Noise and intensity non-uniformity are causing major difficulties in magnetic resonance (MR) image segmentation. This paper introduces a variational level set approach for simultaneous MR image segmentation and intensity non-uniformity correction. The proposed energy functional is based on local Gaussian intensity fitting with local means and variances. Furthermore, the proposed ...

OBJECTIVES: To compare ischaemic lesions predicted by different CT perfusion (CTP) post-processing techniques and validate CTP lesions compared with final lesion size in stroke patients. METHODS: Fifty patients underwent CT, CTP and CT angiography. Quantitative values and colour maps were calculated using least mean square deconvolution (LMSD), maximum slope (MS) ...

Background and purpose. In radiotherapy (RT), target soft tissues are best defined on MR images. In several cases, CT imaging is needed only for dose calculation and generation of digitally reconstructed radiographs (DRRs). Image co-registration errors between MRI and CT can be avoided by using MRI-only based treatment planning, especially ...

Aim: Most of the research efforts in magnetic targeting have been focused on the development of magnetic nanovectors, while the investigation of methods for tracking their magnetic targeting efficiency remains inappropriately addressed. We propose herein a miniaturized approach for appraising magnetophoretic mobility at the nanoscale. Materials & methods: A simple ...

Abstract Objective: The aim of this study is to emphasize on the diagnostic effectiveness of fetal MRI that led to increased utilization in fetal medicine as well as its value in prognosis and decision making in the modern obstetric practice. Methods: One hundred five (n= 105) pregnant women were referred ...

Abstract Introduction: Computed tomography (CT) has been approved for diagnosing chronic obstructive pulmonary disease (COPD). The diagnostic accuracy, however, has never been examined in a systematic review. Therefore, we conducted a meta-analysis to evaluate the accuracy of CT in diagnosing COPD. Methods: Articles reporting diagnostic accuracy of CT for COPD ...

INTRODUCTION: The insertion of thoracic pedicle screws (T1-T10) is subject to a relevant rate of malplacement. The optimum implantation procedure is still a topic of controversial debate. Currently, a postoperative computed tomography is required to evaluate the screw positions. The present study was undertaken to clarify whether intraoperative 3D imaging ...

ABSTRACT: BACKGROUND: Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to ...

Image-guided alignment procedures in radiotherapy aim at minimizing discrepancies between the planned and the real patient setup. For that purpose, we developed a 2D/3D approach which rigidly registers a computed tomography (CT) with two x-rays by maximizing the agreement in pixel intensity between the x-rays and the corresponding reconstructed radiographs ...

Cross-sectional study using T1ρ magnetic resonance imaging (MRI) of lumbar spine in healthy young adults. To evaluate early intervertebral disc degeneration (IDD) quantified by T1ρ- and T2-weighted MRI in asymptomatic young adults and to correlate T1ρ value with Pfirrmann degenerative grade, sex, and body mass index (BMI). Intervertebral disc starts ...

In radiotherapy, cone-beam computerized tomography (CBCT) scans are used for position correction for various tumour sites. At the start of the treatment, a CT scan that serves as input for a treatment planning is acquired. A CBCT scan is made prior to the irradiation of the tumour. Because there might ...

Coronary computed tomography angiography (CTA) plays an important role in the identification of coronary artery disease in low- to intermediate-risk patients. Even with a "restrictive" field of view, coronary CTA data sets will include visualization of structures adjacent to the heart, including the thoracic great vessels, pericardium, mediastinum, lungs, and ...

BACKGROUND: Many factors can jeopardize the accuracy of deep brain stimulation (DBS) lead placement. Confirmation of lead placement while the patient is still in the operating room would be advantageous. Intraoperative MRI or CT can identify placement errors, but these modalities can be cost- or time prohibitive. Intraoperative fluoroscopy may ...

One of the challenges in the development of photon counting spectral CT detectors is that the location of the energy thresholds tends to vary among detector elements. If not compensated for, this threshold variation leads to ring artifacts in the reconstructed images. In the present article, a framework is presented ...

This Special Report presents the consensus of the Summit on Management of Radiation Dose in Computed Tomography (CT) (held in February 2011), which brought together participants from academia, clinical practice, industry, and regulatory and funding agencies to identify the steps required to reduce the effective dose from routine CT examinations ...

Fano resonances in plasmonic nanostructures are important for plasmon line shaping. Compared to a single Fano resonance, multiple Fano resonances can modify plasmon lines at several spectral positions simultaneously, but they often suffer from weak modulation depths. In this paper, plasmonic heptamer clusters comprised of split nanorings are designed to ...

A series of rare complicated duodenal diverticula were reported with emphasis on causes for misdiagnosis. Patients with a discharge diagnosis of complicated duodenal diverticulum were retrospectively obtained. Computed tomographic (CT) reports and findings were reviewed. Complications consisted of diverticulitis (n=2), perforation (n=7), or obstructive cholangitis (n=2). CT imaging demonstrated a ...

Magnetic resonance imaging (MRI) is a common clinical tool used to diagnose and monitor the progression and/or healing of osteochondritis dissecans of the knee. The purpose of this study was to systematically review the literature relative to the following questions: (1) Is MRI a valid, sensitive, specific, accurate, and reliable ...

The effects of body mass and temperature on metabolic rate (MR) are among the most widely examined physiological relationships. Recently, these relationships have been incorporated into the metabolic theory of ecology (MTE) that links the ecology of populations, communities and ecosystems to the MR of individual organisms. The fundamental equation ...

To develop and validate an informatics toolkit that extracts anatomy-specific computed tomography (CT) radiation exposure metrics (volume CT dose index and dose-length product) from existing digital image archives through optical character recognition of CT dose report screen captures (dose screens) combined with Digital Imaging and Communications in Medicine attributes. This ...

BACKGROUND: Tissue expansion for breast reconstruction after mastectomy is a safe and effective procedure. A magnetic resonance imaging (MRI) scan can be requested for patients with a breast expander to evaluate concurrent diseases. The electromagnetic field of the MR can interfere with biomedical devices, resulting in potential hazards, compromising the ...

Recent studies have demonstrated that ultra-high resolution MRA imaging using 7 Tessla (T) MRI can be employed to noninvasively visualize the lenticulostriate arteries (LSA) that supply the basal ganglia and internal capsule. Subcortical vascular dementia (SVaD) is believed to involve these regions from an early stage. We investigated whether LSA ...

To determine whether 3D cone-beam computed tomography (CBCT) guidance allows safe and accurate biopsy of suspected small renal masses (SRM), especially in hard-to-reach anatomical locations. CBCT guidance was used to perform 41 stereotactic biopsy procedures of lesions that were inaccessible for ultrasound guidance or CT guidance. In CBCT guidance, a ...

Purpose: To compare demons deformable registration with rigid and affineregistration methods by measuring registration accuracy and image texture changes introduced by each algorithm. Methods: Eleven temporally sequential pairs of clinical thoracic CT scans demonstrating no abnormal pathology were collected retrospectively from different patients. Rigid, affine, and demons registration methods were ...

Tracking of triangular or sawtooth waveforms is a major difficulty for achieving high-speed operation in many scanning applications such as scanning probe microscopy. Such non-smooth waveforms contain high order harmonics of the scan frequency that can excite mechanical resonant modes of the positioning system, limiting the scan range and bandwidth. ...

Purpose: With the development of RT treatment planning systems that use the relationship between CT number and Electron Density (ED), rather than the Linear Attenuation Coefficient (LAC) of a given material, a number of authors have pointed out the divergence between the linearity of CT numbers vs. LAC in the ...

To validate a novel approach for accelerated four-dimensional phase contrast MR imaging (4D PC-MRI) with an extended range of velocity sensitivity. 4D PC-MRI data were acquired with a radially undersampled trajectory (PC-VIPR). A dual V(enc) (dV(enc) ) processing algorithm was implemented to investigate the potential for scan time savings while ...

Purpose: To design a novel phantom compatible with multiple imaging modalities (kV, MV and MRI) for the daily quality assurance (QA) of an MR-guided linac. Methods: At our institution, we are in the process of installing a decoupled MR-linac system, consisting of a 1.5T Siemens Espree MR scanner on rails ...

Purpose: Quantitative analysis in CT imaging often requires image data set of lesions with ground truth, which is practically impossible in general. This study presents a simple CT simulation model which enables to create realistic synthetic CT images of numerical voxel phantoms for small lesionswith various shape and sizes. Methods: ...

Conventional X-ray microcomputed tomography (micro-CT) is not usually sufficient to determine microscopic compositional distributions as it is limited to measuring the X-ray attenuation of the sample, which for a given dataset can be similar for materials of different composition. In contrast, the present work enables three-dimensional compositional analysis with a ...

Purpose: A sensitivity analysis of the effect of variations in electron density data (ED) on dose calculation accuracy for MRI based cervical cancer treatment planning. Methods: Five cervical cancer patients were analysed in this work. Planning CT scans represented gold standard ED data. Standard four field 3DCRT plans (prescription 45Gy) ...

Purpose: To enhance the quality of proton/carbon radiography for real time tumor tracking using CT prior knowledge. Methods: A method for contrast enhancement was applied to particle radiographies (230 MeV proton, 330 MeV proton, 500MeV/n Carbon) virtually generated by means of Monte Carlo simulations. CT data volumes from 6 lung ...

Purpose: In this abstract, we discuss a biomechanical head and neck model that will be able to represent patient setup variations as well as physiologic changes and subsequently enable dose calculations on the deformed anatomy. Methods: We selected Multi Pose MRI as the imaging modality to aid in model development ...

Purpose: To develop a Graphics Processing Unit (GPU) based Monte Carlo (MC) code that uses a dual-GPU system to accelerate radiographic simulation and CT imaging dose calculations. Methods: We considered two clinical cases, a chest x-ray radiography and an abdominal CT scan. In the first case, a voxelized VIP-Man phantom ...

Purpose: The aiming is to improve the mutual information based registration method for PET-CT scanner, which faces the challenges of high computational complexity and high likelihood of being trapped into local optima due to an absence of spatial information. Methods: In this work, new multi-scale registration framework called EPMR was ...

Purpose: (131)I radionuclide therapy is widely performed in a thyroid cancer treatment, but there has been almost no evaluation of the dose distribution. The aim of this work is to develop the calculation system using the data of SPECT-CT and to examine the effects of their image resolutions on the ...

Purpose: The prototype inline MRI-linac system has some advantages over perpendicular models including avoiding the electron return effect. One of the disadvantages of the inline approach is the increased skin dose, estimated to be 400-1000% of the dmax dose. The purpose of this work was to design a feasible method ...

Purpose: Monte Carlo (MC) simulation is an established technique for dose calculation in diagnostic radiology. The major drawback is its high computational demand, which limits the possibility of usage in real-time applications. The aim of this study was to develop fast on-site computed tomography (CT) specific MC dose calculations by ...

Purpose: Robust registration of prone and supine colonie surfaces acquired during CT colonography may lead to faster and more accurate detection of colorectal cancer and polyps. Any directional bias when registering one surface to the other could precipitate incorrect anatomical correspondence and engender reader error. Despite this, non-rigid registration methods ...

Purpose: Low dose CT simulation is promising technique which can be applied to dose optimization of the clinical CT images without repeating CT examinations for patients to obtain images at different dose levels. We present a virtual sinogram approach which enables low-dose CT simulation study using only conventional CT image ...

Purpose: Modern treatment planning systems require lookup tables to convert Hounsfield Units (HU) to relative electron density (RED) for use in heterogeneity corrections during dose calculations. The purpose of this work is to illustrate the impact of using different model CT phantoms to determine HU to RED curves for treatment ...

Purpose: To examine the effects of object size on scatter-corrected CT histograms to be used in threshold-based tissue segmentation. Methods: A polyethylene cone filled with various concentrations of water and methanol mixtures, simulating glandular and adipose tissues, were imaged with our quasi-monochromatic dedicated breast CT, and scatter corrected using beam-stop ...

Purpose: In an earlier work, we demonstrated that substitutes for CT images can be derived from MR images using ultrashort echo time (UTE) sequences, conventional T2 weighted sequences, and Gaussian mixture regression (GMR). In this study, we extend this work by analyzing the uncertainties associated with the GMR model and ...

Purpose: To design a novel 3D automatic registration algorithm for cardiac PET/CT registration using gradient information and to evaluate the performance of the algorithm with clinical PET/CT datasets. Methods: The 512×512×47 CT images are at first resized to 128×128×47 to match the matrix size of PET. In order to maximize ...

Purpose: To characterize the targeting accuracy of a small animal irradiator, (XRad225Cx, Precision X-Ray Inc.), producing 225kVp circular or square fields ranging from 1mm-40mm dimensions. Targeting accuracy is critical for accurate interpretation of pre-clinical dose-volume response, but is extremely challenging, due to the extremely small field sizes. Characterization was performed ...

Purpose: This study will review two alternate pathways for CT accreditation - the program of the American College of Radiology (ACR) and the program of Intersocietal Accreditation Commission (IAC). The study will compare and contrast the two programs. Methods: The requirements of the ACR-CT accreditation and IAC -ICACTL programs are ...

Purpose: Two of the main challenges associated with electromagnetic (EM) tracking in computer-assisted interventions (CAIs) are (1) the compensation of systematic distance errors arising from the influence of metal near the field generator (FG) or the tracked sensor and (2) the optimized setup of the FG to maximize tracking accuracy ...

Purpose: To investigate the feasibility of accurate quantification of concentrations of mixtures of K-edge contrast agents in spectral Computed Tomography (CT) imaging based on a novel maximum likelihood based method. Methods: Calcium, gold, and iodine solutions of various concentrations were prepared in vials and placed in phantoms for imaging at ...

Purpose: A study was undertaken to investigate the response of the ArcCHECK phantom distributed by Sun Nuclear (SNC) to different treatment modalities including Static, IMRT, Arc and VMAT and to understand patient-specific QA results. Methods: An ArcCHECK kV-CT data image was acquired and two digital image sets assigned a uniform ...

Purpose: In X-ray computed tomography (CT), X-rays are significantly less attenuated in the anteroposterior direction and more in the lateral direction. Therefore, the tube current should be adjusted within one gantry rotation using angular tube current modulation (TCM). The aim of this study was to evaluate whether online angular TCM ...