Nuclear magnetic resonance (NMR) imaging in Wilson disease

Nuclear magnetic resonance (NMR) scans of the head and liver were obtained in 13 patients with Wilson disease, and the results were compared with computed tomography (CT). Twelve age and sex matched normal controls were also scanned with NMR. The subjects were scanned using repeated free induction decay (RFID), inversion-recovery (IR), and spin-echo (SE) sequences. The IR scans of the brain provided excellent anatomical localisation while SE scans highlighted pathological areas. Within the brain, NMR demonstrated abnormalities in two patients with normal CT scans. More extensive involvement was shown with NMR in three additional cases. In the liver, NMR and CT showed similar abnormalities of morphology. T1 values were within the normal range in all cases, including three patients with high liver copper levels at the time of NMR examination.     

Magnetic resonance images of tuberous sclerosis

Summary The cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR=1800, TE=120) images and inversion recovery (TR=2100, TI=500–600, TE=40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter. Some of the parenchymal calcifications other than periventricular nodules showed identical MR signal intensities to periventricular nodules, and the rest of the parenchymal calcifications had similar intensities to the subcortical lesions. This indicates that parenchymal calcifications can occur in the demyelinating white matter as well as in the heterotopic tubers in the white matter. The severely mentally retarded patients tended to have a higher number of subcortical lesions and no correlation was noted between the severity of mental retardation and either the number of periventricular nocules or ventricular dilatation.     

Efficacy of contrast medium use for neuroimaging at 3.0 T: utility of IR-FSE compared to other T1-weighted pulse sequences

As inversion-recovery (IR) technique improves T1 contrast at high field strength, signal enhancement by T1-shortening contrast media may be affected. To clarify the different enhancement properties at 3.0 T, the authors compared T1-weighted sequences. Twelve contrast-enhancing lesions were investigated by spin-echo (SE), inversion recovery fast spin-echo (IR-FSE), two-dimensional gradient-echo (2D GE), and magnetization-prepared three-dimensional gradient-echo (3D GE) sequences and evaluated by comparing signal-intensity enhancements within the lesions. In addition, signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were measured. On average, signal enhancement of the lesions amounted to 60% for SE, 57% for IR-FSE, 32% for 2D GE, and 35% for 3D GE images. CNR of gray matter versus white matter was significantly higher for IR SE and GE imaging than for genuine SE and 2D GE acquisitions (Wilcoxon test), while 2D GE imaging alone had an excellent SNR. As IR-FSE images provide an excellent CNR for gray and white matter in the brain and contrast enhancement performs almost similarly well compared with SE imaging, this technique appears to be well suited for T1-weighted neuroimaging without and with contrast enhancement at 3.0 T. However, the inherent blurring of the IR-FSE can lead to poor performance for very small lesions.     

Temporal-lobe epilepsy: comparison of CT and MR imaging

In 50 patients with temporal-lobe epilepsy, CT and MR findings were compared. Axial CT scans were obtained before and after administration of contrast material. Coronal MR imaging was carried out with two spin-echo (SE) sequences with a repetition time of 1600 msec and echo times of 35 or 70 msec (SE 1600/35, SE 1600/70). A focal lesion was detected by CT in 12 cases and by MR in 16 cases. If discrete attenuation or signal abnormalities are also taken into account, CT provided a positive finding in 13 cases and MR imaging in 20 cases. With the exception of a small calcification, all the lesions revealed on the CT scans were also detected on the MR images. Among the examinations assessable for temporal-lobe asymmetry, signs of a unilateral reduction in temporal-lobe size were seen on two of 35 CT scans and on 15 of 38 MR images. In three patients who had temporal-lobe resection, a subsequent comparison was made between CT, MR imaging, and pathology. Histologically proven glial reactions that could not be detected on CT were demonstrated as high-signal-intensity lesions on the SE 1600/70 image. We conclude that MR scanning, with its higher sensitivity, superior image quality, and ability of multiplanar imaging, should be the imaging technique of choice in the diagnosis of temporal-lobe epilepsy.     

Potential for increasing conspicuity of short-T1 lesions in the brain using magnetisation transfer imaging

We investigated the feasibility of using T1-weighted magnetisation transfer sequences to generate tissue contrast and increase the conspicuity of short-T1 areas within the brain. We imaged two normal volunteers with and without saturating off-resonance radiofrequency irradiation at a range of repetition times (TR 200–760 ms). T1 values and magnetisation transfer ratios for white matter and deep grey matter were calculated. We studied eight patients with intracranial lesions showing short-T1 areas, using mildly T1-weighted sequences with and without magnetisation transfer contrast. Lesion numbers, areas and signal intensities were measured and lesion-to-background contrast was calculated. Comparison was made with conventional T1-weighted spin-echo images. In the normal volunteers, contrast between the thalamus, caudate and lentiform nuclei and white matter showed striking visual differences, with magnetisation transfer weighting, with decreasing TR. In all patients, short-T1 lesions were seen more clearly on magnetisation transfer-weighted images, with significant increase in lesion number, area and contrast, when compared with conventional T1-weighted scans.     

CT, MR, and pathology in HIV encephalitis and meningitis

The value and limitations of CT and MR in human immunodeficiency virus (HIV) infection of the brain was determined by a retrospective analysis of the CT scans (22) and MR images (7) in 22 patients with pathologically proved HIV encephalitis (21) or meningitis (1). Our clinical-radiologic-pathologic correlation suggested that, especially in the early stages of the disease, CT and MR were relatively insensitive in detecting the primary changes of HIV encephalitis. The multiple bilateral diffuse microscopic glial nodules with multinucleated giant cells of HIV found at autopsy in both gray and white matter were usually not directly visualized by either CT or MR. Secondary, nonspecific changes, however, were seen. These included cortical atrophy, found in virtually all patients with HIV encephalitis, and HIV-induced foci of demyelination found in the minority of cases. On CT the latter were seen in the white matter as nonenhancing, nonmass-producing areas of low density; on MR they were seen as frequently progressive high-intensity signal abnormalities on T2-weighted images, usually in the periventricular white matter and centrum semiovale. MR was more sensitive in detecting these demyelinative lesions than was CT. The clinical diagnosis of HIV encephalitis usually antedated the radiographic diagnosis. In HIV meningitis, contrast CT was more definitive than MR, showing striking enhancement of the subarachnoid spaces, although MR was more sensitive in detecting the secondary parenchymal changes.     

Brain radiation lesions: MR imaging

This retrospective study was performed to assess the capability of magnetic resonance (MR) to depict and characterize diffuse and focal radiation lesions in the brain using the spin-echo technique. The MR images of 55 patients who had undergone radiation therapy were reviewed. Comparative computed tomography (CT) studies were available for all the patients. Normal white matter was chosen as reference tissue for the quantitative comparison of signal intensities. Radiation lesions (identified in eight patients) were seen as regions of high signal intensity on the sequence with a long repetition time (TR) (2.0 sec) and showed no difference in signal compared with white matter when the TR was short (0.5 sec). Nonspecific prolongation of T1 and T2 relaxation times was measured in such lesions. In one patient, subependymal tumor spread, demonstrated by contrast-enhanced CT, was missed on MR images, masked by the adjacent abnormal signal owing to radiation effects. Recurrent or residual brain tumor could not be distinguished from radiation brain necrosis either by CT or by MR imaging. It is concluded that MR can depict radiation lesions with great sensitivity but is not very helpful for discrimination between recurrent or residual brain tumor, radiation necrosis, and other brain lesions.     

Encephalopathy in AIDS patients: evaluation with MR imaging

The presence and extent of encephalopathy were evaluated in 47 patients with AIDS or AIDS-related complex (ARC) by the use of MR imaging. Twenty-nine (62%) of the patients showed some form of white matter disease, exhibited as high signal intensity on T2-weighted images. Focal white matter lesions were seen in 23 (49%) of the patients, while a diffuse white matter process was observed in six patients (13%). Of the 29 patients who had white matter disease on MR scans, 17 (36%) had a suggestion of white matter involvement on an initial CT study. Meanwhile, 12 (26%) of the patients had a normal CT scan on the initial examination. MR findings showed predominant disease in the subinsular and peritrigonal white matter areas. Marked cerebral atrophy was observed in 17 (36%) of 47 patients, cerebellar atrophy in 18 (38%), and brainstem atrophy in seven patients (15%). Pathologic findings showed that toxoplasmosis was present in eight patients (17%), and primary CNS lymphoma was present in three patients (6%). Cryptococcal meningitis was noted in two (4%) of the patients at autopsy, and Mycobacterium tuberculosis was seen in one (2%) of the patients at autopsy. MR imaging has been shown to be a valuable technique for the detection of encephalopathy in AIDS patients.     

Usefulness and limitations of neuroradiologic tests (CT, US, MRI) in periventricular leukomalacia

Sixteen young patients, with clinical and radiological signs of periventricular leukomalacia (PVL), were investigated with MR imaging. Twelve of them were investigated with US in the perinatal period. The extant 4 patients, older than the others, had a clinical history of PVL. US scans were capable of yielding precise information about the anatomical features of PVL in both the acute and the middle phases. The lesions appeared as hyperechoic areas which subsequently turned to anechoic cavities. MR imaging and CT scans did not present any particular advantage over US scans in the acute phase, but they did detect periventricular damage when the patient was 6-7 months old. MR imaging was superior to CT in detecting the delayed myelination of white matter. Inversion-recovery sequences gave more anatomical details to distinguish normal from abnormal white matter. Spin-echo proton-density images detected periventricular gliosis, which appeared as persistent hyperintense areas. CT might be useful in the acute phase, after US detection of hyperechoic intraparenchymal areas, for it allowed purely ischemic lesions to be distinguished from hemorrhagic ones.     

Neonatal herpes simplex encephalitis: correlation of clinical and CT findings

Review of 31 computed tomographic (CT) scans in 15 neonates with herpes simplex encephalitis (HSE) type 2 revealed the most characteristic early findings to be patchy and widespread areas of low attenuation, primarily in white matter, with minimal contrast material enhancement in a meningeal pattern. The low-attenuation lesions increased rapidly in size and prominence during the course of the disease. This was usually accompanied by increased attenuation of cortical gray matter that persisted for weeks to months. Atrophic changes appeared rapidly, being evident in the 3d week. Late findings consisted of very extensive, diffuse, low attenuation of white matter with cortical atrophy. Calcification assumed a variety of distributions, from punctate to an extensive gyral pattern. The cerebellum was involved in nine patients. Early CT findings were not good predictors of outcome, but later serial CT scans showing progression or stability of findings were more accurate in prognosis. CT serves primarily to confirm the diagnosis of neonatal HSE.     

Cranial MRI in Wilson's disease

Summary Thirty-eight patients with biochemically proven Wilson's disease underwent magnetic resonanceimaging (MRI) of the brain as well as neurological examinations. The patients were scanned using spin-echo (SE) sequences; the neurologist was looking for typical symptoms: dysarthria, tremor, ataxia, rigidity/bradykinesia and chorea/dystonia. Pathological MR findings believed secondary to this uncommon inherited disorder of copper metabolism were found in twenty-two subjects. Focal abnormalities were seen in the lenticular, thalamic and caudate nuclei as well as in brain stem and white matter; these lesions were best demonstrated on T2-weighted sequences as hyperintense areas. In eight patients we found diffuse brain atrophy with consecutive widening of the ventricular system. Five subjects showed mild, nineteen severe neurologic deficits. Generally there was no correlation between MR findings and clinical neurological symptoms; the impairment of cell-metabolism causing functional alterations of the brain precedes morphological changes. During treatment with the copper chelator D-penicillamine there seemed to be a phased course of disease. Shortening of T1-relaxation due to paramagnetic influence of copper was not seen; a possible explanation could be intracellular deposition — a proton-electron-dipolar-dipolar-interaction would therefor be impossible.     

Preliminary experience of magnetic resonance imaging in neurosarcoidosis

Summary Twelve MR scans performed on seven patients with neurosarcoidosis are presented. The most common abnormalities were ventricular enlargement (four patients) and diffuse periventricular white matter changes (three patients). Infarcts were seen in three patients and mass lesion in one. The lesions were seen in both T1 and T2 weighted images. The results are compared with CT findings. MRI seems to be more sensitive than CT in detecting white matter changes and infarcts. Ventricular enlargement and granulomas were equally well seen with both modalities.     

White matter lesion contrast in fast spin-echo fluid-attenuated inversion recovery imaging: effect of varying effective echo time and echo train length.

OBJECTIVE: Our aim was to determine whether the contrast between white matter lesions and normal-appearing white matter in fast spin-echo fluid-attenuated inversion recovery (FLAIR) images can be improved by lengthening the effective TE and the echo train length. SUBJECTS AND METHODS: Thirty patients with various white matter lesions were imaged using fast spin-echo FLAIR sequences (TR = 10,002 msec; inversion time = 2200) on a 1.5-T MR imaging system. For 14 patients, fast spin-echo FLAIR sequences with a TE of 165 msec and echo train length of 32 (fast spin-echo FLAIR 165/32) were compared with fast spin-echo FLAIR sequences with a TE of 125 msec and echo train length of 24 (fast spin-echo FLAIR 125/24). For 16 other patients, fast spin-echo FLAIR 165/32 sequences were compared with fast spin-echo FLAIR sequences with a TE of 145 msec and echo train length of 28 (fast spin-echo FLAIR 145/28). Signal difference-to-noise ratios were calculated between the lesions and normal-appearing white matter for a typical lesion in each patient. RESULTS: In both groups, a small but statistically significant increase in the signal difference-to-noise ratio was found on the fast spin-echo FLAIR sequences using the longer TE and echo train length. In the first group, signal difference-to-noise ratio increased from 18.7 +/- 4.7 (mean +/- SD) for fast spin-echo FLAIR 125/24 to 20.1 +/- 4.5 for fast spin-echo FLAIR 165/32 (p < .05). In the second group, the signal difference-to-noise ratio increased from 15.4 +/- 4.0 for fast spin-echo FLAIR 145/28 to 16.8 +/- 4.6 for fast spin-echo FLAIR 165/32 (p <.01). In addition, fast spin-echo FLAIR sequences with a longer TE and echo train length were obtained more rapidly (6 min for fast spin-echo FLAIR 125/24, 5 min 20 sec for fast spin-echo FLAIR 145/28, and 4 min 41 sec for fast spin-echo FLAIR 165/32). CONCLUSION: Lengthening the TE to 165 msec and echo train length to 32 in fast spin-echo FLAIR imaging allows both a mild improvement in the contrast between white matter lesions and normal-appearing white matter and shorter imaging times.     

Cerebral sparganosis: CT characteristics

Cerebral sparganosis is an extremely rare parasitic zoonosis caused by a migrating plerocercoid tapeworm larva, genus Spirometra. Nineteen computed tomography (CT) scans of 12 patients with cerebral sparganosis were retrospectively analyzed and correlated with clinical and pathologic data. On CT scans, the following characteristics were noted: (a) unilateral involvement; (b) extensive or multifocal areas of low density along white matter bundles, with ipsilateral ventricular dilatation and localized cortical atrophy; (c) nodular or irregular enhancement with spotty calcification; and (d) change in location of enhancing nodules on sequential scans. These pathognomonic features reflect a chronic inflammatory process with both active granulomatous lesions and widespread degeneration of brain tissue, especially in the white matter. Degeneration is probably caused by migration of the long-surviving larva along the fiber tracts of white matter.     

Inversion-recovery echo-planar MR in adult brain neoplasia.

PURPOSEA T1-weighted multishot inversion-recovery (IR) echo-planar MR imaging (EPI) sequence was developed to improve intracranial tissue differentiation; its diagnostic utility was compared with that of conventional axial T1-weighted spin-echo and axial T2-weighted turbo spin-echo sequences.METHODSEighteen patients with known or suspected primary or metastatic brain neoplasia were imaged in a 1.5-T unit with IR-EPI sequences. Three observers measured gray/white matter contrast-to-noise ratios and subjectively compared IR-EPI sequences with T1-weighted spin-echo and T2-weighted turbo spin-echo sequences for gray/white matter discrimination, visibility of intracranial and vascular structures, overall lesion conspicuity, size of lesion(s), and presence and severity of artifacts.RESULTSTwenty-four lesions (including neoplasia, infarction, treatment-associated encephalomalacia, nonneoplastic white matter signal abnormalities, and basilar artery dolichoectasia) were detected in 12 patients. Basilar artery dolichoectasia was not included in subsequent statistical analysis. Pulsatile flow artifacts were markedly reduced on IR-EPI sequences relative to those on T1-weighted spin-echo sequences. Gray/white matter contrast was greater on IR-EPI images than on T1-weighted spin-echo images. Periaqueductal gray matter, basal ganglia, optic tracts, cranial nerve V, and claustrum were seen better or as well on IR-EPI images as compared with T1-weighted spin-echo images. IR-EPI was more sensitive to magnetic sensitivity effects, with resultant decreased visibility of cranial nerves VII and VIII and the orbital portion of the optic nerves. For noncontrast sequences, lesion conspicuity was better on IR-EPI images than on T1-weighted spin-echo images in 16 (70%) of 23 lesions and was equal on the two sequences in seven (30%) of 23 lesions. Lesion size, including surrounding edema, was greater on IR-EPI images than on T2-weighted turbo spin-echo images in two (9%) of 23 cases and equal in 21 (91%) of 23 cases. Hyperintense foci of methemoglobin were more conspicuous on T1-weighted spin-echo images.CONCLUSIONMultishot IR-EPI is superior to conventional T1-weighted spin-echo imaging for parenchymal tissue contrast and lesion conspicuity, and is equal to T2-weighted turbo spin-echo imaging in sensitivity to pathologic entities.     

新生儿和婴儿期Sturge-Weber综合征的CT诊断

目的:探讨新生儿和婴儿期Sturge-Weber综合征的CT表现。方法:回顾性分析1例新生儿期和7例婴儿期Sturge-Weber综合征患儿的临床和CT资料,均行常规CT平扫,其中5例同时行增强CT。结果:8例均有面部三叉神经分布区皮肤血管瘤,4例患儿出现患侧皮层钙化,4例未出现皮层钙化的患儿显示受累脑实质密度略增高,伴灰白质分界不清。8例患儿均表现为局部脑外间隙增宽及脑沟增宽等脑萎缩样改变,3例随访患儿出现脑萎缩。5例行增强扫描的患儿出现脑回样强化,4例患侧的侧脑室脉络丛增大,1例双侧Sturge-Weber综合征于10个月随访时出现双侧脉络丛增大。结论:CT对新生儿和婴儿期Sturge-Weber综合征的诊断有重要价值。     

MR imaging of periventricular leukomalacia in childhood

Eight children with clinical and radiologic abnormalities consistent with periventricular leukomalacia were investigated with MR imaging of the brain that employed both inversion-recovery and T2-weighted spin-echo imaging sequences. The more precise delineation of white and gray matter on inversion-recovery images as compared with CT allows a detailed demonstration of the anatomic features of periventricular leukomalacia; specifically, a reduced quantity of white matter in the periventricular region and centrum semiovale and, in more severe cases, cavitated infarcts that replace the immediate periventricular white matter. The T2-weighted spin-echo and short inversion time inversion-recovery images demonstrated abnormally increased signal in white matter that appeared normal on CT scans and only minimally abnormal on conventional inversion-recovery images. These abnormalities most probably represent white matter gliosis that extends beyond the immediate periventricular regions. MR recognition of cerebral white matter abnormalities associated with periventricular leukomalacia may confirm the clinical suspicion of this diagnosis in children with spastic diplegia or quadriplegia.     

脑灰质异位症MRI诊断

目的探讨脑灰质异位症(GMH)的MR I诊断及鉴别诊断。方法10例GMH患者均行MR回波序列扫描,其中男7例,女3例,年龄7~32岁,平均15岁。1例行MR增强扫描。结果10例共发现病灶14个,分为3种类型:室管膜下型5例、皮质下型3例、带状型2例。表现为侧脑室旁或白质区内的结节状或不规则状团块影,与大脑皮层灰质及灰质核团信号一致,单发7例、多发3例,单侧发病8例,双侧发病2例,大小1~5 cm不等,无水肿及占位效应,2例带状型灰质异位对称分布于皮层灰质与侧脑室间,内外均有白质带,与灰质信号一致。结论GMH的MR I表现具有特异性。     

Clinical usefulness of contrast-enhanced MP-RAGE of the brain

Our purpose was to evaluate the usefulness of a 3D T1-weighted gradient-echo sequence (MP-RAGE) in clinical practice. We prospectively examined 200 patients with a variety of neurological disorders and symptoms. We compared lesion conspicuity and contrast enhancement on MP-RAGE images with conventional gadolinium-enhanced spin-echo (SE) T1-weighted images. Both the original MP-RAGE data and the reformatted images were characterised by improved differentiation between grey and white matter. More lesions were found on the 3D series, in both patients with neoplastic and nonneoplastic disease. Contrast enhancement of small oedematous lesions affecting the white matter in demyelinating disease was less obvious. Multiplanar reformatting, which can be realised in any desired plane and surface rendering with sophisticated segmentation algorithms superbly displayed the underlying anatomical relationships between lesions and normal brain structures. Excellent spatial resolution, the absence of posterior fossa artefacts and equivalent contrast enhancement resulted in an increased number of space-occupying lesions being found on the MPRAGE images. Thus contrast-enhanced MP-RAGE is an alternative to conventional SE imaging in the investigation of intracranial masses. Although the total number of lesions found in patients with demyelinating disease was significantly higher on MP-RAGE, demonstration of blood-brain-barrier breakdown in active lesions was less obvious.     

Delayed encephalopathy of acute carbon monoxide intoxication: diffusivity of cerebral white matter lesions

BACKGROUND AND PURPOSE: Carbon monoxide intoxication has delayed effects on the cerebral white matter characterized by bilateral, confluent lesions that reflect diffuse demyelination. To increase our understanding of this process, we assessed the diffusion characteristics of these lesions. METHODS: Five consecutive patients with delayed encephalopathy of CO intoxication were examined with diffusion MR imaging. Diffusion-weighted images (DWIs) were obtained 25-95 days after their exposure to CO and during a relapse of neuropsychiatric symptoms, which occurred after an initial recovery. Imaging was performed at 1.5 T by using a spin-echo echo-planar sequence with diffusion gradients of 0, 500, and 1000 s/mm(2). DWIs and apparent diffusion coefficient (ADC) maps were visually evaluated, and mean ADCs were calculated from the periventricular white matter and the centrum semiovale, where confluent hyperintensity was seen on T2-weighted images. Findings were compared with those of normal-looking white matter. RESULTS: In all five patients, both T2-weighted images and DWIs showed the white matter lesions as bilateral, diffuse, confluent areas of hyperintensity in the periventricular white matter and centrum semiovale. On ADC maps, these lesions were isointense, with focal areas of hypointensity (n = 4) or diffuse hypointensity (n = 1). Mean ADC values of the white matter lesions were significantly lower than those of normal-looking white matter, regardless of their isointensity or hypointensity on ADC maps (P <.05). CONCLUSION: Bilateral, confluent, white matter lesions in patients with delayed encephalopathy of CO intoxication show decreased diffusivity.