The potential role of three-dimensional surface imaging as a tool to evaluate aesthetic outcome after Breast Conserving Therapy (BCT).

Purpose To establish whether objective measurements of symmetry of volume and shape using three-dimensional surface imaging (3D-SI) can be used as surrogate markers of aesthetic outcome in patients who have undergone breast conserving therapy (BCT).Methods Women who had undergone unilateral BCT in the preceding 1-6 years were invited to participate. Participants completed a satisfaction questionnaire (BREAST-Q) and underwent 3D-SI. Volume and surface symmetry were measured on the images. Assessment of aesthetic outcome was undertaken by a panel of clinicians. The Kruskal-Wallis test was used to assess the relationship between volume and shape symmetry measurements with the panel score. Spearman's rho correlations were used to assess the relationship between the measurements and patient satisfaction.Results 200 women participated. Median volume symmetry was 87% (IQR 78-93) and shape symmetry was 5.9 mm (IQR 4.2-8.0). The participants were grouped according to panel assessment of aesthetic outcome (poor, fair, good, excellent) and the median volume and shape symmetry was calculated for each group. Volume symmetry significantly differed between the groups. Post hoc pairwise comparisons demonstrated that these differences existed between panel scores of fair versus good and good versus excellent. Median shape symmetry also differed according to patient panel groups with four significant pairwise comparisons between poor versus good, poor versus excellent, fair versus good and fair versus excellent. There was a significant but weak correlation of both volume symmetry and surface asymmetry with BREAST-Q scores (correlation coefficients 0.187 and -0.229, respectively).Conclusion Breast volume and shape symmetry are both associated with panel assessment scores and patient satisfaction. The objective volume and shape symmetry measures were strongly associated with panel assessment scores, such that a 3D-SI tool could replace panel assessment as a faster and more objective method of evaluating aesthetic outcomes

Analysis of motion during the breast clamping phase of mammography

Objectives: To measure paddle motion during the clamping phase of a breast phantom for a range of machine/paddle combinations. Methods: A deformable breast phantom was used to simulate a female breast. Twelve mammography machines from three manufacturers with twenty two flexible and twenty fixed paddles were evaluated. Vertical motion at the paddle was measured using two calibrated linear potentiometers. For each paddle, the motion in millimeters was recorded every 0.5 seconds for 40 seconds while the phantom was compressed with 80 N. Independent t-tests were used to determine differences in paddle motion between flexible and fixed, small and large, GE Senographe Essential and Hologic Selenia Dimensions paddles. Paddle tilt in the medial-lateral plane for each machine/paddle combination was calculated. Results: All machine/paddle combinations demonstrate highest levels of motion during the first 10s of the clamping phase. Least motion is 0.17±0.05 mm/10s (n=20) and the most is 0.51±0.15 mm/10s (n=80). There is a statistical difference in paddle motion between fixed and flexible (p<0.001), GE Senographe Essential and Hologic Selenia Dimensions paddles (p<0.001). Paddle tilt in the medial-lateral plane is independent of time and varied from 0.04° to 0.69°. Conclusions: All machine/paddle combinations exhibited motion and tilting and the extent varied with machine and paddle sizes and types. Advances in knowledge: This research suggests that image blurring will likely be clinically insignificant 4 seconds or more after the clamping phase commences

Nonrigid reconstruction of 3D breast surfaces with a low-cost RGBD camera for surgical planning and aesthetic evaluation

Accounting for 26% of all new cancer cases worldwide, breast cancer remains the most common form of cancer in women. Although early breast cancer has a favourable long-term prognosis, roughly a third of patients suffer from a suboptimal aesthetic outcome despite breast conserving cancer treatment. Clinical-quality 3D modelling of the breast surface therefore assumes an increasingly important role in advancing treatment planning, prediction and evaluation of breast cosmesis. Yet, existing 3D torso scanners are expensive and either infrastructure-heavy or subject to motion artefacts. In this paper we employ a single consumer-grade RGBD camera with an ICP-based registration approach to jointly align all points from a sequence of depth images non-rigidly. Subtle body deformation due to postural sway and respiration is successfully mitigated leading to a higher geometric accuracy through regularised locally affine transformations. We present results from 6 clinical cases where our method compares well with the gold standard and outperforms a previous approach. We show that our method produces better reconstructions qualitatively by visual assessment and quantitatively by consistently obtaining lower landmark error scores and yielding more accurate breast volume estimates

The potential role of three-dimensional surface imaging as a tool to evaluate aesthetic outcome after Breast Conserving Therapy (BCT)

To establish whether objective measurements of symmetry of volume and shape using three-dimensional surface imaging (3D-SI) can be used as surrogate markers of aesthetic outcome in patients who have undergone breast conserving therapy (BCT). Women who had undergone unilateral BCT in the preceding 1-6 years were invited to participate. Participants completed a satisfaction questionnaire (BREAST-Q) and underwent 3D-SI. Volume and surface symmetry were measured on the images. Assessment of aesthetic outcome was undertaken by a panel of clinicians. The Kruskal-Wallis test was used to assess the relationship between volume and shape symmetry measurements with the panel score. Spearman's rho correlations were used to assess the relationship between the measurements and patient satisfaction. 200 women participated. Median volume symmetry was 87% (IQR 78-93) and shape symmetry was 5.9 mm (IQR 4.2-8.0). The participants were grouped according to panel assessment of aesthetic outcome (poor, fair, good, excellent) and the median volume and shape symmetry was calculated for each group. Volume symmetry significantly differed between the groups. Post hoc pairwise comparisons demonstrated that these differences existed between panel scores of fair versus good and good versus excellent. Median shape symmetry also differed according to patient panel groups with four significant pairwise comparisons between poor versus good, poor versus excellent, fair versus good and fair versus excellent. There was a significant but weak correlation of both volume symmetry and surface asymmetry with BREAST-Q scores (correlation coefficients 0.187 and -0.229, respectively). Breast volume and shape symmetry are both associated with panel assessment scores and patient satisfaction. The objective volume and shape symmetry measures were strongly associated with panel assessment scores, such that a 3D-SI tool could replace panel assessment as a faster and more objective method of evaluating aesthetic outcomes

Nonrigid reconstruction of 3D breast surfaces with a low-cost RGBD camera for surgical planning and aesthetic evaluation

Accounting for 26% of all new cancer cases worldwide, breast cancer remains the most common form of cancer in women. Although early breast cancer has a favourable long-term prognosis, roughly a third of patients suffer from a suboptimal aesthetic outcome despite breast conserving cancer treatment. Clinical-quality 3D modelling of the breast surface therefore assumes an increasingly important role in advancing treatment planning, prediction and evaluation of breast cosmesis. Yet, existing 3D torso scanners are expensive and either infrastructure-heavy or subject to motion artefacts. In this paper we employ a single consumer-grade RGBD camera with an ICP-based registration approach to jointly align all points from a sequence of depth images non-rigidly. Subtle body deformation due to postural sway and respiration is successfully mitigated leading to a higher geometric accuracy through regularised locally affine transformations. We present results from 6 clinical cases where our method compares well with the gold standard and outperforms a previous approach. We show that our method produces better reconstructions qualitatively by visual assessment and quantitatively by consistently obtaining lower landmark error scores and yielding more accurate breast volume estimates

Mammography machine compression paddle movement andobserver performance analysis

Full field digital mammography (FFDM) was introduced into the United Kingdom (UK) as a replacement for screen-film mammography (SFM) in 2005. Since then, individual breast screening centres have begun to report blurred images through local audits. Blurring was probably present in SFM as well, however the improvement in contrast resolution in FFDM may have made it more apparent. The sources of blurring include improper imaging techniques, patient movement caused by breathing and heart motion,the viscoelastic motion of the breast, and paddle motion. This thesis aims to test the hypothesis that paddle motion might cause image blur. It investigates whether blurring can be detected visually on technical review monitors and reporting grade monitors.The thesis presents a method to minimise paddle motion during X-ray exposure. Six papers have been published. Two of these (papers 1 and 2) investigated paddle displacement using linear potentiometers. Three investigated the influence of paddle motion on image quality. Paper 3 investigated whether paddle motion can cause image blur; paper 4 determined the minimum amount of simulated motion required for the visual detection of blurring; and paper 5 evaluated the practitioner’s ability to identify blurring on monitors with different resolutions (2.3 MP and 5 MP). The final research paper (paper 6) investigated a way to reduce paddle displacement settling time; this involved the use of a closed-loop control system.Results: In papers 1 and 2 paddle displacement followed a bi-exponential function with a settling time of approximately 40 s. The use of average paddle displacement to estimate the amount of paddle motion would underestimate the worst case of the threedifferent runs of the experiment. The estimated paddle motion would be greatly reduced if the time of exposure is delayed from 5 to 10 s. In paper 3 all metal ball bearings shown increased in diameters and the range of magnification varied from 1.04 to 1.21. T-test results shown that there was a significant difference (p < 0.05) in the ball bearing diameters between the intensity thresholding and the edge detection methods for all paddle/ compression force combinations. The ball bearing diameters calculated by the intensity thresholding method had higher variability than the edge detection method.In paper 4 the soft-edged mask method best represented the physical process that caused the blurring effect and was chosen as the standard simulation approach for motion blurring. The ratio between the vertical paddle motion and the horizontal breast motion estimated by the mathematical model is approximately 1:0.3.In paper 5 the angular size calculation shown that for a viewing distance of 75 cm the screen resolution for 5 MP and 12 MP monitors was better than the observer eyes' resolution. For a viewing distance of 30 cm the observer eyes' resolution was betterthan the screen resolution for 2.3 MP, 5 MP and 12 MP monitors. Among all three monitors, image displayed on the 12 MP monitor has the lowest loss in image quality after interpolation. In paper 6 the simulation results shown that force overshoot is possible for position control system. Force overshoot occurred almost instantaneously for step input and its magnitude is about 10 times larger than the ramp input. Force overshoot and steadystateerror can be eliminated by the use of force control system.Conclusion: The magnitude of calculated paddle motion is much lower than the minimum amount of simulated motion required for the visual detection of blurring. Mathematical models have shown that vertical paddle motion caused a smaller horizontal breast displacement when compressed. Therefore, there is no sufficientevidence to support the hypothesis that paddle motion is a cause of image blurring in FFDM