Proton MR spectroscopy of Wernicke encephalopathy

Two patients with acute thiamine deficiency were examined with thalamic single-voxel proton MR spectroscopy. T2-weighted images exhibited increased signal intensity. N-acetylaspartate (NAA)/creatine (Cr) ratios were low without detectable lactate. Owing to substantially decreased choline (Cho) T2, the Cho/Cr ratio was not decreased. After thiamine therapy, the NAA/Cr ratio increased, paralleling clinical improvement and reduction in the areas of signal-intensity changes.     

Proton MR spectroscopy of craniopharyngiomas.

To date, only a few cases of craniopharyngiomas have been studied by magnetic resonance (MR) spectroscopy. We report our spectroscopy experiences with five patients having surgically proven craniopharyngiomas. Proton MR spectroscopy images were obtained using the single-voxel mode with spin-echo point resolved spectroscopy. Very prominent peaks centered at 1-1.5ppm were noted in spectroscopic analysis, which probably corresponded to lipid/cholesterol peaks, correlating with the histological findings revealing high amounts of cholesterol in the cyst fluids.     

Proton MR spectroscopy of the prostate

PURPOSE: To summarize current technical and biochemical aspects and clinical applications of proton magnetic resonance spectroscopy (MRS) of the human prostate in vivo. MATERIAL AND METHODS: Pertinent radiological and biochemical literature was searched and retrieved via electronic media (medline, pubmed. Basic concepts of MRS of the prostate and its clinical applications were extracted. RESULTS: Clinical MRS is usually based on point resolved spectroscopy (PRESS) or spin echo (SE) sequences, along with outer volume suppression of signals from outside of the prostate. MRS of the prostate detects indicator lines of citrate, choline, and creatine. While healthy prostate tissue demonstrates high levels of citrate and low levels of choline that marks cell wall turnover, prostate cancer utilizes citrate for energy metabolism and shows high levels of choline. The ratio of (choline+creatine)/citrate distinguishes between healthy tissue and prostate cancer. Particularly when combined with magnetic resonance (MR) imaging, three-dimensional MRS imaging (3D-CSI, or 3D-MRSI) detects and localizes prostate cancer in the entire prostate with high sensitivity and specificity. Combined MR imaging and 3D-MRSI exceed the sensitivity and specificity of sextant biopsy of the prostate. When MRS and MR imaging agree on prostate cancer presence, the positive predictive value is about 80-90%. Distinction between healthy tissue and prostate cancer principally is maintained after various therapeutic treatments, including hormone ablation therapy, radiation therapy, and cryotherapy of the prostate. CONCLUSIONS: Since it is non-invasive, reliable, radiation-free, and essentially repeatable, combined MR imaging and 3D-MRSI of the prostate lends itself to the planning of biopsy and therapy, and to post-therapeutic follow-up. For broad clinical acceptance, it will be necessary to facilitate MRS examinations and their evaluation and make MRS available to a wider range of institutions.     

Proton MR spectroscopy in clinical routine

In vivo magnetic resonance spectroscopy (MRS) addresses metabolic pathways and their steady states in different tissue types. The brain has by tradition, and due to technical limitations in other organs, been one of the tissues most studied by MRS, and both 1H- and 31P-MRS have been used. Although 31P-MRS is outstanding for the evaluation of sources of metabolic energy in the brain, 1H-MRS has become the major clinically applied method in neurospectroscopy, as it provides information on markers of neuronal function, myelin, cell membranes, and metabolic active compounds. Furthermore, MR sensitivity is much greater for protons than it is for phosphorus and 1H-MRS, therefore allowing better spatial resolution. This review focuses on neurospectroscopy and diagnostic insights into diverse neurological problems provided by 1H-MRS applied as a clinical tool.     

Proton MR spectroscopy in gliomatosis cerebri

Two cases of gliomatosis cerebri are presented in which there was markedly decreased N-acetyl aspartate and an elevated lactate-lipid area in the MR proton spectra. Received: 6 September 1999 Accepted: 10 December 1999     

Proton MR spectroscopy in Wernicke encephalopathy

Wernicke encephalopathy is caused by thiamine deficiency. Although the clinical picture has been well established for some time, clinical diagnosis is attained in only 20% of the cases. MR imaging techniques contribute to early diagnosis of Wernicke encephalopathy. We herein report MR imaging and proton MR spectroscopic findings for a patient with clinical and biochemical features consistent with Wernicke encephalopathy. Increased lactate and typical MR imaging findings are discussed in the context of the known pathophysiology of Wernicke encephalopathy.     

Proton MR spectroscopy of tumefactive demyelinating lesions

BACKGROUND AND PURPOSE: Tumefactive demyelinating lesions (TDLs) can simulate intracranial neoplasms in clinical presentation and MR imaging appearance, and surgical biopsy is often performed in suspected tumors. Proton MR spectroscopy has been applied in assessing various intracranial diseases and is increasingly used in diagnosis and clinical management. Our purpose was to determine if multivoxel proton MR spectroscopy can be used to differentiate TDLs and high-grade gliomas. METHODS: Conventional MR images, proton MR spectra, and medical records were retrospectively reviewed in six patients with TDLs diagnosed by means of biopsy or by documented clinical improvement, with or without supporting laboratory testing and follow-up imaging. Proton MR spectra of 10 high-grade gliomas with similar conventional MR imaging appearances were used for comparison. In contrast-enhancing, central, and perilesional areas of each lesion, peak heights of N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) were measured and the lactate peak noted. Cho/Cr and NAA/Cr ratios of corresponding regions in TDLs and gliomas were compared. RESULTS: No significant differences in mean Cho/Cr ratios were found in the corresponding contrast-enhancing, central, or perilesional areas of TDLs and gliomas. The mean central-region NAA/Cr ratio in gliomas was significantly lower than that of TDLs, but mean NAA/Cr ratios in other regions were not significantly different. A lactate peak was identified in four of six TDLs and three of 10 gliomas. CONCLUSION: In the cases examined, the NAA/Cr ratio in the central region of TDLs and high-grade gliomas differed significantly. However, overall metabolite profiles of both lesions were similar; this finding emphasizes the need for the cautious interpretation of spectroscopic findings.     

Proton MR spectroscopy in Lesch-Nyhan disease.

In vivo proton spectra for four patients with Lesch-Nyhan disease and four control subjects matched for age and sex were acquired from voxels (1.5 x 1.5 x 1.5 cm3) placed in the prefrontal cortex and striatum. The patients with Lesch-Nyhan disease had decreased metabolites, especially N-acetylaspartate and glutamate/glutamine, only in the prefrontal cortex as compared with the control group. These findings suggest axonal loss in the prefrontal area of this population. The cortical glutamate/glutamine peak decrement does not confirm cytopathologic studies of Lesch-Nyhan disease and deserves further investigation.     

Proton MR spectroscopy in idiopathic spasmodic torticollis

Single-voxel proton magnetic resonance spectroscopy (¹H-MRS), localised to the basal ganglia, was used to determine changes in metabolite levels in idiopathic spasmodic torticollis (IST). We examined nine patients and 13 healthy subjects. The mean values ( ± SD) of peak area ratios were: IST: N-acetyl-aspartate (NAA)/choline-containing compounds (Cho) 1.79 ± 0.39, NAA/creatine and phosphocreatine compounds (Cr) 1.61 ± 0.38, Cho/Cr 0.91 ± 0.19; controls: NAA/Cho 2.07 ± 0.35, NAA/Cr 1.82 ± 0.31, Cho/Cr 0.89 ± 0.12. Statistical analysis showed that NAA/Cho and NAA/Cr were significantly lower in patients than in controls (P = 0.0304 and 0.0431, respectively). These results indicate a reduction in NAA, and suggest striatal involvement in the pathogenesis IST. Received: 8 October 2000 Accepted: 4 December 2000     

Proton MR spectroscopy in Rett syndrome.

Seven patients (mean age 7.7yr) with Rett syndrome, a condition with progressive regression of psychomotor development are included in this study. Proton MR spectroscopy images were obtained with the multivoxel chemical-shift imaging mode (TR=1500ms, TE=40ms). Spectra from 224 voxels in the brain parenchyma were studied. N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), and myoinositol (mI) peaks were quantitatively evaluated, and NAA/Cr, NAA/Cho, and Cho/Cr, mI/Cr ratios were calculated. Five age-matched normal cases were available as controls. In three patients with Rett syndrome spectroscopy findings were normal, and the metabolite ratios were similar to control cases. In the remaining four patients with the syndrome prominent decrease of the NAA peak was the main finding resulting in decreases in NAA/Cr (1.14+/-17), and NAA/Cho (1.08+/-27) ratios (p<0.0001). Cho/Cr ratios (0.93+/-26), and mI/Cr ratios (0.88+/-36) were normal compared to controls. There was no correlation between spectroscopic changes and clinical status of the patients. The findings suggested that not only reduced neuronal-dendritic arborizations but also decreased neuronal function could contribute to spectroscopy changes in Rett syndrome.     

Proton MR spectroscopy in Coats disease.

We describe a case of acute left-sided visual loss in a 4-year-old boy. CT showed hyperdense retinal detachment with a tiny calcification, and MR imaging showed subretinal hyperintensity on both T1- and T2-weighted images. Proton MR spectroscopy showed a large peak between 1 and 1.6 ppm that we believe corresponds mainly to lipids, which are characteristic of the exudate present in Coats disease.     

Proton MR spectroscopy in Pelizaeus-Merzbacher disease.

Proton MR spectroscopic findings in two patients with genetically defined Pelizaeus-Merzbacher disease revealed ratios of N-acetylaspartate/creatine and choline-containing compounds/creatine that were not significantly different from those found in a population of healthy subjects. These findings suggest that proton MR spectroscopy can aid in the diagnosis of Pelizaeus-Merzbacher disease.     

Proton MR spectroscopy of adult-onset dentatorubral-pallidoluysian atrophy.

PURPOSE: To quantify impairment of the basal ganglia (globus pallidus and thalamus) in adult-onset dentatorubral-pallidoluysian atrophy (DRPLA). METHODS: Five patients with genetically definite adult-onset DRPLA (aged 51 to 65 years, mean 55.6 years) and 5 age- and sex-matched healthy controls underwent conventional magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) of the brain in the voxels predominantly containing the globus pallidus or the thalamus. RESULTS: Conventional MRI studies showed apparently normal intensities in the globus pallidus and thalamus. MRS showed that the choline (Cho)/creatine (Cr) ratio for the patients' globus pallidus, the region preferentially affected in DRPLA, was significantly higher than that in the controls (p<0.05). The N-acetylaspartate (NAA)/Cr ratio for the globus pallidus and the Cho/Cr and NAA/Cr ratios for the thalamus, the region relatively spared in this disease, did not differ significantly between the patients and controls. CONCLUSIONS: MRS may sensitively and specifically detect biochemical alterations in susceptible regions of patients with adult-onset DRPLA.     

Proton MR spectroscopy of pediatric cerebellar tumors.

PURPOSETo investigate the role of proton MR spectroscopy in pediatric cerebellar tumor diagnosis.METHODSSingle voxel pulse sequences with long echo time (135 or 270 milliseconds, voxel size 8 to 19 cm3), were used to obtain proton spectra of primary pediatric cerebellar tumors. Eleven primitive neuroectodermal tumors (patient age, 2 to 12 years; mean, 7 years), 11 low-grade astrocytomas (age, 2 to 16 years; mean, 9 years), 4 ependymomas (age, 1 to 6 years; mean, 4 years), 1 mixed glioma ependymo-astrocytoma (age, 11 years), 1 anaplastic ependymoma (age, 7 years), 1 ganglioglioma (age, 14 years), and 1 malignant teratoma (age, 6 days) were studied. Control cerebellum spectra were acquired from five patients without abnormality in cerebellum (age, 2 to 15 years; mean, 8 years). The signal intensities from choline-containing compounds (Cho), creatine/phosphocreatine (Cr), N-acetyl-aspartate (NAA), and lactate (Lac) were quantified. The mean and standard deviation of metabolite ratios were calculated.RESULTSThe control spectra ratios (NAA:Cho = 1.49 +/- 0.36, Cr:Cho = 1.13 +/- 0.23) were distinct from the tumor spectra (NAA:Cho = 0.41 +/- 0.27 and Cr:Cho = 0.37 +/- 0.23). Most of primitive neuroectodermal tumors had low NAA:Cho (0.17 +/- 0.09) and Cr:Cho (0.32 +/- 0.19). Compared with primitive neuroectodermal tumors, low-grade astrocytomas and ependymomas had higher NAA:Cho ratio (0.63 +/- 0.19 and 0.39 +/- 0.12). The Cr:Cho ratio was higher for ependymomas (0.60 +/- 0.20) than for astrocytomas (0.27 +/- 0.12) and primitive neuroectodermal tumors. No NAA was found in the malignant teratoma. Lac:Cho ratio was 0.66 +/- 0.40, 0.58 +/- 0.30, and 0.08 +/- 0.12 for astrocytoma, ependymoma, and primitive neuroectodermal tumor, respectively. Lactate was elevated in the mixed glioma ependymo-astrocytoma, ganglioglioma, and teratoma. The NAA and lactate signals were sometimes obscured by lipids in the spectra. Discriminant analysis was carried out using NAA:Cho and Cr:Cho ratios to differentiate the three major tumor types. The sensitivity/specificity values for diagnosing astrocytoma, ependymoma, and primitive neuroectodermal tumor were found to be 0.91/0.84, 0.75/0.92, and 0.82/0.89, respectively, based on this study.CONCLUSIONIn many cases, proton MR spectroscopy can be used to help differentiate cerebellar primitive neuroectodermal tumor, low-grade astrocytoma, and ependymoma.     

Proton MR spectroscopy of the brain in infants

Proton magnetic resonance spectroscopy (MRS) was used to study the brain of 2 normal and 15 abnormal infants aged from 33 weeks postmenstrual age (PMA) to 14 months postnatal age. Eleven of the infants were examined on at least two occasions. The principal clinical diagnoses in the abnormal infants were perinatal ischemic and hemorrhagic brain injury. All proton spectra demonstrated peaks that were assigned to N-acetylaspartate (NAA), choline containing compounds (Cho), and creatine plus phosphocreatine (Cr). The NAA/Cho and NAA/Cr ratios increased with age, while the Cho/Cr ratio decreased with age in the majority of infants. The NAA/Cho ratio was generally lower in abnormal infants, but the difference was not apparent before 40 weeks (PMA). This ratio was lowest in infants with the severest degree of neurological abnormality. Proton and phosphorus MRS was compared in seven infants. In those with severe brain lesions, early phosphorus spectra were abnormal. On follow-up the phosphorus spectra became normal, but the proton spectra showed persistently low NAA/Cho and NAA/Cr ratios. Proton MRS provides new information that may be complementary to phosphorus MRS in the diagnosis and monitoring of brain development in normal and neurologically damaged infants.     

Proton MR spectroscopy in a 1T open MR imaging system

(1)H-MR spectroscopy is an established noninvasive MR imaging technique that can be helpful in the diagnosis of brain lesions and in treatment planning. Claustrophobia and body habitus preclude some patients from routine MR imaging in a closed-bore system. The development of (1)H-MR spectroscopy for use in an open MR imaging system would enable a more complete characterization of brain lesions in these patients.     

Proton MR spectroscopy in metabolic assessment of musculoskeletal lesions

OBJECTIVE: The purposes of this review are to describe the principles and method of MR spectroscopy, summarize current published data on musculoskeletal lesions, and report additional cases that have been analyzed with recently developed quantitative methods. CONCLUSION: Proton MR spectroscopy can be used to identify key tissue metabolites and may serve as a useful adjunct to radiographic evaluation of musculoskeletal lesions. A pooled analysis of 122 musculoskeletal tumors revealed that a discrete choline peak has a sensitivity of 88% and specificity of 68% in the detection of malignancy. Modest improvements in diagnostic accuracy in 22 of 122 cases when absolute choline quantification was used encourage the pursuit of development of choline quantification methods.     

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.