Volume correction for edema in single-volume proton MR spectroscopy of contrast-enhancing multiple sclerosis lesions.

The effect of edema on metabolic changes in contrast-enhancing multiple sclerosis lesions was studied by combining quantification of proton MR spectra with segmentation of the volume-of-interest, which was based on biexponential T(2) relaxation. All lesions showed a second component (s(long)) with a longer T(2) (185-450 ms), which was increased compared to healthy controls. Regression analysis indicated that s(long) replaces the short-T(2) component and total creatine. Since the water content was close to 100%, s(long) was used to correct for an increase in extracellular space. This compensated for the apparent loss of creatine and rendered cholines markedly increased, as observed in animals with experimental allergic encephalomyelitis. Total N-acetyl aspartate (NAA) concentration was inversely correlated with s(long) and between 34-70% of its average reduction was assigned to edema. Thus, NAA loss exceeded cellular loss. Assessment of varying degrees of edema may be especially beneficial for quantitative longitudinal studies.     

Proton MR spectroscopy of gadolinium-enhanced multiple sclerosis plaques.

Magnetic resonance (MR) imaging and proton MR spectroscopy were performed in 14 patients with clinically definite multiple sclerosis (MS). Prominent resonances in the 0.5-2.0-ppm region were seen in the spectra of six of nine gadopentetate dimeglumine-enhanced plaques in seven patients. These resonances were presumed to originate in lipids and other myelin breakdown products. Similar resonances were detected in only seven of 21 unenhancing plaques. The more frequent presence of such signals in the gadolinium-enhanced regions indicates that myelin breakdown is often associated with the inflammation that occurs in early stages of MS plaque evolution. It remains uncertain, however, whether active inflammation as indicated by gadolinium enhancement is a necessary precursor of myelin breakdown as detected at MR spectroscopy. Quantitative spectral analysis did not indicate statistically significant differences in N-acetyl aspartate and choline levels relative to creatine plus phosphocreatine between healthy volunteers and MS patients.     

Human brain proton localized NMR spectroscopy in multiple sclerosis

Localized proton spectroscopy of the brain was performed on MS patients (n = 18) and the results are compared with those of a control group (n = 17). The experiments were performed in a 1.5-T Siemens Magnetom using the stimulated echo method and selective water suppression. Acquisition parameters were TR/TE/TM = 3000/270/30 ms, NA = 256, and Acq = 13 min. Localized volumes ranged from 8 to about 80 cc. The patients (ages 25 to 66) were at various stages of the disease. Three of the eighteen patients did not show any plaques on the MR images. VOIs were chosen to contain as much plaque volume as possible in the cerebrum white matter. In the controls and in the patients with no plaques, the VOI were localized in similar white matter regions. All spectra were characterized by the presence of Cho (3.2 ppm), PCr + Cr (3.0 ppm), and NAA (2.0 ppm). The ratios NAA/Cho and NAA/(PCr + Cr) were calculated for both the MS and the control group. The results for the three MS patients with no detectable plaques did not differ significantly from the results of the control group. The former group is, however, too limited to draw any conclusion for the moment. For the MRI positive patients, the following values were found (means +/- 1 SD); NAA/Cho = 1.98 +/- 0.33 and NAA/(PCr + Cr) = 2.16 +/- 0.14. In the normals, these values were NAA/Cho = 2.54 +/- 0.39 and NAA/(PCr + Cr) = 2.76 +/- 0.25. The results quoted are TR and TE dependent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Infantile tuberous sclerosis changes in the brain: proton MR spectroscopy findings.

A parietal hamartoma of a three-month-old boy with tuberous sclerosis was studied with magnetic resonance (MR) imaging, and proton MR spectroscopy. MR spectra were obtained with the single-voxel PRESS (point resolved spectroscopy; TR = 1500 ms, TE = 135 ms) sequence, in a 8 cc region of interest. Apparently low NAA/Cho (0.28), and NAA/Cr (0.37) ratios were noted in the hamartoma, that could suggest a neoplasm. The lesion and the surrounding brain tissue were studied again after seven months with spectroscopic imaging using the chemical shift sequence (TR = 1500 ms. TE = 40 ms). This study revealed apparently improved NAA/Cho (2.63), NAA/Cr (2.13) ratios in the hamartoma compared to the initial examination at three months of age, excluding the possibility of a neoplasm.     

Benign versus secondary-progressive multiple sclerosis: the potential role of proton MR spectroscopy in defining the nature of disability.

PURPOSEWe determined the clinical utility of proton MR spectroscopy in defining the extent of disability in benign versus secondary-progressive multiple sclerosis (MS).METHODSThirty patients with clinically definite MS, including 16 patients with benign MS and 14 with secondary-progressive MS, and a group of 13 healthy volunteers were studied with combined stimulated-echo acquisition mode proton MR spectroscopy and MR imaging (all patients received contrast material).RESULTSAcute enhancing lesions of benign and secondary-progressive MS were characterized by a reduction in N-acetylaspartate (NAA)/choline and NAA/creatine and an increase in inositol compounds/creatine as compared with normal white matter. Such variations were also detected in chronic unenhancing lesions in patients with secondary-progressive MS, although they were not found in chronic unenhancing lesions in patients with benign MS. Chronic lesions of the two forms of the disease have significative differences in NAA and inositol signals.CONCLUSIONProton MR spectroscopy is able to show metabolic changes occurring in the white matter of patients with MS. Such changes differ according to the phase (acute versus chronic) and the clinical form (benign versus secondary-progressive) of the disease.     

Localized in vivo proton spectroscopy in the brain of patients with multiple sclerosis.

Localized proton spectroscopy was performed in 15 patients with acute or chronic multiple sclerosis (MS). Some of the patients were investigated serially, being given a total of 22 spectroscopic investigations. Resonances corresponding to free lipids were observed in six plaques. This was distinctly seen in two plaques at Days 70 and 85 after the occurrence of the plaques. A lesser content of lipids in plaques was observed as early as Day 10 and as late as nearly 1 year after occurrence. The relative concentration of N-acetyl asparate (NAA) was significantly lower in patients than in controls, and the relative concentration of choline (Cho) was significantly higher in patients than in controls. These differences were most pronounced in older plaques. MR spectroscopic demonstration of lipids in a MS plaque probably reflects disintegration of myelin, and a decreased NAA/Cho ratio may be related either to gliosis or to axonal degeneration, which sometimes occurs in longstanding MS.     

MR spectroscopy of cervical spinal cord in patients with multiple sclerosis

MR spectroscopy (MRS) of the brain in patients with multiple sclerosis has been well studied. However, in vivo MRS of the spinal cord in patients with MR spectroscopy has not been reported to our knowledge. We performed MRS of normal-appearing cervical spinal cords in multiple sclerosis patients and in healthy controls. N-acetyl aspartate was shown to be reduced within the cervical spinal cord of multiple sclerosis patients when compared with healthy controls. This finding supports axonal loss and damage within even normal-appearing spinal cords of multiple sclerosis patients.An erratum to this article can be found at     

Metachromatic leukodystrophy. Diffusion MR imaging and proton MR spectroscopy

Metachromatic leukodystrophy is characterized by dysmyelination caused by a deficiency of arylsulfatase-A. In a 17-month-old boy with metachromatic leukodystrophy, an echo-planar diffusion MR sequence revealed a restricted diffusion pattern in the deep white matter, manifested by high-signal on b = 1000 s/mm² images, and low ADC values (0.56 × 10^-3 mm²/s). Proton MR spectroscopy revealed a marked decrease in choline, a metabolite related to myelin turnover. These observations consisting of a restricted diffusion pattern on diffusion MR imaging, and decreased choline peaks on proton spectroscopy, likely represented dysmyelination in metachromatic leukodystrophy.     

Human brain infarction: proton MR spectroscopy.

Two-dimensional proton magnetic resonance (MR) spectroscopic imaging studies were performed of the distributions of the major hydrogen-1 metabolites of choline, creatine, N-acetyl aspartate (NAA) and lactate in normal (n = 6) and subacutely to chronically infarcted (n = 10) human brain. The two dimensions of phase encoding were applied over a 20-mm-thick section of brain tissue that had been selected with a double spin-echo localization method. Normal brain showed bilaterally symmetric metabolite distributions and no detectable lactate. Nine of 10 studies of brain infarction showed substantial decreases in NAA, creatine, and choline in the infarcted area compared with control areas; averaged for all studies, the decreases were 77% +/- 8, 63% +/- 11, and 54% +/- 12, respectively (mean +/- standard error). The decreased metabolite concentrations are probably due primarily to diminished cell density in the infarct. The decrease in NAA was larger than the decreases in choline and creatine. Findings in all of the studies showed lactate in the infarcted tissue and/or ventricles. The continued presence of lactate in the infarct indicates increased anaerobic glycolysis due to ischemia or other factors.     

MR imaging and localized proton spectroscopy of the precentral gyrus in amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE: In the search for a diagnostic test for amyotrophic lateral sclerosis (ALS), especially upper motor neuron (UMN) involvement, MR imaging and proton spectroscopy techniques have each received attention, but their findings have not been correlated. The purpose of this study was to identify relationships among the results of current techniques, taking into account the severity of clinical UMN disease, so that objective measures of the pathogenesis of ALS may be established. METHODS: Eighteen subjects with clinically diagnosed ALS and 12 healthy volunteers underwent MR imaging of the brain and localized proton MR spectroscopy. Water-suppressed spectra from the left precentral gyrus and from the left cuneus gyrus were analyzed with the LCModel method, yielding concentrations for N-acetyl (NA), total creatine (Cr), choline (Cho), glutamate (Glu), glutamine (Gin), and myo-inositol (Ins) metabolic substrates. Signal intensities of the precentral gyrus on T2-weighted images were assessed qualitatively in a blinded fashion. RESULTS: For the precentral gyrus, mean Cho (1.3 mM) and Ins (3.25 mM) for the ALS group were significantly increased. After adjustment for Cr covariance, mean Glu (5.08 mM) and NA (6.31 mM) were decreased. For the cuneus gyrus, no difference in metabolite concentrations between groups was observed. Trend analysis of the precentral gyrus metabolite concentrations revealed significant increases in Cho and Ins and decreases in NA and Glu with respect to the severity of clinical UMN signs. Metabolic changes were greater in the subset of ALS patients with precentral gyrus signal changes on imaging, and significantly increased Ins was associated with cortical hypointensity on fast spin-echo images. CONCLUSION: Mean metabolite concentrations determined from precentral gyrus spectra reflect clinical and pathologic changes that occur in ALS. Imaging findings, while related to the spectral and clinical results, are not specific to ALS.     

磁共振波谱技术在乳腺癌诊断中的应用

目的:利用氢质子磁共振波谱(1H MRS)技术检测活体乳腺癌病灶与对侧正常乳腺组织内的物质代谢和物质生化含量的差异及其反映在分子水平上的病理改变。方法:对30例经乳腺钼靶摄影疑为一侧乳腺癌的患者行1H MRS检查,比较其病侧与对侧相应部位正常腺体组织的胆碱(Choline,Cho)、乳酸(Lactine,Lac)含量有无显著性差异。结果:正常乳腺组织1H MRS在1.32ppm处显示一独立清晰的乳酸峰,胆碱峰显示低平,Cho峰顶与Lac峰顶的连线呈上升趋势。30例病侧组在3.2ppm处Cho峰显著增高,Lac峰明显降低,Cho峰顶与Lac峰顶的连线呈下降趋势;两组间行秩和检验,差异有显著性(P<0.05)。结论:氢质子磁共振波谱(1H MRS)对于乳腺癌的定性诊断可提供有价值的辅助信息。     

MR imaging and proton MR spectroscopy in adult Krabbe disease

We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical presentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2-weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother. Proton MR spectroscopy showed increased choline and myo-inositol in the affected white matter. In the second family, the clinical presentation differed in that the signs of pyramidal tract involvement were asymmetrical, with concomitant asymmetry on MR images in one. In adults, Krabbe disease may present on MR imaging with selective pyramidal fiber involvement.     

Serial proton MR spectroscopy of contrast-enhancing multiple sclerosis plaques: absolute metabolic values over 2 years during a clinical pharmacological study

BACKGROUND AND PURPOSE: The time courses of total creatine (Cr), N-acetylaspartate (NAA), choline (Cho), and myo-inositol have not previously been investigated in the follow-up of contrast-enhancing multiple sclerosis (MS) plaques. Therefore, over a period of 2 years, we compared the absolute concentrations of these metabolites between patients treated with a placebo or 15 +/- deoxyspergualin (DSG) and between clinical groups with relapsing-remitting or secondary-progressive MS. METHODS: Sixteen patients, recruited from a pharmacological study of DSG, and 11 healthy control subjects were investigated by a stimulated-echo acquisition mode sequence (TR/TE = 3000/20). The selected volume initially contained a contrast-enhancing plaque, which was followed up for a period of 2 years. RESULTS: In contrast-enhancing plaques, Cho was significantly elevated and showed a significant reduction after both 3 and 12 months. The initially normal Cr significantly increased between 3 and 12 months, and was negatively correlated with plaque volume on T1-weighted MR images. NAA initially showed normal values, a significant decrease at 1 month, and a slow recovery over 2 years. Myo-inositol did not show a clear tendency. The placebo group did not differ from the treated group, nor did the relapsing-remitting group differ from the secondary-progressive group. CONCLUSION: The contradictory time courses of Cr and NAA show that an absolute quantification in proton MR spectroscopy in MS is necessary to avoid a false interpretation of reduced NAA/Cr ratios. The increase in Cr is probably due to remyelination. The initial dip and later recovery of NAA seem to be related to diminishing edema and remyelination.     

Quantitative MR in the diagnosis of multiple sclerosis.

In patients with multiple sclerosis (MS), the apparently uninvolved cerebral white matter between demyelinated plaques may have biochemical abnormalities. To what degree the changes in the white matter contribute to symptomatology in MS is unknown. In 39 patients with multiple sclerosis, and in 39 age-matched nondiseased volunteers, T1 and T2 were calculated from spin-echo images in four regions of apparently uninvolved white matter. In three of four white matter areas, the average T1 and T2 were significantly longer in the patients than in the controls. The T1 correlated with the disability, measured by the Kurtzke Extended Disability Status Scale, although the correlation was marginally significant. The results suggest that in patients with MS, white matter disease that is not visualized in MR as distinct foci of abnormal signal intensity may contribute to disease burden and disability.     

MR venography of multiple sclerosis

BACKGROUND AND PURPOSE: The distribution of multiple sclerosis (MS) lesions in the brain follows a specific pattern, with most lesions in the periventricular regions and in the deep white matter; histopathologic studies have shown a perivenous distribution. The aim of this study was to illustrate these distribution patterns in vivo using high-resolution MR venography. METHODS: Seventeen MS patients underwent MR imaging at 1.5 T. Venographic studies were obtained with a 3D gradient-echo technique. MS lesions were identified on T2-weighted images, and their shape, orientation, and location were compared with the venous anatomy on the venograms. RESULTS: The use of contrast material facilitated the visualization of small veins and increased the number of veins seen. A total of 95 MS lesions could be identified on both the T2-weighted series and the venograms; a central vein was visible in all 43 periventricular lesions and in all but one of the 52 focal deep white matter lesions. The typical ovoid shape and orientation of the long axis of the MS lesions correlated well with the course of these veins. CONCLUSION: With MR venography, the perivenous distribution of MS lesions in the brain can be visualized in vivo. The venous anatomy defines the typical form and orientation of these lesions.     

MR imaging of multiple sclerosis

Owing to its ability to depict the pathologic features of multiple sclerosis (MS) in exquisite detail, conventional magnetic resonance (MR) imaging has become an established tool in the diagnosis of this disease and in monitoring its evolution. MR imaging has been formally included in the diagnostic work-up of patients who present with a clinically isolated syndrome suggestive of MS, and ad hoc diagnostic criteria have been proposed and are updated on a regular basis. In patients with established MS and in those participating in treatment trials, examinations performed with conventional MR pulse sequences provide objective measures to monitor disease activity and progression; however, they have a limited prognostic role. This has driven the application of newer MR imaging technologies, including higher-field-strength MR units, to estimate overall MS burden and mechanisms of recovery in patients at different stages of the disease. These techniques have allowed in vivo assessment of the heterogeneity of MS pathologic features in focal lesions and in normal-appearing tissues. More recently, some of the finer details of MS, including macrophage infiltration and abnormal iron deposition, have become quantifiable with MR imaging. The utility of these modern MR techniques in clinical trial monitoring and in the assessment of the individual patient's response to treatment still need to be evaluated.     

MR imaging and localized proton MR spectroscopy in late infantile neuronal ceroid lipofuscinosis.

PURPOSELate juvenile neuronal ceroid lipofuscinosis (NCL) is a lysosomal neurodegenerative disorder caused by the accumulation of lipopigment in neurons. Our purpose was to characterize the MR imaging and spectroscopic findings in three children with late infantile NCL.METHODSThree children with late infantile NCL and three age-matched control subjects were examined by MR imaging and by localized MR spectroscopy using echo times of 135 and 5. Normalized peak integral values were calculated for N-acetylaspartate (NAA), choline, creatine, myo-inositol, and glutamate/glutamine.RESULTSMR imaging revealed volume loss of the CNS, most prominently in the cerebellum. The T2-weighted images showed a hypointense thalamus and hyperintense periventricular white matter. Proton MR spectra revealed progressive changes, with a reduction of NAA and an increase of myo-inositol and glutamate/glutamine. In long-standing late infantile NCL, myo-inositol became the most prominent resonance. Lactate was not detectable.CONCLUSIONMR imaging in combination with proton MR spectroscopy can facilitate the diagnosis of late infantile NCL and help to differentiate NCL from other neurometabolic disorders, such as mitochondrial or peroxisomal encephalopathies.