Differentiation of dementia with Lewy bodies from Alzheimer's disease using brain SPECT

Utility of combining multiple parameters of 123I-IMP SPECT and voxel-based morphometry MRI using a multiparametric scoring system for differentiating dementia with Lewy bodies from Alzheimer's disease

BACKGROUND

Brain magnetic resonance imaging voxel-based morphometry (VBM) and perfusion single-photon emission computed tomography (SPECT) are useful for differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD).

PURPOSE

To determine whether combining multiple parameters of VBM and SPECT using a multiparametric scoring system (MSS) improves diagnostic accuracy in differentiating DLB from AD.

MATERIAL AND METHODS

In total, 23 patients with DLB and 57 patients with AD underwent imaging using a voxel-based specific regional analysis system for AD (VSRAD), an easy Z-score imaging system, and a Z-Graph using three-dimensional stereotactic surface projection. The cutoff values were determined using the receiver operating characteristic curve to differentiate DLB from AD for all parameters. Patients were scored 1 (DLB) or 0 (AD) for each statistically significant parameter, according to a threshold. The total score was determined for each case to obtain a cutoff value for the MSS.

RESULTS

The mean Z-scores in the medial temporal lobes using the VSRAD were significantly lower in patients with DLB than in those with AD. Each Z-score of the summed Z-scores in all four segmented regions of the occipital lobes using the Z-Graph was significantly higher in patients with DLB than in those with AD. Among the five parameters, the highest accuracy was 80% for the Z-score of the summed Z-scores in the left medial occipital lobe. For the MSS, a cutoff value of four improved the diagnostic accuracy to 82%.

CONCLUSION

MSS was more accurate than any single parameter of VBM or SPECT in differentiating DLB from AD.

Brain perfusion SPECT in dementia: what radiologists should know

The findings of brain perfusion single-photon emission computed tomography (SPECT), which detects abnormalities often before changes manifest in morphological imaging, mainly reflect neurodegeneration and contribute to dementia evaluation. A major shift is about to occur in dementia practice to the approach of diagnosing based on biomarkers and treating with disease-modifying drugs. Accordingly, brain perfusion SPECT will be required to serve as a biomarker of neurodegeneration. Hypoperfusion in Alzheimer's disease (AD) is typically seen in the posterior cingulate cortex and precuneus early in the disease, followed by the temporoparietal cortices. On the other hand, atypical presentations of AD such as the posterior variant, logopenic variant, frontal variant, and corticobasal syndrome exhibit hypoperfusion in areas related to symptoms. Additionally, hypoperfusion especially in the precuneus and parietal association cortex can serve as a predictor of progression from mild cognitive impairment to AD. In dementia with Lewy bodies (DLB), the differentiating feature is the presence of hypoperfusion in the occipital lobes in addition to that observed in AD. Hypoperfusion of the occipital lobe is not a remarkable finding, as it is assumed to reflect functional loss due to impairment of the cholinergic and dopaminergic systems rather than degeneration per se. Moreover, the cingulate island sign reflects the degree of AD pathology comorbid in DLB. Frontotemporal dementia is characterized by regional hypoperfusion according to the three clinical types, and the background pathology is diverse. Idiopathic normal pressure hydrocephalus shows apparent hypoperfusion around the Sylvian fissure and corpus callosum and apparent hyperperfusion in high-convexity areas. The cortex or striatum with diffusion restriction on magnetic resonance imaging in prion diseases reflects spongiform degeneration and brain perfusion SPECT reveals hypoperfusion in the same areas. Brain perfusion SPECT findings in dementia should be carefully interpreted considering background pathology.

EEG-based clinical decision support system for Alzheimer's disorders diagnosis using EMD and deep learning techniques

Introduction

Despite the existence of numerous clinical techniques for identifying neurological brain disorders in their early stages, Electroencephalogram (EEG) data shows great promise as a means of detecting Alzheimer's disease (AD) at an early stage. The main goal of this research is to create a reliable and accurate clinical decision support system leveraging EEG signal processing to detect AD in its initial phases.

Methods

The research utilized a dataset consisting of 35 neurotypical individuals, 31 patients with mild AD, and 22 patients with moderate AD. Data were collected while participants were at rest. To extract features from the EEG signals, a band-pass filter was applied to the dataset and the Empirical Mode Decomposition (EMD) technique was employed to decompose the filtered signals. The EMD technique was then leveraged to generate feature vectors by combining multiple signal features, thereby enhancing diagnostic performance. Various artificial intelligence approaches were also explored and compared to identify features of the extracted EEG signals distinguishing mild AD, moderate AD, and neurotypical cases. The performance of the classifiers was evaluated using k-fold cross-validation and leave-one-subject-out (LOSO) cross-validation methods.

Results

The results of this study provided valuable insights into potential avenues for the early diagnosis of AD. The performance of the various offered methodologies has been compared and evaluated by computing the overall diagnosis precision, recall, and accuracy. The proposed methodologies achieved a maximum classification accuracy of 99.9 and 94.8% for k-fold and LOSO cross-validation techniques, respectively.

Conclusion

The study aims to assess and compare different proposed methodologies and determine the most effective combination approach for the early detection of AD. Our research findings strongly suggest that the proposed diagnostic support technique is a highly promising supplementary tool for discovering prospective diagnostic biomarkers that can greatly aid in the early clinical diagnosis of AD.

Altered cerebral blood flow in older adults with Alzheimer's disease: a systematic review

The prevalence of Alzheimer's disease is projected to reach 13 million in the U.S. by 2050. Although major efforts have been made to avoid this outcome, so far there are no treatments that can stop or reverse the progressive cognitive decline that defines Alzheimer's disease. The utilization of preventative treatment before significant cognitive decline has occurred may ultimately be the solution, necessitating a reliable biomarker of preclinical/prodromal disease stages to determine which older adults are most at risk. Quantitative cerebral blood flow is a promising potential early biomarker for Alzheimer's disease, but the spatiotemporal patterns of altered cerebral blood flow in Alzheimer's disease are not fully understood. The current systematic review compiles the findings of 81 original studies that compared resting gray matter cerebral blood flow in older adults with mild cognitive impairment or Alzheimer's disease and that of cognitively normal older adults and/or assessed the relationship between cerebral blood flow and objective cognitive function. Individuals with Alzheimer's disease had relatively decreased cerebral blood flow in all brain regions investigated, especially the temporoparietal and posterior cingulate, while individuals with mild cognitive impairment had consistent results of decreased cerebral blood flow in the posterior cingulate but more mixed results in other regions, especially the frontal lobe. Most papers reported a positive correlation between regional cerebral blood flow and cognitive function. This review highlights the need for more studies assessing cerebral blood flow changes both spatially and temporally over the course of Alzheimer's disease, as well as the importance of including potential confounding factors in these analyses.

The Legacy of the TTASAAN Report-Premature Conclusions and Forgotten Promises: A Review of Policy and Practice Part I

Brain perfusion single photon emission computed tomography (SPECT) scans were initially developed in 1970's. A key radiopharmaceutical, hexamethylpropyleneamine oxime (HMPAO), was originally approved in 1988, but was unstable. As a result, the quality of SPECT images varied greatly based on technique until 1993, when a method of stabilizing HMPAO was developed. In addition, most SPECT perfusion studies pre-1996 were performed on single-head gamma cameras. In 1996, the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology (TTASAAN) issued a report regarding the use of SPECT in the evaluation of neurological disorders. Although the TTASAAN report was published in January 1996, it was approved for publication in October 1994. Consequently, the reported brain SPECT studies relied upon to derive the conclusions of the TTASAAN report largely pre-date the introduction of stabilized HMPAO. While only 12% of the studies on traumatic brain injury (TBI) in the TTASAAN report utilized stable tracers and multi-head cameras, 69 subsequent studies with more than 23,000 subjects describe the utility of perfusion SPECT scans in the evaluation of TBI. Similarly, dementia SPECT imaging has improved. Modern SPECT utilizing multi-headed gamma cameras and quantitative analysis has a sensitivity of 86% and a specificity of 89% for the diagnosis of mild to moderate Alzheimer's disease-comparable to fluorodeoxyglucose positron emission tomography. Advances also have occurred in seizure neuroimaging. Lastly, developments in SPECT imaging of neurotoxicity and neuropsychiatric disorders have been striking. At the 25-year anniversary of the publication of the TTASAAN report, it is time to re-examine the utility of perfusion SPECT brain imaging. Herein, we review studies cited by the TTASAAN report vs. current brain SPECT imaging research literature for the major indications addressed in the report, as well as for emerging indications. In Part II, we elaborate technical aspects of SPECT neuroimaging and discuss scan interpretation for the clinician.

The Feasibility of Differentiating Lewy Body Dementia and Alzheimer's Disease by Deep Learning Using ECD SPECT Images

The correct differential diagnosis of dementia has an important impact on patient treatment and follow-up care strategies. Tc-99m-ECD SPECT imaging, which is low cost and accessible in general clinics, is used to identify the two common types of dementia, Alzheimer's disease (AD) and Lewy body dementia (LBD). Two-stage transfer learning technology and reducing model complexity based on the ResNet-50 model were performed using the ImageNet data set and ADNI database. To improve training accuracy, the three-dimensional image was reorganized into three sets of two-dimensional images for data augmentation and ensemble learning, then the performance of various deep learning models for Tc-99m-ECD SPECT images to distinguish AD/normal cognition (NC), LBD/NC, and AD/LBD were investigated. In the AD/NC, LBD/NC, and AD/LBD tasks, the AUC values were around 0.94, 0.95, and 0.74, regardless of training models, with an accuracy of 90%, 87%, and 71%, and F1 scores of 89%, 86%, and 76% in the best cases. The use of transfer learning and a modified model resulted in better prediction results, increasing the accuracy by 32% for AD/NC. The proposed method is practical and could rapidly utilize a deep learning model to automatically extract image features based on a small number of SPECT brain perfusion images in general clinics to objectively distinguish AD and LBD.

[Accuracy of Classification of Cerebral Blood Flow Reduction Patterns Using Statistical Analysis Images Generated with Simulated SPECT Datasets via Deep Learning]

PURPOSE

The aim of this study was to evaluate the classification accuracy of specific blood flow reduction patterns in clinical images by deep learning using simulation data.

METHODS

We obtained Z-score maps for 100 cases each of simulated Alzheimer's disease (AD), simulated dementia with Lewy bodies (DLB), and simulated normal cognition (NC) by performing statistical analysis of the simulation data that provided defects and healthy patient data. The clinical images were determined by reference to radiological reports, and Z-score maps of AD (n=33), DLB (n=20), and NC (n=28) were used. A network was constructed with reference to AlexNet, 4-fold cross-validation was performed using only simulation data, and classification accuracy was evaluated. We also trained the model using the simulation data and classified the clinical images.

RESULTS

The accuracy rate of classification between simulations was 96.2% and that of the clinical images was 84.2%.

CONCLUSION

Through deep learning using simulation data, clinical images may be classified with an accuracy of 84.2%.

Brain SPECT as a Biomarker of Neurodegeneration in Dementia in the Era of Molecular Imaging: Still a Valid Option?

Biomarkers are playing a progressively leading role in both clinical practice and scientific research in dementia. Although amyloid and tau biomarkers have gained ground in the clinical community in recent years, neurodegeneration biomarkers continue to play a key role due to their ability to identify different patterns of brain involvement that sign the transition between asymptomatic and symptomatic stages of the disease with high sensitivity and specificity. Both ¹⁸F-FDG positron emission tomography (PET) and perfusion single photon emission computed tomography (SPECT) have proved useful to reveal the functional alterations underlying various neurodegenerative diseases. Although the focus of nuclear neuroimaging has shifted to PET, the lower cost and wider availability of SPECT make it a still valid alternative for the study of patients with dementia. This review discusses the principles of both techniques, compares their diagnostic performance for the diagnosis of neurodegenerative diseases and highlights the role of SPECT to characterize patients from low- and middle-income countries, where special care of additional costs is particularly needed to meet the new recommendations for the diagnosis and characterization of patients with dementia.

Molecular mechanisms in Alzheimer's disease and the impact of physical exercise with advancements in therapeutic approaches

Alzheimer's disease (AD) is one of the most common, severe neurodegenerative brain disorder characterized by the accumulation of amyloid-beta plaques, neurofibrillary tangles in the brain causing neural disintegration, synaptic dysfunction, and neuronal death leading to dementia. Although many US-FDA-approved drugs like Donepezil, Rivastigmine, Galantamine are available in the market, their consumption reduces only the symptoms of the disease but fails in potency to cure the disease. This disease affects many individuals with aging. Combating the disease tends to be very expensive. This review focuses on biochemical mechanisms in the neuron both at normal and AD state with relevance to the tau hypothesis, amyloid hypothesis, the risk factors influencing dementia, oxidative stress, and neuroinflammation altogether integrated with neurodegeneration. A brief survey is carried out on available biomarkers in the diagnosis of the disease, drugs used for the treatment, and the challenges in approaching therapeutic targets in inhibiting the disease pathologies. This review conjointly assesses the demerits with the inefficiency of drugs to reach targets, their side effects, and toxicity. Optimistically, this review directs on the advantageous strategies in using nanotechnology-based drug delivery systems to cross the blood-brain barrier for improving the efficacy of drugs combined with a novel neuronal stem cell therapy approach. Determinately, this review aims at the natural, non-therapeutic healing impact of physical exercise on different model organisms and the effect of safe neuromodulation treatments using repetitive Transcranial Magnetic Stimulation (rTMS), transcranial Electrical Stimulation (tES) in humans to control the disease pathologies prominent in enhancing the synaptic function.

Application of Artificial Neural Networks to Identify Alzheimer's Disease Using Cerebral Perfusion SPECT Data

The aim of this study was to demonstrate the usefulness of artificial neural networks in Alzheimer disease diagnosis (AD) using data of brain single photon emission computed tomography (SPECT). The results were compared with discriminant analysis. The study population consisted of 132 clinically diagnosed patients. There were 72 subjects with AD and 60 belonging to the normal control group. The artificial neural network used 36 numerical values being the count numbers obtained for each area of brain SPECT. These numbers determined the set of input data for the artificial neural network. The sensitivity of Alzheimer disease diagnosis detection by artificial neural network and discriminant analysis were 93.8% and 86.1%, respectively, and the corresponding specificity was 100% and 95%. We also used receiver operating characteristic curve (ROC) analysis and areas under receiver operating characteristics curves were correspondingly 0.97 (p < 0.0001) for the artificial neural networks (ANN) and 0.96 (p < 0.0001) for discriminant analysis. In conclusion, artificial neural networks and conventional statistics methods (discriminant analysis) are a useful tool in Alzheimer disease diagnosis.

Molecular Imaging of Dementia With Lewy Bodies

Dementia with Lewy bodies (DLB) is the second most common cause of neurodegenerative dementia. The core clinical features of DLB include fluctuating cognition, visual hallucinations, rapid eye movement sleep behavior disorder, and parkinsonism. Molecular imaging is a powerful tool to assess the brain function in vivo. In this chapter, we reviewed the positron emission tomography, single-photon emission computed tomography, and [¹²³I]-metaiodobenzylguanidine scintigraphy studies evaluating the pathological processes underlying DLB, including altered brain metabolism and neurotransmitter pathways, abnormal protein aggregation, and neuroinflammation. These techniques can aid in the differential diagnosis of DLB (versus Alzheimer's disease and related dementia) and in the monitoring disease progression and treatment efficacy of disease-modifying drugs. Furthermore, we explored the limitations of current imaging biomarkers and future directions, particularly focusing on the vital need for tracers that have high affinity for alpha-synuclein.

Neuroimaging in Lewy body dementia

Lewy body dementia (DLB) is a common form of cognitive impairment, accounting for 30% of dementia cases in ages over 65 years. Early diagnosis of DLB has been challenging; particularly in the context of differentiation with Parkinson’s disease dementia and other forms of dementias, such as Alzheimer’s disease and rapidly progressive dementias. Current practice involves the use of [¹²³I]FP-CIT-SPECT, [¹⁸F]FDG PET and [¹²³I]MIBG molecular imaging to support diagnostic procedures. Structural imaging techniques have an essential role for excluding structural causes, which could lead to a DLB-like phenotype, as well as aiding differential diagnosis through illustrating disease-specific patterns of atrophy. Novel PET molecular imaging modalities, such as amyloid and tau imaging, may provide further insights into DLB pathophysiology and may aid in early diagnosis. A multimodal approach, through combining various established techniques and possibly using novel radioligands, might further aid towards an in-depth understanding of this highly disabling disease. In this review, we will provide an overview of neuroimaging applications in patients with DLB.

Occipital lobe and posterior cingulate perfusion in the prediction of dementia with Lewy body pathology in a clinical sample

OBJECTIVE

The aim of this study was to investigate the diagnostic value of occipital lobe and posterior cingulate perfusion in predicting dopamine transporter imaging outcome using a quantitative measure of analysis.

PATIENTS AND METHODS

In total, 99 patients with cognitive complaints who had undergone both technetium-99m-hexamethylpropyleneamine oxime single-photon emission computed tomography (Tc-HMPAO SPECT) and I ioflupane (I-FP-CIT also called DaTSCAN) imaging in a dementia diagnostic center were analyzed. Measures of perfusion were calculated from HMPAO SPECT images for the medial and lateral occipital lobe, the posterior cingulate cortex, precuneus and cuneus regions of interest using statistical parametric mapping 8. DaTSCAN images were quantified and specific binding ratios were calculated independent from HMPAO SPECT results. Statistical parametric mapping and tests of associations between perfusion and I-FP-CIT imaging were completed.

RESULTS

Regions of interest on HMPAO yielded poor predictive values when used independently to predict I-FP-CIT status; however, the combination of normal posterior cingulate perfusion with medial and lateral occipital hypoperfusion was associated significantly with I-FP-CIT status, χ (1, N=99)=9.72, P=0.002. This combination also yielded a high positive likelihood ratio and specificity (11.1, 98%). Sensitivity was, however, low (22%). No significant perfusion differences were found when abnormal and normal I-FP-CIT groups were compared directly using voxel-based morphometry (P<0.05, family-wise error).

CONCLUSION

The combination of medial and lateral occipital hypoperfusion with preserved posterior cingulate gyrus perfusion is highly specific for individuals with a positive I-FP-CIT scan in a clinical sample where diagnostic doubt exists. This regional combination, however, lacks sensitivity; therefore, absence of the sign cannot be used to rule out dementia with Lewy bodies. A positive finding provides strong evidence to rule in dementia with Lewy bodies.

Different Clinical and Neuroimaging Characteristics in Early Stage Parkinson's Disease with Dementia and Dementia with Lewy Bodies

Parkinson’s disease with dementia (PDD) and dementia with Lewy bodies (DLB) both commonly exhibit brain Lewy body pathology and similar end-stage symptoms, but early symptoms differ. To clarify these differences, we compared the demographic characteristics, symptoms, cognitive and affective functioning, activities of daily life, and neuroimaging results between PDD (n = 52) and DLB (n = 46) patients. In measures of cognitive functioning, PDD patients had worse Hasegawa dementia scale-revised (HDS-R) scores (11.2±4.8) and better frontal assessment battery (FAB) scores (11.3±4.1) compared with DLB (17.0±6.4, p = 0.013 and 8.6±4.7, p = 0.039, respectively). DLB patients performed worse than PDD patients in “orientation to place” tasks. In affective functions, DLB patients had worse GDS (7.6±3.4) and ABS (9.9±5.3) scores than PDD patients (5.1±4.1 and 4.8±3.0, respectively). ^99mTc-ECD images showed greater CBF in the whole cingulate gyrus and a lower CBF in the precuneus area in DLB than in PDD. These results suggest that PDD patients’ lower average scores for “repetition” (MMSE), “recent memory” (HDS-R), and “lexical fluency” (FAB) were related to lower CBF in the cingulate gyrus than in DLB. Furthermore, DLB patients’ poorer average subscale scores of “orientation to place” (MMSE) and “similarities”, “conflicting instructions”, and “go-no go” (FAB) tasks may be related to the lower CBF in the precuneus area in DLB than PDD.

Imaging in Dementia With Lewy Bodies: An Overview

Dementia with Lewy bodies (DLB) while common in older age can present a diagnostic challenge to clinicians and is often misdiagnosed as Alzheimer disease (AD). Imaging studies have improved our understanding of the neurobiological changes in DLB during life and how they differ from AD. This has led to significant advances in the development of new techniques, such as dopaminergic imaging, which can aid the clinical diagnosis. Other functional imaging methods also show promise in helping to assess the influence of differing pathologies in DLB, most notably, AD-related and vascular pathology during life. This article will provide an overview of the main imaging findings in DLB.

Multimodal EEG-MRI in the differential diagnosis of Alzheimer's disease and dementia with Lewy bodies

Differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) remains challenging; currently the best discriminator is striatal dopaminergic imaging. However this modality fails to identify 15-20% of DLB cases and thus other biomarkers may be useful. It is recognised electroencephalography (EEG) slowing and relative medial temporal lobe preservation are supportive features of DLB, although individually they lack diagnostic accuracy. Therefore, we investigated whether combined EEG and MRI indices could assist in the differential diagnosis of AD and DLB. Seventy two participants (21 Controls, 30 AD, 21 DLB) underwent resting EEG and 3 T MR imaging. Six EEG classifiers previously generated using support vector machine algorithms were applied to the present dataset. MRI index was derived from medial temporal atrophy (MTA) ratings. Logistic regression analysis identified EEG predictors of AD and DLB. A combined EEG-MRI model was then generated to examine whether there was an improvement in classification compared to individual modalities. For EEG, two classifiers predicted AD and DLB (model: χ(2) = 22.1, df = 2, p < 0.001, Nagelkerke R(2) = 0.47, classification = 77% (AD 87%, DLB 62%)). For MRI, MTA also predicted AD and DLB (model: χ(2) = 6.5, df = 1, p = 0.01, Nagelkerke R(2) = 0.16, classification = 67% (77% AD, 52% DLB). However, a combined EEG-MRI model showed greater prediction in AD and DLB (model: χ(2) = 31.1, df = 3, p < 0.001, Nagelkerke R(2) = 0.62, classification = 90% (93% AD, 86% DLB)). While suggestive and requiring validation, diagnostic performance could be improved by combining EEG and MRI, and may represent an alternative to dopaminergic imaging.

Analysis of primary visual cortex in dementia with Lewy bodies indicates GABAergic involvement associated with recurrent complex visual hallucinations

Dementia with Lewy bodies (DLB) patients frequently experience well formed recurrent complex visual hallucinations (RCVH). This is associated with reduced blood flow or hypometabolism on imaging of the primary visual cortex. To understand these associations in DLB we used pathological and biochemical analysis of the primary visual cortex to identify changes that could underpin RCVH. Alpha-synuclein or neurofibrillary tangle pathology in primary visual cortex was essentially absent. Neurone density or volume within the primary visual cortex in DLB was also unchanged using unbiased stereology. Microarray analysis, however, demonstrated changes in neuropeptide gene expression and other markers, indicating altered GABAergic neuronal function. Calcium binding protein and GAD65/67 immunohistochemistry showed preserved interneurone populations indicating possible interneurone dysfunction. This was demonstrated by loss of post synaptic GABA receptor markers including gephyrin, GABARAP, and Kif5A, indicating reduced GABAergic synaptic activity. Glutamatergic neuronal signalling was also altered with vesicular glutamate transporter protein and PSD-95 expression being reduced. Changes to the primary visual cortex in DLB indicate that reduced GABAergic transmission may contribute to RCVH in DLB and treatment using targeted GABAergic modulation or similar approaches using glutamatergic modification may be beneficial.

Single-photon emission tomography

Single-photon emission computed tomography (SPECT) is a functional nuclear imaging technique that allows visualization and quantification of different in vivo physiologic and pathologic features of brain neurobiology. It has been used for many years in diagnosis of several neurologic and psychiatric disorders. In this chapter, we discuss the current state-of-the-art of SPECT imaging of brain perfusion and dopamine transporter (DAT) imaging. Brain perfusion SPECT imaging plays an important role in the localization of the seizure onset zone in patients with refractory epilepsy. In cerebrovascular disease, it can be useful in determining the cerebrovascular reserve. After traumatic brain injury, SPECT has shown perfusion abnormalities despite normal morphology. In the context of organ donation, the diagnosis of brain death can be made with high accuracy. In neurodegeneration, while amyloid or (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) are the nuclear diagnostic tools of preference for early and differential diagnosis of dementia, perfusion SPECT imaging can be useful, albeit with slightly lower accuracy. SPECT imaging of the dopamine transporter system is widely available in Europe and Asia, but since recently also in the USA, and has been accepted as an important diagnostic tool in the early and differential diagnosis of parkinsonism in patients with unclear clinical features. The combination of perfusion SPECT (or FDG-PET) and DAT imaging provides differential diagnosis between idiopathic Parkinson's disease, Parkinson-plus syndromes, dementia with Lewy bodies, and essential tremor.

Comparison of (123)I-MIBG myocardial scintigraphy, brain perfusion SPECT, and voxel-based MRI morphometry for distinguishing between dementia with Lewy bodies and Alzheimer's disease

OBJECTIVE

This study aimed to compare the diagnostic value of (123)I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, N-isopropyl-p[(123)I]iodoamphetamine (IMP) brain perfusion single-photon emission computed tomography (SPECT), and brain magnetic resonance imaging (MRI) voxel-based morphometry (VBM) for the differentiation of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD).

METHODS

Thirty-five and 34 patients with probable DLB and probable AD, respectively, were enrolled. All patients underwent (123)I-MIBG myocardial scintigraphy, (123)I-IMP brain perfusion SPECT, and brain MRI. For (123)I-MIBG imaging, we calculated early and delayed heart-to-mediastinum (H/M) uptake ratios. Three-dimensional stereotactic surface projections (3D-SSP) were used to analyze the results of (123)I-IMP SPECT. VBM with statistical parametric mapping 8 plus diffeomorphic anatomical registration using exponentiated Lie algebra (DARTEL) was used to analyze the brain MRI data.

RESULTS

The area under the receiver operating characteristic curves (AUC) for discriminating DLB and AD was highest (0.882) for the delayed H/M ratio on (123)I-MIBG scintigraphy. AUC for z-score measurement in the occipital lobe was 0.818 and that for the extent of gray matter (GM) atrophy in the whole brain was 0.788. AUC for the combination of 3D-SSP and VBM analysis was 0.836. The respective sensitivities and specificities for distinguishing DLB from AD were 97.1 and 100 % for the delayed H/M ratio using (123)I-MIBG scintigraphy; 88.6 and 73.5 % for the occipital lobe z-score using 3D-SSP analysis; 85.7 and 64.7 % for the extent of whole brain GM atrophy using voxel-based MRI morphometry; and 91.4 and 76.5 % for the combination of 3D-SSP analysis and VBM.

CONCLUSIONS

(123)I-MIBG myocardial scintigraphy was superior to brain perfusion SPECT and brain MRI using an advanced statistical technique to differentiate DLB and AD.

A comparison of FDG-PET and blood flow SPECT in the diagnosis of neurodegenerative dementias: a systematic review

OBJECTIVE

Perfusion single photon emission computed tomography (SPECT) and 18F fluorodeoxyglucose positron emission tomography (FDG-PET) both have clinical utility for the differential diagnosis of dementia. Although PET is often viewed by some as more accurate and therefore preferential, the extent to which published evidence supports this is not clear. The aim of this review was to address the question by reviewing studies of SPECT and PET imaging in dementia diagnosis, with a particular focus on all published head-to-head studies.

DESIGN

A MEDLINE search was carried out using the following keywords: "PET" and "SPECT" and "dementia" or "Mild Cognitive Impairment," together with "alzheimers" or "DLB" or "lewy body" or "frontotemporal" or "FTD" or "Picks." Articles were included up to February 2013, limited to human studies and in English language.

RESULTS

Published studies of SPECT accuracy show that it is a useful tool for differential diagnosis, with sensitivities of 65-85% for diagnosing Alzheimer's disease (AD) and specificities (for other neurodegenerative dementias) of 72-87%. PET studies generally report higher accuracy, with sensitivities of 75-99% for AD and specificities of 71-93%. However, there have been few direct head-to-head comparisons, with some indicating SPECT and PET to be equally useful in dementia diagnosis and others favouring PET. Many of these studies are limited with respect to numbers and methodically with poorly matched control groups.

CONCLUSIONS

Overall, although studies suggest superiority of PET over SPECT, the evidence base for this is actually quite limited. We suggest that further direct comparative studies, including health economic and patient preference evaluations, are needed to help direct future service provision.

Clinical utility of SPECT neuroimaging in the diagnosis and treatment of traumatic brain injury: a systematic review

Purpose

This systematic review evaluated the clinical utility of single photon emission computed tomography (SPECT) in traumatic brain injury (TBI).

Methods

After defining a PICO Statement (Population, Intervention, Comparison and Outcome Statement), PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria were applied to identify 1600 articles. After screening, 374 articles were eligible for review. Inclusion for review was focus on SPECT in the setting of mild, moderate, or severe TBI with cerebral lobar specificity of SPECT findings. Other inclusion criteria were comparison modalities in the same subjects and articles in English. Foreign language articles, SPECT studies that did not include comparison modalities, and case reports were not included for review.

Results

We identified 19 longitudinal and 52 cross-sectional studies meeting inclusion criteria. Three longitudinal studies examined diagnostic predictive value. The first showed positive predictive value increases from initial SPECT scan shortly after trauma to one year follow up scans, from 59% to 95%. Subsequent work replicated these results in a larger cohort. Longitudinal and cross sectional studies demonstrated SPECT lesion localization not detected by CT or MRI. The most commonly abnormal regions revealed by SPECT in cross-sectional studies were frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in both acute and chronic imaging of TBI, particularly mild TBI. It was also found to have a near 100% negative predictive value.

Conclusions

This review demonstrates Level IIA evidence (at least one non-randomized controlled trial) for the value of SPECT in TBI. Given its advantages over CT and MRI in the detection of mild TBI in numerous studies of adequate quality, and given its excellent negative predictive value, it may be an important second test in settings where CT or MRI are negative after a closed head injury with post-injury neurological or psychiatric symptoms.

Multivariate spatial covariance analysis of 99mTc-exametazime SPECT images in dementia with Lewy bodies and Alzheimer's disease: utility in differential diagnosis

We examined (99m)Tc-exametazime brain blood flow single-photon emission computed tomography (SPECT) images using a spatial covariance analysis (SCA) approach to assess its diagnostic value in distinguishing dementia with Lewy bodies (DLB) from Alzheimer's disease (AD). Voxel SCA was simultaneously applied to a set of preprocessed images (AD, n=40; DLB, n=26), generating a series of eigenimages representing common intercorrelated voxels in AD and DLB. Linear regression derived a spatial covariance pattern (SCP) that discriminated DLB from AD. To investigate the diagnostic value of the model SCP, the SCP was validated by applying it to a second, independent, AD and DLB cohort (AD, n=34; DLB, n=29). Mean SCP expressions differed between AD and DLB (F(1,64)=36.2, P<0.001) with good diagnostic accuracy (receiver operating characteristic (ROC) curve area 0.87, sensitivity 81%, specificity 88%). Forward application of the model SCP to the independent cohort revealed similar differences between groups (F(1,61)=38.4, P<0.001), also with good diagnostic accuracy (ROC 0.86, sensitivity 80%, specificity 80%). Multivariate analysis of blood flow SPECT data appears to be robust and shows good diagnostic accuracy in two independent cohorts for distinguishing DLB from AD.

The diagnosis and evaluation of dementia and mild cognitive impairment with emphasis on SPECT perfusion neuroimaging

As the world population ages, the incidence of dementing illnesses will dramatically increase. The number of people afflicted with dementia is expected to quadruple in the next 50 years. Since the neuropathology of the dementias precedes clinical symptoms often by several years, earlier detection and intervention could be key steps to mitigating the progression and burden of these diseases. This review will explore methods of evaluating, differentiating, and diagnosing the multiple forms of dementia. Particular emphasis will be placed on the diagnosis of mild cognitive impairment-the precursor to dementia. Anatomical imaging; cerebrospinal fluid markers; functional neuroimaging, such as positron emission tomography and single photon emission tomography; and molecular imaging, such as amyloid marker imaging, will be assessed in terms of sensitivity and specificity. Cost will also be a consideration, as the growing population afflicted with dementia represents an increasingly large financial encumbrance to the healthcare systems of every nation. In the face of expensive new markers and limited availability of cyclotrons, single photon emission computer tomography (SPECT) provides relatively high sensitivity and specificity at a comparatively low overall cost.

Neuroimaging of dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a relative newcomer to the field of late-life dementia. Although a diversity of imaging methodologies is now available for the study of dementia, these have been applied most often to Alzheimer's disease (AD). Studies on DLB, although fewer, have yielded fascinating and important insights into the underlying pathophysiology of this condition and allowed clinical differentiation of DLB from other dementias. Imaging research on DLB has had significant ramifications in terms of raising the profile of DLB and helping define it as a distinctive and separate disease entity from AD.

Biomarkers in dementia with Lewy bodies: a review

BACKGROUND

Dementia with Lewy bodies (DLB) shares common clinical, neuropsychological and pathological features with other dementia subtypes, such as Alzheimer's disease (AD), making it difficult to differentiate in clinical practice. Despite the development of consensus diagnostic criteria, many cases are missed, and biomarkers to assist with diagnosis would represent important advances. Our aim was to review the literature to identify potential biomarkers that may distinguish DLB from other dementia subtypes, especially AD.

METHOD

The literature search was performed using Medline up to October 2010 for imaging studies [single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI) and amyloid imaging] and cerebrospinal fluid (CSF) markers in DLB. Individual articles were examined for additional references. The abstracts of the identified articles were read to determine the most relevant papers, which became the basis for this review.

RESULTS

The most robust evidence available was for striatal dopamine transporter activity visualised by (123) I-labelled N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl)nortropane ((123) I-FP-CIT) SPECT. Several other imaging techniques have also reported promising results, such as [(18) F]fluorodopa PET, which assesses nigrostriatal integrity; [(18) F]fluorodeoxyglucose PET, which assesses metabolic deficits; and meta-iodobenzylguanidine imaging, which assesses sympathetic cardiac denervation. Data from studies using CSF measures of amyloid and tau, occipital hypoperfusion on SPECT and preservation of medial temporal lobe structures on MRI suggest that they may offer less diagnostic discrimination.

CONCLUSION

Several potential biomarkers have shown good diagnostic accuracy for DLB, but apart from FP-CIT SPECT, there is now a need for larger clinical multi-site studies, as well as for studies with pathological verification of diagnosis, before their use could be recommended for routine clinical practice.

Functional MRI evidence for distinctive binding and consolidation pathways for face-name associations: analysis of activation maps and BOLD response amplitudes

OBJECTIVE

Although some of the anatomical underpinnings of learning and memory systems have been identified, there remains little understanding of how the brain moves from acquiring new information to retaining it. This study was designed to further explore and elucidate the neural mechanisms underlying encoding and memory in a common real-life task, that is, face-name associations. One possible outcome is that the tasks will recruit different neural structures mediating these processes, which can be identified through contrast analysis of activations. Alternatively, it is possible that similar anatomical regions, such as the hippocampus and parahippocampal gyrus, may be involved in both tasks. In that case, analysis of blood oxygenation level dependent (BOLD) amplitude differences between the tasks in those common neural structures may be able to detect whether physiological activation differences occur in encoding versus memory.

METHODS

Five healthy adult participants underwent high-field magnetic resonance imaging (MRI) while learning face-name pairs (encoding phase) and during a multiple-choice recognition task after a brief delay (memory phase). Average activation and BOLD response amplitudes in specific regions of interest and whole-brain activation maps were analyzed.

RESULTS

Common activations were observed in the encoding and recognition memory tasks in several regions of interest encompassing the medial temporal and inferior occipital regions. However, higher BOLD response amplitudes occurred in the right fusiform gyrus and the right hippocampus during encoding. In contrast, higher amplitudes were detected in the lingual gyrus bilaterally during recognition memory. Encoding activated distributed prefrontal and temporal cortical regions bilaterally, which mediate attentional, executive, language, and memory systems. Recognition memory recruited a different network of regions encompassing convergence zones in the left prefrontal cortex and the parietal-occipital-temporal region bilaterally, where multimodal visual association, language, memory, and decision-making systems interact.

CONCLUSIONS

Higher BOLD response amplitudes in the right fusiform gyrus and the right hippocampus during face-name encoding suggest a potentially specific binding pathway where disparate information might be neurally linked. In contrast, the increased BOLD response in the lingual gyrus during recognition memory may indicate a key neural substrate for memory consolidation and long-term knowledge of what is learned. Whole-brain activation maps revealed task-specific differences in areas of the prefrontal, temporal, and occipital-parietal-temporal junctions as well. Findings suggest that there are distinctive anatomical and physiological nodes for face-name learning and memory within large-scale cortical-subcortical networks. Hence, lesions in fairly widespread cerebral regions may potentially disrupt specific binding and/or memory consolidation processes.

Perfusion Imaging with SPECT in the Era of Pathophysiology-Based Biomarkers for Alzheimer's Disease

SPECT allows registration of regional cerebral blood flow (rCBF) which is altered in a characteristic temporoparietal pattern in Alzheimer's Dementia. Numerous studies have shown the diagnostic value of reduced cerebral blood flow and metabolic changes using perfusion SPECT and FDG-PEPT in AD diagnosis as well as in differential diagnosis against frontotemporal dementia, dementia with Lewy bodies and vascular disease. Recently more pathophysiology-based biomarkers in CSF and Amyloid-PET tracers have been developed that probably have a higher diagnostic accuracy than the more indirect rCBF changes seen in perfusion SPECT. In the paper review, we describe recent advances in AD biomarkers as well as improvements in the SPECT technique.

Cerebrospinal fluid biomarkers for dementia with lewy bodies

More than 750,000 of the UK population suffer from some form of cognitive impairment and dementia. Of these, 5–20% will have Dementia with Lewy Bodies (DLB). Clinico-pathological studies have shown that it is the low frequency of DLB clinical core features that makes the DLB diagnosis hardly recognisable during life, and easily misdiagnosed for other forms of dementia. This has an impact on the treatment and long-term care of the affected subjects. Having a biochemical test, based on quantification of a specific DLB biomarker within Cerebrospinal Fluid (CSF) could be an effective diagnostic method to improve the differential diagnosis. Although some of the investigated DLB CSF biomarkers are well within the clinical criteria for sensitivity and specificity (>90%), they all seem to be confounded by the contradictory data for each of the major groups of biomarkers (α-synuclein, tau and amyloid proteins). However, a combination of CSF measures appear to emerge, that may well be able to differentiate DLB from other dementias: α-synuclein reduction in early DLB, a correlation between CSF α-synuclein and Aβ42 measures (characteristic for DLB only), and t-tau and p-tau181 profile (differentiating AD from DLB).

Covariance 99mTc-exametazime SPECT patterns in Alzheimer's disease and dementia with Lewy bodies: utility in differential diagnosis

(99m)Tc-exametazime single photon emission computed tomography (SPECT) scans of 36 patients with Alzheimer's disease (AD) and 30 with dementia with Lewy bodies (DLB) underwent region of interest (ROI) and principal component analysis (PCA). Principal component analysis was performed on the entire ROI data set. Principal components (PCs) were obtained, representing common intercorrelated regions in AD and DLB. Topographic expression that signified the extent to which a participant expressed the topographic covariance pattern was derived and used as a discriminatory variable. Principal components were identified, accounting for 77% of total data variance. Significant (PC x group) interaction was observed (P < .001). Topographic expression was significantly higher in DLB than AD (F(1,64) = 21.6, P < .001), and differentiated DLB from AD with sensitivity 73% specificity 72%. Calculating the topographic expression in an independent data set of 48 patients with AD and 23 with DLB gave sensitivity = 70%, specificity = 67%. Principal component analysis captures additional sources of variance and if perfusion SPECT is the only scan available, this procedure may offer extra information.

Differential diagnosis of dementia with Lewy Bodies and Alzheimer Disease using combined MR imaging and brain perfusion single-photon emission tomography

BACKGROUND AND PURPOSE

Diagnostic performance by MR imaging or by SPECT alone in discriminating DLB patients from AD patients has been estimated previously. However, the performance of a combination of MR imaging and SPECT has not yet been evaluated. Our aim was to evaluate the usefulness of combining MR imaging and SPECT to discriminate mild DLB from AD.

MATERIALS AND METHODS

Nineteen patients with mild DLB and 19 age- and cognitive decline-matched patients with mild AD underwent both SPECT and MR imaging. Hippocampal, occipital, and striatal volume and SPECT count ratios were compared. Linear discriminant and ROC analyses were performed by using the parameters of striatal volume and the occipital SPECT ratio.

RESULTS

The striatal volume ratio in the DLB group was significantly lower than that in the AD group. The occipital SPECT ratio in the DLB group was lower than that in the AD group. The mean area under the ROC curve from combined MR imaging and SPECT (AUC = 0.898) was higher than that from MR imaging (AUC = 0.679) or SPECT (AUC = 0.798) alone.

CONCLUSIONS

By combining MR imaging and SPECT, we were able to distinguish patients with mild DLB from those with AD with a high level of accuracy. Our findings suggest that combining MR imaging and SPECT modalities is a useful and practical approach for diagnostically differentiating DLB from AD.

A comparison of 99mTc-exametazime and 123I-FP-CIT SPECT imaging in the differential diagnosis of Alzheimer's disease and dementia with Lewy bodies

BACKGROUND

The aim of this study is to investigate the diagnostic value of perfusion 99mTc-exametazime single photon emission computed tomography (SPECT) in the diagnosis of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) in comparison with dopaminergic 123I-2beta-carbomethoxy-3beta-(4-iodophenyl)-n-(3-fluoropropyl) nortropane (FP-CIT) SPECT imaging.

METHODS

Subjects underwent 99mTc-exametazime scanning (39 controls, 36 AD, 30 DLB) and 123I-FP-CIT scanning (33 controls, 33 AD, 28 DLB). For each scan, five raters performed visual assessments blind to clinical diagnosis on selected transverse 99mTc-exametazime images in standard stereotactic space. Diagnostic accuracy of 99mTc-exametazime was compared to 123I-FP-CIT results for the clinically relevant subgroups AD and DLB using receiver operating characteristic (ROC) curve analysis.

RESULTS

Inter-rater agreement for categorizing uptake was "moderate" (mean kappa = 0.53) for 99mTc-exametazime and "excellent" (mean kappa = 0.88) for 123I-FP-CIT. For AD and DLB, consensus rating matched clinical diagnosis in 56% of cases using 99mTc-exametazime and 84% using 123I-FP-CIT. In distinguishing AD from DLB, ROC analysis revealed superior diagnostic accuracy with 123I-FP-CIT (ROC curve area 0.83, sensitivity 78.6%, specificity 87.9%) compared to occipital 99mTc-exametazime (ROC curve area 0.64, sensitivity 64.3%, specificity 63.6%) p = 0.03.

CONCLUSION

Diagnostic accuracy was superior with 123I-FP-CIT compared to 99mTc-exametazime in the differentiation of DLB from AD.

Early discriminatory diagnosis of dementia with Lewy bodies. The emerging role of CSF and imaging biomarkers

BACKGROUND

The clinical diagnostic criteria for dementia with Lewy bodies (DLB) have a low sensitivity, and there are no generally accepted biomarkers to distinguish DLB from other dementias. Our aim was to identify biomarkers that may differentiate DLB from Alzheimer's disease (AD).

METHOD

We performed a systematic literature search for studies of EEG, imaging techniques and genetic and CSF markers that provide sensitivity and specificity in the identification of DLB.

RESULTS

The best evidence was for scintigraphy of the striatal dopamine transporter system using FP-CIT SPECT. Several small scintigraphy studies of cardiovascular autonomic function using metaiodobenzylguanidine SPECT have reported promising results. Studies exploring innovative techniques based on CSF have reported interesting findings for the combination of amyloid beta (abeta) isoforms as well as alpha-synuclein, and there are interesting results emerging from preliminary studies applying proteomic techniques. Data from studies using structural MRI, perfusion SPECT, genetics and EEG studies show differences between DLB and AD but only at a group level.

CONCLUSION

Several potential biomarkers for the differential diagnosis of probable DLB and AD have shown good diagnostic accuracy in the research setting. Data from large multicentre studies and from studies with autopsy confirmation exist for scintigraphy of the dopamine transporter system. Future studies should explore its value in possible DLB and for clinical management and health economics.

Dementia with Lewy bodies

The advent of new immunostains have improved the ability to detect limbic and cortical Lewy bodies, and it is evident that dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia, after Alzheimer's disease (AD). Distinguishing DLB from AD has important implications for treatment, in terms of substances that may worsen symptoms and those that may improve them. Neurocognitive patterns, psychiatric features, extrapyramidal signs, and sleep disturbance are helpful in differentiating DLB from AD early in the disease course. Differences in the severity of cholinergic depletion and type/distribution of neuropathology contribute to these clinical differences.

Démence à corps de Lewy et démence associée à la maladie de Parkinson

Lewy body dementia and Parkinson disease dementia are frequent causes of degenerative dementia: 20% of the dementias in patients older than 65 years are caused by the former and nearly 80% of patients with advanced Parkinson disease develop the latter. Symptoms of Lewy body dementia include fluctuations of cognitive performance, frontal and visuospatial impairment, visual hallucinations, and parkinsonism. Parkinson disease dementia could be differentiated in two subtypes: a "subcortical" subtype, characterized by frontal impairment with apathy and dullness and a "cortical" subtype with symptoms similar to those of Lewy body dementia. Mastery of potential iatrogenic factors is important: psychotropic drugs must be prescribed at the strict minimum, and L-dopa monotherapy at the minimal dose acceptable for correcting Parkinsonian motor symptoms should be the rule. Acetylcholinesterase inhibitors may be useful in both these types of dementia: rivastigmine is approved for treating Parkinson disease dementia and clozapine for reducing hallucinations.

Evaluation of brain perfusion SPECT using an easy Z-score imaging system (eZIS) as an adjunct to early-diagnosis of neurodegenerative diseases

The eZIS allows computer-assisted statistical analysis of brain perfusion SPECT images. We evaluated the diagnostic value of brain perfusion SPECT using eZIS in patients with various neurodegenerative diseases at a very early stage, within one year from onset.

METHODS

SPECT using eZIS was performed for patients with Alzheimer disease (AD), dementia with Lewy bodies (DLB), frontotemporal dementia (FTD,), idiopathic Parkinson disease (PD) and vascular Parkinsonism (VP), multiple systemic atrophy of the cerebellar type (MSA-C), cortical cerebellar atrophy (CCA) and amyotrophic lateral sclerosis (ALS).

RESULTS

Decreased rCBF was observed in the posterior cingulate cortex, precuneus and parietal cortex in AD; in the frontal gyrus and insula in FTD; in the occipital lobe, precuneus gyrus and posterior cingulate cortex in DLB; in the striatum and the thalamus in VP; in the cerebellum in CCA; in the cerebellum and pons in MSA-C and in the frontal cortex including the central sulcus in ALS. Increased rCBF in the striatum, thalamus and cerebellar dentate nuclei were observed in PD.

CONCLUSIONS

A specific rCBF pattern was observed for each disease using eZIS analysis, consistent with previous reports. Our results showed eZIS can be easily used as an adjunct to early-diagnosis of neurodegenerative diseases in any hospital.

Treatment of dementia in parkinsonian syndromes with cholinesterase inhibitors

In Parkinsonian syndromes behavioural symptoms and dementia can be even more debilitating than motor symptoms and are an important predictor for nursing home placement and mortality. Neuropathologically, dementia seems to be primarily related to cortical changes rather than to subcortical alterations. Concerning neurotransmitter systems, the cholinergic system has been proposed to play a key role in cognitive disturbances. Based on studies with patients with Alzheimer disease, the application of cholinesterase inhibitors is vividly discussed also for dementia associated with parkinsonian syndromes. This review focuses on the specific symptoms of dementia in different parkinsonian syndromes and critically questions the effect of cholinergic treatment on cognitive functions in patients with extrapyramidal syndromes and dementia. There is evidence that medication with some cholinesterase inhibitors can enhance cognition as well as activities of daily living in dementia with Parkinson's disease and seems to reduce behavioural disturbances in both dementia with Parkinson's disease and dementia with Lewy bodies. The effect of treatment with cholinesterase inhibitors in progressive supranuclear palsy and corticobasal degeneration warrants carefully designed studies including a sufficient number of patients and symptom-adopted dementia scales.

Limitations of the HMPAO SPECT appearances of occipital lobe perfusion in the differential diagnosis of dementia with Lewy bodies

OBJECTIVE

To assess the utility of the appearances of occipital lobe perfusion on HMPAO SPECT in the diagnosis of dementia with Lewy bodies (DLB) using the 123I-FP-CIT findings as the diagnostic 'gold standard'.

METHODS

Eighty-four consecutive patients underwent both HMPAO SPECT and 123I-FP-CIT as part of their routine investigations for suspected DLB.

RESULTS

Thirty-nine of the 84 FP-CIT scans were abnormal indicating a prevalence of 44% of patients with DLB in this series. In those patients classified as DLB, 28% of HMPAO SPECT scans demonstrated occipital hypoperfusion. In those patients with a dementia other than DLB 31% of patients demonstrated occipital hypoperfusion (P=0.8).

CONCLUSION

Occipital lobe hypoperfusion as demonstrated by HMPAO SPECT in patients with suspected Lewy body dementia does not appear to be able to either rule in, or rule out, the diagnosis of DLB.

Imaging in dementia with Lewy bodies: a review

This review discusses the role of functional and structural imaging in patients with suspected dementia with Lewy bodies, with particular emphasis on SPECT and PET dopaminergic and cerebral perfusion/metabolic techniques. It is envisaged that this information may be useful to nuclear medicine physicians, radiologists, psychiatrists, neurologists, geriatricians and physicians.

Cortical Lewy body disease and Parkinson's disease dementia

PURPOSE OF REVIEW

The health and socioeconomic impacts of dementia with Lewy bodies and dementia associated with Parkinson's disease have become increasingly recognized. Whilst the nosological status of dementia with Lewy bodies has been better classified as 'Lewy body dementias', both conditions are now believed to represent a disease spectrum, characterized pathologically by synuclein protein and clinically by a variable admixture of cognitive, neuropsychiatric and extrapyramidal features.

RECENT FINDINGS

Recent epidemiological studies are described and clinical and pathological similarities emphasized between dementia with Lewy bodies and Parkinson's disease. A number of investigational techniques are highlighted which have helped to better characterize dementia with Lewy bodies and discriminate it from Alzheimer's disease, whilst also shedding light upon the pathophysiology of both conditions. Finally, the therapeutic aspects of the Lewy body dementias will be considered, concentrating upon studies of the cholinesterase inhibitors.

SUMMARY

The pathology underlying dementia with Lewy bodies and Parkinson's disease is heterogeneous, and is neither stereotyped in its topography nor its composition. Cholinesterase inhibitor drugs improve cognition and neuropsychiatric symptoms but the clinical response is unpredictable. Major future challenges are to better understand the pathophysiological basis underpinning the diseases, what determines clinical phenotypic expression and how disease-modifying therapies may best be developed and deployed.

Differentiation of dementia with Lewy bodies from Alzheimer's disease using Mini-Mental State Examination and brain perfusion SPECT

To determine whether combined studies of Mini-Mental State Examination (MMSE) and brain single photon emission CT (SPECT) would provide more useful means of differentiating between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD), we studied 36 patients with probable DLB and 96 patients with probable AD. DLB patients had significantly better performance on word recall, but more impaired attention and copying than AD patients. We confirmed that a weighted score derived by Ala et al. [Ala, T.A., Hughes, L.F., Kyrouac, G.A., Ghobrial, M.W., Elble, R.J. The Mini-Mental State exam may help in the differentiation of dementia with Lewy bodies and Alzheimer' disease. Int J Geriatr Psychiatry 2002;17:503-9]: (Attention-5/3.Memory+5.Construction), was helpful in discriminating between DLB and AD. SPECT study revealed that medial occipital perfusion significantly decreased in DLB patients than AD patients. Combined studies of MMSE and brain SPECT achieved a high discrimination between DLB and AD with a sensitivity of 81% and a specificity of 85%, suggesting that there is a useful and practical approach to differentiate DLB from AD. Our findings will need to be substantiated in an independent and prospective study sample.

Demencia con cuerpos de Lewy y enfermedad de Alzheimer: diagnóstico diferencial mediante estudio de la inervación simpática cardíaca con MIBG

Dementia with Lewy bodies (DLB) is the second most common cause of degenerative dementia after Alzheimer's disease (AD). At present, pre-mortem diagnosis of DLB can only be made clinically using the International Consensus Criteria. However, an accurate differential diagnosis between these diseases could improve the therapeutic handling of patients with DLB, due to their supersensitivity to neuroleptic treatment and the difficult treatment of their psychotic symptoms.

OBJECTIVE

To assess the utility of cardiac MIBG imaging as diagnostic study for DLB, to help in the differential diagnosis with AD.

MATERIAL AND METHODS

Cardiac MIBG imaging was performed in 11 patients with clinical criteria of probable DLB (7 males, mean age 77 years [range 62-89 years], mean MMSE 17 [range 11-28], and in 9 patients with clinical criteria of probable AD (3 males, mean age 79 years [range 61-87 years], mean MMSE 17 [range 4-25]). Planar anterior images of the thorax were acquired at 15 minutes. (early study) and 4 hours (late study) after tracer injection. Myocardial MIBG activity was quantified by means of a heart-to-mediastinum ratio (HMR). A HMR > 1.8 was considered normal.

RESULTS

Respect AD patients, patients with DLB showed decreased HMR in the early study (1.34 +/- 0.27 [range 1.03-1.98] vs. 1.84 +/- 0.22 [range 1.53-2.15], p<0.001) and in the late study (1.22 +/- 0.23 [range 0.95-1.75] vs. 1.73 +/- 0.08 [range 1.59-1.89], p<0.0001).

CONCLUSIONS

Cardiac MIBG imaging could be a useful tool for differential diagnosis between DLB and AD.

Comparative value of brain perfusion SPECT and [(123)I]MIBG myocardial scintigraphy in distinguishing between dementia with Lewy bodies and Alzheimer's disease

PURPOSE

Both decreased occipital perfusion on brain single-photon emission computed tomography (SPECT) and reduction in cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake are characteristic features of dementia with Lewy bodies (DLB), and potentially support the clinical diagnosis of DLB. The aim of this study was to compare the diagnostic value of these two methods for differentiation of DLB from Alzheimer's disease (AD).

METHODS

The study population comprised 19 patients with probable DLB and 39 patients with probable AD who underwent both SPECT with N-isopropyl-p-[(123)I]iodoamphetamine and MIBG myocardial scintigraphy. Objective and quantitative measurement of perfusion in the medial occipital lobe, including the cuneus and lingual gyrus, was performed by the use of three-dimensional stereotactic surface projections.

RESULTS

Medial occipital perfusion was significantly decreased in the DLB group compared with the AD group. The mean heart/mediastinum ratios of MIBG uptake were significantly lower in the DLB group than in the AD group. Although SPECT failed to demonstrate significant hypoperfusion in the medial occipital lobe in five patients with DLB, marked reduction of MIBG uptake was found in all patients with DLB. Receiver operating characteristic analysis revealed that MIBG myocardial scintigraphy enabled more accurate discrimination between DLB and AD than was possible with perfusion SPECT.

CONCLUSION

MIBG myocardial scintigraphy may improve the sensitivity in the detection of DLB. In particular, this method may provide a powerful differential diagnostic tool when it is difficult to distinguish cases of DLB from AD using brain perfusion SPECT.