Medicine and Health Sciences Commons^™

Chronic Obstructive Pulmonary Disease: Thoracic Ct Texture Analysis And Machine Learning To Predict Pulmonary Ventilation, Andrew Westcott, Dante P I Capaldi, David G Mccormack, Aaron D Ward, Aaron Fenster, Grace Parraga

Medical Biophysics Publications

Background Fixed airflow limitation and ventilation heterogeneity are common in chronic obstructive pulmonary disease (COPD). Conventional noncontrast CT provides airway and parenchymal measurements but cannot be used to directly determine lung function. Purpose To develop, train, and test a CT texture analysis and machine-learning algorithm to predict lung ventilation heterogeneity in participants with COPD. Materials and Methods In this prospective study (

Oscillometry And Pulmonary Magnetic Resonance Imaging In Asthma And Copd, Rachel L Eddy, Andrew Westcott, Geoffrey N Maksym, Grace Parraga, Ronald J Dandurand

Medical Biophysics Publications

Developed over six decades ago, pulmonary oscillometry has re-emerged as a noninvasive and effort-independent method for evaluating respiratory-system impedance in patients with obstructive lung disease. Here, we evaluated the relationships between hyperpolarized

Oscillometry And Pulmonary Mri Measurements Of Ventilation Heterogeneity In Obstructive Lung Disease: Relationship To Quality Of Life And Disease Control, Heather M Young, Fumin Guo, Rachel L Eddy, Geoffrey Maksym, Grace Parraga

Medical Biophysics Publications

Ventilation heterogeneity is a hallmark finding in obstructive lung disease and may be evaluated using a variety of methods, including multiple-breath gas washout and pulmonary imaging. Such methods provide an opportunity to better understand the relationships between structural and functional abnormalities in the lungs, and their relationships with important clinical outcomes. We measured ventilation heterogeneity and respiratory impedance in 100 subjects [50 patients with asthma, 22 ex-smokers, and 28 patients with chronic obstructive pulmonary disease (COPD)] using oscillometry and hyperpolarized

Predictive Value For Cardiovascular Events Of Common Carotid Intima Media Thickness And Its Rate Of Change In Individuals At High Cardiovascular Risk - Results From The Prog-Imt Collaboration, Matthias W Lorenz, Lu Gao, Kathrin Ziegelbauer, Giuseppe Danilo Norata, Jean Philippe Empana, Irene Schmidtmann, Hung-Ju Lin, Stela Mclachlan, Lena Bokemark, Kimmo Ronkainen, Mauro Amato, Ulf Schminke, Sathanur R Srinivasan, Lars Lind, Shuhei Okazaki, Coen D A Stehouwer, Peter Willeit, Joseph F Polak, Helmuth Steinmetz, Dirk Sander, Holger Poppert, Moise Desvarieux, M Arfan Ikram, Stein Harald Johnsen, Daniel Staub, Cesare R Sirtori, Bernhard Iglseder, Oscar Beloqui, Gunnar Engström, Alfonso Friera, Francesco Rozza, Wuxiang Xie, Grace Parraga, Liliana Grigore, Matthieu Plichart, Stefan Blankenberg, Ta-Chen Su, Caroline Schmidt, Tomi-Pekka Tuomainen, Fabrizio Veglia, Henry Völzke, Giel Nijpels, Johann Willeit, Ralph L Sacco, Oscar H Franco, Heiko Uthoff, Bo Hedblad, Carmen Suarez, Raffaele Izzo, Dong Zhao, Thapat Wannarong, Alberico Catapano, Pierre Ducimetiere, Christine Espinola-Klein, Kuo-Liong Chien, Jackie F Price, Göran Bergström, Jussi Kauhanen, Elena Tremoli, Marcus Dörr, Gerald Berenson, Kazuo Kitagawa, Jacqueline M Dekker, Stefan Kiechl, Matthias Sitzer, Horst Bickel, Tatjana Rundek, Albert Hofman, Ellisiv B Mathiesen, Samuela Castelnuovo, Manuel F Landecho, Maria Rosvall, Rafael Gabriel, Nicola De Luca, Jing Liu, Damiano Baldassarre, Maryam Kavousi, Eric De Groot, Michiel L Bots, David N Yanez, Simon G Thompson

Medical Biophysics Publications

AIMS: Carotid intima media thickness (CIMT) predicts cardiovascular (CVD) events, but the predictive value of CIMT change is debated. We assessed the relation between CIMT change and events in individuals at high cardiovascular risk.

METHODS AND RESULTS: From 31 cohorts with two CIMT scans (total n = 89070) on average 3.6 years apart and clinical follow-up, subcohorts were drawn: (A) individuals with at least 3 cardiovascular risk factors without previous CVD events, (B) individuals with carotid plaques without previous CVD events, and (C) individuals with previous CVD events. Cox regression models were fit to estimate the hazard ratio (HR) of …

Free-Breathing Pulmonary Mr Imaging To Quantify Regional Ventilation, Dante P I Capaldi, Rachel L Eddy, Sarah Svenningsen, Fumin Guo, John S H Baxter, A Jonathan Mcleod, Parameswaran Nair, David G Mccormack, Grace Parraga

Medical Biophysics Publications

Purpose: To measure regional specific ventilation with free-breathing hydrogen 1 (1H) magnetic resonance (MR) imaging without exogenous contrast material and to investigate correlations with hyperpolarized helium 3 (3He) MR imaging and pulmonary function test measurements in healthy volunteers and patients with asthma.

Materials and Methods: Subjects underwent free-breathing 1H and static breath-hold hyperpolarized 3He MR imaging as well as spirometry and plethysmography; participants were consecutively recruited between January and June 2017. Free-breathing 1H MR imaging was performed with an optimized balanced steady-state free-precession sequence; images were retrospectively grouped into tidal inspiration or tidal expiration volumes with exponentially weighted phase interpolation. …

Mri Ventilation Abnormalities Predict Quality-Of-Life And Lung Function Changes In Mild-To-Moderate Copd: Longitudinal Tincan Study, Miranda Kirby, Rachel L Eddy, Damien Pike, Sarah Svenningsen, Harvey O Coxson, Don D Sin, David G Mccormack, Grace Parraga

Medical Biophysics Publications

CT biomarkers of emphysema (15th percentile of the CT density histogram, HU15%) and airways disease (wall thickness of airways with 10 mm internal perimeter, Pi10) have shown promise for providing prognostic information.2 Although recent data3 showed that the change in CT emphysema may be used to estimate the efficacy of therapy in patients with α-1-antitrypsin-deficiency, thus far none of the currently developed CT biomarkers have been shown to reflect changes in outcomes that are important to patients with COPD. MRI with inhaled noble gases provide highly sensitive and unique microstructural and functional information in COPD.4 MRI biomarkers of COPD are …

Usage Of Swi (Susceptibility Weighted Imaging) Acquired At 7t For Qualitative Evaluation Of Temporal Lobe Epilepsy Patients With Histopathological And Clinical Correlation: An Initial Pilot Study., Benjamin Y M Kwan, Fateme Salehi, Pavlo Ohorodnyk, Donald H Lee, Jorge G Burneo, Seyed M Mirsattari, David Steven, Robert Hammond, Terry M Peters, Ali R Khan

Brain and Mind Institute Researchers' Publications

OBJECTIVES: Ultra high field MRI at 7T is able to provide much improved spatial and contrast resolution which may aid in the diagnosis of hippocampal abnormalities. This paper presents a preliminary experience on qualitative evaluation of 7T MRI in temporal lobe epilepsy patients with a focus on comparison to histopathology.

METHODS: 7T ultra high field MRI data, using T1-weighted, T2*-weighted and susceptibility-weighted images (SWI), were acquired for 13 patients with drug resistant temporal lobe epilepsy (TLE) during evaluation for potential epilepsy surgery. Qualitative evaluation of the imaging data for scan quality and presence of hippocampal and temporal lobe abnormalities were …

Category Learning In Older Adulthood: A Study Of The Shepard, Hovland, And Jenkins (1961) Tasks., Rahel Rabi, John Paul Minda

Brain and Mind Institute Researchers' Publications

Shepard, Hovland, and Jenkins (1961) examined the categorization abilities of younger adults using tasks involving single-dimensional rule learning, disjunctive rule learning, and family resemblance learning. The current study examined category learning in older adults using this well-known category set. Older adults, like younger adults, found category tasks with a single relevant dimension the easiest to learn. In contrast to younger adults, older adults found complex disjunctive rule-based categories harder to learn than family resemblance based categories. Disjunctive rule-based category learning appeared to be the most difficult for older adults to learn because this category set placed the heaviest demands on …

Pulmonary Imaging Biomarkers Of Gas Trapping And Emphysema In Copd: (3)He Mr Imaging And Ct Parametric Response Maps, Dante P I Capaldi, Nanxi Zha, Fumin Guo, Damien Pike, David G Mccormack, Miranda Kirby, Grace Parraga

Medical Biophysics Publications

PURPOSE: To directly compare magnetic resonance (MR) imaging and computed tomography (CT) parametric response map (PRM) measurements of gas trapping and emphysema in ex-smokers both with and without chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS: Participants provided written informed consent to a protocol that was approved by a local research ethics board and Health Canada and was compliant with the HIPAA (Institutional Review Board Reg. #00000940). The prospectively planned study was performed from March 2014 to December 2014 and included 58 ex-smokers (mean age, 73 years ± 9) with (n = 32; mean age, 74 years ± 7) and …

Structural Brain Injury In Patients With Disorders Of Consciousness: A Voxel-Based Morphometry Study., Pieter Guldenmund, Andrea Soddu, Katherine Baquero, Audrey Vanhaudenhuyse, Marie-Aurélie Bruno, Olivia Gosseries, Steven Laureys, Francisco Gómez

Brain and Mind Institute Researchers' Publications

MAIN OBJECTIVE: Disorders of consciousness (DOC; encompassing coma, vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious state minus/plus (MCS-/+)) are associated with structural brain injury. The extent of this damage remains poorly understood and merits a detailed examination using novel analysis techniques. Research design/methods and procedures: This study used voxel-based morphometry (VBM) on structural magnetic resonance imaging scans of 61 patients with DOC to examine grey and white matter injury associated with DOC, time spent in DOC, aetiology and diagnosis.

MAIN OUTCOMES AND RESULTS: DOC and time spent in DOC were found to be associated with widespread structural brain injury, …

Copd: Do Imaging Measurements Of Emphysema And Airway Disease Explain Symptoms And Exercise Capacity?, Miranda Kirby, Damien Pike, Don D Sin, Harvey O Coxson, David G Mccormack, Grace Parraga

Medical Biophysics Publications

PURPOSE: To determine the role of imaging measurements of emphysema and airway disease in determining chronic obstructive pulmonary disease (COPD) symptoms and exercise limitation in patients with COPD, particularly in patients with mild-to-moderate disease.

MATERIALS AND METHODS: Participants (n = 116) with Global Initiative for Chronic Obstructive Lung Disease (GOLD) grade U (unclassified) or grade I-IV COPD provided informed consent to an ethics board-approved HIPAA-compliant protocol and underwent spirometry and plethysmography, completed the St George's Respiratory Questionnaire (SGRQ), completed a 6-minute walk test for the 6-minute walk distance (6MWD), and underwent hyperpolarized helium 3 ((3)He) magnetic resonance (MR) imaging and …

Fusion Analysis Of Functional Mri Data For Classification Of Individuals Based On Patterns Of Activation., Mahdi Ramezani, Purang Abolmaesumi, Kris Marble, Heather Trang, Ingrid Johnsrude

Brain and Mind Institute Researchers' Publications

Classification of individuals based on patterns of brain activity observed in functional MRI contrasts may be helpful for diagnosis of neurological disorders. Prior work for classification based on these patterns have primarily focused on using a single contrast, which does not take advantage of complementary information that may be available in multiple contrasts. Where multiple contrasts are used, the objective has been only to identify the joint, distinct brain activity patterns that differ between groups of subjects; not to use the information to classify individuals. Here, we use joint Independent Component Analysis (jICA) within a Support Vector Machine (SVM) classification …

Ventilation Heterogeneity In Ex-Smokers Without Airflow Limitation., Damien Pike, Miranda Kirby, Fumin Guo, David G Mccormack, Grace Parraga

Medical Biophysics Publications

RATIONALE AND OBJECTIVES: Hyperpolarized (3)He magnetic resonance imaging (MRI) ventilation abnormalities are visible in ex-smokers without airflow limitation, but the clinical relevance of this is not well-understood. Our objective was to phenotype healthy ex-smokers with normal and abnormally elevated ventilation defect percent (VDP).

MATERIALS AND METHODS: Sixty ex-smokers without airflow limitation provided written informed consent to (3)He MRI, computed tomography (CT), and pulmonary function tests in a single visit. (3)He MRI VDP and apparent diffusion coefficients (ADCs) were measured for whole-lung and each lung lobe as were CT measurements of emphysema (relative area [RA] with attenuation ≤-950 HU, RA950) and …

Deficits In Audiovisual Speech Perception In Normal Aging Emerge At The Level Of Whole-Word Recognition., Ryan A Stevenson, Caitlin E Nelms, Sarah H Baum, Lilia Zurkovsky, Morgan D Barense, Paul A Newhouse, Mark T Wallace

Brain and Mind Institute Researchers' Publications

Over the next 2 decades, a dramatic shift in the demographics of society will take place, with a rapid growth in the population of older adults. One of the most common complaints with healthy aging is a decreased ability to successfully perceive speech, particularly in noisy environments. In such noisy environments, the presence of visual speech cues (i.e., lip movements) provide striking benefits for speech perception and comprehension, but previous research suggests that older adults gain less from such audiovisual integration than their younger peers. To determine at what processing level these behavioral differences arise in healthy-aging populations, we administered …

Pulmonary Ventilation Defects In Older Never-Smokers, Khadija Sheikh, Gregory A Paulin, Sarah Svenningsen, Miranda Kirby, Nigel A M Paterson, David G Mccormack, Grace Parraga

Medical Biophysics Publications

Hyperpolarized (3)He MRI previously revealed spatially persistent ventilation defects in healthy, older compared with healthy, younger never-smokers. To understand better the physiological consequences and potential relevance of (3)He MRI ventilation defects, we evaluated (3)He-MRI ventilation-defect percent (VDP) and the effect of deep inspiration (DI) and salbutamol on VDP in older never-smokers. To identify the potential determinants of ventilation defects in these subjects, we evaluated dyspnea, pulmonary function, and cardiopulmonary exercise test (CPET) measurements, as well as occupational and second-hand smoke exposure. Fifty-two never-smokers (71 ± 6 yr) with no history of chronic respiratory disease were evaluated. During a single visit, …

Three-Dimensional Carotid Ultrasound Plaque Texture Predicts Vascular Events, Arna Van Engelen, Thapat Wannarong, Grace Parraga, Wiro J Niessen, Aaron Fenster, J David Spence, Marleen De Bruijne

Medical Biophysics Publications

BACKGROUND AND PURPOSE: Carotid ultrasound atherosclerosis measurements, including those of the arterial wall and plaque, provide a way to monitor patients at risk of vascular events. Our objective was to examine carotid ultrasound plaque texture measurements and the change in carotid plaque texture during 1 year in patients at risk of events and to compare these with measurements of plaque volume and other risk factors as predictors of vascular events.

METHODS: We evaluated 298 patients with carotid atherosclerosis using 3-dimensional (3D) ultrasound at baseline and after 1 year and measured carotid plaque volume and 376 measures of plaque texture. Patients …

Volume Of Carotid Artery Ulceration As A Predictor Of Cardiovascular Events, Mariya Kuk, Thapat Wannarong, Vadim Beletsky, Grace Parraga, Aaron Fenster, J David Spence

Medical Biophysics Publications

BACKGROUND AND PURPOSE: Previous studies have shown the presence of ulceration in atherosclerotic plaque either by categorizing the plaque as complex (irregular morphology with ulcers) or smooth or by quantifying the number of ulcers observed in a specific region of interest. The aim of this study was to quantify carotid total ulcer volume by 3-dimensional ultrasound to investigate the relationship of total ulcer volume to vascular events (strokes, transient ischemic attack, myocardial infarction, revascularization, or death because of cardiovascular reasons).

METHODS: In total, 349 at-risk subjects provided written informed consent to carotid 3-dimensional ultrasound and were analyzed for ulcerations. Ulcer …

One, Two And Three-Dimensional Ultrasound Measurements Of Carotid Atherosclerosis Before And After Cardiac Rehabilitation: Preliminary Results Of A Randomized Controlled Trial., Tamas J Lindenmaier, Daniel N Buchanan, Damien Pike, Tim Hartley, Robert D Reid, J David Spence, Richard Chan, Michael Sharma, Peter L Prior, Neville Suskin, Grace Parraga

Medical Biophysics Publications

BACKGROUND: It is still not known how patients who are post-transient ischemic attack (TIA) or post-stroke might benefit from prospectively planned comprehensive cardiac rehabilitation (CCR). In this pilot evaluation of a larger ongoing randomized-controlled-trial, we evaluated ultrasound (US) measurements of carotid atherosclerosis in subjects following TIA or mild non-disabling stroke and their relationship with risk factors before and after 6-months of CCR.

METHODS: Carotid ultrasound (US) measurements of one-dimensional intima-media-thickness (IMT), two-dimensional total-plaque-area (TPA), three-dimensional total-plaque-volume (TPV) and vessel-wall-volume (VWV) were acquired before and after 6-months CCR for 39 subjects who had previously experienced a TIA and provided written informed …

Progression Of Carotid Plaque Volume Predicts Cardiovascular Events, Thapat Wannarong, Grace Parraga, Daniel Buchanan, Aaron Fenster, Andrew A House, Daniel G Hackam, J David Spence

Medical Biophysics Publications

BACKGROUND AND PURPOSE: Carotid ultrasound evaluation of intima-media thickness (IMT) and plaque burden has been used for risk stratification and for evaluation of antiatherosclerotic therapies. Increasing evidence indicates that measuring plaque burden is superior to measuring IMT for both purposes. We compared progression/regression of IMT, total plaque area (TPA), and total plaque volume (TPV) as predictors of cardiovascular outcomes.

METHODS: IMT, TPA, and TPV were measured at baseline in 349 patients attending vascular prevention clinics; they had TPA of 40 to 600 mm(2) at baseline to qualify for enrollment. Participants were followed up for ≤5 years (median, 3.17 years) to …

On The Role Of Abnormal Dl(Co) In Ex-Smokers Without Airflow Limitation: Symptoms, Exercise Capacity And Hyperpolarised Helium-3 Mri, Miranda Kirby, Amir Owrangi, Sarah Svenningsen, Andrew Wheatley, Harvey O Coxson, Nigel A M Paterson, David G Mccormack, Grace Parraga

Medical Biophysics Publications

BACKGROUND: The functional effects of abnormal diffusing capacity for carbon monoxide (DLCO) in ex-smokers without chronic obstructive pulmonary disease (COPD) are not well understood.

OBJECTIVE: We aimed to evaluate and compare well established clinical, physiological and emerging imaging measurements in ex-smokers with normal spirometry and abnormal DLCO with a group of ex-smokers with normal spirometry and DLCO and ex-smokers with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I COPD.

METHODS: We enrolled 38 ex-smokers and 15 subjects with stage I COPD who underwent spirometry, plethysmography, St George's Respiratory Questionnaire (SGRQ), 6 min Walk Test (6MWT), x-ray CT and …

Hyperpolarized 3he And 129xe Mr Imaging In Healthy Volunteers And Patients With Chronic Obstructive Pulmonary Disease, Miranda Kirby, Sarah Svenningsen, Amir Owrangi, Andrew Wheatley, Adam Farag, Alexei Ouriadov, Giles E Santyr, Roya Etemad-Rezai, Harvey O Coxson, David G Mccormack, Grace Parraga

Medical Biophysics Publications

PURPOSE: To quantitatively compare hyperpolarized helium 3 (3He) and xenon 129 (129Xe) magnetic resonance (MR) images obtained within 5 minutes in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD) and to evaluate the correlations between 3He and 129Xe MR imaging measurements and those from spirometry and plethysmography.

MATERIALS AND METHODS: This study was approved by an ethics board and compliant with HIPAA. Written informed consent was obtained from all subjects. Eight healthy volunteers and 10 patients with COPD underwent MR imaging, spirometry, and plethysmography. Ventilation defect percentages (VDPs) at 3He and 129Xe imaging were obtained by using semiautomated …

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 …

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

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 …

The Effect Of Dopamine Therapy On Ventral And Dorsal Striatum-Mediated Cognition In Parkinson's Disease: Support From Functional Mri., Penny A Macdonald, Alex A Macdonald, Ken N Seergobin, Ruzbeh Tamjeedi, Hooman Ganjavi, Jean-Sebastien Provost, Oury Monchi

Brain and Mind Institute Researchers' Publications

The central aim of our study was to elucidate functions mediated by the ventral and dorsal striatum, respectively, to better understand the cognitive effects of dopamine replacement in Parkinson's disease. We proposed that the ventral striatum underlies general learning of stimulus associations, whereas the dorsal striatum promotes integration of various influences on selecting. In Parkinson's disease, dopamine depletion is substantially less notable in the ventral relative to the dorsal striatum, and therefore greater improvements are expected for dorsal striatum-mediated functions with dopamine replacement. Using a simple selection task, we found that dopamine replacement impaired encoding and facilitation of consistent stimulus-stimulus …

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, …

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 …

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 …

Adaptive Radiation Therapy For Localized Mesothelioma With Mediastinal Metastasis Using Helical Tomotherapy., James Renaud, Slav Yartsev, A Rashid Dar, Jacob Van Dyk

Oncology Publications

The purpose of this study was to compare 2 adaptive radiotherapy strategies with helical tomotherapy. A patient having mesothelioma with mediastinal nodes was treated using helical tomotherapy with pretreatment megavoltage CT (MVCT) imaging. Gross tumor volumes (GTVs) were outlined on every MVCT study. Two alternatives for adapting the treatment were investigated: (1) keeping the prescribed dose to the targets while reducing the dose to the OARs and (2) escalating the target dose while maintaining the original level of healthy tissue sparing. Intensity modulated radiotherapy (step-and-shoot IMRT) and 3D conformal radiotherapy (3DCRT) plans for the patient were generated and compared. The …

Scan-Rescan And Intra-Observer Variability Of Magnetic Resonance Imaging Of Carotid Atherosclerosis At 1.5 T And 3.0 T, Arvin Vidal, Yves Bureau, Trevor Wade, J David Spence, Brian K Rutt, Aaron Fenster, Grace Parraga

Medical Biophysics Publications

Carotid atherosclerosis measurements for eight subjects at baseline and 14 +/- 2 days later were examined using 1.5 T and 3.0 T magnetic resonance imaging (MRI). A single observer blinded to field strength, subject and timepoint manually segmented carotid artery wall and lumen boundaries in randomized images in five measurement trials. Mean increases in the signal-to-noise ratios (SNR) for T1-weighted images acquired at 3.0 T compared to 1.5 T were 90% (scan) and 80% (rescan). Despite significantly improved SNR and contrast-to-noise ratios (CNR) for images acquired at 3.0 T, vessel wall volume (VWV) intra-observer variability was not significantly different using …