Medical Biophysics Commons^™

Improved Techniques For Acquisition And Analysis Of Dynamic Contrast-Enhanced Magnetic Resonance Imaging For Detecting Vascular Permeability In The Central Nervous System, Cheukkai Hui

Dissertations and Theses (Open Access)

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive technique for quantitative assessment of the integrity of blood-brain barrier and blood-spinal cord barrier (BSCB) in the presence of central nervous system pathologies. However, the results of DCE-MRI show substantial variability. The high variability can be caused by a number of factors including inaccurate T1 estimation, insufficient temporal resolution and poor contrast-to-noise ratio. My thesis work is to develop improved methods to reduce the variability of DCE-MRI results. To obtain fast and accurate T1 map, the Look-Locker acquisition technique was implemented with a novel and truly centric k-space segmentation scheme. In …

Quantitative Pulmonary Imaging Using Computed Tomography And Magnetic Resonance Imaging, George R Washko, Grace Parraga, Harvey O Coxson

Medical Biophysics Publications

Measurements of lung function, including spirometry and body plethesmography, are easy to perform and are the current clinical standard for assessing disease severity. However, these lung functional techniques do not adequately explain the observed variability in clinical manifestations of disease and offer little insight into the relationship of lung structure and function. Lung imaging and the image-based assessment of lung disease has matured to the extent that it is common for clinical, epidemiologic and genetic investigation to have a component dedicated to image analysis. There are several exciting imaging modalities currently being used for the non-invasive study of lung anatomy …

Evaluating Bronchodilator Effects In Chronic Obstructive Pulmonary Disease Using Diffusion-Weighted Hyperpolarized Helium-3 Magnetic Resonance Imaging, Miranda Kirby, Mohammadreza Heydarian, Andrew Wheatley, David G Mccormack, Grace Parraga

Medical Biophysics Publications

The objective of this study was to evaluate the regional effects of bronchodilator administration in chronic obstructive pulmonary disease (COPD) using hyperpolarized helium-3 ((3)He) MRI apparent diffusion coefficient (ADC). Ten COPD ex-smokers provided written, informed consent and underwent diffusion-weighted, hyperpolarized (3)He MRI, spirometry, and plethysmography before and 25 ± 2 min after bronchodilator administration. Pre- and postsalbutamol whole-lung (WL) ADC maps were generated and registered together to identify the lung regions containing the (3)He signal at both time points, and mean ADC within those regions of interest (ROI) was determined for a measurement of previously ventilated ROI ADC (ADC(P)). Lung …

Medical Physics Staffing For Radiation Oncology: A Decade Of Experience In Ontario, Canada., Jerry J. Battista Dr., Brenda G Clark, Michael S Patterson, Luc Beaulieu, Michael B Sharpe, L John Schreiner, Miller S Macpherson, Jacob Van Dyk

Oncology Publications

The January 2010 articles in The New York Times generated intense focus on patient safety in radiation treatment, with physics staffing identified frequently as a critical factor for consistent quality assurance. The purpose of this work is to review our experience with medical physics staffing, and to propose a transparent and flexible staffing algorithm for general use. Guided by documented times required per routine procedure, we have developed a robust algorithm to estimate physics staffing needs according to center-specific workload for medical physicists and associated support staff, in a manner we believe is adaptable to an evolving radiotherapy practice. We …

Hyperpolarized 3he Functional Magnetic Resonance Imaging Of Bronchoscopic Airway Bypass In Chronic Obstructive Pulmonary Disease., Lindsay Mathew, Miranda Kirby, Donald Farquhar, Christopher Licskai, Giles Santyr, Roya Etemad-Rezai, Grace Parraga, David G Mccormack

Medical Biophysics Publications

A 73-year-old exsmoker with Global initiative for chronic Obstructive Lung Disease stage III chronic obstructive pulmonary disease underwent airway bypass (AB) as part of the Exhale Airway Stents for Emphysema (EASE) trial, and was the only EASE subject to undergo hyperpolarized 3He magnetic resonance imaging for evaluation of lung function pre- and post-AB. 3He magnetic resonance imaging was acquired twice previously (32 and eight months pre-AB) and twice post-AB (six and 12 months post-AB). Six months post-AB, his increase in forced vital capacity was

Modeling Stochastic And Spatial Heterogeneity In A Human Airway Tree To Determine Variation In Respiratory System Resistance, Del Leary, Swati A Bhatawadekar, Grace Parraga, Geoffrey N Maksym

Medical Biophysics Publications

Asthma is a variable disease with changes in symptoms and airway function over many time scales. Airway resistance (Raw) is variable and thought to reflect changes in airway smooth muscle activity, but just how variation throughout the airway tree and the influence of gas distribution abnormalities affect Raw is unclear. We used a multibranch airway lung model to evaluate variation in airway diameter size, the role of coherent regional variation, and the role of gas distribution abnormalities on mean Raw (Raw) and variation in Raw as described by the SD (SDRaw). We modified an anatomically correct airway tree, provided by …

Chest Mri In Children: Why Bother?, Amir M Owrangi, Grace Parraga

Medical Biophysics Publications

In this issue of Respirology, Montella and colleagues ask this question: How does high‐field chest MRI compare with CT of children with non‐cystic fibrosis (CF) lung disease? In an important extension of the first description of this study where they compared MRI and CT with pulmonary function measurements, the authors evaluated how widely‐used chest CT and almost never‐utilized lung MRI compare for diagnostic imaging of chronic lung disease. Here they show that high‐field (3Tesla as compared with the 1.5Tesla clinical standard) thoracic MRI has high reliability and good‐to‐excellent agreement with CT, definitively answering the important question at hand; their results …

Optimal Strategy For Prophylactic Cranial Irradiation In Limited Stage Small Cell Lung Cancer, Edward Yu, Patricia Tai, Avi Assouline, Kurian Joseph

Data and Test Instruments

No abstract provided.

Glucose Decouples Intracellular Ca2+ Activity From Glucagon Secretion In Mouse Pancreatic Islet Alpha-Cells., Sylvain J Le Marchand, David W Piston

Farber Institute for Neuroscience Faculty Papers

The mechanisms of glucagon secretion and its suppression by glucose are presently unknown. This study investigates the relationship between intracellular calcium levels ([Ca(2+)](i)) and hormone secretion under low and high glucose conditions. We examined the effects of modulating ion channel activities on [Ca(2+)](i) and hormone secretion from ex vivo mouse pancreatic islets. Glucagon-secreting α-cells were unambiguously identified by cell specific expression of fluorescent proteins. We found that activation of L-type voltage-gated calcium channels is critical for α-cell calcium oscillations and glucagon secretion at low glucose levels. Calcium channel activation depends on K(ATP) channel activity but not on tetrodotoxin-sensitive Na(+) channels. …

Development And Implementation Of Acoustic Feedback Control For Scanning Probe Microscopy, Rodolfo Fernandez Rodriguez

Dissertations and Theses

A remote-sensing acoustic method for implementing position control feedback in Scanning Probe Microscopy (SPM) is presented. The capabilities of this feedback control using the new Whispering Gallery Acoustic Sensing (WGAS) method is demonstrated in a Shear-force Scanning Probe Microscope that uses a sharp probe attached to a piezoelectric Quartz Tuning Fork (QTF) firmly mounted on the microscope's frame. As the QTF is electrically driven its mechanical response reaches the SPM frame which then acts as a resonant cavity producing acoustic modes measured with an acoustic sensor strategically placed on the SPM head. The novelty of the WGAS resides in using …

Designing New Drugs To Treat Cardiac Arrhythmia, Yanping Ye

Dissertations and Theses

Heart failure resulting from different forms of cardiomyopathy is defined as the inability of the heart to pump sufficient blood to meet the body's metabolic demands. It is a major disease burden worldwide and the statistics show that 50% of the people who have the heart failure will eventually die from sudden cardiac death (SCD) associated with an arrhythmia. The central cause of disability and SCD is because of ventricular arrhythmias. Genetic mutations and acquired modifications to RyR2, the calcium release channel from sarcoplasmic reticulum, can increase the pathologic SR Ca2+ leak during diastole, which leads to defects in SR …

A Diffusion Tensor Imaging Software Comparison And Between Control Subjects And Subjects With Known Anatomical Diagnosis, Michael C. Moore

UNLV Theses, Dissertations, Professional Papers, and Capstones

Diffusion weighted imaging (DWI) is a magnetic resonance imaging (MRI) method that produces in vivo images of biological tissues weighted with the local micro-structural characteristics of water diffusion. Diffusion tensor imaging (DTI), a form of DWI, is useful when a tissue, such as the neural axons of white matter in the brain, has an internal fibrous structure that allows water to diffuse more rapidly in alignment with the fibers. Changes in the water diffusion pattern indicate changes in the fiber structure which can result from damage to the fibers. Measurements of the water diffusion patterns include overall diffusivity, Apparent Diffusion …

Chronic Obstructive Pulmonary Disease: Quantification Of Bronchodilator Effects By Using Hyperpolarized ³He Mr Imaging, Miranda Kirby, Lindsay Mathew, Mohammadreza Heydarian, Roya Etemad-Rezai, David G Mccormack, Grace Parraga

Medical Biophysics Publications

PURPOSE: To evaluate short-acting bronchodilator effects in chronic obstructive pulmonary disease (COPD) by using hyperpolarized helium 3 (³He) magnetic resonance (MR) imaging, spirometry, and plethysmography.

MATERIALS AND METHODS: Fourteen ex-smokers with COPD provided written informed consent to a local ethics board-approved and Health Insurance and Portability Accountability Act-compliant protocol and underwent hyperpolarized ³He and hydrogen 1 MR imaging, spirometry, and plethysmography before and a mean of 25 minutes ± 2 (standard deviation) after administration of 400 μg salbutamol. Distribution of ³He gas was evaluated by using semiautomated segmentation of ³He voxel intensities, where cluster 1 represented regions of signal void …

Three-Dimensional Ultrasound Scanning, Aaron Fenster, Grace Parraga, Jeff Bax

Medical Biophysics Publications

The past two decades have witnessed developments of new imaging techniques that provide three-dimensional images about the interior of the human body in a manner never before available. Ultrasound (US) imaging is an important cost-effective technique used routinely in the management of a number of diseases. However, two-dimensional viewing of three-dimensional anatomy, using conventional two-dimensional US, limits our ability to quantify and visualize the anatomy and guide therapy, because multiple two-dimensional images must be integrated mentally. This practice is inefficient, and may lead to variability and incorrect diagnoses. Investigators and companies have addressed these limitations by developing three-dimensional US techniques. …

Utilizing Induced Voxel Correlation In Fmri Analysis, Daniel B. Rowe, Andrew S. Nencka

Mathematics, Statistics and Computer Science Faculty Research and Publications

No abstract provided.

In-Vivo Ct Dosimetry During Virtual Colonoscopy, Jonathon W. Mueller

Dissertations and Theses (Open Access)

Virtual colonoscopy (VC) is a minimally invasive means for identifying colorectal polyps and colorectal lesions by insufflating a patient’s bowel, applying contrast agent via rectal catheter, and performing multi-detector computed tomography (MDCT) scans. The technique is recommended for colonic health screening by the American Cancer Society but not funded by the Centers for Medicare and Medicaid Services (CMS) partially because of potential risks from radiation exposure. To date, no in‐vivo organ dose measurements have been performed for MDCT scans; thus, the accuracy of any current dose estimates is currently unknown.

In this study, two TLDs were affixed to the inner …

Use Of Imaging Biomarkers To Assess Perfusion And Glucose Metabolism In The Skeletal Muscle Of Dystrophic Mice, Nabeel Ahmad, Ian Welch, Robert Grange, Jennifer Hadway, Savita Dhanvantari, David Hill, Ting-Yim Lee, Lisa M Hoffman

Robarts Imaging Publications

BACKGROUND: Duchenne muscular dystrophy (DMD) is a severe neuromuscular disease that affects 1 in 3500 boys. The disease is characterized by progressive muscle degeneration that results from mutations in or loss of the cytoskeletal protein, dystrophin, from the glycoprotein membrane complex, thus increasing the susceptibility of contractile muscle to injury. To date, disease progression is typically assessed using invasive techniques such as muscle biopsies, and while there are recent reports of the use of magnetic resonance, ultrasound and optical imaging technologies to address the issue of disease progression and monitoring therapeutic intervention in dystrophic mice, our study aims to validate …

Risk Of Second Malignant Neoplasms Following Proton Arc Therapy And Volumetric Modulated Arc Therapy For Prostate Cancer, Laura A. Rechner

Dissertations and Theses (Open Access)

The risk of second malignant neoplasms (SMNs) following prostate radiotherapy is a concern due to the large population of survivors and decreasing age at diagnosis. It is known that parallel-opposed beam proton therapy carries a lower risk than photon IMRT. However, a comparison of SMN risk following proton and photon arc therapies has not previously been reported. The purpose of this study was to predict the ratio of excess relative risk (RRR) of SMN incidence following proton arc therapy to that after volumetric modulated arc therapy (VMAT). Additionally, we investigated the impact of margin size and the effect …

Imaging Of Lung Function Using Hyperpolarized Helium-3 Magnetic Resonance Imaging: Review Of Current And Emerging Translational Methods And Applications, Sean Fain, Mark L Schiebler, David G Mccormack, Grace Parraga

Medical Biophysics Publications

During the past several years there has been extensive development and application of hyperpolarized helium-3 (HP (3)He) magnetic resonance imaging (MRI) in clinical respiratory indications such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, radiation-induced lung injury, and transplantation. This review focuses on the state-of-the-art of HP (3)He MRI and its application to clinical pulmonary research. This is not an overview of the physics of the method, as this topic has been covered previously. We focus here on the potential of this imaging method and its challenges in demonstrating new types of information that has the potential to influence clinical …

New To Ols For Monitoring Gamma Camera Uniformity, Brad K. Lofton

Dissertations and Theses (Open Access)

Detector uniformity is a fundamental performance characteristic of all modern gamma camera systems, and ensuring a stable, uniform detector response is critical for maintaining clinical images that are free of artifact. For these reasons, the assessment of detector uniformity is one of the most common activities associated with a successful clinical quality assurance program in gamma camera imaging. The evaluation of this parameter, however, is often unclear because it is highly dependent upon acquisition conditions, reviewer expertise, and the application of somewhat arbitrary limits that do not characterize the spatial location of the non-uniformities. Furthermore, as the goal of any …

Hyperpolarized (3)He Magnetic Resonance Imaging-Derived Pulmonary Pressure-Volume Curves, Stephen Choy, Andrew Wheatley, David G Mccormack, Grace Parraga

Medical Biophysics Publications

We aimed to evaluate the potential for the use of hyperpolarized helium-3 magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) surrogates of alveolar size, together with literature-based morphological parameters in a theoretical model of lung mechanics to simulate noninvasive transpulmonary pressure-volume curves. Fourteen ex-smokers with chronic obstructive pulmonary disease (COPD) (n = 8 stage II, n = 6 stage III/IV COPD) and five age-matched never-smokers, provided written, informed consent and were evaluated at baseline and 26 + or - 2 mo later (n = 15 subjects) using plethysmography, spirometry, and (3)He MRI at 3.0 T. Total lung capacity, residual volume, …

Volumetric Modulated Arc Therapy Evaluation With The Radiological Physics Center Head And Neck Phantom, Kelly Kisling

Dissertations and Theses (Open Access)

Validation of treatment plan quality and dose calculation accuracy is essential for new radiotherapy techniques, including volumetric modulated arc therapy (VMAT). VMAT delivers intensity modulated radiotherapy treatments while simultaneously rotating the gantry, adding an additional level of complexity to both the dose calculation and delivery of VMAT treatments compared to static gantry IMRT. The purpose of this project was to compare two VMAT systems, Elekta VMAT and Varian RapidArc, to the current standard of care, IMRT, in terms of both treatment plan quality and dosimetric delivery accuracy using the Radiological Physics Center (RPC) head and neck (H&N) phantom. Clinically relevant …

Chronic Obstructive Pulmonary Disease: Longitudinal Hyperpolarized (3)He Mr Imaging, Miranda Kirby, Lindsay Mathew, Andrew Wheatley, Giles E Santyr, David G Mccormack, Grace Parraga

Medical Biophysics Publications

PURPOSE: To quantitatively evaluate a small pilot group of ex-smokers with chronic obstructive pulmonary disease (COPD) and healthy volunteers during approximately 2 years by using hyperpolarized helium 3 ((3)He) magnetic resonance (MR) imaging.

MATERIALS AND METHODS: All subjects provided written informed consent to the study protocol, which was approved by the local research ethics board and Health Canada and was compliant with the Personal Information Protection and Electronic Documents Act and HIPAA. Hyperpolarized (3)He MR imaging, hydrogen 1 MR imaging, spirometry, and plethysmography were performed in 15 ex-smokers with COPD and five healthy volunteers (with the same mean age and …

Prostaglandin E(2) Is Crucial In The Response Of Podocytes To Fluid Flow Shear Stress., Tarak Srivastava, Ellen T. Mccarthy, Ram Sharma, Patricia A. Cudmore, Mukut Sharma, Mark L. Johnson, Lynda F. Bonewald

Manuscripts, Articles, Book Chapters and Other Papers

Podocytes play a key role in maintaining and modulating the filtration barrier of the glomerulus. Because of their location, podocytes are exposed to mechanical strain in the form of fluid flow shear stress (FFSS). Several human diseases are characterized by glomerular hyperfiltration, such as diabetes mellitus and hypertension. The response of podocytes to FFSS at physiological or pathological levels is not known. We exposed cultured podocytes to FFSS, and studied changes in actin cytoskeleton, prostaglandin E(2) (PGE(2)) production and expression of cyclooxygenase-1 and-2 (COX-1, COX-2). FFSS caused a reduction in transversal F-actin stress filaments and the appearance of cortical actin …

Measurement Of The Vascular Input Function In Mice For Dce-Mri, Dustin K. Ragan

Dissertations and Theses (Open Access)

DCE-MRI is an important technique in the study of small animal cancer models because its sensitivity to vascular changes opens the possibility of quantitative assessment of early therapeutic response. However, extraction of physiologically descriptive parameters from DCE-MRI data relies upon measurement of the vascular input function (VIF), which represents the contrast agent concentration time course in the blood plasma. This is difficult in small animal models due to artifacts associated with partial volume, inflow enhancement, and the limited temporal resolution achievable with MR imaging. In this work, the development of a suite of techniques for high temporal resolution, artifact resistant …

Thoracic Radiotherapy Treatment Planning With Cine Pet/Ct, Adam C. Riegel

Dissertations and Theses (Open Access)

Purpose: Respiratory motion causes substantial uncertainty in radiotherapy treatment planning. Four-dimensional computed tomography (4D-CT) is a useful tool to image tumor motion during normal respiration. Treatment margins can be reduced by targeting the motion path of the tumor. The expense and complexity of 4D-CT, however, may be cost-prohibitive at some facilities. We developed an image processing technique to produce images from cine CT that contain significant motion information without 4D-CT. The purpose of this work was to compare cine CT and 4D-CT for the purposes of target delineation and dose calculation, and to explore the role of PET in target …

Schedule For Ct Image Guidance In Treating Prostate Cancer With Helical Tomotherapy., G Beldjoudi, S Yartsev, G Bauman, Jerry J. Battista Dr., Jacob Van Dyk

Oncology Publications

The aim of this study was to determine the effect of reducing the number of image guidance sessions and patient-specific target margins on the dose distribution in the treatment of prostate cancer with helical tomotherapy. 20 patients with prostate cancer who were treated with helical tomotherapy using daily megavoltage CT (MVCT) imaging before treatment served as the study population. The average geometric shifts applied for set-up corrections, as a result of co-registration of MVCT and planning kilovoltage CT studies over an increasing number of image guidance sessions, were determined. Simulation of the consequences of various imaging scenarios on the dose …

Beyond The Dvh - Spatial And Biological Radiotherapy Treatment Planning, Bo Zhao

Wayne State University Dissertations

Purpose: Both spatial and biological information are necessary in order to perform true optimization of a treatment plan and for predicting clinical outcome. The goal of this work is to develop an enhanced treatment plan evaluation tool which incorporates biological parameters and retains spatial dose information.

Methods: A software system named SABER (Spatial And Biological Evaluation for Radiotherapy) is developed which provides biological plan evaluation with a novel combination of features. It incorporates hyperradiosensitivity using the induced-repair model and applies the new concept of Dose Convolution Filter (DCF) to simulate dose wash-out …

Raman Spectroscopic Modeling Of T- Lymphocyte Activation And Detection Of Acute Renal Allograft Rejection, Kristian L. Brown

Wayne State University Dissertations

ABSTRACT

RAMAN SPECTROSCOPIC MODELING OF T-LYMPHOCYTE ACTIVATION AND DETECTION OF ACUTE RENAL ALLOGRAFT REJECTION

By

KRISTIAN L. BROWN

2010

Advisor: Gregory Auner, PhD

Major: Biomedical Engineering

Degree: Doctor of Philosophy

Despite the advances made in the area of kidney transplantation, the disparity between the demand and available donated organs remains a dominant and unresolved issue. Given the paucity of available renal allografts the preservation of existing grafts is vital. One factor that has negatively impacted renal allograft survival is acute rejection (AR). Traditionally, kidney transplant centers have used elevations in serum creatinine as a screening tool for detecting AR. However, …

The Effects Of Field-Of-View And Patient Size On Ct Numbers From Cone-Beam Computed Tomography., Katrina Y T Seet, Arvand Barghi, Slav Yartsev, Jacob Van Dyk

Oncology Publications

Cone-beam computed tomography (CBCT) is used for patient alignment before treatment and is ideal for use in adaptive radiotherapy to account for tumor shrinkage, organ deformation and weight loss. However, CBCT images are prone to artifacts such as streaking and cupping effects, reducing image quality and CT number accuracy. Our goal was to determine the optimum combination of cone-beam imaging options to increase the accuracy of image CT numbers. Several phantoms with and without inserts of known relative electron densities were imaged using the Varian on-board imaging system. It was found that CT numbers are most influenced by the selection …