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PURPOSE: Although several metal artifact reduction (MAR) algorithms for computed tomography (CT) scanning are commercially available, no quantitative, rigorous, and reproducible method exists for assessing their performance. The lack of assessment methods poses a challenge to regulators, consumers, and industry. We explored a phantom-based framework for assessing an important aspect of MAR performance: how applying MAR in the presence of metal affects model observer performance at a low-contrast detectability (LCD) task This work is, to our knowledge, the first model observer-based framework for the evaluation of MAR algorithms in the published literature. METHODS: We designed a numerical head phantom with metal implants. In order to incorporate an element of randomness, the phantom included a rotatable inset with an inhomogeneous background. We generated simulated projection data for the phantom. We applied two variants of a simple MAR algorithm, sinogram inpainting, to the projection data, that we reconstructed using filtered backprojection. To assess how MAR affected observer performance, we examined the detectability of a signal at the center of a region of interest (ROI) by a channelized Hotelling observer (CHO). As a figure of merit, we used the area under the ROC curve (AUC). RESULTS: We used simulation to test our framework on two variants of the MAR technique of sinogram inpainting. We found that our method was able to resolve the difference in two different MAR algorithms' effect on LCD task performance, as well as the difference in task performances when MAR was applied, vs not. CONCLUSION: We laid out a phantom-based framework for objective assessment of how MAR impacts low-contrast detectability, that we tested on two MAR algorithms. Our results demonstrate the importance of testing MAR performance over a range of object and imaging parameters, since applying MAR does not always improve the quality of an image for a given diagnostic task. Our framework is an initial step toward developing a more comprehensive objective assessment method for MAR, which would require developing additional phantoms and methods specific to various clinical applications of MAR, and increasing study efficiency.
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Artefactos , Tomografía Computarizada por Rayos X , Algoritmos , Metales , Fantasmas de ImagenRESUMEN
BACKGROUND AND PURPOSE: Impaired bulbar functions of speech and swallowing are among the most serious consequences of amyotrophic lateral sclerosis (ALS). Despite this, clinical trials in ALS have rarely emphasized bulbar function as an endpoint. The rater-administered Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) or various quality-of-life measures are commonly used to measure symptomatic benefit. Accordingly, we sought to evaluate the utility of measures specific to bulbar function in ALS. METHODS: We assessed bulbar functions in 120 patients with ALS, with clinicians first making direct observations of the degree of speech, swallowing and salivation impairment in these subjects. Clinical diagnosis of bulbar impairment was then compared with ALSFRS-R scores, speech rate, time to swallow liquids and solids, and scores obtained when patients completed visual analog scales (VASs) and the newly-developed 21-question self-administered Center for Neurologic Study Bulbar Function Scale (CNS-BFS). RESULTS: The CNS-BFS, ALSFRS-R, VAS and timed speech and swallowing were all concordant with clinician diagnosis. The self-report CNS-BFS and ALSFRS-R bulbar subscale best predicted clinician diagnosis with misclassification rates of 8% and 14% at the optimal cut-offs, respectively. In addition, the CNS-BFS speech and swallowing subscales outperformed both the bulbar component of the ALSFRS-R and speech and swallowing VASs when correlations were made between these scales and objective measures of timed reading and swallowing. CONCLUSIONS: Based on these findings and its relative ease of administration, we conclude that the CNS-BFS is a useful metric for assessing bulbar function in patients with ALS.
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Esclerosis Amiotrófica Lateral/diagnóstico , Deglución/fisiología , Habla/fisiología , Anciano , Esclerosis Amiotrófica Lateral/fisiopatología , Autoevaluación Diagnóstica , Femenino , Humanos , Masculino , Persona de Mediana Edad , Calidad de VidaRESUMEN
AIMS: To summarize evidence from and assess the quality of published systematic reviews evaluating the safety, efficacy and effectiveness of incretin-based medications used in the treatment of type 2 diabetes. METHODS: We identified systematic reviews of randomized controlled trials or observational studies published in any language that evaluated the safety and/or effectiveness of glucagon-like peptide-1 (GLP-1) receptor agonists or dipeptidyl-peptidase-4 (DPP-4) inhibitors. Data sources used include the Cochrane Library, PubMed, EMBASE, Web of Science, International Pharmaceutical Abstracts, table of contents of diabetes journals, and hand-searching of reference lists and clinical practice guidelines. The methodological quality of systematic reviews was independently assessed by two reviewers using the Assessment of Multiple Systematic Reviews (AMSTAR) checklist. Our study protocol was registered with PROSPERO (2013:CRD42013005149). The primary outcomes were pooled treatment effect estimates for glycaemic control, macrovascular and microvascular complications, and hypoglycaemic events. RESULTS: We identified 467 unique citations of which 84 systematic reviews met our inclusion criteria. There were 51 reviews that evaluated GLP-1 receptor agonists and 64 reviews that evaluated DPP-4 inhibitors. The median (interquartile range) AMSTAR score was 6 (3) out of 11 for quantitative and 1 (1) for non-quantitative reviews. Among the 66 quantitative systematic reviews, there were a total of 718 pooled treatment effect estimates reported for our primary outcomes and 1012 reported pooled treatment effect estimates for secondary outcomes. CONCLUSIONS: Clinicians and policy makers, when using the results of systematic reviews to inform decision-making with regard to round clinical care or healthcare policies for incretin-based medications, should consider the variability in quality of reviews.
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Diabetes Mellitus Tipo 2/tratamiento farmacológico , Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Receptor del Péptido 1 Similar al Glucagón/agonistas , Incretinas/uso terapéutico , Literatura de Revisión como Asunto , Humanos , Estudios Observacionales como Asunto , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
PURPOSE: Iterative reconstruction (IR) algorithms have the potential to reduce radiation dose in CT diagnostic imaging. As these algorithms become available on the market, a standardizable method of quantifying the dose reduction that a particular IR method can achieve would be valuable. Such a method would assist manufacturers in making promotional claims about dose reduction, buyers in comparing different devices, physicists in independently validating the claims, and the United States Food and Drug Administration in regulating the labeling of CT devices. However, the nonlinear nature of commercially available IR algorithms poses challenges to objectively assessing image quality, a necessary step in establishing the amount of dose reduction that a given IR algorithm can achieve without compromising that image quality. This review paper seeks to consolidate information relevant to objectively assessing the quality of CT IR images, and thereby measuring the level of dose reduction that a given IR algorithm can achieve. METHODS: The authors discuss task-based methods for assessing the quality of CT IR images and evaluating dose reduction. RESULTS: The authors explain and review recent literature on signal detection and localization tasks in CT IR image quality assessment, the design of an appropriate phantom for these tasks, possible choices of observers (including human and model observers), and methods of evaluating observer performance. CONCLUSIONS: Standardizing the measurement of dose reduction is a problem of broad interest to the CT community and to public health. A necessary step in the process is the objective assessment of CT image quality, for which various task-based methods may be suitable. This paper attempts to consolidate recent literature that is relevant to the development and implementation of task-based methods for the assessment of CT IR image quality.
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Algoritmos , Tomografía Computarizada por Rayos X/métodos , Humanos , Modelos Teóricos , Fantasmas de Imagen , Dosis de Radiación , Tomografía Computarizada por Rayos X/instrumentación , Tomografía Computarizada por Rayos X/normasRESUMEN
The US Food and Drug Administration (FDA) is committed to working with the oncology community to expedite the drug evaluation process in view of the many promising new oncology drugs under laboratory development and the time and expense required for such new drugs to reach the patient population. One significant advance would be to enable quantitative imaging as a tumor biomarker. The FDA is working with the pharmaceutical industry, academia, and sister stakeholders in the government, primarily through collaborative educational and research efforts, to identify how imaging can serve this function.
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Diagnóstico por Imagen , Neoplasias Pulmonares/diagnóstico por imagen , Neoplasias Pulmonares/patología , United States Food and Drug Administration , Antineoplásicos/uso terapéutico , Ensayos Clínicos como Asunto , Aprobación de Drogas , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , National Institutes of Health (U.S.) , Fantasmas de Imagen , Pronóstico , Proyectos de Investigación , Programas Informáticos/normas , Tomografía Computarizada por Rayos X/instrumentación , Tomografía Computarizada por Rayos X/normas , Estados UnidosRESUMEN
In the past decade, there has been a vast increase in the amount of gene sequence information that has the potential to revolutionize the way diseases are both categorized and treated. Old diagnoses, largely anatomical or descriptive in nature, are likely to be superceded by the molecular characterization of the disease. The recognition that certain genes drive key disease processes will also enable the rational design of gene-specific therapeutics. Antisense oligonucleotides represent a technology that should play multiple roles in this process.
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Oligonucleótidos Antisentido , Animales , Humanos , Oligonucleótidos Antisentido/síntesis química , ARN Mensajero/biosíntesis , ARN Mensajero/genéticaRESUMEN
A minimum-norm least-squares image-reconstruction method for the reconstruction of magnetic resonance images from non-Cartesian sampled data is proposed. The method is based on a general formalism for continuous-to-discrete mapping and pseudoinverse calculation. It does not involve any regridding or interpolation of the data and therefore the methodology differs fundamentally from existing regridding-based methods. Moreover, the method uses a continuous representation of objects in the image domain instead of a discretized representation. Simulations and experiments show the possibilities of the method in both radial and spiral imaging. Simulations revealed that minimum-norm least-squares image reconstruction can result in a drastic decrease of artifacts compared with regridding-based reconstruction. Besides, both in vivo and phantom experiments showed that minimum-norm least-squares image reconstruction leads to contrast improvement and increased signal-to-noise ratio compared with image reconstruction based on regridding. As an appendix, an analytical calculation of the raw data corresponding to the well-known Shepp and Logan software head phantom is presented.
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Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética , HumanosAsunto(s)
Infecciones Oportunistas Relacionadas con el SIDA/complicaciones , Ceguera/etiología , Neoplasias de la Coroides/complicaciones , Retinitis por Citomegalovirus/complicaciones , Melanoma/complicaciones , Infecciones Oportunistas Relacionadas con el SIDA/diagnóstico , Anciano , Ceguera/diagnóstico , Neoplasias de la Coroides/diagnóstico , Retinitis por Citomegalovirus/diagnóstico , Estudios de Seguimiento , Humanos , Masculino , Melanoma/diagnóstico , Persona de Mediana Edad , Desprendimiento de Retina/complicaciones , Desprendimiento de Retina/diagnóstico , Agudeza VisualAsunto(s)
Vértebras Cervicales/lesiones , Cefalalgia Histamínica/complicaciones , Síndrome de Horner/etiología , Traumatismos del Cuello/complicaciones , Accidentes de Tránsito , Adulto , Síndrome de Horner/diagnóstico , Humanos , Vértebras Lumbares/lesiones , Masculino , Traumatismos Vertebrales/complicaciones , Osteofitosis Vertebral/complicaciones , Agudeza VisualAsunto(s)
Oclusión de la Arteria Retiniana/etiología , Tromboembolia/complicaciones , Adulto , Estenosis Carotídea/complicaciones , Estenosis Carotídea/diagnóstico , Estenosis Carotídea/cirugía , Endarterectomía Carotidea , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Oclusión de la Arteria Retiniana/diagnóstico , Oclusión de la Arteria Retiniana/prevención & control , Tromboembolia/diagnóstico , Tromboembolia/cirugía , Agudeza Visual , Campos VisualesAsunto(s)
Excipientes , Enfermedades de la Retina/inducido químicamente , Abuso de Sustancias por Vía Intravenosa/complicaciones , Talco , Analgésicos Opioides , Angiografía con Fluoresceína , Fondo de Ojo , Humanos , Masculino , Meperidina , Persona de Mediana Edad , Enfermedades de la Retina/diagnóstico , Vasos Retinianos/efectos de los fármacos , Vasos Retinianos/patología , Agudeza VisualRESUMEN
Systemically administered interleukin (IL)-12 causes liver inflammation in mice characterized by Kupffer cell proliferation and hypertrophy, hepatocyte necrosis, and multifocal accumulations of leukocytes in the hepatic parenchyma and around portal tracts and central veins. We have used both immunohistochemical staining and radiolabeled antibody quantitation to examine adhesion molecule expression in the livers of mice dosed daily with murine IL-12. Cells infiltrating livers of IL-12-treated mice were primarily mononuclear leukocytes expressing LFA-1, VLA-4, MAC-1, and CD18 adhesion molecules but little L-selectin. Kupffer cells constitutively expressed LFA-1 and smaller amounts of MAC-1, and high levels of ICAM-1 were constitutively expressed by liver sinusoidal lining cells, portal tract, and central vein endothelia. With IL-12 treatment, existing ICAM-1 expression was up-regulated and de novo expression occurred along bile duct epithelia. VCAM-1 levels were dramatically increased, with induced expression occurring along portal tract and central vein endothelia and scattered bile duct epithelial cells and in aggregations of cells in perivascular areas and the liver parenchyma. Although constitutive expression of E- and P-selectin was negligible, Il-12 induced a moderate rise in E-selectin levels. These increases in adhesion molecule expression may have implications for the therapeutic use of IL-12, especially in patients with liver disease or autoimmune conditions where augmented adhesion molecule expression may be critical to disease pathogenesis.
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Moléculas de Adhesión Celular/metabolismo , Interleucina-12/farmacología , Hígado/efectos de los fármacos , Hígado/metabolismo , Animales , Endotelio Vascular/metabolismo , Femenino , Inmunohistoquímica , Molécula 1 de Adhesión Intercelular/metabolismo , Leucocitos/clasificación , Leucocitos/metabolismo , Leucocitos/patología , Hígado/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Selectinas/metabolismo , Molécula 1 de Adhesión Celular Vascular/metabolismoRESUMEN
The method of constrained reconstruction, previously applied to magnetic resonance imaging (MRI), is extended to magnetic resonance spectroscopy. This method assumes a model for the MR signal. The model parameters are estimated directly from the phase encoded data. This process obviates the need for the fast Fourier transform (FFT) (which often exhibits limited resolution and ringing artifact). The technique is tested on simulated data, phantom data, and data acquired from human liver in vivo. In each case, constrained reconstruction offers spatial resolution superior to that obtained with the FFT.
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Procesamiento de Imagen Asistido por Computador/métodos , Espectroscopía de Resonancia Magnética , Artefactos , Simulación por Computador , Análisis de Fourier , Humanos , Hígado/metabolismo , Imagen por Resonancia Magnética , Modelos Químicos , Músculo Esquelético/metabolismo , Fantasmas de Imagen , Fosfatos/química , Fosfocreatina/metabolismo , Isótopos de FósforoRESUMEN
Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system (CNS) induced in rodents by activated CD4+ T cells specific for various myelin proteins such as myelin basic protein and proteolipid protein. The disease is characterized by breach of the blood-brain barrier, perivascular infiltration of leukocytes into the CNS, local inflammation and demyelination in the form of plaques. In this study, we evaluated the effect of administration of antibodies to two members of the beta 2 integrin sub-family of adhesion molecules, CD11a and CD11b, on the onset and progression of EAE. CD11a and CD11b are involved in cell-cell interactions leading to T cell and macrophage extravasation to inflammatory sites and T cell activation. Our results show that anti-CD11a antibodies could completely block the induction of EAE and anti-CD11b antibodies significantly delayed the onset and diminished the severity of clinical signs of EAE even when injections were initiated at the first appearance of clinical signs.
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Anticuerpos Monoclonales/uso terapéutico , Encefalomielitis Autoinmune Experimental/terapia , Antígeno-1 Asociado a Función de Linfocito/fisiología , Antígeno de Macrófago-1/fisiología , Secuencia de Aminoácidos , Animales , Femenino , Molécula 1 de Adhesión Intercelular/fisiología , Ratones , Datos de Secuencia MolecularRESUMEN
Consensus has been developing over the past few decades on a number of measurements required for the laboratory assessment of medical imaging modalities. Nevertheless, understanding of the connection between these measurements and human observer performance in a broad range of tasks remains far from complete. Focusing primarily on projection radiography to provide concrete examples, this overview indicates areas in which consensus on methodology for physical image-quality measurement has been established. Concepts such as "noise equivalent quanta" (NEQ) and "detective quantum efficiency" (DQE) have been found useful for normalizing physical measurements on an absolute scale and for relating those measurements to the decision performance of a hypothetical "ideal observer" that effectively performs decision tasks from the image data. The connection between ideal observer performance and human performance, as determined by receiver operating characteristic (ROC) analysis, remains to be understood for many clinically relevant tasks.
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Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Fenómenos Biofísicos , Biofisica , Estudios de Evaluación como Asunto , Humanos , Curva ROC , Intensificación de Imagen Radiográfica/métodosRESUMEN
The Division of Emergency Medicine at the University of Florida coordinates a unique program with the NASA John F. Kennedy Space Center (KSC) to provide emergency medical support (EMS) for the United States Space Transportation System. This report outlines the organization of the KSC EMS system, training received by physicians providing medical support, logistic and operational aspects of the mission, and experiences of team members. The participation of emergency physicians in support of manned space flight represents another way that emergency physicians provide leadership in prehospital care and disaster management.
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Medicina Aeroespacial/educación , Medicina Aeroespacial/organización & administración , Educación Médica Continua/organización & administración , Medicina de Emergencia/educación , Medicina de Emergencia/organización & administración , Curriculum , Planificación en Desastres/organización & administración , Florida , Humanos , Medicina del Trabajo/educación , Medicina del Trabajo/organización & administración , Estados Unidos , United States National Aeronautics and Space AdministrationRESUMEN
Figures of merit for image quality are derived on the basis of the performance of mathematical observers on specific detection and estimation tasks. The tasks include detection of a known signal superimposed on a known background, detection of a known signal on a random background, estimation of Fourier coefficients of the object, and estimation of the integral of the object over a specified region of interest. The chosen observer for the detection tasks is the ideal linear discriminant, which we call the Hotelling observer. The figures of merit are based on the Fisher information matrix relevant to estimation of the Fourier coefficients and the closely related Fourier crosstalk matrix introduced earlier by Barrett and Gifford [Phys. Med. Biol. 39, 451 (1994)]. A finite submatrix of the infinite Fisher information matrix is used to set Cramer-Rao lower bounds on the variances of the estimates of the first N Fourier coefficients. The figures of merit for detection tasks are shown to be closely related to the concepts of noise-equivalent quanta (NEQ) and generalized NEQ, originally derived for linear, shift-invariant imaging systems and stationary noise. Application of these results to the design of imaging systems is discussed.
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Simulación por Computador , Procesamiento de Imagen Asistido por Computador/métodos , Modelos Biológicos , Análisis de Fourier , HumanosRESUMEN
INTRODUCTION: Flight crew perceptions of the effect of the rotary-wing environment on patient-care capabilities have not been subject to statistical analysis. We hypothesized that flight crew members perceived significant difficulties in performing patient-care tasks during air medical transport. METHODS: A survey was distributed to a convenience sample of flight crew members from 20 flight programs. Respondents were asked to compare the difficulty of performing patient-care tasks in rotary-wing and standard (emergency department or intensive care unit) settings. Demographic data collected on respondents included years of flight experience, flights per month, crew duty position and primary aircraft in which the respondent worked. Statistical analysis was performed as appropriate using Student's t-test, type III sum of squares, and analysis of variance. Alpha was defined as p < 0.05. RESULTS: Fifty-five percent of programs (90 individuals) responded. All tasks were significantly rated more difficult in the rotary-wing environment. Ratings were not significantly correlated with flight experience, duty position, flights per month or aircraft used. CONCLUSIONS: We conclude that the performance of patient-care tasks are perceived by air medical flight crew to be significantly more difficult during rotary-wing air medical transport than in hospital settings.