Early- and late-state subacute sclerosing panencephalitis: chemical shift imaging and single-voxel MR spectroscopy

BACKGROUND AND PURPOSE: Subacute sclerosing panencephalitis (SSPE) is a rare, progressive, inflammatory neurodegenerative disease. Our aim was to determine the metabolic abnormalities of brain in early- and late-stage SSPE by using MR spectroscopy and to assess areas of involvement in the early stages when MR imaging findings were normal. METHODS: Children with stage II (n = 3) or III (n = 3) SSPE and 10 healthy, age-matched children underwent MR imaging, multivoxel MR spectroscopy, and short-echo single-voxel MR spectroscopy (SVS). Areas of involvement in the brain were determined with chemical shift imaging. For SVS, 2 x 2 x 2-cm voxels were placed in the frontal subcortical white matter (FSWM) and parieto-occipital white matter (POWM). N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (Ins)/Cr, and NAA/Cho ratios were calculated. RESULTS: Comparisons of NAA/Cr, Cho/Cr, Ins/Cr and NAA/Cho ratios between patients and control subjects showed significant differences in FSWM and POWM (P <.01). In patients with SSPE, NAA/Cr ratios in POWM were significantly less than those in FSWM (P <.01). NAA/Cr ratios in patients with stage II SSPE and those in the control group were not significantly different; this may reflect the absence of neuronal loss. Decreased NAA/Cr, increased Cho/Cr and Ins/Cr ratios, and increased lactate and lipid peaks were found in patients with stage III SSPE. CONCLUSION: MR spectroscopy showed findings suggestive of inflammation in stage II and findings of demyelination, gliosis, cellular necrosis, and anaerobic metabolism in stage III. MR spectroscopy could be a promising technique for early diagnosis and treatment planning in cases of SSPE.     

Developmental delay in children: assessment with proton MR spectroscopy

BACKGROUND AND PURPOSE: The cause of developmental delay frequently is unknown, and clinicians and families can be frustrated by the lack of neuroimaging correlation especially when considering therapeutic options and long-term prognosis. We sought to determine if proton MR spectroscopy can depict abnormalities in patients with developmental delay who have structurally normal brain MR images. METHODS: Children with developmental delay who were older than 2 years (mean age, 5.0 years; range, 3.0-10.0 years) and those aged 2 years or younger (mean age, 1.5 years; range, 0.5-2.0 years) and age-matched control subjects for each patient group underwent brain MR imaging and proton MR spectroscopy. A point-resolved spectroscopy sequence (2000/144 [TR/TE]) was used. Voxels (8 cm(3)) were placed in the subcortical white matter of the frontal and parieto-occipital lobes bilaterally. N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were assessed. RESULTS: All patients had normal brain MR images. In children with developmental delay who were aged 2 years or younger, no statistically significant differences were detected in the NAA/Cr or Cho/Cr ratios compared with those of the control subjects. In children with developmental delay who were older than 2 years, decreases in the NAA/Cr ratio were observed in frontal (P <.001) and parieto-occipital (P <.017) subcortical white matter, and elevations in the Cho/Cr ratio were detected in the frontal (P <.24) and parieto-occipital (P <.002) subcortical white matter compared with age-matched control subjects. CONCLUSIONS: In children with developmental delay who are older than 2 years, proton MR spectroscopy depicted abnormalities in the NAA/Cr and Cho/Cr ratios. Proton MR spectroscopy should be performed as part of the neuroimaging evaluation of developmental delay. Further studies will be needed to determine if abnormalities detected with proton MR spectroscopy can be used as a diagnostic tool and neuroimaging marker to assess long-term functional outcome.     

Multivoxel proton MR spectroscopy in malformations of cortical development

BACKGROUND AND PURPOSE: Malformations of cortical development (MCD) are traditionally considered as a cause of epilepsy. Our aim was to study patients with focal MCD, by using multivoxel proton MR spectroscopy; we focused not only on the lesion but also on the normal-appearing contralateral side (NACS). Our hypothesis was that the metabolic abnormality extends to the NACS; therefore, it would be inadequate to consider NACS as an internal control. MATERIALS AND METHODS: We studied 16 patients with focal MCD. MR spectroscopy was performed by using a point-resolved spectroscopy sequence technique, including the MCD area and the NACS. In each volume of interest, a smaller volume of interest of 2.25 cm(3) centered on the MCD was selected to study the N-acetylaspartate/creatine (NAA/Cr) ratio. In NACS, this ratio was studied by placing a symmetric voxel in comparison with the smaller MCD volume of interest. A control group (n=30) was also studied to evaluate both white and gray matter by using the same MR spectroscopy protocol. RESULTS: From 16 analyzed volumes of interest with MCD, 9 were composed of gray matter heterotopia and 7 of cortical dysplasia. MR spectroscopy of both MCD lesions and NACS (n=10) showed decreased NAA/Cr compared with that of the control group. NACS in these patients did not present significant differences regarding NAA/Cr in comparison with the affected side. CONCLUSIONS: MR spectroscopy demonstrated abnormal NAA/Cr in both MCD lesions and NACS in patients harboring focal MCD, giving support to the hypothesis that in MCD metabolic abnormalities extend far away from the limits of the lesion, reaching the contralateral side.     

Reference values for long echo time MR spectroscopy in healthy adults

BACKGROUND AND PURPOSE: There is a lack of information with regard to normal metabolic ratios acquired with MR spectroscopy utilizing a long echo time technique. Our purpose was to measure metabolic ratios in healthy adults to determine whether the metabolites varied across brain regions and by sex. METHODS: Single voxel proton spectra were acquired with an echo time of 135 milliseconds in 10 brain regions of 72 healthy subjects ranging in age from 20 to 44 years. Six gray matter sites in the cerebrum included four cortical areas in the frontal, parietal, temporal, and occipital lobes, and two deep nuclear sites in the basal ganglia and the thalamus. Two subcortical white matter regions were in the parietal and the frontal lobes. Two posterior fossa sites included the pons and the cerebellum. All 10 brain regions were not studied in each subject. For each spectrum, the metabolites n-acetylaspartate (NAA), creatine (Cr), and choline (Ch) were identified and ratios of NAA/Cr and Ch/Cr calculated for each brain region. A multifactorial analysis of variance was performed with the two metabolic ratios as dependent variables and with brain region and sex as independent variables. Post hoc statistical analysis consisted of the Scheffé F statistic for significant difference between pairs of brain regions for both metabolic ratios. RESULTS: There was significant regional variation for both the NAA/Cr ratio (P < .0001) and the Ch/Cr ratio (P < .0001). The NAA/Cr ratio was consistent within cortical gray and white matter but differed between cortical gray (smaller ratio) and white matter (larger ratio). The Ch/Cr ratio was variable in the gray matter, differed between some but not all gray and white matter regions, but was consistent within subcortical white matter regions. There was no difference between men and women for either metabolic ratio. CONCLUSION: There was variation of the NAA/Cr ratio and the Ch/Cr ratio across brain regions, but no sex differences were found. These findings provide the requisite normative values to use single voxel, long-echo-time MR spectroscopy in adult patients with neurologic disorders.     

Evaluation of treatment-induced cerebral white matter injury by using diffusion-tensor MR imaging: initial experience

BACKGROUND AND PURPOSE: Treatment with chemotherapy and radiation therapy for brain tumors can cause white matter (WM) injury. Conventional MR imaging, however, cannot always depict treatment-induced transient WM abnormalities. We investigated the ability of diffusion-tensor (DT) MR imaging and proton MR spectroscopy to detect the treatment-induced transient changes within normal-appearing WM. METHODS: DT MR imaging and proton MR spectroscopy were performed in 8 patients treated with a combination of surgery, chemotherapy, and radiation therapy for brain tumors (17 examinations) and 11 age-matched controls. Apparent diffusion coefficient (ADC) value, fractional anisotropy (FA) value, and N-acetylaspartate (NAA)/creatine (Cr) ratio were obtained from 27 hemispheres with normal-appearing WM in the patients. We divided the datasets of isotropic ADC, FA, and NAA/Cr, on the basis of the time period after completion of radiation therapy, into 4 groups: group 1 (0-2 months; n = 10), group 2 (3-5 months; n = 5), group 3 (6-9 months; n = 7), and group 4 (10-12 months; n = 5). We compared averages of mean isotropic ADC, mean FA, and NAA/Cr of each patient group with those of the control group by using a t test. RESULTS: In the group 2, averages of mean FA and NAA/Cr decreased and average of mean isotopic ADC increased in comparison with those of the control group (P = .004, .04, and .0085, respectively). There were no significant differences in the averages between the control group and patient groups 1, 3, and 4. CONCLUSION: DT MR imaging and proton MR spectroscopy can provide quantitative indices that may reflect treatment-induced transient derangement of normal-appearing WM.     

Congenital muscular dystrophy with merosin deficiency: 1H MR spectroscopy and diffusion-weighted MR imaging

PURPOSE: To prospectively use hydrogen 1 ((1)H) magnetic resonance (MR) spectroscopy and apparent diffusion coefficient (ADC) maps to try to explain the discrepancy between the extensive white matter (WM) abnormalities observed at MR imaging and the relatively mild neurocognitive decline in patients with merosin-deficient congenital muscular dystrophy (CMD). MATERIALS AND METHODS: The hospital ethics committee approved this study, and informed consent was obtained. Nine patients (five boys, four girls; age range, 3-9 years; mean, 6 years +/- 2 [standard deviation]) with merosin-deficient CMD underwent T1-weighted, T2-weighted, fluid-attenuated inversion recovery, and diffusion-weighted MR imaging and (1)H MR spectroscopy, which was performed in the parieto-occipital WM (POWM) and frontal WM (FWM) by using stimulated-echo acquisition mode. Metabolite (N-acetylaspartate [NAA], choline-containing compounds [Cho], and myo-inositol [mI]) ratios were calculated in relation to creatine/phosphocreatine (Cr) and water (H(2)O). NAA/Cho was also calculated. ADCs were calculated in approximately the same locations that were studied with spectroscopy. For comparison, (1)H MR spectroscopy (n = 10) and ADC mapping (n = 7) were also performed in 10 healthy age- and sex-matched control subjects (three boys, seven girls; age range, 4-9 years; mean, 6 years +/- 1). Statistical analysis involved the t test for comparison between different groups; correlation between ADC and spectroscopy results was studied with the Pearson test. RESULTS: MR imaging revealed evidence of bilateral WM involvement in all patients. Whereas their NAA/Cr and Cho/Cr were normal, their mI/Cr was slightly increased compared with that in control subjects (P = .03 in FWM and P = .07 in POWM), and their NAA/Cho was decreased in POWM (P = .03). NAA/H(2)O, Cr/H(2)O, Cho/H(2)O, and mI/H(2)O were considerably decreased (P < .05 for all) and ADC values were increased (P < .001) in WM in all patients versus these values in WM in control subjects. There was significant correlation between ADC values and metabolite/water ratios (r = -0.777 to -0.967, P < .05). CONCLUSION: ADC mapping and (1)H MR spectroscopy reveal abnormally high free-water concentrations in the WM of patients with merosin-deficient CMD.     

Relapsing-remitting multiple sclerosis: metabolic abnormality in nonenhancing lesions and normal-appearing white matter at MR imaging: initial experience

PURPOSE: To quantify, with three-dimensional proton magnetic resonance (MR) spectroscopy, metabolic characteristics of normal-appearing white matter and nonenhancing lesions in patients with relapsing-remitting multiple sclerosis (MS). MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. Nine patients with relapsing-remitting MS (six women, three men) and nine age-matched control subjects (seven women, two men) were studied with T1- and T2-weighted MR imaging and three-dimensional proton MR spectroscopy at spatial resolution less than a cubic centimeter. Absolute N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were obtained from 171 voxels: 66 from lesions on T2-weighted MR images (43 hypointense and 23 isointense on T1-weighted MR images), 31 from normal-appearing white matter, and 74 from analogous normal white matter regions on images in control subjects. RESULTS: Mean NAA level in hypointense lesions (5.30 mmol/L +/- 2.27 [standard deviation]) was significantly lower (P < or = .05) than that in isointense lesions (7.82 mmol/L +/- 2.28), normal-appearing white matter (7.37 mmol/L +/- 1.71), and normal white matter in control subjects (8.89 mmol/L +/- 1.54). Cho (1.79 mmol/L +/- 0.65) and Cr (5.64 mmol/L +/- 1.50) levels in isointense lesions were indistinguishable from those in normal-appearing white matter (1.74 mmol/L +/- 0.46 and 4.99 mmol/L +/- 0.97, respectively) but were significantly higher (Cho, 20%; Cr, 24%) than those in normal white matter in control subjects (1.44 mmol/L +/- 0.40 and 4.30 mmol/L +/- 1.32, respectively). NAA, Cho, and Cr levels in normal-appearing white matter were significantly different than those in normal white matter in control subjects (NAA, 20% lower; Cho, 14% higher; and Cr, 17% higher). CONCLUSION: Abnormal metabolic activity persists in all MS tissue types. Increased Cr and Cho levels suggest (a) ongoing gliosis and attempted remyelination in isointense lesions on T1-weighted MR images and (b) membrane turnover (de- and remyelination), in addition to increased cellularity (gliosis, inflammation) in normal-appearing white matter.     

Subcortical gray matter N-acetylaspartate reduction in two cases of vascular dementia

Many of the previous studies of vascular dementia using proton magnetic resonance (MR) spectroscopy had been carried out on white matter. However, no proton spectroscopic data of the subcortical gray matter are available in such disease. We report two cases suffering from vascular dementia, with an unilateral N-acetylaspartate (NAA) decrease on subcortical gray matter. This significant reduction in NAA ratios was associated with an increase of choline on the ipsilateral centrum semiovale. We discuss the pathophysiology of these cases.     

Reduced N-acetylaspartate levels in the frontal cortex of 3,4-methylenedioxymethamphetamine (Ecstasy) users: preliminary results

BACKGROUND AND PURPOSE: The perceived safety of the recreational drug methylenedioxymethamphetamine (MDMA), or Ecstasy, conflicts with animal evidence indicating that MDMA damages cortical serotonin (5-HT) neurons at doses similar to those used by humans. Few data are available about the effects of MDMA on the human brain. This study was designed to evaluate MDMA-related alterations in metabolite ratios with single-voxel proton ((1)H) MR spectroscopy. METHODS: Fifteen male MDMA users (mean lifetime exposure, 723 tablets; mean time since last tablet, 12.0 weeks) and 12 age-matched control subjects underwent single-voxel (1)H MR spectroscopy. N-Acetylaspartate (NAA)/creatine (Cr), NAA/Choline (Cho), and myoinositol (MI)/Cr ratios were measured in midfrontal gray matter, midoccipital gray matter, and right parietal white matter. Data were analyzed with linear model-based multivariate analysis of variance. RESULTS: NAA/Cr (P =.04) and NAA/Cho (P =.03) ratios, markers associated with neuronal loss or dysfunction, were reduced in the frontal cortex of MDMA users. Neither NAA/Cr (P =.72) nor NAA/Cho (P =.12) ratios were different between both groups in occipital gray matter and parietal white matter (P =.18). Extent of previous MDMA use and frontal cortical NAA/Cr (rho = -.50, P =.012) or NAA/Cho (rho = -.550, P <.01) ratios were significantly associated. CONCLUSION: Reduced NAA/Cr and NAA/Cho ratios at (1)H MR spectroscopy provide evidence for neuronal abnormality in the frontal cortex of MDMA users; these are correlated with the degree of MDMA exposure. These data suggest that MDMA may be a neurotoxin in humans, as it is in animals.     

MR spectroscopy in gliomatosis cerebri

BACKGROUND AND PURPOSE: The diagnosis of gliomatosis cerebri with MR imaging is known to be difficult. We report on the value of MR spectroscopy in the diagnosis, grading, and biopsy planing in eight patients with histopathologically proved gliomatosis cerebri. METHODS: Patients underwent MR imaging and MR spectroscopy (single-voxel point-resolved spectroscopy [PRESS] at 1500/135, and chemical-shift imaging [CSI] PRESS at 1500/135) before open (n = 4) or stereotactic (n = 4) biopsy. In six patients who underwent CSI, biopsy samples were taken from regions of maximally elevated levels of choline/N-acetylaspartate (Cho/NAA). RESULTS: All patients showed elevated Cho/creatine (Cr) and Cho/NAA levels as well as varying degrees of decreased NAA/Cr ratios, which were most pronounced in the anaplastic lesions. In low-grade lesions, there was a maximum Cho/NAA ratio of 1.3, whereas in anaplastic tumors, the maximum Cho/NAA level was at least 2.5. Spectra in two patients with grade III lesions revealed a lactate peak; lactate and lipid signals were seen in two patients with grade IV lesions. Biopsy specimens from regions with maximally elevated levels of Cho/NAA showed dense infiltration of tumor cells. CONCLUSION: MR spectroscopy might be used to classify gliomatosis cerebri as a stable or a progressive disease indicating its potential therapeutic relevance.     

Neurometabolism of active neuropsychiatric lupus determined with proton MR spectroscopy.

PURPOSETo determine the neurometabolism of patients with active neuropsychiatric systemic lupus erythematosus (NPSLE) by using proton MR spectroscopy.METHODSThirty-six patients with SLE and eight control subjects were studied with proton MR spectroscopy to measure brain metabolites. Peaks from N-acetylaspartate (NAA), creatine (Cr), choline (Cho), and at 1.3 parts per million (ppm) lipid, macromolecules, and lactate were measured. Patients were classified as having major NPSLE (seizures, psychosis, major cognitive dysfunction, delirium, stroke, or coma) (n = 15) or minor NPSLE (headache, minor affective disorder, or minor cognitive disorder) (n = 21). Patients with major NPSLE were severely ill and hospitalized.RESULTSSLE patients had lower NAA and increased metabolites at 1.3 ppm than did control subjects (NAA/Cr(SLE) = 1.90 +/- 0.35, NAA/Cr(Control) = 2.16 +/- 0.26; 1.3 ppm/Cr(SLE) = 0.49 +/- 0.41, 1.3 ppm/Cr(Control) = 0.27 +/- 0.05). NAA/Cr in patients with current or prior major NPSLE was lower than in patients without major NPSLE. Increased peaks at 1.3 ppm were present in all SLE subgroups, but particularly in patients with major NPSLE. These resonances were not evident at an echo time of 136, indicating that these signals were not lactate.CONCLUSIONMajor NPSLE, past or present, is associated with decreased levels of NAA. Elevated peaks around 1.3 ppm do not represent lactate even in severely ill patients, indicating that global ischemia is not characteristic of NPSLE. Neurochemical markers determined by MR spectroscopy may be useful for determining activity and degree of brain injury in NPSLE.     

Correlation of MR imaging and MR spectroscopy findings with cognitive impairment in mucopolysaccharidosis II

BACKGROUND AND PURPOSE: There are no reliable markers to predict neurologic outcome of patients with mucopolysaccharidosis (MPS) II. We hypothesized that brain MR imaging and MR spectroscopy are useful in depicting features related to cognitive impairment (CI) in MPS II. MATERIALS AND METHODS: Nineteen male patients with MPS II were included in this study. They were evaluated through intelligence/developmental tests to be classified in 2 groups: patients with CI (group A) or patients without CI (group B). Brain MR imaging evaluated white matter (WM) lesions, hydrocephalus, and brain atrophy. Voxels from MR spectroscopy (point-resolved spectroscopy TE 30 ms) were positioned in the WM of the deep right frontal lobe and at the gray matter (GM) in the posterior occipital cortex across the midline. Comparison of MR imaging and MR spectroscopy findings between these 2 groups and a control group was performed. RESULTS: The mean age of the patients was 9.6 years (group A, 7.08 years old, 12 patients; group B, 14 years old, 7 patients; P = .076). Brain atrophy and hydrocephalus were more frequently found in group A patients (P=.006 and P=.029, respectively); these patients also presented more severe WM lesions than patients from group B (P=.022). Patients from group A also had a higher myo-inositol (mIns)/creatine (Cr) ratio in the GM (P=.046) and in the WM (P=.032). The choline/Cr and N-acetylaspartate/Cr ratios were similar in both groups. CONCLUSIONS: Our study showed that severe WM lesions, brain atrophy, hydrocephalus, and elevated mIns/Cr were more common in patients with MPS II and with CI.     

Subcortical damage and cortical functional changes in men and women with Fabry disease: a multifaceted MR study

PURPOSE: To prospectively compare brain magnetic resonance (MR) imaging and hydrogen 1 (1H) MR spectroscopy findings and to use functional MR imaging to explore the patterns of brain activation in men and women with Fabry disease (FD). MATERIALS AND METHODS: Eight men and eight women with FD (mean age, 38.8 years +/- 13.9 [standard deviation]) with absent or mild neurologic deficit and 16 healthy control subjects (eight men and eight women; mean age, 42.7 years +/- 15.3) gave informed consent to participate in the study, which was approved by the local ethical committee. Patients and control subjects underwent MR imaging, 1H MR spectroscopy of the frontal cortex and subcortical white matter, and functional MR imaging during repetitive flexion-extension of the last four fingers of the right hand. Extent of cerebral white matter damage was rated on fluid-attenuated inversion recovery MR images by using a visual score. Areas of activation were identified by using statistical parametric mapping software and the adoption of a height threshold of P < .001 (uncorrected) and an extent threshold of P < .05 (corrected). RESULTS: Men and women with FD showed a similar distribution of cerebral white matter changes, lacunar and cortical infarcts, small hemorrhages, and vertebrobasilar dolichoectasia. No significant (P > .05) difference was observed between patients with FD and control subjects for concentration of N-acetylaspartate, creatine, and choline. During the motor task, patients showed recruitment of additional cortical areas in comparison with control subjects. Increased activation of the contralateral sensorimotor area correlated (P = .002) with extent of white matter damage. CONCLUSION: Subcortical ischemic changes in men and women with FD are similar and are associated with increased recruitment of the sensorimotor network during a simple motor task, which might limit the functional effect of the white matter small-vessel disease.     

Disarrangement of fiber tracts and decline of neuronal density correlate in glioma patients--a combined diffusion tensor imaging and 1H-MR spectroscopy study

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) and MR spectroscopy are noninvasive, quantitative tools for the preoperative assessment of gliomas with which the quantitative parameter fractional anisotropy (FA) and the concentration of neurometabolites N-acetylaspartate (NAA), choline (Cho), creatine (Cr) of the brain can be determined. Measurements of FA and NAA reflect the integrity of fiber tracts and the presence of neurons, respectively. This investigation examines changes of FA and NAA and compares these different aspects in architecture of gliomas after spatial coregistration. METHODS: DTI and chemical shift (1)H-MR spectroscopy was performed in 34 healthy volunteers and 69 patients with histologically confirmed (n = 48) or morphologically suspected (n = 21) non-necrotic brain glioma. Volumes of interest (VOIs) were placed in the tumor center (TC), the tumor border (TB), the normal-appearing white matter adjacent to the tumors (TNWM), and in the white matter of the contralateral hemisphere (NWMC). Median FA values and NAA/Cr and NAA/Cho ratios were calculated in the patients' VOIs and the gray and white matter of the volunteers. Correlations of FA values and NAA ratios were calculated. RESULTS: Continuous changes of FA and NAA from the tumor center to the periphery (the adjacent white matter and the contra-lateral hemisphere, respectively) were observed, where median values were: TC: 0.73 +/- 0.45, 0.47 +/- 0.58, 0.17 +/- 0.15 (NAA/Cr, NAA/Cho, FA); TB: 1.06 +/- 0.53, 1.00 +/- 0.15, 0.23 +/- 0.08; TNWM: 1.42 +/- 2.48, 1.21 +/- 0.95, 0.34 +/- 0.09; and NWMC: 1.63 +/- 0.72, 1.56 +/- 1.34, 0.38 +/- 0.08. Correlation of median FA values and NAA ratios in the cumulative group of patients was high (r = 0.99 [NAA/Cr], 0.95 [NAA/ Cho] at P < .01). Correlation between the individual NAA ratios and the FA values was moderate (r = 0.53 [NAA/Cr], 0.51 [NAA/Cho] at P < .01). CONCLUSION: In gliomas, the degree of tissue organization decreases continuously from the surrounding tissue toward the center of the tumor accompanied by a concordant decrease of NAA. This uniform behavior of FA and NAA reflects a decreasing integrity of both neuronal structures and fibers.     

Proton MR spectroscopic and diffusion tensor brain MR imaging in X-linked adrenoleukodystrophy: initial experience

PURPOSE: To compare conventional magnetic resonance (MR) imaging, proton MR spectroscopic imaging, and diffusion tensor (DT) MR imaging findings in patients with X chromosome-linked adrenoleukodystrophy (X-ALD). MATERIALS AND METHODS: Multisection proton MR spectroscopy and DT imaging were performed in 11 patients with X-ALD and in 11 healthy control subjects. Quantitative measures of N-acetylaspartate (NAA), choline, and creatine values and of isotropic apparent diffusion coefficient (IADC) and fractional anisotropy (FA) were obtained from coregistered regions of interest. DT imaging and metabolic parameters were compared by using regression analysis. In addition, differences in DT imaging and metabolite measurements between normal- and abnormal-appearing white matter on conventional MR images were evaluated by using a nonparametric (Mann-Whitney) test. RESULTS: A strong logarithmic relationship between NAA value and FA (r = 0.64, P <.001) and an inverse logarithmic relationship were found between NAA value and IADC (r = -0.69, P <.001). Creatine and choline values correlated poorly with IADC and FA. In the normal-appearing white matter of asymptomatic patients, the NAA value was 17% lower than that in the healthy control subjects (P =.016), whereas no significant difference in DT imaging measures was seen in these regions. CONCLUSION: In patients with X-ALD, MR spectroscopic imaging can depict abnormalities in white matter that have a normal appearance on both conventional MR and DT images; this finding suggests that it may be the most sensitive technique for detecting early abnormalities of demyelination or axonal loss in patients with X-ALD.     

Brain MR spectroscopy findings in neonates with hypothyroidism born to mothers living in iodine-deficient areas

BACKGROUND AND PURPOSE: Iodine deficiency and hypothyroxinemia have a negative effect on the development of the central nervous system during fetal and early postnatal life. MR spectroscopy is a sensitive technique for detecting the changes of brain metabolites in various neurodevelopmental disorders. By using MR spectroscopy, we aimed to show the decrease in N-acetylaspartate (NAA) levels in neonates with hypothyroidism who were born in iodine-deficient areas and its normalization with early thyroxine therapy. METHODS: Eight congenital hypothyroid and 8 healthy full-term neonates were chosen as study and control groups, respectively. Serum thyroid hormones and median urinary iodine concentration of the neonates and their mothers were measured. Measurements of NAA, choline (Cho), and creatine (Cr) were made in frontal white matter, parietal white matter (PWM), and the thalamus with MR spectroscopy, first at 5-7 days of life and after 8 weeks of thyroxine therapy in the study group and at the same time in the control group. RESULTS: The patient group had significantly lower NAA/Cr ratios in PWM and the thalamus (P < .05, for each), whereas the difference between Cho/Cr ratios of the 2 groups before therapy was not significant. After 8 weeks of thyroxine therapy, measurements did not show significant difference between study and control groups. CONCLUSION: MR spectroscopy performed in neonates with hypothyroidism reveals that intrauterine hypothyroxinemia due to iodine deficiency results in significant decrease in NAA levels in PWM and the thalamus and that the normalization of NAA levels is achieved with early thyroxine therapy.     

Proton MR spectroscopy in Wilson disease: analysis of 36 cases

BACKGROUND AND PURPOSE: Wilson disease (WD) is rare but one of the few metabolic disorders that can possibly benefit from effective available treatments. The literature regarding proton MR spectroscopy (MRS) in WD is scarce and controversial. The purpose of this study was to determine the brain metabolic changes due to WD by using MRS. To our knowledge, this is the first time that MRS was performed in such a large sample of patients with WD. METHODS: Thirty-six patients with WD and 37 healthy volunteers were examined with MRS in the parieto-occipital cortex, frontal white matter, and basal ganglia (BG). Ratios of the following metabolites were calculated in relation to creatine (Cr): N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), and glutamine/glutamate (Glx). The mean peak line width was measured on each spectrum. RESULTS: Compared with control subjects, patients with WD had significantly decreased NAA/Cr ratios in the three studied areas (P < .005) and an increased mI/Cr ratio in the BG (P < .001). Cho/Cr and Glx/Cr did not differ between the groups. The mean peak line in the BG was wider in patients than in control subjects. CONCLUSION: WD is unequivocally associated with MRS changes that could possibly be assigned to neuronal loss (in the three studied areas), to gliosis, and to iron and/or copper deposition in the BG.     

High spatial resolution 1H-MRSI and segmented MRI of cortical gray matter and subcortical white matter in three regions of the human brain.

High-resolution MR imaging and spectroscopic imaging were used to study differences in proton spectra between cortical gray matter and subcortical white matter in 23 normal volunteers using a 1.5 T scanner and surface coil receivers. A point-resolved spectroscopy (PRESS) volume with an 8 x 8 x 8 phase-encoding matrix was used to acquire over 1900 0.09-0.2 cc spectral voxels. The high-resolution (0.7 x 0.7 x 0.8 mm3 or 0.8 x 0.8 x 1 mm3) images were corrected for the surface coil reception profile and segmented into cerebrospinal fluid (CSF) and gray and white matter to correlate with the spectra. The data showed that N-acetyl aspartate (NAA) and creatine (Cr) were higher in the gray matter than in the white matter (NAA(g/w) = 1.4+/-0.36, Cr(g/w) = 1.4+/-0.41). Choline was significantly lower in the gray matter of the occipital lobe than in the white matter (0.73+/-0.19), but not significantly different in the other regions. NAA/Cho was found to be significantly higher in the occipital lobe than in the left frontal or vertex regions.     

Multisection proton MR spectroscopy for mesial temporal lobe epilepsy

BACKGROUND AND PURPOSE: Extensive metabolic impairments have been reported in association with mesial temporal lobe epilepsy (mTLE). We investigated whether proton MR spectroscopy ((1)H-MRS) depicts metabolic changes beyond the hippocampus in cases of mTLE and whether these changes help lateralize the seizure focus. METHODS: MR imaging and (1)H-MRS were performed in 15 patients with mTLE with a postoperative diagnosis of mesial temporal sclerosis and in 12 control volunteers. Point-resolved spectroscopy and multisection (1)H-MRS measured N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the hippocampus, temporal opercular and lateral cortices, insula and cerebellum, and frontal, parietal, and occipital lobes. Metabolites were assessed as ratios to Cr and in absolute units. RESULTS: Twelve patients had ipsilateral hippocampal atrophy; three had negative imaging results. In the ipsilateral hippocampus, absolute NAA (/NAA/) was 27.3% lower in patients compared with that in control volunteers (P <.001) and 18.5% lower compared with that in the contralateral side (P <.01). /NAA/ averaged over selected regions in the ipsilateral temporal lobes of patients with mTLE was 19.3% lower compared with the mean in the control group (P <.0001) and by 17.7% lower compared with the contralateral values (P <.00001). Using only hippocampal data, 60% of the cases of mTLE were correctly lateralized. Lateralization, determined using whole temporal lobe data, had 87% sensitivity and 92% specificity. /NAA/ was bilaterally reduced in the frontal, parietal, and occipital lobes of patients with mTLE compared with that in control volunteers (P <.01). CONCLUSION: Multisection (1)H-MRS depicts interictal reductions of NAA in the ipsilateral temporal lobe beyond the hippocampus and accurately lateralizes seizure foci.     

Proton MR spectroscopy of the cerebellum and pons in patients with degenerative ataxia

PURPOSE: To investigate whether proton magnetic resonance (MR) spectroscopy is a useful complement to MR imaging in patients with degenerative ataxia. MATERIALS AND METHODS: Brain MR imaging and single-voxel proton MR spectroscopy of the right cerebellar hemisphere and pons were performed in 30 patients with sporadic (n = 16) or inherited (n = 14) degenerative ataxia and in 20 healthy control subjects. Several indexes of brainstem and cerebellar atrophy were measured on MR images, as well as the N-acetylaspartate/creatine (NAA/Cr), choline/Cr (Cho/Cr), and myo-inositol/Cr (mI/Cr) ratios in the MR spectra. Differences between patients and subjects were evaluated with the Kruskal-Wallis and Mann-Whitney tests, whereas correlation of clinical, MR imaging, and spectroscopic data was assessed with nonparametric Spearman rank correlation. RESULTS: Measurements of brainstem and cerebellar atrophy obtained from MR images revealed patients had olivopontocerebellar atrophy (OPCA) (n = 11), spinal atrophy (SA) (n = 8), or corticocerebellar atrophy (CCA) (n = 4). Seven patients did not fulfill the criteria for any group and were considered undefined. In patients with OPCA, the pontine and cerebellar NAA/Cr and Cho/Cr ratios were significantly decreased when compared with those of the control subjects. Pontine and cerebellar NAA/Cr ratios were also significantly reduced in patients with SA and CCA. Five patients with undefined ataxia had a substantial decrease of pontine or cerebellar NAA/Cr ratio when compared with that of the control subjects. In patients with OPCA, the pontine NAA/Cr ratio (but not the atrophy measurements) showed a correlation (P =.04) with disability. CONCLUSION: MR spectroscopy is a useful complement to MR imaging in patients with degenerative ataxia.