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1.
Epilepsy Behav ; 19(3): 376-82, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20920892

RESUMEN

We analyzed volume and diffusivity measures of the corpus callosum (CC) in patients with temporal (TLE) and frontal (FLE) lobe epilepsy in comparison with healthy subjects. On high-resolution T1-weighted scans of 18 controls and 44 patients the volumes (cm(3)) of Witelson regions (WRs) and the entire CC were measured. The apparent diffusion coefficients (ADCs, 10(-5)mm(2)s(-1)) for the entire CC and three areas of interest were measured from co-registered ADC maps. The CC of patients with TLE and FLE, corrected for total brain volume, was smaller than that of controls. Patients' ADC values were higher than those of controls. Findings were significant for WR1, WR2, and WR6, the CC regions connecting the frontal and temporal lobes. Patients with FLE had smaller WR1 and higher ADC values; in patients with TLE, the findings were similar for WR6. Atrophy and increased diffusivity in subregions of the CC connecting homotopic contralateral cortical regions indicate anatomical abnormalities extending beyond the epileptogenic zone in FLE and TLE.


Asunto(s)
Cuerpo Calloso/patología , Imagen de Difusión por Resonancia Magnética , Epilepsia del Lóbulo Frontal/patología , Epilepsia del Lóbulo Temporal/patología , Adulto , Análisis de Varianza , Atrofia , Mapeo Encefálico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadística como Asunto
2.
AJNR Am J Neuroradiol ; 41(2): 238-245, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-32029467

RESUMEN

BACKGROUND AND PURPOSE: Spiral MR imaging has several advantages compared with Cartesian MR imaging that can be leveraged for added clinical value. A multicenter multireader study was designed to compare spiral with standard-of-care Cartesian postcontrast structural brain MR imaging on the basis of relative performance in 10 metrics of image quality, artifact prevalence, and diagnostic benefit. MATERIALS AND METHODS: Seven clinical sites acquired 88 total subjects. For each subject, sites acquired 2 postcontrast MR imaging scans: a spiral 2D T1 spin-echo, and 1 of 4 routine Cartesian 2D T1 spin-echo/TSE scans (fully sampled spin-echo at 3T, 1.5T, partial Fourier, TSE). The spiral acquisition matched the Cartesian scan for scan time, geometry, and contrast. Nine neuroradiologists independently reviewed each subject, with the matching pair of spiral and Cartesian scans compared side-by-side, and scored on 10 image-quality metrics (5-point Likert scale) focused on intracranial assessment. The Wilcoxon signed rank test evaluated relative performance of spiral versus Cartesian, while the Kruskal-Wallis test assessed interprotocol differences. RESULTS: Spiral was superior to Cartesian in 7 of 10 metrics (flow artifact mitigation, SNR, GM/WM contrast, image sharpness, lesion conspicuity, preference for diagnosing abnormal enhancement, and overall intracranial image quality), comparable in 1 of 10 metrics (motion artifacts), and inferior in 2 of 10 metrics (susceptibility artifacts, overall extracranial image quality) related to magnetic susceptibility (P < .05). Interprotocol comparison confirmed relatively higher SNR and GM/WM contrast for partial Fourier and TSE protocol groups, respectively (P < .05). CONCLUSIONS: Spiral 2D T1 spin-echo for routine structural brain MR imaging is feasible in the clinic with conventional scanners and was preferred by neuroradiologists for overall postcontrast intracranial evaluation.


Asunto(s)
Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Neuroimagen/métodos , Adulto , Anciano , Artefactos , Femenino , Humanos , Aumento de la Imagen/métodos , Masculino , Persona de Mediana Edad
3.
AJNR Am J Neuroradiol ; 40(12): 2161-2165, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31624119

RESUMEN

Previous studies have not found structural injury or brain malformations in infants and children with prenatal opioid exposure. As part of an ongoing study evaluating neuroimaging in infants with prenatal opioid exposure, we reviewed structural brain MR imaging in 20 term infants with prenatal opioid exposure and 20 term controls at 4-8 weeks of age. We found that 8 of the 20 opioid-exposed infants had punctate white matter lesions or white matter signal abnormality on structural MR imaging, and 2 of the opioid-exposed infants had a septopreoptic fusion anomaly. No controls had white matter injury or structural malformations. Our findings underscore the importance of clinical neurodevelopmental follow-up and the need for more comprehensive imaging and long-term outcomes research following prenatal opioid exposure.


Asunto(s)
Analgésicos Opioides/efectos adversos , Encéfalo/efectos de los fármacos , Encéfalo/patología , Efectos Tardíos de la Exposición Prenatal/patología , Sustancia Blanca/efectos de los fármacos , Sustancia Blanca/patología , Femenino , Humanos , Lactante , Recién Nacido , Estudios Longitudinales , Imagen por Resonancia Magnética/métodos , Masculino , Neuroimagen/métodos , Embarazo
4.
Cell Biochem Biophys ; 29(1-2): 159-78, 1998.
Artículo en Inglés | MEDLINE | ID: mdl-9631244

RESUMEN

A CHO-K1 cell line stably expressing a recombinant full-length human PDE-IVa (HSPDE4A4B) enzyme was established under hygromycin B selection. Full-length expression of the protein was determined by Western blot analysis, which revealed the presence of a 125-kDa immunoreactive band using rabbit anti-PDE-IVa antibodies. The potency of inhibitor compounds was examined by their ability to increase cAMP in the whole-cell, and by their ability to inhibit cAMP hydrolysis in a 100,000 g supernatant (soluble enzyme preparation) obtained from the same cell line. Inhibition of the expressed PDE-IVa activity by selective PDE-IV inhibitors--(R) and (S)-rolipram, RS 14203, and CDP 840--at 100 nM substrate demonstrated that RS 14203 and CDP 840 were the most potent with IC50 = 9 nM, followed by (R)-rolipram (IC50 = 110 nM) and (S)-rolipram (IC50 = 420 nM). The rank order of potencies of the inhibitors in elevating cAMP in the whole-cell assay was quite different from that on the soluble enzyme. RS 14203 was still the most potent compound in elevating cAMP. Moreover, the relative rank order of potencies between CDP 840 and (R)-rolipram changed dramatically, such that (R)-rolipram was more potent than CDP 840 = (S)-rolipram. An apparent 30-fold stereoselectivity between (R)- and (S)-rolipram was also noted. The whole-cell rank order of potencies was also maintained when PKA activity ratios were measured in place of cAMP levels. The ability of the compounds to elevate cAMP in the stable CHO-K1 cells appeared to track better with the potency of the compounds against the high-affinity (Sr) conformer of the enzyme rather than the low-affinity catalytic state.


Asunto(s)
3',5'-AMP Cíclico Fosfodiesterasas/biosíntesis , 3',5'-AMP Cíclico Fosfodiesterasas/genética , Células CHO/enzimología , Proteínas Recombinantes/biosíntesis , 3',5'-AMP Cíclico Fosfodiesterasas/antagonistas & inhibidores , Animales , Células CHO/química , Catálisis/efectos de los fármacos , Cricetinae , AMP Cíclico/metabolismo , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4 , Activación Enzimática/efectos de los fármacos , Activación Enzimática/genética , Eosinófilos/enzimología , Eosinófilos/metabolismo , Cobayas , Humanos , Hidrólisis/efectos de los fármacos , Inhibidores de Fosfodiesterasa/farmacología , Proteínas Recombinantes/antagonistas & inhibidores , Transfección
5.
Invest Radiol ; 23 Suppl 1: S240-2, 1988 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-3198353

RESUMEN

Under physiologic conditions the stable isotope oxygen-17, in the form of O-17 water, lowers the proton T2 of blood, CSF, tissues, and whole organisms. With MRI the resulting changes in intensity can be detected using spin-echo pulse sequences, but much greater sensitivity is achieved in a fraction of the time with a steady-state free precession sequence such as FISP. With this sequence it is possible to detect levels as low as 0.4% Oxygen-17 water in 53 seconds or less.


Asunto(s)
Medios de Contraste , Imagen por Resonancia Magnética , Isótopos de Oxígeno , Humanos , Técnicas In Vitro , Factores de Tiempo
6.
J Neurosci Methods ; 91(1-2): 55-65, 1999 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-10522824

RESUMEN

While hydrocephalus is common in adults its pathophysiology is not fully understood and its treatment remains problematic. Previous animal models have been acute, developmental, or involved non-specific blockage or inflammation and are not suitable for study of chronic adult-onset hydrocephalus. In this study, we describe the development of a canine model which allows basic physiological studies along with diagnostic and treatment procedures via surgical occlusion of the fourth ventricle with a bolus injection of cyanoacrylic gel glue. A total of 26 adult male canine mongrels were used for the induction of chronic hydrocephalus and were monitored for 1-12 weeks post-induction using magnetic resonance imaging (MRI), intracranial pressure measurements, and neurological fitness assessments. Of these, 81% (21/26) developed hydrocephalus that was mild (N = 6), moderate (N = 7), or severe (N = 8). Pressures were mild and transiently elevated, and brain compliance decreased. Clinical symptoms were also mild and transient. This model is unique in its focal obstruction without local compression or general inflammation and should facilitate the study of the pathophysiology and treatment of chronic adult-onset hydrocephalus.


Asunto(s)
Modelos Animales de Enfermedad , Cuarto Ventrículo/cirugía , Hidrocefalia/fisiopatología , Animales , Encéfalo/patología , Encéfalo/fisiopatología , Cianoacrilatos , Perros , Hidrocefalia/patología , Presión Intracraneal/fisiología , Imagen por Resonancia Magnética , Masculino , Factores de Tiempo
7.
AJNR Am J Neuroradiol ; 18(7): 1339-47, 1997 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-9282867

RESUMEN

PURPOSE: To implement and assess the application of segmented three-dimensional echo-planar MR imaging time-of-flight flow sequences for studying the anatomy of the cervical carotid arteries at 1.5 T. METHODS: The 3-D echo-planar sequences were segmented along the in-plane phase-encoding direction. Echo train lengths (ETLs) of 3 and 5 and signal bandwidths of +/-25, +/-33, and +/-50 KHz were tested along with a conventional (ETL = 1) 3-D MR flow study in six healthy volunteers and in five patients with known arteriosclerotic disease involving the carotid bifurcation as confirmed by conventional angiography. The volunteer data were used to rank the techniques with respect to vessel dimension, vessel/background contrast, and quality by four trained neuroradiologists. For the patient studies, the percentage of stenoses was measured for all MR studies and compared against the conventional angiographic data using the criteria of the North American Symptomatic Carotid Endarterectomy Trial. RESULTS: Using Wilcoxon's test statistic and a significance level of .05, we found that the conventional MR flow examination was better than the segmented techniques and that the segmented techniques with ETL of 3 were superior to their counterparts with ETL of 5. For the ETL of 3 techniques, the high-bandwidth studies were inferior to their lower bandwidth counterparts; however, there was no significant difference between the performance of the medium- and low-bandwidth sequences. The patient data revealed that the segmented techniques consistently overestimated the severity of stenosis; however, in no instance did any of the segmented examinations erroneously indicate the presence of disease. CONCLUSIONS: The reduction in acquisition time and the zero false-positive rate we obtained suggest that segmented 3-D echo-planar MR flow techniques may be used as a screening/locating study for cervical carotid artery disease.


Asunto(s)
Arterias Carótidas/anatomía & histología , Imagen Eco-Planar/instrumentación , Procesamiento de Imagen Asistido por Computador/instrumentación , Angiografía por Resonancia Magnética/instrumentación , Adulto , Anciano , Arteriosclerosis/diagnóstico , Velocidad del Flujo Sanguíneo/fisiología , Enfermedades de las Arterias Carótidas/diagnóstico , Estenosis Carotídea/diagnóstico , Femenino , Humanos , Aumento de la Imagen/instrumentación , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Valores de Referencia
8.
AJNR Am J Neuroradiol ; 14(5): 1215-23, 1993.
Artículo en Inglés | MEDLINE | ID: mdl-8237706

RESUMEN

PURPOSE: To compare conventional T2-weighted spin-echo imaging with a rapid acquisition relaxation enhanced (RARE) technique in the routine evaluation of lumbar degenerative disk disease. METHODS: Thirty consecutive patients referred for evaluation of the lumbar spine for suspected degenerative disk disease were evaluated with sagittal and axial T1-weighted spin-echo, conventional T2-weighted spin-echo, and T2-weighted RARE "turbo spin-echo" sequences (4000/93/2 (repetition time/echo time/excitations), 192 x 256, echo train length of 8). Conventional T2-weighted and RARE images were evaluated independently by two neuroradiologists for image quality, presence of artifacts, cerebrospinal fluid signal intensity, extradural interface conspicuity, intradural nerve root conspicuity, soft-tissue detail, and signal intensity of normal and degenerated intervertebral disks. RESULTS: Both readers rated the cerebrospinal fluid signal higher, the extradural interface conspicuity higher, and the nerve root detail greater on the turbo spin-echo than on conventional spin-echo images. Neither reader had a significant difference in ranking "normal" or "degenerated" disk signal on the two sequences. Both readers rated soft-tissue detail higher for conventional than for turbo spin-echo. CONCLUSION: RARE sequences can replace conventional T2-weighted spin-echo sagittal studies for degenerative lumbar disk disease.


Asunto(s)
Disco Intervertebral , Imagen por Resonancia Magnética/métodos , Enfermedades de la Columna Vertebral/diagnóstico , Artefactos , Humanos , Desplazamiento del Disco Intervertebral/diagnóstico , Estudios Prospectivos , Estenosis Espinal/diagnóstico , Espondilolistesis/diagnóstico
9.
AJNR Am J Neuroradiol ; 15(7): 1351-7, 1994 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-7976949

RESUMEN

PURPOSE: To determine whether fast spin-echo sequences could replace conventional spin-echo methods in the evaluation of head and neck neoplasms and associated adenopathy and to evaluate differences in tissue contrast characteristics between conventional spin-echo and fast spin-echo examinations of head and neck disease. METHODS: Twenty-seven patients with squamous cell carcinoma were imaged on a 1.5-T imager with both conventional spin-echo and fast spin-echo sequences with identical section thickness and position. Twenty-one of the 27 fast spin-echo studies were performed with frequency-selective fat suppression. Three radiologists independently evaluated the images using a five-point scale to compare primary lesion margin definition and conspicuity, lymph node margin definition and conspicuity, gross motion artifact, and flow artifact. Quantitative percent contrast and contrast-to-noise ratios were calculated and compared in 7 cases with fat-suppressed fast spin-echo. RESULTS: Fast spin-echo was preferred by all three readers for lesion margin conspicuity and lymph node conspicuity. Gross motion and flow artifact demonstrated trends toward reader preference for fast spin-echo. Quantitative contrast values for fast spin-echo were significantly greater than those for conventional spin-echo. CONCLUSIONS: Fast spin-echo with fat suppression can replace conventional spin-echo at a time savings of more than 50% and improves tissue contrast and the conspicuity and definition of margins for primary lesions and lymph nodes. Fat-suppression heterogeneity remains the major limitation of this technique. Thus, careful attention to fat-suppression failure and unwanted water saturation is essential.


Asunto(s)
Carcinoma de Células Escamosas/diagnóstico , Neoplasias de Cabeza y Cuello/diagnóstico , Aumento de la Imagen/métodos , Imagen por Resonancia Magnética/métodos , Tejido Adiposo/patología , Artefactos , Carcinoma de Células Escamosas/patología , Neoplasias de Cabeza y Cuello/patología , Humanos , Neoplasias Hipofaríngeas/diagnóstico , Neoplasias Hipofaríngeas/patología , Ganglios Linfáticos/patología , Metástasis Linfática , Neoplasias de la Boca/diagnóstico , Neoplasias de la Boca/patología , Neoplasias Orofaríngeas/diagnóstico , Neoplasias Orofaríngeas/patología
10.
AJNR Am J Neuroradiol ; 13(1): 127-36, 1992.
Artículo en Inglés | MEDLINE | ID: mdl-1595430

RESUMEN

PURPOSE: To assess whether a single enhanced T1-weighted gradient echo volume sequence, with the appropriate reformatted images, could be equivalent to a more conventional 2D set of MR sequences for the evaluation of cervical extradural degenerative disk disease (bony canal and foraminal stenosis; disk herniation). MATERIALS AND METHODS: Sixty-one patients evaluated for extradural degenerative disease by MR were imaged with a "standard" MR examination (Sagittal T1-weighted spin echo, axial low flip angle gradient echo), were then given 0.1 mmol/kg Gd-DTPA intravenously, and reimaged with either a 3D FLASH (fast low angle shot), TR 40/TE 7/1 excitation), 40 degree flip angle, acquired as 64, 2-mm sagittal partitions, or a 3D turbo FLASH (MP RAGE-magnetization prepared rapid acquisition gradient echo) (10/4/1), 10 degree flip angle acquired as 128, 2-mm coronal partitions. The volume sequences were reconstructed in the axial plane, and right and left 45 degree oblique coronal planes. The two sets of examinations (standard vs volume) were prospectively interpreted by two neuroradiologists for quality of examination, and location, type, and severity of extradural degenerative disease in a random, blinded, independent fashion. RESULTS: There was no significant difference between the standard examination and the 3D MP RAGE for central extradural disease. The 3D FLASH examination was significantly worse than the standard examination in identification of central extradural disease, with an average of 21 herniations not identified, or underestimated in size. Neither the 3D FLASH, nor the 3D MP RAGE examinations showed any significant improvement compared to the routine 2D examination for the location and severity of foraminal disease. CONCLUSION: If extradural degenerative disk disease is being evaluated, then a single enhanced 3D T1-weighted imaging sequence taking 6 minutes can be equivalent to a routine set of mixed 2D spin echo and low flip angle gradient echo sequences.


Asunto(s)
Vértebras Cervicales , Medios de Contraste , Gadolinio , Procesamiento de Imagen Asistido por Computador , Disco Intervertebral/patología , Imagen por Resonancia Magnética/métodos , Enfermedades de la Columna Vertebral/diagnóstico , Femenino , Gadolinio DTPA , Humanos , Masculino , Persona de Mediana Edad , Compuestos Organometálicos , Ácido Pentético , Estudios Prospectivos , Enfermedades de la Columna Vertebral/epidemiología
11.
AJNR Am J Neuroradiol ; 11(1): 59-67, 1990.
Artículo en Inglés | MEDLINE | ID: mdl-2105618

RESUMEN

One-hundred-fifteen patients thought to have intracranial disease were studied with various two-dimensional short repetition time, partial-flip-angle gradient-echo techniques: at 1.0 T, fast low-angle short (FLASH) at 10 degrees and 30 degrees and fast imaging with steady-state precession (FISP) at 60 degrees; at 1.5 T, FLASH 10 degrees, 30 degrees, and 60 degrees, FISP 60 degrees, and contrast-enhanced fast steady state at 60 degrees. These sequences were compared with a T2-weighted spin-echo sequence to determine the relative sensitivities of these techniques in detecting parenchymal lesions. Except for hemorrhagic lesions a substantial number of abnormalities were either not visible or poorly seen on the partial-flip-angle gradient-echo sequences. Minimizing echo time (6-9 msec) to decrease magnetic susceptibility effects did not improve lesion detection. Current usage of two-dimensional gradient-echo techniques for lesion detection is limited, except when calcification or hemorrhage is involved. Their utility may be expanded via the incorporation of three-dimensional techniques and IV contrast agents.


Asunto(s)
Encefalopatías/diagnóstico , Encefalopatías/patología , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/patología , Humanos , Imagen por Resonancia Magnética/métodos
12.
AJNR Am J Neuroradiol ; 20(10): 1863-70, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10588110

RESUMEN

BACKGROUND AND PURPOSE: The treatment algorithm for acute cerebrovascular accidents has traditionally sorted these accidents as either hemorrhagic or nonhemorrhagic, and MR imaging, with its ability to allow expeditious assessment of vascular substrates and regional blood volume, is well suited for this purpose. Our purpose was to delineate the accuracy of MR imaging in acute, hemorrhagic forms of stroke during the time frame considered beneficial for intervention in an animal model. METHODS: Eighteen dogs with small, iatrogenic parenchymal, subarachnoid hemorrhage (SAH), or both were serially scanned over the initial 6-hour postictal period. Confirmatory pathologic specimens and 3-hour postictal CT scans were obtained in all animals. The MR and CT studies were then interpreted in a blinded fashion by two neuroradiologists for the presence of hemorrhage. The results were subjected to receiver operating characteristic analysis. RESULTS: MR imaging depicted acute parenchymal hemorrhage and SAH with a high degree of accuracy at 1.5 T. This finding was independent of each of the time points studied during the 6-hour window. For SAH, the MR accuracy for reader 1 was 0.86 (95% CI, 0.76-0.97); for reader 2, accuracy was 0.85 (95% CI, 0.71-0.99). The CT accuracy for the two readers was 0.42 (95% CI, 0.26-0.58) and 0.66 95% CI, 0.43-0.89), respectively. Fluid-attenuated inversion-recovery images improved the conspicuity of SAH on MR images and, along with spin-density-weighted spin-echo sequences, helped to establish the hemorrhagic nature. For parenchymal hemorrhage, the MR accuracy for reader 1 was 0.90 (95% CI, 0.81-0.99); for reader 2, accuracy was 0.93 (95% CI, 0.84-1.00). With CT, the accuracy of reader 1 was 0.91 (95% CI, 0.85-0.97) whereas for reader 2 accuracy was 0.76 (95% CI, 0.69-.83). Parenchymal hemorrhage detection and diagnosis was best with T2*-weighted gradient-echo images. CONCLUSION: MR imaging with appropriately selected sequences appears able to provide information regarding the presence (or absence) of hemorrhage in an acute stroke model requisite to the initiation of treatment.


Asunto(s)
Hemorragia Cerebral/diagnóstico , Aumento de la Imagen , Imagen por Resonancia Magnética , Hemorragia Subaracnoidea/diagnóstico , Enfermedad Aguda , Animales , Encéfalo/patología , Modelos Animales de Enfermedad , Perros , Curva ROC , Sensibilidad y Especificidad
13.
Top Magn Reson Imaging ; 3(3): 1-11, 1991 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-2054194

RESUMEN

The basic process of MRI consists of two essential, relatively independent components: (1) excitation in the form of a radiofrequency pulse sequence, and (2) signal sampling and localization, that is, forming the MR image through the use of field gradients. The presence of motion (blood flow) during either excitation or sampling results in two types of corresponding effects: (1) time-of-flight effects, and (2) spin phase phenomena. These effects can be manipulated through the use of special coils, pulse sequences, gradients, and postprocessing techniques to provide angiographic images in which simple motion provides the basis for contrast.


Asunto(s)
Angiografía Cerebral/métodos , Imagen por Resonancia Magnética/métodos , Humanos , Magnetismo
14.
Top Magn Reson Imaging ; 2(2): 31-48, 1990 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-2184857

RESUMEN

The pursuit of capabilities for the evaluation of functional aspects of cardiovascular disease by MRI has resulted in the development and implementation of a number of interesting techniques that can be performed on a conventional scanner. Some currently available techniques emphasize the production of anatomically accurate images representing different phases of the cardiac cycle; others demonstrate physical changes within the acquired data that reflect motion, such as blood flow. Magnitude data from spin-echo and gradient-echo sequences can be used to produce dynamic images of the cardiovascular system. Phase data can be used to generate flow-based images reflecting the movement of blood protons. These techniques can be applied in the evaluation of ventricular function, valve function, or functional abnormalities in either congenital cardiovascular disease or great artery disease.


Asunto(s)
Enfermedades Cardiovasculares/diagnóstico , Sistema Cardiovascular/fisiopatología , Imagen por Resonancia Magnética , Enfermedades Cardiovasculares/patología , Enfermedades Cardiovasculares/fisiopatología , Sistema Cardiovascular/patología , Electrocardiografía , Cardiopatías Congénitas/diagnóstico , Humanos , Interpretación de Imagen Asistida por Computador , Imagen por Resonancia Magnética/métodos , Contracción Miocárdica
15.
Magn Reson Imaging ; 6(4): 373-89, 1988.
Artículo en Inglés | MEDLINE | ID: mdl-3185131

RESUMEN

Optimal angle, fast repeat time, gradient field echo imaging techniques such as FISP (Fast Imaging with Steady Precession) and FLASH (Fast Low Angle Shot) often fail to discriminate disease from healthy tissue for two main reasons. First, T1 and T2 of the affected tissue may increase such that the ratio of T1 to T2 remains nearly unchanged, hence there is no contrast change with FISP. Second, T2 weighted gradient field echo images suffer severely from T2* signal and resolution loss leading to a reduction in C/N. Although FLASH imaging with two separate angles can, in principle, extract the longer T1 tumors, contrast is often not good. To overcome the inhomogeneity and contrast problems, we have implemented a FAst optimal angle spin-echo sequence with a short TE(FATE). For the first echo, FATE has the same contrast properties as FLASH with a slight decrease in signal intensity. The advantage is that the intensity of the signal does not suffer from T2* signal decay, hence improved contrast and disease detection via T2 weighted FATE images is possible. Contrast-to-noise in lesion detection is also considered for CE FAST (Contrast Enhanced Fast), a T2-weighted version of FISP, and HYBRID.


Asunto(s)
Imagen por Resonancia Magnética/métodos , Encéfalo/anatomía & histología , Encefalopatías/diagnóstico , Humanos , Aumento de la Imagen , Espectroscopía de Resonancia Magnética , Matemática , Modelos Estructurales , Factores de Tiempo
16.
Dermatol Clin ; 7(1): 1-18, 1989 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-2646041

RESUMEN

The author discusses methods of developing alternative therapies when standard treatments have proved ineffective or do not exist. Specific treatments for a wide range of stubborn or difficult dermatologic conditions are presented.


Asunto(s)
Terapias Complementarias , Enfermedades de la Piel/terapia , Terapia Asistida por Computador , Humanos
17.
Dermatol Clin ; 7(1): 63-9, 1989 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-2646050

RESUMEN

This article is a tribute to clinician Henry M. Lewis. The author shares practical therapeutic pearls developed and used over the years by Dr. Lewis.


Asunto(s)
Enfermedades de la Piel/historia , Historia del Siglo XX , Humanos , Enfermedades de la Piel/terapia , Estados Unidos
18.
Acta Neurochir Suppl ; 87: 141-5, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-14518542

RESUMEN

INTRODUCTION: While it is desirable to perform MRI examinations in patients with deep brain stimulators (DBS), a major safety concern exists regarding the potential for excessive heating secondary to magnetically induced electrical currents. This study was designed to determine the safety of MRI and DBS. METHODS: Standard configurations of DBS systems were tested. In vitro testing was performed using a 1.5-Tesla MR system, a gel-filled phantom, and the body and head RF coils with varying levels of RF energy (SAR). A fluoroptic thermometry system was used to record temperatures. RESULTS: Using the 1.5-T MRI and body RF transmit coil, the temperature changes ranged from 2.5 to 25.3 degrees C. Using the 1.5-T MRI and head RF transmit coil, the temperature changes ranged from 2.3 to 7.1 degrees C. CONCLUSIONS: Excessive heating does occur with certain MR imaging conditions. Under certain conditions determined in this study, patients with DBS may safely undergo anatomical MR imaging. In the future, standardized testing and more comprehensive studies will be needed to ensure the MR safety of neurostimulation systems.


Asunto(s)
Lesiones Encefálicas/etiología , Quemaduras/etiología , Terapia por Estimulación Eléctrica/efectos adversos , Electrodos Implantados/efectos adversos , Campos Electromagnéticos , Seguridad de Equipos/métodos , Imagen por Resonancia Magnética/efectos adversos , Temperatura Corporal/efectos de la radiación , Lesiones Encefálicas/prevención & control , Quemaduras/prevención & control , Análisis de Falla de Equipo , Calor/efectos adversos , Humanos , Fantasmas de Imagen , Radiometría/métodos , Termografía
19.
Cutis ; 29(2): 187-8, 1982 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-6460597

RESUMEN

After four months of use, a 13-year-old girl with acne developed allergic contact urticaria to 5 percent topical benzoyl peroxide. This was confirmed by closed patch tests. It is suggested that concomitant use of an abrasive scrub cleanser may have damaged the stratum corneum and initiated or enhanced sensitization.


Asunto(s)
Peróxido de Benzoílo/efectos adversos , Peróxidos/efectos adversos , Urticaria/inducido químicamente , Acné Vulgar/tratamiento farmacológico , Adolescente , Peróxido de Benzoílo/inmunología , Dermatitis por Contacto , Femenino , Humanos , Urticaria/inmunología
20.
Cutis ; 28(4): 454, 463, 1981 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-7307567

RESUMEN

A 30-year-old woman with aquagenic urticaria developed hives every time she came in contact with a water source such as tap water, snow or sweat. The patient's condition was satisfactorily controlled with cyproheptadine hydrochloride. I believe the triggering event in these attacks may have been an osmotic stimulus.


Asunto(s)
Urticaria/etiología , Agua , Adulto , Ciproheptadina/uso terapéutico , Femenino , Humanos , Presión Osmótica , Urticaria/tratamiento farmacológico
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