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1.
Osteoporos Int ; 29(1): 153-162, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29032384

RESUMEN

A considerable proportion of stroke survivors are prescribed with proton pump inhibitors (PPIs). Our study indicated that PPI use is associated with an increased risk of osteoporosis, hip fracture, and vertebral fracture in stroke patients. The risk tends to increase as the cumulative doses of PPIs increase. INTRODUCTION: A considerable proportion of stroke survivors are prescribed with proton pump inhibitors (PPIs). Our study investigated the association between PPI use and the risk of osteoporosis and fracture among stroke survivors. METHODS: A population-based propensity-matched retrospective cohort study was conducted using the National Health Insurance Research Database in Taiwan. Patients diagnosed with a new stroke between 2000 and 2012 were identified. After propensity score matching, 10,596 patients were enrolled, and 5298 patients were each assigned to the PPI user and non-user groups. Hazard ratios (HRs) were calculated for the risk of osteoporosis, hip fracture, and vertebral fractures according to PPI use or non-use. Sensitivity analyses were conducted to evaluate the dose effects of PPI. RESULTS: PPI use after stroke was associated with an increased risk of osteoporosis, hip fracture, or vertebral fracture, with an adjusted HR (aHR) of 1.28 (P < 0.001). The aHRs were also significant for each outcome: osteoporosis, 1.26 (P < 0.001); hip fracture, 1.18 (P = 0.048); vertebral fracture, 1.33 (P < 0.001). A pattern of dose effect was identified. For any event (osteoporosis/hip fracture/vertebral fracture), the aHR for PPI use of 1-90, 91-365, and > 365 cDDDs was 1.22 (P < 0.001), 1.27 (P < 0.001), and 1.66 (P < 0.001), respectively. For each outcome, the highest dose was associated with the highest risk, with aHR of 1.79 (P < 0.001), 1.41 (P = 0.039), and 1.82 (P < 0.001) for osteoporosis, hip fracture, and vertebral fracture, respectively. Age- and sex-stratified analyses revealed similar patterns. CONCLUSIONS: PPI use is associated with an increased risk of osteoporosis, hip fracture, and vertebral fracture in stroke patients.


Asunto(s)
Osteoporosis/inducido químicamente , Fracturas Osteoporóticas/inducido químicamente , Inhibidores de la Bomba de Protones/efectos adversos , Accidente Cerebrovascular/complicaciones , Adulto , Anciano , Estudios de Cohortes , Relación Dosis-Respuesta a Droga , Femenino , Fracturas de Cadera/inducido químicamente , Fracturas de Cadera/epidemiología , Humanos , Incidencia , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Osteoporosis/epidemiología , Fracturas Osteoporóticas/epidemiología , Inhibidores de la Bomba de Protones/administración & dosificación , Estudios Retrospectivos , Medición de Riesgo/métodos , Factores Socioeconómicos , Fracturas de la Columna Vertebral/inducido químicamente , Fracturas de la Columna Vertebral/epidemiología , Accidente Cerebrovascular/tratamiento farmacológico , Accidente Cerebrovascular/epidemiología , Taiwán/epidemiología
2.
Acta Orthop Belg ; 83(3): 656-662, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-29119910

RESUMEN

Ulnar shortening is a common procedure for treating ulnar wrist pain of various causes. Many tools and devices had been reported in the literature to facilitate the procedure, but not all are universally available. Freehand technique is still useful in clinical practice. Here we present a pre-drilled hole method to improve the outcomes of the freehand technique. From 2008 to 2012, a total of 51 patients at our institution underwent ulnar shortening with this method, with an -average follow-up period of 24.4 months (range, 12-62 months). The average shortening length was 4.6 mm (range, 3-8.5 mm). All patients had uneventful union at an average of 9.8 weeks (range, 8-14 weeks) after the surgery. All had improved functional results. All patients returned to their previous full level of work and activities. The pre-drilled hole method for ulnar shortening is an easy assist to the freehand technique. Also, the union rate is high, and complications are uncommon.


Asunto(s)
Artralgia/cirugía , Osteotomía/métodos , Articulación de la Muñeca/cirugía , Estudios de Seguimiento , Humanos , Resultado del Tratamiento , Cúbito
3.
Thorac Cardiovasc Surg ; 59(4): 255-6, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21409752

RESUMEN

Pulmonary tuberculosis (TB) is a medical and social problem, particularly in developing countries. Early diagnosis and treatment is important. Chest radiography is usually the first diagnostic tool when there is a suspicion of pulmonary TB. A computed tomography (CT) scan provides more accurate information on the extent and distribution of pulmonary TB. We present here a young, immunocompetent male patient with unusual imaging findings for pulmonary TB. We discuss the clinical presentation and management.


Asunto(s)
Quistes/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Tuberculoma/diagnóstico por imagen , Tuberculosis Pulmonar/diagnóstico por imagen , Antituberculosos/uso terapéutico , Terapia Combinada , Quistes/inmunología , Quistes/microbiología , Quistes/terapia , Quimioterapia Combinada , Humanos , Inmunocompetencia , Masculino , Mycobacterium tuberculosis/aislamiento & purificación , Neumonectomía , Toracotomía , Resultado del Tratamiento , Tuberculoma/inmunología , Tuberculoma/microbiología , Tuberculoma/terapia , Tuberculosis Pulmonar/inmunología , Tuberculosis Pulmonar/microbiología , Tuberculosis Pulmonar/terapia , Adulto Joven
4.
Acta Chir Belg ; 110(2): 232-4, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20514842

RESUMEN

Pulmonary carcinosarcoma is a rare malignancy composed of epithelial and mesenchymal elements. In general, these neoplasms occur in older individuals at the age of 60 on average and are more commonly found in males who are heavy smokers. We report a 25-year-old male with a tumour shadow of the right middle lobe that was revealed by chest X-ray during a health checkup and was confirmed by subsequent computed tomography. The patient underwent thoracotomy with right middle lobe lobectomy. Histological examination of the resected specimen showed adenocarcinoma and undifferentiated sarcoma components. The clinical and histopathologic features of this rare tumour are discussed with a review of the literature.


Asunto(s)
Carcinosarcoma/patología , Neoplasias Pulmonares/patología , Adulto , Humanos , Masculino
5.
Radiology ; 250(1): 228-35, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-18955510

RESUMEN

PURPOSE: To collect up-to-date data in healthy children to create a digital hand atlas (DHA) that can be used to evaluate, on the basis of the Greulich and Pyle atlas method, racial differences in skeletal growth patterns of Asian, African American, white, and Hispanic children in the United States. MATERIALS AND METHODS: This retrospective study was HIPAA compliant and approved by the institutional review board. Informed consent was obtained from all subjects or their guardians. From May 1997 to March 2008, a DHA containing 1390 hand and wrist radiographs obtained in male and female Asian, African American, white, and Hispanic children with normal skeletal development was developed. The age of subjects ranged from 1 day to 18 years. Each image was read by two pediatric radiologists working independently and without knowledge of the subject's chronologic age, and evaluation was based on their experience with the Greulich and Pyle atlas. Statistical analyses were performed with the paired-samples t test and analysis of variance to study racial differences in growth patterns. P

Asunto(s)
Determinación de la Edad por el Esqueleto/estadística & datos numéricos , Asiático , Negro o Afroamericano , Desarrollo Óseo/fisiología , Mano/diagnóstico por imagen , Hispánicos o Latinos , Población Blanca , Adolescente , Determinación de la Edad por el Esqueleto/normas , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Cómputos Matemáticos , Valores de Referencia , Estudios Retrospectivos , Caracteres Sexuales , Programas Informáticos
6.
Acad Radiol ; 15(3): 290-9, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18280927

RESUMEN

RATIONALE AND OBJECTIVES: To analyze the effect of a computer-aided diagnosis (CAD) system on clinicians' performance in detection of small acute intracranial hemorrhage (AIH) on computed tomography (CT). MATERIALS AND METHODS: The authors have developed a CAD scheme that used both image processing techniques and anatomic knowledge based classification system to improve diagnosis of small AIH on CT. A multiple-reader, multiple-case receiver operating characteristic (ROC) study was performed. Twenty clinicians, including seven emergency physicians, seven radiology residents, and six radiology specialists were recruited as readers of 60 sets of brain CT, including 30 cases that show AIH smaller than 1 cm, and 30 controls. Each reader read the same 60 cases twice, first without, then with the prompts produced by the CAD system. The clinicians ranked their confidence in diagnosing a case of showing AIH, which produced the ROC curves. RESULTS: Significantly improved performance is observed in emergency physicians, average area under the ROC curve (Az) increased from 0.8422 to 0.9294 (P = .0107) when they make the diagnosis without and with the support of CAD. Az for radiology residents increased from 0.9371 to 0.9762 (P = .0088). Az for radiology specialists increased from 0.9742 to 0.9868, but was statistically insignificant (P = .1755). CONCLUSIONS: CAD can improve the clinicians' performance in detecting AIH on CT. In particular, emergency physicians can benefit most from the CAD and improve their performance to a level approaching that of the average radiology residents.


Asunto(s)
Competencia Clínica , Diagnóstico por Computador , Hemorragias Intracraneales/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Enfermedad Aguda , Algoritmos , Área Bajo la Curva , Medicina de Emergencia , Humanos , Interpretación de Imagen Asistida por Computador , Procesamiento de Imagen Asistido por Computador/métodos , Internado y Residencia , Bases del Conocimiento , Variaciones Dependientes del Observador , Curva ROC , Radiología/educación , Sensibilidad y Especificidad
7.
Curr Biol ; 10(6): 329-32, 2000 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-10744974

RESUMEN

Cdc15p is an essential protein kinase and functions with a group of late mitotic proteins that includes Lte1p, Tem1p, Cdc14p and Dbf2p/Dbf20p to inactivate Cdc28p-Clb2p at the end of mitosis in budding yeast [1] [2]. Cdc14p is activated and released from the nucleolus at late anaphase/telophase to dephosphorylate important regulators of Cdc28p-Clb2p such as Hct1p/Cdh1p, Sic1p and Swi5p in a CDC15-dependent manner [3] [4] [5] [6] [7]. How Cdc15p itself is regulated is not known. Here, we report that both the phosphorylation and localization of Cdc15p are cell cycle regulated. The extent of phosphorylation of Cdc15p gradually increases during cell-cycle progression until some point during late anaphase/telophase when it is rapidly dephosphorylated. We provide evidence suggesting that Cdc14p is the phosphatase responsible for the dephosphorylation of Cdc15p. Using a Cdc15p fusion protein coupled at its carboxyl terminus to green fluorescent protein (GFP), we found that Cdc15p, like its homologue Cdc7p [8] in fission yeast, localizes to the spindle pole bodies (SPBs) during mitosis. At the end of telophase, a portion of Cdc15p is located at the mother-bud neck, suggesting a possible role for Cdc15p in cytokinesis.


Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas de Unión al GTP/metabolismo , Proteínas Quinasas/metabolismo , Proteínas Tirosina Fosfatasas , Proteínas de Saccharomyces cerevisiae , Huso Acromático/metabolismo , Ciclo Celular , Mitosis/fisiología , Fosfoproteínas Fosfatasas/metabolismo , Fosforilación , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
8.
Mol Cell Biol ; 18(2): 665-75, 1998 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9447962

RESUMEN

The HIS4 gene in Saccharomyces cerevisiae was put under the transcriptional control of RNA polymerase I to determine the in vivo consequences on mRNA processing and gene expression. This gene, referred to as rhis4, was substituted for the normal HIS4 gene on chromosome III. The rhis4 gene transcribes two mRNAs, of which each initiates at the polymerase (pol) I transcription initiation site. One transcript, rhis4s, is similar in size to the wild-type HIS4 mRNA. Its 3' end maps to the HIS4 3' noncoding region, and it is polyadenylated. The second transcript, rhis4l, is bicistronic. It encodes the HIS4 coding region and a second open reading frame, YCL184, that is located downstream of the HIS4 gene and is predicted to be transcribed in the same direction as HIS4 on chromosome III. The 3' end of rhis4l maps to the predicted 3' end of the YCL184 gene and is also polyadenylated. Based on in vivo labeling experiments, the rhis4 gene appears to be more actively transcribed than the wild-type HIS4 gene despite the near equivalence of the steady-state levels of mRNAs produced from each gene. This finding indicated that rhis4 mRNAs are rapidly degraded, presumably due to the lack of a cap structure at the 5' end of the mRNA. Consistent with this interpretation, a mutant form of XRN1, which encodes a 5'-3' exonuclease, was identified as an extragenic suppressor that increases the half-life of rhis4 mRNA, leading to a 10-fold increase in steady-state mRNA levels compared to the wild-type HIS4 mRNA level. This increase is dependent on pol I transcription. Immunoprecipitation by anticap antiserum suggests that the majority of rhis4 mRNA produced is capless. In addition, we quantitated the level of His4 protein in a rhis4 xrn1delta genetic background. This analysis indicates that capless mRNA is translated at less than 10% of the level of translation of capped HIS4 mRNA. Our data indicate that polyadenylation of mRNA in yeast occurs despite HIS4 being transcribed by RNA polymerase I, and the 5' cap confers stability to mRNA and affords the ability of mRNA to be translated efficiently in vivo.


Asunto(s)
Proteínas Fúngicas/biosíntesis , Complejos Multienzimáticos/biosíntesis , Biosíntesis de Proteínas , ARN Polimerasa I/metabolismo , ARN Mensajero/metabolismo , Proteínas de Saccharomyces cerevisiae , Factores de Transcripción/biosíntesis , Oxidorreductasas de Alcohol , Aminohidrolasas , Secuencia de Bases , ADN de Hongos/metabolismo , ADN Ribosómico/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Exorribonucleasas/genética , Exorribonucleasas/metabolismo , Datos de Secuencia Molecular , Mutagénesis , Pirofosfatasas , ARN Polimerasa II/metabolismo , Saccharomyces cerevisiae/genética , Transcripción Genética
9.
Acad Radiol ; 14(3): 270-8, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17307659

RESUMEN

RATIONALE AND OBJECTIVES: Most health care facilities currently struggle with protecting medical data privacy, misidentification of patients, and long patient waiting times. This article demonstrates a novel system for a clinical environment using wireless tracking and facial biometric technologies to automatically monitor and identify staff and patients to address these problems. MATERIALS AND METHODS: The design of the location tracking and verification system (LTVS) was based on a workflow study which was performed to observe the physical location and movement of patient and staff at the Healthcare Consultation Center II (HCC II) running hospital information systems, radiology information systems, picture archive and communication systems, and a voice recognition system. Based on the results from this workflow study, the LTVS was designed using a wireless real-time location system and a facial biometric system integrated with the radiology information system. The LTVS was tested for its functionality in a laboratory environment, then evaluated at HCC II. RESULTS: Experimental results in the laboratory and clinical environments demonstrated that patient and staff real-time location information and identity verification can be obtained from LTVS. Warning messages can immediately be sent to alert staff when patient's waiting time is over a predefined limit, and unauthorized access to a security area can be audited. Additionally, patient misidentification can be prevented during the course of examinations. CONCLUSIONS: The system enabled health care providers to streamline the patient workflow, protect against erroneous examinations and create a security zone to prevent, and audit unauthorized access to patient health care data required by the Health Insurance Portability and Accountability Act mandate.


Asunto(s)
Sistemas de Información en Hospital , Sistemas de Información Radiológica , Seguridad Computacional , Costos y Análisis de Costo , Sistemas de Información en Hospital/economía , Sistemas de Identificación de Pacientes , Sistemas de Información Radiológica/economía , Software de Reconocimiento del Habla
10.
Mol Biol Cell ; 11(7): 2315-25, 2000 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10888670

RESUMEN

Polyubiquitination marks proteins for degradation by the 26S proteasome and is carried out by a cascade of enzymes that includes ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s), and ubiquitin ligases (E3s). The anaphase-promoting complex or cyclosome (APC/C) comprises a multisubunit ubiquitin ligase that mediates mitotic progression. Here, we provide evidence that the Saccharomyces cerevisiae RING-H2 finger protein Apc11 defines the minimal ubiquitin ligase activity of the APC. We found that the integrity of the Apc11p RING-H2 finger was essential for budding yeast cell viability, Using purified, recombinant proteins we showed that Apc11p interacted directly with the Ubc4 ubiquitin conjugating enzyme (E2). Furthermore, purified Apc11p was capable of mediating E1- and E2-dependent ubiquitination of protein substrates, including Clb2p, in vitro. The ability of Apc11p to act as an E3 was dependent on the integrity of the RING-H2 finger, but did not require the presence of the cullin-like APC subunit Apc2p. We suggest that Apc11p is responsible for recruiting E2s to the APC and for mediating the subsequent transfer of ubiquitin to APC substrates in vivo.


Asunto(s)
Proteínas Fúngicas/metabolismo , Ligasas/metabolismo , Complejos de Ubiquitina-Proteína Ligasa , Ubiquitinas/metabolismo , Dedos de Zinc , Secuencia de Aminoácidos , Ciclosoma-Complejo Promotor de la Anafase , Animales , Subunidad Apc11 del Ciclosoma-Complejo Promotor de la Anafase , Supervivencia Celular , Proteínas Fúngicas/genética , Humanos , Ligasas/genética , Datos de Secuencia Molecular , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Enzimas Ubiquitina-Conjugadoras , Ubiquitina-Proteína Ligasas
11.
Comput Med Imaging Graph ; 31(4-5): 322-31, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17387000

RESUMEN

We have developed an automated method to assess bone age of children using a digital hand atlas. The hand atlas consists of two components. The first component is a database which is comprised of a collection of 1400 digitized left hand radiographs from evenly distributed normally developed children of Caucasian (CA), Asian (AS), African-American (AA) and Hispanic (HI) origin, male (M) and female (F), ranged from 1- to 18-year-old; and relevant patient demographic data along with pediatric radiologists' readings of each radiograph. This data is separate into eight categories: CAM, CAF, AAM, AAF, HIM, HIF, ASM, and ASF. In addition, CAM, AAM, HIM, and ASM are combined as one male category; and CAF, AAF, HIF, and ASF are combined as one female category. The male and female are further combined as the F & M category. The second component is a computer-assisted diagnosis (CAD) module to assess a child bone age based on the collected data. The CAD method is derived from features extracted from seven regions of interest (ROIs): the carpal bone ROI, and six phanlangeal PROIs. The PROIs are six areas including the distal and middle regions of three middle fingers. These features were used to train the 11 category fuzzy classifiers: one for each race and gender, one for the female, one male, and one F & M, to assess the bone age of a child. The digital hand atlas is being integrated with a PACS for validation of clinical use.


Asunto(s)
Determinación de la Edad por el Esqueleto/métodos , Huesos de la Mano/diagnóstico por imagen , Sistemas de Información Radiológica , Adolescente , Niño , Preescolar , Femenino , Trastornos del Crecimiento/diagnóstico , Huesos de la Mano/metabolismo , Humanos , Interpretación de Imagen Asistida por Computador/métodos , Lactante , Masculino , Estados Unidos
12.
Comput Med Imaging Graph ; 29(2-3): 195-202, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15755537

RESUMEN

Imaging-matching is an important research area in imaging informatics. We have developed and evaluated a novel diagnostic support tool (DST) based on medical image matching using MR brain images. The approach consists of two steps, database generation and image matching. The database contains pre-diagnosed MR brain images. As the images are added to the database, they are registered to the 3D Talairach coordinate system. In addition, regions of interests (ROI) are generated, and image-processing techniques are used to extract relevant image parameters related to the brain and diseases from the ROIs and from the entire MR image. The second step is to retrieve relevant information from the database by performing image matching. In this step, the physician first submits a query image. The DST computes the similarity between the query image and each of the images in the database, and then presents the most similar images to the user. Since the database contains pre-diagnosed images, the retrieved cases tend to contain relevant diagnostic information. To evaluate the usefulness of the DST in a clinical setting, pediatric brain diseases were used. The database contains 2500 pediatric patients between ages 0 and 18 with brain Magnetic Resonance (MR) images of known brain lesions. A testbed was established at the Children's Hospital Los Angeles (CHLA) for acquiring MR images from the PACS server of patients with known lesions. These images were matched against those in the DST pediatric brain MR database. An expert pediatric neuroradiologist evaluated the matched results. We found that in most cases, the image-matching method was able to quickly retrieve images with relevant diagnostic content. The evaluation method and results are given.


Asunto(s)
Encefalopatías/diagnóstico , Niño , Humanos , Imagen por Resonancia Magnética , Estados Unidos
14.
J Hand Surg Eur Vol ; 40(7): 735-9, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26056128

RESUMEN

UNLABELLED: We compared the short-term (3 months) and long-term (2 years) outcomes and complications of percutaneous release of 187 trigger digits of 154 patients treated between 2009 and 2012, all treated by a single surgeon. The 154 patients included 48 patients with diabetes mellitus and 106 non-diabetic patients. The only short-term complication was pain, occurring in three digits (5%) in the diabetic patients and six digits (5%) in the non-diabetic patients. The long-term complications were pain in 15 digits (25%) in the diabetic patients and 18 digits (14%) in the non-diabetic patients. This was not significant (p = 0.058). Recurrent triggering occurred in nine digits (15%) in the diabetic patients, which was significantly greater than the six digits (5%) in the non-diabetic patients (p = 0.013). The non-diabetic patients were significantly more satisfied. LEVEL OF EVIDENCE: level III.


Asunto(s)
Complicaciones de la Diabetes , Trastorno del Dedo en Gatillo/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Dolor Postoperatorio/etiología , Satisfacción del Paciente/estadística & datos numéricos , Recurrencia , Trastorno del Dedo en Gatillo/complicaciones
15.
Arch Neurol ; 40(12): 715-9, 1983 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-6625982

RESUMEN

We compared the computed tomographic (CT) scans of 46 patients with dementia with those of 46 normal subjects matched for age and sex. We measured the areas subtended by the third ventricle, frontal horns, bodies of the lateral ventricles, and interhemispheric fissure as depicted in CT sections, then determined the ratio between each of those areas and the entire brain at each level. Patients with dementia had significantly larger ratios on all measures. A multivariate classification procedure showed that a composite formula of two measures, the bodies of the lateral ventricles and the interhemispheric fissure, predicted clinical status in 84% of the cases. Findings indicated that some CT measurements reflected cerebral changes associated with dementia. If appreciated in a suitable probabilistic framework, these data may be clinically useful in supporting or weakening the diagnostic hypothesis of dementia in the many cases in which diagnosis is unclear.


Asunto(s)
Demencia/diagnóstico , Tomografía Computarizada por Rayos X , Anciano , Encéfalo/diagnóstico por imagen , Femenino , Humanos , Masculino , Persona de Mediana Edad
16.
Invest Radiol ; 27(10): 856-64, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1399443

RESUMEN

RATIONALE AND OBJECTIVES: To synthesize magnetic resonance images (MRI) in real-time using a minimal data set obtained with routine clinical protocols and stored in a picture archiving and communication system (PACS) database. METHODS: Analytic solutions for T1 and T2 were obtained from a double and a single spin-echo set, with routine parameters. Analytic solutions from radio frequency-spoiled gradient-echo images, with TRs as low as 33 mseconds, also were used to synthesize gradient-echo images. RESULTS: Phantom studies showed that the errors in the synthesized images were significantly smaller than the errors in the T1- and T2-calculated images and similar to the source images. The gradient-echo images resulted in significant scan time savings. CONCLUSION: MRI synthesis from analytic solutions of T1, T2, and rho saves computational time and yields accurate values for the intrinsic parameters while allowing the use of routine clinical protocols. The availability of clinical images in the PACS database and the ability to synthesize images in real-time has allowed the development of a practical interactive teaching module.


Asunto(s)
Imagen por Resonancia Magnética/métodos , Encéfalo/anatomía & histología , Humanos , Modelos Estructurales
17.
Invest Radiol ; 27(7): 529-35, 1992 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-1644553

RESUMEN

OBJECTIVES AND RATIONALE: In a picture archiving and communication system (PACS), images are acquired from multiple modalities and displayed on an electronic workstation. Each modality has different image characteristics. This variability must be addressed before the image is displayed. METHODS: The authors developed methods to automatically process magnetic resonance (MR), computed tomographic (CT), and computed radiography (CR) images before display and subjectively evaluated their effectiveness. RESULTS: Unwanted background successfully was automatically removed from 89.5% of 615 CR images. Of 803 chest, abdomen, and hand images 93% were automatically rotated to the correct orientation. CONCLUSIONS: Automated preprocessing of PACS images can be performed successfully, improving speed and convenience for the radiologist interpreting images at an electronic workstation.


Asunto(s)
Procesamiento de Imagen Asistido por Computador , Sistemas de Información Radiológica , Imagen por Resonancia Magnética , Intensificación de Imagen Radiográfica/métodos , Tomografía Computarizada por Rayos X
18.
Invest Radiol ; 26(6): 590-7, 1991 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-1860768

RESUMEN

The experience with CR systems gained at the three institutions described in this report demonstrates numerous advantages over the conventional screen-film system. These include: (1) a reduction in the radiation exposure delivered to the patient (25% to 50%); (2) a decrease in the number of repeat examinations needed, especially in portable units where technical difficulties are common with screen-film examinations; this is attributable to the linear, wider dynamic range of CR systems compared with screen-film combinations; (3) the capability to archive electronically all images by means of a digital optical storage system; (4) automatic electronic setting of the laser scanner for the latitude and sensitivity on each image; (5) the digital images are available for transmission to all image display workstations on a local or wide-area network; and (6) the ability to adjust interactively the display parameters to best depict images and pathology as well as salvage technically suboptimal examinations. Several disadvantages of CR systems compared with conventional screen-film examinations have also been identified.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Pantallas Intensificadoras de Rayos X , Humanos , Mediciones Luminiscentes
19.
Invest Radiol ; 28(5): 398-403, 1993 May.
Artículo en Inglés | MEDLINE | ID: mdl-8496031

RESUMEN

RATIONALE AND OBJECTIVES: Digital image compression reduces the storage requirements and network traffic on picture archiving and communications systems. Full-frame bit-allocation (FFBA) is an irreversible image-compression method based on the discrete cosine transform that provides for high compression ratios with a high degree of image fidelity. METHODS: One hundred twenty-two posteroanterior chest radiographs were obtained on patients in an ambulatory patient setting, including 30 cases of interstitial lung disease, 45 images containing combinations of lung nodules (N = 37) or mediastinal masses (N = 39), and 47 normal images containing none of the pathology for which we were testing. The images were digitized (nominal 2 K x 2 K x 12-bit resolution), printed on a 35 x 35-cm hard copy format, and compressed at an approximate compression ratio of 20:1. Observer performance tests were conducted with five radiologists using receiver operating characteristics analysis on digitized uncompressed and compressed hard copy images. RESULTS: There were no significant differences between the two display conditions for the detectability of any of the thoracic abnormalities. CONCLUSIONS: Our preliminary results suggest that irreversible image compression at ratios of 20:1 may be acceptable for use in digital thoracic imaging.


Asunto(s)
Enfermedades del Mediastino/diagnóstico por imagen , Fibrosis Pulmonar/diagnóstico por imagen , Intensificación de Imagen Radiográfica/métodos , Nódulo Pulmonar Solitario/diagnóstico por imagen , Algoritmos , Humanos , Enfermedades del Mediastino/epidemiología , Fibrosis Pulmonar/epidemiología , Curva ROC , Radiografía Torácica/métodos , Sistemas de Información Radiológica , Nódulo Pulmonar Solitario/epidemiología
20.
Med Phys ; 20(1): 39-45, 1993.
Artículo en Inglés | MEDLINE | ID: mdl-8455510

RESUMEN

The dynamic range of the gray level of a digital image is limited by the noise it contains. Two statistical methods called "runs test" and "join-count statistic" are used to measure the noise level in a digital image. A residual image is formed by subtracting an original image from its smoothed version. Theoretically, the noise level in the residual image should be identical to that in the original image. The noise level is determined by examining each bit plane of the residual image individually starting from the least significant bit up to the bit plane whose statistic does not show a random pattern. Images from three digital modalities: computerized tomography, magnetic resonance, and computed radiography are used to evaluate the gray-level dynamic range. Both methods are easy to implement and fast to perform.


Asunto(s)
Intensificación de Imagen Radiográfica/métodos , Biometría/métodos , Fenómenos Biofísicos , Biofisica , Estudios de Evaluación como Asunto , Humanos , Imagen por Resonancia Magnética/estadística & datos numéricos , Tomografía Computarizada por Rayos X/estadística & datos numéricos
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