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

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.

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.

Nuclear medicine practice in Japan: a report of the ninth nationwide survey in 2022

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. The subcommittee sent questionnaires, including the number and category of examinations as well as the kind of the radiopharmaceuticals during the 30 days of June 2022 to all nuclear medicine institutes in Japan. The total numbers of them for the year 2022 were estimated depends on the 1-month data. A total of 1095 institutes responded to the survey, including 364 positron emission tomography (PET) centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1299 in total, with 2.5% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 83.8% and 35.5%, respectively. The number of single-photon tracer studies in 2022 was 1.11 million which means increase in 2.7% in 5 years. Bone scintigraphy was a leading examination (31.0%), followed by myocardial scintigraphy (27.1%) and cerebral perfusion study (23.8%) in order. The percentage of SPECT studies showed an increase from 63.5% in previous survey to 66.8% in this survey. PET centers have also increased from 389 to 412, as compared with the previous one. One hundred and twenty-two PET centers have installed one or two in-house cyclotrons. Increasing trends of the PET studies were observed from 1992 to 2017, the trend changed and PET studies showed 1.5% decrease in 5 years. 18F-FDG accounted for 98.6% (610,497 examinations). PET examinations using 11C-methionine, 13N-NH3 and 11C-PIB have decreased, with 1624, 2146 and 525 examinations, respectively in 2022. The total number of nuclear medicine examination was eventually increased by 1.0%. Therapies for pheochromocytoma or paraganglioma (PPGL) with 131I-MIBG and for neuroendocrine tumor with 177Lu-DOTA-TATE were newly started, however, a total number of targeted radionuclide therapy was decreased by 17.7% because 131I-radioiodine and 223Ra targeted therapies were decreased and supply of some radioisotopes was discontinued. 131I-radioiodine targeted therapy showed a decrease in 5 years (- 15.9%), including 4099 patients for thyroid cancer. The number of out-patient thyroid bed ablation therapy with 1110 MBq of 131I was also decreased to 1015 per year. The number of admission rooms specialized for radionuclide targeted therapy increased from 157 to 160. The number of 223Ra targeted therapies for castration-resistant metastatic prostate cancer (mCRPC) was 1041 patients. This survey was performed during COVID-19 pandemic, however, total number of nuclear medicine examinations was almost same as previous survey (+ 1.0%). Radionuclide therapies with 131I-MIBG and 177Lu-DOTA-TATE were newly started, and new radionuclide therapy will be available in future, therefore, the development of radionuclide therapy will be continued. We are convinced that this survey report is useful in understanding the current status of the nuclear medicine practice in Japan, and in devising the new strategy to strengthen a role of nuclear medicine.

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.

Uniformity of cardiac 123I-MIBG uptake on SPECT images in older adults with normal cognition and patients with dementia

INTRODUCTION

Some studies report that assessing regional 123I-cardiac MIBG uptake can aid in the diagnosis of Lewy body disease, but others report heterogeneity in healthy controls. We aimed to evaluate regional cardiac MIBG uptake patterns in healthy older adults and patients with dementia.

METHODS

31 older adults with normal cognition, 15 Alzheimer's disease (AD), and 17 Dementia with Lewy bodies (DLB) patients were recruited. 5 individuals had previous myocardial infarction. Participants with sufficient cardiac uptake for regional SPECT analysis (29/31 controls, 15/15 AD, 5/17 DLB) had relative uptake pattern recorded. Controls were assessed for risk of future cardiovascular events using QRISK2, a validated online tool.

RESULTS

In controls uptake was reduced in the inferior wall (85%), apex (23%), septum (15%), and lateral wall (8%). AD and DLB showed similar patterns to controls. Lung or liver interference was present in 61% of cases. Myocardial infarction cases showed regional reductions in uptake, but normal/borderline planar uptake. In controls, there was no relationship between cardiovascular risk score and uptake pattern.

CONCLUSIONS

Significant variability of regional cardiac 123I-MIBG uptake is common in cases with normal planar cardiac uptake. Heterogeneity of regional uptake appears non-specific and unlikely to aid in the diagnosis of Lewy body disease.

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.

Diagnostic accuracy of DAT-SPECT and MIBG scintigraphy for dementia with Lewy bodies: an updated systematic review and Bayesian latent class model meta-analysis

PURPOSE

Imperfect clinical reference standards can preclude accurately estimating the diagnostic accuracy of DAT-SPECT and MIBG myocardial scintigraphy for diagnosing DLB. To investigate the validity of unadjusted accuracy, we updated our previous meta-analysis.

METHODS

Literature search was updated to March 18, 2018. We also examined published systematic review reports. Two investigators extracted data and rated study validity using the QUADAS-2 tool. We performed a Bayesian latent class model meta-analysis accounting for imperfect reference standards.

RESULTS

We evaluated 27 studies including 2236 patients. With the exception of two DAT-SPECT studies that involved postmortem neuropathological verification, studies were susceptible to bias from imperfect reference standards. Compared with the unadjusted accuracy estimates, the adjusted sensitivity values were similar, whereas the adjusted specificity values were generally lower for detecting α-synuclein pathology in the brain. The adjusted summary sensitivity and specificity were 0.86 (95% credible interval [CrI], 0.76-0.95) and 0.81 (CrI, 0.70-0.92), and 0.93 (CrI, 0.74-1.00) and 0.75 (CI, 0.47-0.94) for visual and semi-quantitative assessments of DAT-SPECT, respectively; 0.92 (CrI, 0.81-0.99) and 0.80 (CrI, 0.67-0.93), and 0.87 (CrI, 0.74-0.98) and 0.80 (CrI, 0.69-0.93), for delayed- and early-phase scans of MIBG scintigraphy, respectively. When diagnosing the typical clinical syndrome, the adjusted accuracy values were similar to the unadjusted estimates. The adjusted sensitivity and specificity were 0.89 (CrI, 0.75-0.98) and 0.87 (CrI, 0.72-0.97), and 0.97 (CrI, 0.78-1.0) and 0.70 (CrI, 0.43-0.92) for visual and semi-quantitative assessments of DAT-SPECT, respectively; and 0.93 (CrI, 0.81-0.98) and 0.90 (CrI, 0.73-0.97), and 0.85 (CrI, 0.66-0.96) and 0.96 (95% CI, 0.83-1.0) for delayed- and early-phase scans of MIBG scintigraphy, respectively.

CONCLUSIONS

In our adjusted analyses, both imaging biomarkers had high diagnostic accuracy for detecting the hallmark pathology in the brain and for diagnosing the typical clinical syndrome.

Nuclear medicine practice in Japan: a report of the eighth nationwide survey in 2017

OBJECTIVE

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years.

METHODS

The subcommittee sent questionnaires, including the number and category of examinations as well as the kind and dose of the radiopharmaceuticals during the 30 days of June 2017, to all nuclear medicine institutes. The total numbers for the year 2017 were then estimated.

RESULTS

A total of 1132 institutes responded to the survey, including 351 PET centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1332 in total, with 7.0% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 88.2 and 23.6%, respectively. The number of single-photon tracer studies in 2017 was 1.08 million which means a decrease in 5.7% in 5 years and 23.6% in 10 years. All but neurotransmitter system, sentinel lymph node, and liver scintigraphy decreased. Bone scintigraphy was a leading examination (32.3%), followed by myocardial scintigraphy (24.1%) and cerebral perfusion study (18.0%) in order. SPECT studies showed an increase from 47.2% to 63.5%. PET centers have also increased from 295 to 389, as compared to the last survey. The 112 PET centers have installed one or two in-house cyclotrons. PET studies showed 24.5% increase in 5 years, with oncology accounting for 88.9%. ¹⁸F-FDG accounted for 98.2% (630,570 examinations). PET examinations using ¹¹C-methionine have decreased, with 2440 examinations in 2017. PET examinations using ¹³N-NH₃ have been increasing, with 2363 examinations in 2017. The number of PET studies using ¹¹C-PIB was 904. ¹³¹I-radioiodine targeted therapies showed an increase in 5 years (23.1%), including 4487 patients for thyroid cancer. Out-patient thyroid bed ablation therapy with 1,110 MBq of ¹³¹I accounted for 36.6% of cancer patients. The number of admission rooms increased from 135 to 157 in 5 years. The number of ²²³Ra targeted therapies for castration-resistant metastatic prostate cancer was 1194 patients.

CONCLUSIONS

Single-photon examinations showed a continuous tendency toward a decline in the survey. In contrast, the number of hybrid SPECT/CT scanner examinations has increased. PET/CT study and radionuclide targeted therapy have steadily increased.

Dementia with Lewy bodies: Challenges in the diagnosis and management

OBJECTIVE

Dementia with Lewy bodies is the second most common form of neurodegenerative dementia in older age yet is often under-recognised and misdiagnosed. This review aims to provide an overview of the clinical features of dementia with Lewy bodies, discussing the frequent challenges clinicians experience in diagnosing dementia with Lewy bodies, and outlines a practical approach to the clinical management, particularly in the Australian setting.

METHODS

This paper is a narrative review and a semi-structured database (PubMed and MEDLINE) search strategy was implemented. Articles were screened and clinically relevant studies were selected for inclusion.

RESULTS

Dementia with Lewy bodies is clinically characterised by complex visual hallucinations, spontaneous motor parkinsonism, prominent cognitive fluctuations and rapid eye movement sleep behaviour disorder. Neuropsychiatric features and autonomic dysfunction are also common. The new diagnostic criteria and specific diagnostic biomarkers help to improve detection rates and diagnostic accuracy, as well as guide appropriate management. Clinical management of dementia with Lewy bodies is challenging and requires an individualised multidisciplinary approach with specialist input.

CONCLUSION

Dementia with Lewy bodies is a common form of dementia. It often presents as a diagnostic challenge to clinicians, particularly at early stages of disease, and in patients with mixed neuropathological changes, which occur in over 50% of people with dementia with Lewy bodies. Prompt diagnosis and comprehensive treatment strategies are important in improving patients' care.

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.

Does applying resolution recovery to normal databases confer an advantage over conventional 3D-stereotactic surface projection techniques?

We evaluated a novel normal database (NDB) generated using single photon emission computed tomography (SPECT) data obtained from healthy brains by using a SPECT/CT system, analyzed using a resolution recovery (RR) technique applied to the three-dimensional stereotactic surface projection (3D-SSP) technique. We used a three-dimensional ordered subset expectation maximization method (3D-OSEM) with applied scatter correction (SC), attenuation correction, and RR to reconstruct the data. We verified the accuracy of the novel NDB's values (Z, extent, and error scores), and compared the novel NDB to the 3D-SSP technique by using simulated misery perfusion-related patient data from a conventional NDB. In addition, Z, extent, and error scores at the precuneus, cuneus, and posterior cingulate were compared under different reconstruction conditions by using the patient data. In the simulation, Z scores decreased when using the novel NDB corrected using computed tomography-based attenuation correction (CTAC), SC, and RR. The extent scores of the posterior cingulate increased using the novel NDB, relative to the other NDBs. The error score with the novel NDB without RR decreased by 15% compared to that of the conventional NDB. Z scores generated from patient data decreased in the novel NDB with RR. The extent scores tended to decrease in the novel NDB with RR. The extent scores in the novel NDB with RR improved at the posterior cingulate, compared to the scores with the other NDBs. However, applying RR to the novel NDB conferred no advantage because the cut-off of the current Z score must be reconsidered when using the additive RR technique.

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.

Early differential diagnosis between Alzheimer's disease and dementia with Lewy bodies: Comparison between (18)F-FDG PET and (123)I-IMP SPECT

Both (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and (123)I-iodoamphetamine (IMP) single-photon emission computed tomography (SPECT) have been used for the differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Less information is available, however, regarding the differential diagnosis of mild cognitive impairment (MCI) due to AD and MCI due to DLB. We examined nine AD patients (AD group), nine DLB patients (DLB group), eight MCI due to AD patients (MCI-AD group), and nine MCI due to DLB patients (MCI-DLB group) with FDG PET and IMP SPECT using a well-characterized normal database and a stereotactic extraction estimation method. In the AD and DLB groups, receiver operating characteristic (ROC) analysis in the occipital regions showed significant accuracy of both FDG PET and IMP SPECT for the differential diagnosis. In the MCI-AD and MCI-DLB groups, ROC analysis showed significant accuracy of only FDG PET for the differential diagnosis. Both FDG PET and IMP SPECT would be useful for the differential diagnosis between AD and DLB. For the differential diagnosis of MCI-AD versus MCI-DLB, FDG PET would be more useful than IMP SPECT.

Quantitative correlation between cardiac MIBG uptake and remaining axons in the cardiac sympathetic nerve in Lewy body disease

OBJECTIVES

Reduced cardiac meta-iodobenzylguanidine (MIBG) uptake and loss of cardiac sympathetic axons, as its possible anatomical substrate, were both recognised in Lewy body disease (LBD), while their direct correlation has so far remained speculative. Increasing availability of autopsy-confirmed cases of LBD prompted us to quantify residual cardiac sympathetic axons to establish their relationship to cardiac MIBG uptake.

METHODS

We collected cardiac tissue samples from 23 patients with autopsy-confirmed LBD and two non-LBD control patients who underwent (123)I-MIBG cardiac scintigraphy in life. Samples of the left ventricular anterior wall were stained with anti-tyrosine hydroxylase (TH) and anti-neurofilament (NF) antibodies as markers of cardiac nerve axons. We quantified the immunolabelled areas and assessed their correlation to standardised heart to mediastinum (H/M) ratios of (123)I-MIBG cardiac scintigraphy.

RESULTS

Cardiac MIBG uptake in the early and delayed phases was reduced in 90.9% and 95.7% of patients with LBD, respectively. The area of TH-immunoreactive axons correlated significantly with the H/M ratio in the early (p=0.036) as well as in the delayed (p=0.018) phases. The area of NF-immunoreactive axons also correlated with the H/M ratio in the early (p=0.003) as well as in the delayed (p=0.001) phases.

CONCLUSIONS

Tight quantitative correlation between cardiac (123)I-MIBG uptake and corresponding loss of sympathetic axons in LBD, as established for the first time by this study, provides a scientific basis to confirm the reliability of MIBG cardiac scintigraphy as a powerful clinical tool to detect loss of these axons as a biomarker for the presence of Lewy body disease.

Molecular imaging biomarkers for dementia with Lewy bodies: an update

BACKGROUND

Dementia with Lewy body (DLB) is considered to be the second most common form of neurodegenerative disorders after Alzheimer's disease (AD), affecting as many as 100,000 people in the UK and up to 1.3 million in the USA. However, nearly half of patients with DLB remain undiagnosed thus depriving many of them from an early and adequate treatment of their distressing symptoms. Accurate and early diagnosis of DLB is important for both patients and their caregivers, since the neuropsychiatric symptoms require specific management.

METHODS

In the current study, we review the most recent developments in the field of molecular nuclear imaging to diagnose DLB.

RESULTS

The review addresses, the neurotransmitter based (dopaminergic, cholinergic, and glutamatergic) nuclear imaging techniques, role of the autonomic dysfunction and its visualization in DLB with myocardial sympathetic imaging and vesicular catecholamine uptake, as well as the use of amyloid polypeptides and glial markers as molecular imaging probes in the clinical diagnosis of DLB.

CONCLUSIONS

Most of the above nuclear imaging methods are restricted to highly specialized clinical centers, and thus not applicable to a large number of patients requiring dementia (e.g. DLB) diagnosis in routine clinical setting. Validating them against more readily accessible peripheral biomarkers, e.g. CSF and blood biomarkers linked to the DLB process, may facilitate their use in wider clinical settings.

Consistent abnormalities in metabolic network activity in idiopathic rapid eye movement sleep behaviour disorder

Rapid eye movement sleep behaviour disorder has been evaluated using Parkinson's disease-related metabolic network. It is unknown whether this disorder is itself associated with a unique metabolic network. 18F-fluorodeoxyglucose positron emission tomography was performed in 21 patients (age 65.0±5.6 years) with idiopathic rapid eye movement sleep behaviour disorder and 21 age/gender-matched healthy control subjects (age 62.5±7.5 years) to identify a disease-related pattern and examine its evolution in 21 hemi-parkinsonian patients (age 62.6±5.0 years) and 16 moderate parkinsonian patients (age 56.9±12.2 years). We identified a rapid eye movement sleep behaviour disorder-related metabolic network characterized by increased activity in pons, thalamus, medial frontal and sensorimotor areas, hippocampus, supramarginal and inferior temporal gyri, and posterior cerebellum, with decreased activity in occipital and superior temporal regions. Compared to the healthy control subjects, network expressions were elevated (P<0.0001) in the patients with this disorder and in the parkinsonian cohorts but decreased with disease progression. Parkinson's disease-related network activity was also elevated (P<0.0001) in the patients with rapid eye movement sleep behaviour disorder but lower than in the hemi-parkinsonian cohort. Abnormal metabolic networks may provide markers of idiopathic rapid eye movement sleep behaviour disorder to identify those at higher risk to develop neurodegenerative parkinsonism.