http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Thu, 16 May 2013 11:43:00 +0000 http://www.hindawi.com/journals/ijbi/2013/540571/ The Finite Element Method is a well-known technique, being extensively applied in different areas. Studies using the Finite Element Method (FEM) are targeted to improve cardiac ablation procedures. For such simulations, the finite element meshes should consider the size and histological features of the target structures. However, it is possible to verify that some methods or tools used to generate meshes of human body structures are still limited, due to nondetailed models, nontrivial preprocessing, or mainly limitation in the use condition. In this paper, alternatives are demonstrated to solid modeling and automatic generation of highly refined tetrahedral meshes, with quality compatible with other studies focused on mesh generation. The innovations presented here are strategies to integrate Open Source Software (OSS). The chosen techniques and strategies are presented and discussed, considering cardiac structures as a first application context. E. Pavarino, L. A. Neves, J. M. Machado, M. F. de Godoy, Y. Shiyou, J. C. Momente, G. F. D. Zafalon, A. R. Pinto, and C. R. Valêncio Copyright © 2013 E. Pavarino et al. All rights reserved. Wed, 03 Apr 2013 09:03:04 +0000 http://www.hindawi.com/journals/ijbi/2013/205494/ This paper presents recent advances in the use of diffeomorphic active shapes which incorporate the conservation laws of large deformation diffeomorphic metric mapping. The equations of evolution satisfying the conservation law are geodesics under the diffeomorphism metric and therefore termed geodesically controlled diffeomorphic active shapes (GDAS). Our principal application in this paper is on robust diffeomorphic mapping methods based on parameterized surface representations of subcortical template structures. Our parametrization of the GDAS evolution is via the initial momentum representation in the tangent space of the template surface. The dimension of this representation is constrained using principal component analysis generated from training samples. In this work, we seek to use template surfaces to generate segmentations of the hippocampus with three data attachment terms: surface matching, landmark matching, and inside-outside modeling from grayscale T1 MR imaging data. This is formulated as an energy minimization problem, where energy describes shape variability and data attachment accuracy, and we derive a variational solution. A gradient descent strategy is employed in the numerical optimization. For the landmark matching case, we demonstrate the robustness of this algorithm as applied to the workflow of a large neuroanatomical study by comparing to an existing diffeomorphic landmark matching algorithm. Daniel J. Tward, Jun Ma, Michael I. Miller, and Laurent Younes Copyright © 2013 Daniel J. Tward et al. All rights reserved. Thu, 28 Mar 2013 14:37:24 +0000 http://www.hindawi.com/journals/ijbi/2013/343180/ Nonlinear microwave imaging heavily relies on an accurate numerical electromagnetic model of the antenna system. The model is used to simulate scattering data that is compared to its measured counterpart in order to reconstruct the image. In this paper an antenna system immersed in water is used to image different canonical objects in order to investigate the implication of modeling errors on the final reconstruction using a time domain-based iterative inverse reconstruction algorithm and three-dimensional FDTD modeling. With the test objects immersed in a background of air and tap water, respectively, we have studied the impact of antenna modeling errors, errors in the modeling of the background media, and made a comparison with a two-dimensional version of the algorithm. In conclusion even small modeling errors in the antennas can significantly alter the reconstructed image. Since the image reconstruction procedure is highly nonlinear general conclusions are very difficult to make. In our case it means that with the antenna system immersed in water and using our present FDTD-based electromagnetic model the imaging results are improved if refraining from modeling the water-wall-air interface and instead just use a homogeneous background of water in the model. Andreas Fhager, Shantanu K. Padhi, Mikael Persson, and John Howard Copyright © 2013 Andreas Fhager et al. All rights reserved. Mon, 11 Mar 2013 08:27:23 +0000 http://www.hindawi.com/journals/ijbi/2013/658583/ This work investigates the possibilities of applying high-angular-resolution-diffusion-imaging- (HARDI-) based methods in a clinical setting by investigating the performance of non-Gaussian diffusion probability density function (PDF) estimation for a range of b-values and diffusion gradient direction tables. It does so at realistic SNR levels achievable in limited time on a high-performance 3T system for the whole human brain in vivo. We use both computational simulations and in vivo brain scans to quantify the angular resolution of two selected reconstruction methods: Q-ball imaging and the diffusion orientation transform. We propose a new analytical solution to the ODF derived from the DOT. Both techniques are analytical decomposition approaches that require identical acquisition and modest postprocessing times and, given the proposed modifications of the DOT, can be analyzed in a similar fashion. We find that an optimal HARDI protocol given a stringent time constraint (<10 min) combines a moderate b-value (around 2000 s/mm2) with a relatively low number of acquired directions (>48). Our findings generalize to other methods and additional improvements in MR acquisition techniques. V. Prčkovska, H. C. Achterberg, M. Bastiani, P. Pullens, E. Balmashnova, B. M. ter Haar Romeny, A. Vilanova, and A. Roebroeck Copyright © 2013 V. Prčkovska et al. All rights reserved. Thu, 28 Feb 2013 09:25:05 +0000 http://www.hindawi.com/journals/ijbi/2013/618561/ Ayman El-Baz, Garth M. Beache, Georgy Gimel'farb, Kenji Suzuki, and Kazunori Okada Copyright © 2013 Ayman El-Baz et al. All rights reserved. Tue, 26 Feb 2013 09:47:16 +0000 http://www.hindawi.com/journals/ijbi/2013/230487/ Breast cancer is a major cause of cancer death in women where early detection and accurate assessment of therapy response can improve clinical outcomes. Molecular imaging, which includes PET, SPECT, MRI, and optical modalities, provides noninvasive means of detecting biological processes and molecular events in vivo. Molecular imaging has the potential to enhance our understanding of breast cancer biology and effects of drug action during both preclinical and clinical phases of drug development. This has led to the identification of many molecular imaging probes for key processes in breast cancer. Hormone receptors, growth factor receptor, and angiogenic factors, such as ER, PR, HER2, and VEGFR, have been adopted as imaging targets to detect and stage the breast cancer and to monitor the treatment efficacy. Receptor imaging probes are usually composed of targeting moiety attached to a signaling component such as a radionuclide that can be detected using dedicated instruments. Current molecular imaging probes involved in breast cancer diagnosis and therapy evaluation are reviewed, and future of molecular imaging for the preclinical and clinical is explained. Qingqing Meng and Zheng Li Copyright © 2013 Qingqing Meng and Zheng Li. All rights reserved. Thu, 21 Feb 2013 19:32:56 +0000 http://www.hindawi.com/journals/ijbi/2013/849363/ The acquisition of high angular resolution diffusion MRI is particularly long and subject motion can become an issue. The orientation distribution function (ODF) can be reconstructed online incrementally from diffusion-weighted MRI with a Kalman filtering framework. This online reconstruction provides real-time feedback throughout the acquisition process. In this article, the Kalman filter is first adapted to the reconstruction of the ODF in constant solid angle. Then, a method called STAR (STatistical Analysis of Residuals) is presented and applied to the online detection of motion in high angular resolution diffusion images. Compared to existing techniques, this method is image based and is built on top of a Kalman filter. Therefore, it introduces no additional scan time and does not require additional hardware. The performance of STAR is tested on simulated and real data and compared to the classical generalized likelihood ratio test. Successful detection of small motion is reported (rotation under 2°) with no delay and robustness to noise. Emmanuel Caruyer, Iman Aganj, Christophe Lenglet, Guillermo Sapiro, and Rachid Deriche Copyright © 2013 Emmanuel Caruyer et al. All rights reserved. Tue, 12 Feb 2013 08:01:22 +0000 http://www.hindawi.com/journals/ijbi/2013/517632/ Automatic detection of lung nodules is an important problem in computer analysis of chest radiographs. In this paper, we propose a novel algorithm for isolating lung abnormalities (nodules) from spiral chest low-dose CT (LDCT) scans. The proposed algorithm consists of three main steps. The first step isolates the lung nodules, arteries, veins, bronchi, and bronchioles from the surrounding anatomical structures. The second step detects lung nodules using deformable 3D and 2D templates describing typical geometry and gray-level distribution within the nodules of the same type. The detection combines the normalized cross-correlation template matching and a genetic optimization algorithm. The final step eliminates the false positive nodules (FPNs) using three features that robustly define the true lung nodules. Experiments with 200 CT data sets show that the proposed approach provided comparable results with respect to the experts. Ayman El-Baz, Ahmed Elnakib, Mohamed Abou El-Ghar, Georgy Gimel'farb, Robert Falk, and Aly Farag Copyright © 2013 Ayman El-Baz et al. All rights reserved. Tue, 05 Feb 2013 10:07:28 +0000 http://www.hindawi.com/journals/ijbi/2013/781603/ For the structure mechanics of human body, it is almost impossible to conduct mechanical experiments. Then the finite element model to simulate mechanical experiments has become an effective tool. By introducing several common methods for constructing a 3D model of cranial cavity, this paper carries out systematically the research on the influence law of cranial cavity deformation. By introducing the new concepts and theory to develop the 3D cranial cavity model with the finite-element method, the cranial cavity deformation process with the changing ICP can be made the proper description and reasonable explanation. It can provide reference for getting cranium biomechanical model quickly and efficiently and lay the foundation for further biomechanical experiments and clinical applications. Xianfang Yue, Li Wang, and Ruonan Wang Copyright © 2013 Xianfang Yue et al. All rights reserved. Wed, 30 Jan 2013 13:27:50 +0000 http://www.hindawi.com/journals/ijbi/2013/696878/ Juan Ruiz-Alzola, Carlos Alberola-López, and Carl-Fredrik Westin Copyright © 2013 Juan Ruiz-Alzola et al. All rights reserved. Tue, 29 Jan 2013 13:41:06 +0000 http://www.hindawi.com/journals/ijbi/2013/942353/ This paper overviews one of the most important, interesting, and challenging problems in oncology, the problem of lung cancer diagnosis. Developing an effective computer-aided diagnosis (CAD) system for lung cancer is of great clinical importance and can increase the patient’s chance of survival. For this reason, CAD systems for lung cancer have been investigated in a huge number of research studies. A typical CAD system for lung cancer diagnosis is composed of four main processing steps: segmentation of the lung fields, detection of nodules inside the lung fields, segmentation of the detected nodules, and diagnosis of the nodules as benign or malignant. This paper overviews the current state-of-the-art techniques that have been developed to implement each of these CAD processing steps. For each technique, various aspects of technical issues, implemented methodologies, training and testing databases, and validation methods, as well as achieved performances, are described. In addition, the paper addresses several challenges that researchers face in each implementation step and outlines the strengths and drawbacks of the existing approaches for lung cancer CAD systems. Ayman El-Baz, Garth M. Beache, Georgy Gimel'farb, Kenji Suzuki, Kazunori Okada, Ahmed Elnakib, Ahmed Soliman, and Behnoush Abdollahi Copyright © 2013 Ayman El-Baz et al. All rights reserved. Mon, 21 Jan 2013 15:31:52 +0000 http://www.hindawi.com/journals/ijbi/2013/759421/ Electrophysiological signals such as the EEG, MEG, or LFPs have been extensively studied over the last decades, and elaborate signal processing algorithms have been developed for their analysis. Many of these methods are based on time-frequency decomposition to account for the signals’ spectral properties while maintaining their temporal dynamics. However, the data typically exhibit intra- and interindividual variability. Existing algorithms often do not take into account this variability, for instance by using fixed frequency bands. This shortcoming has inspired us to develop a new robust and flexible method for time-frequency analysis and signal feature extraction using the novel smooth natural Gaussian extension (snaGe) model. The model is nonlinear, and its parameters are interpretable. We propose an algorithm to derive initial parameters based on dynamic programming for nonlinear fitting and describe an iterative refinement scheme to robustly fit high-order models. We further present distance functions to be able to compare different instances of our model. The method’s functionality and robustness are demonstrated using simulated as well as real data. The snaGe model is a general tool allowing for a wide range of applications in biomedical data analysis. R. Heideklang and G. Ivanova Copyright © 2013 R. Heideklang and G. Ivanova. All rights reserved. Tue, 15 Jan 2013 10:03:16 +0000 http://www.hindawi.com/journals/ijbi/2013/803579/ Hydraphiles are a class of synthetic ion channels that now have a twenty-year history of analysis and success. In early studies, these compounds were rigorously validated in a wide range of in vitro assays including liposomal ion flow detected by NMR or ion-selective electrodes, as well as biophysical experiments in planar bilayers. During the past decade, biological activity was observed for these compounds including toxicity to bacteria, yeast, and mammalian cells due to stress caused by the disruption of ion homeostasis. The channel mechanism was verified in cells using membrane polarity sensitive dyes, as well as patch clamping studies. This body of work has provided a solid foundation with which hydraphiles have recently demonstrated acute biological toxicity in the muscle tissue of living mice, as measured by whole animal fluorescence imaging and histological studies. Here we review the critical structure-activity relationships in the hydraphile family of compounds and the in vitro and in cellulo experiments that have validated their channel behavior. This report culminates with a description of recently reported efforts in which these molecules have demonstrated activity in living mice. Saeedeh Negin, Bryan A. Smith, Alexandra Unger, W. Matthew Leevy, and George W. Gokel Copyright © 2013 Saeedeh Negin et al. All rights reserved. Sun, 30 Dec 2012 17:19:25 +0000 http://www.hindawi.com/journals/ijbi/2012/206214/ Photoacoustic imaging (PAI) has been employed to reconstruct endogenous optical contrast present in tissues. At the cost of longer calculations, a compressive sensing reconstruction scheme can achieve artifact-free imaging with fewer measurements. In this paper, an effective acceleration framework using the alternating direction method (ADM) was proposed for recovering images from limited-view and noisy observations. Results of the simulation demonstrated that the proposed algorithm could perform favorably in comparison to two recently introduced algorithms in computational efficiency and data fidelity. In particular, it ran considerably faster than these two methods. PAI with ADM can improve convergence speed with fewer ultrasonic transducers, enabling a high-performance and cost-effective PAI system for biomedical applications. Xueyan Liu, Dong Peng, Wei Guo, Xibo Ma, Xin Yang, and Jie Tian Copyright © 2012 Xueyan Liu et al. All rights reserved. Sun, 30 Dec 2012 09:33:32 +0000 http://www.hindawi.com/journals/ijbi/2012/192730/ Generalized diffusion tensor imaging (GDTI) was developed to model complex apparent diffusivity coefficient (ADC) using higher-order tensors (HOTs) and to overcome the inherent single-peak shortcoming of DTI. However, the geometry of a complex ADC profile does not correspond to the underlying structure of fibers. This tissue geometry can be inferred from the shape of the ensemble average propagator (EAP). Though interesting methods for estimating a positive ADC using 4th-order diffusion tensors were developed, GDTI in general was overtaken by other approaches, for example, the orientation distribution function (ODF), since it is considerably difficult to recuperate the EAP from a HOT model of the ADC in GDTI. In this paper, we present a novel closed-form approximation of the EAP using Hermite polynomials from a modified HOT model of the original GDTI-ADC. Since the solution is analytical, it is fast, differentiable, and the approximation converges well to the true EAP. This method also makes the effort of computing a positive ADC worthwhile, since now both the ADC and the EAP can be used and have closed forms. We demonstrate our approach with 4th-order tensors on synthetic data and in vivo human data. Aurobrata Ghosh and Rachid Deriche Copyright © 2012 Aurobrata Ghosh and Rachid Deriche. All rights reserved. Mon, 24 Dec 2012 14:52:24 +0000 http://www.hindawi.com/journals/ijbi/2012/738283/ A wide range of studies show the capacity of multivariate statistical methods for fMRI to improve mapping of brain activations in a noisy environment. An advanced method uses local canonical correlation analysis (CCA) to encompass a group of neighboring voxels instead of looking at the single voxel time course. The value of a suitable test statistic is used as a measure of activation. It is customary to assign the value to the center voxel; however, this is a choice of convenience and without constraints introduces artifacts, especially in regions of strong localized activation. To compensate for these deficiencies, different spatial constraints in CCA have been introduced to enforce dominance of the center voxel. However, even if the dominance condition for the center voxel is satisfied, constrained CCA can still lead to a smoothing artifact, often called the “bleeding artifact of CCA”, in fMRI activation patterns. In this paper a new method is introduced to measure and correct for the smoothing artifact for constrained CCA methods. It is shown that constrained CCA methods corrected for the smoothing artifact lead to more plausible activation patterns in fMRI as shown using data from a motor task and a memory task. Dietmar Cordes, Mingwu Jin, Tim Curran, and Rajesh Nandy Copyright © 2012 Dietmar Cordes et al. All rights reserved. Sat, 22 Dec 2012 12:07:12 +0000 http://www.hindawi.com/journals/ijbi/2012/765649/ During the last decade, several works have dealt with computer automatic diagnosis (CAD) of masses in digital mammograms. Generally, the main difficulty remains the detection of masses. This work proposes an efficient methodology for mass detection based on a new local feature extraction. Local binary pattern (LBP) operator and its variants proposed by Ojala are a powerful tool for textures classification. However, it has been proved that such operators are not able to model at their own texture masses. We propose in this paper a new local pattern model named gray level and local difference (GLLD) where we take into consideration absolute gray level values as well as local difference as local binary features. Artificial neural networks (ANNs), support vector machine (SVM), and k-nearest neighbors (kNNs) are, then, used for classifying masses from nonmasses, illustrating better performance of ANN classifier. We have used 1000 regions of interest (ROIs) obtained from the Digital Database for Screening Mammography (DDSM). The area under the curve of the corresponding approach has been found to be for the mass detection step. A comparative study with previous approaches proves that our approach offers the best performances. N. Gargouri, A. Dammak Masmoudi, D. Sellami Masmoudi, and R. Abid Copyright © 2012 N. Gargouri et al. All rights reserved. Thu, 20 Dec 2012 17:14:35 +0000 http://www.hindawi.com/journals/ijbi/2012/350853/ Lung radiotherapy is greatly benefitted when the tumor motion caused by breathing can be modeled. The aim of this paper is to present the importance of using anisotropic and subject-specific tissue elasticity for simulating the airflow inside the lungs. A computational-fluid-dynamics (CFD) based approach is presented to simulate airflow inside a subject-specific deformable lung for modeling lung tumor motion and the motion of the surrounding tissues during radiotherapy. A flow-structure interaction technique is employed that simultaneously models airflow and lung deformation. The lung is modeled as a poroelastic medium with subject-specific anisotropic poroelastic properties on a geometry, which was reconstructed from four-dimensional computed tomography (4DCT) scan datasets of humans with lung cancer. The results include the 3D anisotropic lung deformation for known airflow pattern inside the lungs. The effects of anisotropy are also presented on both the spatiotemporal volumetric lung displacement and the regional lung hysteresis. Olusegun J. Ilegbusi, Zhiliang Li, Behnaz Seyfi, Yugang Min, Sanford Meeks, Patrick Kupelian, and Anand P. Santhanam Copyright © 2012 Olusegun J. Ilegbusi et al. All rights reserved. Wed, 19 Dec 2012 14:44:12 +0000 http://www.hindawi.com/journals/ijbi/2012/747264/ Rationale and Objectives. Testing a quantitative, noninvasive method to assess postangioplasty vessel wall changes in an animal model. Material and Methods. Six New Zealand white rabbits were subjected to atherosclerotic injury, including cholesterol-enriched diet, deendothelialization, and percutaneous transluminal angioplasty (PTA) in the distal part of abdominal aorta (four weeks after deendothelialization). The animals were examined with a 1.5T MRI scanner at three times as follows: baseline (six weeks after diet start and two days after PTA) and four weeks and 10 weeks after-PTA. Inflow angiosequence (M2DI) and proton-density-weighted sequence (PDW) were performed to examine the aorta with axial slices. To identify the inner and outer vessel wall boundaries, a dynamic contour algorithm (Gradient Vector Flow Snakes) was applied to the images, followed by calculation of the vessel wall dimensions. The results were compared with histopathological analysis. Results. The wall thickness in the lesion was significantly higher than in the control region at 4 and 10 weeks, reflecting induction of experimentally created after-angioplasty lesion. At baseline, no significant difference between the two regions was present. Conclusions. It is possible to follow the development of vessel wall changes after-PTA with MRI in this rabbit model. Mari Hänni, Olli Leppänen, and Örjan Smedby Copyright © 2012 Mari Hänni et al. All rights reserved. Wed, 28 Nov 2012 09:15:22 +0000 http://www.hindawi.com/journals/ijbi/2012/285136/ Accurate pulmonary image registration is a challenging problem when the lungs have a deformation with large distance. In this work, we present a nonrigid volumetric registration algorithm to track lung motion between a pair of intrasubject CT images acquired at different inflation levels and introduce a new vesselness similarity cost that improves intensity-only registration. Volumetric CT datasets from six human subjects were used in this study. The performance of four intensity-only registration algorithms was compared with and without adding the vesselness similarity cost function. Matching accuracy was evaluated using landmarks, vessel tree, and fissure planes. The Jacobian determinant of the transformation was used to reveal the deformation pattern of local parenchymal tissue. The average matching error for intensity-only registration methods was on the order of 1 mm at landmarks and 1.5 mm on fissure planes. After adding the vesselness preserving cost function, the landmark and fissure positioning errors decreased approximately by 25% and 30%, respectively. The vesselness cost function effectively helped improve the registration accuracy in regions near thoracic cage and near the diaphragm for all the intensity-only registration algorithms tested and also helped produce more consistent and more reliable patterns of regional tissue deformation. Kunlin Cao, Kai Ding, Joseph M. Reinhardt, and Gary E. Christensen Copyright © 2012 Kunlin Cao et al. All rights reserved. Mon, 19 Nov 2012 14:53:49 +0000 http://www.hindawi.com/journals/ijbi/2012/676808/ In order to better predict and follow treatment responses in cancer patients, there is growing interest in noninvasively characterizing tumor heterogeneity based on MR images possessing different contrast and quantitative information. This requires mechanisms for integrating such data and reducing the data dimensionality to levels amenable to interpretation by human readers. Here we propose a two-step pipeline for integrating diffusion and perfusion MRI that we demonstrate in the quantification of breast lesion heterogeneity. First, the images acquired with the two modalities are aligned using an intermodal registration. Dissimilarity-based clustering is then performed exploiting the information coming from both modalities. To this end an ad hoc distance metric is developed and tested for tuning the weighting for the two modalities. The distributions of the diffusion parameter values in subregions identified by the algorithm are extracted and compared through nonparametric testing for posterior evaluation of the tissue heterogeneity. Results show that the joint exploitation of the information brought by DCE and DWI leads to consistent results accounting for both perfusion and microstructural information yielding a greater refinement of the segmentation than the separate processing of the two modalities, consistent with that drawn manually by a radiologist with access to the same data. C. Andrés Méndez, Francesca Pizzorni Ferrarese, Paul Summers, Giuseppe Petralia, and Gloria Menegaz Copyright © 2012 C. Andrés Méndez et al. All rights reserved. Sun, 11 Nov 2012 13:23:33 +0000 http://www.hindawi.com/journals/ijbi/2012/658101/ Ajna Borogovac and Iris Asllani Copyright © 2012 Ajna Borogovac and Iris Asllani. All rights reserved. Thu, 08 Nov 2012 09:06:47 +0000 http://www.hindawi.com/journals/ijbi/2012/734734/ Objective. To define the sensitivity of microcomputed tomography- (micro-CT-) derived descriptors for the quantification of lung damage caused by elastase instillation. Materials and Methods. The lungs of 30 elastase treated and 30 control A/J mice were analyzed 1, 6, 12, and 24 hours and 7 and 17 days after elastase instillation using (i) breath-hold-gated micro-CT, (ii) pulmonary function tests (PFTs), (iii) RT-PCR for RNA cytokine expression, and (iv) histomorphometry. For the latter, an automatic, parallel software toolset was implemented that computes the airspace enlargement descriptors: mean linear intercept and weighted means of airspace diameters (, , and ). A Support Vector Classifier was trained and tested based on three nonhistological descriptors using as ground truth. Results. detected statistically significant differences between the groups at all time points. Furthermore, at 1 hour (24 hours) was significantly lower than at 24 hours (7 days). The classifier trained on the micro-CT-derived descriptors achieves an area under the curve (AUC) of 0.95 well above the others (PFTS AUC = 0.71; cytokine AUC = 0.88). Conclusion. Micro-CT-derived descriptors are more sensitive than the other methods compared, to detect in vivo early signs of the disease. Arrate Muñoz-Barrutia, Mario Ceresa, Xabier Artaechevarria, Luis M. Montuenga, and Carlos Ortiz-de-Solorzano Copyright © 2012 Arrate Muñoz-Barrutia et al. All rights reserved. Thu, 08 Nov 2012 08:34:42 +0000 http://www.hindawi.com/journals/ijbi/2012/942326/ We investigated the potential of fluorescence molecular tomography to image ex vivo samples collected from a large animal model, in this case, a dog spine. Wide-field time-gated fluorescence tomography was employed to assess the impact of multiview acquisition, data type, and intrinsic optical properties on the localization and quantification accuracy in imaging a fluorescent inclusion in the intervertebral disk. As expected, the TG data sets, when combining early and late gates, provide significantly better performances than the CW data sets in terms of localization and quantification. Moreover, the use of multiview imaging protocols led to more accurate localization. Additionally, the incorporation of the heterogeneous nature of the tissue in the model to compute the Jacobians led to improved imaging performances. This preliminary imaging study provides a proof of concept of the feasibility of quantitatively imaging complex ex vivo samples nondestructively and with short acquisition times. This work is the first step towards employing optical molecular imaging of the spine to detect and characterize disc degeneration based on targeted fluorescent probes. Monish Pimpalkhare, Jin Chen, Vivek Venugopal, and Xavier Intes Copyright © 2012 Monish Pimpalkhare et al. All rights reserved. Thu, 18 Oct 2012 16:17:32 +0000 http://www.hindawi.com/journals/ijbi/2012/956248/ We have previously demonstrated the 24-hour redistribution and reabsorption of bronchoalveolar lavage (BAL) fluid delivered to the lung during a bronchoscopic procedure in normal volunteers. In this work we utilize image-matching procedures to correlate fluid redistribution and reabsorption to changes in regional lung function. Lung CT datasets from six human subjects were used in this study. Each subject was scanned at four time points before and after BAL procedure. Image registration was performed to align images at different time points and different inflation levels. The resulting dense displacement fields were utilized to track tissue volume changes and reveal deformation patterns of local parenchymal tissue quantitatively. The registration accuracy was assessed by measuring landmark matching errors, which were on the order of 1 mm. The results show that quantitative-assessed fluid volume agreed well with bronchoscopist-reported unretrieved BAL volume in the whole lungs (squared linear correlation coefficient was 0.81). The average difference of lung tissue volume at baseline and after 24 hours was around 2%, which indicates that BAL fluid in the lungs was almost absorbed after 24 hours. Regional lung-function changes correlated with the presence of BAL fluid, and regional function returned to baseline as the fluid was reabsorbed. Kunlin Cao, Gary E. Christensen, Kai Ding, Kaifang Du, Maghavan L. Raghavan, Ryan E. Amelon, Kimberly M. Baker, Eric A. Hoffman, and Joseph M. Reinhardt Copyright © 2012 Kunlin Cao et al. All rights reserved. Tue, 09 Oct 2012 09:38:20 +0000 http://www.hindawi.com/journals/ijbi/2012/382806/ Regional quantitative analysis of airway morphological abnormalities is of great interest in lung disease investigation. Considering that pulmonary lobes are relatively independent functional unit, we develop and test a novel and efficient computerized scheme in this study to automatically and robustly classify the airways into different categories in terms of pulmonary lobe. Given an airway tree, which could be obtained using any available airway segmentation scheme, the developed approach consists of four basic steps: (1) airway skeletonization or centerline extraction, (2) individual airway branch identification, (3) initial rule-based airway classification/labeling, and (4) self-correction of labeling errors. In order to assess the performance of this approach, we applied it to a dataset consisting of 300 chest CT examinations in a batch manner and asked an image analyst to subjectively examine the labeled results. Our preliminary experiment showed that the labeling accuracy for the right upper lobe, the right middle lobe, the right lower lobe, the left upper lobe, and the left lower lobe is 100%, 99.3%, 99.3%, 100%, and 100%, respectively. Among these, only two cases are incorrectly labeled due to the failures in airway detection. It takes around 2 minutes to label an airway tree using this algorithm. Suicheng Gu, Zhimin Wang, Jill M. Siegfried, David Wilson, William L. Bigbee, and Jiantao Pu Copyright © 2012 Suicheng Gu et al. All rights reserved. Wed, 11 Jul 2012 09:42:15 +0000 http://www.hindawi.com/journals/ijbi/2012/463408/ We propose a regularization based approach for case-adaptive classification in computer-aided diagnosis (CAD) of breast cancer. The goal is to improve the classification accuracy on a query case by making use of a set of similar cases retrieved from an existing library of known cases. In the proposed approach, a prior is first derived from a traditional CAD classifier (which is typically pre-trained offline on a set of training cases). It is then used together with the retrieved similar cases to obtain an adaptive classifier on the query case. We consider two different forms for the regularization prior: one is fixed for all query cases and the other is allowed to vary with different query cases. In the experiments the proposed approach is demonstrated on a dataset of 1,006 clinical cases. The results show that it could achieve significant improvement in numerical efficiency compared with a previously proposed case adaptive approach (by about an order of magnitude) while maintaining similar (or better) improvement in classification accuracy; it could also adapt faster in performance with a small number of retrieved cases. Measured by the area of under the ROC curve (AUC), the regularization based approach achieved AUC = 0.8215, compared with AUC = 0.7329 for the baseline classifier (𝑃-value=0.001). Hao Jing, Yongyi Yang, and Robert M. Nishikawa Copyright © 2012 Hao Jing et al. All rights reserved. Tue, 26 Jun 2012 15:24:20 +0000 http://www.hindawi.com/journals/ijbi/2012/727154/ The optic disc (OD) is an important anatomical feature in retinal images, and its detection is vital for developing automated screening programs. Currently, there is no algorithm designed to automatically detect the OD in fundus images captured from Asians which are larger and have thicker vessels compared to Caucasians. In this paper, we propose such a method to complement current algorithms using two steps: OD vessel candidate detection and OD vessel candidate matching. The first step is achieved with multiscale Gaussian filtering, scale production, and double thresholding to initially extract the vessels' directional map of various thicknesses. The map is then thinned before another threshold is applied to remove pixels with low intensities. This result forms the OD vessel candidates. In the second step, a Vessels' Directional Matched Filter (VDMF) of various dimensions is applied to the candidates to be matched, and the pixel with the smallest difference designated the OD center. We tested the proposed method on a new database consisting of 402 images from a diabetic retinopathy (DR) screening programme consisting of Asians. The OD center was successfully detected with an accuracy of 99.25% (399/402). Bob Zhang, Jane You, and Fakhri Karray Copyright © 2012 Bob Zhang et al. All rights reserved. Tue, 26 Jun 2012 09:16:25 +0000 http://www.hindawi.com/journals/ijbi/2012/509783/ The blood vessel morphology is known to correlate with several diseases, such as cancer, and is important for describing several tissue physiological processes, like angiogenesis. Therefore, a quantitative method for characterizing the angiography obtained from medical images would have several clinical applications. Optical microangiography (OMAG) is a method for obtaining three-dimensional images of blood vessels within a volume of tissue. In this study we propose to quantify OMAG images obtained with a spectral domain optical coherence tomography system. A technique for determining three measureable parameters (the fractal dimension, the vessel length fraction, and the vessel area density) is proposed and validated. Finally, the repeatability for acquiring OMAG images is determined, and a new method for analyzing small areas from these images is proposed. Roberto Reif, Jia Qin, Lin An, Zhongwei Zhi, Suzan Dziennis, and Ruikang Wang Copyright © 2012 Roberto Reif et al. All rights reserved. Wed, 06 Jun 2012 10:58:40 +0000 http://www.hindawi.com/journals/ijbi/2012/459286/ Abdominal aortic calcifications (AACs) correlate strongly with coronary artery calcifications and can be predictors of cardiovascular mortality. We investigated whether size, shape, and distribution of AACs are related to mortality and how such prognostic markers perform compared to the state-of-the-art AC24 marker introduced by Kauppila. Methods. For 308 postmenopausal women, we quantified the number of AAC and the percentage of the abdominal aorta that the lesions occupied in terms of their area, simulated plaque area, thickness, wall coverage, and length. We analysed inter-/intraobserver reproducibility and predictive ability of mortality after 8-9 years via Cox regression leading to hazard ratios (HRs). Results. The coefficient of variation was below 25% for all markers. The strongest individual predictors were the number of calcifications (HR=2.4) and the simulated area percentage (HR=2.96) of a calcified plaque, and, unlike AC24 (HR=1.66), they allowed mortality prediction also after adjusting for traditional risk factors. In a combined Cox regression model, the strongest complementary predictors were the number of calcifications (HR=2.76) and the area percentage (HR=−3.84). Conclusion. Morphometric markers of AAC quantified from radiographs may be a useful tool for screening and monitoring risk of CVD mortality. Melanie Ganz, Marleen de Bruijne, Erik B. Dam, Paola Pettersen, Morten A. Karsdal, Claus Christiansen, and Mads Nielsen Copyright © 2012 Melanie Ganz et al. All rights reserved.