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Preoperative differentiation of benign, atypical and malignant meningiomas would significantly help in surgical planning and treatment. The aim of this study is to look at radio-morphologic behavior of various histopathological types and grades of meningiomas and their diffusion characteristics.We performed an analytical cross-sectional study including all patients operated on for meningiomas at our hospital during January 2016 to July 2018. We studied 38 meningiomas in 38 patients aged 14 to 73 years old. All patients underwent MRI prior to surgery, including diffusion-weighted sequences, in a 1.5T scanner. Signal intensity in T2-weighted images, diffusion-weighted images (b=0, 90 and 1,000), and Apparent Diffusion Coefficient maps within the tumors and in the normal parietal white matter as a reference were evaluated. In the histological study, cellularity, proliferation index, histological grade, and cerebral invasion were evaluated.There was female predilection with male:female ratio of 1:2.4. Most meningiomas were supratentorial with most common origin being parafalcine and convexity. Of the 38 meningiomas, 31 were WHO grade I, 6 were WHO grade II (atypical) and one was WHO grade III (anaplastic). Among various tumors' behaviors, incomplete CSF cleft, pial invasion and parenchymal invasion were significantly high in high-grade tumors. Similarly, tumors showing pial invasion, breached tumor-brain interface, no capsular enhancement and parenchyma invasion showed significantly low NADC. Mean ADC value was 0.722±7.7x10-3 mm2/s (normalized ADC 0.9±0.1) in the atypical group and 0.876±24.56x10-3 mm2/s (normalized ADC 1.11±0.31) in the typical group. No statistically significant differences of ADC/NADC were found between histologic subtypes. Two subtypes of typical meningiomas, metaplastic and angiomatous meningioma had the highest values in the ADC maps.MR morphology like pial invasion, breached tumors brain interface, parenchymal invasion can predict aggressiveness and atypical nature of meningiomas. Meningioma shows moderately restricted diffusion. The signal on the ADC map is associated with tumors cellularity and aggressiveness suggesting its usefulness for predicting the histological grade.

Purpose To develop a novel diffusion-weighted magnetic resonance spectroscopy (DW-MRS) technique in conjunction with J-resolved spatially localized spectroscopy (JPRESS) to measure the apparent diffusion coefficients (ADCs) of brain metabolites beyond N-acetylaspartic acid (NAA), creatine (Cr), and choline (Cho) at 3T. This technique will be useful to probe tissue microstructures in vivo, as the various metabolites have different physiological characteristics. Methods Two JPRESS spectra were collected (high b-value and low b-value), and the ADCs of 16 different metabolites were estimated. Two analysis pipelines were developed: 1) a 2D pipeline that uses ProFit software to extract ADCs from metabolites not typically accessible at 3T and 2) a 1D pipeline that uses TARQUIN software to extract the metabolite concentrations from each line in the 2D dataset, allowing for scaling as well as validation. Results The ADCs of 16 different metabolites were estimated from within six subjects in parietal white matter. There was excellent agreement between the results obtained from the 1D and 2D pipelines for NAA, Cr, and Cho. Conclusion The proposed technique provided consistent estimates for the ADCs of NAA, Cr, Cho, glutamate + glutamine, and myo-inositol in all subjects and additionally glutathione and scyllo-inositol in all but one subject. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.

Cardiovascular risk (CVR) factors may be associated with poor cognitive functioning in elderlies and impairments in brain structure. Using MRI and voxel-based morphometry (VBM), we assessed regional white matter (WM) volumes in a population-based sample of individuals aged 65–75 years (n = 156), subdivided in three CVR subgroups using the Framingham Risk Score. Cognition was assessed using the Short Cognitive Performance Test. In high-risk subjects, we detected significantly reduced WM volume in the right juxtacortical dorsolateral prefrontal region compared to both low and intermediate CVR subgroups. Findings remained significant after accounting for the presence of the APOEε4 allele. Inhibitory control performance was negatively related to right prefrontal WM volume, proportionally to the degree of CVR. Significantly reduced deep parietal WM was also detected bilaterally in the high CVR subgroup. This is the first large study documenting the topography of CVR-related WM brain volume deficits. The significant association regarding poor response inhibition indicates that prefrontal WM deficits related to CVR are clinically meaningful, since inhibitory control is known to rely on prefrontal integrity.

Sustained attention develops during childhood and has been linked to the right fronto-parietal cortices in functional imaging studies; however, less is known about its relation to white matter (WM) characteristics. Here we investigated whether the microstructure of the WM underlying and connecting the right fronto-parietal cortices was associated with sustained attention performance in a group of 76 typically developing children aged 7-13 years. Sustained attention was assessed using a rapid visual information processing paradigm. The two behavioral measures of interest were the sensitivity index d' and the coefficient of variation in reaction times (RTCV ). Diffusion-weighted imaging was performed. Mean fractional anisotropy (FA) was extracted from the WM underlying right dorsolateral prefrontal (DLPFC) and parietal cortex (PC), and the right superior longitudinal fasciculus (SLF), as well as equivalent anatomical regions-of-interest (ROIs) in the left hemisphere and mean global WM FA. When analyzed collectively, right hemisphere ROIs FA was significantly associated with d' independently of age. Follow-up analyses revealed that only FA of right SLF and the superior part of the right PC contributed significantly to this association. RTCV was significantly associated with right superior PC FA, but not with right SLF FA. Observed associations remained significant after controlling for FA of equivalent left hemisphere ROIs or global mean FA. In conclusion, better sustained attention performance was associated with higher FA of WM in regions connecting right frontal and parietal cortices. Further studies are needed to clarify to which extent these associations are driven by maturational processes, stable characteristics and/or experience.

Rationale and Objectives At lower magnetic field strengths, regional differences of cerebral metabolite distributions have been described, but these data are controversial. Magnetic resonance spectroscopy at 7 T is expected to deliver high spectral resolution and good differentiation, but there are problems arising at high magnetic field strengths that may diminish spectral quality. Because there have been only a few studies in humans so far, there are no standard values for 7 T concerning regional metabolite distributions and concentrations. Materials and Methods In the present study, the metabolites detectable with 1 H magnetic resonance spectroscopy, N-acetyl-aspartate, choline, and creatine (Cr), were evaluated with a single-voxel sequence. Five voxels were placed in the frontal and parietal white matter and the insular, thalamic, and occipital gray matter. Results For N-acetyl-aspartate, the lowest values were found in frontal white matter and the highest in thalamic gray matter. Choline displayed the lowest values in frontal white matter and the highest in insular gray matter. Cr showed the lowest values in frontal white matter and the highest in thalamic gray matter. The highest ratio of choline to Cr was found in parietal white matter and the lowest in thalamic gray matter. The highest ratio of N-acetyl-aspartate to Cr was found in thalamic gray matter and the lowest in frontal white matter. Conclusions In the present study, regional cerebral metabolite differences were verified with high-field magnetic resonance spectroscopy. Quantitative values and metabolite ratios could be a basis for further clinical studies.

We report the case of a patient who developed obsessive-compulsive symptoms after being diagnosed with multiple sclerosis. In this patient, obsessive-compulsive symptoms deteriorated with the emergence of a right parietal white matter multiple sclerosis plaque. The involvement of parietal white matter abnormalities in the pathophysiology of obsessive-compulsive disorder remains largely unexplored. Our case report raises the possibility that parietal lobe white matter microstructure plays a role in mediating obsessions and compulsions through disruptions of the functional connectivity between cortical-cortical and/or cortical-subcortical brain regions implicated in the pathophysiology of obsessive-compulsive disorder.

Diffusion tensor imaging (DTI) was used to examine the microstructural integrity of normal appearing white matter (NAWM) in subjects with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Significant frontal, temporal, and parietal white matter diffusion tensor changes were demonstrated in MCI and AD compared with normal controls. These changes were correlated with cognitive functioning, and are consistent with a hypothesized loss of axonal processes in affected regions.

This paper examined whether FreeSurfer - generated data differed between a fully – automated, unedited pipeline and an edited pipeline that included the application of control points to correct errors in white matter segmentation. In a sample of 30 individuals, we compared the summary statistics of surface area, white matter volumes, and cortical thickness derived from edited and unedited datasets for the 34 regions of interest (ROIs) that FreeSurfer (FS) generates. To determine whether applying control points would alter the detection of significant differences between patient and typical groups, effect sizes between edited and unedited conditions in individuals with the genetic disorder, 22q11.2 deletion syndrome (22q11DS) were compared to neurotypical controls. Analyses were conducted with data that were generated from both a 1.5 tesla and a 3 tesla scanner. For 1.5 tesla data, mean area, volume, and thickness measures did not differ significantly between edited and unedited regions, with the exception of rostral anterior cingulate thickness, lateral orbitofrontal white matter, superior parietal white matter, and precentral gyral thickness. Results were similar for surface area and white matter volumes generated from the 3 tesla scanner. For cortical thickness measures however, seven edited ROI measures, primarily in frontal and temporal regions, differed significantly from their unedited counterparts, and three additional ROI measures approached significance. Mean effect sizes for edited ROIs did not differ from most unedited ROIs for either 1.5 or 3 tesla data. Taken together, these results suggest that although the application of control points may increase the validity of intensity normalization and, ultimately, segmentation, it may not affect the final, extracted metrics that FS generates. Potential exceptions to and limitations of these conclusions are discussed.

Abnormal neurodevelopment has been reported for infants who were born with transposition of the great arteries (TGA) and underwent arterial switch operation (ASO). This study evaluates the cerebral metabolism of TGA infants at birth and before ASO and neurodevelopment 1 year after ASO. Proton magnetic resonance spectroscopy (1H-MRS) was performed on 16 full-term TGA brains before ASO within 3-6 days after birth. The brain metabolite ratios of [NAA/Cr], [Cho/Cr], and [mI/Cr] evaluated measured. Ten infants were evaluated at 1 year using the Bayley Scales of Infants Development II (BSED II). Cerebral metabolism of infants with TGA was altered in parietal white matter (PWM) and occipital gray matter (OGM) at birth before ASO. One year after ASO, [Cho/Cr] in PWM remained altered, but all metabolic ratios in OGM were normal. The results of BSID II at 1 year showed delayed mental and psychomotor development. This delayed neurodevelopmental outcome may reflect consequences of the altered cerebral metabolism in PWM measured by 1H-MRS. It is speculated that the abnormal hemodynamics due to TGA in utero may be responsible for the impaired cerebral metabolism and the subsequent neurodevelopmental deficit.

White matter disease (WMD) with pervasive non-focal subtotal tissue loss is frequently seen in Alzheimer's disease (AD) upon neuropathological examination. Although WMD has varying effects on AD symptoms, accurate clinical detection is difficult due partly to scarcity of correlative structural imaging and histopathological studies. Neuropathological studies of WMD severity and distribution have been conducted earlier using semi-quantitative methods. A technique for quantifying WMD objectively in large white matter areas, based on optical density (OD) measurements on images of scanned whole-brain sections, was developed and was validated using conventional microscopic assessment. Altogether, 16 AD cases with concomitant WMD (AD–WMD) and 9 cases of AD without WMD (AD-only) were analysed. The OD values correlated significantly with the neuropathological severity of WMD and were significantly lower in AD–WMD than in AD-only in frontal, frontoparietal, temporal and parietal white matter but not in the occipital white matter, the frontal OD difference being greatest. Useful baseline information on WMD distribution in AD to relate to in vivo imaging results was obtained.

To determine whether differences exist between neurofibromatosis type 1 (NF1) patients with or without focal lesions and healthy normal volunteers in the metabolite ratios of normal appearing white matter, 27 patients with NF1 (with parenchymal lesion, MR positive, n: 17; without parenchymal lesions, MR negative, n: 10) and 20 healthy volunteers underwent MRI and short TE (31 ms) proton MR spectroscopy (MRS). In 17 patients with parenchymal lesions, 61 focal lesions were detected by MRI. MRS was performed from normal appearing frontal and posterior parietal white matter (FWM and PWM) in NF1 and from control groups. NAA/Cr, Cho/Cr and MI/Cr ratios were calculated. Significant increase in Cho/Cr and MI/Cr ratios were found in FWM and PWM in MR negative and positive groups when compared to control group. NAA/Cr ratio in MR positive group was significantly decreased in FWM compared to control group. There were no significant differences between FWM and PWM in all metabolite ratios of MR negative group. MI/Cr ratio in MR positive group was significantly elevated in PWM compared to FWM. Metabolite changes detected by MRS could indicate demyelination and gliosis in normal appearing white matter in all NF1 patients, and additionally neuroaxonal damage in the FWM of NF1 patients with focal lesions. For that reason, in the clinical evaluation and follow-up of these patients MRS features of normal appearing white matter should be considered in addition to focal lesions.

The most widely accepted model of obsessive-compulsive disorder (OCD) assumes brain abnormalities in the "affective circuit", mainly consisting of volume reduction in the medial orbitofrontal, anterior cingulate and temporolimbic cortices, and tissue expansion in the striatum and thalamus. The advent of whole-brain, voxel-based morphometry (VBM) has provided increasing evidence that regions outside the "affective" orbitofronto-striatal circuit are involved in OCD. Nevertheless, potential confounds from the different image analysis methods, as well as other factors, such as patients' medication and comorbidity status, may limit generalization of results. In the present paper, we systematically reviewed the whole-brain VBM literature on OCD by focussing specifically on degree of consistency between studies, extent to which findings have been replicated and interrelation between clinical variables and OCD anatomy, a potentially crucial factor that has been systematically examined only in a limited number of studies. The PubMed database was searched through February 2012. A total of 156 studies were identified; 18 of them fulfilled the inclusion/exclusion criteria and included 511 patients and 504 controls. Results support the notion that the brain alterations responsible for OCD are represented at the network level, and that widespread structural abnormalities may contribute to neurobiological vulnerability to OCD. Apart from defects in regions within the classic "affective" circuit, volume reduction of the cortical source of the dorsolateral (DL) prefronto-striatal "executive" circuit (dorsomedial, DL, ventrolateral and frontopolar prefrontal cortices), and of reciprocally connected regions (temporo-parieto-occipital associative areas) is consistently described in OCD patients. Moreover, increased volume of the internal capsule and reduced frontal and parietal white matter volumes may account for altered anatomical connectivity in fronto-subcortical circuitry. Morphometric changes in both "affective" and "executive" parallel the disease clinical course, being at the same time responsible for variation in symptom severity. Thus, OCD mechanisms involve a more widespread network of cerebral dysfunctions than previously thought, which may explain the heterogeneity in clinical manifestations and symptom severity.

Diffusion tensor magnetic resonance imaging (MRI) was used to study the microstructural integrity of white matter in adults with poor or normal reading ability. Subjects with reading difficulty exhibited decreased diffusion anisotropy bilaterally in temporo-parietal white matter. Axons in these regions were predominantly anterior–posterior in direction. No differences in T1-weighted MRI signal were found between poor readers and control subjects, demonstrating specificity of the group difference to the microstructural characteristics measured by diffusion tensor imaging (DTI). White matter diffusion anisotropy in the temporo-parietal region of the left hemisphere was significantly correlated with reading scores within the reading-impaired adults and within the control group. The anisotropy reflects microstructure of white matter tracts, which may contribute to reading ability by determining the strength of communication between cortical areas involved in visual, auditory, and language processing.

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit drug that has been associated with serotonergic axonal degeneration in animals. This study evaluates neurochemi- cal abnormalities in recreational MDMA users. Twenty-two MDMA users and 37 normal subjects were evaluated with magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1H MRS) in the mid-frontal, mid- occipital, and parietal brain regions. 1H MRS showed nor- mal N-acetyl (NA) compounds in all brain regions. The myo-inositol (MI) concentration (116.3%, P 5 0.04) and the MI to creatine (CR) ratio (114.1%, P 5 0.01) were increased in the parietal white matter of MDMA users. The cumula- tive lifetime MDMA dose showed significant effects on (MI) in the parietal white matter and the occipital cortex. The normal NA concentration suggests a lack of significant neuronal injury in recreational MDMA users. However, the usage-related increase in MI suggests that exposure to MDMA, even at recreational doses, may cause increased glial content. J. Magn. Reson. Imaging 1999;10:521-526. r 1999 Wiley-Liss, Inc.

This study was designed to measure T1 and T2 relaxation times of the singlets in normal brain at 7T. Our results demonstrated that the T1 relaxation values of total creatine (tCr)-CH3 and N-acetyl aspartate (NAA) in the parietal white matter significantly increased at 7T compared to 3T, while the T1 of Choline-containing compounds (Cho) was similar between field strengths.

Purpose To establish normative metabolite ratios throughout the newborn brain using three-dimensional (3D) MR spectroscopic imaging (MRSI). Materials and Methods MRI and MRSI have been valuable tools for assessing normal and abnormal neuronal maturation for newborns. In this study, we performed whole brain 3D MRSI in addition to comprehensive anatomic and other functional imaging methods to examine maturation. Fifty-five newborn subjects (28.4 ± 2.6 weeks postconception age at birth, 34.1 ± 3.1 weeks postconception age at scan, 32 males and 23 females) had high quality MRSI studies (104 exams) and normal neurodevelopmental outcome (neuromotor score = 0, mental development index score > 85) at age 12 months. Results The NAA to Cho ratio increased significantly with age for all regions. Lac to NAA ratio decreased significantly with age in the regions of thalamus, basal ganglia, cortical spinal tract, and parietal white matter, and showed a decreasing trend in the other regions. Conclusion Brain metabolites can be obtained through in vivo 3D MRSI and used to monitor newborn brain maturation. J. Magn. Reson. Imaging 2011;33:306–311. © 2011 Wiley-Liss, Inc.

Objective: To evaluate brain metabolism in subjects with partial ornithine transcarbamylase deficiency (OTCD) utilizing 1 H MRS. Methods: Single-voxel 1 H MRS was performed on 25 medically-stable adults with partial OTCD, and 22 similarly aged controls. Metabolite concentrations from frontal and parietal white matter (FWM, PWM), frontal gray matter (FGM), posterior cingulate gray matter (PCGM), and thalamus (tha) were compared with controls and IQ, plasma ammonia, glutamine, and disease severity. Results: Cases ranged from 19 to 59 years; average 34 years; controls ranged from 18 to 59 years; average 33 years. IQ scores were lower in cases (full scale 111 vs. 126; performance IQ 106 vs. 117). Decreased myoinositol (mI) in FWM ( p = 0.005), PWM ( p p = 0.003), and tha ( p = 0.004), identified subjects with OTCD, including asymptomatic heterozygotes. Glutamine (gln) was increased in FWM ( p p p = 0.002), and PCGM ( p = 0.001). Disease severity was inversely correlated with [mI] in PWM ( r = −0.403; p = 0.046) and directly correlated with [gln] in PCGM ( r = 0.548; p = 0.005). N -Acetylaspartate (NAA) was elevated in PWM ( p = 0.002); choline was decreased in FWM ( p = 0.001) and tha ( p = 0.002). There was an inverse relationship between [mI] and [gln] in cases only. Total buffering capacity (measured by [mI/mI + gln] ratio, a measure of total osmolar capacity) was inversely correlated with disease severity in FWM ( r = −0.479; p = 0.018), PWM ( r = −0.458; p = 0.021), PCGM ( r = −0.567; p = 0.003), and tha ( r = −0.345; p = 0.037). Conclusion: Brain metabolism is impaired in partial OTCD. Depletion of mI and total buffering capacity are inversely correlated with disease severity, and serve as biomarkers.

24 patients with clinically isolated optic neuritis (ON) were examined with MRI. Only 5 patients (22.9%) had a normal MRI scan. The number of detected clinically silent lesions ranged from 0 to 38. They were mainly located in the frontal and parietal white matter. All patients with more than 3 lesions on MRI had pathological findings in CSF. There was no correlation between the number and location of lesions and age at onset of ON.

Purpose: To evaluate the efficacy of a fully automatic, single-voxel, proton MR spectroscopy algorithm on a 3.0T MR system.Methods: The PROBE/SVQ algorithm (GE Medical Systems) was evaluated on a General Electric (GE) Signa LX-3T system. Ten normal volunteers (female, 21.1±2.0 years old) participated in the study. Nine representative regions of interest were examined, namely, right and left frontal white matter; right and left parietal white matter; right and left basal ganglia; right and left dentate nucleus; and pons.Results: The mean coefficients of variation in all regions for the N-acetyl-aspartate to creatine ratio (NAA/Cr), choline to creatine ratio (Cho/Cr), and choline to N-acetyl-aspartate ratio (Cho/NAA) were 10.2±2.4%, 11.4±3.2% and 12.6±1.4%, respectively.Conclusion: A fully automated spectroscopic examination under clinical setting utilizing the PROBE/SVQ algorithm appears to be a reliable method, extending the window of routine clinical assessment of brain metabolism.

Magnetic resonance imaging (MRI) of the brain was arranged. The T2-weighted images showed multifocal, high-intensity lesions within the white matter. The affected areas included the right internal capsule, the left external capsule and the left parietal white matter. The left parietal lesion mirrored the grey–white junction, resulting in the typical ‘scalloped’ appearance.1 There was no mass effect, no gadolinium enhancement (not shown) and the blood–brain barrier Correspondence to: Graham Norton, Department of Medicine, Modbury Hospital, 113 Smart Road, Modbury, SA 5092, Australia. Email: gn@smart-road.com.au

Even after the precipitant of a hepatic encephalopathy (HE) episode is treated,lactulose is often continued indefinitely. Clinical tools to predict relapse off of lactulose and guide the safe withdrawal of Rx have not been studied. Aim: Evaluate change in psychometric & MR spectroscopic(MRS)after lactulose withdrawal. Methods: Cirrhotics with prior HE underwent number connection (NCT-A/B),Block design(BDT),Digit symbol(DST)& Inhibitory control tests(ICT;lures are the outcomes) & MRS while on lactulose. Lactulose was then withdrawn. Psychometric tests were repeated 2,14& 30 days post-withdrawal. MRS was repeated 14 days post-withdrawal. Occipital gray(GM) & right parietal white matter(WM) regions were studied for glutamine(Gln), myoinositol & choline. Worsening HE leads to increase in Gln. Repeated measures analyses were used to model tests over time & determine relapse predictors. Results: 7 cirrhotics (age 53±7yrs,5 HCV,2 alcohol) on lactulose for 6±5 mths for precipitated HE(5 GI bleed, 2 infections) were included.3 patients clinically relapsed 38±6 days post-withdrawal; all 3 had >15 ICT lures while on lactulose. None of those who scored 15 ICT lures on lactulose relapsed. Gln levels in gray/white matter increased after lactulose withdrawal. Psychometric performance on therapy can predict the risk of relapse off of lactulose treatment.

Purpose : To evaluate regional differences in relative metabolite ratios in the normal human brain by 1H MRspectroscopy (MRS), and compare the spectral quality obtained by the automated prescan method (PROBE) and themanual method. Materials and Methods : Localized 1H MRS was performed on a GE 1.5T SIGNA MRI/MRS system (version5.5) with active shielded gradients. For 20 normal volunteers aged 8-47 years, spectral parameters were adjustedby the auto-prescan routine provided by a PROBE package(N=34)and manually (N=33). Five regions of the human brainwere examined (N=PROBE,manual): frontal white matter(N=6,10), parietal white matter(N=8,9), basal ganglia(N=6,5),thalamus(N=4,5), and cerebellum(N=4,4). For all spectra, a STEAM localization sequence with three-pulse CHESS H2Osuppression was used, with the following acquisition parameters: TR=3.0 sec, TE=30 msec, TM=13,7 msec, SW=2500Hz,SI=2048 pts, AVG=48, and NEX=2. Results : A total of 61 reliable spectra were obtained by PROBE (28/34=82%success) and by the manual method (33/33=100% success). Regional differences in the spectral patterns of the fiveregions were clearly demonstrated by both PROBE and the manual methods. For prescanning, the manual method tookslightly longer than PROBE (3-5 mins and 2 mins,respectively). There were no significant differences in spectralpatterns and relative metabolic ratios between the two methods. However, auto-prescan by PROBE seemed to be veryvulnerable to slight movement by patients, and in three cases, an acceptable spectrum was thus not obtained.Conclusion : PROBE is a highly practical and reliable method for single voxel 1H MRS of the human brain; the twomethods of prescanning do not result in significantly different spectral patterns and the relative metaboliteratios. PROBE, however, is vulnerable to slight movement by patients, and if the success rate for obtainingquality spectra is to be increased, regardless of the patient's condition and the region of the brain, it must beused in conjunction with the manual method.

Optic neuritis (ON) is known as a symptom of a number of diseases (see table 1), but is most frequently seen in patients with multiple sclerosis (MS). If ON of unknown origin (see table 2) occurs isolated without any other clinical abnormality, the question arises as to if it represents a disease entity for itself or is the initial symptom of MS. In literature, the percentage of patients developing MS after one or more episodes of isolated ON ranges from 11.5% to 85% (1). This information is mainly based on clinical long term follow-up and sometimes supplemented by computerized tomography.

Positron emission tomography (PET) and magnetic resonance imaging (MRI) studies were performed on a case of neuro-Behçet's syndrome. In accordance with the clinical signs, FDG PET (using 18F-labeled 2-F-2'-desoxyglucose) revealed disseminated storage defects in the cerebrum and cerebellum. Focal regions of enhanced signal intensity were demonstrated in the parietal white matter of the cerebrum in T2-weighted images and in the brain stem by MRI.

In a patient with the syndrome of crural paresis and homolateral ataxia, administration of trihexyphenidyl resulted in improvement of disabling unilateral ataxia and gross intention tremor. Symptoms returned when drug therapy was interrupted. CT showed a radiolucent lesion deep in the parietal white matter close to the internal capsule.