Scatter correction in digital mammography based on image deconvolution

Ducote, Justin L.; Molloi, Sabee

doi:10.1088/0031-9155/55/5/003

Cited by 48 publications

(57 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Scatter can be estimated by Monte Carlo (MC) simulations, but this is extremely time-consuming, and it is therefore attractive to use a faster convolution-based method of scatter estimation [1][2][3] , with an appropriate scatter kernel. We have tested this approach by comparing direct MC calculations of the scatter-to-primary ratio (SPR) obtained when using a realistic anthropomorphic phantom to simulate the breast and convolution-based calculations with scatter kernels determined for breast phantoms of uniform thickness and composition.…”

Section: Introductionmentioning

confidence: 99%

A fast scatter field estimator for digital breast tomosynthesis

et al. 2012

View full text Add to dashboard Cite

Digital breast tomosynthesis (DBT) is a promising alternative approach to overcome the limitations of tissue superposition found in full-field 2D digital mammography. However, due to the absence of anti-scatter grids in DBT, accurate scatter estimation for each projection is necessary for modelling the image reconstruction stage. In this work we identify the limitations associated with scatter estimation using spatial invariant scatter kernels, in particular at the edge region where such methods result in scatter overestimation. Such approaches show an overestimation of scatter-to-primary ratio of over 50% at the edges when compared with results from direct Monte Carlo simulation. This problem was found to increase with projection angle. Simulation work presented here shows that this overestimation in scatter is largely due to air gap between the lower curved breast edge and the detector. We propose a new fast, accurate scatter field estimator for use in DBT which not only considers the breast thickness and primary incidence angle, but also accounts for scatter exiting the breast edge region and traversing an air gap prior to absorption in the detector. The new proposed scatter estimator represents an alternative approach to this problem which reduces discrepancies at the edge of a breast phantom. Moreover, the time required for generating scatter has dropped from approximately 12 hours using Monte Carlo simulations for 10 10 photons to just a few minutes per projection. The insertion of scatter from the compression paddle to aforementioned methodologies is also discussed.

show abstract

Section: Introductionmentioning

confidence: 99%

A fast scatter field estimator for digital breast tomosynthesis

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Images were acquired at 30 frames/s. All images were corrected for X-ray scatter before logarithmic transformation (7). A publicly available software (Image J, NIH, Bethesda, MD) was used for image analysis.…”

Section: Methodsmentioning

confidence: 99%

Assessment of coronary microcirculation in a swine animal model

Zhang

Takarada

Molloi

2011

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

Coronary microvascular dysfunction has important prognostic implications. Several hemodynamic indexes, such as coronary flow reserve (CFR), microvascular resistance, and zero-flow pressure (Pzf), were used to establish the most reliable index to assess coronary microcirculation. Fifteen swine were instrumented with a flow probe, and a pressure wire was advanced into the distal left anterior descending artery. Adenosine was used to produce maximum hyperemia. Microspheres were used to create microvascular dysfunction. An occluder was used to produce stenosis. Blood flow from the probe (Q p), aortic pressure, distal coronary pressure, and right atrium pressure were recorded. Angiographic flow (Q a) was calculated using a time-density curve. Flow probe-based CFR and angiographic CFR were calculated using Q p and Q a, respectively. Flow probe-based (NMRqh) and angiographic normalized microvascular resistance (NMRah) were determined using Q p and Q a, respectively, during hyperemia. Pzf was calculated using Q p and distal coronary pressure. Two series of receiver operating characteristic curves were generated: normal epicardial artery model (N model) and stenosis model (S model). The areas under the receiver operating characteristic curves for flow probe-based CFR, angiographic CFR, NMRqh, NMRah, and Pzf were 0. 855, 0.836, 0.976, 0.956, and 0.855 in N model and 0.737, 0.700, 0.935, 0.889, and 0.698 in S model. Both NMRqh and NMRah were significantly more reliable than CFR and Pzf in detecting the microvascular deterioration. Compared with CFR and Pzf, NMR provided a more accurate assessment of microcirculation. This improved accuracy was more prevalent when stenosis existed. Moreover, NMRah is potentially a less invasive method for assessing coronary microcirculation.angiography; blood flow; cardiovascular imaging; coronary microvascular function CORONARY ANGIOGRAPHY, a routine examination for patients with heart disease, provides an assessment of stenosis severity by visualizing the opacified arterial lumen. However, in many cases (12,40), the severity of myocardium ischemia correlates poorly with epicardial stenosis. Therefore, intracoronary physiological techniques have been developed to provide physiological evaluations for patients who undergo coronary angiography (8,34). Recently, the medical community's interest in coronary microcirculation has grown with the increasing awareness that microvascular dysfunction occurs in a number of myocardial disease states and has important prognostic implications (19,20). With this recognition comes the need for a method to accurately assess the functional capacity of coronary microcirculation for diagnostic purposes and to monitor the effects of therapeutic interventions targeted at reversing the extent of coronary microvascular dysfunction. To assess changes in the microcirculatory bed, several indexes have been proposed, such as coronary flow reserve (CFR), microvascular resistance (MR), and zero-flow pressure (P zf ). In the early 1990s, Gould et al. (14) introduced CFR...

show abstract

“…The detector signal in each pixel was digitized with 14-bit precision. All images were corrected for X-ray scatter before logarithmic transformation (10). A publicly available software (ImageJ, National Institutes of Health, Bethesda, MD) was used for image analysis.…”

Section: Protocolmentioning

confidence: 99%

Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation

Zhang

Takarada

Molloi

2011

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

Zhang Z, Takarada S, Molloi S. Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation. Am J Physiol Heart Circ Physiol 300: H2096 -H2104, 2011. First published March 11, 2011 doi:10.1152/ajpheart.01123.2010.-Structural coronary microcirculation abnormalities are important prognostic determinants in clinical settings. However, an assessment of microvascular resistance (MR) requires a velocity wire. A first-pass distribution analysis technique to measure volumetric blood flow has been previously validated. The aim of this study was the in vivo validation of the MR measurement technique using first-pass distribution analysis. Twelve anesthetized swine were instrumented with a transit-time ultrasound flow probe on the proximal segment of the left anterior descending coronary artery (LAD). Microspheres were injected into the LAD to create a model of microvascular dysfunction. Adenosine (400 g·kg Ϫ1 ·min Ϫ1 ) was used to produce maximum hyperemia. A region of interest in the LAD arterial bed was drawn to generate time-density curves using angiographic images. Volumetric blood flow measurements (Q a) were made using a time-density curve and the assumption that blood was momentarily replaced with contrast agent during the injection. Blood flow from the flow probe (Qp), coronary pressure (Pa), and right atrium pressure (Pv) were continuously recorded. Flow probe-based normalized MR (NMRp) and angiography-based normalized MR (NMRa) were calculated using Qp and Qa, respectively. In 258 measurements, Qa showed a strong correlation with the gold standard Qp (Qa ϭ 0.90 Qp ϩ 6.6 ml/min, r 2 ϭ 0.91, P Ͻ 0.0001). NMRa correlated linearly with NMRp (NMRa ϭ 0.90 NMRp ϩ 0.02 mmHg·ml Ϫ1 ·min Ϫ1 , r 2 ϭ 0.91, P Ͻ 0.0001). Additionally, the BlandAltman analysis showed a close agreement between NMRa and NMRp. In conclusion, a technique based on angiographic image data for quantifying NMR was validated using a swine model. This study provides a method to measure NMR without using a velocity wire, which can potentially be used to evaluate microvascular conditions during coronary arteriography. coronary microvasculation CORONARY MICROVASCULAR DYSFUNCTION occurs in a number of myocardial disease states and has important prognostic implications in different clinical settings, including acute coronary syndromes, diabetic coronary disease, hypertrophic cardiomyopathy, and transplant cardiac allograft vasculopathy (25,26,39). Intracoronary physiological techniques have been advocated and several indexes for the assessment of changes in the microcirculatory bed have been proposed (2, 11, 51), such as coronary flow reserve (CFR) (9, 13, 34) and microvascular resistance (MR) (12,39,49). Many previous study findings suggest that MR is a useful variable for directly assessing microcirculatory function. In 1974, Gould et al. (19, 20, 21) postulated a hypothesis that minimum MR is independent of epicardial stenosis severity. Recently, Fearon and colleagues (1,7,12,14...

show abstract

Scatter correction in digital mammography based on image deconvolution

Cited by 48 publications

References 24 publications

A fast scatter field estimator for digital breast tomosynthesis

A fast scatter field estimator for digital breast tomosynthesis

Assessment of coronary microcirculation in a swine animal model

Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation

Contact Info

Product

Resources

About