Cerebral FDG PET Research Articles

Differences and Similarities in Empathy Deficit and Its Neural Basis between Logopenic and Amnesic Alzheimer's Disease.

The aims of the study were to assess empathy deficit and neuronal correlates in logopenic primary progressive aphasia (lv-PPA) and compare these data with those deriving from amnesic Alzheimer's disease (AD). Eighteen lv-PPA and thirty-eight amnesic AD patients were included. Empathy in both cognitive and affective domains was assessed by Informer-rated Interpersonal Reactivity Index (perspective taking, PT, and fantasy, FT, for cognitive empathy; empathic concern, EC, and personal distress, PD, for affective empathy) before (T0) and after (T1) cognitive symptoms' onset. Emotion recognition was explored through the Ekman 60 Faces Test. Cerebral FDG-PET was used to explore neural correlates underlying empathy deficits. From T0 to T1, PT scores decreased, and PD scores increased in both lv-PPA (PT z = -3.43, p = 0.001; PD z = -3.62, p < 0.001) and in amnesic AD (PT z = -4.57, p < 0.001; PD z = -5.20, p < 0.001). Delta PT (T0-T1) negatively correlated with metabolic disfunction of the right superior temporal gyrus, fusiform gyrus, and middle frontal gyrus (MFG) in amnesic AD and of the left inferior parietal lobule (IPL), insula, MFG, and bilateral superior frontal gyrus (SFG) in lv-PPA (p < 0.005). Delta PD (T0-T1) positively correlated with metabolic disfunction of the right inferior frontal gyrus in amnesic AD (p < 0.001) and of the left IPL, insula, and bilateral SFG in lv-PPA (p < 0.005). Lv-PPA and amnesic AD share the same empathic changes, with a damage of cognitive empathy and a heightening of personal distress over time. The differences in metabolic disfunctions correlated with empathy deficits might be due to a different vulnerability of specific brain regions in the two AD clinical presentations.

Role of plaque inflammation in symptomatic carotid stenosis.

Prior studies have shown that plaque inflammation on FDG-PET and the symptomatic carotid atheroma inflammation lumen-stenosis (SCAIL) score were associated with recurrent ischemic events, but the findings have thus far not been widely validated. Therefore, we aimed to validate the findings of prior studies. A single-center prospective cohort study that recruited patients with (1) recent TIA or ischemic stroke within the past 30 days, (2) ipsilateral carotid artery stenosis of ≥50%, and (3) were not considered for early carotid revascularization. The (1) maximum standardized uptake value (SUVmax) of the symptomatic carotid plaque, (2) the SCAIL score, and (3) stenosis severity of the symptomatic carotid artery were measured for all patients. The outcomes were (1) a 90-day ipsilateral ischemic stroke and (2) a 90-day ipsilateral symptomatic TIA or major adverse cardiovascular event (MACE). Among the 131 patients included in the study, the commonest cardiovascular risk factor was hypertension (95 patients, 72.5%), followed by diabetes mellitus (77 patients, 58.8%) and being a current smoker (64 patients, 48.9%). The median (IQR) duration between the index cerebral ischemic event and recruitment to the study was 1 (0, 2.5) days. The median (IQR) duration between the index cerebral ischemic event and FDG-PET was 5 (4, 7) days. A total of 14 (10.7%) patients had a 90-day stroke, and 41 (31.3%) patients had a 90-day TIA or MACE. On comparison of the predictive performances of the SCAIL score and SUVmax, SUVmax was found to be superior to the SCAIL score for predicting both 90-day ipsilateral ischemic stroke (AUC: SCAIL = 0.79, SUVmax = 0.92; p < 0.001; 95% CI = 0.072, 0.229) and 90-day TIA or MACE (AUC: SCAIL = 0.76, SUVmax = 0.84; p = 0.009; 95% CI = 0.020, 0.143). Plaque inflammation as quantified on FDG-PET may serve as a reliable biomarker for risk stratification among patients with ECAD and recent TIA or ischemic stroke. Future studies should evaluate whether patients with significant plaque inflammation as quantified on FDG-PET benefit from carotid revascularization and/or anti-inflammatory therapy.

Different metabolic and clinical profiles between patients with pure Alzheimer dementia and epileptic Alzheimer dementia: a metabolic study

Aim: To investigate the clinical characteristics and cerebral FDG PET metabolisms of dementia patients who were also diagnosed with epilepsy and compare the differences with pure Alzheimer dementia patients.Methods: In this case-control study, a total of 14 patients, 7 patients with pure Alzheimer disease as a control group and 7 age and gender-matched patients with Alzheimer disease and concomitant epilepsy as a study group, were included. Detailed neurocognitive battery and brain fludeoxyglucose positron emission tomography (FDG PET-CT) were performed for all subjects.Results: In comparison of neurocognitive test scores, there was no significant difference between the study and control groups. However, geriatric depression scale scores were significantly lower in study group than the controls (p= 0.026). In cerebral FDG-PET CT profiles of subjects we detected significantly lower metabolism in left and right cerebellum, left lentiform nucleus, right thalamus and vermis in the study group (p=0.008, p=0.023, p=0.003, p=0.002, p=0.002, respectively). In the right parietotemporal cortex and right and left associative visual cortex, we found higher metabolism in the study group than controls (p=0.023, p=0.012, p=0.003, respectively).Conclusion: Epileptic patients with Alzheimer’s dementia may have distinct clinical and metabolic profiles, than pure Alzheimer’s disease patients. Even if there is no difference in the neurocognitive clinical scores of the patients, depression and related functional abnormalities may be a biomarker of epileptic AD.

Unravelling neural correlates of empathy deficits in Subjective Cognitive Decline, Mild Cognitive Impairment and Alzheimer’s Disease

Empathy is the ability to understand (cognitive empathy) and to feel (affective empathy) what others feel. The aim of the study was to assess empathy deficit and neuronal correlates in Subjective Cognitive Decline (SCD), Mild Cognitive Impairment (MCI) and Alzheimer’s Disease (AD) dementia. Twenty-four SCD, 41 MCI and 46 CE patients were included. Informer-rated Interpersonal Reactivity Index was used to explore cognitive (Perspective Taking-PT, Fantasy-FT) and affective (Empathic Concern-EC, Personal Distress-PD) empathy, before (T0) and after (T1) cognitive symptoms’ onset. Emotion recognition ability was tested through Ekman-60 Faces Test. Cerebral FDG-PET SPM analysis was used to explore neural correlates underlying empathy deficits. FT-T1 scores were lower in AD compared to SCD (13.0 ± 8.0 vs 19.1 ± 4,7 p = 0.008), PD-T1 score were higher in AD compared to MCI and to SCD (27.00 ± 10.00 vs 25.3 ± 5.9 vs 20.5 ± 5.6, p = 0.001). A positive correlation was found between PT-T1 and metabolic disfunction of right middle gyrus (MFG) in MCI and AD. In AD group, a positive correlation between PT-T1 and insula and superior temporal gyrus (STG) metabolism was detected. A negative correlation was found between PD-T1 and superior parietal lobule metabolism in MCI, and between PD-T1 and STG metabolism in AD. Impairment of cognitive empathy starts at MCI stage. Increase of PD starts from preclinical phases and seems to be to be dissociated from cognitive decline. Loss of PT is related to a progressive involvement starting from right MFG in prodromal stage, extending to insula and STG in dementia. Heightened emotional contagion is probably related to derangement of mirror neurons systems in parietal regions in prodromal stages, and to impairment of temporal emotion inhibition system in advanced phases. Further studies are needed to clarify if alterations in emotional contagion might be a predictive feature of a cognitive decline driven by AD.

Identification of a rare presenilin 1 single amino acid deletion mutation (F175del) with unusual amyloid-β processing effects

We report the novel presenilin 1 (PSEN1) single amino acid deletion mutation F175del. Comprehensive clinical work-up, including cerebral MRI, FDG-PET, and CSF analysis, was performed in a male who had developed forgetfulness at the age of 39. Alzheimer’s disease dementia was diagnosed according to established criteria. The index patient manifested rapid progressive dementia, seizures, and myoclonus, and a Pisa syndrome as a side effect of donepezil treatment. The PSEN1 mutation F175del was found on genetic testing. It was rendered very likely pathogenic as amyloid-β (Aβ) peptide 42 was elevated in a cell culture model compared to presenilin 1 wild-type controls. An additional, unusual increase in Aβ39 indicates a rarely observed product line deviation in the generation of the shorter Aβ species. Our observations extend the range of PSEN1 mutations to be considered in familial dementia. We demonstrate that deletion of a single conserved amino acid, which is very rare compared to missense mutations as the common cause for PSEN1-associated Alzheimer’s disease, can lead to an unusual profile of Aβ species.

Neural correlates of different behavioral response to transcranial direct current stimulation between patients in the unresponsive wakefulness syndrome and minimally conscious state.

In this study, we used event-related potential (ERP) and 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) to study the neural correlates of different behavioral response to transcranial direct current stimulation (tDCS) between patients in unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS). Thirteen patients (eight in UWS and five in MCS) underwent 20 anodal tDCS sessions of the left dorsolateral prefrontal cortex (DLPFC). Before tDCS, all the patients and six age-matched healthy subjects underwent a cerebral FDG-PET scan and ERP test. The coma recovery scale-revised (CRS-R) results revealed that after tDCS, a significant improvement was observed only in the MCS group. The ERP results supported that MCS patients preserved more high-order cortical information processing capacities. The residual brain metabolism in the left DLPFC in MCS patients supported that a residual brain activity in the stimulated area was necessary for a behavioral response to tDCS. Our study also demonstrated that the cerebral metabolic rates of glucose (CMRgl) ratios in intrinsic network were correlated significantly with CRS-R in MCS patients. In addition, the right prefrontal region might be another potential therapeutic target for MCS patients.

Cerebral FDG-PET Findings in a Patient with Limbic Encephalitis: an Important Aid to Localize the Affected Region and Support the Diagnosis of Autoimmune Encephalitis. (P2.2-012)

Cerebral FDG-PET Findings in a Patient with Limbic Encephalitis: an Important Aid to Localize the Affected Region and Support the Diagnosis of Autoimmune Encephalitis. (P2.2-012)

The Value of Regional Cerebral Blood Flow SPECT and FDG PET in Operculoinsular Epilepsy.

Operculoinsular epilepsy (OIE) can be challenging to diagnose. While the value of SPECT cerebral blood flow and PET F-FDG studies for presurgical evaluation of patients with medial temporal lobe epilepsy (MTLE) is well established, it remains unclear whether they can help identify an operculoinsular epileptic focus. This study assesses the value of interictal/ictal regional cerebral blood flow (rCBF) SPECT and FDG PET for OIE diagnosis. Eighteen patients with proven OIE who underwent interictal/ictal rCBF SPECT and/or FDG-PET prior to epilepsy surgery were identified from our clinical database and were compared with a group of 18 patients who underwent MTLE surgery. Regional cerebral blood flow SPECT and FDG PET images were reevaluated visually by an expert reader blind to clinical data. Interictal/ictal rCBF SPECT correctly identified an operculoinsular focus in 11 (65%) of 17 OIE patients and was misleading in 3 cases (18%). Secondary activation in areas connected to the insula was often observed. In the MTLE group, the area of maximal increased perfusion was congruent in 12 (75%) of 16 patients and extended to the ipsilateral insula in 1 patient. FDG PET findings were concordant with the epileptic focus in 8 (47%) of 17 OIE patients and were misleading in 4 (24%), whereas they were concordant in all MTLE patients. Interictal/ictal rCBF SPECT can identify a concordant operculoinsular focus in a significant proportion of OIE patients and offers a valuable diagnostic tool in nonlesional cases. By contrast, the value of interictal FDG PET in this population is more equivocal.

Cerebral FDG-PET Findings in Patients with Traumatic Disorders of Consciousness: Preliminary Results of a Pilot Study (P5.159)

Cerebral FDG-PET Findings in Patients with Traumatic Disorders of Consciousness: Preliminary Results of a Pilot Study (P5.159)

Independent value added by diffusion MRI for prediction of cognitive function in older adults.

The purpose of this study was to determine whether white matter microstructure measured by diffusion magnetic resonance imaging (dMRI) provides independent information about baseline level or change in executive function (EF) or memory (MEM) in older adults with and without cognitive impairment. Longitudinal data was acquired from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study from phases GO and 2 (2009–2015). ADNI participants included were diagnosed as cognitively normal (n = 46), early mild cognitive impairment (MCI) (n = 48), late MCI (n = 29), and dementia (n = 39) at baseline. We modeled the association between dMRI-based global white matter mean diffusivity (MD) and baseline level and change in EF and MEM composite scores, in models controlling for baseline bilateral hippocampal volume, regional cerebral FDG PET metabolism and global cerebral AV45 PET uptake. EF and MEM composite scores were measured at baseline, 6, 12, 24 and 36 months. In the baseline late MCI and dementia groups, greater global MD was associated with lesser baseline EF, but not EF change nor MEM baseline or change. As expected, lesser hippocampal volume and lesser FDG PET metabolism was associated with greater rates of EF and MEM decline. In ADNI-GO/2 participants, white matter integrity provided independent information about current executive function, but was not sensitive to future cognitive change. Since individuals experiencing executive function declines progress to dementia more rapidly than those with only memory impairment, better biomarkers of future executive function decline are needed.

Cerebral FDG-PET Findings in Patients with Traumatic Disorders of Consciousness: Preliminary Results of a Pilot Study

Cerebral FDG-PET Findings in Patients with Traumatic Disorders of Consciousness: Preliminary Results of a Pilot Study

Cerebral 18FluoroDeoxy-Glucose Positron Emission Tomography in paediatric anti N-methyl-d-aspartate receptor encephalitis: A case series

BackgroundAnti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a frequent and severe cause of encephalitis in children with potential efficient treatment (immunotherapy). Suggestive clinical features are behavioural troubles, seizures and movement disorders. Prompt diagnosis and treatment initiation are needed to guarantee favourable outcome. Nevertheless, diagnosis may be challenging because of the classical ancillary test (magnetic resonance imaging (MRI), electroencephalogram, standard cerebro-spinal fluid analysis) have limited sensitivity. Currently, immunological analyses are needed for the diagnostic confirmation. In adult patients, some studies suggested a potential role of cerebral 18FluoroDeoxy-Glucose Positron Emission Tomography (FDG-PET) in the evaluation of anti-NMDAR encephalitis. Nevertheless, almost no data exist in paediatric population. MethodWe report retrospectively clinical, ancillary tests and cerebral FDG-PET data in 6 young patients (median age=10.5years, 4 girls) with immunologically confirmed anti-NMDAR encephalitis. ResultsOur patients presented classical clinical features of anti-NMDAR encephalitis with severe course (notably four patients had normal MRI). Our series shows the feasibility and the good sensitivity of cerebral FDG-PET (6/6 patients with brain metabolism alteration) in paediatric population. We report some particular features in this population: extensive, symmetric cortical hypometabolism especially in posterior areas; asymmetric anterior focus of hypermetabolism; and basal ganglia hypermetabolism. We found also a good correlation between the clinical severity and the cerebral metabolism changes. Moreover, serial cerebral FDG-PET showed parallel brain metabolism and clinical improvement. ConclusionOur study reveals the existence of specific patterns of brain metabolism alteration in anti-NMDAR encephalitis in paediatric population.

Postoperative cerebral glucose metabolism in pediatric patients receiving proton therapy for craniopharyngioma.

OBJECT The aim of the study was to document postoperative cerebral glucose distribution before proton therapy using F-18 fluorodeoxyglucose positron emission tomography (FDG PET) in children with craniopharyngioma. METHODS Between August 2011 and April 2014, 50 patients (20 males, 30 females) enrolled in a prospective trial for craniopharyngioma underwent FDG PET imaging before proton therapy. Proton therapy was delivered using doublescattered beams with a total prescribed dose of 54 cobalt gray equivalent. Tracer uptake in each of 63 anatomical regions was computed after warping PET images to a 3D reference template in Talairach coordinates. Regional uptake was deemed significantly low or high if it exceeded age-corresponding 95% prediction intervals of the normal population. The reference group included 132 children with non-CNS-related diseases and normal-appearing cerebral FDG PET scans. RESULTS Median patient age at diagnosis was 8.5 years (range 2-18 years). Forty-eight patients underwent 1-4 tumor-related surgeries before proton therapy, including placement of an Ommaya reservoir in 14 patients. Sixteen patients had symptomatic hydrocephalus that was treated with temporary (external ventricular drain, n = 16) or permanent CSF shunting (ventriculoperitoneal shunt, n = 1). The most commonly seen PET abnormalities in patients before proton therapy were significantly reduced uptake in subregions of the frontal lobe (often involving more than 1 gyrus), medial and ventral portions of the temporal lobe, cingulate gyrus, and caudate nucleus. A significantly high uptake was frequently observed on the contralateral side, including the superior, medial, and inferior temporal gyri and a large portion of the parietal lobe. Statistically significant predictor variables identified in the multivariate analysis for the extent of hypometabolism were sex (p = 0.005), hydrocephalus (p = 0.026), and the number of tumor-related surgeries (p = 0.017). CONCLUSIONS Postoperative FDG PET of patients with craniopharyngioma revealed metabolic abnormalities in specific regions of the brain. The ability to identify anatomical metabolic defects in individual patients facilitates the investigation of brain injury in children with craniopharyngioma.

Preliminary Study of Brain Glucose Metabolism Changes in Patients with Lung Cancer of Different Histological Types

Background:Cerebral glucose metabolism changes are always observed in patients suffering from malignant tumors. This preliminary study aimed to investigate the brain glucose metabolism changes in patients with lung cancer of different histological types.Methods:One hundred and twenty patients with primary untreated lung cancer, who visited People's Hospital of Zhengzhou University from February 2012 to July 2013, were divided into three groups based on histological types confirmed by biopsy or surgical pathology, which included adenocarcinoma (52 cases), squamous cell carcinoma (43 cases), and small-cell carcinoma (25 cases). The whole body 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) of these cases was retrospectively studied. The brain PET data of three groups were analyzed individually using statistical parametric maps (SPM) software, with 50 age-matched and gender-matched healthy controls for comparison.Results:The brain resting glucose metabolism in all three lung cancer groups showed regional cerebral metabolic reduction. The hypo-metabolic cerebral regions were mainly distributed at the left superior and middle frontal, bilateral superior and middle temporal and inferior and middle temporal gyrus. Besides, the hypo-metabolic regions were also found in the right inferior parietal lobule and hippocampus in the small-cell carcinoma group. The area of the total hypo-metabolic cerebral regions in the small-cell carcinoma group (total voxel value 3255) was larger than those in the adenocarcinoma group (total voxel value 1217) and squamous cell carcinoma group (total voxel value 1292).Conclusions:The brain resting glucose metabolism in patients with lung cancer shows regional cerebral metabolic reduction and the brain hypo-metabolic changes are related to the histological types of lung cancer.

Normal cerebral FDG uptake during childhood

Current understanding of cerebral FDG uptake during childhood originates from a small number of studies in patients with neurological abnormalities. Our aim was to describe cerebral FDG uptake in a dataset of FDG PET scans in children more likely to represent a normal population. We reviewed cerebral FDG PET scans in children up to 16 years of age with suspected/proven extracranial malignancies and the following exclusions: central nervous system metastases, previous malignancies, previous chemotherapy or radiotherapy, development of cerebral metastases during therapy, neurological conditions, taking antiepileptic medication or medications likely to interfere with cerebral metabolism, and general anaesthesia within 24 h. White matter, basal ganglia, thalamus and the cerebellar cortex were analysed using regional SUV(max), and the cerebral cortex, basal ganglia, thalamus and cerebellum were analysed using a regional relative uptake analysis in comparison to maximal cortical uptake. Scans from 30 patients (age range 11 months to 16 years, mean age 10 years 5 months) were included. All regions showed increasing SUV(max) with age. The parietal, occipital, lateral temporal and medial temporal lobes showed lower rates of increasing FDG uptake causing changing patterns of regional FDG uptake during childhood. The cortical regions showing the most intense uptake in early childhood were the parietal and occipital lobes. At approximately 7 years of age these regions had relatively less uptake than the frontal lobes and at approximately 10 years of age these regions had relatively less uptake than the thalamus. Relative FDG uptake in the brain has not reached an adult pattern by 1 year of age, but continues to change up to 16 years of age. The changing pattern is due to different regional rates of increasing cortical FDG uptake, which is less rapid in the parietal, occipital and temporal lobes than in the frontal lobes.

Cerebral glucose metabolism on positron emission tomography of children

Establishing the normative range of age-dependent fluorodeoxyglucose (FDG) uptake in the developing brain is necessary for understanding regional quantitative analysis of positron emission tomography (PET) brain images in children and also to provide functional information on brain development. We analyzed head sections of FDG PET/computed tomography (CT) images for 115 patients (5 months to 23 years) without central nervous system disease before treatment, as PET studies are not performed on healthy children owing to ethical considerations and the risk of radiation exposure. We investigated the changes in FDG uptake and established age-associated normative ranges of cerebral FDG. Head sections of FDG PET/CT images were registered to a population-based probabilistic atlas of human cortical structures. Gray matter of 56 brain structures was defined on normalized PET images according to the atlas. To avoid individual and experimental confounding factors, the relative standardized uptake value (SUV) over the cerebellum of each structure was calculated. Relative SUVs were analyzed by ANOVA and modeled using generalized estimating equalization analysis with false discovery rate control. Age and structure were significant factors affecting SUVs. Anatomic proximity had little effect on FDG uptake. Linear and quadratic developmental trajectories were observed on absolute and relative SUVs, respectively. An increase from posterior-to-anterior and superior-to-inferior pattern was observed in both absolute SUV increase rate and relative SUV peak age. The SUV of each structure was modeled with respect to age, and these models can serve as baselines for the quantitative analysis of cerebral FDG-PET images of children.

Cerebral FDG Metabolic Pattern in Pediatric Patients with Neurofibromatosis Type 1: A Retrospective Study

154 Objectives About 65% of NF1 children perform below chronologic age in school and 45% of them require special education assistance between the ages of 8 and 16 years. The cognitive phenotype of NF1 pediatric patients is not well understood. We retrospectively evaluated the cerebral FDG PET of NF1 pediatric patients using voxel-based statistical analysis. Methods Six NF1 patients (5 male, 1 female median age 13) underwent whole-body FDG PET/CT (Gemini TF, Philips Healthcare) including the brain, for evaluation of extra-cranial neoplasm. Their brain PET images were extracted from the whole-body images and compared with those of a comparison set consisting of 21 pediatric patients using Statistical Parametric Mapping SPM8 software (Wellcome Department of Cognitive Neurology, University College London, UK). The comparison set subjects underwent PET/CT for extracranial neoplasm not related to NF1, had no history of brain tumor or neurolopsychologic disease and had not received chemotherapy prior to PET/CT. SPM parameters included a 6 mm smoothing kernel, proportional scaling of global counts and a two-sample t test. Significant differences between groups were examined at p Results Compared with the comparison set, the 6 NF1 pediatric patients showed large (> 500 voxels) symmetric hypometabolic clusters in both thalami and caudate nuclei as well as large asymmetric clusters in the right medial frontal lobe and left occipital lobe. At smaller clusters (100-500 voxels), additional hypometabolic clusters were present in bilateral temporal lobe along the posterior horn, right greater than left, suggestive of the optic radiation pathway. Conclusions The striking FDG reductions of the bilateral thalamus and caudate nucleus in children is consistent with previous studies. The reduced metabolism in the occipital lobe and along the presumed bilateral optic radiations may explain the visuospacial deficits typically seen in NF1 children

Two Different 18F-FDG Brain PET Metabolic Patterns in Autoimmune Limbic Encephalitis

Autoimmune limbic encephalitis (ALE) is a severe, but treatable, neuropsychiatric disorder that is difficult to diagnose clinically. With the goal of improving diagnosis of this disorder, we retrospectively evaluated the cerebral FDG PET pattern in a group of patients with ALE. Nine adult patients with subacute cognitive decline were eventually diagnosed with ALE based on clinical presentation, cerebrospinal fluid inflammatory markers, and response to immunosuppressive therapy. All patients received FDG PET brain scanning during their diagnostic evaluation, which were retrospectively reviewed for this study. Our patients' scans fell into 2 readily separable patterns. Five younger patients had a mixed metabolic pattern most easily recognized by pronounced occipital hypometabolism, accentuated by hypermetabolism in the temporal and orbitofrontal cortex. Other, milder findings were also present. Once this unusual pattern was established as corresponding to ALE, it helped lead to the correct clinical diagnosis in the last 2 patients. Four older patients had scans that closely resembled diffuse neurodegenerative disease. We found 2 different PET scan patterns in patients with ALE. One is an easily recognizable mixture of hyper- and hypometabolism that has also been described in a few recent case reports and is potentially specific for ALE. The other is indistinguishable from neurodegenerative disease. We propose that awareness of these patterns may contribute to the diagnosis of this elusive, but treatable, neurologic disorder.

Cerebral FDG Metabolic Pattern in Pediatric Patients with Neurofibromatosis Type 1: A Retrospective Study

154 Objectives About 65% of NF1 children perform below chronologic age in school and 45% of them require special education assistance between the ages of 8 and 16 years. The cognitive phenotype of NF1 pediatric patients is not well understood. We retrospectively evaluated the cerebral FDG PET of NF1 pediatric patients using voxel-based statistical analysis. Methods Six NF1 patients (5 male, 1 female median age 13) underwent whole-body FDG PET/CT (Gemini TF, Philips Healthcare) including the brain, for evaluation of extra-cranial neoplasm. Their brain PET images were extracted from the whole-body images and compared with those of a comparison set consisting of 21 pediatric patients using Statistical Parametric Mapping SPM8 software (Wellcome Department of Cognitive Neurology, University College London, UK). The comparison set subjects underwent PET/CT for extracranial neoplasm not related to NF1, had no history of brain tumor or neurolopsychologic disease and had not received chemotherapy prior to PET/CT. SPM parameters included a 6 mm smoothing kernel, proportional scaling of global counts and a two-sample t test. Significant differences between groups were examined at p Results Compared with the comparison set, the 6 NF1 pediatric patients showed large (> 500 voxels) symmetric hypometabolic clusters in both thalami and caudate nuclei as well as large asymmetric clusters in the right medial frontal lobe and left occipital lobe. At smaller clusters (100-500 voxels), additional hypometabolic clusters were present in bilateral temporal lobe along the posterior horn, right greater than left, suggestive of the optic radiation pathway. Conclusions The striking FDG reductions of the bilateral thalamus and caudate nucleus in children is consistent with previous studies. The reduced metabolism in the occipital lobe and along the presumed bilateral optic radiations may explain the visuospacial deficits typically seen in NF1 children

Dynamic FDG PET for assessing early effects of cerebral hypoxia and resuscitation in new-born pigs

Changes in cerebral glucose metabolism may be an early prognostic indicator of perinatal hypoxic-ischaemic injury. In this study dynamic ¹⁸F-FDG PET was used to evaluate cerebral glucose metabolism in piglets after global perinatal hypoxia and the impact of the resuscitation strategy using room air or hyperoxia. New-born piglets (n = 16) underwent 60 min of global hypoxia followed by 30 min of resuscitation with a fraction of inspired oxygen (FiO₂) of 0.21 or 1.0. Dynamic FDG PET, using a microPET system, was performed at baseline and repeated at the end of resuscitation under stabilized haemodynamic conditions. MRI at 3 T was performed for anatomic correlation. Global and regional cerebral metabolic rates of glucose (CMRgl) were assessed by Patlak analysis for the two time-points and resuscitation groups. Global hypoxia was found to cause an immediate decrease in cerebral glucose metabolism from a baseline level (mean ± SD) of 21.2 ± 7.9 to 12.6 ± 4.7 μmol/min/ 100 g (p <0.01). The basal ganglia, cerebellum and cortex showed the greatest decrease in CMRgl but no significant differences in global or regional CMRgl between the resuscitation groups were found. Dynamic FDG PET detected decreased cerebral glucose metabolism early after perinatal hypoxia in piglets. The decrease in CMRgl may indicate early changes of mild cerebral hypoxia-ischaemia. No significant effect of hyperoxic resuscitation on the degree of hypometabolism was found in this early phase after hypoxia. Cerebral FDG PET can provide new insights into mechanisms of perinatal hypoxic- ischaemic injury where early detection plays an important role in instituting therapy.