Neuronal damage in the interval form of CO poisoning determined by serial diffusion weighted magnetic resonance imaging plus 1H-magnetic resonance spectroscopy

In a patient with the interval form of carbon monoxide (CO) poisoning diffusion weighted MRI and proton magnetic resonance spectroscopy (1H-MRS) were serially performed immediately after the appearance of delayed sequelae (the 23rd day after exposure). During the period in which few clear findings were evident on MRI T2 weighted images, a high signal area in the cerebral white matter and relative decrease in the apparent diffusion coefficient (ADCav) were already apparent on diffusion weighted images, with these findings thought to sensitively reflect the tissue injury associated with the onset of sequelae. The decrease in relative ADCav persisted until the 38th day after exposure. Subsequently, ADCav gradually increased, and in the cerebral white matter showed higher values in the 118th day after exposure than immediately after the onset of sequelae. During this period, on 1H-MRS choline containing compounds showed persistently high values throughout the course, with N-acetylaspartate depletion and the appearance of a lactate peak later in the course. These findings, with regional specificity in the cerebral white matter, reflect the developmental process of the white matter lesions in the interval form of CO poisoning in which demyelination progresses leading to neuronal necrosis. Serial diffusion weighted imaging plus 1H-MRS measurements are useful in determining the tissue damage and long term outcome of delayed sequelae associated with the interval form of CO poisoning.     

Rapidly progressive vanishing white matter disease in a child with previously inconspicuous brain MRI

In this pediatric case of vanishing white matter disease with early onset, rapidly progressive course, and fatal outcome, the white matter vanishing process in patient was for the first time documented morphologically in detail: An initial magnetic resonance imaging documented a normal appearing brain maturation. Rapid progressive brain lesions initiated morphologically DE NOVO in the former well myelinated deep white matter were observed six months later after disease onset, including concentric ongoing signs of restricted proton diffusion cytotoxic edema on diffusion weighted imaging. Cyst-like defects at the lesion center of the deep white matter were detected more clearly on MRI ten months later. A pathomechanism like tumor necrosis factor induced oligodendrocyte apoptosis and primary demyelination was postulated. The case demonstrates that in the presence of clinically progressive symptoms, the development of VWM is possible even if first MRI findings are negative.     

Modeling the orientation distribution function by mixtures of angular central Gaussian distributions

In this paper we develop a tensor mixture model for diffusion weighted imaging data using an automatic model order selection criterion for the number of tensor components in a voxel. We show that the weighted orientation distribution function for this model can be expanded into a mixture of angular central Gaussian distributions. We investigate properties of this model in extensive simulations and in a high angular resolution scan of a human brain. The results suggest that the model improves imaging of cerebral fiber tracts. In addition, inference on canonical model parameters could potentially provide novel clinical markers of altered white matter. Software to compute the tensor mixture model from diffusion weighted MRI data is made available in the programming language R.     

A case of deep cerebral venous thrombosis with sudden convulsion after delivery]

A 25-year-old woman was admitted to our hospital because of convulsions after delivering a baby. Her neurological examination revealed a disturbance of consciousness and weakness in both arms. A brain magnetic resonance imaging scan (MRI) showed thrombosis of the left transverse sinus and many patchy high signals at bilateral basal ganglia and subcortical areas. A digital subtraction angiogram (DSA) of the brain revealed a defect at the left transverse sinus, congestion of the cerebral venous flow at the vein of Galen and vasospastic changes at both posterior cerebral arteries. After treating the patient with a venous infusion of heparin, nicardipine and phenytoin, her neurological deficits improved within a day. When MRI and DSA were repeated 2 weeks later, the abnormal lesions had disappeared. These findings suggest that venous thrombosis and vasospasm had the pathogenesis of eclampsia in this case.     

Doxycycline treatment in a neonatal rat model of hypoxia-ischemia reduces cerebral tissue and white matter injury: a longitudinal magnetic resonance imaging study

Doxycycline may potentially be a neuroprotective treatment for neonatal hypoxic-ischemic brain injury through its anti-inflammatory effects. The aim of this study was to examine any long-term neuroprotection by doxycycline treatment on cerebral gray and white matter. Hypoxic-ischemic brain injury was induced in 7-day-old rats. Pups were treated with either doxycycline (HI+doxy) or saline (HI+vehicle) by intraperitoneal injection at 1 h after hypoxia-ischemia (HI). At 6 h after HI, MnCl(2) was injected intraperitoneally for later manganese-enhanced magnetic resonance imaging (MRI). MRI was performed with diffusion-weighted imaging on day 1 and T(1) -weighted imaging and diffusion tensor imaging at 7, 21 and 42 days after HI. Animals were killed after MRI on day 42 and histological examinations of the brains were performed. There was a tendency towards lower lesion volumes on diffusion maps among HI+doxy than HI+vehicle rats at 1 day after HI. Volumetric MRI showed increasing differences between groups with time after HI, with less cyst formation and less cerebral tissue loss among HI+doxy than HI+vehicle pups. HI+doxy pups had less manganese enhancement on day 7 after HI, indicating reduced inflammation. HI+doxy pups had higher fractional anisotropy on diffusion tensor imaging in major white matter tracts in the injured hemisphere than HI+vehicle pups, indicating less injury to white matter and better myelination. Histological examinations supported the MRI results. Lesion size on early MRI was highly correlated with final injury measures. In conclusion, a single dose of doxycycline reduced long-term cerebral tissue loss and white matter injury after neonatal HI, with an increasing effect of treatment with time after injury.     

A case of cerebral venous thrombosis with reversible brain parenchymal lesions: usefulness of diffusion weighted imaging and measurement of apparent diffusion coefficient]

A 47-year-old man with a history of thrombophlebitis of his left leg for several years presented with a mild left hemiparesis and ipsilateral hypesthesia. Magnetic resonance imaging showed subacute thrombosis of the superior sagittal sinus and a cortical vein of the right cerebral hemisphere. A linear hyperintense area was found in the white matter of the right postcentral gyrus on T 2- and diffusion weighted axial imagings on the 7 days after the onset. The patient was treated conservatively, and his clinical course was uneventful. His neurological dysfunctions recovered within approximately three weeks after the onset. The white matter lesion in the right postcentral gyrus also disappeared one month later. The apparent diffusion coefficients (ADCs) in the white matter of the pre- and postcentral gyrus were measured bilaterally on the ADC mapping imaging. In the subacute stage, the ADC values in the white matter of the right pre- and postcentral gyrus were 0.50 x 10(-3) mm2/sec and 0.91 x 10(-3) mm2/sec, respectively. The %ADC indicating the ratio of ADC value of the lesion to that of the contralateral brain tissue was calculated. The %ADCs in the white matter of the pre- and postcentral gyrus were 64.9% and 124.5% respectively. In the chronic stage, the ADC values in the white matter of the right pre- and postcentral gyrus were 0.96 x 10(-3) mm2/sec and 0.99 x 10(-3) mm2/sec, and the %ADCs improved to 106.7% and 106.5% respectively. The lesions in the white matter of the right pre- and postcentral gyrus were reversible. The former was thought to be mainly ascribed to cellular edema and the latter was vasogenic edema. The present case showed when %ADC of the ischemic lesion in cerebral venous thrombosis was higher than 60%-70%, conservative therapy alone is sufficient effective for the improvement of neurological deficits.     

Recent progress in diagnostic imaging of cerebrovascular diseases]

The recent development of the neuroimaging modalities has enabled early detection of abnormal cerebral perfusion due to arterial steno-occlusive lesions by means of single photon emission computed tomography (SPECT) and perfusion weighted images of magnetic resonance imaging (MRI), early detection of ischemic brain damage by means of diffusion weighted image of MRI, and lacunar infarction and hemorrhage by means of T 2 * weighted images. These methods are now available for the clinical practice. The imaging technique further visualized various pathological states associated with cerebrovascular disease. The fiber tracts in the white matter and its disruption can be evaluated by anisotropy imaging of MRI. Selective neuronal necrosis after mild ischemia was detected by radioactive tracers specifically bound to neurons. These progress may contribute to uncover the pathophysiology of cerebrovascular diseases and to treat the patients.     

Detection of wallerian degeneration in a newborn by diffusion magnetic resonance imaging (MRI)

We present the case of an infant with hypoxic-ischemic encephalopathy in whom wallerian degeneration is demonstrated in white-matter fiber tracts by diffusion magnetic resonance imaging (MRI). MRI was undertaken on days 2 and 9 and then at 9 months of age. On day 2, conventional MRI was normal, but diffusion MRI showed bioccipital abnormalities. On day 9, diffusion MRI showed marked abnormalities in the deep white matter of the occipital regions (left > right), corpus callosum, left posterior limb of the internal capsule, and left cerebral peduncle. Water apparent diffusion coefficient values showed a significant reduction in the left occipital white matter and corpus callosum between days 2 and 9 while demonstrating the expected pseudonormalization in cortical gray matter. Images at 9 months showed left occipital porencephaly and atrophy of the left cerebral peduncle, with the infant displaying right hemiplegia at 18 months of age. In this case, the time course of diffusion changes differed between white and gray matter, with diffusion MRI showing delayed wallerian degeneration of the cerebral white matter. This case characterizes this degeneration with clinical and follow-up MRI at 9 months of age.     

Primary central nervous system lymphoma initially mimicking lymphomatosis cerebri: An autopsy case report

A 59‐year‐old immunocompetent man was admitted to our hospital because of progressive dementia with concomitant bilateral uveitis. The first brain MRI revealed diffuse hyperintense lesions in the cerebral white matter of both hemispheres on a T2‐weighted image and fluid‐attenuated inversion recovery image. However, another MRI taken more than 1 month later revealed enhanced cohesive mass lesions in the bilateral thalami, in addition to the white matter lesions. The white matter lesions were slightly hyperintense on a diffusion‐weighted image and apparent diffusion coefficient map image, suggesting vasogenic edema. One year after the onset of uveitis, he died of respiratory failure. Pathological diagnosis was diffuse large B‐cell lymphoma with perivascular proliferation and diffuse scattered infiltration in the cerebrum and brainstem. Microscopically, cohesive mass lesions in the bilateral thalami were a massive cluster of lymphoma cells. This is a case of primary CNS lymphoma (PCNSL) mimicking ‘lymphomatosis cerebri (LC)’ at first but later exhibiting typical mass lesions, giving rise to the possibility that cases of LC might unmask features of regular lymphomas in their later course more often than believed thus far.     

White matter changes following experimental pediatric traumatic brain injury: an advanced diffusion-weighted imaging investigation

Pediatric traumatic brain injury (pTBI) is a major community health concern. Due to ongoing maturation, injury to the brain at a young age can have devastating consequences in later life. However, how pTBI affects brain development, including white matter maturation, is still poorly understood. Here, we used advanced diffusion weighted imaging (DWI) to assess chronic white matter changes after experimental pTBI. Mice at post-natal day 21 sustained a TBI using the controlled cortical impact model and magnetic resonance imaging (MRI) was performed at 6 months post-injury using a 4.7 T Bruker scanner. Four diffusion shells with 81 directions and b-values of 1000, 3000, 5000, and 7000s/mm² were acquired and analyzed using MRtrix3 software. Advanced DWI metrics, including fiber density, fiber cross-section and a combined fiber density and cross-section measure, were investigated together with three track-weighted images (TWI): the average pathlength map, mean curvature and the track density image. These advanced metrics were compared to traditional diffusion tensor imaging (DTI) metrics which indicated that TBI injured mice had reduced fractional anisotropy and increased radial diffusivity in the white matter when compared to age-matched sham controls. Consistent with previous findings, fiber density and TWI metrics appeared to be more sensitive to white matter changes than DTI metrics, revealing widespread reductions in fiber density and TWI metrics in pTBI mice compared to sham controls. These results provide additional support for the use of advanced DWI metrics in assessing white matter degeneration following injury and highlight the chronic outcomes that can follow pTBI.

     

Cortical gray matter lesions in acute encephalopathy with febrile convulsive status epilepticus

In acute encephalopathy with febrile convulsive status epilepticus (AEFCSE), subcortical white matter lesions on diffusion-weighted images are sometimes encountered on magnetic resonance imaging (MRI), such as in acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). We report here a severe case of AEFCSE following respiratory syncytial virus infection, with emphasis on the cranial MRI findings. MRI in this patient showed widespread T2-hyperintensity along the cerebral cortical gray matter from day 3 to day 22. Lesions with reduced diffusion were noted on day 3 in the deep zone of gray matter of the left occipito–temporo–parietal cortex, but on day 7 they shifted to the subcortical white matter of both the cerebral hemispheres. These MRI findings provide radiologic evidence for damage to the cortical gray matter in AEFCSE. The serial change of diffusion-weighted images suggests that the cortical gray matter may be injured prior to the involvement of the subcortical white matter.     

MRI in 31 patients with Beh?et's disease and neurological involvement: prospective study with clinical correlation.

Thirty one patients with Behçet's disease and neurological manifestations were prospectively studied with MRI. Cerebral venous thrombosis was diagnosed in 10 patients. MRI performed during the acute illness in eight patients showed an abnormally high signal on the T2 weighted sequences in the occluded sinus. MRI showed minor flow abnormalities suggestive of partial recanalisation of the sinus in two cases at a later clinical stage. MRI can be an alternative, non-invasive, investigation to intravenous cerebral angiography. In 13 patients with central nervous system involvement, MRI performed during the acute illness showed multiple hyperintense lesions on T2 weighted sequences. They were usually less than 5 mm, scattered and confluent, mainly in the white matter, distributed in the hemispheric white matter in nine cases, brainstem in eight, basal ganglia and thalamus in five, and cortex in two. MRI abnormalities were usually associated with appropriate clinical deficits, but were larger and more disseminated than expected.     

Diffusion tensor imaging abnormalities in focal cortical dysplasia

PURPOSE: Focal cortical dysplasia (FCD) is one of the most common underlying pathologic substrates in patients with medically intractable epilepsy. While magnetic resonance imaging (MRI) evidence of FCD is an important predictor of good surgical outcome, conventional MRI is not sensitive enough to detect all lesions. Previous reports of diffusion tensor imaging (DTI) abnormalities in FCD suggest the potential of DTI in the detection of FCD. The purpose of this study was to study subcortical white matter underlying small lesions of FCD using DTI. METHODS: Five patients with medically intractable epilepsy and FCD were investigated. Diffusion tensor imaging images were acquired (20 contiguous 3 mm thick axial slices) with maps of fractional anisotropy (FA), trace apparent diffusion coefficient (trace/3 ADC), and principal eigenvalues (ADC parallel and ADC perpendicular to white matter tracts) being calculated for each slice. Region of interest analysis was used to compare subcortical white matter ipsilateral and contralateral to the lesion. RESULTS: Three subjects with FCD associated with underlying white matter hyperintensities on T2 weighted MRI were observed to have increased trace/3 ADC, reduced fractional anisotropy and increased perpendicular water diffusivity which was greater than the relative increase in the parallel diffusivity. No DTI abnormalities were identified in two patients with FCD without white matter hyperintensities on conventional T2-weighted MRI. CONCLUSIONS: While DTI abnormalities in FCD with obvious white matter involvement are consistent with micro-structural degradation of the underlying subcortical white matter, DTI changes were not identified in FCD lesions with normal appearing white matter.     

Comparative neuroimaging with pathologic correlates in Alexander's disease

We describe a case of pathologically confirmed Alexander's disease in which serial cranial ultrasound studies demonstrated unique findings of enlarging subependymal cysts with evolving periventricular hyperechogenicity. Computed tomographic scan of the head showed low attenuation of the periventricular white matter and centrum semiovale. Magnetic resonance imaging (MRI) demonstrated diffuse, confluent high signal predominantly in frontal white matter. These imaging modalities, particularly cranial ultrasound and MRI, may be useful tools in the diagnostic evaluation of children with degenerative neurologic disease, megalencephaly, and suspected Alexander's disease.     

Reversible posterior leukoencephalopathy syndrome in two patients with microscopic polyarteritis nodosa]

We report here two cases (72-year-old woman, 77-year-old-woman) with perinuclear anti-neutrophil antibody (P-ANCA) positive microscopic polyarteritis nodosa (mPN). Both patients presented with generalized convulsion, consciousness disturbance and severe hypertension several days after the administration of high dose methylpredonisolone followed by oral predonisolone. CT brain scan showed hypodensity area on bilateral posterior lobes. MRI T2 weighted image and FLAIR image showed increased signal intensity on the occipital gray and white matter. Although diffusion weighted MRI disclosed slightly high signal intensity, apparent diffusion coefficient (ADC) value at the occipital gray and white matter remained normal or even elevated. These findings, which were consistent with vasogenic edema, lead us to diagnose them as suffering from reversible posterior leukoencephalopathy syndrome (RPLS). After the second administration of high dose methylpredonisolone, their symptoms and signs, together with the MRI findings, gradually improved. To our knowledge, this is the first report concerning RPLS in a patient with mPN.     

Magnetic resonance imaging findings in a fatal case of Salmonella typhi-associated encephalopathy: a case report and literature review

We describe MRI findings in a fatal case of culture proven Salmonella typhi-associated encephalopathy. MRI findings included symmetrical diffuse abnormal signal in centrum semiovale, periventricular and deep white matter, splenium of corpus callosum and cerebellar deep white matter with central area of restricted diffusion. There was no contrast enhancement, significant edema or mass effect. Previous literature is also reviewed for imaging findings in Salmonella associated encephalopathy.     

颅脑MRI检查对Wernicke脑病的诊断价值

目的 探讨颅脑MRI检查对Wemicke脑病(WE)的诊断价值.方法 回顾性分析8例WE患者的临床资料及MRI检查结果.结果 8例WE患者MRI示脑部T2 WI、Flair成像及弥散加权成像(DWI)有对称性异常高信号影,其中出现在丘脑内侧6例、中脑导水管周围灰质4例、第三脑室周围灰质3例、乳头体2例及壳核、视交叉、小脑上蚓部、皮质下白质各1例;2例有增强效应.2例发病早期T2 WI、Flair无异常信号影,DWI示丘脑内侧对称性异常高信号影.结论 MRI对WE具有诊断价值,DWI对WE的早期诊断价值更高.     

海洛因海绵状白质脑病的影像学特征

目的　探讨海洛因海绵状白质脑病 (HSL E)的 CT、MRI和 PET特点。方法　对 2 9例患者的CT、MRI以及 4例患者的 PET资料进行分析。结果　 (1) CT和 MRI显示病变位于双侧小脑、内囊后肢、枕顶叶深部等部位白质 ,病灶广泛且对称 ;(2 ) CT示界限清楚的低密度病灶 ,MRI呈长 T1 WI、长 T2 WI异常信号 ,无水肿 ,快速反转恢复序列 (FL AIR)和增强扫描提示血脑屏障无破坏 ,PET显示为低代谢或无代谢病灶 ;(3)未治疗患者内囊后肢、枕叶和小脑白质无代谢 ,康复期患者代谢明显减低 ;(4 )临床症状改善者和未治疗者小脑皮质代谢降低 ,临床症状明显改善者代谢正常。结论　 HSL E患者的 CT和 MRI改变多局限于白质 ,极为相似。 PET显示病变部位低代谢或无代谢 ,小脑皮质和白质代谢的恢复对 HSL E患者的临床转归非常重要 ,故判断 HSL E患者的转归 ,PET较之 MRI更有价值     

Case of methotrexate encephalopathy: findings on diffusion tensor image and correlation with clinical outcome]

Methotrexate (MTX) is a major cause of treatment-related acute neurotoxicity. We report on clinical and imaging findings of reversibly restricted diffusion in a patient with transient encephalopathy after high dose MTX therapy for osteosarcoma. During the chemotherapy, a 19-year-old man was introduced for the evaluation of consciousness disturbance. Neurological examination revealed confusion, inability of speak at the onset On next day, there were still difficulties in swallowing and phonation, and furthermore deep tendon reflexes were hyperactive in bilateral lower limbs with positive Babinski responses bilaterally. By the 6th day, findings at neurological examination were completely normal. Initial imaging on presentation was performed using MRI. Diffusion weighted MRI clearly indicated areas of restricted diffusion within both centrum semiovale. These abnormalities were confirmed by the diffusion tensor (DT) technique (ADC and FA map). The follow-up MRI examinations using same protocol showed resolution of the ADC and FA abnormalities but increasing T2-signal changes. Neither contrast enhancement nor atrophy was encountered. Early detection of MTX white matter injury by DT image has the potential to alert the oncologist and neurologist to this event and provide a technique by which treatment of neurotoxicity can be monitored.     

Acute encephalopathy with biphasic seizures and late reduced diffusion with visual disturbance and higher brain dysfunction

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a recently described clinicoradiologic syndrome. Clinically, a prolonged febrile seizure is followed by subsequent seizures which occur several days after the initial seizure. On MRI, reduced diffusion appears predominantly in the frontoparietal subcortical white matter at the time of the subsequent seizures. The main symptom between the initial and subsequent seizures is disturbance of consciousness. We report a case with AESD who presented 1) reduced diffusion on MRI which was dominant in the occipital lobe, and 2) reversible visual disturbance followed by higher brain dysfunction such as a cognitive deficit and disturbed speech. A 2-year-old Japanese girl was admitted because of visual disturbance which appeared 4 days after a generalized tonic-clonic seizure associated with fever. Two days later, she had another seizure when MRI revealed reduced diffusion in the subcortical white matter. The MRI finding was not typical of AESD in that reduced diffusion appeared dominantly in the occipital lobe. Normal ophthalmologic findings and abnormal visual evoked potential results suggested that her visual disturbance was due to an impaired visual pathway in the subcortical white matter in the occipital lobe. The present case indicates that there is a subgroup of AESD in which the subcortical lesion seen on MRI is dominant in the occipital lobe.