نتایج جستجو برای: restricted diffusion
تعداد نتایج: 278753 فیلتر نتایج به سال:
The modulation of spin phase produced by Carr-Purcell-Meiboom-Gill (CPMG) sequence in combination with constant magnetic field gradient is appropriate to probe the displacement power spectrum (DPS). The spin-echo attenuation is directly proportional to the DPS value at the applied modulation frequency. Relaxation and selective excitation effects can be factored out while probing the DPS. The mo...
During the acute stage of carbon monoxide poisoning, diffusion MR images obtained at b=1000 s/mm2 revealed high signal intensity lesions in the white matter, consistent with restricted diffusion. Low apparent diffusion coefficient values (0.18-0.34 x 10(-3) mm2/s) were noted in the affected white matter regions. Follow-up MR imaging performed 16 days later revealed disappearance of white matter...
Transient global amnesia syndrome was initially described more than a century ago. Although the clinical syndrome is easily recognized and highly consistent in its characteristic features, the underlying pathophysiology has remained elusive. Proposed mechanisms include focal ischemic lesions or local nonischemic energy failures. Diffusion-weighted imaging has been able to demonstrate focal area...
BACKGROUND AND PURPOSE Neuroaxonal dystrophy is a rare progressive disorder of childhood characterized by mental deterioration and seizures. The diffusion-weighted and conventional MR imaging findings are reported for six cases. METHODS Six patients aged 19 months to 9 years with proved neuroaxonal dystrophy (one with the infantile form, five juvenile forms) underwent imaging at 1.5 T. Echo-p...
BACKGROUND Hereditary diffuse leukodystrophy with spheroids is a rare type of leukoencephalopathy. Mutations in the colony stimulating factor 1 receptor have recently been identified to be the cause of this microgliopathy. Clinical and radiological presentation can often misguide physicians during the diagnosis of patients with this underdiagnosed disease. CASE PRESENTATION We present a 29 ye...
SUMMARY A 60-year-old woman developed right-eye vision loss secondary to rhinocerebral mucormycosis. Routine MR imaging sequences including enhanced MR imaging showed normal optic nerves, but a diffusion-weighted sequence and apparent diffusion coefficient maps revealed markedly restricted diffusion in the right optic nerve. This MR imaging abnormality of optic nerve infarction due to mucormyco...
BACKGROUND AND PURPOSE The pathogenesis of cerebral venous infarction (CVI) remains controversial, with uncertainty over whether cytotoxic edema plays a role. Recent animal studies have shown that cytotoxic edema reliably occurs in acute CVI and precedes the onset of vasogenic edema. Our hypothesis was that cytotoxic edema would also occur in acute human CVI and would be detectable as an area o...
The diffusion-weighted (DW) magnetic resonance (MR) imaging findings of a patient with subacute stage of heroin-induced vacuolating myelinopathy are reported. The diffuse decrease of apparent diffusion coefficient (ADC) of the white matter on DW imaging is attributed to restricted water diffusion, which is known to be caused by fluid entrapment within the myelin lamellae without demyelination.
Over the last decade, there has been a significant increase in the number of high-magnetic-field MRI magnets. However, the exact effect of a high magnetic field strength (B0 ) on diffusion-weighted MR signals is not yet fully understood. The goal of this study was to investigate the influence of different high magnetic field strengths (9.4 T and 14.1 T) and diffusion times (9, 11, 13, 15, 17 an...
We describe a case of carbon monoxide poisoning that led to pallidoreticular damage and delayed leukoencephalopathy. Serial diffusion-weighted MR imaging was performed. A restricted water diffusion pattern was demonstrated in the globus pallidus and substantia nigra in the early stage. Diffusion-weighted imaging is useful for early identification of the effects of acute carbon monoxide poisoning.
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