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1.  Inverse consistent non-rigid image registration based on robust point set matching 
BioMedical Engineering OnLine  2014;13(Suppl 2):S2.
Background
Robust point matching (RPM) has been extensively used in non-rigid registration of images to robustly register two sets of image points. However, except for the location at control points, RPM cannot estimate the consistent correspondence between two images because RPM is a unidirectional image matching approach. Therefore, it is an important issue to make an improvement in image registration based on RPM.
Methods
In our work, a consistent image registration approach based on the point sets matching is proposed to incorporate the property of inverse consistency and improve registration accuracy. Instead of only estimating the forward transformation between the source point sets and the target point sets in state-of-the-art RPM algorithms, the forward and backward transformations between two point sets are estimated concurrently in our algorithm. The inverse consistency constraints are introduced to the cost function of RPM and the fuzzy correspondences between two point sets are estimated based on both the forward and backward transformations simultaneously. A modified consistent landmark thin-plate spline registration is discussed in detail to find the forward and backward transformations during the optimization of RPM. The similarity of image content is also incorporated into point matching in order to improve image matching.
Results
Synthetic data sets, medical images are employed to demonstrate and validate the performance of our approach. The inverse consistent errors of our algorithm are smaller than RPM. Especially, the topology of transformations is preserved well for our algorithm for the large deformation between point sets. Moreover, the distance errors of our algorithm are similar to that of RPM, and they maintain a downward trend as whole, which demonstrates the convergence of our algorithm. The registration errors for image registrations are evaluated also. Again, our algorithm achieves the lower registration errors in same iteration number. The determinant of the Jacobian matrix of the deformation field is used to analyse the smoothness of the forward and backward transformations. The forward and backward transformations estimated by our algorithm are smooth for small deformation. For registration of lung slices and individual brain slices, large or small determinant of the Jacobian matrix of the deformation fields are observed.
Conclusions
Results indicate the improvement of the proposed algorithm in bi-directional image registration and the decrease of the inverse consistent errors of the forward and the reverse transformations between two images.
doi:10.1186/1475-925X-13-S2-S2
PMCID: PMC4304244  PMID: 25559889
Consistent image registration; Robust point matching; Correspondence; Forward transformation; Backward transformation
2.  Factors associated with willingness to participate in free HIV test among general residents in Heilongjiang, Northeast China 
BMC Infectious Diseases  2012;12:256.
Background
The human immunodeficiency virus (HIV) is spreading from high-risk groups, such as men who have sex with men (MSM) and sex workers, to the general population in China. This study examined the willingness of general residents in Heilongjiang, Northeast China, to participate in free HIV testing in the nearest health care setting, and the factors that may affect participation, including demographic characteristics, HIV-related knowledge, and stigma.
Methods
A cross-sectional study was conducted in Heilongjiang Province. All residents aged 15–69 years in two communities in urban areas (September 2007) and four villages in rural areas (April 2008) were recruited using stratified cluster sampling. A total of 4050 residents were interviewed using an anonymous questionnaire. Univariate and multivariate log-binomial regression were used to analyze factors affecting willingness to undergo HIV testing.
Results
The proportions of participants who were willing to participate in free HIV testing was 73.0% in urban residents and 78.8% in rural residents. Multivariate regression analysis among urban participants showed that greater knowledge of HIV transmission misconceptions (relative risk (RR) = 1.02, 95% confidence interval (CI): 1.00–1.04, P = 0.021) and the awareness that an apparently healthy person can be an HIV carrier (RR = 1.12, 95%CI: 1.03–1.21, P = 0.007) was significantly associated with greater willingness to participate in free HIV testing. Among rural participants, greater knowledge of HIV transmission modes (RR = 1.03, 95%CI: 1.01–1.06 P = 0.001) and the awareness that an apparently healthy person can be an HIV carrier (RR = 1.07; 95%CI: 1.01–1.13 P = 0.019) was significantly associated with greater willingness to participate.
Conclusions
The overall level of willingness to accept free HIV testing is high, and is higher in rural residents than in urban residents in Heilongjiang. knowledge of HIV transmission misconceptions and that an apparently healthy person can be a carrier for HIV were associated with willingness to accept free HIV testing among urban residents, while knowledge of HIV transmission modes and that an apparently healthy person can be a carrier for HIV were associated with willingness to accept free HIV testing among rural residents.
doi:10.1186/1471-2334-12-256
PMCID: PMC3482579  PMID: 23057556
HIV; Knowledge; Public stigma; Willingness; General individuals

Results 1-2 (2)