MR spectroscopic findings in a case of Alpers-Huttenlocher syndrome

Alpers-Huttenlocher syndrome, considered a mitochondrial disease, combines encephalopathy and liver failure. An 11-year-old boy with Alpers-Huttenlocher syndrome underwent conventional MR imaging, diffusion-weighted imaging, and proton MR spectroscopy. Diffusion-weighted imaging showed cytotoxic edema interpreted as acute-phase encephalopathy. MR spectroscopy revealed a lactate peak in the cortex that appeared abnormal on diffusion-weighted images, possibly representing respiratory deficiency with anaerobic metabolism. MR spectroscopy proved to be more sensitive regarding lactate detection than did neurometabolic examination of serum and CSF. A reduced N-acetylaspartate-creatine ratio was detected in both the cortex that appeared abnormal and the cortex that appeared normal on the diffusion-weighted images, indicating neuronal damage that was widespread, even beyond the boundaries of conventional MR imaging changes.     

Diffusion-weighted MR imaging findings of acute necrotizing encephalopathy

Multiple, symmetrical brain lesions affecting the bilateral thalami and cerebral white matter, which often show a concentric structure on CT and MR images, characterize acute necrotizing encephalopathy (ANE) of childhood. We describe the imaging findings of a 2-year-old child with ANE obtained with diffusion-weighted MR imaging. We discuss the significance of these findings, as well as the pathophysiology of ANE lesions, with reference to the appearance of the disease as revealed by diffusion-weighted MR imaging.     

Acute Necrotizing Encephalopathy: Diffusion MR Imaging and Localized Proton MR Spectroscopic Findings in Two Infants

In this report, we describe the findings of diffusion MR imaging and proton MR spectroscopy in two infants with acute necrotizing encephalopathy in which there was characteristic symmetrical involvement of the thalami. Diffusion MR images of the lesions showed that the observed apparent diffusion coefficient (ADC) decrease was more prominent in the first patient, who had more severe brain damage and a poorer clinical outcome, than in the second. Proton MR spectroscopy detected an increase in the glutamate/glutamine complex and mobile lipids in the first case but only a small increase of lactate in the second. Diffusion MR imaging and proton MR spectroscopy may provide useful information not only for diagnosis but also for estimating the severity and clinical outcome of acute necrotizing encephalopathy.     

Diffusion-weighted MR imaging and MR spectroscopy in glutaric aciduria type 1

Although conventional magnetic resonance imaging (MRI) findings of glutaric aciduria type 1 (GA-1) have been well established, diffusion weighted MR imaging (DWI) and proton MR spectroscopy (MRS) findings are limited. We report widespread restricted diffusion in the white matter and increased diffusion in bilateral putamen in a case of GA-1. The MRS showed decreased N-acetyl-aspartate (NAA)/creatine (Cr) ratio compared with a sex and age-matched control with no significant change in choline (Cho)/Cr ratio. The presence of the lactate peak reflecting disturbed mitochondrial functions in this disease has never been reported.     

Diffusion MR findings in cyclosporin-A induced encephalopathy

Cyclosporin encephalopathy is a well-known entity, which is clinically characterized by altered mental status, vision problems, focal neurological deficits and seizures. The exact pathophysiology of the cyclosporin encephalopathy has not yet been defined. We report the diffusion-weighted MR imaging and proton MR spectroscopy findings in a case of cyclosporin encephalopathy. The white-matter lesions with reversible restricted diffusion supported the hypothesis of reversible vasospasm induced by the cyclosporin.     

Magnetic resonance imaging and spectroscopy in a patient with treated methylmalonic acidemia

Magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (proton MRS) findings before and after carnitine therapy in a patient with methylmalonic acidemia (MMA) are evaluated. The hyperintensity on T2-weighted image and diffusion-weighted image and the decreased apparent diffusion coefficient of bilateral basal ganglia were normalized in parallel with normalization of the elevated lactate levels and the decreased N-acetyl-aspartate levels, corresponding to improvement of clinical symptoms. MRI and proton MRS may serve as a suitable, noninvasive modality for monitoring treated MMA.     

Multi-slice proton MR spectroscopy and diffusion-weighted imaging in methylmalonic acidemia: report of two cases and review of the literature

SUMMARY: Methylmalonic acidemia is an inborn disorder of amino acid metabolism that commonly presents with neurologic deficits. We present the results of multi-slice proton MR spectroscopy and diffusion-weighted imaging of the brain in two patients with methylmalonic acidemia. The findings consisted of restricted diffusion and elevated lactate in the globi pallidi, compatible with acute infarction (patient 1) and elevated lactate in CSF (patient 2).     

Comparison of conventional and diffusion-weighted MRI and proton MR spectroscopy in patients with mitochondrial encephalomyopathy,lactic acidosis,and stroke-like events

The mechanism of neurological disturbances in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is controversial. We studied 12 patients with MELAS using conventional and diffusion weighted MRI (DWI) and MR spectroscopy (MRS), to look at the physiopathology of the stroke-like events. Although conventional MRI showed lesions in all patients, DWI was more sensitive. One patient did not show high signal on DWI 48 h after a from stroke-like episode, but MRS demonstrated a lactate peak in left occipital lobe; 2 weeks after the attack, high signal was demonstrated on the right frontal lobe where MRS had shown a lactate peak. Our findings suggest a possible predictive ability of ¹H-MRS, in showing early MELAS lesions and supports the hypothesis that mitochondrial metabolic dysfunction may precedes abnormalities on DWI.     

线粒体脑肌病卒中样病灶的磁共振诊断及波谱分析

目的 探讨线粒体脑肌病伴高乳酸血症与卒中样发作事件(MELAS)脑内卒中样病灶的磁共振成像表现及~1H磁共振波谱特征.方法 回顾分析7例MELAS患者的临床及磁共振检查资料.结果 本组病例所行12次磁共振检查共计评价超急性期卒中样病变12个、急性期病灶12个、亚急性10个和慢性病灶6个.MELAS脑内卒中样病灶最初表现为局限大脑皮层的水肿信号灶,可累及皮层下区,多发于颞、枕、顶叶.磁共振扩散加权成像,病变在超急性期(3 d内)表现为以细胞毒性水肿为主,呈边界清楚的高信号灶;急性期(4～7 d)、亚急性期(2～4周)至慢性期(＞4周)病变逐步扩大,边界变模糊,以血管源性水肿为主.~1H磁共振波谱分析,脑卒中样病变在早期以高耸的双乳酸峰为特点,伴N-乙酰天门冬氨酸(NAA)等脑代谢物成分不同程度降低;随后,乳酸峰逐步降低,NAA等代谢物浓度可部分恢复.结论 MELAS卒中样病灶主要累及大脑皮层和皮层下区,细胞毒性水肿出现早但持续时间短,~1H磁共振波谱以典型的双乳酸峰为特征并伴有NAA浓度降低.     

Diffusion-weighted echo-planar MR imaging of CNS involvement in systemic lupus erythematosus

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the range of findings at diffusion-weighted magnetic resonance (MR) imaging in patients with systemic lupus erythematosus (SLE) and central nervous system involvement. MATERIALS AND METHODS: Diffusion-weighted MR images were reviewed in 20 patients with SLE and correlated with clinical symptoms and findings at computed tomography, conventional MR imaging, MR angiography, or conventional angiography. RESULTS: Diffusion-weighted MR imaging showed acute or subacute lesions in nine of 20 patients (45%). In the other 11, it showed no abnormal findings or chronic lesions. In four of the nine patients with lesions, diffusion-weighted imaging primarily showed hyperintense lesions with decreased apparent diffusion coefficient (ADC), which indicates acute or subacute infarcts. In four other patients, it primarily showed iso- or slightly hyperintense lesions with increased ADC, suggesting vasogenic edema. In two of these four patients, the findings were consistent with hypertensive encephalopathy. In the other two, small hyperintense foci on diffusion-weighted images with decreased ADC were seen within the vasogenic edema. These foci presumably represent microinfarcts associated with SLE vasculopathy. In the ninth patient, diffusion-weighted imaging showed a small linear hyperintense lesion with normal ADC in the left parietooccipital region. CONCLUSION: Diffusion-weighted imaging shows primarily two patterns of acute or subacute parenchymal lesions in patients with SLE: acute or subacute infarction and vasogenic edema with or without microinfarcts.     

Mitochondrial encephalomyopathy: comparison of conventional MR imaging with diffusion-weighted and diffusion tensor imaging: case report

Summary: Conventional MR imaging, MR spectroscopy, diffusion-weighted imaging, and diffusion tensor imaging were performed in a 5-month-old male patient with mitochondrial encephalomyopathy. On conventional T2-weighted MR images, symmetric, confluent high signal intensity was found in the temporoparietal white matter. A large lactate peak and decreased N-acetylaspartate were found in this region on proton MR spectroscopic images. Diffusion-weighted imaging showed increased apparent diffusion coefficient, representing vasogenic edema. Diffusion tensor imaging revealed decreased anisotropy, consistent with injury to the oligodendro-axonal unit. A muscle biopsy specimen revealed an isolated complex III enzyme respiratory chain deficiency. Diffusion-weighted and diffusion tensor imaging are valuable techniques for the characterization of hyperintense lesions on T2-weighted MR images in cases of mitochondrial encephalomyopathy.     

Thiamine deficiency in infants: MR findings in the brain

BACKGROUND AND PURPOSE: Thiamine deficiency is extremely rare in infants in developed countries. To our knowledge, its MR findings in the brain have not been reported. The purpose of this study was to investigate the brain MR findings in infants with encephalopathy due to thiamine deficiency. METHODS: The study group included six infants aged 2-10 months with encephalopathy who had been fed with solely soy-based formula devoid of thiamine from birth. All underwent MR evaluation at admission and follow-up (total of 14 examinations). In one patient, MR spectroscopy (MRS) was performed. RESULTS: In five patients T2-weighted, fluid-attenuated inversion recovery, or proton-attenuated sequences showed bilateral and symmetric hyperintensity in the periaqueductal area, basal ganglia and thalami. Five had lesions in the mammillary bodies, and three, in the brain stem. In all six patients, the frontal region (cortex and white matter) was clearly involved. At presentation, MRS of the periaqueductal area showed a lactate doublet. On long-term follow-up, three of four patients had severe frontal damage; in two, this occurred as part of diffuse parenchymal loss, and in one, it was accompanied by atrophy of the basal ganglia and thalami. CONCLUSION: Thiamine deficiency in infants is characterized by involvement of the frontal lobes and basal ganglia, in addition to the lesions in the periaqueductal region, thalami, and the mammillary bodies described in adults. MRS demonstrates a characteristic lactate peak.     

MRI及MRS对大脑胶质瘤病的诊断及鉴别诊断价值

目的评价MRI及MRS在大脑胶质瘤病的诊断和鉴别诊断中的价值。方法回顾性分析经活检、手术病理证实的6例大脑胶质瘤病患者的MRI和MRS表现特征,并与病理切片进行对照;常规行SE序列平扫及增强、DWI序列成像,其中3例行MRS研究,二维多体素、点分辨法PRESS、TE 144 m s。结果所有病例均侵犯2个脑叶或以上,同时伴胼胝体侵犯6例、基底节和丘脑侵犯4例、脑干侵犯2例。病变区呈长T2、稍长T1异常信号,T2WI、FLAIR上均为高信号,无坏死、钙化,受累区脑组织肿胀,占位效应轻。2例增强扫描见小结节状强化,4例无明显强化。3例MRS表现均有不同程度NAA降低,NAA/Cr比值降低,Cho上升,Cho/Cr和Cho/NAA的比值上升。结论MRI结合MRS对大脑胶质瘤病的诊断及鉴别诊断具有较大价值,结合临床、MRI及MRS是能够作出明确诊断的。     

Acute encephalopathy associated with intravenous immunoglobulin therapy

Intravenous immunoglobulin therapy is useful against various immune system disorders and viral infections. It is generally safe, and serious adverse reactions are uncommon. We report a rare case of acute encephalopathy following intravenous immunoglobulin therapy for human herpes virus 6 infection in a child. MR imaging findings suggest that the dominant causative mechanism of acute encephalopathy is cytotoxic edema, and the findings indicate 2 primary mechanisms. Reversibility of the restriction of water diffusion (low apparent diffusion coefficient value) on diffusion-weighted MR imaging suggests intramyelinic edema in the myelin sheath, and an increase of glutamate and glutamine complex peak on MR spectroscopy suggests excitotoxic injury to the neurons and astrocytes.     

Magnetic resonance spectroscopy (MRS) in five patients with treated propionic acidemia

Propionic acidemia is an inherited disorder caused by a defect of propionyl CoA carboxylase. Untreated, propionic acidemia leads to metabolic decompensation and toxic encephalopathy. We report on the magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) findings in five children who were properly treated by protein restriction and carnitine supplementation, during a phase of clinically and metabolically stable conditions. The examinations were performed on a whole-body 1.5 T scanner. During the observation period, from 1992 to 1996 we employed long echo time single-voxel spectroscopy and chemical shift imaging in addition to a conventional MRI protocol. The two children with the longest delay before onset of therapy showed cerebral atrophy. MRS yielded elevated lactate peaks in four of the children. These results indicate that MRS can detect metabolic alterations in the brains of children with propionic acidemia during metabolically stable conditions. The presence of lactate could be caused by hampered aerobic oxidation within the citrate cycle due to intracellular elevated propionic metabolites.     

(31)phosphorous and single voxel proton MR spectroscopy and diffusion-weighted imaging in a case of star fruit poisoning

We herein describe the case of a patient with chronic renal failure complicated by star fruit poisoning. T2-weighted and diffusion-weighted MR imaging showed hyperintense lesions at the thalami and right temporo-occipital cortex. Single voxel proton MR spectroscopy revealed elevation of lactate and (31)phosphorous MR spectroscopy revealed elevation of inorganic phosphate and decrease of phosphocreatine and nucleoside triphosphates. The imaging and metabolic changes indicated energy deprivation, with subsequent cortical necrosis proved at autopsy.     

MRI of influenza encephalopathy in children: value of diffusion-weighted imaging

PURPOSE: Our purpose was to describe the MR findings of influenza encephalopathy and assess the value of diffusion-weighted imaging for its diagnosis. METHOD: We examined a total of five patients diagnosed as having influenza encephalopathy or encephalitis by MRI, including diffusion-weighted imaging. We analyzed the conventional images and compared them with diffusion-weighted images. RESULTS: Abnormally hyperintense lesions of varying extent and location were noted on T2-weighted and fluid-attenuated inversion recovery images in the cortex and adjacent white matter in every case. They showed no contrast enhancement. Diffusion-weighted imaging demonstrated the lesions as areas of restricted proton diffusion more clearly than conventional imaging. CONCLUSION: Influenza encephalopathy is depicted as areas of T2 elongation having a rather nonspecific distribution. Diffusion-weighted imaging can demonstrate the lesions sensitively and serve as a valuable adjunct to conventional MRI.     

Brain stem hypertensive encephalopathy evaluated by line scan diffusion-weighted imaging

Hypertensive encephalopathy rarely presents with predominant involvement of the brain stem and relative sparing of the supratentorial regions. We describe the MR imaging features in a patient with reversible brain stem hypertensive encephalopathy. Extensive hyperintensity was predominantly seen in brain stem regions on fluid-attenuated inversion-recovery and T2-weighted images. These lesions showed an increased apparent diffusion coefficient with the use of line scan diffusion-weighted imaging. The clinical findings and MR imaging abnormalities resolved with control of hypertension.     

MELAS syndrome: imaging and proton MR spectroscopic findings.

PURPOSETo evaluate imaging findings in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, strokes) syndrome for the presence and location of infarctions and the presence of lactate.METHODSEight patients were studied with MR (n = 8) and CT (n = 2). One patient underwent single-photon emission CT with technetium 99m hexamethyl-propyleneamine oxime and one patient had conventional catheter angiography. One fixed brain was studied with MR imaging. Five patients underwent single volume proton MR spectroscopy. Imaging studies were evaluated for atrophy, edema, and infarctions. Proton MR spectroscopy was visually analyzed for presence or absence of lactate.RESULTSOne patient showed a cerebral infarction, and later a second distant infarction developed. One patient showed a transient area of cortical edema. Two patients had small nonspecific periventricular white matter abnormalities and one patient had diffuse white matter hyperintensities. Two patients had nonspecific MR abnormalities (probably age-related changes), and two had normal MR findings. None had basal ganglia involvement. Proton MR spectroscopy showed presence of lactate in one case with transient cortical edema; in two cases with nonspecific (probably age-related) brain findings; and in two patients with normal MR findings.CONCLUSIONSPatients with MELAS have a variety of MR findings. The fact that proton MR spectroscopy showed lactate in all five cases studied, regardless of MR findings, indicates that proton MR spectroscopy may be more sensitive in the detection of MELAS-associated abnormalities than MR imaging.     

Brain abscess and necrotic brain tumor: discrimination with proton MR spectroscopy and diffusion-weighted imaging

BACKGROUND AND PURPOSE: Discriminating pyogenic brain abscesses from cystic or necrotic tumors is sometimes difficult with CT or MR imaging. We compared findings of proton MR spectroscopy ((1)H-MRS) with those of diffusion-weighted imaging to determine which technique was more effective for this differential diagnosis. METHODS: Fourteen patients (necrotic or cystic tumor [n = 7]; pyogenic abscess [n = 7]) who underwent 1.5-T (1)H-MRS and diffusion-weighted imaging and had findings of ring-shaped enhancement after contrast agent administration were enrolled in this study. Diffusion-weighted imaging was performed with a single-shot spin-echo echo-planar pulse sequence (b = 1000 s/mm(2)). The apparent diffusion coefficient and ratio were also measured. RESULTS: Spectra for two patients were unacceptable because of either poor shimming conditions or contamination from neighboring fat. Spectra in three of five patients with abscess had lactate, amino acids (including valine, alanine, and leucine), and acetate peaks; one of the three spectra had an additional peak of succinate. In one patient with abscess treated by antibiotics, only lactate and lipid peaks were detected. Spectra for four of seven patients with cystic or necrotic tumors showed only lactate peaks. Lactate and lipids were found in three patients with tumors. Hyperintensity was seen in all the pyogenic abscess cavities and hypointensity in all the cystic and necrotic tumors on diffusion-weighted images. CONCLUSION: (1)H-MRS and diffusion-weighted imaging are useful for differentiating brain abscess from brain tumor, but the latter requires less time and is more accurate than is (1)H-MRS. (1)H-MRS is probably more limited in cases of smaller peripheral lesions, skull base lesions, and treated abscesses.