RESUMEN
OBJECTIVE: The aim of this study was to establish whether abnormal signal intensity in the posterior limb of the internal capsule (PLIC) on magnetic resonance imaging is an accurate predictor of neurodevelopmental outcome at 1 year of age in infants with hypoxic-ischemic encephalopathy (HIE). METHODS: We have examined 73 term neonates with HIE between 1 and 17 days after birth with cranial magnetic resonance imaging and related the magnetic resonance imaging findings to neurodevelopmental outcome at 1 year of age. RESULTS: All infants with an abnormal signal intensity in the PLIC developed neurodevelopmental impairment although in 4 infants with very early scans the abnormal signal was not apparent until up to 4 days after birth. A normal signal intensity was associated with a normal outcome in all but 4 cases; 3 of these infants had minor impairments and all had persistent imaging changes within the white matter. The 4th infant with a normal signal intensity on day 2 died before a further image could be obtained. The absence of normal signal predicted abnormal outcome in term infants with HIE with a sensitivity of 0.90, a specificity of 1.0, a positive predictive value of 1.0, and a negative predictive value of 0.87. The test correctly predicted outcome in 93% of infants with grade II HIE, according to the Sarnat system. Applying a Bayesian approach, the predictive probability of the test (the probability that the test would predict an outcome correctly) was distributed with a mean of 0.94 and 95% confidence limits of 0.89 to 1.0. CONCLUSION: Abnormal signal intensity in the PLIC is an accurate predictor of neurodevelopmental outcome in term infants suffering HIE.
Asunto(s)
Daño Encefálico Crónico/diagnóstico , Isquemia Encefálica/diagnóstico , Encéfalo/patología , Discapacidades del Desarrollo/diagnóstico , Hipoxia Encefálica/diagnóstico , Imagen por Resonancia Magnética , Ganglios Basales/patología , Corteza Cerebral/patología , Dominancia Cerebral/fisiología , Femenino , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Masculino , Examen Neurológico , Sensibilidad y Especificidad , Tálamo/patologíaRESUMEN
PURPOSE: To compare conventional two-dimensional multisection images with registered three-dimensional volume and subtraction images for detecting subtle changes in the brains of infants and children. METHODS: Twenty-six patients (24 with hemorrhagic/ischemic lesions) and one each with perinatal infection and Sturge-Weber disease were examined on two or more occasions with conventional multisection T1- and T2-weighted sequences as well as with 3-D T1-weighted volume sequences. A registration program was used to match the volume images to subvoxel dimensions, and subtracted images (second volume set minus the first) were obtained. The multisection images were compared with the 3-D and subtracted images and graded for detection of changes in a variety of brain structures. RESULTS: In 16% to 33% of comparisons of different structures, the multisection images and the 3-D registered and subtracted images showed changes equally well. The 3-D registered and subtracted images were better than the multisection images in 67% to 84% of comparisons for detection of changes in the cerebral hemispheres, ventricles, brain stem, cerebellum, and in lesions. Statistically significant differences were found between the graded performance of the registered 3-D images and the conventional 2-D images in detecting cerebral infarction and hypoxic ischemic encephalopathy. In the late phase following neonatal cerebral infarction (1 to 11 months), the 3-D registered and subtracted images revealed growth of the brain at the margins of the lesions. CONCLUSION: Subvoxel registration of serial MR images may be of value in detecting subtle changes in the brains of infants and children.
Asunto(s)
Encefalopatías/diagnóstico , Encéfalo/patología , Recien Nacido Prematuro , Imagen por Resonancia Magnética/métodos , Encéfalo/anatomía & histología , Niño , Preescolar , Diagnóstico Diferencial , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Variaciones Dependientes del Observador , Sensibilidad y EspecificidadRESUMEN
We have used registered serial magnetic resonance scans to assess the growth of the brain after perinatal infarction in six infants. The initial scans were performed at ages of 4 days to 8 weeks and follow-up studies were performed from 4 days to 21 weeks later. A three-dimensional volume acquisition was performed on each occasion. Rigid body translations and rotations were used to match the images obtained on each occasion. Subtraction of the first image from the second then provided an assessment of the growth of the brain that had occurred between the two examinations. In the early phase of infarction (up to 2 months) low signal areas with clearly defined margins developed at the site of infarction. In the late phase (2 months onwards) growth was seen in the brain at the margins of the infarct in each case, and the size of the infarcted region showed a marked decrease in size. The rate of growth of the brain into the infarcted area exceeded that of the surrounding brain in some cases and was less in others. Growth of undamaged tissue may provide an important mechanism for recovery of the developing brain.
Asunto(s)
Infarto Cerebral/fisiopatología , Regeneración Nerviosa/fisiología , Encéfalo/patología , Encéfalo/fisiopatología , Infarto Cerebral/diagnóstico , Femenino , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Examen NeurológicoRESUMEN
Eighteen term infants with hypoxic ischaemic encephalopathy (HIE) were studied with serial magnetic resonance imaging of the brain for up to two months following birth. Important early findings included brain swelling, cortical highlighting, diffuse loss of grey/white differentiation and loss of signal in the posterior limb of the internal capsule (PLIC). These signs were easier to identify on T1-weighted spin echo or inversion recovery sequences than on T2-weighted spin echo sequences. Brain swelling was only seen in the first seven days and was present in all grades of HIE. All other signs persisted and were associated with the subsequent development of major structural changes in the brain. The exact pattern of injury was best identified after the first week of life once the signs of brain swelling had cleared.
Asunto(s)
Isquemia Encefálica/complicaciones , Isquemia Encefálica/fisiopatología , Lóbulo Frontal/fisiopatología , Hipoxia/complicaciones , Hipoxia/fisiopatología , Lóbulo Occipital/fisiopatología , Asfixia Neonatal/etiología , Asfixia Neonatal/fisiopatología , Ganglios Basales/fisiopatología , Ventrículos Cerebrales/anomalías , Hipocampo/fisiopatología , Humanos , Recién Nacido , Imagen por Resonancia Magnética , Índice de Severidad de la Enfermedad , Tálamo/fisiopatologíaRESUMEN
Twenty-two neonates (11 term and 11 preterm) with predominantly unilateral hemispheric lesions on ultrasound were re-examined clinically and by magnetic resonance imaging (MRI) at between two and nine years of age. The aim was to correlate early ultrasound and late MRI findings with the development of hemiplegia. At follow-up, five children were normal and 15 had hemiplegia, which was mild in seven and moderate in 10. The presence or absence of hemiplegia, or its severity, could not be predicted from either early ultrasound or later MRI appearances.
Asunto(s)
Encefalopatías/diagnóstico , Hemiplejía/congénito , Hemiplejía/patología , Recien Nacido Prematuro , Encefalopatías/complicaciones , Niño , Preescolar , Hemiplejía/diagnóstico por imagen , Humanos , Recién Nacido , Imagen por Resonancia Magnética , Estudios Prospectivos , Tomografía Computarizada por Rayos X , UltrasonografíaRESUMEN
The visual function of 42 children with haemorrhagic and/or ischaemic cerebral lesions acquired before a gestational age of 35 weeks was examined and related to cranial ultrasound in the neonatal period and to MRI and neurodevelopmental status at follow-up. All 37 children with abnormal ultrasound scans and one of the five with normal ultrasound scans showed impairment of one or more aspects of visual function. While impaired acuity was more frequent among infants with MRI evidence of visual pathway damage, this was not an invariable finding. Normal or near-normal visual acuity did not preclude the presence of other functional visual deficits. The authors conclude that preterm cerebral insults may produce a variety of visual difficulties, the pattern and severity of which cannot be predicted on imaging. Each child therefore requires individual assessment of multiple aspects of visual function.
Asunto(s)
Trastornos Cerebrovasculares/diagnóstico , Recien Nacido Prematuro/fisiología , Trastornos de la Visión/fisiopatología , Visión Ocular/fisiología , Encéfalo/patología , Encéfalo/fisiopatología , Trastornos Cerebrovasculares/complicaciones , Trastornos Cerebrovasculares/fisiopatología , Niño , Preescolar , Ecoencefalografía , Potenciales Evocados Visuales/fisiología , Femenino , Edad Gestacional , Humanos , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Valor Predictivo de las Pruebas , Trastornos de la Visión/etiologíaRESUMEN
Forty term infants with hypoxic-ischaemic encephalopathy were assessed during the neonatal period with cranial ultrasound and MRI, and the findings were compared with outcome at one year of age. 38 had abnormalities on ultrasound and all had changes on MRI. The incidence of changes in the basal banglia/thalami and periventricular white matter was much greater with MRI than with ultrasound. Changes in the basal ganglia and thalami on MRI were associated with a poor outcome if they had also been detected with ultrasound. However, MRI identified four small infarcts which were not detected by ultrasound. There was no consistent association between periventricular white matter change on MRI and outcome. Regular ultrasound scanning identified all infants with a poor outcome. A normal ultrasound or isolated findings of intraventricular haemorrhage, subarachnoid haemorrhage or transient flares were associated with a normal outcome in 13 of 14 infants.
Asunto(s)
Isquemia Encefálica/diagnóstico , Hemorragia Cerebral/diagnóstico , Ecoencefalografía , Hipoxia Encefálica/diagnóstico , Imagen por Resonancia Magnética , Isquemia Encefálica/diagnóstico por imagen , Isquemia Encefálica/etiología , Hemorragia Cerebral/complicaciones , Hemorragia Cerebral/diagnóstico por imagen , Humanos , Hipoxia Encefálica/diagnóstico por imagen , Hipoxia Encefálica/etiología , Lactante , Recién NacidoRESUMEN
Twelve newborn infants with clinical evidence of hypoxic ischemic brain injury had conventional and diffusion-weighted magnetic resonance imaging (MRI) performed one to six (median two) days and 7-42 days after birth. The extent and conspicuity of the early abnormalities was greater with diffusion-weighted than with conventional imaging in each of the four infants with neonatal infarction and in four of the infants with Grades II or III hypoxic ischemic encephalopathy (HIE). No abnormality was seen with either technique in the other four infants who had Grades I or II HIE. Diffusion weighted MRI may be important for the early diagnosis and grading of infants with hypoxic ischemic brain injury.
Asunto(s)
Asfixia Neonatal/diagnóstico , Daño Encefálico Crónico/diagnóstico , Infarto Cerebral/diagnóstico , Hipoxia Encefálica/diagnóstico , Imagen por Resonancia Magnética/métodos , Agua Corporal/metabolismo , Encéfalo/patología , Corteza Cerebral/patología , Difusión , Estudios de Seguimiento , Humanos , Recién NacidoRESUMEN
Neonates with unilateral hemispheric lesions detected by imaging in the newborn period are at risk for developing hemiplegia. Five full-term infants with predominantly unilateral lesions identified by cranial ultrasound in the neonatal period and confirmed with MRI were examined clinically at regular intervals in order to establish the development, incidence and evolution of later hemiplegia and the evolution of hemiplegic signs. In the neonatal period the infants had either a normal examination or subtle transient abnormalities. Abnormalities were not seen until 6 months of age in infants who developed hemiplegia. The number of hemiplegic signs in each child increased with time, the earlier the signs appeared the more severe the hemiplegia. In some infants deterioration with loss of preexisting skills was observed. At 24 months two of the infants were normal, one had a mild and two a moderate hemiplegia.
Asunto(s)
Daño Encefálico Crónico/diagnóstico , Dominancia Cerebral/fisiología , Hemiplejía/diagnóstico , Corteza Cerebral/patología , Infarto Cerebral/diagnóstico , Parálisis Cerebral/diagnóstico , Ecoencefalografía , Femenino , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Examen Neurológico , Estudios ProspectivosRESUMEN
The degree of Wallerian degeneration (WD) in the corticospinal tracts seen with magnetic resonance imaging (MRI) was correlated with the distribution and severity of congenital hemiplegia in 20 children aged nine months to nine years. All the children had hemispheric lesions diagnosed with ultrasound in the neonatal period: MRI and clinical assessment were performed from nine months to nine years of age. Hemiplegia was graded as mild, moderate or severe and into predominantly upper or lower limb distribution. WD was assessed by the presence or absence of signal intensity changes in the internal capsule on inversion recovery and spin echo sequences and by the asymmetry of the upper brainstem. The degree of asymmetry was estimated by measuring the cross sectional area (CSA) of the brainstem at three levels and calculating the ratio of the measurements between the side of the lesion and the unaffected side. Infarct size was estimated from the CSA of the infarct at the maximum site of the lesion. Both measurements were correlated with the severity of outcome and the site of involvement. There was a better correlation between severity of outcome and brainstem asymmetry (p = 0.003) than severity of outcome and infarct size (p = 0.02). There was also a significant correlation between upper limb involvement and brainstem asymmetry (p = 0.01). As WD estimated by brainstem asymmetry appears early and is easy to measure, it may be a good marker to estimate later impairment in infants with predominantly unilateral hemispheric haemorrhagic/ischaemic lesions diagnosed in the neonatal period.
Asunto(s)
Hemiplejía/congénito , Hemiplejía/diagnóstico , Tronco Encefálico/patología , Infarto Cerebral/complicaciones , Infarto Cerebral/diagnóstico , Niño , Preescolar , Femenino , Hemiplejía/etiología , Humanos , Lactante , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Valor Predictivo de las Pruebas , Pronóstico , Tractos Piramidales/patología , Índice de Severidad de la Enfermedad , Degeneración WallerianaRESUMEN
A 3-4% change in signal intensity correlated with visual stimulation was observed in the occipital lobes of three normal volunteers examined with MRI at 0.15 T using fluid attenuated inversion recovery pulse sequences. Similar results were observed at 1.0 T. A double difference technique in which difference images are themselves opposed provided an increase in sensitivity.
Asunto(s)
Encéfalo/fisiología , Imagen por Resonancia Magnética , Encéfalo/anatomía & histología , Humanos , Persona de Mediana Edad , Estimulación LuminosaRESUMEN
T2-weighted spin echo scans were performed on a neonate and two adults aged 42 and 60 years within 2 weeks of the onset of infarction in the frontoparietal region of the brain. Areas of increased signal intensity were observed in the anterior and posterior limbs of the internal capsule in the infant and in the posterior limbs of the internal capsules in the adults. Although these signal changes were typical of the chronic phase of Wallerian degeneration, their onset was much earlier than the 10-14 weeks previously described for this stage in adults. The low level of myelination of white matter tracts at birth, and the relatively sparse myelination of the parietopontine tract may account for the rapid onset of changes in these patients which more closely follows the time course described pathologically for Wallerian degeneration in unmyelinated fibres.
Asunto(s)
Encéfalo/patología , Imagen por Resonancia Magnética , Degeneración Walleriana , Adulto , Isquemia Encefálica/diagnóstico , Femenino , Lóbulo Frontal/irrigación sanguínea , Lóbulo Frontal/patología , Humanos , Recién Nacido , Masculino , Persona de Mediana Edad , Fibras Nerviosas Mielínicas/patología , Lóbulo Parietal/irrigación sanguínea , Lóbulo Parietal/patologíaRESUMEN
Magnetic resonance imaging examination of the upper spinal cord was done in sixteen adult patients with clinically definite multiple sclerosis (MS) by T2 weighted fluid attenuated inversion recovery (FLAIR) scanning in which the signal from cerebrospinal fluid was suppressed. These scans were compared with matched images obtained with conventional T1 and T2 weighted pulse sequences (including contrast enhancement). 6 lesions (five patients) were seen with the conventional scans and 37 lesions (fourteen patients) were seen with the FLAIR scans. The FLAIR sequence considerably improves the ability of MRI to demonstrate spinal involvement in MS.
Asunto(s)
Aumento de la Imagen/métodos , Imagen por Resonancia Magnética/métodos , Esclerosis Múltiple/diagnóstico , Enfermedades de la Columna Vertebral/diagnóstico , Adulto , Artefactos , Líquido Cefalorraquídeo , Estudios de Evaluación como Asunto , Femenino , Humanos , Aumento de la Imagen/normas , Imagen por Resonancia Magnética/normas , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/líquido cefalorraquídeo , Esclerosis Múltiple/epidemiología , Sensibilidad y Especificidad , Enfermedades de la Columna Vertebral/líquido cefalorraquídeo , Enfermedades de la Columna Vertebral/epidemiologíaRESUMEN
Heavily T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences with inversion times of 2000-2500 ms and echo times of 130-200 ms were used to image the brain stem of a normal adult and five patients. These sequences produce high signal from many white matter tracts and display high lesion contrast. The corticospinal and parietopontine tracts, lateral and medial lemnisci, superior and inferior cerebellar peduncles, medial longitudinal fasciculi, thalamo-olivary tracts and the cuneate and gracile fasciculi gave high signal and were directly visualised. The oculomotor and trigeminal nerves were demonstrated within the brain stem. Lesions not seen with conventional T2-weighted spin echo sequences were seen with high contrast in patients with infarction, multiple sclerosis, sarcoidosis, shunt obstruction and metastatic tumour. The anatomical detail and high lesion contrast given by the FLAIR pulse sequence appear likely to be of value in diagnosis of disease in the brain stem.
Asunto(s)
Neoplasias Encefálicas/secundario , Tronco Encefálico/patología , Infarto Cerebral/diagnóstico , Medios de Contraste , Imagen por Resonancia Magnética/métodos , Esclerosis Múltiple/diagnóstico , Adulto , Encefalopatías/diagnóstico , Neoplasias Encefálicas/diagnóstico , Derivaciones del Líquido Cefalorraquídeo , Combinación de Medicamentos , Femenino , Gadolinio DTPA , Humanos , Hidrocefalia/diagnóstico , Neoplasias Pulmonares/diagnóstico , Meglumina , Persona de Mediana Edad , Compuestos Organometálicos , Ácido Pentético , Complicaciones Posoperatorias/diagnóstico , Sarcoidosis/diagnósticoRESUMEN
Fluid attenuated inversion recovery pulse sequences with a long echo time (TE) have been used to image the brain in one volunteer and four patients. The long inversion time used with this sequence suppresses the signal from CSF and the long TE produces very heavy T2 weighting. The marked reduction in flow artefact from CSF and the high T2 weighting enabled anatomical detail to be seen within the brain stem and produced high lesion contrast in areas close to CSF. Lesions were demonstrated with greater conspicuity than with conventional T2-weighted sequences in patients with cerebral infarction, low grade astrocytoma, and diplegia.
Asunto(s)
Encefalopatías/patología , Encéfalo/patología , Imagen por Resonancia Magnética/métodos , Adolescente , Adulto , Anemia de Células Falciformes/patología , Astrocitoma/patología , Isquemia Encefálica/patología , Neoplasias Encefálicas/patología , Arteria Carótida Interna/patología , Estenosis Carotídea/patología , Infarto Cerebral/patología , Niño , Cuerpo Calloso/patología , Femenino , Humanos , Hipoxia Encefálica/patología , Parálisis/patologíaRESUMEN
PURPOSE: Results from conventional T2-weighted spin-echo sequences were compared with those obtained using fluid attenuated inversion recovery (FLAIR) pulse sequences in order to assess their relative merits in detecting disease. METHODS: Forty adult patients with suspected disease of the brain were examined with spin-echo sequences (TE = 20 and TE = 80), and results were compared with FLAIR sequences of several types with inversion times of 1800-3000 msec and echo times of 130-240 msec. Scans were assessed by two radiologists for lesion number, conspicuity, and extent. RESULTS: A total of 48 lesions or groups of lesions were recognized with both sequences. In 22 instances, more lesions were seen with FLAIR sequences, and, in the remaining 26, equal numbers were seen. In 42 lesions, conspicuity was better with FLAIR sequences, equal in five and worse in one cystic lesion. Lesion extent was better assessed in 28 of the 48 cases with FLAIR sequences and equally well seen in the remainder. CONCLUSION: By virtue of their long echo time and relative freedom from cerebrospinal fluid artifact FLAIR sequences provide high sensitivity to a wide range of disease. The basic sequence is easy to implement but is relatively time consuming.
Asunto(s)
Encefalopatías/diagnóstico , Neoplasias Encefálicas/diagnóstico , Adulto , Neoplasias Encefálicas/secundario , Infarto Cerebral/diagnóstico , Trastornos Cerebrovasculares/diagnóstico , Infecciones por Citomegalovirus/diagnóstico , Humanos , Imagen por Resonancia Magnética/métodos , Persona de Mediana Edad , Esclerosis Múltiple/diagnósticoRESUMEN
Three cases of athetoid cerebral palsy after hypoxic-ischaemic encephalopathy (HIE) are reported. All three neonates had haemorrhagic lesions in the basal ganglia and thalami on magnetic resonance imaging (MRI). Prior cranial ultrasound had detected the lesions in only two cases. In all three children athetoid movements began within the first year of life. Follow up MRI scans showed bilateral symmetrical cystic lesions in the posterior putamen. Although haemorrhagic lesions within the basal ganglia are a common MRI finding in neonates with HIE, few of these babies develop athetoid cerebral palsy. We believe this to be the first report of discrete cystic lesions found in the basal ganglia of children with athetoid cerebral palsy.
Asunto(s)
Enfermedades de los Ganglios Basales/etiología , Isquemia Encefálica/complicaciones , Parálisis Cerebral/etiología , Quistes/etiología , Hipoxia Encefálica/complicaciones , Putamen , Enfermedades de los Ganglios Basales/diagnóstico , Enfermedades de los Ganglios Basales/epidemiología , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/epidemiología , Parálisis Cerebral/diagnóstico , Parálisis Cerebral/epidemiología , Quistes/diagnóstico , Quistes/epidemiología , Ecoencefalografía , Femenino , Humanos , Hipoxia Encefálica/diagnóstico , Hipoxia Encefálica/epidemiología , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Estudios Prospectivos , Putamen/diagnóstico por imagen , Putamen/patología , Enfermedades Talámicas/diagnóstico , Enfermedades Talámicas/epidemiología , Enfermedades Talámicas/etiología , Tomografía Computarizada por Rayos XRESUMEN
Inversion recovery (IR) sequences with an inversion time (TI) designed to markedly reduce or null the signal from CSF (TI of approximately 2,100 ms at 1.0 T) and a very long echo time (TE) of 240 ms were used to image the brain of two normal adult volunteers, one 34-year-old man with an intrinsic tumor, and one 3-month-old infant with an infarct. Using these very heavily T2-weighted pulse sequences, adult gray and white matter showed similar signal intensity in many areas of the brain, but normal white matter in regions of the centrum semiovale, posterior internal capsule, parietopontile tract, occipitothalamic radiation, and brain stem showed a much higher signal intensity than surrounding gray or white matter. The infant displayed a low signal intensity in myelinated regions in the internal capsule and occipitothalamic radiation and a high signal in unmyelinated white matter. In many of the images there were strong similarities to the distribution of high signal within white matter seen with pulsed gradient spin echo sequences (TE 130 ms) designed to demonstrate effects due to anisotropic diffusion. Arguments are advanced to support the view that the high signal intensity in white matter tracts is due to one or more long T2 components that may be associated with unmyelinated or sparsely myelinated fibres within white matter. The resemblance to diffusion weighted images may reflect the fact that both employ long TEs and both produce a low signal from CSF. If myelin possessed a different susceptibility from axoplasm so that magnetic field gradients were generated around nerve fibres when their orientation was not parallel to B0, diffusion of water might then produce the observed dependence on fibre direction. The high signal regions in white matter are a potential source of confusion in image interpretation, and measurements of T2 in white matter need to be made with these regional variations in mind. The concept of normal appearing white matter also needs to be applied with a knowledge of these differences. The IR sequences used in this study provide a very high T2 dependence with a low signal from CSF and may be useful for detecting disease in the CNS of adults and children.
Asunto(s)
Encéfalo/anatomía & histología , Imagen por Resonancia Magnética , Adulto , Encéfalo/patología , Neoplasias Encefálicas/diagnóstico , Infarto Cerebral/diagnóstico , Humanos , Lactante , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana EdadRESUMEN
Brain MR examinations were performed on one normal and 30 abnormal neonates and infants with a variety of clinical problems using pulsed gradient spin echo (PGSE) sequences sensitized in different directions to detect changes due to anisotropically restricted diffusion of water within the brain. Anisotropically restricted diffusion was demonstrated within white matter, which appeared to be myelinated with T1-weighted inversion recovery or spin echo sequences and within white matter where the presence of myelin was not demonstrated with these sequences. Cysts and fluid collections were recognised by their low signal intensity using PGSE sequences in the subcortical regions, lentiform nuclei, and periventricular regions. An intracerebral hematoma and a subdural hematoma showed a high signal intensity with PGSE sequences consistent with isotropically restricted diffusion. Chronic infarction displayed a low signal intensity consistent with relatively free isotropic diffusion. Patients with leukodystrophy associated with congenital muscular dystrophy showed an anisotropic pattern with different components of the abnormality present on images with sensitization in different directions. The corticospinal tracts failed to show highlighting in three cases where conventional imaging was normal. In several patients with a history of birth asphyxia, asymmetry and a relative reduction in signal intensity were seen in the corticospinal tracts.
Asunto(s)
Encefalopatías/diagnóstico , Encéfalo/anatomía & histología , Imagen por Resonancia Magnética , Asfixia Neonatal/diagnóstico , Agua Corporal/metabolismo , Encéfalo/anomalías , Encéfalo/patología , Isquemia Encefálica/diagnóstico , Cuerpo Calloso/patología , Difusión , Femenino , Hematoma/diagnóstico , Hematoma/diagnóstico por imagen , Humanos , Lactante , Recién Nacido , Masculino , Distrofias Musculares/diagnóstico , Tractos Piramidales/anatomía & histología , Valores de Referencia , Sensibilidad y Especificidad , UltrasonografíaRESUMEN
Soluble and insoluble polysaccharides were derivatized with diethylenetriaminepentaacetic acid (DTPA) and/or spin-labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Polysaccharides derivatized with DTPA were prepared via cyanogen bromide activation, coupling to a diamine linker, and to DTPA anhydride. Spin-labeled polysaccharides were also prepared via cyanogen bromide activation. The extent of derivatization for dextran (18 kDa) was about 120 glucose units per DTPA, and for cellulose and starch about 15-30 units per DTPA. For spin-labeled polysaccharides, the average loading ranged from 1 nitroxide per 16 glucose units for starch to 181 for dextran (82 kDa). These derivatized paramagnetic polysaccharides were shown to be more effective relaxants than the small paramagnetic molecules alone. Both soluble and insoluble polysaccharide-linker-DTPA-Gd(III) complexes were effectively cleared from the body (rats) after oral administration. After intravenous administration, the biodistribution of dextran-linker-DTPA-Gd(III) complexes differed significantly from that of GdDTPA. Reduction of the nitroxide by ascorbic acid was retarded in the polysaccharide derivatives, particularly in starch derivatized with both nitroxide and linker-DTPA-Cu(II). These agents showed contrast enhancement in the gastrointestinal tract of rabbits.