18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in propionic acidemia: clinical and MRI correlations.

The clinical data and the imaging findings of the positron emission tomography (PET) and the magnetic resonance imaging (MRI) studies in five patients, previously diagnosed to have propionic acidemia, were retrospectively reviewed. The patients were all normal at birth. The first clinical signs, typically hypotonia and failure to thrive, appeared during the first 2 years of life. With progression of the disease, the neurological findings consisted of variable degrees of dementia and extrapyramidal symptoms, notably dystonia, choreoathetosis and rigidity of variable degrees. Initial cerebral PET and MRI studies were normal. Follow-up MRI examinations showed progressive basal ganglia degeneration, with evidence of atrophy and signal abnormalities within the caudate nuclei and the putamina. The thalamic structures were normal. The PET studies demonstrated increased uptake in the basal ganglia and thalami, followed by decreased uptake in the basal ganglia at a later stage of the disease. The structural (MRI) and the functional (PET) studies of the brain were found to be complementary in the evaluation of propionic acidemia, and were in good correlation with the clinical findings.     

18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in glutaric aciduria type 1: clinical and MRI correlations

The clinical, PET (positron emission tomography) and MRI (magnetic resonance imaging) findings of brain studies in eight patients, previously diagnosed to have glutaric aciduria type 1, were retrospectively reviewed. The neurological findings typically consisted of variable degrees of dementia and extrapyramidal symptoms (dystonia, choreoathetosis and rigidity). Both MRI and PET showed involvement of the putamina in all the patients. The PET scan demonstrated lesions in the head of the caudate nuclei in all of the patients. Brain atrophy, and in particular the characteristically-enlarged Sylvian fissures, was better demonstrated by MRI. On the other hand, the cerebral cortex and thalamic structures were found to be normal by MRI in all patients, whereas PET scan showed decreased uptake in the cerebral cortex in seven, and in the thalami in three patients. Correlation between imaging and clinical findings was found to be good when both PET scan and MRI findings of the brain were taken into consideration. Therefore, the functional (PET) and structural (MRI) studies of the brain were complementary in the imaging evaluation of glutaric aciduria type 1.     

White matter lesions in Fabry disease occur in 'prior' selectively hypometabolic and hyperperfused brain regions

Fabry disease is an X-linked disorder associated with early onset stroke. We previously found a significantly elevated cerebral blood flow (CBF) in patients with Fabry disease. We set to determine whether elevated resting CBF in Fabry disease is primarily a cerebrovascular abnormality or is secondary to enhanced neuronal metabolism. The relationship of cerebral metabolism and blood flow to Fabry leukoencephalopathy was also investigated. We measured the global and regional cerebral metabolic rate of glucose using 18-fluoro-deoxyglucose (FDG) and PET in 16 patients with Fabry disease (7 patients with leukoaraiotic lesions and 9 without) and in 7 control subjects. MRI fluid attenuated inversion recovery (FLAIR) studies were also performed in the patient and control groups. All control subjects had normal MRI FLAIR studies with no high-signal deep white matter lesions (WML). Patients were partitioned into FLAIR lesion and non-FLAIR lesion groups. We found no evidence of cerebral glucose hypermetabolism in Fabry disease. On the contrary, significantly decreased regional cerebral glucose metabolism (rCMRGlu) was found particularly in the deep white matter in the Fabry non-lesion group and exacerbated in the lesion group. Lesion-susceptible regions were relatively hyperperfused in non-lesion patients compared to the control group. We conclude that the elevated rCBF and decreased white matter rCMRGlu indicates a dissociation between metabolism and blood flow suggesting chronic deep white matter metabolic insufficiency.     

Methyl-11C]thymidine positron emission tomography in tumoral and non-tumoral cerebral lesions.

BACKGROUND: No ideal radiopharmaceutical exists for positron emission tomography (PET) that fulfills all clinical requirements for the study of brain tumors. PURPOSE: The usefulness of a recently developed PET tracer, [methyl-11C]thymidine ([methyl-11C]TdR) is explored in brain tumors. PATIENTS AND METHODS: Twenty patients with confirmed tumoral and non-tumoral brain lesions were investigated with [methyl-11C] TdR PET. The 11C activity was visually and quantitatively assessed. In two patients, dynamic scans were performed. The PET findings were compared to those of magnetic resonance imaging (MRI) or computed tomography (CT) of the brain and to the final diagnosis. RESULTS: Eight out of ten patients with confirmed tumoral lesions or tumor recurrence had increased 11C activity within the lesion. In ten non-tumoral lesions no increased 11C uptake was found. The dynamic PET studies showed that [methyl-11C] TdR first acts as a blood flow tracer, but that later on the uptake of 11C activity is due to labeled metabolites, crossing the blood-brain barrier. Increased tracer activity was only observed in tumoral and not in non-tumoral contrast-enhanced lesions on MRI or CT. CONCLUSIONS: [Methyl-11C] TdR is not a selective PET radiopharmaceutical for brain tumors, but can be used as a tracer for tumoral blood-brain barrier disruption.     

Positron emission tomography (PET) in "pure akinesia".

Positron emission tomography (PET) studies on regional cerebral glucose metabolism and [18F]fluorodopa uptake were performed on 3 patients with "pure akinesia without rigidity and tremors", 3 progressive supranuclear palsy (PSP) patients, and 5 patients with Parkinson's disease. The "pure akinesia" and PSP patients showed a marked decrease in glucose metabolism in the frontal cortex and striatum, and a decreased uptake of [18F]fluorodopa in the striatum. While the Parkinson's disease patients had a decreased uptake of [18F]fluorodopa in the striatum but no abnormality in the glucose metabolism. Magnetic resonance imaging (MRI) showed atrophy of the pretectum and dorsal pons in "pure akinesia" and PSP patients, but there was no such abnormality in the Parkinson's disease patients. As described above, patients with "pure akinesia" and PSP patients revealed similar findings on PET and MRI studies, while Parkinson's disease patients showed substantially different results.     

阿尔茨海默病~(18)F-FDG PET显像诊断的研究

目的 探讨阿尔茨海默病（AD）脑葡萄糖代谢及其18F-脱氧葡萄糖正电子发射计算机断层扫描（18F-FDG PET）显像的影像学特征和PET诊断标准。方法 静脉注射18F-FDG后行脑断层显像,检查13例 AD、13例非AD痴呆及13例正常人。获得纹状体、丘脑、黑质、顶叶、颞叶、额叶、枕叶、海马单位面积放射性计数与小脑计数的比值（Rcl/cb）,进行半定量分析,并与MR进行对照。结果AD患者PET异常率为100％,MR异常者占10/13。PET显像特征:①对称性双侧颞顶叶及海马伴额叶或枕叶代谢减低占9例（9/13）;②双侧颞叶对称性代谢减低伴海马或额叶代谢下降占3例（3/13）;③双顶叶对称性代谢降低1例（1/13）。12例（12/13）非AD痴呆表现为不对称、多发性代谢降低,降低区位于黑质、纹状体、丘脑及脑皮质区,MR异常率为11/13。结论 在除外脑内结构特异性损害基础上,PET发现对称性双颞顶叶、海马或颞叶、顶叶,伴或不伴枕叶、额叶代谢下降,可诊断AD。PET对AD早期诊断及鉴别诊断具有临床意义。     

基底节区生殖细胞肿瘤一例并文献复习

目的探讨基底节区生殖细胞肿瘤(basal ganglia germinoma,BGG)临床和影像学特点,以提高对早期BGG的认识。方法分析作者医院收治的1例BGG患者的临床资料及诊治、转归情况并复习相关文献。结果患者男性,17岁,病程28个月。发病时表现为智能减退、左侧肢体痉挛性瘫痪。发病7个月时头颅MRI未见明确占位征象;发病28个月时头颅MRI发现右侧基底节区巨大囊实性占位病变,左侧基底节区小病灶。双侧基底节区MRS分析发现,右侧胆碱(Cho)峰显著升高,肌酐(Cr)和N-乙酰天冬氨酸(NAA)峰明显降低,Cho/Cr增加;左侧Cho峰明显升高,Cr和NAA峰无明显变化,Cho/Cr>1。血人绒毛膜促性腺激素(β-HCG)和甲胎蛋白(AFP)水平明显增高,分别为3481.4mIU/mL和32.1ng/mL。临床诊断为生殖细胞肿瘤,行开颅手术将右侧病变大部切除。病理证实为混合性生殖细胞肿瘤。结论 (1)患者可能有双侧BGG;(2)BGG早期诊断困难,根据临床和MRI表现,动态观察血和脑脊液中β-HCG和AFP的变化,必要时行进一步的影像学检查(MRS或11 C-蛋氨酸PET/CT)及病灶活检,以提高早期诊断率。     

18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in type IV 3-methylglutaconic aciduria: clinical and MRI correlations

The clinical, 18fluorodeoxyglucose positron emission tomography (18FDG PET) and the magnetic resonance imaging (MRI) brain scan characteristics of four patients diagnosed to have 3-methylglutaconic aciduria were reviewed retrospectively. The disease has a characteristic clinical pattern. The initial presentations were developmental delay, hypotonia, and severe failure to thrive. Later, progressive encephalopathy with rigidity and quadriparesis were observed, followed by severe dystonia and choreoathetosis. Finally, the patients became severely demented and bedridden. The 18FDG PET scans showed progressive disease, explaining the neurological status. It could be classified into three stages. Stage I: absent 18FDG uptake in the heads of the caudate, mild decreased thalamic and cerebellar metabolism. Stage II: absent uptake in the anterior half and posterior quarter of the putamina, mild-moderate decreased uptake in the cerebral cortex more prominently in the parieto-temporal lobes. Progressive decreased thalamic and cerebellar uptake. Stage III: absent uptake in the putamina and severe decreased cortical uptake consistent with brain atrophy and further decrease uptake in the cerebellum. The presence of both structural and functional changes in the brain, demonstrated by the combined use of MRI and 18FDG PET scan, with good clinical correlation, make the two techniques complementary in the imaging evaluation of 3-methylglutaconic aciduria.     

A case of herpes simplex encephalitis with noticeable findings of SPECT]

A 51-year-old man was admitted to our hospital because of fever, general fatigue and disturbance of consciousness. Neurological findings included disturbed consciousness, stiff neck and positive Kernig's sign. He was diagnosed as having herpes simplex encephalitis with HSV-DNA in the cerebrospinal fluid. MRI showed a lesion with low signal intensity in T1-weighted image and high signal intensity in T2-weighted image in the right temporal lobe. The single photon emission CT (SPECT) study showed discordance of 99mTc ethyl cysteinate dimer-SPECT (ECD-SPECT) and N-isopropyl-p-[123I]-iodoamphetamine-SPECT (IMP-SPECT). Decreased signal of ECD in the lesion where IMP uptake was increased could be due to decreased esterase activity. This report suggests that ECD-SPECT could fail to detect cerebral blood flow in the lesion with severe metabolic damage.     

Whipple''s disease and the central nervous system a case report and a review of the literature

A 65-year-old man was suffering from recurrent manic psychosis accompanied by weight loss. He also had a history of pleural effusion, aspecific migratory non-deforming seronegative polyarthritis, sensorineural hearing loss and semicircular canal paresis. Whipple's disease (WD) had been diagnosed at the age of 63 years. On admission to hospital)he had weight loss, diarrhoea in combination with an organic, brain syndrome, hemiparesis and ophthalmoplegia, including internuclear ophthalmoplegia (INO). A clinical diagnosis of central nervous system (CNS) WD was made. MRI revealed a thalamus lesion that halved in size during sulfamethoxazole-trimethop:rim treatment. The organic brain syndrome and ophthalmoplegia diminished also, as did the cerebrospinal fluid (CSF) IgG level. A review of CNS WD is presented and implications for treatment are discussed.     

Effect of partial volume correction on estimates of the influx and cerebral metabolism of 6-[(18)F]fluoro-L-dopa studied with PET in normal control and Parkinson's disease subjects

The poor spatial resolution of positron emission tomography (PET) is a limiting factor in the accurate assay of physiological processes investigated by compartmental modeling of tracer uptake and metabolism in living human brain. The radioactivity concentration in a region-of-interest is consequently altered by loss of signal from that structure and contamination from adjacent brain regions, phenomena known as partial volume effects. We now apply an MRI-based algorithm to compensate for partial volume effects in the special case of compartmental modeling of the cerebral uptake of 6-[(18)F]fluoro-L-dopa (FDOPA), an exogenous substrate of dopa decarboxylase. High-resolution MRI scans were obtained from normal volunteers (n = 4) and patients with Parkinson's disease (n = 4) in order to segment specific brain regions and calculate the partial volume correction factors. Dynamic 2D PET scans were acquired during 90 min following intravenous infusion of FDOPA. After partial volume correction, the apparent net blood-brain clearance of FDOPA (K(i)) was greatly increased in caudate and putamen of normal subjects and in caudate of Parkinson's disease patients. The equilibrium distribution volume of FDOPA (V(D)(e)) in cerebral cortex increased by 35% in all subjects. Using a two-compartment model, the relative activity of dopa decarboxylase with respect to FDOPA (k(D)(3)) in the basal ganglia was increased 2-3 times in normal subjects, to the range obtained previously in brain of living rat. The partial volume correction also increased the magnitude of k(D)(3) in caudate of Parkinson's disease patients, but did not alter k(D)(3) in putamen. A three-compartment model correcting for elimination of decarboxylated metabolites also yielded higher estimates of k(D)(3), but with a penalty in precision of the estimates. Together, these observations suggest that the limited spatial resolution of PET results in substantial underestimation of the true rate of FDOPA uptake and metabolism in vivo, and may also tend to obscure regional heterogeneity in the neurochemical pathology of Parkinson's disease.     

Whipple''s disease confined to the CNS presenting with multiple intracerebral mass lesions.

A patient with isolated cerebral Whipple's disease presented with signs of raised intracranial pressure and multiple ring enhancing intracerebral mass lesions evident on CT and MRI imaging. Characteristic intracellular bacilliform inclusions were identified in a brain biopsy. Clinical improvement followed treatment with parenteral antibiotics for two weeks and long term sulphamethoxazole-trimethoprim. As CNS relapse of Whipple's disease may occur after several years, long term treatment should include antibiotics that are able to cross the blood-brain barrier.     

Comparison of PET, MRI, and CT with pathology in a proven case of Alzheimer's disease

Positron emission tomography (PET) with fluorodeoxyglucose (FDG), magnetic resonance imaging (MRI), and CT were carried out in a patient with Alzheimer's disease 16 months before he died. At autopsy, the gross appearance of the brain correlated with MRI and CT, which showed some regional atrophy. These were much less revealing than PET, which correlated with microscopic findings of neuronal loss and proliferation of glia. In areas of moderately impaired local cerebral metabolic rate of glucose, as revealed by reduced FDG uptake, there was some gliosis, primarily around the numerous senile plaques. In areas of severe metabolic impairment, there was a profound loss of neurons, extensive gliosis, and a diminished appearance of plaques. PET-FDG is a better measure of the severity of Alzheimer's disease than MRI or CT, because it reflects the degree of neuronal pathology.     

Cerebral Whipple's disease with a stroke-like presentation and cerebrovascular pathology

Although neurological symptoms are common in Whipple's disease, patients rarely have a purely neurological presentation and involvement restricted to the central nervous system is uncommon. A 39 year old woman presented with a meningoencephalitic illness, which responded to penicillin. Eleven months later she developed recurrent stroke-like episodes. Patchy enhancing meningeal, cortical, and subcortical lesions thought to be vascular in origin developed within nine days of the onset of symptoms. No evidence was found of a cardiovascular source of emboli, vasculitis, or thrombophilic condition. A brain biopsy showed meningoencephalitic features suspicious of Whipple's disease associated with leptomeningeal arterial fibrosis and thrombosis. DNA polymerase chain reaction confirmed Tropheryma whippelii in both blood and brain tissue. The neurological manifestations of cerebral Whipple's disease are varied and very rarely include stroke-like symptoms. The pathogenesis of cerebral infarction in Whipple's disease is not well established but arterial fibrosis and endocarditis complicated by embolisation have been reported. This case emphasises the importance of early brain biopsy in unusual cases of stroke and illustrates the clinical utility of polymerase chain reaction to confirm Whipple's disease.     

Indications for Differential Diagnosis of Nontumor Central Nervous System Diseases from Tumors

To accurately differentiate nontumor central nervous system (CNS) diseases from brain tumors, we retrospectively evaluated the cerebral circulation and metabolism in patients with nontumor CNS diseases using positron emission tomography (PET). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), the metabolic rates of oxygen (rCMR02), and of glucose (rCMRGI), and the uptake of 11C–methyl–L–methionine (11C–Met) were visually evaluated in lesions and compared with values for the contralateral white matter regions. PET findings were correlated with those of x–ray computed tomography (CT) and magnetic resonance imaging (MRI), and were analyzed for nontumor CNS diseases and cerebral gliomas. rCBF and rCBV were changeable from disease to disease or from stage to stage of disease progression. rOEF and rCMR02 remained low in 5 and 6, respectively, of 9 nontumor CNS diseases examined, whereas these parameters were increased in CNS infections such as brain abscess. Overall, noteworthy was the locally increased rOEF and rCMR02 in the patients with a brain abscess in contrast to the values for patients with gliomas. rCMRGI reflected biological characteristics of each disease, and correlated with cell density, whether reactive glial cells or inflammatory cells. 11C–Met was accumulated at a certain stage of nontumor CNS diseases, which implied uptake of the tracer as a result of disruption of the blood–brain barrier as well as metabolic incorporation.     

Clinical and cerebral FDG PET scan in a patient with Krabbe's disease

A 2-year, 6-month-old Saudi male with infantile Krabbe's disease was studied with fluorine-18-labeled-2-fluoro-2-deoxyglucose positron emission tomography (FDG PET) scan. The patient presented with a gradual loss of developmental milestones, irritability, and crying. At the advanced stage of the disease, he developed tonic-clonic seizures and became a microcephalic, extremely irritable, blind, spastic quadriplegic child, with no deep tendon reflexes. Laboratory studies revealed normal blood chemistry, muscle enzymes, very long chain fatty acids, and acylcarnitines. No abnormal urinary organic acids were detected. The cerebrospinal fluid protein concentration was increased. Magnetic resonance imaging of the brain revealed mild brain atrophy and white matter disease mainly in the centrum semiovale. Electroretinography was normal; however, electroencephalography and visual-evoked potentials were abnormal. Peripheral nerve conduction studies documented a demyelinating neuropathic process. The FDG PET study of the brain demonstrated a marked decrease in the metabolism of the left cerebral cortex and no uptake in the caudate heads. Normal glucose uptake was observed in the thalami, lentiform nuclei, and cerebellum. The patient did not present for subsequent clinic visits and is presumed dead.     

外伤性胼胝体损伤的MRI诊断

[目的] 观察颅脑创伤致胼胝体损伤的MRI表现,为临床提供有价值的诊断信息,提高颅脑创伤的救治水平. 方法 回顾分析临沂市人民医院神经外科自2007年至2009年收治疗的20例MRI证实为胼胝体损伤患者的临床、影像资料,观察其临床表现及MRI各序列特征. 结果 外伤性胼胝体损伤在临床较为少见,以非出血性损伤为主,损伤部位常见于体部及压部,少数位于膝部,嘴部损伤罕见.对于早期非出血性损伤,MRI常表现为稍长T1稍长T2信号,且常伴弥漫性轴索损伤的表现.在胼胝体损伤的中后期,胼胝体局部往往萎缩,病灶区易出现液化坏死,可有胶质瘢痕及软化灶形成,在MR/表现为长T1长T2信号,且信号强度近似于脑脊液,还可见相应部位的脑室扩大.在弥散加权成像(DWI)可见非出血性损伤在急性期和亚急性期呈高信号,随着时间延长,信号逐渐减低至正常脑组织信号,如形成软化灶,则表现为脑脊液信号. 结论 外伤性胼胝体损伤可引起严重后果,在重型颅脑损伤中并不罕见,应当引起临床医生重视.MRI是显示胼胝体损伤病灶最好的影像学检查手段,不仅对其微小病变敏感显示,且能够多方位地显示病变.     

Cerebral Aspergillosis with Multiple Enhancing Nodules in the Right Cerebral Hemisphere in the Immune-Competent Patient

Aspergillosis in the central nervous system (CNS) is a very rare disease in immune-competent patients. There was a case of a healthy man without a history of immune-compromised disease who had invasive aspergillosis with unusual radiologic findings. A 48-year-old healthy man with diabetes mellitus, presented with complaints of blurred vision that persisted for one month. Brain magnetic resonance imaging (MRI) showed multiple nodular enhancing lesions on the right cerebral hemisphere. The diffusion image appeared in a high-signal intensity in these areas. Cerebrospinal fluid examination did not show any infection signs. An open biopsy was done and intraoperative findings showed grayish inflammatory and necrotic tissue without a definitive mass lesion. The pathologic result was a brain abscess caused by fungal infection, morphologically aspergillus. Antifungal agents (Amphotericin B, Ambisome and Voriconazole) were used for treatment for 3 months. The visual symptoms improved. There was no recurrence or abscess pocket, but the remaining focal enhanced lesions were visible in the right temporal and occipital area at a one year follow-up MRI. This immune-competent patient showed multiple enhancing CNS aspergillosis in the cerebral hemisphere, which had a good outcome with antifungal agents.     

Clinicopathological characteristics of Creutzfeldt-Jakob disease with a PrP V180I mutation and M129V polymorphism on different alleles]

We report an 80-year-old Japanese man with histologically-diagnosed Creutzfeldt-Jakob disease (CJD). The patient was admitted to our neurological unit because of sudden onset motor aphasia-like symptoms and right hemiparesis. His medical and family histories were unremarkable, and he had taken no medications. Urine, blood counts and blood chemistry were all within normal limits. Cerebrospinal fluid was normal except for elevation of neuron specific enolase (29.9 ng/ml). High-signal intensity was demonstrated in the cortex of the left temporal lobe on T2-weighted MRI images, and the lesion swelled during the initial stage of the disease. There was no enhancement with Gd-DTPA. Serial MRI showed that the high-signal lesion had spread into the bilateral cerebral cortex. The patient developed myoclonus followed by akinetic mutism within 6 months of onset. Consecutive EEGs revealed no periodic synchronous discharge (PSD). He died of pneumonia 21 months after of admission. Autopsy revealed spongiform changes in the cerebral cortex with Kuru plaques, confirming the diagnosis of CJD. The Cerebellar cortex was well preserved. The high-signal lesions corresponded to the spongiform changes in the cerebral cortex. Immunohistochemical analysis showed weak synaptic prion staining. Prion protein (PrP) gene analysis of genomic DNA isolated from the autopsied brain by polymerase chain reaction, the restriction fragment length polymorphisms, and direct sequencing revealed a point mutation (Val-->Ile) at codon 180 and a polymorphism (Met/Val) at codon 129 on different alleles. A few CJD patients with point mutations in codon 180 of the PrP gene have been reported. Combination of the codon 180 point mutation and codon 129 polymorphism may yield an atypical clinicopathological form of CJD that includes late onset, negative PSD, and atypical MRI findings, with preservation of the cerebellar cortex.     

Diagnostic work-up in Whipple's disease with cerebral involvement

The diagnostic work-up in the case of a suspected cerebral involvement of Whipple's disease involves neuroimaging and analysis of cerebrospinal fluid (CSF) including polymerase chain reaction (PCR) assays for Tropheryma whipplei. As neurological findings may be complex and unspecific, extracerebral symptoms often lead to the suspicion of Whipple's disease. We report the cases of two patients in whom the suspected diagnosis of Whipple's disease could not be proved either by endoscopy or by the analysis of CSF. Only by means of a cerebral biopsy was the diagnosis assumed and specific therapy was initiated.