Comparison of consistency in centiloid scale among different analytical methods in amyloid PET: the CapAIBL, VIZCalc, and Amyquant methods

OBJECTIVE

The Centiloid (CL) scale is a standardized measure for quantifying amyloid deposition in amyloid positron emission tomography (PET) imaging. We aimed to assess the agreement among 3 CL calculation methods: CapAIBL, VIZCalc, and Amyquant.

METHODS

This study included 192 participants (mean age: 71.5 years, range: 50-87 years), comprising 55 with Alzheimer's disease, 65 with mild cognitive impairment, 13 with non-Alzheimer's dementia, and 59 cognitively normal participants. All the participants were assessed using the three CL calculation methods. Spearman's rank correlation, linear regression, Friedman tests, Wilcoxon signed-rank tests, and Bland-Altman analysis were employed to assess data correlations, linear associations, method differences, and systematic bias, respectively.

RESULTS

Strong correlations (rho = 0.99, p < .001) were observed among the CL values calculated using the three methods. Scatter plots and regression lines visually confirmed these strong correlations and met the validation criteria. Despite the robust correlations, a significant difference in CL value between CapAIBL and Amyquant was observed (36.1 ± 39.7 vs. 34.9 ± 39.4; p < .001). In contrast, no significant differences were found between CapAIBL and VIZCalc or between VIZCalc and Amyquant. The Bland-Altman analysis showed no observable systematic bias between the methods.

CONCLUSIONS

The study demonstrated strong agreement among the three methods for calculating CL values. Despite minor variations in the absolute values of the Centiloid scores obtained using these methods, the overall agreement suggests that they are interchangeable.

Moderating effect of age on the relationship between physical health loss and emotional distress post-acute care in Japanese older hospitalized patients

BACKGROUND

At present, there are no consistent findings regarding the association between physical health loss and mental health in older adults. Some studies have shown that physical health loss is a risk factor for worsening of mental health. Other studies revealed that declining physical health does not worsen mental health. This study aimed to clarify whether the relationship between physical health loss and emotional distress varies with age in older inpatients post receiving acute care.

METHODS

Data for this study were collected from 590 hospitalized patients aged ≥ 65 years immediately after their transfer from an acute care ward to a community-based integrated care ward. Emotional distress, post-acute care physical function, and cognitive function were assessed using established questionnaires and observations, whereas preadmission physical function was assessed by the family members of the patients. After conducting a one-way analysis of variance (ANOVA) and correlation analysis by age group for the main variables, a hierarchical multiple regression analysis was conducted with emotional distress as the dependent variable, physical function as the independent variable, age as the moderator variable, and cognitive and preadmission physical function as control variables.

RESULTS

The mean GDS-15 score was found to be 6.7 ± 3.8. Emotional distress showed a significant negative correlation with physical function in younger age groups (65-79 and 80-84 years); however, no such association was found in older age groups (85-89, and ≥ 90 years). Age moderated the association between physical function and emotional distress. Poor physical function was associated with higher emotional distress in the younger patients; however, no such association was observed in the older patients.

CONCLUSIONS

Age has a moderating effect on the relationship between physical health loss and increased emotional distress in older inpatients after acute care. It was suggested that even with the same degree of physical health loss, mental damage differed depending on age, with older patients experiencing less damage.

Clinico-imaging features of subjects at risk of Lewy body disease in NaT-PROBE baseline analysis

Individuals with prodromal symptoms of Lewy body disease (LBD), such as rapid eye movement sleep behavior disorder (RBD), often showed imaging defects similar to patients with Parkinson's disease and dementia with Lewy bodies. We examined dopamine transporter (DaT) single-photon-emission computed tomography (SPECT) and metaiodobenzylguanidine (MIBG) scintigraphy in 69 high-risk subjects with ≥2 prodromal symptoms (dysautonomia, hyposmia, and probable RBD) and 32 low-risk subjects without prodromal symptoms, whom were identified through a questionnaire survey of health checkup examinees. The high-risk subjects had significantly worse scores on Stroop test, line orientation test, and the Odor Stick Identification Test for Japanese than the low-risk subjects. The prevalence of abnormalities on DaT-SPECT was higher in the high-risk group than in the low-risk group (24.6% vs. 6.3%, p = 0.030). A decreased uptake on DaT-SPECT was associated with motor impairment, and MIBG scintigraphy defects were associated with hyposmia. The simultaneous evaluation of DaT-SPECT and MIBG scintigraphy may capture a wide range of individuals with prodromal LBD.

Prediction of Nursing Home Admission Using the FRAIL-NH Scale Among Older Adults in Post-Acute Care Settings

OBJECTIVES

The FRAIL-NH scale was developed to identify frailty status in nursing home residents. The purpose of this study was to examine the utility of the FRAIL-NH scale for predicting nursing home admission among patients in post-acute care settings. Design/ Setting/ Participants: This single-center, prospective, observational cohort study included participants aged 65 years or older who were admitted to a community-based integrated care ward (CICW) between July 2015 and November 2020.

MEASUREMENTS

Using the CICW database, we retrospectively classified participants as robust, prefrail, or frail based on the FRAIL-NH scale the score by identifying variables from our database that were most representative of each component. The following data were collected: examination findings, CICW admission and discharge information, length of CICW stay, and nursing home admission. The participants were divided into two groups based on whether or not they were admitted to a nursing home after CICW discharge. The hazard ratios (HRs) and 95% confidence intervals (CIs) for nursing home admission were calculated according to the FRAIL-NH categories using the Cox proportional hazards models with reference to the robust group. In the multivariate adjusted model, we adjusted for age, sex, nutritional status, cognitive function, living status, and economic status.

RESULTS

Data of 550 older adults were analyzed, of which 118 were admitted and 432 were not admitted to a nursing home. The frail group had a higher risk of nursing home admission (HR, 2.22; 95% CI 1.32-3.76) than the robust group.

CONCLUSIONS

This study showed that the FRAIL-NH scale was beneficial for predicting nursing home admission among older adults in the post-acute care setting. Thus, assessment using the FRAIL-NH scale may help to consider preparation and support for life after discharge.

Age-related increase of monoamine oxidase B in amyloid-negative cognitively unimpaired elderly subjects

OBJECTIVE

Monoamine oxidase B (MAO-B) is highly abundant in reactive astrocytes and upregulated in neuroinflammatory processes. However, the age-related change of MAO-B in amyloid-negative cognitively unimpaired elderly subjects has not yet been sufficiently evaluated on positron emission tomography (PET). ¹⁸F-THK5351 is a radiotracer with high affinity to MAO-B, which may potentially serve as an imaging biomarker for detecting neuroinflammation. The purpose of this study was to investigate the age-related topographic change of ¹⁸F-THK5351 PET in amyloid-negative cognitively unimpaired elderly subjects.

METHODS

The age-related change of ¹⁸F-THK5351 retention was evaluated on the visual analysis, voxel and region of interest (ROI)-based analyses using Statistical Parametric Mapping and PETSurfer tool of FreeSurfer in 31 amyloid-negative cognitively unimpaired elderly subjects.

RESULTS

On visual inspection, elderly groups showed the spread of ¹⁸F-THK5351 accumulation from the medial to inferolateral temporal and basal frontal lobes, and cingulate gyrus. Additionally, voxel- and ROI-based analysis demonstrated the correlation between ¹⁸F-THK5351 accumulation and participants' age, especially in the inferior temporal lobes.

CONCLUSIONS

This study demonstrated age-dependent increase of ¹⁸F-THK5351 retention in amyloid-negative cognitively unimpaired subjects, which suggests an increase in MAO-B positive reactive astrocytes with aging.

Patterns of Distribution of 18F-THK5351 Positron Emission Tomography in Alzheimer's Disease Continuum

BACKGROUND

Alzheimer's disease (AD) is conceptualized as a biological continuum encompassing the preclinical (clinically asymptomatic but with evidence of AD pathology) and clinical (symptomatic) phases.

OBJECTIVE

Using 18F-THK5351 as a tracer that binds to both tau and MAO-B, we investigated the changes in 18F-THK5351 accumulation patterns in AD continuum individuals with positive amyloid PET consisting of cognitively normal individuals (CNp), amnestic mild cognitive impairment (aMCI), and AD and cognitively normal individuals (CNn) with negative amyloid PET.

METHODS

We studied 69 individuals (32 CNn, 11 CNp, 9 aMCI, and 17 AD) with structural magnetic resonance imaging, 11C-Pittsburgh compound-B (PIB) and 18F-THK5351 PET, and neuropsychological assessment. 18F-THK5351 accumulation was evaluated with visual analysis, voxel-based analysis and combined region of interest (ROI)-based analysis corresponding to Braak neurofibrillary tangle stage.

RESULTS

On visual analysis, 18F-THK5351 accumulation was increased with stage progression in the AD continuum. On voxel-based analysis, there was no statistical difference in 18F-THK5351 accumulation between CNp and CNn. However, a slight increase of the bilateral posterior cingulate gyrus in aMCI and definite increase of the bilateral parietal temporal association area and posterior cingulate gyrus/precuneus in AD were detected compared with CNn. On ROI-based analyses, 18F-THK5351 accumulation correlated positively with supratentorial 11C-PIB accumulation and negatively with the hippocampal volume and neuropsychological assessment.

CONCLUSION

The AD continuum showed an increase in 18F-THK5351 with stage progression, suggesting that 18F-THK5351 has the potential to visualize the severity of tau deposition and neurodegeneration in accordance with the AD continuum.

A Japanese Multicenter Study on PET and Other Biomarkers for Subjects with Potential Preclinical and Prodromal Alzheimer's Disease

BACKGROUND

PET (positron emission tomography) and CSF (cerebrospinal fluid) provide the "ATN" (Amyloid, Tau, Neurodegeneration) classification and play an essential role in early and differential diagnosis of Alzheimer's disease (AD).

OBJECTIVE

Biomarkers were evaluated in a Japanese multicenter study on cognitively unimpaired subjects (CU) and early (E) and late (L) mild cognitive impairment (MCI) patients.

MEASUREMENTS

A total of 38 (26 CU, 7 EMCI, 5 LMCI) subjects with the age of 65-84 were enrolled. Amyloid-PET and FDG-PET as well as structural MRI were acquired on all of them, with an additional tau-PET with 18F-flortaucipir on 15 and CSF measurement of Aβ1-42, P-tau, and T-tau on 18 subjects. Positivity of amyloid and tau was determined based on the positive result of either PET or CSF.

RESULTS

The amyloid positivity was 13/38, with discordance between PET and CSF in 6/18. Cortical tau deposition quantified with PET was significantly correlated with CSF P-tau, in spite of discordance in the binary positivity between visual PET interpretation and CSF P-tau in 5/8 (PET-/CSF+). Tau was positive in 7/9 amyloid positive and 8/16 amyloid negative subjects who underwent tau measurement, respectively. Overall, a large number of subjects presented quantitative measures and/or visual read that are close to the borderline of binary positivity, which caused, at least partly, the discordance between PET and CSF in amyloid and/or tau. Nine subjects presented either tau or FDG-PET positive while amyloid was negative, suggesting the possibility of non-AD disorders.

CONCLUSION

Positivity rate of amyloid and tau, together with their relationship, was consistent with previous reports. Multicenter study on subjects with very mild or no cognitive impairment may need refining the positivity criteria and cutoff level as well as strict quality control of the measurements.

Plasma Amyloid-β Biomarker Associated with Cognitive Decline in Preclinical Alzheimer's Disease

BACKGROUND

Using immunoprecipitation-mass spectrometry, we recently developed and validated a plasma composite biomarker for the assessment of amyloid-β (Aβ) levels. However, as yet, its relationship with clinical outcomes remains unclear.

OBJECTIVE

We aimed to examine the relationship between this plasma Aβ composite biomarker and cognitive function in cognitively normal older adults in two independent cohorts.

METHODS

Participants enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study and the National Centre for Geriatrics and Gerontology (NCGG) study had undergone Aβ neuroimaging using positron emission tomography (PET), cognitive assessments and provided blood samples. We derived a high-performance plasma Aβ composite biomarker by immunoprecipitation with mass-spectrometry.

RESULTS

Both continuous and categorical measures of the plasma Aβ composite biomarker were significantly related to decline in episodic memory and executive function. The magnitude of effects of the plasma Aβ composite on episodic memory and executive function were comparable to that observed for the effects of PET Aβ levels on these same outcome measures.

CONCLUSION

Several plasma Aβ biomarkers have been developed, but none have yet been applied to investigate their relationship with cognitive outcomes. Our results have important implications for the use of this biomarker in the detection of at-risk individuals.

An evaluation of the amyloid cascade model using in vivo positron emission tomographic imaging

AIM

The amyloid cascade hypothesis posits that the accumulation of amyloid β (Aβ) is the triggering factor for Alzheimer's disease, which consecutively induces aggregation of tau, synaptic loss, and cell death. Most experimental and clinical evidence supports this model, but the available data are largely qualitative. Here, we tested the amyloid cascade hypothesis by using in vivo evaluation of positron emission tomography and magnetic resonance imaging.

METHODS

Path analysis was used to estimate the relationships among Aβ accumulation (PiB standardized uptake value ratio (SUVR)), tau aggregation and its related neuroinflammation (THK5351 SUVR), grey matter atrophy in the medial temporal region, and memory function in Aβ-positive subjects. We also performed additional regression analyses to evaluate the effect of Aβ on the toxicity of tau aggregation/neuroinflammation.

RESULTS

Path analysis supported our hypothesized model: Aβ accumulation affected tau aggregation/neuroinflammation in the medial temporal region, and these pathological changes caused of the grey matter atrophy and memory dysfunction. In separate regression analyses, THK5351 SUVR had a significant effect on grey matter atrophy only in PiB-positive subjects. The analysis of the interaction effect showed that the effects of THK5351 SUVR on grey matter atrophy were significantly different between PiB-positive and PiB-negative groups. When we included the effect of being an apolipoprotein E ε4 carrier as a covariate, the interaction effect remained significant.

CONCLUSION

Our in vivo evaluation of positron emission tomographic and magnetic resonance imaging data supported the amyloid cascade hypothesis. In addition, it indicated that Aβ not only accelerates tau aggregation/neuroinflammation but promotes its toxicity. Our findings showed the importance of understanding the role and therapeutic potential of the interaction between amyloid and tau aggregation/neuroinflammation in Alzheimer's disease.

Unclassified four-repeat tauopathy associated with familial parkinsonism and progressive respiratory failure

We describe an autopsied patient with familial parkinsonism and unclassified four repeat-tau (4R-tau) aggregation. She presented with bradykinesia, truncal dystonia, and mild amnesia at the age of 61 and then exhibited body weight loss (15 kg over 8 months), sleep disturbances, and progressive respiratory failure with CO₂ narcosis. She died of respiratory failure at the age of 62, 14 months after disease onset. Her brother also showed parkinsonism at the age of 58 and suddenly died 6 months later. Postmortem examination revealed 4R-tau aggregation, which was characterized by neuronal globose-type tangles or pretangles, bush-like or miscellaneous astrocytic inclusions, and coiled bodies. The temporal tip, the striatum, the substantia nigra, the tegmentum of the midbrain, the medullary reticular formation, and the spinal cord were severely involved with tau aggregation. Argyrophilic grains and ballooned neurons were also found in the medial temporal structures, however, extensions of the 4R-aggregations in the case were clearly broader than those of the argyrophilic grains. Western blot analysis of sarkosyl-insoluble fractions from brain lysates revealed prominent bands of tau at both 33 kDa and 37 kDa. Genetic examinations did not reveal any known pathogenic mutations in MAPT, DCTN-1, PSEN-1, or familial or young-onset parkinsonism-related genes. The clinical manifestations, pathologic findings, and biochemical properties of aggregated tau in our patient cannot be explained by argyrophilic grain disease or other known 4R-tauopathies alone. Our results further extend the clinical and neuropathologic spectra of 4R-tauopathy.

Electromagnetic signatures of the preclinical and prodromal stages of Alzheimer's disease

Biomarkers useful for the predementia stages of Alzheimer’s disease are needed. Electroencephalography and magnetoencephalography (MEG) are expected to provide potential biomarker candidates for evaluating the predementia stages of Alzheimer’s disease. However, the physiological relevance of EEG/MEG signal changes and their role in pathophysiological processes such as amyloid-β deposition and neurodegeneration need to be elucidated. We evaluated 28 individuals with mild cognitive impairment and 38 cognitively normal individuals, all of whom were further classified into amyloid-β-positive mild cognitive impairment (n = 17, mean age 74.7 ± 5.4 years, nine males), amyloid-β-negative mild cognitive impairment (n = 11, mean age 73.8 ± 8.8 years, eight males), amyloid-β-positive cognitively normal (n = 13, mean age 71.8 ± 4.4 years, seven males), and amyloid-β-negative cognitively normal (n = 25, mean age 72.5 ± 3.4 years, 11 males) individuals using Pittsburgh compound B-PET. We measured resting state MEG for 5 min with the eyes closed, and investigated regional spectral patterns of MEG signals using atlas-based region of interest analysis. Then, the relevance of the regional spectral patterns and their associations with pathophysiological backgrounds were analysed by integrating information from Pittsburgh compound B-PET, fluorodeoxyglucose-PET, structural MRI, and cognitive tests. The results demonstrated that regional spectral patterns of resting state activity could be separated into several types of MEG signatures as follows: (i) the effects of amyloid-β deposition were expressed as the alpha band power augmentation in medial frontal areas; (ii) the delta band power increase in the same region was associated with disease progression within the Alzheimer’s disease continuum and was correlated with entorhinal atrophy and an Alzheimer’s disease-like regional decrease in glucose metabolism; and (iii) the global theta power augmentation, which was previously considered to be an Alzheimer’s disease-related EEG/MEG signature, was associated with general cognitive decline and hippocampal atrophy, but was not specific to Alzheimer’s disease because these changes could be observed in the absence of amyloid-β deposition. The results suggest that these MEG signatures may be useful as unique biomarkers for the predementia stages of Alzheimer’s disease.

Decreased Glucose Metabolism in Medial Prefrontal Areas is Associated with Nutritional Status in Patients with Prodromal and Early Alzheimer's Disease

BACKGROUND

Weight loss is frequently observed in patients with Alzheimer's disease (AD); however, the underlying mechanisms are not well understood.

OBJECTS

To clarify the associations between nutritional status and AD-related brain changes using Pittsburgh Compound-B (PiB)-PET, fluorodeoxyglucose (FDG)-PET, and structural MRI.

METHODS

The subjects were 34 amyloid-β (Aβ)-positive individuals with mild cognitive impairment or early AD (prodromal/early AD), and 55 Aβ-negative cognitively normal (CN) subjects who attended the Multimodal Neuroimaging for AD Diagnosis (MULNIAD) study. Nutritional status of the subjects was assessed by body mass index and waist to height ratio (waist circumference/height). The associations between nutritional status and brain changes were examined by multiple regression analysis using statistical parametric mapping.

RESULTS

In the prodromal/early AD group, nutritional status was significantly positively correlated with regional cerebral glucose metabolism (rCGM) in the medial prefrontal cortices, while different topographical associations were seen in the CN group, suggesting these changes were AD-specific. Aβ deposition and gray matter volume were not significantly associated with nutritional status. Sub-analysis in the prodromal/early AD group demonstrated that fat mass index, but not fat-free mass index, was positively correlated with rCGM in the medial prefrontal areas.

CONCLUSION

This present study provides preliminary results suggesting that hypometabolism in the medial prefrontal areas is specifically associated with AD-related weight loss, and decrease in fat mass may have a key role.

Early functional network alterations in asymptomatic elders at risk for Alzheimer's disease

Amyloid-β (Aβ) deposition is known to starts decades before the onset of clinical symptoms of Alzheimer's disease (AD), however, the detailed pathophysiological processes underlying this preclinical period are not well understood. This study aimed to investigate functional network alterations in cognitively intact elderly individuals at risk for AD, and assessed the association between these network alterations and changes in Aβ deposition, glucose metabolism, and brain structure. Forty-five cognitively normal elderly subjects, who were classified into Aβ-positive (CN+) and Aβ-negative (CN-) groups using ¹¹C-Pittsburgh compound B PET, underwent resting state magnetoencephalography measurements, ¹⁸F-fluorodeoxyglucose PET (FDG-PET) and structural MRI. Results demonstrated that in the CN+ group, functional connectivity (FC) within the precuneus was significantly decreased, whereas it was significantly enhanced between the precuneus and the bilateral inferior parietal lobules in the low-frequency bands (theta and delta). These changes were suggested to be associated with local cerebral Aβ deposition. Most of Aβ+ individuals in this study did not show any metabolic or anatomical changes, and there were no significant correlations between FC values and FDG-PET or MRI volumetry data. These results demonstrate that functional network alterations, which occur in association with Aβ deposition, are detectable using magnetoencephalography before metabolic and anatomical changes are seen.

Neuropsychological differentiation between Alzheimer's disease and dementia with Lewy bodies in a memory clinic

OBJECTIVE

The aim of this study was to identify a useful neuropsychological instrument for making a differential clinical diagnosis between Alzheimer's disease (AD) and dementia with Lewy bodies (DLB).

METHODS

We examined 402 AD and 38 DLB patients with neuropsychological tests that covered general cognition, frontal lobe cognitive function, non-verbal abstract reasoning, working memory and attention, and verbal memory. Discriminant analysis using a stepwise method was performed to identify the measures best able to discriminate between AD and DLB.

RESULTS

The AD patients performed significantly worse than the DLB patients on orientation to time, delayed recall subtests on the Mini-Mental State Examination, and logical memory subtests 1 and 2 of the Revised Wechsler Memory Scale. The DLB patients performed significantly worse than the AD patients on the attention, repetition, and pentagon copying subtests of the Mini-Mental State Examination, the constructional praxis subtests of the Alzheimer's Disease Assessment Scale-cognitive component-Japanese version, the Frontal Assessment Battery total score, Raven's Coloured Progressive Matrices (RCPM) sets A, AB, and B, and backward digit span. Discriminant analyses between AD and DLB established the key variables as Logical Memory 1, Logical Memory 2, backward digit span, RCPM, and delayed recall on the Mini-Mental State Examination. We inferred the AD-DLB discriminant index from the following discriminant analyses: AD-DLB discriminant index = (Backward digit span score + RCPM set B score) - (Logical Memory 1 score + Logical Memory 2 score), which offered a highly favourable value for diagnostic utility.

CONCLUSIONS

The AD-DLB discriminant index, consisting of backward digit span, RCPM set B, and logical memory 1 and 2, is useful to differentiate between AD and DLB.

Direct comparison study between FDG-PET and IMP-SPECT for diagnosing Alzheimer's disease using 3D-SSP analysis in the same patients

PURPOSE

The purpose of this study was to evaluate and compare the diagnostic ability of 2-[(18)F]-fluoro-2-deoxy-D: -glucose (FDG) positron emission tomography (PET) and N-isopropyl-p-(123)I iodoamphetamine single photon emission computed tomography (IMP-SPECT) using three-dimensional stereotactic surface projections (3D-SSP) in patients with moderate Alzheimer's disease (AD).

MATERIALS AND METHODS

FDG-PET and IMP-SPECT were performed within 3 months in 14 patients with probable moderate AD. Z-score maps of FDG-PET and IMP-SPECT images of a patient were obtained by comparison with data obtained from control subjects. Four expert physicians evaluated and graded the glucose hypometabolism and regional cerebral blood flow (rCBF), focusing in particular on the posterior cingulate gyri/precunei and parietotemporal regions, and determined the reliability for AD. Receiver operating characteristic (ROC) curves were applied to the results for clarification. To evaluate the correlation between two modalities, the regions of interest (ROIs) were set in the posterior cingulate gyri/precunei and parietotemporal region on 3D-SSP images, and mean Z-values were calculated.

CONCLUSION

No significant difference was observed in the area under the ROC curve (AUC) between FDG-PET and IMP-SPECT images (FDG-PET 0.95, IMP-SPECT 0.94). However, a significant difference (P < 0.05) was observed in the AUC for the posterior cingulate gyri/precuneus (FDG-PET 0.94, IMP-SPECT 0.81). The sensitivity and specificity of each modality were 86%, and 97% for FDG-PET and 70% and 100% for IMP-SPECT. We could find no significant difference between FDG-PET and IMP-SPECT in terms of diagnosing moderate AD using 3D-SSP. There was a high correlation between the two modalities in the parietotemporal region (Spearman's r = 0.82, P < 0.001). The correlation in the posterior cingulate gyri/precunei region was lower than that in the parietotemporal region (Spearman's r = 0.63, P < 0.016).

[Molecular imaging in Parkinson's disease]

Molecular imaging techniques using PET or SPECT have provided major insights into not only objective diagnosis of Parkinson's disease(PD), but also understanding the pathophysiological process in the disease progression. At disease onset, a compensatory hyperactivity of dopa decarboxylase in the nigrostriatal and extrastriatal dopaminergic pathways and upregulation of postsynaptic D2 receptor have been demonstrated. In the advanced stage, an excessively earlier release of dopamine from the residual neurons has been shown, suggesting a relationship with motor complications. In terms of therapy of PD, functional images have provided some objective evidences for possible neuroprotective effect of dopamine agonists, survival of fetal dopaminergic tissue grafted into patient's putamen, an increase of dopamine release by BDNF focal infusion therapy, and functional modification by deep brain stimulation. In vivo imaging of gene expression under developing may be informative in the future gene therapy in PD.

Cerebral atrophy and its relation to cognitive impairment in Parkinson disease

OBJECTIVE

Voxel-based morphometry was used to compare the amounts of gray matter in the brains of patients with Parkinson disease (PD) and normal control subjects (NCs) and to identify the specific regions responsible for cognitive dysfunction in PD.

METHODS

Patients were classified into nondemented (ND) and demented (D) groups according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders (4th ed.), and a group comparison was performed. In the ND patients, a correlation was also performed between local gray matter density and the score on Raven Colored Progressive Matrices (RCPM), a test of executive and visuospatial function.

RESULTS

In patients with advanced ND-PD vs NCs, atrophic changes were observed in the limbic/paralimbic areas and the prefrontal cortex. In D vs ND patients, atrophic change was observed widely in the limbic/paralimbic system, including the anterior cingulate gyrus and hippocampus as well as the temporal lobe, dorsolateral prefrontal cortex, thalamus, and caudate nucleus. The RCPM score was positively correlated with the gray matter density in the dorsolateral prefrontal cortex and the parahippocampal gyrus.

CONCLUSIONS

In patients with Parkinson disease (PD), atrophic changes occur mainly in the limbic/paralimbic and prefrontal areas. These atrophic changes may be related to the development of dementia in PD.

Cognitive- and motor-related regions in Parkinson's disease: FDOPA and FDG PET studies

OBJECTIVE

Using 6-[(18)F]fluoro-L-dopa (FDOPA) and [(18)F]fluorodeoxyglucoce (FDG) positron emission tomography (PET), multiple regression analyses were performed to determine the specific brain regions that are related to cognitive and motor symptoms in nondemented patients with Parkinson's disease.

METHODS

Spatially normalized images of FDOPA influx rate constant (Ki) values and relative regional cerebral metabolic rates for glucose (rrCMRglc) were created. Raven's Coloured Progressive Matrices (RCPM) scores and the Unified Parkinson's Disease Rating Scale (UPDRS) motor scores were used to determine the patients' cognitive and motor functions, respectively. Multiple correlation analyses between the FDOPA and FDG images and the cognitive and motor scores were performed for each voxel.

RESULTS

RCPM score was significantly positively correlated with the FDOPA Ki in the left hippocampus and with the rrCMRglc in the left middle frontal gyrus and right retrosplenial cortex. Motor function was significantly positively correlated with the FDOPA Ki in the bilateral striatum and with the rrCMRglc in association areas and primary visual cortex. The level of motor function was significantly inversely correlated with the FDOPA Ki in the anterior cingulate gyrus and with the rrCMRglc in bilateral primary motor cortex and right putamen.

CONCLUSIONS

Changes of striatal FDOPA uptake and rrCMRglc in the primary motor cortex likely represent dysfunction in the motor system involving the corticobasal ganglia-thalamocortical loop. Change of FDOPA uptake in the anterior cingulate gyrus may be related to up-regulation of dopamine synthesis in surviving dopamine neurons. The regions where correlation with cognitive function was observed belong to a cognitive frontoparietal-hippocampal network.

Visual hallucination in Parkinson's disease with FDG PET

To determine the characteristics of cerebral glucose metabolism in Parkinson's disease patients with visual hallucinations, group comparison studies using [18F]fluorodeoxyglucose positron emission tomography were performed. Nondemented Parkinson's disease patients in advanced stages were classified into two groups: (1) patients without visual hallucinations; (2) patients with visual hallucinations. Compared to patients without hallucinations, the relative regional cerebral glucose metabolic rate was greater in the frontal areas in patients with visual hallucinations, and the increase reached a significant level in the left superior frontal gyrus. Relative frontal hypermetabolism may be a feature of Parkinson's disease patients with visual hallucinations.

Neuroradiologic and clinical abnormalities in dementia of diffuse neurofibrillary tangles with calcification (Kosaka-Shibayama disease)

We describe a characteristic dementia patient diagnosed as diffuse neurofibrillary tangles with calcification (DNTC). Neuropsychologically, dementia, including a decline in memory retention and intelligence, and anomic aphasia were recognized. Imaging revealed circumscribed temporal dominant atrophy and calcification of the basal ganglia and cerebellum. SPECT and FDG-PET revealed a remarkable reduction of blood flow and metabolism in the temporal lobes; however, there is no reduction in the basal ganglia and cerebellum, and FDOPA-PET also disclosed no abnormalities. This suggests that calcification and neuronal degeneration occur independently in DNTC.

Occipital hypoperfusion in Parkinson's disease without dementia: correlation to impaired cortical visual processing

OBJECTIVE

The purpose of this study was to analyse changes in regional cerebral blood flow (rCBF) in Parkinson's disease (PD) without dementia.

METHODS

Twenty eight non-demented patients with PD and 17 age matched normal subjects underwent single photon emission computed tomography with N-isopropyl-p-[(123)I]iodoamphetamine to measure rCBF. The statistical parametric mapping 96 programme was used for statistical analysis.

RESULTS

The PD patients showed significantly reduced rCBF in the bilateral occipital and posterior parietal cortices (p<0.01, corrected for multiple comparison p<0.05), when compared with the control subjects. There was a strong positive correlation between the score of Raven's coloured progressive matrices (RCPM) and the rCBF in the right visual association area (p<0.01, corrected for multiple comparison p<0.05) among the PD patients.

CONCLUSIONS

This study showed occipital and posterior parietal hypoperfusion in PD patients without dementia. Furthermore, it was demonstrated that occipital hypoperfusion is likely to underlie impairment of visual cognition according to the RCPM test, which is not related to motor impairment.

Discrimination between Alzheimer dementia and controls by automated analysis of multicenter FDG PET

A new diagnostic indicator of FDG PET scan abnormality, based on age-adjusted t statistics and an automated voxel-based procedure, is presented and validated in a large data set comprising 110 normal controls and 395 patients with probable Alzheimer's disease (AD) that were studied in eight participating centers. The effect of differences in spatial resolution of PET scanners was minimized effectively by filtering and masking. In controls FDG uptake declined significantly with age in anterior cingulate and frontolateral perisylvian cortex. In patients with probable AD decline of FDG uptake in posterior cingulate, temporoparietal, and prefrontal association cortex was related to dementia severity. These effects were clearly distinct from age effects in controls, suggesting that the disease process of AD is not related to normal aging. Women with probable AD had significantly more frontal metabolic impairment than men. The new indicator of metabolic abnormality in AD-related regions provided 93% sensitivity and specificity for distinction of mild to moderate probable AD from normals, and 84% sensitivity at 93% specificity for detection of very mild probable AD (defined by Mini Mental Score 24 or better). All regions related to AD severity were already affected in very mild AD, suggesting that all vulnerable areas are affected to a similar degree already at disease onset. Ventromedial frontal cortex was also abnormal. In conclusion, automated analysis of multicenter FDG PET is feasible, provides insights into AD pathophysiology, and can be used potentially as a sensitive biomarker for early AD diagnosis.

Striatal and extrastriatal dysfunction in Parkinson's disease with dementia: a 6-[18F]fluoro-L-dopa PET study

We investigated the relative differences in dopaminergic function through the whole brain in patients with Parkinson's disease without dementia (PD) and with dementia (PDD) using 6-[18F]fluoro-L-dopa (18F-dopa) PET and a voxel-by-voxel analysis. The 10 PD and 10 PDD patients were equivalently disabled, having mean scores of 3.2 +/- 0.6 and 3.2 +/- 0.7, respectively, on the Hoehn and Yahr rating scale. 18F-dopa influx constant (Ki) images of those patients and 15 normal age-matched subjects were transformed into standard stereotactic space. The significant differences between the groups (expressed in mean regional Ki values) were localized with statistical parametric mapping (SPM) on a voxel-by-voxel basis. Compared with the normal group, SPM localized declines of the 18F-dopa Ki bilaterally in the putamen, the right caudate nucleus and the left ventral midbrain for the PD group (P < 0.01, corrected). Compared with the normal group, the PDD group showed reduced 18F-dopa Ki bilaterally in the striatum, midbrain and anterior cingulate area (P < 0.01, corrected). A relative difference in 18F-dopa uptake between PD and PDD was the bilateral decline in the anterior cingulate area and ventral striatum and in the right caudate nucleus in the PDD group (P < 0.001, corrected). Accordingly, we conclude that dementia in PD is associated with impaired mesolimbic and caudate dopaminergic function.

[Effects of tandospirone citrate on frozen gait in patients with early stage of progressive supranuclear palsy, investigated by walk-induced activation single photon emission computed tomography method]

We reported a 64-year-old woman in the early stage of progressive supranuclear palsy presenting as pure akinesia syndrome who showed marked improvement with tandospirone citrate. She revealed bradykinesia, severe frozen gait and disturbance of postural reflex without rigidity or tremor. Treatment with L-dopa and L-threo DOPS was not effective, but tandospirone citrate at a daily dosage of 30 mg significantly lessened the severity of frozen gait. Activation single photon emission computed tomography study with 99mTc-ethyl cysteinate dimer during gait revealed a significant increase in brain activity in the right cingulate cortex after tandospirone citrate treatment. The effect lasted ten months until neck rigidity and ventricular supranuclear palsy were evident.

Extrastriatal mean regional uptake of fluorine-18-FDOPA in the normal aged brain--an approach using MRI-aided spatial normalization

The aim of this study was to define the mean regional 6-[(18)F]fluoro-l-dopa (FDOPA) uptake rate constant (K(i)) values in the striatal and extrastriatal regions of the brain of normal subjects using magnetic resonance imaging (MRI)-aided spatial normalization of the FDOPA K(i) image and using automatic region of interest (ROI) analysis. Dynamic three-dimensional FDOPA positron emission tomography (PET) and three-dimensional magnetic resonance (MR) images were acquired in 13 aged normal subjects. The FDOPA add image and the K(i) image of each subject were transformed into standard stereotactic space with the aid of individual coregistered MR image. The mean regional K(i) values of the striatal and extrastriatal regions before normalization were compared with the respective values after normalization. Then automatic ROI analysis was performed on the MRI-aided spatially normalized K(i) images of the 13 normal subjects. The K(i) values on original images and those on spatially normalized images were in good agreement, indicating that the spatial normalization technique did not change the regional K(i) values appreciably. Automatic ROI analysis of the spatially normalized FDOPA K(i) images of the normal subjects, showed high K(i) values in ventral and dorsal regions of the midbrain, amygdala, hippocampus, and medial prefrontal cortex, in addition to caudate nucleus and putamen, which correspond to the dopaminergic projections in the brain. Spatial normalization technique helped to establish a database of FDOPA K(i) images of normal subjects and high K(i) values were observed widely besides striatal regions corresponding to the dopaminergic projections in the brain.

[An adult patient of Reye's syndrome--the possible background mechanism of lesions in claustrum, striatum and limbic system and limbic dementia]

We reported a 35-year-old male patient with Reye's syndrome, who showed temporarily lesions of claustrum, striatum, hippocampus and amygdala on CT, MRI and PET scan. He was previously healthy and affected upper respiratory infection. After taking 4 tablets of aspirin (335 mg x 4), he developed severe headache and status epileptics. The cerebrospinal fluid showed normal cell count and protein. The serum GOT and GPT elevated to 499 IU/l and 221 IU/l respectively. The parainfluenza virus type I titer was 32 times on admission and increased up to 128 times two weeks later. In spite of the anticonvulsant, status epileptics lasted for about one month and he needed mechanical ventilation. On 13-18 days of illness, abnormal lesions appeared in bilateral claustrum and striatum on CT and MRI. On 49 days of illness, abnormal lesions appeared in bilateral hippocampus and amygdala. All these lesions changed into normal on MRI on 111 days of illness. The 18F-FDG PET study on 80 days of illness revealed high uptake on striatum, hippocampus and amygdala bilaterally and changed into normal on 130 days of illness. He has improved markedly but showed long-standing abnormal signs of limbic dementia. We suggested this patient could be suffered from post infectious encephalitis in limbic system after Reye's syndrome.

Parieto-occipital glucose hypometabolism in Parkinson's disease with autonomic failure

To investigate the characteristics of regional cerebral metabolism in a subgroup of patients with Parkinson's disease and autonomic failure, we studied seven patients with Parkinson's disease with autonomic failure (PA group), 11 patients with Parkinson's disease without apparent autonomic failure (PD group), and nine normal controls using fluoro-deoxyglucose positron emission tomography (FDG-PET). To determine differences in metabolic distribution among these groups, regional relative glucose metabolic rates (RGMR), which were normalized with cerebellar values, were calculated and age-adjusted covariance analyses were done. When compared with that of controls. RGMR in the cerebral cortex of the PA group was markedly reduced in the occipital cortex (P<0.001), inferior parietal cortex (P<0.005) and superior parietal cortex (P<0.005), but without a decrease in the sensory motor and medial temporal cortices, putamen and thalamus. In contrast, the PD group did not show significant focal hypometabolic distribution. Our findings raise the possibility that Parkinson's disease with autonomic failure may overlap with the features of dementia with Lewy bodies.

Cisplatin neurotoxicity presenting as reversible posterior leukoencephalopathy syndrome

Visual disturbance, hypertension, convulsions, and unconsciousness developed in a 70-year-old man after cisplatin chemotherapy and upper-limb amputation for osteosarcoma. MR imaging revealed bilateral reversible abnormalities in the occipital, parietal, and frontal white matter. Clinical and neuroradiologic features corresponded to reversible posterior leukoencephalopathy syndrome (RPLS), which some immunosuppressive and chemotherapeutic drugs have been reported to trigger. Cisplatin may be among these drugs. Our patient also had hypomagnesemia, which may have figured in the pathophysiology.

[18F-fluorodeoxyglucose positron emission tomography in Parkinson's disease]

Positron emission topographic studies on local cerebral glucose metabolism in Parkinson's disease (PD) including our own data were reviewed. In our 18F-FDG PET studies, local or global metabolic change was not found in 9 patients with non-demented PD, with respect to 5 normal controls. Moreover, there was not an apparent difference between severe PD group (Hoehn-Yahr III-IV) and mild PD group (Hoehn-Yahr I-II). In other PD patients with dementia or autonomic failure, parietal dominant hypometabolism was found likely to those of Alzheimer disease, but lenticular nucleus was well preserved. Furthermore 18F-FDG PET findings of atypical parkinsonian syndromes, such as SND and PSP were reviewed. They showed relative hypometabolism in the basal ganglia in PET images. PET study with FDG provides a clue to differential diagnosis of parkinsonian patients.

[MRI findings in patients with vertigo and dizziness possibly arising from vertebrobasilar insufficiency]

In order to evaluate diagnostic usefulness of MRI in vertebrobasilar insufficiency (VBI), we performed magnetic resonance imaging (MRI) and MR angiography (MRA) in 90 patients presenting vertigo and dizziness as an initial and cardinal complaint. High signals observed by T2-weighted imaging in the basal ganglia (44.4%) or pontine base (48.9%) were more frequently seen in the possible VBI group than in the controls (p < 0.001). The electronystagmographical abnormalities were commonly observed in the patients with a high signal in the pontine base, reflecting diffuse ischemic lesion in the territory of the vertebrobasilar system. Vertebral artery asymmetry (45.6%) or basilar artery twisting (41.1%) as shown by MRA was also significantly more frequent in the patients than in the controls (p < 0.05). In conclusion, MRI and MRA were considered to be useful in making a clinical diagnosis of VBI in such patients.

[Clinical significance of pontine high signals identified on magnetic resonance imaging]

Spin-echo magnetic resonance imaging (MRI) was evaluated to 530 cases in order to investigate the clinical, significance of pontine high signals. The subjects comprised 109 cases of pontine infarction with high signal on T2-weighted image and low signal on T1-weighted image (PI group), 145 of pontine high signal with high signal on T2-weighted image but normal signal on T1-weighted image (PH group) and 276 of age-matched control without abnormality either on T1 or T2-weighted images (AC group). Subjective complaints such as vertigo-dizziness were more frequent in the PH group than in the PI group. In both PI and PH groups, periventricular hyperintensity as well as subcortical high signals in the supratentorium were more severe than in the AC group. These degrees were higher in the PI group than in the PH group. In conclusion, PH as well as PI may result from diffuse arteriosclerosis and PH is considered to be an early finding of pontine ischemia.