Development of a fully automatic shape model matching (FASMM) system to derive statistical shape models from radiographs: application to the accurate capture and global representation of proximal femur shape

Lindner, Claudia; Thiagarajah, S; Wilkinson, J. Mark; Wallis, Gillian A.; Cootes, Timothy F.

doi:10.1016/j.joca.2013.08.008

Cited by 34 publications

(30 citation statements)

References 20 publications

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“…As the field moves toward more automated methods 16 , it will be possible to generate shape data on larger populations. Even in this setting, these methods provide a much more efficient use of the data and will be preferable to conventional methods.…”

Section: Discussionmentioning

confidence: 99%

Novel statistical methodology reveals that hip shape is associated with incident radiographic hip osteoarthritis among African American women

Marron

Schwartz

et al. 2016

Osteoarthritis and Cartilage

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Introduction Hip shape is a risk factor for the development of hip osteoarthritis (OA), and current methods to assess hip shape from radiographs are limited; therefore this study explored current and novel methods to assess hip shape. Methods Data from a prior case-control study nested in the Johnston County OA Project were used, including 382 hips (from 342 individuals). Hips were classified by radiographic hip OA (RHOA) status as RHOA cases (baseline Kellgren Lawrence grade [KLG] 0 or 1, follow-up [mean 6 years] KLG ≥ 2) or controls (KLG=0 or 1 at both baseline and follow-up). Proximal femur shape was assessed using a 60-point model as previously described. The current analysis explored commonly used principal component analysis (PCA), as well as novel statistical methodologies suited to high dimension low sample size settings (Distance Weighted Discrimination [DWD] and Distance Projection Permutation [DiProPerm] hypothesis testing) to assess differences between cases and controls. Results Using these novel methodologies, we were able to better characterize morphologic differences by sex and race. In particular, the proximal femurs of African American women demonstrated significantly different shapes between cases and controls, implying an important role for sex and race in the development of RHOA. Notably, discrimination was improved with the use of DWD and DiProPerm compared to PCA. Conclusions DWD with DiProPerm significance testing provides improved discrimination of variation in hip morphology between groups, and enables subgroup analyses even under small sample sizes.

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Section: Discussionmentioning

confidence: 99%

Novel statistical methodology reveals that hip shape is associated with incident radiographic hip osteoarthritis among African American women

Marron

Schwartz

et al. 2016

Osteoarthritis and Cartilage

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“…As previously described [20], the system was trained on 1105 AP pelvic radiographs from subjects recruited in Stage 2 of The arcOGEN Consortium study [23]. The FASMM system segments the proximal femur by first detecting it in the radiograph and then outlining its contour using 65 points (see Fig.…”

Section: Methodsmentioning

confidence: 99%

“…As previously described [20], the contour points returned by the FASMM system are used to represent the shape of the proximal femur as an SSM. This provides a global representation of shape rather than reducing shape to a series of linear measurements which enables the analysis of shape variation across datasets.…”

Section: Methodsmentioning

confidence: 99%

“…To analyse the symmetry of the left and right proximal femurs when using conventional hip geometric measurements before and after adjusting for oppositional asymmetric patterns of shape variation, we fully automatically calculated hip geometric measurements from the output of the FASMM as previously described [20]. We obtained the femoral head diameter, neck width, shaft width and neck-shaft angle for both hips of every subject.…”

Section: Methodsmentioning

confidence: 99%

“…The formula for calculating the absolute percent asymmetry (AA%) for each measurement and every subject was:

AA% = \frac{(||, m_{l} - m_{r})}{μ} x 100

where m l and m r are the measurement values for the left and right sides of the subject and μ is the mean of the left and right measurement values for that subject. All calculations were made using custom code developed in Matlab R2010a (see [20]). …”

Section: Methodsmentioning

confidence: 99%

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Increasing shape modelling accuracy by adjusting for subject positioning: An application to the analysis of radiographic proximal femur symmetry using data from the Osteoarthritis Initiative

Lindner

Wallis

Cootes

2014

Bone

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In total hip arthroplasty, the shape of the contra-lateral femur frequently serves as a template for preoperative planning. Previous research on contra-lateral femoral symmetry has been based on conventional hip geometric measurements (which reduce shape to a series of linear measurements) and did not take the effect of subject positioning on radiographic femur shape into account. The aim of this study was to analyse proximal femur symmetry based on statistical shape models (SSMs) which quantify global femoral shape while also adjusting for differences in subject positioning during image acquisition. We applied our recently developed fully automatic shape model matching (FASMM) system to automatically segment the proximal femur from AP pelvic radiographs to generate SSMs of the proximal femurs of 1258 Caucasian females (mean age: 61.3 SD = 9.0). We used a combined SSM (capturing the left and right femurs) to identify and adjust for shape variation attributable to subject positioning as well as a single SSM (including all femurs as left femurs) to analyse proximal femur symmetry. We also calculated conventional hip geometric measurements (head diameter, neck width, shaft width and neck-shaft angle) using the output of the FASMM system. The combined SSM revealed two modes that were clearly attributable to subject positioning. The average difference (mean point-to-curve distance) between left and right femur shape was 1.0 mm before and 0.8 mm after adjusting for these two modes. The automatic calculation of conventional hip geometric measurements after adjustment gave an average absolute percent asymmetry of within 3.1% and an average absolute difference of within 1.1 mm or 2.9° for all measurements. We conclude that (i) for Caucasian females the global shape of the right and left proximal femurs is symmetric without isolated locations of asymmetry; (ii) a combined left–right SSM can be used to adjust for radiographic shape variation due to subject positioning; and (iii) adjusting for subject positioning increases the accuracy of predicting the shape of the contra-lateral hip.

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Investigation of Association Between Hip Osteoarthritis Susceptibility Loci and Radiographic Proximal Femur Shape

Lindner

Thiagarajah

Wilkinson

et al. 2015

Arthritis & Rheumatology

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ObjectiveTo test whether previously reported hip morphology or osteoarthritis (OA) susceptibility loci are associated with proximal femur shape as represented by statistical shape model (SSM) modes and as univariate or multivariate quantitative traits.MethodsWe used pelvic radiographs and genotype data from 929 subjects with unilateral hip OA who had been recruited previously for the Arthritis Research UK Osteoarthritis Genetics Consortium genome‐wide association study. We built 3 SSMs capturing the shape variation of the OA‐unaffected proximal femur in the entire mixed‐sex cohort and for male/female‐stratified cohorts. We selected 41 candidate single‐nucleotide polymorphisms (SNPs) previously reported as being associated with hip morphology (for replication analysis) or OA (for discovery analysis) and for which genotype data were available. We performed 2 types of analysis for genotype–phenotype associations between these SNPs and the modes of the SSMs: 1) a univariate analysis using individual SSM modes and 2) a multivariate analysis using combinations of SSM modes.ResultsThe univariate analysis identified association between rs4836732 (within the ASTN2 gene) and mode 5 of the female SSM (P = 0.0016) and between rs6976 (within the GLT8D1 gene) and mode 7 of the mixed‐sex SSM (P = 0.0003). The multivariate analysis identified association between rs5009270 (near the IFRD1 gene) and a combination of modes 3, 4, and 9 of the mixed‐sex SSM (P = 0.0004). Evidence of associations remained significant following adjustment for multiple testing. All 3 SNPs had previously been associated with hip OA.ConclusionThese de novo findings suggest that rs4836732, rs6976, and rs5009270 may contribute to hip OA susceptibility by altering proximal femur shape.

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Development of a fully automatic shape model matching (FASMM) system to derive statistical shape models from radiographs: application to the accurate capture and global representation of proximal femur shape

Cited by 34 publications

References 20 publications

Novel statistical methodology reveals that hip shape is associated with incident radiographic hip osteoarthritis among African American women

Novel statistical methodology reveals that hip shape is associated with incident radiographic hip osteoarthritis among African American women

Increasing shape modelling accuracy by adjusting for subject positioning: An application to the analysis of radiographic proximal femur symmetry using data from the Osteoarthritis Initiative

Investigation of Association Between Hip Osteoarthritis Susceptibility Loci and Radiographic Proximal Femur Shape

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