123I-MIBG myocardial scintigraphy for the diagnosis of DLB: a multicentre 3-year follow-up study

Differentiating Prodromal Dementia with Lewy Bodies from Prodromal Alzheimer's Disease: A Pragmatic Review for Clinicians

This pragmatic review synthesises the current understanding of prodromal dementia with Lewy bodies (pDLB) and prodromal Alzheimer's disease (pAD), including clinical presentations, neuropsychological profiles, neuropsychiatric symptoms, biomarkers, and indications for disease management. The core clinical features of dementia with Lewy bodies (DLB)-parkinsonism, complex visual hallucinations, cognitive fluctuations, and REM sleep behaviour disorder are common prodromal symptoms. Supportive clinical features of pDLB include severe neuroleptic sensitivity, as well as autonomic and neuropsychiatric symptoms. The neuropsychological profile in mild cognitive impairment attributable to Lewy body pathology (MCI-LB) tends to include impairment in visuospatial skills and executive functioning, distinguishing it from MCI due to AD, which typically presents with impairment in memory. pDLB may present with cognitive impairment, psychiatric symptoms, and/or recurrent episodes of delirium, indicating that it is not necessarily synonymous with MCI-LB. Imaging, fluid and other biomarkers may play a crucial role in differentiating pDLB from pAD. The current MCI-LB criteria recognise low dopamine transporter uptake using positron emission tomography or single photon emission computed tomography (SPECT), loss of REM atonia on polysomnography, and sympathetic cardiac denervation using meta-iodobenzylguanidine SPECT as indicative biomarkers with slowing of dominant frequency on EEG among others as supportive biomarkers. This review also highlights the emergence of fluid and skin-based biomarkers. There is little research evidence for the treatment of pDLB, but pharmacological and non-pharmacological treatments for DLB may be discussed with patients. Non-pharmacological interventions such as diet, exercise, and cognitive stimulation may provide benefit, while evaluation and management of contributing factors like medications and sleep disturbances are vital. There is a need to expand research across diverse patient populations to address existing disparities in clinical trial participation. In conclusion, an early and accurate diagnosis of pDLB or pAD presents an opportunity for tailored interventions, improved healthcare outcomes, and enhanced quality of life for patients and care partners.

Reduced cardiac 123I-MIBG uptake is a robust biomarker of Lewy body disease in isolated rapid eye movement sleep behaviour disorder

Cardiac 123I-MIBG scintigraphy is used to assess the function of postganglionic presynaptic cardiac sympathetic nerve endings. 123I-MIBG cardiac uptake is markedly reduced in patients with isolated rapid eye movement sleep behaviour disorder, similar to Parkinson's disease and dementia with Lewy bodies. As a result, it can be used as an early biomarker of isolated rapid eye movement sleep behaviour disorder. Most patients with isolated rapid eye movement sleep behaviour disorder develop synucleinopathies: Parkinson's disease, dementia with Lewy bodies or multiple system atrophy. We aimed to investigate whether cardiac postganglionic denervation is present in patients with isolated rapid eye movement sleep behaviour disorder, as well as its possible usefulness as a marker for Lewy body disease status. This retrospective cohort study examined 306 patients (236 men and 70 women; mean age: 68.2 years; age range: 43-87 years) with polysomnography-confirmed isolated rapid eye movement sleep behaviour disorder who were followed for 1-3 months and underwent 123I-MIBG scintigraphy. We retrospectively analysed data from 306 patients with polysomnography-confirmed isolated rapid eye movement sleep behaviour disorder, and their longitudinal outcomes were documented at two centres. Among isolated rapid eye movement sleep behaviour disorder patients, reduced 123I-MIBG uptake was observed in the early and delayed images in 84.4 and 93.4% of patients, respectively, whereas 88.6% of the patients had a high washout rate. This large Japanese two-cohort study (n = 306) found that 91 patients (29.7%) developed an overt synucleinopathy (51 Parkinson's disease, 35 dementia with Lewy bodies, 4 multiple system atrophy, and 1 cerebellar ataxia) during a mean follow-up duration of 4.72 ± 3.94 years, with a conversion risk of 14.5% at 3 years, 25.4% at 5 years, 41.4% at 8 years and 52.5% at 10 years. On the other hand, among patients with heart-to-mediastinum ratio < 2.2 in the delayed images (n = 286), 85 (29.7%) developed Parkinson's disease or dementia with Lewy bodies during a mean follow-up duration of 4.71 ± 3.94 years, with a conversion risk of 14.5% at 3 years, 25.6% at 5 years, 42.0% at 8 years and 51.0% at 10 years. Among the 33 patients who underwent repeat 123I-MIBG scintigraphy, there was a progressive decline in uptake over the next 4.2 years, with patients exhibiting reduced uptake progressing to Parkinson's disease or dementia with Lewy bodies. In contrast, patients without decreased 123I-MIBG uptake progressed to multiple system atrophy. Reduced cardiac 123I-MIBG uptake was detected in over 90% of isolated rapid eye movement sleep behaviour disorder patients, with progression to Parkinson's disease or dementia with Lewy bodies, rather than multiple system atrophy, over time. Reduced 123I-MIBG uptake is a robust maker for Lewy body disease among isolated rapid eye movement sleep behaviour disorder patients.

[Dementia with Lewy bodies: old and new knowledge - Part 1: clinical aspects and diagnostics]

BACKGROUND

Dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia after Alzheimer's disease. Patients with DLB often have a poor prognosis, with worse outcomes than patients with Alzheimer's disease in terms of important parameters, such as quality of life, caregiver burden, health-related costs, frequency of hospital and nursing home admissions, shorter time to severe dementia, and lower survival. The DLB is frequently misdiagnosed and often undertreated. Therefore, it is critical to diagnose DLB as early as possible to ensure optimal care and treatment.

OBJECTIVE

The aim of this review article is to summarize the main recent findings on diagnostic tools, epidemiology and genetics of DLB.

RESULTS

Precise clinical diagnostic criteria exist for DLB that enable an etiologic assignment. Imaging techniques are used as standard in DLB, especially also to exclude non-neurodegenerative causes. In particular, procedures in nuclear medicine have a high diagnostic value.

DISCUSSION

The diagnosis is primarily based on clinical symptoms, although the development of in vivo neuroimaging and biomarkers is changing the scope of clinical diagnosis as well as research into this devastating disease.

The role of 123-I-MIBG cardiac scintigraphy in the differential diagnosis between dementia with Lewy bodies and Alzheimer's disease

Although detailed diagnostic guidelines are available, differentiating dementia with Lewy bodies from Alzheimer's disease is often difficult. 123-I-MIBG cardiac scintigraphy is one of the tools which have been proposed for the diagnostic procedure. The present review is aimed at evaluating the available literature about this topic. Studies assessing the use of this technique to differentiate between the two diseases have been examined and reported. Overall, despite a certain study-to-study variability, the available literature suggests that 123-I-MIBG cardiac scintigraphy is an effective tool in differentiating between the two diseases, with high sensitivity and specificity values. Although the large-scale application of this technique is limited by possible interactions with specific medications and comorbidities, the reported studies are supportive for the usefulness of this technique in clinical practice.

Comparison of Taiwanese and European Calibration Factors for Heart-to-Mediastinum Ratio in Multicenter 123I-mIBG Phantom Studies

Background: Cross-calibration of 123I-labeled meta-iodobenzylguanidine (mIBG) myocardial-derived indices is essential to extrapolate findings from several clinical centers. Here, we conducted a phantom study to generate conversion coefficients for the calibration of heart-to-mediastinum ratios and compare them between Taiwan and Europe. Methods: We used an acrylic phantom dedicated to 123I-mIBG planar imaging to calculate the conversion coefficients of 136 phantom images derived from 36 Taiwanese institutions. A European phantom image database including 191 images from 27 institutions was used. Conversion coefficients were categorized into five collimator types: low-energy (LE) high-resolution (LEHR), LE general-purpose (LEGP), extended LEGP (ELEGP), medium-energy (ME) GP (MEGP), and ME low-penetration (MELP) collimators. Results: The conversion coefficients were 0.53 ± 0.039, 0.59 ± 0.032, 0.79 ± 0.032, 0.96 ± 0.038, and 0.99 ± 0.050 for LEHR, LEGP, ELEGP, MEGP, and MELP collimators, respectively. The Taiwanese and European conversion coefficients for the LEHR, LEGP, and MELP collimators did not significantly differ. The coefficient of variation was slightly higher for the Taiwanese than the European conversion coefficients (3.7%-7.5% vs. 2.3%-5.6%). Conclusions: We calculated conversion coefficients for various types of collimators used in Taiwan using a 123I-mIBG phantom. In general, the Taiwanese and European conversion coefficients were comparable. These findings further corroborated and highlighted the need for 123I-mIBG standardization using the phantom-determined conversion coefficients.

Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson's Disease: A Comprehensive Review

Cardiac sympathetic denervation, as documented on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, is relatively sensitive and specific for distinguishing Parkinson's disease (PD) from other neurodegenerative causes of parkinsonism. The present study aims to comprehensively review the literature regarding the use of cardiac MIBG in PD. MIBG is an analog to norepinephrine. They share the same uptake, storage, and release mechanisms. An abnormal result in the cardiac MIBG uptake in individuals with parkinsonism can be an additional criterion for diagnosing PD. However, a normal result of cardiac MIBG in individuals with suspicious parkinsonian syndrome does not exclude the diagnosis of PD. The findings of cardiac MIBG studies contributed to elucidating the pathophysiology of PD. We investigated the sensitivity and specificity of cardiac MIBG scintigraphy in PD. A total of 54 studies with 3114 individuals diagnosed with PD were included. The data were described as means with a Hoehn and Yahr stage of 2.5 and early and delayed registration H/M ratios of 1.70 and 1.51, respectively. The mean cutoff for the early and delayed phases were 1.89 and 1.86. The sensitivity for the early and delayed phases was 0.81 and 0.83, respectively. The specificity for the early and delayed phases were 0.86 and 0.80, respectively.

Machine learning-based prediction of conversion coefficients for I-123 metaiodobenzylguanidine heart-to-mediastinum ratio

PURPOSE

We developed a method of standardizing the heart-to-mediastinal ratio in 123I-labeled meta-iodobenzylguanidine (MIBG) images using a conversion coefficient derived from a dedicated phantom. This study aimed to create a machine-learning (ML) model to estimate conversion coefficients without using a phantom.

METHODS

210 Monte Carlo (MC) simulations of 123I-MIBG images to obtain conversion coefficients using collimators that differed in terms of hole diameter, septal thickness, and length. Simulated conversion coefficients and collimator parameters were prepared as training datasets, then a gradient-boosting ML was trained to estimate conversion coefficients from collimator parameters. Conversion coefficients derived by ML were compared with those that were MC simulated and experimentally derived from 613 phantom images.

RESULTS

Conversion coefficients were superior when estimated by ML compared with the classical multiple linear regression model (root mean square deviations: 0.021 and 0.059, respectively). The experimental, MC simulated, and ML-estimated conversion coefficients agreed, being, respectively, 0.54, 0.55, and 0.55 for the low-; 0.74, 0.70, and 0.72 for the low-middle; and 0.88, 0.88, and 0.88 for the medium-energy collimators.

CONCLUSIONS

The ML model estimated conversion coefficients without the need for phantom experiments. This means that conversion coefficients were comparable when estimated based on collimator parameters and on experiments.

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.

Clinical characteristics and potential association to Parkinson's disease and dementia with Lewy bodies in patients with major depressive disorder who received maintenance electroconvulsive therapy: a retrospective chart review study

BACKGROUND

Maintaining remission after electroconvulsive therapy (ECT) is clinically relevant in patients with depression, and maintenance ECT has been introduced in patients who fail to maintain remission after ECT. However, the clinical characteristics and biological background of patients who receive maintenance ECT are poorly understood. Thus, this study aimed to examine the clinical background of patients who underwent maintenance ECT.

METHODS

Patients with major depressive disorder who underwent ECT followed by maintenance ECT (mECT group) and those who did not (acute ECT [aECT] group) were included. Clinical characteristics, including the results of neuroimaging examinations for Parkinson's disease (PD) and dementia with Levy body (DLB) such as myocardial 123I-metaiodobenzylguanidine (MIBG) scintigraphy and dopamine transporter imaging single-photon emission computerized tomography (DaT-SPECT), were compared between the groups.

RESULTS

In total, 13 and 146 patients were included in the mECT and aECT groups, respectively. Compared to the aECT group, the mECT group showed a significantly higher prevalence of melancholic features (92.3% vs. 27.4%, p < 0.001) and catatonic features (46.2% vs. 9.6%, p = 0.002). Overall, 8 of the 13 patients in the mECT group and 22 of the 146 patients in the aECT group underwent neuroimaging examinations for PD/DLB. The rate of patients examined is significantly higher in the mECT group than in the aECT group (61.5% vs. 11.2%, p < 0.001). Among the groups examined, 7/8 patients in the mECT group and 16/22 patients in the aECT group showed relevant neuroimaging findings for PD/DLB; the positive rate was not significantly different between the two groups (87.5% vs. 72.7%, p = 0.638).

CONCLUSIONS

Patients who receive acute and maintenance ECT may have underlying neurodegenerative diseases, including PD/DLB. Investigating the neurobiology of patients who receive maintenance ECT is important for developing appropriate treatments for depression.

Biomarkers of diagnosis, prognosis, pathogenesis, response to therapy: Convergence or divergence? Lessons from Alzheimer's disease and synucleinopathies

Alzheimer's disease (AD) is the most common disorder associated with cognitive impairment. Recent observations emphasize the pathogenic role of multiple factors inside and outside the central nervous system, supporting the notion that AD is a syndrome of many etiologies rather than a "heterogeneous" but ultimately unifying disease entity. Moreover, the defining pathology of amyloid and tau coexists with many others, such as α-synuclein, TDP-43, and others, as a rule, not an exception. Thus, an effort to shift our AD paradigm as an amyloidopathy must be reconsidered. Along with amyloid accumulation in its insoluble state, β-amyloid is becoming depleted in its soluble, normal states, as a result of biological, toxic, and infectious triggers, requiring a shift from convergence to divergence in our approach to neurodegeneration. These aspects are reflected-in vivo-by biomarkers, which have become increasingly strategic in dementia. Similarly, synucleinopathies are primarily characterized by abnormal deposition of misfolded α-synuclein in neurons and glial cells and, in the process, depleting the levels of the normal, soluble α-synuclein that the brain needs for many physiological functions. The soluble to insoluble conversion also affects other normal brain proteins, such as TDP-43 and tau, accumulating in their insoluble states in both AD and dementia with Lewy bodies (DLB). The two diseases have been distinguished by the differential burden and distribution of insoluble proteins, with neocortical phosphorylated tau deposition more typical of AD and neocortical α-synuclein deposition peculiar to DLB. We propose a reappraisal of the diagnostic approach to cognitive impairment from convergence (based on clinicopathologic criteria) to divergence (based on what differs across individuals affected) as a necessary step for the launch of precision medicine.

Sex differences in dementia with Lewy bodies: Focused review of available evidence and future directions

In this review, we summarize the current knowledge on sex differences in dementia with Lewy bodies (DLB) relating to epidemiology, clinical features, neuropathology, biomarkers, disease progression, and caregiving. While many studies show a higher DLB prevalence in men, this finding is inconsistent and varies by study approach. Visual hallucinations may be more common and occur earlier in women with DLB, whereas REM sleep behavior disorder may be more common and occur earlier in men. Several studies report a higher frequency of parkinsonism in men with DLB, while the frequency of fluctuations appears similar between sexes. Women tend to be older, have greater cognitive impairment at their initial visit, and are delayed in meeting DLB criteria compared to men. Women are also more likely to have Lewy body disease with co-existing AD-related pathology than so-called "pure" Lewy body disease, while men may present with either. Research is mixed regarding the impact of sex on DLB progression. Biomarker and treatment research assessing for sex differences is lacking. Women provide the majority of caregiving in DLB but how this affects the caregiving experience is uncertain. Gaining a better understanding of sex differences will be instrumental in aiding future development of sex-specific strategies in DLB for early diagnosis, care, and drug development.

GBA1 Gene Mutations in α-Synucleinopathies-Molecular Mechanisms Underlying Pathology and Their Clinical Significance

α-Synucleinopathies comprise a group of neurodegenerative diseases characterized by altered accumulation of a protein called α-synuclein inside neurons and glial cells. This aggregation leads to the formation of intraneuronal inclusions, Lewy bodies, that constitute the hallmark of α-synuclein pathology. The most prevalent α-synucleinopathies are Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). To date, only symptomatic treatment is available for these disorders, hence new approaches to their therapy are needed. It has been observed that GBA1 mutations are one of the most impactful risk factors for developing α-synucleinopathies such as PD and DLB. Mutations in the GBA1 gene, which encodes a lysosomal hydrolase β-glucocerebrosidase (GCase), cause a reduction in GCase activity and impaired α-synuclein metabolism. The most abundant GBA1 gene mutations are N370S or N409S, L444P/L483P and E326K/E365K. The mechanisms by which GCase impacts α-synuclein aggregation are poorly understood and need to be further investigated. Here, we discuss some of the potential interactions between α-synuclein and GCase and show how GBA1 mutations may impact the course of the most prevalent α-synucleinopathies.

A prospective multicenter validation study of a machine learning algorithm classifier on quantitative electroencephalogram for differentiating between dementia with Lewy bodies and Alzheimer’s dementia

Background and purpose

An early and accurate diagnosis of Dementia with Lewy bodies (DLB) is critical because treatments and prognosis of DLB are different from Alzheimer’s disease (AD). This study was carried out in Japan to validate an Electroencephalography (EEG)-derived machine learning algorithm for discriminating DLB from AD which developed based on a database of EEG records from two different European countries.

Methods

In a prospective multicenter study, patients with probable DLB or with probable AD were enrolled in a 1:1 ratio. A continuous EEG segment of 150 seconds was recorded, and the EEG data was processed using MC-004, the EEG-based machine learning algorithm, with all clinical information blinded except for age and gender.

Results

Eighteen patients with probable DLB and 21 patients with probable AD were the included for the analysis. The performance of MC-004 differentiating probable DLB from probable AD was 72.2% (95% CI 46.5–90.3%) for sensitivity, 85.7% (63.7–97.0%) for specificity, and 79.5% (63.5–90.7%) for accuracy. When limiting to subjects taking ≤5 mg donepezil, the sensitivity was 83.3% (95% CI 51.6–97.9), the specificity 89.5% (66.9–98.7), and the accuracy 87.1% (70.2–96.4).

Conclusions

MC-004, the EEG-based machine learning algorithm, was able to discriminate between DLB and AD with fairly high accuracy. MC-004 is a promising biomarker for DLB, and has the potential to improve the detection of DLB in a diagnostic process.

Autopsy Validation of the Diagnostic Accuracy of 123I-Metaiodobenzylguanidine Myocardial Scintigraphy for Lewy Body Disease

BACKGROUND AND OBJECTIVES

¹²³I-meta-iodobenzyl-guanidine (¹²³I-MIBG) myocardial scintigraphy is employed as a diagnostic imaging test to differentiate Lewy body diseases (LBDs), including Parkinson's disease and dementia with Lewy bodies, from other similar diseases. However, its diagnostic accuracy lacks validation compared with that of the gold standard. We aimed to validate the diagnostic accuracy of ¹²³I-MIBG myocardial scintigraphy for LBD against autopsy, the gold standard.

METHODS

This retrospective, cross-sectional study included consecutive autopsy patients from the Brain Bank for Aging Research who had undergone ¹²³I-MIBG myocardial scintigraphy. We compared the ¹²³I-MIBG myocardial scintigraphy findings with autopsy findings. Furthermore, the proportion of residual tyrosine hydroxylase (TH)-immunoreactive sympathetic fibers in the anterior wall of the left ventricle was investigated to assess the condition of the cardiac sympathetic nerves assumed to cause reduced ¹²³I-MIBG uptake in LBDs.

RESULTS

We analyzed the data of 56 patients (30 with pathologically confirmed LBDs and 26 without LBD pathology). Compared with the neuropathological diagnosis, the early heart-to-mediastinum (H/M) ratio had a sensitivity and specificity of 70.0% (95% confidence interval [CI]: 50.6-85.3%) and 96.2% (95% CI: 80.4-99.9%), respectively. The delayed H/M ratio had a sensitivity and specificity of 80.0% (95% CI: 61.4-92.3%) and 92.3% (95% CI: 74.9-99.1%), respectively. The washout rate had a sensitivity and specificity of 80.0% (95% CI: 61.4-92.3%) and 84.6% (95% CI: 65.1-95.6%), respectively. The proportion of residual TH-immunoreactive cardiac sympathetic fibers strongly correlated with the amount of cardiac ¹²³I-MIBG uptake when assessed with early and delayed H/M ratio values (correlation coefficient: 0.75 and 0.81, respectively; p < 0.001).

DISCUSSION

This clinicopathological validation study revealed that ¹²³I-MIBG myocardial scintigraphy could robustly differentiate LBDs from similar diseases. Abnormal ¹²³I-MIBG myocardial scintigraphy findings strongly support the presence of LBD and cardiac sympathetic denervation. However, LBD pathology should not necessarily be excluded by normal myocardial scintigraphy results, especially when other biomarkers suggest the presence of comorbid Alzheimer's disease pathology.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that ¹²³I-MIBG myocardial scintigraphy accurately identifies patients with LBD.

Dynamic planar scintigraphy for the rapid kinetic measurement of myocardial 123I-MIBG turnover can identify Lewy body disease

BACKGROUND

Using two static scans for ¹²³I-meta-iodobenzyl-guanidine (¹²³I-MIBG) myocardial scintigraphy ignores the dynamic response from vesicular trapping in nerve terminals. Moreover, the long pause between scans is impractical for patients with Lewy body diseases (LBDs). Here, we optimized indices that capture norepinephrine kinetics, tested their diagnostic performance, and determined the differences in ¹²³I-MIBG performance among disease groups.

METHODS

We developed a new 30-min protocol for ¹²³I-MIBG dynamic planar imaging for suspected LBD patients. Pharmacokinetic modelling of time-activity curves (TACs) was used to calculate three new indices: unidirectional uptake of ¹²³I-MIBG to vesicular trapping (iUp), rate of myocardial ¹²³I-MIBG loss (iLoss), and non-specific fractional distribution of ¹²³I-MIBG in the interstitial space. We compared the performance of the new and existing indices with regard to discrimination of patients with or without LBDs. Subgroup analysis was performed to examine differences in ¹²³I-MIBG turnover between patients in a dementia with Lewy bodies (DLB) group and two Parkinson's disease (PD) groups, one with and the other without REM sleep behaviour disorder (RBD).

RESULTS

iLoss was highly discriminative, particularly for patients with low myocardial ¹²³I-MIBG trapping, and the new indices outperformed existing ones. ROC analysis revealed that the AUC of iLoss (0.903) was significantly higher than that of early HMR (0.863), while comparable to that of delayed HMR (0.892). The RBD-positive PD group and the DLB group had higher turnover rates than the RBD-negative PD group, indicating a potential association between prognosis and iLoss.

CONCLUSION

¹²³I-MIBG turnover can be quantified in 30 min using a three-parameter model based on ¹²³I-MIBG TACs. The discriminatory performance of the new model-based indices might help explain the neurotoxicity or neurodegeneration that occurs in LBD patients.

Neuroimaging alterations in dementia with Lewy bodies and neuroimaging differences between dementia with Lewy bodies and Alzheimer's disease: An activation likelihood estimation meta-analysis

Aims

The aim of this study was to identify brain regions with local, structural, and functional abnormalities in dementia with Lewy bodies (DLB) and uncover the differences between DLB and Alzheimer's disease (AD). The neural networks involved in the identified abnormal brain regions were further described.

Methods

PubMed, Web of Science, OVID, Science Direct, and Cochrane Library databases were used to identify neuroimaging studies that included DLB versus healthy controls (HCs) or DLB versus AD. The coordinate‐based meta‐analysis and functional meta‐analytic connectivity modeling were performed using the activation likelihood estimation algorithm.

Results

Eleven structural studies and fourteen functional studies were included in this quantitative meta‐analysis. DLB patients showed a dysfunction in the bilateral inferior parietal lobule and right lingual gyrus compared with HC patients. DLB patients showed a relative preservation of the medial temporal lobe and a tendency of lower metabolism in the right lingual gyrus compared with AD. The frontal‐parietal, salience, and visual networks were all abnormally co‐activated in DLB, but the default mode network remained normally co‐activated compared with AD.

Conclusions

The convergence of local brain regions and co‐activation neural networks might be potential specific imaging markers in the diagnosis of DLB. This might provide a pathway for the neural regulation in DLB patients, and it might contribute to the development of specific interventions for DLB and AD.

Frontal lobe dysfunction is associated with reduced DAT-SPECT accumulation in Lewy body disease

INTRODUCTION

Lewy body disease (LBD) causes olfactory or cognitive dysfunction even before motor symptoms emerge. Recent reports indicate that the dopamine transporter (DAT), which can be imaged using single-photon emission computed tomography (¹²³I-ioflupane SPECT), is related to olfactory and cognitive dysfunction in LBD patients. We suspected that decreased cerebral blood flow (CBF) in the frontal lobe might be involved in these relationships. If so, then the results of these examinations may be useful in assessing the pathological progression of Lewy bodies.

METHODS

We retrospectively analyzed the data of 139 de novo consecutive patients with LBD. We used the Odor Stick Identification Test for Japanese (OSIT-J) and the Frontal Assessment Battery (FAB) to evaluate olfactory and frontal lobe dysfunction, respectively. Among the 139 patients, ultimately 84 patients were analyzed and underwent ¹²³I-ioflupane SPECT within 3 months (before or after) of the OSIT-J and FAB. We categorized patients on the basis of whether frontal lobe CBF was reduced (n = 28) or normal (n = 56).

RESULTS

The average OSIT-J and FAB scores were 4.0 and 14.1, respectively, and the scores on the two tests were significantly correlated. Furthermore, OSIT-J scores were significantly correlated with the specific binding ratio (SBR) in both groups. The SBR was correlated with FAB scores in patients with reduced CBF in the frontal lobe, but not in those with normal CBF.

CONCLUSION

Frontal lobe dysfunction and striatum dysfunction are correlated in LBD patients only after CBF has declined. Also, there is a time lag in the appearance of olfactory dysfunction and frontal lobe dysfunction in LBD patients. As with pathological development, olfaction is impaired earliest, followed by striatal, and then frontal lobe dysfunction.

40 Years Anniversary of Cardiac 123I-mIBG Imaging: State of the Heart

Purpose of Review

This narrative review reflects on the body of evidence on cardiac 123I-mIBG imaging that has accumulated since the introduction in the late 1970s and focusses on to what extent cardiac 123I-mIBG imaging has fulfilled its potential in cardiology especially.

Recent Findings

In contrast to the linear relationship between 123I-mIBG-derived parameters and overall prognosis in heart failure, there seems a “bell-shape” curve for 123I-mIBG-derived parameters and arrhythmic events. In addition, there is a potential clinical role for cardiac 123I-mIBG in optimizing patient selection for expensive devices (i.e., ICD and CRT). This needs of course to be established in future trials.

Summary

Cardiac 123I-mIBG imaging is, despite the numerous of studies, sometimes mistakenly seen as a nice to have technique rather than a must have imaging modality. Although cardiac 123I-mIBG imaging has grown and matured over the years, its full clinical potential has still not been tested to the maximum.

Comorbid alpha synucleinopathies in idiopathic normal pressure hydrocephalus

OBJECTIVE

This study aimed to determine the prevalence and clinical features of Parkinson's disease (PD)/PD dementia (PD/PDD) or dementia with Lewy bodies (DLB) in idiopathic normal pressure hydrocephalus (iNPH).

METHODS

Patients with iNPH who were admitted to the Department of Neurology, Juntendo University School of Medicine over the past 10 years have been retrospectively analyzed. The diagnosis of iNPH and concomitant PD/PDD or DLB was established using diagnostic criteria. Motor symptoms were assessed by the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III. ¹²³I-ioflupane single-photon emission computed tomography (DaT-SPECT) and cerebrospinal fluid (CSF) real-time quaking-induced conversion (RT-QuIC)-based assay were performed for alpha synuclein aggregation.

RESULTS

Overall, 79 patients met the criteria for iNPH, of which 34 developed iNPH without accompanying disorders (iNPHa; 43%), 23 developed iNPH with comorbid PD/PDD (iNPHc + PD/PDD; 29.1%), and 8 developed iNPH with comorbid DLB (iNPHc + DLB; 10.1%). Significant differences in facial expansion and upper-limb parkinsonism were observed with a comorbidity of either PD/PDD or DLB. The specific binding ratio (SBR) of DaTscan was reduced in iNPHa (p = 0.02), but it reduced further with comorbid PD/PDD (p < 0.01) or DLB (p < 0.01). RT-QuIC was positive for all 13 comorbid PD/PDD and negative for all 19 iNPHa.

CONCLUSION

These results highlight that synucleinopathies coexist with iNPH. These can be differentiated by performing DaTscan and RT-QuIC, which can affect its clinical features.

Psychotic Features Among Patients in the Prodromal Stage of Dementia with Lewy Bodies During Longitudinal Observation

BACKGROUND

Many cases of dementia with Lewy bodies (DLB) present with various psychotic features, including hallucinations, depression, catatonia, and delusions before the onset of cognitive impairment. However, the characteristic features of these psychotic symptoms in prodromal DLB have not been sufficiently described.

OBJECTIVE

To clarify and describe the psychotic features of prodromal DLB before overt cognitive impairment.

METHODS

The authors analyzed the characteristic psychotic features of prodromal DLB in 21 subjects who developed severe psychotic symptoms without dementia and were diagnosed as DLB after the longitudinal observation period. They were then confirmed to have DLB through indicative and supportive biomarkers of scintigraphy.

RESULTS

The psychotic features included a wide variety of symptoms, but convergent to three principal categories: catatonia, delusions-hallucinations, and depression and/or mania. Catatonia was observed in nine cases, five were delusional-hallucinatory, and seven were manic and/or depressive. Seven of the 21 cases exhibited delirium during longitudinal observation. A psychotic state repeatedly appeared without any trigger in 20 of the 21 patients. All subjects developed cognitive impairment at 9.1±4.6 (mean±SD) years after the initial appearance of psychotic symptoms, and subsequently diagnosed with DLB at 71.3±6.1 (mean±SD) years.

CONCLUSION

Elderly patients with psychotic symptoms, such as catatonia, delusion-hallucination, manic and/or depressive features, and delirium without dementia, could indicate symptomatic psychosis or a prodromal stage of any neurocognitive disorder such as DLB. Therefore, further extensive workout (e.g., radioisotope neuroimaging) is required to avoid misdiagnosis.

Cardiac 123I-MIBG normal uptake values are population-specific: Results from a cohort of controls over 60 years of age

PURPOSE

Cardiac 123I-MIBG image interpretation is affected by population differences and technical factors. We recruited older adults without cognitive decline and compared their cardiac MIBG uptake with results from the literature.

METHODS

Phantom calibration confirmed that cardiac uptake results from Japan could be applied to our center. We recruited 31 controls, 17 individuals with dementia with Lewy bodies (DLB) and 15 with Alzheimer's disease (AD). Images were acquired 20 minutes and four hours after injection using Siemens cameras with medium-energy low-penetration (MELP) collimators. Local normal heart-to-mediastinum (HMR) ratios were compared to Japanese results.

RESULTS

Siemens gamma cameras with MELP collimators should give HMRs very close to the calibrated values used in Japan. However, our cut-offs with controls were lower at 2.07 for early and 1.86 for delayed images. Applying our lower cut-off to the dementia patients may increase the specificity of cardiac MIBG imaging for DLB diagnosis in a UK population without reducing sensitivity.

CONCLUSIONS

Our local HMR cut-off values are lower than in Japan, higher than in a large US study but similar to those found in another UK center. UK centers using other cameras and collimators may need to use different cut-offs to apply our results.

Neuroimaging in Dementia With Lewy Bodies

Dementia with Lewy bodies (DLB) is one of the most common forms of dementia. It can present as neurocognitive decline, visual hallucinations, and concomitant symptoms of rapid eye movement (REM) sleep behavior disorder. Early diagnosis remains one of the cornerstones of managing this form of neurocognitive disorder but, often, making an early and accurate diagnosis can prove to be challenging. For this article, our goal was to review the utility of various neuroimaging modalities in making a swift and accurate diagnosis of DLB. We used PubMed to look for helpful, informative, and peer-reviewed articles. We discussed the role of a plethora of different imaging techniques, ranging from structural imaging like computed tomography (CT) and magnetic resonance imaging (MRI) to molecular imaging (single-photon emission computed tomography, positron emission to- tomography) as a diagnostic tool for DLB. We arrived at the conclusion that these novel neuroimaging modalities have already proven to be very helpful in ruling out differentials and making an early diagnosis of DLB. However, ongoing research is required to increase the diagnostic accuracy, leading to the early identification and treatment of DLB.

Early diagnosis of prodromal dementia with Lewy bodies using clinical history of probable REM sleep behaviour disorder and cardiac 123 I-MIBG scintigraphy in memory clinics

BACKGROUND

Rapid eye movement sleep behaviour disorder (RBD) is associated with reduced cardiac ¹²³ I-metaiodobenzylguanidine (MIBG) uptake and often precedes the onset of Lewy body (LB) disorders. We investigated the role of cardiac ¹²³ I-MIBG scintigraphy in relation to probable RBD for the clinical diagnosis of prodromal dementia with Lewy bodies (DLB) in memory clinics.

METHODS

We reviewed clinical profiles of 60 consecutive patients who underwent cardiac ¹²³ I-MIBG scintigraphy in our memory clinics. The diagnostic threshold of 2.20 was used as the cut-off for the heart-to-mediastinum ratio at the delayed phase.

RESULTS

Cardiac ¹²³ I-MIBG abnormality was identified in 28 patients at baseline; six were cognitively unimpaired, six had mild cognitive impairment (MCI)-LB, and 16 had probable DLB based on the National Institute on Aging and Alzheimer's Association Research Framework. Although the number of core features increased in accordance with the progression of three cognitive categories, there were no differences in the prevalence of probable RBD and the cardiac MIBG scintigraphy indices among them. During the observation period, two cognitively unimpaired patients with probable RBD progressed to MCI-LB, and three MCI-LB patients with probable RBD developed DLB. The prevalence of final diagnosis of probable MCI-LB or DLB was significantly higher in these patients (85%) than the remaining 32 patients without (9%). Of 25 patients with probable RBD, 22 (88%) had a cardiac ¹²³ I-MIBG abnormality regardless of cognitive conditions. Only one patient consulted a sleep centre for the abnormal sleep behaviour before visiting our memory clinics. Regarding the gender differences, male predominance was not identified and sleep-related injury more frequently occurred in men (7/12, 58%) than in women (1/10, 10%).

CONCLUSIONS

Proactive detection of probable RBD plus cardiac ¹²³ I-MIBG abnormality provides the opportunity for an early diagnosis of prodromal DLB in memory clinics. This approach warrants further follow-up studies with polysomnographic and pathological verification.

Genetic Architecture and Molecular, Imaging and Prodromic Markers in Dementia with Lewy Bodies: State of the Art, Opportunities and Challenges

Dementia with Lewy bodies (DLB) is one of the most common causes of dementia and belongs to the group of α-synucleinopathies. Due to its clinical overlap with other neurodegenerative disorders and its high clinical heterogeneity, the clinical differential diagnosis of DLB from other similar disorders is often difficult and it is frequently underdiagnosed. Moreover, its genetic etiology has been studied only recently due to the unavailability of large cohorts with a certain diagnosis and shows genetic heterogeneity with a rare contribution of pathogenic mutations and relatively common risk factors. The rapid increase in the reported cases of DLB highlights the need for an easy, efficient and accurate diagnosis of the disease in its initial stages in order to halt or delay the progression. The currently used diagnostic methods proposed by the International DLB consortium rely on a list of criteria that comprises both clinical observations and the use of biomarkers. Herein, we summarize the up-to-now reported knowledge on the genetic architecture of DLB and discuss the use of prodromal biomarkers as well as recent promising candidates from alternative body fluids and new imaging techniques.

Molecular and Anatomical Imaging of Dementia With Lewy Bodies and Frontotemporal Lobar Degeneration

Dementia with Lewy bodies (DLB) and frontotemporal lobar degeneration (FTLD) are common causes of dementia. Early diagnosis of both conditions is challenging due to clinical and radiological overlap with other forms of dementia, particularly Alzheimer's disease (AD). Structural and functional imaging combined can aid differential diagnosis and help to discriminate DLB or FTLD from other forms of dementia. Imaging of DLB involves the use of ¹²³I-FP-CIT SPECT and ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG), both of which have an established role distinguishing DLB from AD. AD is also characterised by more pronounced atrophy of the medial temporal lobe structures when compared to DLB and these can be assessed at MR using the Medial Temporal Atrophy Scale. ¹⁸F-FDG-PET is used as a supportive biomarker for the diagnoses of DLB and can distinguish DLB from AD with high accuracy. Polysomnography and electroencephalography also have established roles in the diagnoses of DLB. FTLD is a heterogenous group of neurodegenerative disorders characterised pathologically by abnormally aggregated proteins. Clinical subtypes include behavioral variant FTD (bvFTD), primary progressive aphasia (PPA), which can be subdivided into semantic variant PPA (svPPA) or nonfluent agrammatic PPA (nfaPPA) and FTD associated with motor neuron disease (FTD-MND). Structural imaging is often the first step in making an image supported diagnoses of FTLD. Regional patterns of atrophy can be assessed on MR and graded according to the global cortical atrophy scale. FTLD is typically associated with atrophy of the frontal and temporal lobes. The patterns of atrophy are associated with the specific clinical subtypes, underlying neuropathology and genetic mutations although there is significant overlap. ¹⁸F-FDG-PET is useful for distinguishing FTLD from other forms of dementia and focal areas of hypometabolism can often precede atrophy identified on structural MR imaging. There are currently no biomarkers with which to unambiguously diagnose DLB or FTLD and both conditions demonstrate a wide range of heterogeneity. A combined approach of structural and functional imaging improves diagnostic accuracy in both conditions.

Biomarker Use for Dementia With Lewy Body Diagnosis: Survey of US Experts

BACKGROUND

Dementia with Lewy body (DLB) diagnostic criteria define "indicative" and "supportive" biomarkers, but clinical practice patterns are unknown.

METHODS

An anonymous survey querying clinical use of diagnostic tests/biomarkers was sent to 38 center of excellence investigators. The survey included "indicative" biomarkers (dopamine transporter scan, myocardial scintigraphy, polysomnography), "supportive" biomarkers [magnetic resonance imaging (MRI)], positron emission tomography, or single-photon emission computed tomography perfusion/metabolism scans, quantitative electroencephalography), and other diagnostic tests (neuropsychological testing, cerebrospinal fluid analysis, genetics). Responses were analyzed descriptively.

RESULTS

Of the 22 respondents (58%), all reported the capability to perform neuropsychological testing, MRI, polysomnography, dopamine transporter scans, positron emission tomography/single-photon emission computed tomography scans, and cerebrospinal fluid analysis; 96% could order genetic testing. Neuropsychological testing and MRI were the most commonly ordered tests. Diagnostic testing beyond MRI and neuropsychological testing was most helpful in the context of "possible" DLB and mild cognitive impairment and to assist with differential diagnosis. Myocardial scintigraphy and electroencephalograpy use were rare.

CONCLUSIONS AND RELEVANCE

Neuropsychological testing and MRI remain the most widely used diagnostic tests by DLB specialists. Other tests-particularly indicative biomarkers-are used only selectively. Research is needed to validate existing potential DLB biomarkers, develop new biomarkers, and investigate mechanisms to improve DLB diagnosis.

Calibrated scintigraphic imaging procedures improve quantitative assessment of the cardiac sympathetic nerve activity

The ¹²³I-labeled meta-iodobenzylguanidine (MIBG) is an analogue of noradrenaline that can evaluate cardiac sympathetic activity in scintigraphy. Quantitative analysis of ¹²³I-MIBG images has been verified in patients with heart failure and neurodegenerative diseases. However, quantitative results differ due to variations in scintigraphic imaging procedures. Here, we created and assessed the clinical feasibility of a calibration method for ¹²³I-MIBG imaging. The characteristics of scintigraphic imaging systems were determined using an acrylic calibration phantom to generate a multicenter phantom imaging database. Calibration factors corresponding to the scintigraphic imaging procedures were calculated from the database and applied to a clinical study. The results of this study showed that the calibrated analysis eliminated inter-institutional differences among normal individuals. In summary, our standardization methodology for ¹²³I-MIBG scintigraphy could provide the basis for improved diagnostic precision and better outcomes for patients.

Synuclein in neurodegeneration

Neurodegenerative diseases are a heterogeneous group of disorders characterized by gradual progressive neuronal loss in the central nervous system. Unfortunately, the pathogenesis of many of these diseases remains unknown. Synucleins are a family of small, highly charged proteins expressed predominantly in neurons. Following their discovery, much has been learned about their structure, function, interaction with other proteins and role in neurodegenerative disease over the last two decades. One of these proteins, α-Synuclein (α-Syn), appears to be involved in many neurodegenerative disorders. These include Parkinson's disease (PD), dementia with Lewy bodies (DLB), Rapid Eye Movement Sleep Behavior Disorder (RBD) and Pure Autonomic Failure (PAF), i.e., collectively termed α-synucleinopathies. This review focuses on α-Syn dysfunction in neurodegeneration and assesses its role in synucleinopathies from a biochemical, genetic and neuroimaging perspective.

Characteristics of initial symptoms and symptoms at diagnosis in probable dementia with Lewy body disease: incidence of symptoms and gender differences

AIM

Although dementia with Lewy bodies (DLB) is characterized by a variety of initial symptoms, there are almost no reports of the initial symptoms of DLB assessed in a large number of cases. We retrospectively evaluated the initial symptoms of 234 participants with DLB and DLB-related symptoms at diagnosis and characterized any gender differences in the symptom profiles.

METHODS

This study consisted of 234 participants with probable DLB who met the diagnostic criteria outlined in the Fourth Consensus Report of the DLB Consortium (2017). DLB was confirmed based on several characteristic biomarkers for dopamine transporter imaging with ¹²³ I-N-omega-fluoropropyl-2-beta-carbomethoxy-3-beta (4-iodophenyl) nortropane single-photon emission computed tomography, ¹²³ I-metaiodobenzylguanidine myocardial scintigraphy, and brain perfusion measured with single photon emission computed tomography. In addition, core and supportive clinical features were considered in the diagnosis.

RESULTS

Initial symptoms included cognitive impairment (41.9%) and psychiatric symptoms (i.e. visual and auditory hallucinations, delusions, and depression) (42.3%). Almost half of the women initially presented with psychiatric symptoms, with significantly more women than men presenting with auditory hallucinations. In contrast, men had a significantly higher rate of rapid eye movement sleep behaviour disorder (RBD) than women did. At diagnosis, DLB-related symptoms differed between men and women, with male patients exhibiting significantly more RBD, parkinsonism, hyposmia, and syncope than female patients. Moreover women presented significantly more often with auditory hallucinations than did men.

CONCLUSIONS

Our results indicate that there are gender differences in the initial symptoms of DLB, as well as in the presentation of subsequent symptoms observed at diagnosis. There was a higher incidence of RBD in men, whereas women had a higher incidence of psychotic symptoms.

Clinical and pathological features affecting cardiac sympathetic denervation in autopsy-confirmed dementia with Lewy bodies

BACKGROUND AND PURPOSE

The aim was to clarify the features affecting cardiac sympathetic denervation in autopsy-confirmed dementia with Lewy bodies (DLB) patients.

METHODS

Fifty-four autopsy-confirmed DLB patients were enrolled. Tissue samples of the left ventricular anterior wall were immunostained with anti-tyrosine hydroxylase antibody to identify catecholaminergic nerve axons. Immunostained areas were quantified as residual cardiac sympathetic nerve (CSN) axons and the relationship between the degree of residual CSN axons and clinical and neuropathological features was examined.

RESULTS

Virtually all patients showed small amounts of residual CSN axons (0.87%, range 0.02%-9.98%), with 50 patients (92.6%) showing <2.0% of residual axons. The patients who showed psychological symptoms within the first year of the disease had significantly more residual CSN axons than the remaining patients did (1.50% vs. 0.40%, P < 0.01). Patients with a short disease duration and neocortical-type Lewy body pathology tended to have more preserved CSN axons, although this difference was not statistically significant. Fifty-three patients (98.1%) who had neurofibrillary tangles in the brain and strong concomitant Alzheimer's disease pathology also had statistically significantly more preserved CSN axons. The patient with the most preserved CSN axons showed different characteristics from the results, except for the first symptom.

CONCLUSION

Psychological symptoms within the first year of the disease, a short disease duration, neocortical-type Lewy body pathology and strong concomitant Alzheimer's disease pathology may be related to mild CSN degeneration in DLB patients. Thus, DLB patients with broad Lewy body pathology in the brain in the early stages may show mild CSN degeneration.

Cardiac 123I-MIBG planar heart to mediastinum ratios depend on patient size; phantom studies suggest SPECT-CT could improve quantification

INTRODUCTION

Planar ¹²³I-MIBG (meta-iodobenzylguanidine) cardiac imaging is listed as an indicative biomarker in the 2017 international consensus criteria for the diagnosis of dementia with Lewy bodies. There has been very little research into the relationship between apparent cardiac uptake and patient size, or in the possible advantage of attenuation and scatter corrected SPECT-CT compared to planar imaging. We aimed to evaluate this in both a chest phantom and in older adults with normal cognition.

MATERIALS AND METHODS

An anthropomorphic chest phantom was filled with ¹²³I solution using activities typical of healthy subjects. The phantom was scanned on a Siemens Intevo gamma camera with MELP collimators using both planar and SPECT-CT techniques. Further scans were acquired with a PMMA chest plate added, then water filled plastic breasts. The SPECT-CT images were reconstructed using a resolution recovery OSEM method with and without attenuation and scatter correction (ACSC) applied. Twenty-nine adults over 60 years of age (mean 75.2 ± 8.3 years) underwent planar cardiac MIBG imaging, followed by SPECT-CT. SPECT images were reconstructed as above. Heart-to-mediastinum ratios (HMRs) were calculated for planar and SPECT images.

RESULTS

Phantom planar HMR decreased by 20% with the PMMA chest plate added; 39% with plate and breasts. ACSC SPECT cardiac counts showed less dependence on phantom size than SPECT without ACSC (3% versus 37%). The body mass indices (BMI) of the older adults ranged from 22 to 38. There was a significant linear relationship between planar HMR and BMI (R² = 0.44, p<0.01), but not for ACSC SPECT. However, there was no significant difference between the slopes for planar and ACSC SPECT (p = 0.11).

CONCLUSION

Planar cardiac ¹²³I-MIBG HMR results are correlated with BMI. Phantom results suggest that ACSC SPECT can correct for patient size. A large patient population or clinical database would be required to demonstrate a clinical effect.

A comparison of visual and semiquantitative analysis methods for planar cardiac 123I-MIBG scintigraphy in dementia with Lewy bodies

OBJECTIVES

Cardiac I-MIBG imaging is an established technique for the diagnosis of dementia with Lewy bodies but various analysis methods are reported in the literature. We assessed different methods in the same cohort of patients to inform best practice.

PATIENTS AND METHODS

Seventeen patients with dementia with Lewy bodies, 15 with Alzheimer's disease and 16 controls were included. Planar images were acquired 20 min and 4 h after injection. Nine operators produced heart-to-mediastinum ratios (HMRs) using freehand and 6, 7 and 8 cm diameter circular cardiac regions. Interoperator variation was measured using the coefficient of variation. HMR differences between methods were assessed using analysis of variance. Seven raters assessed the images visually. Accuracy was compared using receiver operating characteristic analysis.

RESULTS

There were significant differences in HMR between region methods (P=0.006). However, with optimised cut-offs there was no significant difference in accuracy (P=0.2-1.0). The sensitivity was 65-71% and specificity 100% for all HMR methods. Variation was lower with fixed regions than freehand (P<0.001). Visual rating sensitivity and specificity were 65 and 77% on early images and 76 and 71% on delayed images. There was no significant difference in HMR between early and delayed images (P=0.4-0.7) although a greater separation between means was seen on delayed images (0.73 vs. 0.95).

CONCLUSION

HMR analysis using a suitable cut-off is more accurate than visual rating. Accuracy is similar for all methods, but freehand regions are more variable and 6 cm circles easiest to place. We recommend calculating HMR using a 6 cm circular cardiac region of interest on delayed images.

Diagnostic Criteria for Dementia with Lewy Bodies: Updates and Future Directions

The aim of this article is to describe the 2017 revised consensus criteria for the clinical diagnosis of dementia with Lewy bodies (DLB) with future directions for the diagnostic criteria. The criteria for the clinical diagnosis of probable and possible DLB were first published as the first consensus report in 1996 and were revised in the third consensus report in 2005. After discussion at the International DLB Conference in Fort Lauderdale, Florida, USA, in 2015, the International DLB Consortium published the fourth consensus report including the revised consensus criteria in 2017. The 2017 revised criteria clearly distinguish between clinical features and diagnostic biomarkers. Significant new information about previously reported aspects of DLB has been incorporated, with increased diagnostic weighting given to rapid eye movement (REM) sleep behavior disorder (RBD) and iodine-123-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. Future directions include the development of the criteria for early diagnosis (prodromal DLB) and the establishment of new biomarkers that directly indicate Lewy-related pathology, including α-synuclein imaging, biopsies of peripheral tissues (skin, etc.) for the demonstration of α-synuclein deposition, and biochemical markers (cerebrospinal fluid/blood), as well as the pathological evaluation of the sensitivity and specificity of the 2017 revised diagnostic criteria. In conclusion, the revised consensus criteria for the clinical diagnosis of DLB were reported with the incorporation of new information about DLB in 2017. Future directions include the development of the criteria for early diagnosis and the establishment of biomarkers directly indicative of Lewy-related pathology.

123I-MIBG scintigraphy utility and cut-off value in a clinically representative dementia cohort

OBJECTIVE

To determine the utility of ¹²³I-metaiodobenzylguanidine cardiac scintigraphy (MIBG), and optimum heart: mediastinum ratio (HMR) for differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) in a clinically representative population, comparing findings with those of ¹²³I-2β -carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (FP-CIT) SPECT.

METHODS

We recruited subjects with probable DLB (n = 17) and probable AD (n = 16) from clinical services. Each participant underwent clinical examination, cardiac MIBG scintigraphy and FP-CIT SPECT. Diagnosis was made on the basis of clinical symptoms using validated criteria. Cardiac MIBG uptake was measured by the planar HMR, blind to clinical diagnosis, with values below a cut-off taken from a previous study (<2.2 at four hours) defining scans as abnormal. FP-CIT scans were blindly rated according to a visual rating scale.

RESULTS

MIBG had a sensitivity, specificity and overall accuracy of 71%, 81% and 76% for distinguishing DLB from AD. FP-CIT demonstrated a sensitivity, specificity and accuracy of 82%, 88% and 85%. Using a lower HMR cut-off to distinguish between abnormal and normal MIBG scans improved the accuracy of MIBG, raising specificity (100%) and overall accuracy (85%) without compromising sensitivity (71%). Neither prescription of potentially interfering medications, nor a history of myocardial infarction (MI), had a significant effect on HMR.

CONCLUSION

We found that MIBG did not demonstrate superior sensitivity and overall accuracy to FP-CIT. HMR cut-off influences biomarker utility, and clinical and Caucasian populations may require a lower cut-off than those reported elsewhere. Future MIBG studies should include clinically representative cohorts as neither medications nor previous MI appear to influence HMR.

Dementia with Lewy bodies: an update and outlook

Dementia with Lewy bodies (DLB) is an age-associated neurodegenerative disorder producing progressive cognitive decline that interferes with normal life and daily activities. Neuropathologically, DLB is characterised by the accumulation of aggregated α-synuclein protein in Lewy bodies and Lewy neurites, similar to Parkinson’s disease (PD). Extrapyramidal motor features characteristic of PD, are common in DLB patients, but are not essential for the clinical diagnosis of DLB. Since many PD patients develop dementia as disease progresses, there has been controversy about the separation of DLB from PD dementia (PDD) and consensus reports have put forward guidelines to assist clinicians in the identification and management of both syndromes. Here, we present basic concepts and definitions, based on our current understanding, that should guide the community to address open questions that will, hopefully, lead us towards improved diagnosis and novel therapeutic strategies for DLB and other synucleinopathies.