Ultrasound imaging is a commonly used modality for breast cancer detection and diagnosis. In this review, we summarize ultrasound imaging technologies and their clinical applications for the management of breast cancer patients. The technologies include ultrasound elastography, contrast-enhanced ultrasound, 3-D ultrasound, automatic breast ultrasound and computer-aided detection of breast ultrasound. We summarize the study results seen in the literature and discuss their future directions. We also provide a review of ultrasound-guided, breast biopsy and the fusion of ultrasound with other imaging modalities, especially magnetic resonance imaging (MRI). For comparison, we also discuss the diagnostic performance of mammography, MRI, positron emission tomography and computed tomography for breast cancer diagnosis at the end of this review. New ultrasound imaging techniques, ultrasound-guided biopsy and the fusion of ultrasound with other modalities provide important tools for the management of breast patients.

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Ultrasound Imaging Technologies for Breast Cancer Detection and Management: A Review

Mammography, today’s standard imaging approach, has deficits with respect to the superimposition of anatomical structures. Dedicated CT of the breast so far indicated that it can provide superior soft-tissue imaging, but that it still has significant limitations with respect to spatial resolution and dose. We have assessed novel dedicated breast CT technology. Based on simulations and measurements we developed novel technology which uses direct-conversion CdTe material and photon-counting electronics with 100 μm detector element size for close to 100% dose efficiency. We assessed the potential for the imaging of microcalcifications of 100 to 200 μm diameter and soft-tissue lesions of 1 to 5 mm diameter by simulations at dose levels between 1 and 6 mGy. Microcalcifications of 150 μm and soft-tissue lesions of 2 mm diameter were found to be clearly detectable at an average glandular dose of 3 mGy. Separate displays are required for high-resolution microcalcification and for low-resolution soft-tissue analysis. Total CT data acquisition time will be below 10 s. Dedicated breast CT may eventually provide comprehensive diagnostic assessment of microcalcifications and soft-tissue structures at dose levels equivalent to or below those of two-view screening mammography.

High-resolution spiral CT of the breast at very low dose: concept and feasibility considerations.

Purpose: Design and optimization of medical imaging systems benefit from accurate theoretical modeling that identifies the physical factors governing image quality, particularly in the early stages of system development. This work extends Fourier metrics of imaging performance and detectability index (d′) to tomosynthesis and cone-beam CT (CBCT) and investigates the extent to which d′ is a valid descriptor of task-based imaging performance as assessed by human observers.

Methods: The detectability index for tasks presented in 2D slices (dslice′) was derived from 3D cascaded systems analysis of tomosynthesis and CBCT. Anatomical background noise measured in a physical phantom presenting power-law spectral density was incorporated in the “generalized” noise-equivalent quanta. Theoretical calculations of dslice′ were performed as a function of total angular extent (θtot) of source-detector orbit ranging 10°–360° under two acquisition schemes: (i) Constant angular separation between projections (constant-Δθ), giving variable number of projections (Nproj) and dose vs θtot and (ii) constant number of projections (constant-Nproj), giving constant dose (but variable angular sampling) with θtot. Five simple observer models were investigated: Prewhitening (PW), prewhitening with eye filter and internal noise (PWEi), nonprewhitening (NPW), nonprewhitening with eye filter (NPWE), and nonprewhitening with eye filter and internal noise (NPWEi). Human observer performance was measured in 9AFC tests for five simple imaging tasks presented within uniform and power-law clutter backgrounds. Measurements (from 9AFC tests) and theoretical calculations (from cascaded systems analysis of dslice′) were compared in terms of area under the ROC curve (Az)

Results: Reasonable correspondence between theoretical calculations and human observer performance was achieved for all imaging tasks over the broad range of experimental conditions and acquisition schemes. The PW and PWEi observer models tended to overestimate detectability, while the various NPW models predicted observer performance fairly well, with NPWEi giving the best overall agreement. Detectability was shown to increase with θtot due to the reduction of out-of-plane clutter, reaching a plateau after a particular θtot that depended on the imaging task. Depending on the acquisition scheme, however (i.e., constant-Nproj or Δθ), detectability was seen in some cases to decline at higher θtot due to tradeoffs among quantum noise, background clutter, and view sampling.

Conclusions: Generalized detectability index derived from a 3D cascaded systems model shows reasonable correspondence with human observer performance over a fairly broad range of imaging tasks and conditions, although discrepancies were observed in cases relating to orbits intermediate to 180° and 360°. The basic correspondence of theoretical and measured performance supports the application of such a theoretical framework for system design and optimization of tomosynthesis and CBCT.

/pdf/analysis-of-fourier-domain-task-based-detectability-index-in-50t127buj6.pdf

Analysis of Fourier-domain task-based detectability index in tomosynthesis and cone-beam CT in relation to human observer performance

Computed tomography (CT) is an essential tool in diagnostic imaging for evaluating many clinical conditions. In recent years, there have been several notable advances in CT technology that already have had or are expected to have a significant clinical impact, including extreme multidetector CT, iterative reconstruction algorithms, dual-energy CT, cone-beam CT, portable CT, and phase-contrast CT. These techniques and their clinical applications are reviewed and illustrated in this article. In addition, emerging technologies that address deficiencies in these modalities are discussed.

https://www.annualreviews.org/doi/pdf/10.1146/annurev-bioeng-121813-113601

Advances in computed tomography imaging technology.

X-ray mammography of the compressed breast is well recognized as the "gold standard" for early detection of breast cancer, but its performance is not ideal. One limitation of screening mammography is tissue superposition, particularly for dense breasts. Since 2001, several research groups in the USA and in the European Union have developed computed tomography (CT) systems with digital detector technology dedicated to x-ray imaging of the uncompressed breast (breast CT or BCT) for breast cancer screening and diagnosis. This CT technology--tracing back to initial studies in the 1970s--allows some of the limitations of mammography to be overcome, keeping the levels of radiation dose to the radiosensitive breast glandular tissue similar to that of two-view mammography for the same breast size and composition. This paper presents an evaluation of the research efforts carried out in the invention, development, and improvement of BCT with dedicated scanners with state-of-the-art technology, including initial steps toward commercialization, after more than a decade of R&D in the laboratory and/or in the clinic. The intended focus here is on the technological/engineering aspects of BCT and on outlining advantages and limitations as reported in the related literature. Prospects for future research in this field are discussed.

Dedicated breast computed tomography: Basic aspects.

OBJECTIVE. The primary objectives of this pilot study were to evaluate the radiation dose, breast coverage, and image quality of cone-beam breast CT compared with a conventional mammographic examination. Image quality analysis was focused on the concordance of cone-beam breast CT with conventional mammography in terms of mammographic findings.SUBJECTS AND METHODS. This prospective study was performed from July 2006 through August 2008. Twenty-three women were enrolled who met the inclusion criteria, which were age 40 years or older with final BI-RADS assessment category 1 or 2 lesions on conventional mammograms within the previous 6 months. The breasts were imaged with a flat-panel detector-based cone-beam CT system, and the images were reviewed with a 3D visualization system. Cone-beam breast CT image data sets and the corresponding mammograms were reviewed by three qualified mammographers. The parameters assessed and compared in this pilot study were radiation dose, breast tissue coverage, and image qua...

https://www.ajronline.org/doi/pdf/10.2214/AJR.08.1017

Lawrence Sahler

Papers

Cone-Beam CT for Breast Imaging: Radiation Dose, Breast Coverage, and Image Quality