connects the two is derived. These results suggest a much closer relationship between the structural similarity index and mean squared error.

A comprehensive assessment of the structural similarity index

The purpose of this study was to compare the diagnostic accuracy of dual-energy contrast-enhanced digital mammography (CEDM) as an adjunct to mammography (MX) ± ultrasonography (US) with the diagnostic accuracy of MX ± US alone. One hundred ten consenting women with 148 breast lesions (84 malignant, 64 benign) underwent two-view dual-energy CEDM in addition to MX and US using a specially modified digital mammography system (Senographe DS, GE Healthcare). Reference standard was histology for 138 lesions and follow-up for 12 lesions. Six radiologists from 4 institutions interpreted the images using high-resolution softcopy workstations. Confidence of presence (5-point scale), probability of cancer (7-point scale), and BI-RADS scores were evaluated for each finding. Sensitivity, specificity and ROC curve areas were estimated for each reader and overall. Visibility of findings on MX ± CEDM and MX ± US was evaluated with a Likert scale. The average per-lesion sensitivity across all readers was significantly higher for MX ± US ± CEDM than for MX ± US (0.78 vs. 0.71 using BIRADS, p = 0.006). All readers improved their clinical performance and the average area under the ROC curve was significantly superior for MX ± US ± CEDM than for MX ± US ((0.87 vs 0.83, p = 0.045). Finding visibility was similar or better on MX ± CEDM than MX ± US in 80% of cases. Dual-energy contrast-enhanced digital mammography as an adjunct to MX ± US improves diagnostic accuracy compared to MX ± US alone. Addition of iodinated contrast agent to MX facilitates the visualization of breast lesions.

https://cdr.lib.unc.edu/downloads/jm214r42w

Dual-energy contrast-enhanced digital mammography: initial clinical results of a multireader, multicase study

In this study, we propose a novel approach to dual-energy contrast-enhanced digital mammography, with the development of a dual-energy recombination algorithm based on an image chain model and the determination of the associated optimal low and high-energy techniques. Our method produces clutter-free iodine-equivalent images and includes thickness correction near the breast border. After the algorithm description, the optimal low and high-energy acquisition techniques are determined to obtain a compromise between image quality and glandular dose. The low and high-energy techniques were chosen to minimize the glandular dose for a target Signal Difference to Noise Ratio (SDNR) in the dual-energy recombined image. The theoretical derivation of the iodine SDNR in the recombined image allowed the prediction of the optimal low and high-energy techniques. Depending on the breast thickness and glandular percentage, the optimal low-energy kVp and mAs ranged from 24kVp (Mo/Mo or Mo/Rh) to 35kVp (Rh/Rh), and from 60 to 90mAs respectively, and the high-energy kVp and mAs ranged from 40kVp to 47kVp (Mo/Cu), and from 80mAs to 290mAs. We proved the better performance of our algorithm compared to the classic weighted logarithmic subtraction method in terms of patient dose and also in terms of texture cancelation, through the use of artificial textured images. Values of iodine contrast measured on phantom were close to the expected iodine thickness. Good correlation was found between the measured and theoretical iodine SDNR in the dual-energy images, which validates our theoretical optimization of the acquisition techniques.

Dual-energy contrast enhanced digital mammography using a new approach for breast tissue canceling

This paper demonstrates the usefulness of spatial/spatial-frequency representations in image quality assessment by introducing a new image dissimilarity measure based on 2D Wigner-Ville distribution (WVD). The properties of 2D WVD are shortly reviewed, and the important issue of choosing the analytic image is emphasized. The WVD-based measure is shown to be correlated with subjective human evaluation, which is the premise towards an image quality assessor developed on this principle.

/pdf/image-quality-assessment-using-the-joint-spatial-spatial-incyv7zsti.pdf

Image quality assessment using the joint spatial/spatial-frequency representation

A method for performing a computer aided detection (CAD) analysis of images acquired from a multiple projection X-ray system is provided. The method comprises accessing the projection images from the multiple projection X-ray system and applying a plurality of reconstruction algorithms on the projection images to generate a plurality of reconstructed images. Then, the method comprises applying a CAD algorithm to the plurality of reconstructed images.

Tomographic computer aided diagnosis (CAD) with multiple reconstructions

In this paper, we present the development of dual-energy Contrast-Enhanced Digital Breast Tomosynthesis
(CEDBT). A method to produce background clutter-free slices from a set of low and high-energy projections
is introduced, along with a scheme for the determination of the optimal low and high-energy techniques. Our
approach consists of a dual-energy recombination of the projections, with an algorithm that has proven its performance
in Contrast-Enhanced Digital Mammography 1 (CEDM), followed by an iterative volume reconstruction.
The aim is to eliminate the anatomical background clutter and to reconstruct slices where the gray level is
proportional to the local iodine volumetric concentration. Optimization of the low and high-energy techniques
is performed by minimizing the total glandular dose to reach a target iodine Signal Difference to Noise Ratio
(SDNR) in the slices. In this study, we proved that this optimization could be done on the projections, by
consideration of the SDNR in the projections instead of the SDNR in the slices, and verified this with phantom
measurements. We also discuss some limitations of dual-energy CEDBT, due to the restricted angular range
for the projection views, and to the presence of scattered radiation. Experiments on textured phantoms with
iodine inserts were conducted to assess the performance of dual-energy CEDBT. Texture contrast was nearly
completely removed and the iodine signal was enhanced in the slices.

Dual-energy contrast enhanced digital breast tomosynthesis: concept, method, and evaluation on phantoms

Dual-Energy Contrast Enhanced Digital Breast Tomosynthesis (DE CEDBT) is a promising technique for breast
cancer detection, which combines the strengths of functional and 3D imaging. In the present study, we first
focused on the optimization of the acquisition parameters for the low and high-energy projections, which leads
to a trade-off between image quality in the recombined slices and the Average Glandular Dose (AGD) delivered
to the patient. Optimized parameters were found and experimentally validated on phantom images. Then, we
addressed the problem of iodine quantification in the recombined slices. In DE CEDBT, iodine quantification is
limited by the z-resolution, due to the restricted angle acquisition inherent to tomosynthesis. We evaluated the
lesion thickness above which determination of iodine volumetric concentration is possible. For lesions below this
thickness, estimation of iodine concentration is possible if a priori information or a model on the shape of the
lesion is available. Iodine quantification for lesions located near the breast boundary is also challenging, due to
scatter border effects and variation of the breast thickness in this region. A scatter correction algorithm based
on a deconvolution scheme and a thickness compensation algorithm were applied on the low and high-energy
projections. Corrected images showed a more accurate quantification of iodine.

/pdf/optimization-of-beam-parameters-and-iodine-quantification-in-4e0800fft8.pdf

Razvan Iordache

Papers

Dual-energy contrast enhanced digital mammography using a new approach for breast tissue canceling

Image quality assessment using the joint spatial/spatial-frequency representation

Tomographic computer aided diagnosis (CAD) with multiple reconstructions

Dual-energy contrast enhanced digital breast tomosynthesis: concept, method, and evaluation on phantoms

Optimization of beam parameters and iodine quantification in dual-energy contrast enhanced digital breast tomosynthesis