High Signal (high + signal)

Distribution by Scientific Domains
Distribution within Medical Sciences

Terms modified by High Signal

  • high signal change
  • high signal intensity

  • Selected Abstracts


    Cerebral cortical laminar necrosis on diffusion-weighted MRI in hypoglycaemic encephalopathy

    DIABETIC MEDICINE, Issue 8 2005
    Y. Yoneda
    Abstract Background Laminar necrosis of the cerebral cortex characterized neuropathologically by delayed selective neuronal necrosis occurs in hypoglycaemic encephalopathy and other brain diseases. Case report A 37-year-old male with insulin-treated Type 1 diabetes mellitus developed hypoglycaemic encephalopathy associated with respiratory failure. Brain diffusion-weighted MRI during the subacute period demonstrated high signals along the cerebral cortex. Brain single-photon emission computed tomography showed diffuse, severe cerebral hypoperfusion. The patient remained comatose and died 1 month later. Conclusions High signals along the cortical bands on diffusion-weighted MRI suggest cortical laminar necrosis, although a postmortem examination was unavailable. Sustained hypoglycaemic brain injury, possibly associated with respiratory hypoxia, may be the underlying mechanism. [source]


    MR imaging methods for assessing fetal brain development

    DEVELOPMENTAL NEUROBIOLOGY, Issue 6 2008
    Mary Rutherford
    Abstract Fetal magnetic resonance imaging provides an ideal tool for investigating growth and development of the brain in vivo. Current imaging methods have been hampered by fetal motion but recent advances in image acquisition can produce high signal to noise, high resolution 3-dimensional datasets suitable for objective quantification by state of the art post acquisition computer programs. Continuing development of imaging techniques will allow a unique insight into the developing brain, more specifically process of cell migration, axonal pathway formation, and cortical maturation. Accurate quantification of these developmental processes in the normal fetus will allow us to identify subtle deviations from normal during the second and third trimester of pregnancy either in the compromised fetus or in infants born prematurely. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source]


    Vasoconstriction as the Etiology of Hypercalcemia-induced Seizures

    EPILEPSIA, Issue 5 2004
    Tsung-Hua Chen
    Summary: Purpose: Reversible cerebral vasoconstriction has been hypothesized to be the etiology of seizures due to hypercalcemia, but angiographic studies documenting vasoconstriction have not previously been available. Methods: We present a 43-year-old woman who had frequent seizures that later evolved to status epilepticus with marked hypercalcemia at the time of the seizures. Results: Magnetic resonance imaging (MRI) of the patient's brain revealed high signal changes in T2 -weighted imaging, fluorescence-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) over the bilateral occipital and thalamic areas. Cerebral angiography showed blood vessels narrowing, disappearing altogether over the right posterior cerebral artery (PCA) branch, which is compatible with vasoconstriction. Vasoconstriction caused the MRI high signal in the occipital area, which was associated with subsequent periodic lateralized epileptic discharges. The patient's clinical condition improved with management of seizures and hypercalcemia. A second brain MRI 2 weeks later revealed complete resolution of the high-signal lesions. Follow-up cerebral angiography study also showed total recovery of vasoconstriction. Conclusions: The sequence of events suggests the hypothesis that reversible cerebral vasoconstriction may play a role in hypercalcemia-induced seizures. [source]


    Diffusion-weighted MRI of cholesteatomas of the petrous bone

    JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2002
    Clemens Fitzek MD
    Abstract Purpose To investigate if primary cholesteatomas of the petrous bone show high signal in diffusion-weighted imaging (DWI). Materials and Methods In this blinded study, we compared 15 patients with clinically certain cases and later surgically proven cholesteatomas vs. 12 patients with clinically acute otitis of the middle ear and 20 volunteers without petrous bone disease. Two blinded readers without knowledge of the clinical data decided in consensus agreement whether there was a pathologic signal increase in the petrous bone in an anisotropic single-shot echo-planar imaging (EPI) DWI sequence, an artifact, or no signal increase. Results Thirteen of 15 patients with cholesteatomas showed bright signal in EPI DWI, whereas 10 of 12 patients with acute otitis media and all volunteers presented the usual low signal of petrous bone. Conclusion EPI DWI is a fast diagnostic method that may be an additional valuable tool in the workup of suspected cholesteatomas. The ability of this technique to differentiate between cholesteatomas and granulomas or chronic otitis is not yet available. J. Magn. Reson. Imaging 2002;15:636,641. © 2002 Wiley-Liss, Inc. [source]


    Cranial magnetic resonance imaging of Wolfram (DIDMOAD) syndrome

    JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2 2005
    E Pakdemirli
    Summary Wolfram syndrome is a rare neurodegenerative disorder characterized by diabetes insipidus, diabetes mellitus, optic atrophy and deafness (DIDMOAD). A wide spectrum of abnormalities of the central nervous system, urinary tract and endocrine glands is also observed. We report cranial MRI findings in a 32-year-old female patient with Wolfram syndrome. In addition to the classical features, including absence of the normal high signal of the neurohypophysis, atrophy of visual pathways, the brainstem, cerebellum and cerebral cortex, we observed bilateral hyperintensity on proton density- and T2- weighted images related to the optic radiations in the periventricular white matter of the temporal and parieto-occipital lobes, which may reflect gliosis pathologically. [source]


    In vitro1H magnetic resonance spectroscopy differences between meningeoma and astrocytoma

    JOURNAL OF NEUROCHEMISTRY, Issue 2003
    K. Likav, anová
    Tumor transformation of the human brain cells causes different biochemical changes. Here we employed 1H magnetic resonance spectroscopy to compare the presence of low molecular weight metabolites in meningeoma and astrocytoma tumors by measuring perchloric acid extracts of the cells. In 1H spectra of meningeoma we detected high signal from lactate but were unable to detect any signal of NAA and creatine. In contrast, astrocytoma samples revealed significantly higher level of inositol and glycine and significant decrease in glutamate and glutamine compared with meningeoma but no presence of taurine. Our results suggest that 1H MRS can provide useful information about biochemical changes in different types of brain tumors. Acknowledgements: This work was supported by the Grant Category C and Comenius University Grant No. X/2003. [source]


    Diffusion Magnetic Resonance Imaging in Intermediate Form of Maple Syrup Urine Disease

    JOURNAL OF NEUROIMAGING, Issue 4 2002
    R. N. Sener
    ABSTRACT An 8-year-old boy with the intermediate variant of maple syrup urine disease is reported. On b= 1000 s/mm2 (heavily diffusion weighted) images of diffusion magnetic resonance imaging, there was symmetric high signal in the globus pallidus, mesencephalon, dorsal pons, and nucleus dentatus, consistent with restriction of the mobility of water molecules. Apparent diffusion coefficient (ADC) maps revealed low ADC values ranging from 0.42 to 0.56 ?10,3mm2/s in these regions, compared to those of apparently unaffected regions in the brain parenchyma ranging from 0.63 to 0.97 ?10,3 mm 2/s. It is suggested that the areas of increased signal (and low ADC values) are the result of dysmyelination as a reflection of disorganized tissue integrity. [source]


    Ultrashort TE T1rho (UTE T1rho) imaging of the Achilles tendon and meniscus

    MAGNETIC RESONANCE IN MEDICINE, Issue 3 2010
    Jiang Du
    Abstract In this study, we report the use of a novel ultrashort echo time T1rhoT1 sequence that combines a spin-lock preparation pulse with a two-dimensional ultrashort echo time sequence of a nominal echo time 8 ,sec. The ultrashort echo time- T1rho sequence was employed to quantify T1rho in short T2 tissues including the Achilles tendon and the meniscus. T1rho dispersion was investigated by varying the spin-lock field strength. Preliminary results on six cadaveric ankle specimens and five healthy volunteers show that the ultrashort echo time- T1rho sequence provides high signal and contrast for both the Achilles tendon and the meniscus. The mean T1rho of the Achilles tendon ranged from 3.06 ± 0.51 msec for healthy volunteers to 5.22 ± 0.58 msec for cadaveric specimens. T1rho increased to 8.99 ± 0.24 msec in one specimen with tendon degeneration. A mean T1rho of 7.98 ± 1.43 msec was observed in the meniscus of the healthy volunteers. There was significant T1rho dispersion in both the Achilles tendon and the meniscus. Mean T1rho increased from 2.06 ± 0.23 to 7.85 ± 0.74 msec in normal Achilles tendon and from 7.08 ± 0.64 to 13.42 ± 0.93 msec in normal meniscus when the spin-lock field was increased from 250 to 1,000 Hz. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source]


    Increased asymmetric pulvinar magnetic resonance imaging signals in Creutzfeldt,Jakob disease with florid plaques following a cadaveric dura mater graft

    NEUROPATHOLOGY, Issue 1 2006
    Yoshinobu Wakisaka
    A 9-year-old Japanese girl received a cadaveric dura mater graft during surgery following a head injury with brain contusion. She continued to do well, but when she became 19-years-old, she gradually showed a violent character and was treated in a psychiatric hospital. Another 6 years later, 200 months after the procedure, she developed a progressive gait ataxia, which subsequently led to her death within 10 months of onset. An autopsy showed she had CJD. This patient represents an atypical case of dura-associated CJD (dCJD) with unusual clinicopathological features including the late occurrence of myoclonus, an absence of periodic synchronous discharges in the electroencephalogram, and the presence of widespread florid plaques. However, our detection of an asymmetrical increase in the MRI-derived images of pulvinar nuclei has not been previously observed in other atypical cases of dCJD. Because atypical dCJD cases share several clinicopathological features with those of vCJD, and because asymmetrical hyperintense signals in the pulvinar have been observed in some neuropathologically confirmed vCJD cases, we had some difficulty in a differential diagnosis between atypical dCJD and vCJD. This is the first atypical dCJD case showing a pulvinar high signal compared with all other basal ganglia on MRI. [source]


    Three-dimensional MRI of cerebral projections in rat brain in vivo after intracortical injection of MnCl2

    NMR IN BIOMEDICINE, Issue 5 2003
    Peter R. Allegrini
    Abstract In this study we investigated the potential of in vivo MRI detection of axonal Mn2+ transport for tracing neuronal projections originating in the sensorimotor cortex in healthy and lesioned rat brains. Special attention was given to the potential of visualizing neuronal sprouting of central nervous system across the midline. After injecting unchelated MnCl2 into the forelimb area of sensorimotor cortex of 18 healthy and 10 lesioned rats corticofugal projections could be traced through the internal capsule to the cerebral peduncle and the pyramidal decussation. Although the neuronal tract was visible as early as 6,h after MnCl2 injection, best contrast was achieved after 24,48,h. Beside the cortico-spinal tract, the cortico-thalamic fibres were also visualized by anterograde Mn2+ transport. Cortico-striatal fibres were partially masked by the very high signal near the MnCl2 injection site but could be discerned as well. Slight, diffuse signal enhancement of cortical tissue contralateral to the MnCl2 injection site in healthy rat brains suggests interhemispheric connections or passive diffusion of Mn2+. However, enhanced fibre tract contrast connecting both hemispheres was visible 16 weeks after onset of focal photothrombotic cortical injury. In conclusion our study has shown that we were able to visualize reproducibly the main descending corticofugal projections and interhemispheric connections by non-invasive MRI after localized injection of MnCl2. The appearence of interhemispheric Mn2+ -enhanced fibres after photothrombotic focal injury indicates that the method may bear potential to follow non-invasively gross plastic changes of connectivity in the brain after injury. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    The Value of Enhanced Magnetic Resonance Imaging in the Evaluation of Endocochlear Disease,

    THE LARYNGOSCOPE, Issue 1 2002
    Joseph L. Hegarty MD
    Abstract Background Gadolinium-enhanced magnetic resonance imaging (GdMRI) is routinely used in the evaluation and management of suspected retrocochlear pathology such as vestibular schwannoma. However, its value in the evaluation and diagnosis of cochlear pathology associated with sensorineural hearing loss (SNHL) has been less clear. Study Design Retrospective review of case histories and imaging studies of patients with SNHL and cochlear enhancement on GdMRI diagnosed between 1998 and 2000. Results Five patients with SNHL who required gadolinium administration to establish the diagnosis of endocochlear disease were identified. Diagnosed lesions included an intralabyrinthine schwannoma, intracochlear hemorrhage, radiation-induced ischemic change, autoimmune labyrinthitis, and meningogenic labyrinthitis. In these illustrative cases, the GdMRI demonstrated intrinsic high signal or contrast enhancement within the cochlea and labyrinth in the absence of a retrocochlear mass. In one patient with meningogenic labyrinthitis, cochlear enhancement on MRI led to prompt cochlear implantation before the potential development of cochlear ossification. Conclusion Our experience suggests that GdMRI plays a crucial role in the diagnosis of cochlear pathology associated with sensorineural hearing loss and may directly impact patient management. [source]


    Angiocentric Neuroepithelial Tumor (ANET): A New Epilepsy-Related Clinicopathological Entity with Distinctive MRI

    BRAIN PATHOLOGY, Issue 4 2005
    Arielle Lellouch-Tubiana MD
    Several types of glioneuronal tumors are known to induce intractable partial seizures in children and adults. The most frequent are dysembryoplastic neuroepithelial tumors (DNETs) and gangliogliomas. We report here a new clinicopathological entity within the spectrum of glioneuronal tumors observed in 10 children who underwent surgery for refractory epilepsy. These tumors demonstrate a unique, pathognomonic histological pattern and a specific appearance at magnetic resonance imaging (MRI). The most striking neuropathological feature is an angiocentric polarity of the tumor with gliofibrillary acidic protein (GFAP) positive fusiform and bipolar astrocytic cells arranged around blood vessels (perivascular cuffing with tumoral astrocytes). Characteristic MRI findings include involvement of cortical gray and white matter, intrinsically high signal on T1-weighted images, as well as a stalk like extension to the ventricle. Immunohistochemical neuronal markers (neurofilament protein, synaptophysin and chromogranin) confirm the presence of a neuronal cell component. Therefore, the term angiocentric neuroepithelial tumor (ANET) is proposed. [source]


    Cerebral cortical laminar necrosis on diffusion-weighted MRI in hypoglycaemic encephalopathy

    DIABETIC MEDICINE, Issue 8 2005
    Y. Yoneda
    Abstract Background Laminar necrosis of the cerebral cortex characterized neuropathologically by delayed selective neuronal necrosis occurs in hypoglycaemic encephalopathy and other brain diseases. Case report A 37-year-old male with insulin-treated Type 1 diabetes mellitus developed hypoglycaemic encephalopathy associated with respiratory failure. Brain diffusion-weighted MRI during the subacute period demonstrated high signals along the cerebral cortex. Brain single-photon emission computed tomography showed diffuse, severe cerebral hypoperfusion. The patient remained comatose and died 1 month later. Conclusions High signals along the cortical bands on diffusion-weighted MRI suggest cortical laminar necrosis, although a postmortem examination was unavailable. Sustained hypoglycaemic brain injury, possibly associated with respiratory hypoxia, may be the underlying mechanism. [source]