PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (32)
 

Clipboard (0)
None

Select a Filter Below

Year of Publication
1.  Plastic Surgeon Expertise in Predicting Breast Reconstruction Outcomes for Patient Decision Analysis 
Background
Decision analysis offers a framework that may help breast cancer patients make good breast reconstruction decisions. A requirement for this type of analysis is information about the possibility of outcomes occurring in the form of probabilities. The purpose of this study was to determine if plastic surgeons are good sources of probability information, both individually and as a group, when data are limited.
Methods
Seven plastic surgeons were provided with pertinent medical information and preoperative photographs of patients, and were asked to assign probabilities to predict number of revisions, complications, and final aesthetic outcome using a questionnaire designed for the study. Logarithmic strictly proper scoring was used to evaluate the surgeons’ abilities to predict breast reconstruction outcomes. Surgeons’ responses were analyzed for calibration and confidence in their answers.
Results
As individuals, there was variation in surgeons’ ability to predict outcomes. For each prediction category, a different surgeon was more accurate. As a group, surgeons possessed knowledge of future events despite not being well calibrated in their probability assessments. Prediction accuracy for the group was up to six-fold greater than that of the best individual.
Conclusions
The use of individual plastic surgeon-elicited probability information is not encouraged unless the individual’s prediction skill has been evaluated. In the absence of this information, a group consensus on the probability of outcomes is preferred. Without a large evidence base for calculating probabilities, estimates assessed from a group of plastic surgeons may be acceptable for purposes of breast reconstruction decision analysis.
doi:10.1097/GOX.0000000000000010
PMCID: PMC4044723  PMID: 24910814
2.  Differentiating tumor recurrence from treatment necrosis: a review of neuro-oncologic imaging strategies 
Neuro-Oncology  2013;15(5):515-534.
Differentiating treatment-induced necrosis from tumor recurrence is a central challenge in neuro-oncology. These 2 very different outcomes after brain tumor treatment often appear similarly on routine follow-up imaging studies. They may even manifest with similar clinical symptoms, further confounding an already difficult process for physicians attempting to characterize a new contrast-enhancing lesion appearing on a patient's follow-up imaging. Distinguishing treatment necrosis from tumor recurrence is crucial for diagnosis and treatment planning, and therefore, much effort has been put forth to develop noninvasive methods to differentiate between these disparate outcomes. In this article, we review the latest developments and key findings from research studies exploring the efficacy of structural and functional imaging modalities for differentiating treatment necrosis from tumor recurrence. We discuss the possibility of computational approaches to investigate the usefulness of fine-grained imaging characteristics that are difficult to observe through visual inspection of images. We also propose a flexible treatment-planning algorithm that incorporates advanced functional imaging techniques when indicated by the patient's routine follow-up images and clinical condition.
doi:10.1093/neuonc/nos307
PMCID: PMC3635510  PMID: 23325863
functional imaging, neuro-oncology; pseudoprogression; tumor recurrence; treatment necrosis
3.  Assessing Women’s Preferences and Preference Modeling for Breast Reconstruction Decision Making 
Background:
Women considering breast reconstruction must make challenging trade-offs among issues that often conflict. It may be useful to quantify possible outcomes using a single summary measure to aid a breast cancer patient in choosing a form of breast reconstruction.
Methods:
In this study, we used multiattribute utility theory to combine multiple objectives to yield a summary value using 9 different preference models. We elicited the preferences of 36 women, aged 32 or older with no history of breast cancer, for the patient-reported outcome measures of breast satisfaction, psychosocial well-being, chest well-being, abdominal well-being, and sexual well-being as measured by the BREAST-Q in addition to time lost to reconstruction and out-of-pocket cost. Participants ranked hypothetical breast reconstruction outcomes. We examined each multiattribute utility preference model and assessed how often each model agreed with participants’ rankings.
Results:
The median amount of time required to assess preferences was 34 minutes. Agreement among the 9 preference models with the participants ranged from 75.9% to 78.9%. None of the preference models performed significantly worse than the best-performing risk-averse multiplicative model. We hypothesize an average theoretical agreement of 94.6% for this model if participant error is included. There was a statistically significant positive correlation with more unequal distribution of weight given to the 7 attributes.
Conclusions:
We recommend the risk-averse multiplicative model for modeling the preferences of patients considering different forms of breast reconstruction because it agreed most often with the participants in this study.
doi:10.1097/GOX.0000000000000062
PMCID: PMC4120963  PMID: 25105083
4.  Plastic Surgeon Expertise in Predicting Breast Reconstruction Outcomes for Patient Decision Analysis 
Background:
Decision analysis offers a framework that may help breast cancer patients make good breast reconstruction decisions. A requirement for this type of analysis is information about the possibility of outcomes occurring in the form of probabilities. The purpose of this study was to determine if plastic surgeons are good sources of probability information, both individually and as a group, when data are limited.
Methods:
Seven plastic surgeons were provided with pertinent medical information and preoperative photographs of patients and were asked to assign probabilities to predict number of revisions, complications, and final aesthetic outcome using a questionnaire designed for the study. Logarithmic strictly proper scoring was used to evaluate the surgeons’ abilities to predict breast reconstruction outcomes. Surgeons’ responses were analyzed for calibration and confidence in their answers.
Results:
As individuals, there was variation in surgeons’ ability to predict outcomes. For each prediction category, a different surgeon was more accurate. As a group, surgeons possessed knowledge of future events despite not being well calibrated in their probability assessments. Prediction accuracy for the group was up to 6-fold greater than that of the best individual.
Conclusions:
The use of individual plastic surgeon–elicited probability information is not encouraged unless the individual’s prediction skill has been evaluated. In the absence of this information, a group consensus on the probability of outcomes is preferred. Without a large evidence base for calculating probabilities, estimates assessed from a group of plastic surgeons may be acceptable for purposes of breast reconstruction decision analysis.
doi:10.1097/GOX.0000000000000010
PMCID: PMC4044723  PMID: 24910814
5.  Retinal nerve fiber layer reflectance for early glaucoma diagnosis 
Journal of glaucoma  2014;23(1):10.1097/IJG.0b013e31829ea2a7.
Purpose
Compare performance of normalized reflectance index (NRI) and retinal nerve fiber layer thickness (RNFLT) parameters determined from OCT images for glaucoma and glaucoma suspect diagnosis.
Methods
Seventy-five eyes from seventy-one human subjects were studied: 33 controls, 24 glaucomatous, and 18 glaucoma-suspects. RNFLT and NRI maps were measured using two custom-built OCT systems and the commercial instrument RTVue. Using area under the receiver operating characteristic (ROC) curve, RNFLT and NRI measured in seven RNFL locations were analyzed to distinguish between control, glaucomatous, and glaucoma-suspect eyes.
Results
The mean NRI of the control group was significantly larger than the means of glaucomatous and glaucoma-suspect groups in most RNFL locations for all three OCT systems (p<0.05 for all comparisons). NRI performs significantly better than RNFLT at distinguishing between glaucoma-suspect and control eyes using RTVue OCT (p=0.008). The performances of NRI and RNFLT for classifying glaucoma-suspect vs. control eyes were statistically indistinguishable for PS-OCT-EIA (p=0.101) and PS-OCT-DEC (p=0.227). The performances of NRI and RNFLT for classifying glaucomatous vs. control eyes were statistically indistinguishable (PS-OCT-EIA: p=0.379; PS-OCT-DEC: p=0.338; RTVue OCT: p=0.877).
Conclusions
NRI is a promising measure for distinguishing between glaucoma-suspect and control eyes and may indicate disease in the pre-perimetric stage. Results of this pilot clinical study warrant a larger study to confirm the diagnostic power of NRI for diagnosing pre-perimetric glaucoma.
doi:10.1097/IJG.0b013e31829ea2a7
PMCID: PMC3844555  PMID: 23835671
glaucoma; optical coherence tomography; retinal nerve fiber layer
6.  Automated calculation of symmetry measure on clinical photographs 
1 ABSTRACT
Breast cancer is one of the most prevalent forms of cancer in the world. More than 250,000 American women are diagnosed with breast cancer annually. Fortunately, the survival rate is relatively high and continually increasing due to improved detection techniques and treatment methods. The quality of life of breast cancer survivors is ameliorated by minimizing adverse effects on their physical appearance. Breast reconstruction is important for restoring the survivor’s appearance. In breast reconstructive surgery, there is a need to develop technologies for quantifying surgical outcomes and understanding women’s perceptions of changes in their appearance. Methods for objectively measuring breast anatomy are needed in order to help breast cancer survivors, radiation oncologists, and surgeons quantify changes in appearance that occur with different breast reconstructive surgical options. In this study, we present an automated method for computing a variant of the normalized Breast Retraction Assessment (pBRA), a common measure of symmetry, from routine clinical photographs taken to document breast cancer treatment procedures.
doi:10.1111/j.1365-2753.2010.01477.x
PMCID: PMC2958233  PMID: 20630015
BRA; pBRA; Automated Detection; Digital Photographs; Umbilicus; Nipple Complex; Breast Cancer
7.  Quantifying the Aesthetic Outcomes of Breast Cancer Treatment: Assessment of Surgical Scars from Clinical Photographs 
Accurate assessment of the degree of scaring that results from surgical intervention for breast cancer would enable more effective pre-operative counseling. The resultant scar that accompanies an open surgical intervention may be characterized by variance in thickness, color, and contour. These factors significantly impact the overall appearance of the breast. A number of studies have addressed the mechanical and pathologic aspects of scarring. The majority of these investigations have focused on the physiologic process of scar formation and means to improve the qualities of a scar. Few studies have focused on quantifying the visual impact of scars. This manuscript critically reviews current methods used to assess scars in terms of overall satisfaction after surgery. We introduce objective, quantitative measures for assessing linear breast surgical scars using digital photography. These new measurements of breast surgical scars are based on calculations of contrast and area. We demonstrate, using the intra-class correlation coefficient (ICC), that the new measures are robust to observer variability in annotating the scar region on clinical photographs. As an example of the utility of the new measures, we use them to quantify the aesthetic differences of reconstruction following skin-sparing mastectomy vs. conventional mastectomy.
doi:10.1111/j.1365-2753.2010.01476.x
PMCID: PMC2958242  PMID: 20630016
Aesthetics; Breast Neoplasm; Esthetics; Mastectomy; Outcomes; Prostheses and Implants; Reconstructive Surgical Procedures; Surgical Flaps; Surgical Scars; Treatment Outcome; Quality of Life; Breast Conservation Therapy
8.  Path-length-multiplexed scattering-angle-diverse optical coherence tomography for retinal imaging 
Optics letters  2013;38(21):4374-4377.
A low-resolution path-length-multiplexed scattering angle diverse optical coherence tomography (PM-SAD-OCT) is constructed to investigate the scattering properties of the retinal nerve fiber layer (RNFL). Low-resolution PM-SADOCT retinal images acquired from a healthy human subject show the variation of RNFL scattering properties at retinal locations around the optic nerve head. The results are consistent with known retinal ganglion cell neural anatomy and principles of light scattering. Application of PM-SAD-OCT may provide potentially valuable diagnostic information for clinical retinal imaging.
PMCID: PMC3903005  PMID: 24177097
9.  Biomedical imaging informatics in the era of precision medicine: progress, challenges, and opportunities 
doi:10.1136/amiajnl-2013-002315
PMCID: PMC3822124  PMID: 24114330
Imaging Informatics; Image Analysis; Computer Aided Diagnosis; Precision Medicine; Whole Slide Imaging; Image Annotation
10.  Assessment of Breast Aesthetics 
Plastic and reconstructive surgery  2008;121(4):186e-194e.
A good aesthetic outcome is an important endpoint of breast cancer treatment. Subjective ratings, direct physical measurements, measurements on photographs, and assessment by three-dimensional imaging are reviewed and future directions in aesthetic outcome measurements are discussed. Qualitative, subjective scales have frequently been used to assess aesthetic outcomes following breast cancer treatment. However, none of these scales has achieved widespread use because they are typically vague and have low intra- and inter- observer agreement. Anthropometry is not routinely performed because it is impractical to conduct the large studies needed to validate anthropometric measures, i.e., studies in which several observers measure the same subjects multiple times. Quantitative measures based on digital/digitized photographs have yielded acceptable results but have some limitations. Three-dimensional imaging has the potential to enable consistent, objective assessment of breast appearance, including properties, such as volume, that are not available from two-dimensional images. However, further work is needed to define 3D measures of aesthetic properties and how they should be interpreted.
doi:10.1097/01.prs.0000304593.74672.b8
PMCID: PMC3097998  PMID: 18349598
Aesthetics; Breast Neoplasm; Esthetics; Mastectomy; Outcomes; Prostheses and Implants; Reconstructive Surgical Procedures; Surgical Flaps; Treatment Outcome; Quality of Life; Breast Conservation Therapy
11.  Toward Quantifying the Aesthetic Outcomes of Breast Cancer Treatment: Comparison of Clinical Photography and Colorimetry 
Rationale, aims and objectives
Scarring is a significant cause of dissatisfaction for women who undergo breast surgery. Scar tissue may be clinically distinguished from normal skin by aberrant color, rough surface texture, increased thickness (hypertrophy), and firmness. Colorimeters or spectrophotometers can be used to quantitatively assess scar color, but they require direct patient interaction and can cost thousands of dollars By comparison, digital photography is already in widespread use to document clinical outcomes and requires less patient interaction. Thus, assessment of scar coloration by digital photography is an attractive alternative. The goal of this study was to compare color measurements obtained by digital photography and colorimetry.
Method
Agreement between photographic and colorimetric measurements of color were evaluated. Experimental conditions were controlled by performing measurements on artificial scars created by a makeup artist. The colorimetric measurements of the artificial scars were compared to those reported in the literature for real scars in order to confirm the validity of this approach. We assessed the agreement between the colorimetric and photographic measurements of color using a hypothesis test for equivalence, the intra-class correlation coefficient (ICC), and the Bland-Altman method.
Results
Overall, good agreement was obtained for three parameters (L*a*b*) measured by colorimetry and photography from the results of three statistical analyses.
Conclusion
Color measurements obtained by digital photography were equivalent to those obtained using colorimetry. Thus, digital photography is a reliable, cost-effective measurement method of skin color and should be further investigated for quantitative analysis of surgical outcomes.
doi:10.1111/j.1365-2753.2008.00945.x
PMCID: PMC3072466  PMID: 19239578
Aesthetics; Breast Neoplasm; Clinical Photography; Reconstructive Surgical Procedures; Surgical Scars; Treatment Outcome
12.  A Research Agenda for Appearance Changes Due to Breast Cancer Treatment 
Breast cancer is one of the most prevalent forms of cancer in the US. It is estimated that more than 180,000 American women will be diagnosed with invasive breast cancer in 2008. Fortunately, the survival rate is relatively high and continually increasing due to improved detection techniques and treatment methods. However, maintaining quality of life is a factor often under emphasized for breast cancer survivors. Breast cancer treatments are invasive and can lead to deformation of the breast. Breast reconstruction is important for restoring the survivor’s appearance. However, more work is needed to develop technologies for quantifying surgical outcomes and understanding women’s perceptions of changes in their appearance. A method for objectively measuring breast anatomy is needed in order to help both the breast cancer survivors and their surgeons take expected changes to the survivor’s appearance into account when considering various treatment options. In the future, augmented reality tools could help surgeons reconstruct a survivor’s breasts to match her preferences as much as possible.
PMCID: PMC3085417  PMID: 21655363
breast cancer; 3D imaging of breast; computer-assisted image analysis; quality of life
13.  Computer-Aided Detection of Breast Cancer – Have All Bases Been Covered? 
The use of computer-aided detection (CAD) systems in mammography has been the subject of intense research for many years. These systems have been developed with the aim of helping radiologists to detect signs of breast cancer. However, the effectiveness of CAD systems in practice has sparked recent debate. In this commentary, we argue that computer-aided detection will become an increasingly important tool for radiologists in the early detection of breast cancer, but there are some important issues that need to be given greater focus in designing CAD systems if they are to reach their full potential.
PMCID: PMC3085409  PMID: 21655364
computer-aided detection; breast cancer; mammography; radiology
14.  Parametric Power Spectral Density Analysis of Noise from Instrumentation in MALDI TOF Mass Spectrometry 
Cancer Informatics  2007;3:219-230.
Noise in mass spectrometry can interfere with identification of the biochemical substances in the sample. For example, the electric motors and circuits inside the mass spectrometer or in nearby equipment generate random noise that may distort the true shape of mass spectra. This paper presents a stochastic signal processing approach to analyzing noise from electrical noise sources (i.e., noise from instrumentation) in MALDI TOF mass spectrometry. Noise from instrumentation was hypothesized to be a mixture of thermal noise, 1/f noise, and electric or magnetic interference in the instrument. Parametric power spectral density estimation was conducted to derive the power distribution of noise from instrumentation with respect to frequencies. As expected, the experimental results show that noise from instrumentation contains 1/f noise and prominent periodic components in addition to thermal noise. These periodic components imply that the mass spectrometers used in this study may not be completely shielded from the internal or external electrical noise sources. However, according to a simulation study of human plasma mass spectra, noise from instrumentation does not seem to affect mass spectra significantly. In conclusion, analysis of noise from instrumentation using stochastic signal processing here provides an intuitive perspective on how to quantify noise in mass spectrometry through spectral modeling.
PMCID: PMC2675828  PMID: 19455245
Mass; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Noise; Artifacts; Fourier Analysis; Signal Processing; Computer-Assisted; Computer Simulation; Models; Computer
15.  Monte Carlo lookup table-based inverse model for extracting optical properties from tissue-simulating phantoms using diffuse reflectance spectroscopy 
Journal of Biomedical Optics  2013;18(3):037003.
Abstract.
We present a Monte Carlo lookup table (MCLUT)-based inverse model for extracting optical properties from tissue-simulating phantoms. This model is valid for close source-detector separation and highly absorbing tissues. The MCLUT is based entirely on Monte Carlo simulation, which was implemented using a graphics processing unit. We used tissue-simulating phantoms to determine the accuracy of the MCLUT inverse model. Our results show strong agreement between extracted and expected optical properties, with errors rate of 1.74% for extracted reduced scattering values, 0.74% for extracted absorption values, and 2.42% for extracted hemoglobin concentration values.
doi:10.1117/1.JBO.18.3.037003
PMCID: PMC3584151  PMID: 23455965
optical properties; diffuse reflectance spectroscopy; graphical processing unit; lookup table; inverse model
16.  Verification of a two-layer inverse Monte Carlo absorption model using multiple source-detector separation diffuse reflectance spectroscopy 
Biomedical Optics Express  2013;5(1):40-53.
A two-layer Monte Carlo lookup table-based inverse model is validated with two-layered phantoms across physiologically relevant optical property ranges. Reflectance data for source-detector separations of 370 μm and 740 μm were collected from these two-layered phantoms and top layer thickness, reduced scattering coefficient and the top and bottom layer absorption coefficients were extracted using the inverse model and compared to the known values. The results of the phantom verification show that this method is able to accurately extract top layer thickness and scattering when the top layer thickness ranges from 0 to 550 μm. In this range, top layer thicknesses were measured with an average error of 10% and the reduced scattering coefficient was measured with an average error of 15%. The accuracy of top and bottom layer absorption coefficient measurements was found to be highly dependent on top layer thickness, which agrees with physical expectation; however, within appropriate thickness ranges, the error for absorption properties varies from 12–25%.
doi:10.1364/BOE.5.000040
PMCID: PMC3891344  PMID: 24466475
(170.6510) Spectroscopy, tissue diagnostics; (100.3190) Inverse problems
17.  Automated Identification of Fiducial Points on 3D Torso Images 
Breast reconstruction is an important part of the breast cancer treatment process for many women. Recently, 2D and 3D images have been used by plastic surgeons for evaluating surgical outcomes. Distances between different fiducial points are frequently used as quantitative measures for characterizing breast morphology. Fiducial points can be directly marked on subjects for direct anthropometry, or can be manually marked on images. This paper introduces novel algorithms to automate the identification of fiducial points in 3D images. Automating the process will make measurements of breast morphology more reliable, reducing the inter- and intra-observer bias. Algorithms to identify three fiducial points, the nipples, sternal notch, and umbilicus, are described. The algorithms used for localization of these fiducial points are formulated using a combination of surface curvature and 2D color information. Comparison of the 3D co-ordinates of automatically detected fiducial points and those identified manually, and geodesic distances between the fiducial points are used to validate algorithm performance. The algorithms reliably identified the location of all three of the fiducial points. We dedicate this article to our late colleague and friend, Dr. Elisabeth K. Beahm. Elisabeth was both a talented plastic surgeon and physician-scientist; we deeply miss her insight and her fellowship.
doi:10.4137/BECB.S11800
PMCID: PMC4147764  PMID: 25288903
3D surface mesh; breast reconstruction; curvature; breast morphology; landmark detection
18.  Thickness, Phase Retardation, Birefringence, and Reflectance of the Retinal Nerve Fiber Layer in Normal and Glaucomatous Non-Human Primates 
Purpose.
We identified candidate optical coherence tomography (OCT) markers for early glaucoma diagnosis. Time variation of retinal nerve fiber layer (RNFL) thickness, phase retardation, birefringence, and reflectance using polarization sensitive optical coherence tomography (PS-OCT) were measured in three non-human primates with induced glaucoma in one eye. We characterized time variation of RNFL thickness, phase retardation, birefringence, and reflectance with elevated intraocular pressure (IOP).
Methods.
One eye of each of three non-human primates was laser treated to increase IOP. Each primate was followed for a 30-week period. PS-OCT measurements were recorded at weekly intervals. Reflectance index (RI) is introduced to characterize RNFL reflectance. Associations between elevated IOP and RNFL thickness, phase retardation, birefringence, and reflectance were characterized in seven regions (entire retina, inner and outer rings, and nasal, temporal, superior and inferior quadrants) by linear and non-linear mixed-effects models.
Results.
Elevated IOP was achieved in three non-human primate eyes with an average increase of 13 mm Hg over the study period. Elevated IOP was associated with decreased RNFL thickness in the nasal region (P = 0.0002), decreased RNFL phase retardation in the superior (P = 0.046) and inferior (P = 0.021) regions, decreased RNFL birefringence in the nasal (P = 0.002) and inferior (P = 0.029) regions, and loss of RNFL reflectance in the outer rings (P = 0.018). When averaged over the entire retinal area, only RNFL reflectance showed a significant decrease (P = 0.028).
Conclusions.
Of the measured parameters, decreased RNFL reflectance was the most robust correlate with glaucomatous damage. Candidate cellular mechanisms are considered for decreased RNFL reflectance, including mitochondrial dysfunction and retinal ganglion cell apoptosis.
Measured time variation of retinal nerve fiber layer (RNFL) thickness, phase retardation, birefringence, and reflectance using polarization sensitive optical coherence tomography (PS-OCT) in three non-human primates with induced glaucoma in one eye over the course of 30 weeks.
doi:10.1167/iovs.11-9130
PMCID: PMC3394663  PMID: 22570345
19.  A Pilot Study on Using Eye Tracking to Understand Assessment of Surgical Outcomes from Clinical Photography 
Journal of Digital Imaging  2010;24(5):778-786.
Appearance changes resulting from breast cancer treatment impact the quality of life of breast cancer survivors, but current approaches to evaluating breast characteristics are very limited. It is challenging, even for experienced plastic surgeons, to describe how different aspects of breast morphology impact overall assessment of esthetics. Moreover, it is difficult to describe what they are looking for in a manner that facilitates quantification. The goal of this study is to assess the potential of using eye-tracking technology to understand how plastic surgeons assess breast morphology by recording their gaze path while they rate physical characteristics of the breasts, e.g., symmetry, based on clinical photographs. In this study, dwell time, transition frequency, dwell sequence conditional probabilities, and dwell sequence joint probabilities were analyzed across photographic poses and three observers. Dwell-time analysis showed that all three surgeons spent the majority of their time on the anterior–posterior (AP) views. Similarly, transition frequency analysis between regions showed that there were substantially more transitions between the breast regions in the AP view, relative to the number of transitions between other views. The results of both the conditional and joint probability analyses between the breast regions showed that the highest probabilities of transitions were observed between the breast regions in the AP view (APRB, APLB) followed by the oblique views and the lateral views to complete evaluation of breast surgical outcomes.
doi:10.1007/s10278-010-9338-x
PMCID: PMC3180533  PMID: 20852914
Breast neoplasm; Eye movements; Biomedical image analysis; Decision support; Evaluation research
20.  A Novel Quantitative Measure of Breast Curvature Based on Catenary 
Quantitative, objective measurements of breast curvature computed from clinical photographs could be used to investigate factors that impact reconstruction and facilitate surgical planning. This paper introduces a novel quantitative measure of breast curvature based on catenary. A catenary curve is used to approximate the overall curvature of the breast contour, and the curvature measure is extracted from the catenary curve. The catenary curve was verified by comparing its length, the area enclosed by the curve, and the curvature measure from the catenary curve to those from manual tracings of the breast contour. The evaluation of the proposed analysis employed untreated and postoperative clinical photographs of women who were undergoing tissue expander/implant (TE/Implant) reconstruction. Logistic regression models were developed to distinguish between the curvature of breasts undergoing TE/Implant reconstruction and that of untreated breasts based on the curvature measure and patient variables (age and body mass index). The relationships between the curvature measures of untreated breasts and patient variables were also investigated. The catenary curve approximates breast curvature reliably. The curvature measure contains useful information for quantifying the curvature differences between breasts undergoing TE/Implant reconstruction and untreated breasts, and identifying the effect of patient variables on the breast shape.
doi:10.1109/TBME.2012.2184541
PMCID: PMC3334380  PMID: 22271826
Breast cancer; breast curvature; breast reconstruction; catenary; digital photographs
21.  Principal-Oscillation-Pattern Analysis of Gene Expression 
PLoS ONE  2012;7(1):e28805.
Principal-oscillation-pattern (POP) analysis is a multivariate and systematic technique for identifying the dynamic characteristics of a system from time-series data. In this study, we demonstrate the first application of POP analysis to genome-wide time-series gene-expression data. We use POP analysis to infer oscillation patterns in gene expression. Typically, a genomic system matrix cannot be directly estimated because the number of genes is usually much larger than the number of time points in a genomic study. Thus, we first identify the POPs of the eigen-genomic system that consists of the first few significant eigengenes obtained by singular value decomposition. By using the linear relationship between eigengenes and genes, we then infer the POPs of the genes. Both simulation data and real-world data are used in this study to demonstrate the applicability of POP analysis to genomic data. We show that POP analysis not only compares favorably with experiments and existing computational methods, but that it also provides complementary information relative to other approaches.
doi:10.1371/journal.pone.0028805
PMCID: PMC3254616  PMID: 22253697
22.  Evaluation of Stylus for Radiographic Image Annotation 
Journal of Digital Imaging  2009;23(6):701-705.
We evaluated the use of a stylus as a computer interface for radiographic image annotation. Our case study concerned the annotation of spiculated lesions on mammograms. Three experienced radiologists annotated 20 mammograms depicting spiculated lesions. We evaluated the interobserver agreement in annotations marked with a stylus versus those marked with a mouse using the intraclass correlation coefficient. Better agreement in annotating spicule width was observed with the stylus, suggesting that it is easier to accurately annotate subtle regions on an image using a stylus.
doi:10.1007/s10278-009-9232-6
PMCID: PMC3046686  PMID: 19707827
Radiography; mammography; imaging informatics; image display
23.  3D Symmetry Measure Invariant to Subject Pose During Image Acquisition 
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.
doi:10.4137/BCBCR.S7140
PMCID: PMC3140267  PMID: 21792310
three-dimensional; stereophotogrammetry; subject pose; validation; breast; symmetry; surgical planning; pBRA
24.  Validation of Stereophotogrammetry of the Human Torso 
The objective of this study was to determine if measurements of breast morphology computed from three-dimensional (3D) stereophotogrammetry are equivalent to traditional anthropometric measurements obtained directly on a subject using a tape measure. 3D torso images of 23 women ranged in age from 36 to 63 who underwent or were scheduled for breast reconstruction surgery were obtained using a 3dMD torso system (3Q Technologies Inc., Atlanta, GA). Two different types (contoured and line-of-sight distances) of a total of nine distances were computed from 3D images of each participant. Each participant was photographed twice, first without fiducial points marked (referred to as unmarked image) and second with fiducial points marked prior to imaging (referred to as marked image). Stereophotogrammetry was compared to traditional direct anthropometry, in which measurements were taken with a tape measure on participants. Three statistical analyses were used to evaluate the agreement between stereophotogrammetry and direct anthropometry. Seven out of nine distances showed excellent agreement between stereophotogrammetry and direct anthropometry (both marked and unmarked images). In addition, stereophotogrammetry from the unmarked image was equivalent to that of the marked image (both line-of-sight and contoured distances). A lower level of agreement was observed for some measures because of difficulty in localizing more vaguely defined fiducial points, such as lowest visible point of breast mound, and inability of the imaging system in capturing areas obscured by the breast, such as the inframammary fold. Stereophotogrammetry from 3D images obtained from the 3dMD torso system is effective for quantifying breast morphology. Tools for surgical planning and evaluation based on stereophotogrammetry have the potential to improve breast surgery outcomes.
doi:10.4137/BCBCR.S6352
PMCID: PMC3076012  PMID: 21494398
three-dimensional; anthropometry; validation; breast; photogrammetry; stereophotogrammetry; surgical planning
25.  The Relationship between Retinal Ganglion Cell Axon Constituents and Retinal Nerve Fiber Layer Birefringence in the Primate 
Purpose
To determine the degree of correlation between spatial characteristics of the retinal nerve fiber layer (RNFL) birefringence (ΔnRNFL) surrounding the optic nerve head (ONH) with the corresponding anatomy of retinal ganglion cell (RGC) axons and their respective organelles.
Methods
RNFL phase retardation per unit depth (PR/UD, proportional to ΔnRNFL) was measured in two cynomolgus monkeys using enhanced polarization-sensitive optical coherence tomography (EPS-OCT). The monkeys were perfused with glutaraldehyde and eyes were enucleated and prepared for transmission electron microscopy (TEM) histological analysis. Morphological measurements from TEM images were used to estimate values of neurotubule density (ρRNFL), axoplasmic area (Ax) mode, axon area (Aa) mode, slope (u) of neurotubule number versus axoplasmic area [neurotubule packing density], fractional area of axoplasm in the nerve fiber bundle (f), mitochondrial fractional area in the nerve fiber bundle (xm), mitochondriated axon profile fraction (mp), and length of axonal membrane profiles per unit nerve fiber bundle area (Lam/Ab). Registered PR/UD and morphological parameters from corresponding angular sections were then correlated using Pearson’s correlation and multi-level models.
Results
In one eye, there was a statistically significant correlation between PR/UD and ρRNFL (r = 0.67, P =0.005) and between PR/UD and neurotubule packing density (r = 0.70, P = 0.002). Correlation coefficients of r = 0.81 (P=0.01) and r = 0.50 (P = 0.05) were observed between PR/UD and (Ax) mode for each respective subject.
Conclusion
Neurotubules are the primary source of birefringence in the RNFL of the primate retina.
doi:10.1167/iovs.08-3263
PMCID: PMC2783205  PMID: 19494208

Results 1-25 (32)