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PubMed1997

Multiple congenital anomalies, brain hypomyelination, and ocular albinism in a female with dup(X) (pter-->q24::q21.32-->qter) and random X inactivation.

We report on an 18-month-old girl with multiple congenital anomalies (prominence of the metopic suture, fine hair, club foot, absence of the 12th rib, brachydactyly) and severe mental retardation. The funduscopic examination showed diffuse retinal hypopigmentation. Brain magnetic resonance image (MRI) showed signs of diffuse hypomyelination. On cytogenetic and molecular evidence, the karyotype was 46,X,dirdup(X) (pter-->q24::q21.32-->qter). The duplication of the PLP gene, involved in Pelizaeus-Merzbacher disease, was confirmed by fluorescent in situ hybridization (FISH). Both cytogenetic and molecular studies on the X chromosome inactivation status indicated a random pattern in lymphocytes and fibroblasts. This patient appears to be the first case of a female bearing a large duplication of Xq with a random X inactivation. The phenotype of this patient is compared to that of previously reported cases with Xq duplication.

Abnormalities, Multiple↗
PubMed2004

The role of diffusion- and perfusion-weighted magnetic resonance imaging in drug development for ischemic stroke: from laboratory to clinics.

Ischemic stroke is a major cause of mortality and morbidity in industrialized countries and is almost always caused by occlusion of a cerebral artery by a clot. As the reversibly injured brain tissue evolves into irreversible infarction within a short period of time after onset of ischemia, it is extremely important and urgent to reverse the serious consequences of brain ischemia in the hyperacute phase when the ischemic brain tissue is still salvageable. Numerous thrombolytic and potentially neuroprotective agents have been studied in stroke patients with little success as the only approved therapy is thrombolysis with recombinant tissue plasminogen activator (r-tPA) within 3 h of stroke onset in highly selected patients (approximately 5 to 10 % of all acute stroke patients). One major obstacle in the development of effective therapies for ischemic stroke has been the lack of versatile imaging techniques. New magnetic resonance imaging (MRI) modalities, specially diffusion- and perfusion-weighted MRI (DWI and PWI, respectively) have been used in experimental studies with great success for over a decade and now are gradually entering clinical use. DWI and PWI can detect brain ischemia in the early phase in its full extent thus ensuring a definite diagnosis, allowing for follow-up of the ischemic lesion size over time with good spatial and temporal resolution, demonstrating perfusion deficit and reperfusion and the existence and the extent of penumbra while only requiring a few minutes of imaging time. DWI and PWI do not just give us the correct diagnosis of ischemic stroke, but allow us to acquire in vivo lesion size before therapeutic regimen is started and monitor the therapeutic efficacy thereafter, thus overcoming the potential pretreatment bias. We used DWI and PWI to evaluate novel therapeutic approaches for ischemic stroke in numerous experimental studies and lately in humans. With DWI and PWI, we are able to determine the in vivo efficacy (or lack of efficacy) of new therapeutic regiments (both neuroprotective and thrombolytic agents, or combination therapies) in a rapid, safe, and reliable way and in a relatively small number of well-selected, well-defined, and homogeneous patients. This approach may, therefore, significantly accelerate the development of new remedies for stroke patients.

Animals↗
PubMed2000

Rapid isotropic diffusion mapping without susceptibility artifacts: whole brain studies using diffusion-weighted single-shot STEAM MR imaging.

A subsecond magnetic resonance imaging (MRI) technique for isotropic diffusion mapping is described which, in contrast to echo-planar imaging (EPI), is insensitive to resonance offsets, i.e., tissue susceptibility differences, magnetic field inhomogeneities, and chemical shifts. It combines a diffusion-weighted (DW) spin-echo preparation period and a high-speed stimulated echo acquisition mode (STEAM) MRI sequence and yields single-shot images within measuring times of 559 msec (80 echoes). Here, diffusion encoding involved one scan without DW, three DW scans with b = 490 sec mm(-2), and three DW scans with b = 1000 sec mm(-2) (orthogonal gradient orientations). An automated on-line evaluation resulted in isotropic DW images as well as ADC maps (trace of the diffusion tensor). Experiments at 2.0 T covered the brain of healthy subjects in 20 contiguous sections of 6 mm thickness and 2.0 x 2.0 mm(2) in-plane resolution within a total measuring time of 78 sec. High-resolution studies at 1.0 x 1.0 mm(2) (interpolated from 2.0 x 1.0 mm(2) acquisitions) were obtained within 5 min 13 sec using four averages. In comparison with EPI, DW single-shot STEAM MRI exhibits only about half the SNR, but completely avoids regional signal losses, high intensity artifacts, and geometric distortions.

Adult↗
PubMed2002

Spontaneous intracranial hypotension in the absence of magnetic resonance imaging abnormalities.

BACKGROUND: Spontaneous intracranial hypotension (SIH) is a neurologic syndrome of unknown etiology, characterized by features of low cerebral spinal fluid (CSF) pressure, postural headache and magnetic resonance imaging (MRI) abnormalities. METHODS: Four symptomatic cases of SIH presented to our institution over a six-month period. Magnetic resonance imaging studies were performed in all four cases. Diagnostic lumbar puncture was done in all except one case. RESULTS: All of the patients on whom lumbar punctures were performed demonstrated low CSF pressure and CSF protein elevation with negative cultures and cytology. Three out of the four patients exhibited MRI findings of diffuse spinal and intracranial pachymeningeal gadolinium enhancement and extradural or subdural fluid collections. One patient had no MRI abnormalities despite prominent postural headache and reduced CSF pressure at lumbar puncture. All patients recovered with intravenous fluids and conservative treatment. CONCLUSIONS: Magnetic resonance imaging abnormalities are found in most, but not all patients, with SIH. Cerebral spinal fluid abnormalities can be detected even in patients with normal MRI studies. It is important to recognize the variability of imaging results in this usually benign disorder.

Adult↗
PubMed2002

[Measuring perfusion and diffusion in neuroradiology].

Neuroradiology should be regarded as a discipline with a strong focus on integral diagnosis of morphology and function of the central nervous system. With perfusion magnetic resonance imaging (P-MRI) and diffusion-weighted magnetic resonance imaging (DWI) the functional micro-structural analysis of the central nervous system has been made possible. So, disease processes may be characterised on a molecular level and P-MRI as well as DWI are now integrated in clinical routine diagnosis to improve therapy planning.

Brain↗
PubMed1997

Diffuse infiltrating astrocytoma of the cervicomedullary region: clinicopathologic entity.

Recent imaging and neurosurgical techniques have led to an improvement in the surgical management of children with brainstem tumors (BSTs). Many children with tumors previously considered 'inoperable' can now benefit from surgery. Increased experience has brought about new theories concerning the growth pattern, natural history, classification and optimal management of these tumors. Cervicomedullary (CM) tumors commonly have an indolent presentation reflecting either medullary or cervical spinal cord dysfunction and tend to arise in the upper cervical cord growing into the medulla in a posterior exophytic fashion. Intrinsic BSTs often present acutely with cranial nerve dysfunction and generally arise in the pons with a diffuse infiltrating growth pattern. A 21-month-old patient had developed feeding difficulty and reactive airway disease at approximately 8 months of age. MRI showed a diffuse, nonenhancing tumor in the CM region. Following radical resection, and an unremarkable perioperative course, he aspirated, developed pulmonary insufficiency and expired. Postmortem examination revealed a low-grade diffuse fibrillary astrocytoma extending from C6 to the medulla. The medullary portion arose in a paramedian location and infiltrated dorsally into the fourth ventricle, the obex, the leptomeninges, and the adjacent cerebellum. This case demonstrates the growth pattern of a distinct subset of CM tumors that behave in a manner similar to intrinsic diffuse BST. Future identification of these subsets by a careful analysis of the clinical presentation and MRI images will enable better operative planning and optimal management.

Astrocytoma↗
PubMed1997

Case report: subependymal diffuse heterotopia. Clinical, EEG, and neuroimaging findings.

We report the case of a 41 year-old woman with a slight mental retardation and epilepsy. MRI showed a diffuse subependymal heterotopia. The cognitive level supports the view that the ectopic cells are probably not important for the normal cortical functions but that they are likely able to maintain some of the electric properties of normal neurons, even if with altered discharge modalities. The genetic etiology of subependymal neuronal migration disorders is discussed. This is the second reported case of diffuse subependymal heterotopia in a female patient.

Adult↗
PubMed2001

Comparison of metabolite levels and water diffusion between cortical and subcortical strokes as monitored by MRI and MRS.

UNLABELLED: Labelle M, Khiat A, Durocher A, et al. Comparison of metabolite levels and water diffusion between cortical and subcortical strokes as monitored by MRI and MRS. Invest Radiol 2001;36:155-163. RATIONALE AND OBJECTIVES: Proton magnetic resonance spectroscopy (MRS) and functional imaging techniques are increasingly recognized as useful tools for the characterization of strokes. The aim of this study was to compare cortical and subcortical (lacunar) strokes by MRS and diffusion-weighted imaging (DWI) experiments as a function of time. METHODS: Single-voxel MRS, DWI, and perfusion-weighted imaging data were recorded on patients with cortical (n = 7) or subcortical (n = 7) strokes in the acute, subacute, and chronic periods. Magnetic resonance spectra were acquired in three regions: hyperintense DWI area, adjacent area with normal DWI intensity, and contralateral area. Neurological deficits were estimated by the National Institutes of Health Stroke Scale. RESULTS: Decreases in N-acetylaspartate, choline-containing compounds, and creatine/phosphocreatine signal intensity as well as the presence of lactate were observed at all times in the hyperintense DWI area of all lesions. Small decreases were measured in the subacute and chronic phases for the adjacent area of cortical strokes but not for the adjacent area of subcortical strokes. The existence of a surrounding affected area in subcortical strokes is deduced from a combination of MRS and DWI results, possibly corresponding to the ischemic penumbra. Differences were found between the two types of lesion, especially an increased time variability of apparent diffusion coefficients in subcortical strokes. CONCLUSIONS: Magnetic resonance spectroscopy provides evidence for the existence of affected tissue outside the hyperintense DWI regions in subcortical strokes. Cortical and subcortical strokes display different DWI and MRS characteristics.

Adult↗
PubMed1998

Shrinking spinal cord following transverse myelopathy in a patient with systemic lupus erythematosus and the phospholipid antibody syndrome.

A 38-year-old woman with systemic lupus erythematosus and the phospholipid antibody syndrome was admitted because of rapidly evolving symptoms consistent with a transverse myelopathy at the TH9/10 level. Magnetic resonance imaging (MRI) showed slight diffuse swelling and increased signal intensity of the spinal cord. She was treated with high dose methylprednisolone plus azathioprine and aspirin. Four months later she had achieved almost complete remission with minimal residual sphincter disturbances. Despite the clinical recovery, repeated MRI at 4 months and 4 years showed diffuse and irreversible atrophy of the entire spinal cord.

Adult↗
PubMed2003

Magnetic resonance imaging in experimental models of brain disorders.

This review gives an overview of the application of magnetic resonance imaging (MRI) in experimental models of brain disorders. MRI is a noninvasive and versatile imaging modality that allows longitudinal and three-dimensional assessment of tissue morphology, metabolism, physiology, and function. MRI can be sensitized to proton density, T1, T2, susceptibility contrast, magnetization transfer, diffusion, perfusion, and flow. The combination of different MRI approaches (e.g., diffusion-weighted MRI, perfusion MRI, functional MRI, cell-specific MRI, and molecular MRI) allows in vivo multiparametric assessment of the pathophysiology, recovery mechanisms, and treatment strategies in experimental models of stroke, brain tumors, multiple sclerosis, neurodegenerative diseases, traumatic brain injury, epilepsy, and other brain disorders. This report reviews established MRI methods as well as promising developments in MRI research that have advanced and continue to improve our understanding of neurologic diseases and that are believed to contribute to the development of recovery improving strategies.

Animals↗
PubMed2003

Cerebellar ataxia and leukoencephalopathy associated with cobalamin deficiency.

We report a patient who presented progressive cerebellar ataxia associated with vitamin B(12) deficiency. Brain magnetic resonance imaging (MRI) demonstrated a diffuse leukoencephalopathy. Six months after the initiation of methylcobalamin therapy, there were clinical improvement and reduction in the MRI abnormalities.

Brain Stem↗
PubMedDate not supplied

Acute transverse myelitis caused by Coxsackie virus B5 infection.

A 6-year-old boy developed symptoms of rapidly progressive paraplegia, associated with bowel and urinary dysfunction, but without sensory loss. Magnetic resonance imaging (MRI) examination showed diffuse swelling of the lower spinal cord on T1-weighted images. Based on the clinical presentation and MRI findings, a diagnosis of acute transverse myelitis was made. The serum titer of neutralizing antibody against Coxsackie virus B5 rose from 1/4 on admission to 1/256 1 month later and Coxsackie virus B5 was isolated from stool samples. This case serves as a reminder that acute transverse myelitis can be a rare clinical manifestation of Coxsackie virus B5 infection.

Antibodies, Viral↗
PubMed2002

Unusual fatty infiltration of the soleus muscle in a patient with congenital nemaline myopathy: fat-suppression muscle MRI.

A 27-year-old man developed gait disturbance over a three-year period. Histochemical analysis suggested nemaline bodies, type I fiber atrophy and type II fiber hypertrophy. Conventional magnetic resonance imaging (MRI) showed a severe degree of homogenous hyperintensity in the soleus muscle. Fat-suppression MRI exhibited marked diffuse hypointensity in the soleus muscle. MRIs demonstrated unusual fatty proliferation of the soleus muscle. Fat-suppression MRI of skeletal muscles is beneficial in evaluating the accurate topography and degree of fatty infiltration. Radiological patterns of muscle damage are variable in patients with congenital nemaline myopathy, similar to the heterogeneous clinical aspects.

Adipose Tissue↗
PubMed1999

Regional differences in diffusion abnormality in cerebral white matter lesions in patients with vascular dementia of the Binswanger type and Alzheimer's disease.

We investigated changes in water diffusion in the cerebral white matter of 14 patients with vascular dementia of the Binswanger type (VDBT) and ten patients with Alzheimer's disease (AD) with periventricular hyperintensity (PVH) lesions using diffusion-weighted magnetic resonance imaging (MRI) and studied the pathophysiological differences between white matter lesions found in these two conditions. Apparent diffusion coefficients (ADCs) in the anterior and posterior white matter and the genu and splenium of the corpus callosum were significantly higher in both groups of patients than in the 12 age-matched controls, and ADC values in VDBT and AD groups were almost the same. ADC ratios, defined as diffusion restricted perpendicular to the direction of nerve fibers, were also significantly higher in the patients than in the control subjects. However, there were regional differences in ADC ratios in the two conditions, with ratios in VDBT being higher in the anterior portions of the white matter but ratios in AD were higher in the posterior portions. The diffusion-weighted MRI technique may be useful in the differential diagnosis of VDBT and AD with white matter lesions.

Aged↗
PubMed2006

Evaluation of parenchymal changes at the operation site with early postoperative brain diffusion-weighted magnetic resonance imaging.

PURPOSE: To evaluate diffusion changes in the brain parenchyma at the operation site during the first 24 hours following surgery. MATERIALS AND METHODS: The study group consisted of 52 patients, 39 who had tumor resection surgery and 13 who had epilepsy surgery. Early postoperative magnetic resonance imaging (MRI) included diffusion-weighted imaging (DWI) and routine contrast-enhanced cranial MRI, together with T2* weighted images on a 3T system. DWI findings and the presence of hemorrhage in the brain parenchyma were evaluated. Correlation between the findings, the primary lesion leading to surgery, and operation site were evaluated. RESULTS: Diffusion restriction in the parenchyma surrounding the resection cavity was seen in 17 tumor patients (32.7%, n=52) and in 8 epilepsy patients (15.4%, n=52). DWI showed increased diffusion in 7 patients and no abnormality in 4 patients. Twenty patients showed restricted diffusion pattern related to hemorrhage (38.5%, n=52). CONCLUSION: Restricted diffusion was the most common abnormality observed in the early postoperative DWI of brain parenchyma at the operation site after surgery, which suggested tissue injury caused by surgery. Yet, hemorrhaging in the operation bed can constitute another cause of a reduced apparent diffusion coefficient (ADC) value. Increased diffusion and normal diffusion can also be observed, though rarely.

Adolescent↗
PubMed2003

Hyperpolarized helium-3 gas magnetic resonance imaging of the lung.

3He magnetic resonance imaging (MRI) is capable of producing new and regional information on normal and abnormal lung ventilation. The basis of 3He MRI involves "optical pumping" to hyperpolarize the 3He nuclei by photon angular momentum transfer. The hyperpolarized gas is administered via inhalation. 3He is an inert, nontoxic noble gas and absorbed in less than 0.1%. Imaging consists of a four-step protocol. 1) Gas density 3He MRI with high spatial resolution displays the distribution of a 3He bolus in a 10-second breath-hold. An almost homogeneous distribution is regarded as normal. Patients with lung diseases show multiple ventilation defects. 3He MRI has been shown to be more sensitive than proton MRI, computed tomography, nuclear medicine or pulmonary function testing for detection of ventilation defects. 2) Dynamic imaging 3He MRI with high temporal resolution shows the dynamic distribution of ventilation during continuous breathing after inhalation of a single breath of 3He gas. Homogeneous and fast distribution is regarded as normal, whereas patients show irregular and delayed patterns with redistribution and air trapping. 3) Diffusion-weighted 3He MRI provides a new measure for pulmonary microstructure because the apparent diffusion coefficient (ADC) reflects lung structure. Normal ADC values are less than 0.25 cm2/s and are increased in fibrosis and emphysema (0.3-0.9 cm2/s). 4) Oxygen-sensitive 3He MRI allows for regional and temporal analysis of intrapulmonary Pao2, which reflects regional pulmonary perfusion, ventilation-perfusion ratio, and oxygen uptake. In patients, an inhomogeneous Po2 distribution indicates alterations of ventilation-perfusion matching. Based on increased experience, 3He MRI can be regarded as a highly promising tool for functional analysis of ventilation. The clinical significance of the increase in sensitivity and sensitivity associated with 3He MRI is yet to be determined.

Helium↗
PubMed1999

[Neuroradiologic diagnosis in acute stroke].

Noninvasive diagnostic procedures as spiral-CT (CT-angiography and perfusion-CT) as well as MRI-techniques (diffusion-imaging, perfusion-imaging and MR-angiography) have enriched the diagnostic modalities in acute stroke. Angiography by MRI or CT has replaced digital subtraction angiography in most acute stroke cases. Despite of the advantages of MRI, CT still remains the procedure of choice in acute stroke. 1. Acute hematoma is easily detected by CT. 2. Occlusion of the main arterial stems are identified by CT-angiography. CT fulfills all the requirements for therapeutic decisions in acute stroke.

Acute Disease↗
PubMed1991

Update on technology diffusion.

Magnetic resonance imaging (MRI) continues to expand in influence as a diagnostic tool, with the number of units installed in the United States growing rapidly, according to an AHA technology assessment report. Technology assessment is being used more and more in decision making regarding the use of MRI and other diagnostic technologies. Two perspectives on the phenomenon are explored.

American Hospital Association↗