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3D Symmetry Measure Invariant to Subject Pose During Image Acquisition.

Kawale M, Lee J, Leung SY, Fingeret MC, Reece GP, Crosby MA, Beahm EK, Markey MK, Merchant FA - Breast Cancer (Auckl) (2011)

Bottom Line: In order to quantify the effect of pose, we introduce a new measure; the 3D pBRA (Percentage Breast Retraction Assessment) index, and validate its use against the 2D pBRA index.The quantitative assessment of 3D asymmetry was found to be invariant of subject pose.Problems with pose that are inherent in 2D photographs are avoided and fiducial point identification is made easier by being able to panoramically rotate the 3D surface enabling views from any desired angle.

View Article: PubMed Central - PubMed

Affiliation: Department of Computer Science, University of Houston, Houston, Texas, USA.

ABSTRACT
In this study we evaluate the influence of subject pose during image acquisition on quantitative analysis of breast morphology. Three (3D) and two-dimensional (2D) images of the torso of 12 female subjects in two different poses; (1) hands-on-hip (HH) and (2) hands-down (HD) were obtained. In order to quantify the effect of pose, we introduce a new measure; the 3D pBRA (Percentage Breast Retraction Assessment) index, and validate its use against the 2D pBRA index. Our data suggests that the 3D pBRA index is linearly correlated with the 2D counterpart for both of the poses, and is independent of the localization of fiducial points within a tolerance limit of 7 mm. The quantitative assessment of 3D asymmetry was found to be invariant of subject pose. This study further corroborates the advantages of 3D stereophotogrammetry over 2D photography. Problems with pose that are inherent in 2D photographs are avoided and fiducial point identification is made easier by being able to panoramically rotate the 3D surface enabling views from any desired angle.

No MeSH data available.


Related in: MedlinePlus

Inter- and intra-observer variability in localization of fiducial points. A) The black and blue points are marked by the same user in two different trials. Although 1 cm apart from each other, they represent the same fiducial point i.e., Nipple. B) Similarly, the black and blue points are the points marked by two different observers. These points are greater than 1 cm apart but when observed on the image, they represent the SN. This indicates despite the variability (∼10 mm) in localizations of fiducial points, the calculation of 3D pBRA is reliable as long as these points represent the same fiducial point.
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f3-bcbcr-5-2011-131: Inter- and intra-observer variability in localization of fiducial points. A) The black and blue points are marked by the same user in two different trials. Although 1 cm apart from each other, they represent the same fiducial point i.e., Nipple. B) Similarly, the black and blue points are the points marked by two different observers. These points are greater than 1 cm apart but when observed on the image, they represent the SN. This indicates despite the variability (∼10 mm) in localizations of fiducial points, the calculation of 3D pBRA is reliable as long as these points represent the same fiducial point.

Mentions: Low variability (Davg = 4.2 ± 1.08 mm for HD and Davg = 4.1 ± 0.69 mm for HH) was observed in the identification of nipples, whereas localization of the sternal notch showed slightly higher variability (Davg = 6.05 ± 1.6 mm for HD and Davg = 5.5 ± 0.57 mm for HH). Overall, the observers were found to be more consistent over time in marking all of the fiducial points for both poses as indicated by lower intra-observer variability when compared to the inter-observer variability. It should be noted that although we have quantitatively defined Davg > 7 mm as an indication of high variability in the annotation of fiducial points, a qualitative visualization of fiducial points identified at distances greater than 1 cm (10 mm) apart appears to be in close proximity and within the local area of the landmark. For example, as seen in Figure 3A and 3B, fiducial points at a distance of 1 cm are found to be located within the local neighborhood of the landmark and, thus, can be qualitatively visualized to be the appropriate representations of the same fiducial point.


3D Symmetry Measure Invariant to Subject Pose During Image Acquisition.

Kawale M, Lee J, Leung SY, Fingeret MC, Reece GP, Crosby MA, Beahm EK, Markey MK, Merchant FA - Breast Cancer (Auckl) (2011)

Inter- and intra-observer variability in localization of fiducial points. A) The black and blue points are marked by the same user in two different trials. Although 1 cm apart from each other, they represent the same fiducial point i.e., Nipple. B) Similarly, the black and blue points are the points marked by two different observers. These points are greater than 1 cm apart but when observed on the image, they represent the SN. This indicates despite the variability (∼10 mm) in localizations of fiducial points, the calculation of 3D pBRA is reliable as long as these points represent the same fiducial point.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3140267&req=5

f3-bcbcr-5-2011-131: Inter- and intra-observer variability in localization of fiducial points. A) The black and blue points are marked by the same user in two different trials. Although 1 cm apart from each other, they represent the same fiducial point i.e., Nipple. B) Similarly, the black and blue points are the points marked by two different observers. These points are greater than 1 cm apart but when observed on the image, they represent the SN. This indicates despite the variability (∼10 mm) in localizations of fiducial points, the calculation of 3D pBRA is reliable as long as these points represent the same fiducial point.
Mentions: Low variability (Davg = 4.2 ± 1.08 mm for HD and Davg = 4.1 ± 0.69 mm for HH) was observed in the identification of nipples, whereas localization of the sternal notch showed slightly higher variability (Davg = 6.05 ± 1.6 mm for HD and Davg = 5.5 ± 0.57 mm for HH). Overall, the observers were found to be more consistent over time in marking all of the fiducial points for both poses as indicated by lower intra-observer variability when compared to the inter-observer variability. It should be noted that although we have quantitatively defined Davg > 7 mm as an indication of high variability in the annotation of fiducial points, a qualitative visualization of fiducial points identified at distances greater than 1 cm (10 mm) apart appears to be in close proximity and within the local area of the landmark. For example, as seen in Figure 3A and 3B, fiducial points at a distance of 1 cm are found to be located within the local neighborhood of the landmark and, thus, can be qualitatively visualized to be the appropriate representations of the same fiducial point.

Bottom Line: In order to quantify the effect of pose, we introduce a new measure; the 3D pBRA (Percentage Breast Retraction Assessment) index, and validate its use against the 2D pBRA index.The quantitative assessment of 3D asymmetry was found to be invariant of subject pose.Problems with pose that are inherent in 2D photographs are avoided and fiducial point identification is made easier by being able to panoramically rotate the 3D surface enabling views from any desired angle.

View Article: PubMed Central - PubMed

Affiliation: Department of Computer Science, University of Houston, Houston, Texas, USA.

ABSTRACT
In this study we evaluate the influence of subject pose during image acquisition on quantitative analysis of breast morphology. Three (3D) and two-dimensional (2D) images of the torso of 12 female subjects in two different poses; (1) hands-on-hip (HH) and (2) hands-down (HD) were obtained. In order to quantify the effect of pose, we introduce a new measure; the 3D pBRA (Percentage Breast Retraction Assessment) index, and validate its use against the 2D pBRA index. Our data suggests that the 3D pBRA index is linearly correlated with the 2D counterpart for both of the poses, and is independent of the localization of fiducial points within a tolerance limit of 7 mm. The quantitative assessment of 3D asymmetry was found to be invariant of subject pose. This study further corroborates the advantages of 3D stereophotogrammetry over 2D photography. Problems with pose that are inherent in 2D photographs are avoided and fiducial point identification is made easier by being able to panoramically rotate the 3D surface enabling views from any desired angle.

No MeSH data available.


Related in: MedlinePlus