Diagnostic usefulness of diffusion-weighted magnetic resonance imaging in influenza-associated acute encephalopathy or encephalitis

A magnetic resonance imaging (MRI) study was performed for a 20-month-old girl with an influenza type A infection who presented acute encephalopathy. Conventional MRI performed 8 days after the onset of encephalopathy, including T1-weighted, T2-weighted, and fluid-attenuated inversion recovery imaging, revealed only vague lesions in the right frontal, temporal, and parietal lobes. In contrast, diffusion-weighted imaging (DWI) then demonstrated the lesions much more intensively. On the 26th day, the lesions previously observed on DWI had become less discernible. The hyperintensity observed on DWI might reflect cytotoxic edema. Thus, DWI may be useful for evaluation of acute influenzal encephalopathy/encephalitis.     

Diffusion-weighted magnetic resonance imaging of neuro-Beh?et's disease]

We report 2 patients (35-year-old and 38-year-old men) with neuro-Beh?et's disease and characterize their diffusion-weighted MRI (DWI) findings of brain. T2-weighted and fluid-attenuated inversion recovery images obtained during the acute phase of neurological manifestations demonstrated multiple hyperintense lesions with a characteristic distribution in the brain including brainstem, thalamus, basal ganglia, and cerebral hemisphere. Most of these lesions did not exhibit increased signal intensity on DWI. This MRI profile, especially the combination of isointensity on DWI and hyperintensity on T2-weighted image, of neuro-Beh?et's disease is similar to that of multiple sclerosis, and different from that of acute cerebral infarction and herpes simplex encephalitis.     

MRI abnormalities associated with partial status epilepticus

OBJECTIVE: To report neuroimaging findings in patients with complex partial status epilepticus. BACKGROUND: During status epilepticus, neuroimaging may be used to exclude other neurologic conditions. Therefore, it is important to identify the neuroimaging features that are associated with status epilepticus. In addition, MRI characteristics may provide insight into the pathophysiologic changes during status epilepticus. METHODS: The history and neuroimaging examination results of three patients with complex partial status epilepticus were reviewed. Studies obtained during status epilepticus included diffusion-weighted MRI (DWI), MR angiography (MRA), postcontrast T1-weighted MRI, T2-weighted MRI, and CT. Follow-up MRI was obtained in two patients, and autopsy results were available for the third. RESULTS: Some of the MRI and CT findings during partial status epilepticus mimicked those of acute ischemic stroke: DWI and T2-weighted MRI showed cortical hyperintensity with a corresponding low apparent diffusion coefficient, and CT showed an area of decreased attenuation with effacement of sulci and loss of gray-white differentiation. However, the lesions did not respect vascular territories, there was increased signal of the ipsilateral middle cerebral artery on MRA, and leptomeningeal enhancement appeared on postcontrast MRI. On follow-up imaging, the abnormalities had resolved, but some cerebral atrophy was present. CONCLUSIONS: The radiologic characteristics of status epilepticus resemble those of ischemic stroke but can be differentiated based on lesion location and findings on MRA and postcontrast MRI. The MRI abnormalities indicated the presence of cytotoxic and vasogenic edema, hyperperfusion of the epileptic region, and alteration of the leptomeningeal blood-brain barrier. These changes reversed, but they resulted in some regional brain atrophy.     

Delayed ischemic hyperintensity on T1-weighted MRI in the caudoputamen and cerebral cortex of humans after spectacular shrinking deficit

BACKGROUND AND PURPOSE: Transient internal carotid artery (ICA)-middle cerebral artery (MCA) occlusion caused by cardiogenic embolus can lead to spectacular shrinking deficit (SSD): sudden hemispheric stroke syndrome followed by rapid improvement. The aim of this study was to investigate sequential neuroradiological changes in the brains of patients after SSD compared with those after brief cardiac arrest and hypoglycemia, which we previously studied with the same methods. METHODS: We serially studied CT scans and MR images obtained at 1.5 T in 4 patients with SSD. All 4 patients suffered from transient neurological deficits due to cardiogenic embolus in ICA-MCA. The symptoms began to disappear from 25 to 50 minutes after onset. RESULTS: Repeated CT scans demonstrated no abnormal findings in the affected cerebral hemisphere in 3 of the 4 patients and a small cortical infarct in the remaining 1. In each patient, repeated MRI between day 7 and month 23 after stroke showed basal ganglionic and cortical lesions. These lesions were hyperintense on T1-weighted and relatively hypointense on T2-weighted imaging. These ischemic lesions of hyperintensity on T1-weighted MRI subsided with time. CONCLUSIONS: Transient ICA-MCA occlusion leading to SSD produces a specific ischemic change with delayed onset in the basal ganglia and cerebral cortex in humans on MRI but not CT scans. We speculate that the lesions represent incomplete ischemic injury, including selective neuronal death, proliferation of glial cells, paramagnetic substance deposition, and/or lipid accumulation. Unlike brief cardiac arrest or hypoglycemia, the localized lesions on MRI of patients after SSD seem to be incomplete and to differ from infarction or hemorrhage.     

Disappearance of globus pallidus hyperintensity in a patient with portal-systemic encephalopathy after occlusion of the shunt vessel]

A 67-year-old woman was admitted to our hospital with confusion and asterixis on January 23, 1994. She had had the same symptoms repeatedly. On admission she was disorientated, and had slurred speech and asterixis. Laboratory data showed hyperammonemia (84 micrograms/dl) with a poor ICG hepatic clearance (ICG15min = 32%), although hepatic failure did not exist. Abdominal ultrasonography, CT scan and liver biopsy showed no evidence of cirrhosis. Celiac arteriography revealed a large shunt vessel connecting the portal vein to the left renal vein. A 1.5 T magnetic resonance imaging (MRI) demonstrated a bilateral and symmetrical hyperintensity of the globus pallidus in the T1-weighted images. Portal-systemic encephalopathy recurred repeatedly in spite of the conservative therapy, and there was no evidence of the portal hypertension. Therefore, the operative procedure of ligation of the shunt vessel was done on February 21, 1995. After the operation, blood ammonia level and ICG hepatic clearance were normalized. She became free from encephalopathy. Twenty-seven months after the operation, the hyperintensity of the globus pallidus in the T1-weighted images completely disappeared. There have been several reports describing that the globus pallidus alterations on the T1-weighted images in patients with liver cirrhosis, manganese intoxication and portal-systemic encephalopathy. To our knowledge, this is the first case that the hyperintense signal of the basal ganglia in a patient with portal-systemic encephalopathy disappeared completely after occlusion of the shunt vessel.     

海绵窦海绵状血管瘤的影像特点

目的 探讨海绵窦海绵状血管瘤(CSCH)的影像学特点.方法 回顾性分析17例经手术病理证实的CSCH的影像表现,其中男3例,女14例,平均47.4岁;均行MRI平扫及增强检查;8例行CT检查,其中3例加做CT增强扫描.结果 17例CSCH的影像表现如下:(1)常见于中年女性,呈"哑铃形"或"葫芦状",边缘清晰,有占位效应,很少出现瘤周水肿、瘤内出血及钙化.(2)T1WI呈低信号,T2WI呈高信号,信号均匀,增强后明显强化;T2WI高信号及出现延迟强化效应为其特征.(3)CT表现为高密度,明显强化.可有临近骨质的压迫性吸收,无骨质增生.(4)DSA显示血管正常或出现静脉期染色.结论 CSCH有比较典型的影像表现特点,结合临床病史,有助于术前诊断.     

Bilateral demyelinating tumefactive lesions in three children with hemiparesis

We present the results from the evaluations of three children ages of 2, 7, and 11 years with hemiparesis and multiple white-matter lesions on magnetic resonance images (MRIs). The initial symptoms were mainly acute/subacute hemiparesis in all and headache/vomiting in one of them. Before admission, one of them had a history of upper respiratory tract infection, whereas another had undergone urinary tract surgery, and the other reported no history of any infection or stress-related factor. In all of the children, MRI showed multiple superficial and deep white-matter hyperintensity in T2-weighted and proton density images with perifocal edema in the acute phase. During the symptomatic period, all of the patients underwent corticosteroid treatment. Whereas two of the patients demonstrated signs of recovery during the first week of treatment, the other patient demonstrated almost a full recovery with minimal neurologic sequela. Follow-up MRI demonstrated not only a remarkable decrease in the size and number of the lesions, with complete resolution for many of them, it also demonstrated a loss of contrast enhancement. None of these three patients, who had been followed up clinically and through MRI for 5 years, have shown either a clinical relapse or new lesions. The clinical pictures and MRI of the children were different in some aspects from acute multiple sclerosis and acute disseminated encephalomyelitis. Regarding both the clinical follow-up and treatment strategy, it is essential and interesting to state the fact that tumefactive lesions involving both hemispheres are likely to appear during the monitoring of the monophasic courses among inflammatory demyelinating diseases of childhood such as acute disseminated encephalomyelitis.     

Magnetic Resonance Imaging as a Sensitive and Specific Predictor of Neoplasms Removed for Intractable Epilepsy

Twenty-three patients had magnetic resonance imaging (MRI) and computed tomography (CT) of the head prior to surgery for medically intractable epilepsy. Eleven patients had neoplasms, mostly astrocytomas. Six of the 11 tumors were seen on CT. In five of the six cases, the MRI showed a focal area of increased signal on T2-weighted images. All 11 tumors were detected by MRI. None of the non-neoplastic lesions produced an abnormal T2-weighted signal area on MRI. Only one of the non-neoplastic lesions was seen on both CT and on MRI. MRI allowed clear discrimination between tumors and non-neoplastic lesions in patients coming to surgery for intractable epilepsy.     

Diffusion-weighted imaging in neonatal cerebral infarction: clinical utility and follow-up

We describe the clinical utility of echo-planar diffusion-weighted imaging in neonatal cerebral infarction. Eight full-term neonates aged 1 to 8 days referred for neonatal seizures were studied. Patients were followed for a mean of 17 months with detailed neurologic examinations at regular intervals. Head computed tomography (CT) and conventional magnetic resonance (MRI) and diffusion-weighted images were obtained. Percent lesion contrast was evaluated for 19 lesions on T2-weighted and diffusion-weighted images. Follow-up conventional MRIs were obtained in seven patients. The findings on diffusion-weighted imaging were correlated with CT and conventional MRI findings as well as with short-term neurodevelopmental outcome. Four patients had focal cerebral infarctions. Four patients had diffuse injury consistent with hypoxic-ischemic encephalopathy. Percent lesion contrast of all 19 lesions was significantly higher on diffusion-weighted images when compared with T2-weighted images. In five patients, there were lesions visualized only with diffusion-weighted imaging. In all patients, there was increased lesion conspicuity and better definition of lesion extent on the diffusion-weighted images compared with the CT and T2-weighted MR images. In seven of eight patients follow-up imaging confirmed prior infarctions. Short-term neurologic outcome correlated with the extent of injury seen on the initial diffusion-weighted imaging scans for all patients. Diffusion-weighted imaging is useful in the evaluation of acute ischemic brain injury and seizure etiology in neonates. In the acute setting, diffusion-weighted imaging provides information not available on CT and conventional MRI. This information correlates with short-term clinical outcome.     

Neuroradiological studies of Wilson's disease by computed tomography and magnetic resonance imaging

Three cases of Wilson's disease were imaged by computed tomography and magnetic resonance. They were characterized by common findings. CT scan showed atrophy of cerebral cortex, caudate head, midbrain and cerebellum, and areas of low absorption in the caudate head, putamen, globus pallidus, posterior limb of internal capsule, thalamus and midbrain. The T2-weighted MRI imaging demonstrated marked hyperintensity in the putamen, retrolenticular part of internal capsule, thalamus and midbrain. In 2 patients, these high intensity areas were decreased by chelating therapy. Improvement of the increased intensity on T2-weighted images led to the suggestion that the area of marked hyperintensity area might be edema or demyelination rather than neuronal loss or cavitation.     

Magnetic Resonance Reflects the Pathological Evolution of Wernicke Encephalopathy

BACKGROUND AND PURPOSE: Wernicke encephalopathy (WE) is an acute phase of Wernicke-Korsakoff syndrome. Pathologic findings change between acute and chronic phases. Only a few magnetic resonance imaging (MRI) studies have been done to date. METHODS: To correlate the MRI findings in acute and chronic stages of WE with the known pathologic information, 15 consecutive patients with WE were examined with MRI: 3 before thiamine treatment, 7 within 24 hours of thiamine treatment, 4 between the second and sixth day after thiamine treatment, and 1 fifty-five days after thiamine treatment. Nine of the patients had follow-up MRI between 2 days and 33 months. T1-weighted, proton, and T2-weighted axial images were obtained with additional 5-mm-thick T1-weighted sagittal and coronal images to better visualize the mammillary bodies. RESULTS: In the acute WE, MRI showed high signal intensityon T2-weighted images in periaqueduct and medial thalamic regions. In a few patients with alcoholism, vermian and mammillary body atrophies and third ventricular enlargements were noted. In the chronic phase of WE, T2 hyperintensity disappeared but mammillary bodies and cerebellar vermis became atrophic and third ventricular enlargements were evident. High signal intensity on T2-weighted images disappeared as early as 2 days, and atrophic changes appeared as early as 1 week. CONCLUSION: MRI is useful for in vivo monitoring and reflects the pathological evolution in acute and chronic phases of WE.     

DWI及MRA在大面积脑梗塞早期诊断中的价值

目的:评价弥散加权磁共振成像DWI和磁共振血管成像MRA对早期大面积脑梗塞的诊断价值。方法:对24例早期大面积脑梗塞的临床和磁共振资料进行分析,全部患者均行DWI及MRA检查。结果:24例早期大面积脑梗塞中,13例急性期CT扫描未检测出确切病灶,DWI扫描全部出现大片异常高信号,病灶检出率为100％。而在常规T2WI检查中,7例为阴性,病灶检出率为69％。MRA发现血管异常24例,表现为供血动脉闭塞,狭窄、硬化。结论: DWI有助于明确早期大面积脑梗塞病变范围,且能区别新旧病灶。MRA能直接显示大面积脑梗塞闭塞的供血脑血管,联合使用DWI和MRA对早期大面积脑梗塞诊断有重要的临床价值,也有利于早期合理的治疗方案制定及预后判断。     

Brain magnetic resonance image changes in a family with congenital and classic myotonic dystrophy

We present the clinical manifestations, brain magnetic resonance images (MRI), and genetic analysis of a family with 2 siblings with congenital myotonic dystrophy type 1 (DM1) and 4 patients with classic DM1. These 2 patients with congenital DM1 had severe mental retardation and a characteristic feature of hyperintensity of white matter at the posterior-superior trigone (HWMPST), in addition to ventricular dilatation in T2-weighted images (T2WI) of brain MRI. In 2 of the 4 classic DM1 patients, brain T2WI MRI showed hyperintensity lesions in the bilateral frontal and/or temporal regions, which were absent in congenital DM1. In conclusion, we suggest that the HWMPST in brain MRI is a characteristic finding in congenital DM1, and that the severe cognitive impairments are not only attributable to the subcortical white matter lesions. In congenital DM1, the cognitive function is a diffuse impairment, which is different from that in classic DM1.     

MRI characteristics of the MLF in MS patients with chronic internuclear ophthalmoparesis

OBJECTIVE: The authors imaged the medial longitudinal fasciculus (MLF) in 58 patients with MS and chronic internuclear ophthalmoparesis (INO) to determine which MRI technique best shows the characteristic lesion associated with this ocular motor syndrome. METHODS: Using quantitative infrared oculography, the authors determined the ratios of abduction to adduction for velocity and acceleration, to confirm the presence of INO and to determine the severity of MLF dysfunction in 58 patients with MS and INO. Conventional MRI techniques, including proton density imaging (PDI), T2-weighted imaging, and fluid-attenuated inversion recovery (FLAIR) imaging, were used to ascertain which technique best shows MLF lesions within the brainstem tegmentum. T1-weighted imaging was performed to determine the frequency of brainstem tegmentum hypointensities. RESULTS: All patients studied had evidence of an MLF lesion hyperintensity on PDI, whereas T2-weighted imaging and FLAIR imaging showed these lesions in 88% and 48% of patients, respectively. With PDI, dorsomedial tegmentum lesions were seen in the pons in 93% of patients and in the midbrain of 66% of patients. Lesions were observed at both locations in 59% of patients. One patient had an MLF lesion with a corresponding T1 hypointensity. CONCLUSIONS: PDI best shows the MLF lesion in patients with MS and INO.     

Comparison of MRI white matter changes with neuropsychologic impairment in Cockayne syndrome.

The neuropsychologic function and white matter changes observed on magnetic resonance imaging (MRI) in Cockayne syndrome were studied. MRI with T2-weighted sequences revealed periventricular hyperintensity and white matter hyperintensity in all 3 Cockayne syndrome patients examined; in contrast, 8 age-matched controls had no periventricular or white matter hyperintensity. MRI scans were graded according to the severity of periventricular or white matter hyperintensity using a scale applied to an elderly patient population. There was no difference in the severity of MRI white matter changes in these 3 Cockayne syndrome patients, 2 of whom had severe neuropsychologic functions and one a relatively milder one. There was no correlation between neuropsychologic impairment and MRI white matter changes.     

MRI demonstration and CT correlation of the brain in patients with idiopathic intracerebral calcification

Twenty-two patients aged 36–63 years were diagnosed as having Fahr's syndrome on the basis of the presence on CT of unexpected extensive calcification of the basal ganglia. Even when associated with calcification of other brain areas, the main diagnostic criterion remained basal ganglia calcification larger than 800 mm². Normal values of parathormone, serum calcium and phosphorus excluded hypercalcaemia and hypoparathyroidism. Mitochondrial CNS disease was excluded clinically. MRI and repeated CT and neurological examination were performed in all of the patients. The patients were divided into two groups: neurologically asymptomatic (group 1) and neurologically symptomatic (group 2). T2-weighted sequences demonstrated hyperintense areas in all of the patients involving the white and the grey matter of the brain. In group 1 the hyperintense lesions were significantly smaller than in group 2. The neurological symptoms correlated better with the hyperintensities on T2-weighted MR images than with the calcification demonstrated on CT. Hyperintensities in T2-weighted MRI and the areas shown by CT to have calcification had different locations. In 15 patients with dementia, the white matter of the entire centrum semiovale was bilaterally hyperintense. In another 3 patients with hemiparesis, hyperintense areas in the internal capsule, contralateral to the side of hemiparesis, were demonstrated in the T2-weighted sequence. The hyperintense T2 signals may reflect a slowly progressive, metabolic or inflammatory process in the brain which subsequently calcifies and are probably responsible for the neurological deficit observed.     

Magnetic Resonance Imaging in Complex Partial Seizures

Abstract: Magnetic resonance imaging (MRI) and computed tomography (CT) were performed on 45 patients with intractable complex partial seizures. MRI was performed with a super conducting whole-body scanner operating at 0.5 tesla (T) and 1.5 T. In patients with temporal lobe epilepsy, 8 of 24 patients had abnormal CT, but 16 of 24 patients showed abnormal MRI. 1.5 T MRI detected more abnormality than 0.5 T MRI when CT was normal. In patients with frontal lobe epilepsy, 5 of 7 patients had normal CT and MRI. In 2 other patients, MRI demonstrated an arachnoid cyst and increased signal intensity area on the T2-weighted images, which were not detected by CT. In patients with occipital lobe epilepsy, 5 of 6 patients show abnormal CT and MRI. In patients with tuberous sclerosis, MRI revealed some increased signal intensity areas on the T2-weighted images in the occipital and temporal lobe, which were not detected by CT. Most surface EEG foci corresponded with the side of MRI abnormality. These data indicate that MRI is more informative than CT in complex partial seizures. MRI is the imaging technique of choice in the diagnosis of complex partial seizures.     

Magnetic resonance imaging in complex partial seizures

Magnetic resonance imaging (MRI) and computed tomography (CT) were performed on 45 patients with intractable complex partial seizures. MRI was performed with a superconducting whole-body scanner operating at 0.5 tesla (T) and 1.5 T. In patients with temporal lobe epilepsy, 8 of 24 patients had abnormal CT, but 16 of 24 patients showed abnormal MRI. 1.5 T MRI detected more abnormality than 0.5 T MRI when CT was normal. In patients with frontal lobe epilepsy, 5 of 7 patients had normal CT and MRI. In 2 other patients, MRI demonstrated an arachnoid cyst and increased signal intensity area on the T2-weighted images which were not detected by CT. In patients with occipital lobe epilepsy, 5 of 6 patients show abnormal CT and MRI. In patients with tuberous sclerosis, MRI revealed some increased signal intensity areas on the T2-weighted images in the occipital and temporal lobe, which were not detected by CT. Most surface EEG foci corresponded with the side of MRI abnormality. These data indicate that MRI is more informative than CT in complex partial seizures. MRI is the imaging technique of choice in the diagnosis of complex partial seizures.     

MRI in neurosarcoidosis.

Nine patients with neurological manifestations of sarcoidosis were explored by MRI and, in some cases, CT. The MRI examinations were performed in T1- and T2-weighted spin-echo sequences in all patients, with gadolinium injection in seven. Several non-specific lesions were demonstrated, the most frequent of them showing on T2-weighted sequences as high-intensity signals in the periventricular white matter and the semi-oval centres. Other abnormalities, such as infiltrations of the hypothalamo-pituitary region, granulomatous masses within the brain tissue and meningeal infiltrations, were observed. These findings were in agreement with those found in the literature. Gadolinium injection seems to be important in this pathology, as it demonstrates lesions that are not visible on conventional T1- and T2-weighted spin-echo sequences.     

Arachnoid granulations in the transverse sinuses of a patient with ocular melanoma.

Arachnoid granulations show typical imaging features that allow their distinction from dural sinus thrombosis and intrasinus tumor. These features include a mid-lateral transverse sinus location, focality, common adjacent entering superficial veins, origin of attachment, low density on computed tomography (CT), isointensity-hypointensity on T1-weighted magnetic resonance imaging (MRI) and hyperintensity on T2-weighted MRI. We report the CT and MRI findings of incidentally detected bilateral arachnoid granulations in the transverse sinuses of a patient with ocular melanoma.