Brain activation difference evoked by different binocular disparities of stereograms: An fMRI study.

The binocular disparity of two retina images is a main cue of stereoscopic vision. However, the global dependency between brain response and binocular disparity still remains unclear. Here, we used functional Magnetic Resonance Imaging (fMRI) to identify stereopsis-related brain regions with a modified Random Dot Stereogram (RDS) and plotted the activation variation curves under different disparity size.

Concomitant Imaging Dose and Cancer Risk in Image Guided Thoracic Radiation Therapy.

Purpose: Kilovoltage cone beam computed tomography (CT) (kVCBCT) imaging guidance improves the accuracy of radiation therapy but imposes an extra radiation dose to cancer patients. This study aimed to investigate concomitant imaging dose and associated cancer risk in image guided thoracic radiation therapy.

Methods And Materials: The planning CT images and structure sets of 72 patients were converted to CT phantoms whose chest circumferences (Cchest) were calculated retrospectively.

Free-Breathing 3D Imaging of Right Ventricular Structure and Function Using Respiratory and Cardiac Self-Gated Cine MRI.

Providing a movie of the beating heart in a single prescribed plane, cine MRI has been widely used in clinical cardiac diagnosis, especially in the left ventricle (LV). Right ventricular (RV) morphology and function are also important for the diagnosis of cardiopulmonary diseases and serve as predictors for the long term outcome. The purpose of this study is to develop a self-gated free-breathing 3D imaging method for RV quantification and to evaluate its performance by comparing it with breath-hold 2D cine imaging in 7 healthy volunteers.

Functional and anatomical properties of human visual cortical fields.

Human visual cortical fields (VCFs) vary in size and anatomical location across individual subjects. Here, we used functional magnetic resonance imaging (fMRI) with retinotopic stimulation to identify VCFs on the cortical surface. We found that aligning and averaging VCF activations across the two hemispheres provided clear delineation of multiple retinotopic fields in visual cortex.

Distributed CT image reconstruction algorithm based on the alternating direction method.

With the development of compressive sensing theory, image reconstruction from few-view projections has been paid considerable research attention in the field of computed tomography (CT). Total variation (TV)-based CT image reconstruction has been shown experimentally to be capable of producing accurate reconstructions from sparse-view data. Motivated by the need of solving few-view reconstruction problem with large scale data, a general block distribution reconstruction algorithm based on TV minimization and the alternating direction method (ADM) has been developed in this study.

Interior reconstruction method based on rotation-translation scanning model.

In various applications of computed tomography (CT), it is common that the reconstructed object is over the field of view (FOV) or we may intend to sue a FOV which only covers the region of interest (ROI) for the sake of reducing radiation dose. These kinds of imaging situations often lead to interior reconstruction problems which are difficult cases in the reconstruction field of CT, due to the truncated projection data at every view angle. In this paper, an interior reconstruction method is developed based on a rotation-translation (RT) scanning model.

Ultrashort echo time bi-component analysis of cortical bone--a field dependence study.

Purpose: The purpose of this study is to investigate the effect of differing field strength on the T2* of cortical bone at 1.5 T and 3 T.

Methods: Ultrashort echo time pulse sequences were used to study six bovine and nine human bone samples at 1.

Personalized estimation of dose to red bone marrow and the associated leukaemia risk attributable to pelvic kilo-voltage cone beam computed tomography scans in image-guided radiotherapy.

The aim of this study is to investigate the imaging dose to red bone marrow (RBM) and the associated leukaemia risks attributable to pelvic kilo-voltage cone beam computed tomography (kVCBCT) scans in image-guided radiation therapy (IGRT). The RBM doses of 42 patients (age 2.7-86.

Fast reconstruction of flat region in a super-short scan based on MD-FBP algorithm.

In circular cone-beam computed tomography (CT), although the minimum data filtered-backprojection (MD-FBP) algorithm has many significant applications, such as handling super-short scan problem, its reconstruction efficiency is limited by the heavy calculation of backprojection. In this paper, aiming at the image reconstruction of flat region in a super-short scan, an improved method based on MD-FBP algorithm is developed using an integral operation with fixed integral interval during the implementation of backprojection, which has an improvement in reconstruction efficiency and parallel performance compared with the original MD-FBP algorithm. It is found that if the thickness of the flat region is less than 0.

Personalized assessment of kV cone beam computed tomography doses in image-guided radiotherapy of pediatric cancer patients.

Purpose: To develop a quantitative method for the estimation of kV cone beam computed tomography (kVCBCT) doses in pediatric patients undergoing image-guided radiotherapy.

Methods And Materials: Forty-two children were retrospectively analyzed in subgroups of different scanned regions: one group in the head-and-neck and the other group in the pelvis. Critical structures in planning CT images were delineated on an Eclipse treatment planning system before being converted into CT phantoms for Monte Carlo simulations.

Synthesis, radiolabeling, biodistribution and fluorescent imaging of histidine-coupled hematoporphyrin.

Introduction: Hematoporphyrin (Hp) and hematoporphyrin derivatives (HpDs) have been widely used as photosensitizers in photodynamic therapy (PDT). Radiolabeling of HpDs is helpful for preclinical and clinical studies of PDT.

Methods: The histidine-coupled hematoporphyrin (His-Hp) was synthesized and radiolabeled with [(99m)Tc(CO)(3)(H(2)O)(3)](+).

Investigation of motion artifacts associated with fat saturation technique in 3D flash imaging.

Purpose: Fast low-angle shot (FLASH) imaging is widely used in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) because it permits fast and accurate T1 measurement in vivo. Suppression of the fat signal is necessary for most FLASH applications; otherwise, fat will appear hyperintense. The fat saturation technique is one popular method to reduce fat images on clinical scanners.

Feasibility of high temporal resolution breast DCE-MRI using compressed sensing theory.

Purpose: To investigate the feasibility of high temporal resolution breast DCE-MRI using compressed sensing theory.

Methods: Two experiments were designed to investigate the feasibility of using reference image based compressed sensing (RICS) technique in DCE-MRI of the breast. The first experiment examined the capability of RICS to faithfully reconstruct uptake curves using undersampled data sets extracted from fully sampled clinical breast DCE-MRI data.

Flow compensation for the fast spin echo triple-echo Dixon sequence.

The fast spin echo (FSE) triple-echo Dixon (FTED) sequence uses bipolar triple-echo readout during each echo-spacing period of FSE to collect all the images necessary for Dixon water and fat separation in a single scan. In comparison to other FSE implementations of the Dixon technique, the triple echo readout used in FTED incurs minimal deadtime in the pulse sequence design and thus greatly enhances the overall scan efficiency. A potential drawback of FTED is that the time dependence of the gradient moment along the frequency encode direction becomes more complicated than in FSE and flow compensation based on the gradient moment (GM) nulling is difficult to achieve.

Quantitative analysis of clinical dynamic contrast-enhanced MR imaging for evaluating treatment response in human breast cancer.

Purpose: To develop a method that combines a fixed-T1, fuzzy c-means (FCM) technique with a reference region (RR) model (T1-FCM method) to estimate pharmacokinetic parameters without measuring the arterial input function or baseline T1, or T1(0), and to demonstrate its feasibility in the assessment of treatment response to neoadjuvant chemotherapy (NAC) in patients with breast cancer by using data from dynamic contrast material-enhanced magnetic resonance (MR) imaging.

Materials And Methods: This study was approved by the human investigation committees of the two participating institutions. All patients gave written informed consent.

Fast finite Hilbert transform via DE quadrature scheme.

Purpose: The finite Hilbert transform (FHT) or inverse finite Hilbert transform (IFHT) is recently found to have some important applications in computerized tomography (CT) arena, where they are used to filter the derivatives of back-projected data in the chord-line based CT reconstruction algorithms. In this paper, we implemented, improved and validated a fast numerical solution to the FHT via a double exponential (DE) integration scheme. A same strategy can be used to compute IFHT.

A clinically feasible method to estimate pharmacokinetic parameters in breast cancer.

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is the MRI technique of choice for detecting breast cancer, which can be roughly classified as either quantitative or semiquantitative. The major advantage of quantitative DCE-MRI is its ability to provide pharmacokinetic parameters such as volume transfer constant (Ktrans) and extravascular extracellular volume fraction (ve). However, semiquantitative DCE-MRI is still the clinical MRI technique of choice for breast cancer diagnosis due to several major practical difficulties in the implementation of quantitative DCE-MRI in a clinical setting, including (1) long acquisition necessary to acquire 3D T1(0) map, (2) challenges in obtaining accurate artery input function (AIF), (3) long computation time required by conventional nonlinear least square (NLS) fitting, and (4) many illogical values often generated by conventional NLS method.

Reliable two-dimensional phase unwrapping method using region growing and local linear estimation.

In MRI, phase maps can provide useful information about parameters such as field inhomogeneity, velocity of blood flow, and the chemical shift between water and fat. As phase is defined in the (-pi,pi] range, however, phase wraps often occur, which complicates image analysis and interpretation. This work presents a two-dimensional phase unwrapping algorithm that uses quality-guided region growing and local linear estimation.

[Effects of diffusion time and diffusion gradient magnetic field on the apparent diffusion coefficient of water molecules].

Diffusion time and diffusion gradient magnetic strength are two important parameters of the pulsed gradient spin echo (PGSE) that is the most commonly used method in diffusion-weighted magnetic resonance imaging. However, the effects of the diffusion time on the apparent diffusion coefficient (ADC) in previous studies are controversial, and the effects of the diffusion gradient magnetic strength have received little attention. In this study, a new experimental protocol was designed to evaluate the effects of the two parameters on ADC.

[The physical problems in medicine].

According to the World Health Organization (WHO), the basic sciences to support the human health are chemistry, physics and informatics. Chemistry is the base of pharmacy. Physics is the base of medical instruments and equipments (MIE).

Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy.

The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction 10B(n,alpha)7Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned.

[An endorectal RF coil for MRI of the prostate].

In order to increase the SNR of the prostate image, we have designed a RF endorectal coil. Its properties have been evaluated using a network analyzer. Moreover the images got with a special phantom show that the coil has much higher SNR at the region of interest (ROI).