Maple syrup urine disease: findings on CT and MR scans of the brain in 10 infants

Ten infants with classical maple syrup urine disease (MSUD) and two with variant MSUD had a total of 26 CT scans and 13 MR examinations of the brain during different stages of their disease. We found that inter- and intrapatient analyses of CT and MR findings at times ranging from 3 days to 7 months were typical enough to suggest the MSUD diagnosis. Imaging studies showed the natural course of the disease and, in a few cases, illustrated the effects of therapy. CT scans typically are negative during the first few days of life, then a marked, generalized, diffuse edema appears. In addition, a localized, more severe edema (the MSUD edema) is seen, which involves the deep cerebellar white matter, the dorsal part of the brainstem, the cerebral peduncles, and the dorsal limb of the internal capsule. Both the generalized and the MSUD edema subside during the second month of life, then may disappear totally or leave a well-defined, low-density zone around the lateral ventricles and small, low-attenuation lesions within the brainstem, respectively. With the disappearance of the edema, some loss of brain substance becomes obvious.     

MR diffusion imaging and MR spectroscopy of maple syrup urine disease during acute metabolic decompensation

Maple syrup urine disease (MSUD) is an inborn error of amino acid metabolism, which affects the brain tissue resulting in impairment or death if untreated. Imaging studies have shown reversible brain edema during acute metabolic decompensation. The purpose of this paper is to describe the diffusion-weighted imaging (DWI) and spectroscopy findings during metabolic decompensation and to assess the value of these findings in the prediction of patient outcome. Six patients with the diagnosis of MSUD underwent conventional MR imaging with DWI during acute presentation with metabolic decompensation. Spectroscopy with long TE was performed in four of the six patients. Follow-up examinations were performed after clinical and metabolic recovery. DWI demonstrated marked restriction of proton diffusion compatible with cytotoxic or intramyelinic sheath edema in the brainstem, basal ganglia, thalami, cerebellar and periventricular white matter and the cerebral cortex. This was accompanied by the presence of an abnormal branched-chain amino acids (BCAA) and branched-chain alpha-keto acids (BCKA) peak at 0.9 ppm as well as elevated lactate on proton spectroscopy in all four patients. The changes in all six patients were reversed with treatment without evidence of volume loss or persistent tissue damage. The presence of cytotoxic or intramyelinic edema as evidenced by restricted water diffusion on DWI, with the presence of lactate on spectroscopy, could imply imminent cell death. However, in the context of metabolic decompensation in MSUD, it appears that changes in cell osmolarity and metabolism can reverse completely after metabolic correction.     

Cerebral computed tomography in maple syrup urine disease

Maple syrup urine disease (MSUD) is an inherited metabolic disorder due to decreased decarboxylation of branched chain keto acids triggering an accumulation of leucine, isoleucine, and valine. We describe two infants with biochemically confirmed MSUD in whom computed tomography (CT) revealed cerebral edema. In one of these cases repeat CT 40 days after institution of appropriate therapy revealed that the edema had disappeared and the ventricles had enlarged.     

Computed tomography in Pelizaeus-Merzbacher disease

Summary CT findings in two related males suffering from the classical X-linked recessive form of Pelizaeus-Merzbacher disease (PMD) are described. CT revealed marked cerebellar atrophy and focal areas of demyelination of cerebral white matter in a 25-year-old patient. This agrees with known neuropathological changes. However, CT was normal in the 14-year-old nephew, although his neurological symptoms were nearly as severe as his uncle's. Judging from this observation and from the scant information in the literature it seems that CT in classical PMD is normal in the first decade and is therefore not helpful in confirming the diagnosis of PMD at an early stage.     

Maple syrup urine disease: diffusion-weighted MRI findings during acute metabolic encephalopathic crisis

Maple syrup urine disease (MSUD) is caused by a genetic defect of branched-chain amino acids, which include leucine, isoleucine and valine. We report diffusion-weighted imaging (DWI) findings in a newborn child with MSUD who presented with acute metabolic encephalopathic crisis. DWI (b = 1,000 s/mm(2)) showed high signal localized within the myelinated white matter (WM) areas including the cerebellar white matter, pons, bulbus, cerebral peduncles, lentiform nucleus, posterior limbs of the internal capsules, corona radiata and bilateral perirolandic cortex. The apparent diffusion coefficient values of these regions were markedly low in the affected areas. The presence of these findings was considered cytotoxic or intramyelinic edema evidenced by restricted water diffusion. In conclusion, our findings suggest that during the acute phase and early encephalopathic crisis stage of MSUD, DWI can demonstrate the involvement of myelinated WM in newborns.     

Maple syrup urine disease: diffusion-weighted and diffusion-tensor magnetic resonance imaging findings

We present conventional magnetic resonance (MR) imaging with diffusion-weighted and diffusion-tensor imaging findings in a 10-day-old neonate with maple syrup urine disease (MSUD). On conventional MR imaging, signal abnormalities were noted in the affected white matter of cerebellum, dorsal brainstem, thalami, posterior limbs of internal capsules, and the corona radiata. These regions showed marked hyperintensity on diffusion-weighted images with decreased apparent diffusion coefficient values (average 68% reduction). Diffusion-tensor imaging showed decreased anisotropy (average 57% reduction) in the corresponding areas. Both diffusion-weighted and diffusion-tensor imaging are valuable in the diagnosis and understanding of the pathogenesis of MSUD, with findings that suggest cytotoxic edema and damaged oligodendro-axonal units within the affected white matter.     

Computed tomography studies on patients with mucopolysaccharidoses

Summary The appearances on computed tomography (CT) in eight patients with mucopolysaccharidosis Type I [five with classical Type IH (Hurler disease)], two with mucopolysaccharidosis Type II (Hunter disease) and two with mucopolysaccharidosis Type IIIB (Sanfilippo B disease) are presented. Reference is also made to two further cases [mucopolysaccharidosis VI and mucopolysacharidosis IIIB] in which the CT showed special features. Follow-up scans were obtained to assess the evolution of the changes. The interplay of neuronal damage, cerebral atrophy and obstruction to the cerebrospinal fluid (CSF) circulation in the production of the cerebral manifestations, and the extent to which non-genetic factors influence the expression of the underlying biochemical lesion, are discussed. This series of patients illustrates the problem of classifying those with -iduronidase deficiency, who do not have the classical Hurler disease phenotype (mucopolysaccharidosis IS and IH/S; Scheie disease and Hurler/Scheie disease), on the basis of currently available criteria. The place of CT in the diagnosis of complications due to thecal involvement is examined. The density of grey matter on the CT scans was similar to that of normal brain. Inhaled xenon did not produce any special enhancement which could be helpful in assessing the degree of the mucopolysaccharide deposition within cerebral cells. Symmetrical low attenuation in the white matter was a very common finding. It was not specifically associated with hydrocephalus and its relationship to some of the known neuropathological aspects of mucopolysaccharidoses is discussed. This work has shown that the stage in the evolution of the mucopolysaccharidoses at which hydrocephalus develops as a complication is highly variable and CSF diversion procedures are sometimes indicated to improve the quality of the patients' lives. These indications are briefly discussed. We consider that CT is essential for the adequate appraisal of these patients and to identify some treatable complications.     

Computed tomography in neuronal ceroid lipofuscinosis

Summary The computed tomography (CT) findings in a verified case of neuronal ceroid lipofuscinosis (NCL) are presented. CT revealed diffuse and severe cerebral atrophy, reflected by generalized subarachnoid space enlargement and symmetric ventricular dilation. There was no evidence of abnormalities of the white matter. The CT features in our case of NCL correspond perfectly with the neuropathologic changes of the disease mentioned in the literature. Furthermore, CT is of considerable help in differentiating between those inherited metabolic brain diseases characterized primarily by white matter involvement and those presenting predominantly with changes of grey matter.     

X-ray computed tomography and MRI in Krabbe's disease

Krabbe's disease whose CT appearance is well known should benefit of the development of MRI as this method is more accurate. MRI permits early diagnosis of leucodystrophy. Yet it must be emphasized that abnormal white matter patterns are not sufficient to permit the diagnosis of Krabbe disease. In the case reported atrophy of the brain, the cerebellum and the brain-stem, demyelination of the white matter and necrosis of corpus callosum were observed. The abnormalities of the brain on MRI pictures help in the diagnosis as they may alert clinicians to the possibility of Krabbe disease in infants with progressive encephalopathy. A definitive diagnosis can be established thanks to the laboratory tests.     

海洛因白质脑病的CT与MRI诊断

目的 研究CT与MRI对烫吸海洛因蒸汽引起海绵状白质脑病的特征性影像学诊断价值。方法 对2例烫吸海洛因引起的海绵状白质脑病的患者进行了临床和CT与MRI观察，查阅中外文献，对该病影像学特征结合临床表现、病理组织改变进行总结与讨论。结果 2例患者以小脑性共济失调、智力减退为主要临床表现，CT显示对称性分布的小脑白质、大脑白质为主的低密度改变；MRI显示对称性分布的小脑齿状核，大脑半球半卵圆中心、双基底节内囊、中脑、桥脑白质纤维为主的高信号改变。结论 烫吸海洛因引起海绵状白质脑病的CT与MRI影像学改变具有特征性，能为临床诊断提供可靠依据，从而使本病能够得到早期确诊。     

Diffusion-weighted MRI of maple syrup urine disease encephalopathy

We report the case of a newborn child with maple syrup urine disease (MSUD), diagnosed at 10 days of life. Diffusion-weighted echoplanar MRI showed marked hyperintensity of the cerebellar white matter, the brainstem, the cerebral peduncles, the thalami, the dorsal limb of the internal capsule and the centrum semiovale, while conventional dual-echo sequence evidenced only a weak diffuse T2 hyperintensity in the cerebellar white matter and in the dorsal brainstem. The apparent diffusion coefficient (ADC) of these regions was markedly (>80%) decreased. Therefore, in agreement with current hypotheses on MSUD pathogenesis, MSUD oedema proves to be a cytotoxic oedema. Diffusion-weighted MRI may be a valuable tool, more sensitive than conventional spin-echo techniques, to assess the extent and progression of cytotoxicity in MSUD, as well as the effectiveness of the therapeutic interventions.     

18F-FDG PET/CT in the diagnosis of Takayasu arteritis: A case report

The early clinical symptoms of Takayasu arteritis (TAK) are nonspecific and often lead to misdiagnosis or delay in diagnosis. And by the time morphological changes are observed on the images, the disease is in an advanced stage and irreversible vascular injuries has occurred. Therefore, early correct diagnosis and timely systemic anti-inflammatory treatment can effectively improve the clinical situation. Conventional imaging provides only changes in vascular structure and provides little information on inflammatory activity. Here we report the PET/CT imaging presentation of 18F-deoxyglucose (¹⁸F-FDG) in a patient with TAK, a 58-year-old patient with known TAK whose disease clustered many non-specific features, and highlight the value of PET/CT in the diagnosis and management of patients with early or atypical clinical presentation of TAK.Keyword: TAK, PET/CT, Diagnosis     

Malignant hyperphenylalaninemia: CT and MR of the brain

A defect in biopterin synthesis not only prevents the transformation of phenylalanine to tyrosine (as in classical phenylketonuria, PKU) but also blocks the biosynthesis of the neurotransmitters dopamine, norepinephrine, and serotonin, causing severe neurologic disturbances. The brain CT and MR findings in this rare disorder have not been described. In the present series, eight patients with PKU were all examined with CT, three were also examined with MR imaging. In spite of severe clinical findings, CT was normal or almost normal in three patients; in three other children, moderate loss of brain volume was found. White matter disease was found in three patients (moderate in two and severe in one) and was also found in an additional patient with classical PKU. PKU should therefore be added to the list of possible causes for white matter disease. Furthermore, biopterin-dependent PKU should be considered when the CT examination in a child with severe neurologic manifestation only shows discrete pathology.     

PET, CT, and MRI in the evaluation of neuropsychiatric disorders: current applications

Positron emission tomography (PET) is emerging as a very useful clinical tool and is adding a great deal to our understanding of the pathophysiology of central nervous system (CNS) disorders. Although computed tomography (CT) and magnetic resonance imaging (MRI) have had a dramatic impact on patient management, there is often an important associated function abnormality which is best assessed by PET. In normal aging and in dementia, the CT and MRI brain changes of atrophy and white matter abnormalities are frequently nonspecific. PET has been more diagnostic, showing characteristic regional metabolic abnormalities. Evaluation of brain tumors such as astrocytomas with PET has demonstrated better correlation with histologic grade compared to CT. Unlike CT or MRI, PET can help to distinguish radiation necrosis from recurrent tumor, and can differentiate the extent of metabolically active tumor from surrounding edema. PET is useful in evaluating stroke patients, providing better prognostic information and demonstrating abnormalities sooner than CT. In epilepsy, PET appears to be superior to MRI in localizing seizure foci in patients with partial seizures. In head trauma patients, metabolic patterns are being described which will likely have an effect on patient management. The use of PET in schizophrenia has yielded very interesting results, with common patterns of metabolic abnormalities being demonstrated. CT and MRI in these patients have not been very useful. PET has also shown promise in movement disorders such as Huntington's disease. It is now clear that PET is already clinically useful and can provide valuable information unobtainable by CT and MRI. As new radioligands are developed, PET is certain to assume an even more important role in the future.     

Regional correlation of PET and CT in senile dementia of the Alzheimer type

Alzheimer disease is manifested by both widespread and regionally restricted brain changes, some of which have recently been identified in vivo with computed tomography (CT) and positron emission tomography (PET). This is a report of the regional correlation of CT and PET measurements in 19 carefully diagnosed subjects comprising 11 controls and eight patients with senile dementia of the Alzheimer type. Regional CT attenuation values did not discriminate between the two groups, but PET using 18F-2-deoxy-2-fluoro-D-glucose demonstrated significant regional reductions (range, 21%-28%) in glucose utilization in the Alzheimer group. PET measures were also more consistently related to cognitive decline. The correlation between CT structural measures and PET metabolic measures demonstrated consistent relations between widespread PET regions and CT changes in the thalamus, posterior limb of the internal capsule, and temporal lobes. However, CT changes in the frontal white matter, caudate nucleus, and anterior limb of the internal capsule were not related to any regional PET changes. These data support previous findings of temporal lobe involvement in Alzheimer disease and suggest the involvement of structures in the region of the third ventricle.     

脑放射损伤的影像学研究进展

脑放射损伤发病机制主要有三种学说即血管损伤、胶质损伤和免疫反应机制,最近多数学者的研究支持血管和胶质损伤机制,血管方面的改变在晚期放射效应中起主要作用。CT和MRI对局限性脑损伤和弥漫性脑白质损伤可明确诊断。MRI的T₂加权成像(T₂WI)显示水分变化敏感性高,又不受颅底线束硬化伪影的影响,MRI发现白质病变的敏感性是CT的2~3倍。如果是脑本身肿瘤放疗后,CT和MRI区别病灶复发或放射性坏死比较困难,PET和MRS(磁共振波谱成像)在两者鉴别诊断中则初步呈现出一定的优势。行PET检查时,如为肿瘤则代谢活跃,坏死则代谢低下,但敏感性和特异性欠理想。MRS测量感兴趣区内代谢产物的量或比率有助于两者的鉴别诊断。另外,PET功能成像和MRS还可预测放疗病人较早期无症状的可逆性放射损伤,以便及时应用激素等药物治疗,避免其进一步发展为临床症状明显的不可逆性损伤。     

Neonatal herpes simplex encephalitis: correlation of clinical and CT findings

Review of 31 computed tomographic (CT) scans in 15 neonates with herpes simplex encephalitis (HSE) type 2 revealed the most characteristic early findings to be patchy and widespread areas of low attenuation, primarily in white matter, with minimal contrast material enhancement in a meningeal pattern. The low-attenuation lesions increased rapidly in size and prominence during the course of the disease. This was usually accompanied by increased attenuation of cortical gray matter that persisted for weeks to months. Atrophic changes appeared rapidly, being evident in the 3d week. Late findings consisted of very extensive, diffuse, low attenuation of white matter with cortical atrophy. Calcification assumed a variety of distributions, from punctate to an extensive gyral pattern. The cerebellum was involved in nine patients. Early CT findings were not good predictors of outcome, but later serial CT scans showing progression or stability of findings were more accurate in prognosis. CT serves primarily to confirm the diagnosis of neonatal HSE.     

Age dependence of diffusion-weighted magnetic resonance imaging findings in maple syrup urine disease encephalopathy

A patient with maple syrup urine disease (MSUD) who developed encephalopathy twice and underwent magnetic resonance examinations, including diffusion-weighted (DW) imaging, is presented. Areas of abnormal intensity on DW images dramatically differed between the initial and second attacks, apparently attributable to the difference in myelination. Our observation demonstrates the age dependence of DW imaging findings in MSUD encephalopathy attributable to progression of myelination and would help in the proper diagnosis of MSUD encephalopathy at any age.     

18F-FDG PET/CT显像用于肺癌诊疗的研究进展

常规¹⁸F-FDG PET/CT静态显像在肺癌的诊断、分期、疗效评估等方面发挥了重要作用,并能通过标准化摄取值等代谢参数进行半定量分析,但静态显像无法提供病变的示踪动力学信息。近年出现的动态显像技术能够连续评估某一时间段内病变的代谢变化过程,并可应用净摄取速率常数等动力学参数进行定量分析,与静态显像相互补充,为肺癌的诊断提供更丰富的信息。就 ¹⁸F-FDG PET/CT静态及动态显像在肺癌诊疗中的研究进展进行综述。     

Relative efficacy of radionuclide imaging and computed tomography of the brain.

Computed tomography (CT) with the EMI scanner has been demonstrated to possess a wide spectrum of capabilities in the diagnosis of suspected intracranial disease. This review of 418 dual CT and radionuclide (RN) brain images indicates that RN and CT are complementary in the diagnosis of cerebral infarction, but that CT has a greater capability in brain tumor detection. The classical RN static brain image does not detect cerebral atrophy, hydrocephalus or intraventricular hemorrhage; these conditions are clearly defined by CT.