Impact of [11C]methionine PET with Bayesian penalized likelihood reconstruction on glioma grades based on new WHO 2021 classification

OBJECTIVE

The uptake of [11C]methionine in positron emission tomography (PET) imaging overlapped in earlier images of tumors. Bayesian penalized likelihood (BPL) reconstruction increases the quantitative values of tumors compared with conventional ordered subset-expectation maximization (OSEM). The present study aimed to grade glioma malignancy based on the new WHO 2021 classification using [11C]methionine PET images reconstructed using BPL.

METHODS

We categorized 32 gliomas in 28 patients as grades 2/3 (n = 15) and 4 (n = 17) based on the WHO 2021 classification. All [11C]methionine images were reconstructed using OSEM + time-of-flight (TOF) and BPL + TOF (β = 200). Maximum standardized uptake value (SUVmax) and tumor-to-normal tissue ratio (T/Nmax) were measured at each lesion.

RESULTS

The mean SUVmax was 4.65 and 4.93 in grade 2/3 and 6.38 and 7.11 in grade 4, and the mean T/Nmax was 7.08 and 7.22 in grade 2/3 and 9.30 and 10.19 in grade 4 for OSEM and BPL, respectively. The BPL significantly increased these values in grade 4 gliomas. The area under the receiver operator characteristic (ROC) curve (AUC) for SUVmax was the highest (0.792) using BPL.

CONCLUSIONS

The BPL increased mean SUVmax and mean T/Nmax in lesions with higher contrast such as grade 4 glioma. The discrimination power between grades 2/3 and 4 in SUVmax was also increased using [11C]methionine PET images reconstructed with BPL.

Phantom and clinical evaluation of the Bayesian penalised likelihood reconstruction algorithm Q.Clear without PSF correction in amyloid PET images

PURPOSE

Bayesian penalised likelihood (BPL) reconstruction, which incorporates point-spread-function (PSF) correction, provides higher signal-to-noise ratios and more accurate quantitation than conventional ordered subset expectation maximization (OSEM) reconstruction. However, applying PSF correction to brain PET imaging is controversial due to Gibbs artefacts that manifest as unpredicted cortical uptake enhancement. The present study aimed to validate whether BPL without PSF would be useful for amyloid PET imaging.

METHODS

Images were acquired from Hoffman 3D brain and cylindrical phantoms for phantom study and 71 patients administered with [18F]flutemetamol in clinical study using a Discovery MI. All images were reconstructed using OSEM, BPL with PSF correction, and BPL without PSF correction. Count profile, %contrast, recovery coefficients (RCs), and image noise were calculated from the images acquired from the phantoms. Amyloid β deposition in patients was visually assessed by two physicians and quantified based on the standardised uptake value ratio (SUVR).

RESULTS

The overestimated radioactivity in profile curves was eliminated using BPL without PSF correction. The %contrast and image noise decreased with increasing β values in phantom images. Image quality and RCs were better using BPL with, than without PSF correction or OSEM. An optimal β value of 600 was determined for BPL without PSF correction. Visual evaluation almost agreed perfectly (κ = 0.91-0.97), without depending on reconstruction methods. Composite SUVRs did not significantly differ between reconstruction methods.

CONCLUSION

Gibbs artefacts disappeared from phantom images using the BPL without PSF correction. Visual and quantitative evaluation of [18F]flutemetamol imaging was independent of the reconstruction method. The BPL without PSF correction could be the standard reconstruction method for amyloid PET imaging, despite being qualitatively inferior to BPL with PSF correction for [18F]flutemetamol amyloid PET imaging.

Pitfalls of Amyloid-Beta PET: Comparisons With 18 F-MK-6240 and 18 F-THK5351 PET

ABSTRACT

We present 3 patients as pitfalls of amyloid-beta (Aβ) PET, who underwent 11 C-PiB (Aβ), 18 F-MK-6240 (Alzheimer disease [AD]-tau), and 18 F-THK5351 (astrogliosis) PET examinations. Despite negligible or tiny Aβ pathology, patients 1 and 2 were diagnosed with AD as the cause of symptoms. Despite widespread Aβ pathology, patient 3 was not diagnosed with AD as the cause of symptoms. However, if we had only conducted Aβ PET, patients 1 and 2 might not have been diagnosed with AD, whereas patient 3 might have been diagnosed with AD. Hence, both Aβ and AD-tau assessments are necessary to relate clinical symptoms to AD pathology.

Clinical application of MAO-B PET using 18F-THK5351 in neurological disorders

Monoamine oxidase B (MAO-B) is an enzyme localized to the outer mitochondrial membrane and highly concentrated in astrocytes. Temporal changes in regional MAO-B levels can be used as an index of astrocytic proliferation, known as activated astrocytes or astrogliosis. MAO-B is a marker to evaluate the degree of astrogliosis. Therefore, MAO-B positron emission tomography (PET) is a powerful imaging technique for visualizing and quantifying ongoing astrogliosis through the estimate of regional MAO-B levels. Each neurodegenerative disorder generally has a characteristic distribution pattern of astrogliosis secondary to neuronal loss and pathological protein aggregation. Therefore, by imaging astrogliosis, MAO-B PET can be used as a neurodegeneration marker for identifying degenerative lesions. Any inflammation in the brain usually accompanies astrogliosis starting from an acute phase to a chronic phase. Therefore, by imaging astrogliosis, MAO-B PET can be used as a neuroinflammation marker for identifying inflammatory lesions. MAO-B levels are high in gliomas originating from astrocytes but low in lymphoid tumors. Therefore, MAO-B PET can be used as a brain tumor marker for identifying astrocytic gliomas by imaging MAO-B levels and distinguishing between astrocytic and lymphoid tumors. This review summarizes the clinical application of MAO-B PET using 18F-THK5351 as markers for neurodegeneration, neuroinflammation, and brain tumors in neurological disorders. Because we assume that MAO-B PET is clinically applied to an individual patient, we focus on visual inspection of MAO-B images at the individual patient level. Geriatr Gerontol Int 2024; 24: 31-43.

Ventral Variant Posterior Cortical Atrophy with Occipito-temporal Accumulation of Tau Proteins/Astrocyte Gliosis

A 73-year-old woman with posterior cortical atrophy (PCA) presented with progressive apperceptive visual agnosia, alexia, agraphia, ventral simultanagnosia, prosopagnosia, and allocentric (stimulus-centered) left-sided hemispatial neglect. All of these symptoms were attributed to damage to the bilateral occipito-temporal cortices, consistent with ventral variant PCA. While the Pittsburgh compound B uptake was extensively distributed throughout the occipito-parietal (dorsal) and occipito-temporal (ventral) areas, the THK5351 (ligand binding to tau aggregates/astrocyte gliosis) accumulation was limited to the ventral area. These findings suggest that local accumulation of tau proteins and/or astrocyte gliosis over the occipito-temporal cortices can result in ventral variant PCA.

Diagnostic performance of the cingulate island sign ratio for differentiating dementia with Lewy bodies from Alzheimer's disease changes depending on the mini-mental state examination score

BACKGROUND

The cingulate island sign (CIS) ratio is a diagnostic adjunct for differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD). A recent study showed that the CIS ratio in DLB changed depending on the Mini-Mental State Examination (MMSE) score. We aimed to evaluate whether the diagnostic performance (sensitivity and specificity) of the CIS ratio for differentiating DLB from AD changes depending on the MMSE score.

METHODS

Twenty-two patients with DLB and 26 amyloid-positive patients with AD, who underwent 18F-FDG PET and completed an MMSE examination, were classified into three groups according to MMSE scores: Group A (MMSE >24), Group B (20 ≤ MMSE ≤24), and Group C (MMSE <20). In each group, we compared the CIS ratio between patients with DLB and AD and conducted receiver operating characteristic (ROC) curve analysis to calculate the sensitivity and specificity.

RESULTS

Within Group B, the CIS ratio in DLB was significantly higher than that in AD (p = 0.0005), but not within Groups A (p = 0.5117) and C (p = 0.8671). ROC curve analyses showed that the sensitivities and specificities of the CIS ratio for differentiating DLB from AD were 66.7% and 77.8% in Group A, 91.7% and 100.0% in Group B, and 75.0% and 66.7% in Group C, respectively.

CONCLUSIONS

The present study suggests that the diagnostic performance of the CIS ratio for differentiating DLB from AD changes depending on the MMSE score, with higher sensitivity and specificity at MMSE scores of 20-24.

Detailed Assessment of 18F-THK5351 Distribution Pattern in the Midbrain: Comparison With Progressive Supranuclear Palsy and Corticobasal Syndrome

BACKGROUND

18F-THK5351 PET is used to image ongoing astrogliosis by estimating monoamine oxidase B levels. 18F-THK5351 preferentially accumulates around the substantia nigra (SN) and periaqueductal gray (PG) in the midbrain under healthy conditions and exhibits a "trimodal pattern." In progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), the midbrain 18F-THK5351 uptake can be increased by astrogliosis, collapsing the "trimodal pattern." We aimed to elucidate cases in which the "trimodal pattern" collapses in PSP and CBS.

PATIENTS AND METHODS

Participants in the PSP (n = 11), CBS (n = 17), Alzheimer disease (n = 11), and healthy control (n = 8) groups underwent 18F-THK5351 PET. Volumes of interest (VOIs) were placed on the SN, PG, and their midpoints. The midbrain uptake ratio (MUR) was calculated to assess the trimodal pattern as follows: MUR = (VOI value on the midpoint)/(VOI value on the SN and PG). Approximately, the trimodal pattern can be identified at MUR <1 but not at MUR >1.

RESULTS

Compared with the healthy control group, MUR significantly increased in the PSP (P < 0.01) and CBS (P < 0.01) groups, but was unchanged in the Alzheimer disease group (P = 0.10). In the PSP group, all patients, including 2 with mild symptoms and a short disease duration, showed MUR >1. In the CBS group, MUR varied widely.

CONCLUSIONS

In PSP, the trimodal pattern can collapse even in the early phase when symptoms are mild. In CBS, the trimodal pattern may or may not collapse depending on the underlying pathology.

Clinical Application of 18F-THK5351 PET to Identify Inflammatory Lesions Through Imaging Astrogliosis in a Case of Cytomegalovirus Ventriculoencephalitis

ABSTRACT

18F-THK5351 PET is used to estimate the degree of astrogliosis. Because inflammatory lesions usually accompany astrogliosis, 18F-THK5351 PET is potentially worthy of clinical application in inflammatory disorders. Here, we report a case of cytomegalovirus ventriculoencephalitis in an immunocompromised 75-year-old woman who underwent 18F-THK5351 PET and conventional neuroimaging modalities, including 11C-methionine, 18F-FDG, and MRI. 18F-THK5351 PET was clearly superior to the other modalities in identifying inflammatory lesions and can therefore be a useful marker for identifying inflammatory lesions through imaging astrogliosis. This feature of 18F-THK5351 may contribute to the early diagnosis of cytomegalovirus ventriculoencephalitis.

High sensitivity of asymmetric 18F-THK5351 PET abnormality in patients with corticobasal syndrome

Corticobasal syndrome (CBS) is characterized by symptoms related to the asymmetric involvement of the cerebral cortex and basal ganglia. However, early detection of asymmetric imaging abnormalities can be challenging. Previous studies reported asymmetric ¹⁸F-THK5351 PET abnormalities in CBS patients, but the sensitivity for detecting such abnormalities in larger patient samples, including early-stage cases, remains unclear. Patients clinically diagnosed with CBS were recruited. All patients displayed asymmetric symptoms in the cerebral cortex and basal ganglia. Asymmetric THK5351 PET abnormalities were determined through visual assessment. Brain MRI, perfusion SPECT, and dopamine transporter (DAT) SPECT results were retrospectively reviewed. The 15 patients had a median age of 72 years (59-86 years) and a disease duration of 2 years (0.5-7 years). Four patients met the probable and 11 met the possible CBS criteria according to Armstrong criteria at the time of PET examination. All patients, including early-stage cases, exhibited asymmetric tracer uptake contralateral to their symptom-dominant side in the cerebral cortex/subcortical white matter and striatum (100%). The sensitivity for detecting asymmetric imaging abnormalities contralateral to the symptom-dominant side was 86.7% for brain MRI, 81.8% for perfusion SPECT, and 90% for DAT SPECT. White matter volume reduction was observed in the subcortical region of the precentral gyrus with increased THK5351 uptake, occurring significantly more frequently than gray matter volume reduction. THK5351 PET may be a sensitive imaging technique for detecting asymmetric CBS pathologies, including those in early stages.

Combined Exercise and Education Program: Effect of Smaller Group Size and Longer Duration on Physical Function and Social Engagement among Community-Dwelling Older Adults

Background

Exercise, education, and social engagement are critical interventions for older adults for a healthy life expectancy and to improve their physical function.

Objective

To conduct a combined exercise and education (CEE) program for improved social engagement and physical function of older adults.

Design

Based on a short-term program we conducted in our previous study, in this study, the program was conducted for half the number of participants of the earlier study but for a longer duration.

Setting

A community of older adults in Ami, Japan, was the setting of the study.

Participants

23 healthy older adults >65 years living in the community were the participants in the study.

Interventions

Five 80-minute sessions conducted once in two weeks comprised 60-min exercise instruction and 20-min educational lectures per session on health. We examined the improvement in physical and social engagement before and after participation. Physical function and health-related questionnaire data were collected before and after the program.

Results

Data analysis from 15 participants showed improved physical performance but no effect on social engagement.

Conclusions

A higher program frequency, rather than program duration, may be vital to improving exercise performance and social engagement and maximizing the effects of high group cohesion in small groups. Further studies are needed to develop more effective interventions to extend healthy life expectancy.

18 F-THK5351 PET Can Evaluate Tumor Extension in Intravascular Large B-Cell Lymphoma : Comparison With 11C-Methionine PET and 18F-FDG PET

ABSTRACT

A 79-year-old man presenting with gait disturbance and cognitive decline was diagnosed with intravascular large B-cell lymphoma (IVLBCL) by random skin biopsy. Some IVLBCL lesions were identified by PET examinations using 11 C-methionine, 18 F-FDG, and 18 F-THK5351. 11 C-methionine and 18 F-FDG uptake, which likely reflects the presence of the lymphoma cells themselves, increased clearly in the left putamen but weakly in the left deep white matter. 18 F-THK5351 uptake increased in all lesions, likely reflecting perivascular astrogliosis caused by IVLBCL. Hence, 18 F-THK5351 PET can evaluate tumor extension in IVLBCL lesions where 11 C-methionine and 18 F-FDG PET may fail in its visualization.

CSF P-Tau181 and Other Biomarkers in Patients With Neuronal Intranuclear Inclusion Disease

BACKGROUND AND OBJECTIVES

CSF tau phosphorylated at threonine 181 (p-tau181) is a widely used biomarker for Alzheimer disease (AD) and has recently been regarded to reflect β-amyloid and/or p-tau deposition in the AD brain. Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease characterized by intranuclear inclusions in neurons, glial cells, and other somatic cells. Symptoms include dementia, neuropathy, and others. CSF biomarkers were not reported. The objective of this study was to investigate whether CSF biomarkers including p-tau181 are altered in patients with NIID.

METHODS

This was a retrospective observational study. CSF concentrations of p-tau181, total tau, amyloid-beta 1-42 (Aβ42), monoamine metabolites homovanillic acid (HVA), and 5-hydroxyindole acetic acid (5-HIAA) were compared between 12 patients with NIID, 120 patients with Alzheimer clinical syndrome biologically confirmed based on CSF biomarker profiles, and patients clinically diagnosed with other neurocognitive disorders (dementia with Lewy bodies [DLB], 24; frontotemporal dementia [FTD], 13; progressive supranuclear palsy [PSP], 21; and corticobasal syndrome [CBS], 13). Amyloid PET using Pittsburgh compound B (PiB) was performed in 6 patients with NIID.

RESULTS

The mean age of patients with NIID, AD, DLB, FTD, PSP, and CBS was 71.3, 74.6, 76.8, 70.2, 75.5, and 71.9 years, respectively. CSF p-tau181 was significantly higher in NIID (72.7 ± 24.8 pg/mL) compared with DLB, PSP, and CBS and was comparable between NIID and AD. CSF p-tau181 was above the cutoff value (50.0 pg/mL) in 11 of 12 patients with NIID (91.7%). Within these patients, only 2 patients showed decreased CSF Aβ42, and these patients showed negative or mild local accumulation in PiB PET, respectively. PiB PET scans were negative in the remaining 4 patients tested. The proportion of patients with increased CSF p-tau181 and normal Aβ42 (A-T+) was significantly higher in NIID (75%) compared with DLB, PSP, and CBS (4.2%, 4.8%, and 7.7%, respectively). CSF HVA and 5-HIAA concentrations were significantly higher in patients with NIID compared with disease controls.

DISCUSSION

CSF p-tau181 was increased in patients with NIID without amyloid accumulation. Although the deposition of p-tau has not been reported in NIID brains, the molecular mechanism of tau phosphorylation or secretion of p-tau may be altered in NIID.

Possibility of Enlargement in Left Medial Temporal Areas Against Cerebral Amyloid Deposition Observed During Preclinical Stage

Neurodegenerative changes in the preclinical stage of Alzheimer’s disease (AD) have recently been the focus of attention because they may present a range of treatment opportunities. A total of 134 elderly volunteers who lived in a local community were investigated and grouped into preclinical and mild cognitive impairment stages according to the Clinical Dementia Rating test; we also estimated amyloid deposition in the brain using positron emission tomography (PET). A significant interaction between clinical stage and amyloid PET positivity on cerebral atrophy was observed in the bilateral parietal lobe, parahippocampal gyri, hippocampus, fusiform gyrus, and right superior and middle temporal gyri, as previously reported. Early AD-specific voxel of interest (VOI) analysis was also applied and averaged Z-scores in the right, left, bilateral, and right minus left medial temporal early AD specific area were computed. We defined these averaged Z-scores in the right, left, bilateral, and right minus left early AD specific VOI in medial temporal area as R-MedT-Atrophy-score, L-MedT-Atrophy-score, Bil-MedT-Atrophy-score, and R_L-MedT-Atrophy-score, respectively. It revealed that the R_L-MedT-Atrophy-scores were significantly larger in the amyloid-positive than in the amyloid-negative cognitively normal (CN) elderly group, that is, the right medial temporal areas were smaller than left in amyloid positive CN group and these left-right differences were significantly larger in amyloid positive than amyloid negative CN elderly group. The L-MedT-Atrophy-score was slightly larger (p = 0.073), that is, the left medial temporal area was smaller in the amyloid-negative CN group than in the amyloid-positive CN group. Conclusively, the left medial temporal area could be larger in CN participants with amyloid deposition than in those without amyloid deposition. The area under the receiver operating characteristic curve for differentiating amyloid positivity among CN participants using the R_L-MedT-Atrophy-scores was 0.73; the sensitivity and specificity were 0.828 and 0.606, respectively. Although not significant, a negative correlation was observed between the composite cerebral standardized uptake value ratio in amyloid PET images and L-MedT-Atrophy-score in CN group. The left medial temporal volume might become enlarged because of compensatory effects against AD pathology occurring at the beginning of the amyloid deposition.

Determination of optimal regularization factor in Bayesian penalized likelihood reconstruction of brain PET images using [18 F]FDG and [11 C]PiB

PURPOSE

The Bayesian penalized likelihood (BPL) reconstruction algorithm, Q.Clear, can achieve a higher signal-to-noise ratio on images and more accurate quantitation than ordered subset-expectation maximization (OSEM). The reconstruction parameter (β) in BPL requires optimization according to the radiopharmaceutical tracer. The present study aimed to define the optimal β value in BPL required to diagnose Alzheimer disease from brain PET images acquired using ¹⁸ F-fluoro-2-deoxy-D-glucose ([¹⁸ F]FDG) and ¹¹ C-labeled Pittsburg compound B ([¹¹ C]PiB).

METHODS

Images generated from Hoffman 3D brain and cylindrical phantoms were acquired using a Discovery PET/CT 710 and reconstructed using OSEM + time-of-flight (TOF) under clinical conditions and BPL + TOF (β = 20-1,000). Contrast was calculated from images generated by the Hoffman 3D brain phantom, and noise and uniformity were calculated from those generated by the cylindrical phantom. Five cognitively healthy controls and five patients with Alzheimer disease were assessed using [¹⁸ F]FDG and [¹¹ C]PiB PET to validate the findings from the phantom study. The β values were restricted by the findings of the phantom study, then one certified nuclear medicine physician and two certified nuclear medicine technologists visually determined optimal β values by scoring the quality parameters of image contrast, image noise, cerebellar stability, and overall image quality of PET images from 1 (poor) to 5 (excellent).

RESULTS

The contrast in BPL satisfied the Japanese Society of Nuclear Medicine (JSNM) criterion of ≥ 55% and exceeded that of OSEM at ranges of β = 20-450 and 20-600 for [¹⁸ F]FDG and [¹¹ C]PiB, respectively. The image noise in BPL satisfied the JSNM criterion of ≤ 15% and was below that in OSEM when β = 150-1000 and 400-1,000 for [¹⁸ F]FDG and [¹¹ C]PiB, respectively. The phantom study restricted the ranges of β values to 100-300 and 300-500 for [¹⁸ F]FDG and [¹¹ C]PiB, respectively. The BPL scores for grey-white matter contrast and image noise, exceeded those of OSEM in [¹⁸ F]FDG and [¹¹ C]PiB images regardless of β values. Visual evaluation confirmed that the optimal β values were 200 and 450 for [¹⁸ F]FDG and [¹¹ C]PiB, respectively.

CONCLUSIONS

The BPL achieved better image contrast and less image noise than OSEM, while maintaining quantitative SUVR due to full convergence, more rigorous noise control and edge preservation. The optimal β values for [¹⁸ F]FDG and [¹¹ C]PiB brain PET were apparently 200 and 450, respectively. The present study provides useful information about how to determine optimal β values in BPL for brain PET imaging. This article is protected by copyright. All rights reserved.

A Novel Proposal for an Index for Regional Cerebral Perfusion Pressure – A Theoretical Approach Using Fluid Dynamics

Cerebral blood flow (CBF) / cerebral blood volume (CBV) ratio derived by [¹⁵O] H₂O/ CO₂ and CO positron emission tomography (PET) examination has been used as an index for cerebral perfusion pressure (CPP). CBF/CBV was demonstrated to be related mean arterial pressure (MAP) in baboons. However, this formula has not been confirmed to be proportionate to CPP. We have developed a new index for CPP using the Poiseuille equation based on a simple model. Our model suggests that CBF/CBV² is proportionate to CPP and that it is mathematically a more accurate index than CBF/CBV. This new index needs experimental validation in the future.

Adenosine A2A Receptor Occupancy by Caffeine After Coffee Intake in Parkinson's Disease

Background

Coffee intake can decrease the risk for Parkinson's disease (PD). Its beneficial effects are allegedly mediated by caffeine through adenosine A_2A receptor (A_2AR) antagonist action.

Objective

We aimed to calculate occupancy rates of striatal A_2ARs by caffeine after coffee intake in PD.

Methods

Five patients with PD underwent ¹¹C‐preladenant positron emission tomography scanning at baseline and after intake of coffee containing 129.5 mg (n = 3) or 259 mg (n = 2) of caffeine. Concurrently, serum caffeine levels were measured.

Results

The mean serum caffeine level (μg/mL) was 0.374 at baseline and increased to 4.48 and 8.92 by 129.5 and 259 mg of caffeine, respectively. The mean occupancy rates of striatal A_2ARs by 129.5 and 259 mg of caffeine were 54.2% and 65.1%, respectively.

Conclusions

A sufficient A_2AR occupancy can be obtained by drinking a cup of coffee, which is equivalent to approximately 100 mg of caffeine. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

18F-THK5351 PET Can Identify Core Lesions in Different Amyotrophic Lateral Sclerosis Phenotypes

ABSTRACT

Two patients with different amyotrophic lateral sclerosis (ALS) phenotypes underwent 18F-THK5351 PET to visualize lesions undergoing astrogliosis by measuring monoamine oxidase B activity. Patient 1 was a 57-year-old man with flail leg syndrome. Elevated uptake was observed inside the motor cortex, corresponding to the leg area in a cortical homunculus. Patient 2 was a 64-year-old man with ALS-frontotemporal dementia semantic variant. Elevated uptake was observed around the left anterior temporal lobe. Both core lesions were consistent with their respective neurological features. Hence, 18F-THK5351 PET is a useful technique to assess ALS pathophysiology by visualizing the core lesions.

Test-retest reproducibility of cerebral adenosine A2A receptor quantification using [11C]preladenant

OBJECTIVE

To evaluate the reproducibility of cerebral adenosine A_2A receptor (A_2AR) quantification using [¹¹C]preladenant ([¹¹C]PLN) and PET in a test-retest study.

METHODS

Eight healthy male volunteers were enrolled. Dynamic 90 min PET scans were performed twice at the same time of the day to avoid the effect of diurnal variation. Subjects refrained from caffeine from 12 h prior to scanning, and serum caffeine was measured before radioligand injection. Arterial blood was sampled repeatedly during scanning and the fraction of the parent compound in plasma was determined. Total distribution volume (V_T) was estimated using 1- and 2-tissue compartment models (1-TCM and 2-TCM, respectively) and Logan graphical analysis (Logan plot) (t* = 30 min). Plasma-free fraction (f_P) of [¹¹C]PLN was measured and used for correction of V_T values. Distribution volume ratio (DVR) was calculated from V_T of target and reference regions and obtained by noninvasive Logan graphical reference tissue model (LGAR) (t* = 30 min). Absolute test-retest variability (aTRV), and intra-class correlation coefficient (ICC) of V_T and DVR were calculated as indexes of repeatability. Correlation between DVR and serum concentration of caffeine (a nonselective A_2AR blocker) was analyzed by Pearson's correlation analysis.

RESULTS

Regional time-activity curves were well described by 2-TCM models. Estimation of V_T by 2-TCM produced some erroneous values; therefore, the more robust Logan plot was selected as the appropriate model. Global mean aTRV was 20% for V_T and 14% for V_T/f_P (ICC, 0.72 for V_T and 0.87 for V_T/f_P). Global mean aTRV of DVR was 13% for Logan plot and 10% for LGAR (ICC, 0.70 for Logan plot and 0.81 for LGAR). DVR estimates using LGAR and Logan plot were in good agreement (r² = 0.96). Coefficients of variation for V_T, V_T/f_P, DVR (Logan plot), and DVR (LGAR) were 47%, 47%, 27%, and 18%, respectively. Despite low serum caffeine levels, significant concentration-dependent effects on [¹¹C]PLN binding to target regions were observed (p < 0.01).

CONCLUSIONS

In this study, moderate test-retest reproducibility and large inter-subject differences were observed with [¹¹C]PLN PET, possibly attributable to competition by baseline amount of caffeine. Analysis of plasma caffeine concentration is recommended during [¹¹C]PLN PET studies.

TRIAL REGISTRATION

UMIN000030040.

First clinical assessment of [18F]MC225, a novel fluorine-18 labelled PET tracer for measuring functional P-glycoprotein at the blood-brain barrier

OBJECTIVE

5-(1-(2-[¹⁸F]fluoroethoxy))-[3-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-propyl]-5,6,7,8-tetrahydronaphthalen ([¹⁸F]MC225) is a selective substrate for P-glycoprotein (P-gp), possessing suitable properties for measuring overexpression of P-gp in the brain. This is the first-in-human study to examine safety, radiation dosimetry and P-gp function at the blood-brain barrier (BBB) of [¹⁸F]MC225 in healthy subjects.

METHODS

[¹⁸F]MC225 biodistribution and dosimetry were determined in 3 healthy male subjects, using serial 2 h and intermittent 4 and 6 h whole-body PET scans acquired after [¹⁸F]MC225 injection. Dynamic [¹⁸F]MC225 brain PET (90 min) was obtained in 5 healthy male subjects. Arterial blood was sampled at various time intervals during scanning and the fraction of unchanged [¹⁸F]MC225 in plasma was determined. T1-weighted MRI was performed for anatomical coregistration. Total distribution volume (V_T) was estimated using 1- and 2-tissue-compartment models (1-TCM and 2-TCM, respectively). V_T was also estimated using the Logan graphical method (Logan plot) (t* = 20 min). Surrogate parameters without blood sampling (area-under the curve [AUC] of regional time-activity curves [TACs] and negative slope of calculated TACs) were compared with the V_T values.

RESULTS

No serious adverse events occurred throughout the study period. Although biodistribution implied hepatobiliary excretion, secretion of radioactivity from liver to small intestine through the gallbladder was very slow. Total renal excreted radioactivity recovered during 6 h after injection was < 2%ID. Absorbed dose was the highest in the pancreas (mean ± SD, 203 ± 45 μGy/MBq) followed by the liver (83 ± 11 μGy/MBq). Mean effective dose with and without urination was 17 ± 1 μSv/MBq. [¹⁸F]MC225 readily entered the brain, distributing homogeneously in grey matter regions. 2-TCM provided lower Akaike information criterion scores than did 1-TCM. V_T estimated by Logan plot was well correlated with that of 2-TCM (r² > 0.9). AUCs of TACs were positively correlated with V_T (2-TCM) values (r²: AUC_0-60 min = 0.61, AUC_0-30 min = 0.62, AUC_30-60 min = 0.59, p < 0.0001). Negative slope of SUV TACs was negatively correlated with V_T (2-TCM) values (r² = 0.53, p < 0.0001).

CONCLUSIONS

This initial evaluation indicated that [¹⁸F]MC225 is a suitable and safe PET tracer for measuring P-gp function at the BBB.

Brain 11 C-ITMM PET to longitudinally assess type 1 metabotropic glutamate receptor availability in Alzheimer's disease

BACKGROUND AND PURPOSE

Little evidence exists on the role of type 1 metabotropic glutamate receptor (mGluR1) in the pathophysiology of Alzheimer's disease (AD), although mGluR1 may be involved in the regulation of neuronal excitability and synaptic plasticity. We have recently reported that mGluR1 availability in the early stage of AD is equivalent to that in healthy subjects. This study aimed to address whether mGluR1 availability changes with the progression of AD.

METHODS

Eight patients with AD (79.1 ± 4.6 years) underwent a total of two positron emission tomography (PET) examinations using the mGluR1 radioligand during the early-to-middle stages of AD. The mean interval was 2.8 years. Volumes-of-interest were placed on the frontal, parietal, and temporal cortices, hippocampus, anterior and posterior lobes, and vermis in the cerebellum. The binding potential (BP_ND ) was calculated to estimate mGluR1 availability, applying partial volume correction to the BP_ND values.

RESULTS

No significant difference was observed in BP_ND values between the first and second PET examinations in the frontal cortex (p = 0.94), parietal cortex (p = 0.67), temporal cortex (p = 0.20), hippocampus (p = 0.17), anterior lobe (p = 0.73), posterior lobe (p = 0.21), and vermis (p = 0.22).

CONCLUSION

This study suggests that mGluR1 availability is unchanged in the follow-up period of a few years during the early-to-middle stages of AD.

Metabolic Network Topology of Alzheimer's Disease and Dementia with Lewy Bodies Generated Using Fluorodeoxyglucose Positron Emission Tomography

Background:

Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB) are often misdiagnosed with each other because of similar symptoms including progressive memory loss. The metabolic network topology that describes inter-regional metabolic connections can be generated using fluorodeoxyglucose positron emission tomography (FDG-PET) data with the graph-theoretical method. We hypothesized that different metabolic connectivity underlies the symptoms of AD patients, DLB patients, and cognitively normal (CN) individuals.

Objective:

This study aimed to generate metabolic connectivity using FDG-PET data and assess the network topology to differentiate AD patients, DLB patients, and CN individuals.

Methods:

This study included 45 AD patients, 18 DLB patients, and 142 CN controls. We analyzed FDG-PET data using the graph-theoretical method and generated the network topology in AD patients, DLB patients, and CN individuals. We statistically assessed the topology with global and nodal parameters.

Results:

The whole metabolic network was preserved in CN; however, diffusely decreased connection was found in AD and partially but more deeply decreased connection was observed in DLB. The metabolic topology revealed that the right posterior cingulate and the left transverse temporal gyrus were significantly different between AD and DLB.

Conclusion:

The present findings indicate that metabolic connectivity decreased in both AD and DLB, compared with CN. DLB was characterized restricted but deeper stereotyped network disruption compared with AD. The right posterior cingulate and the left transverse temporal gyrus are significant regions in the metabolic connectivity for differentiating AD from DLB.

[Cross-validation of Quantitative Analytical Software Using 18F-florbetapir PET Imaging]

BACKGROUND

¹⁸F-florbetapir is an amyloid β (Aβ) -targeted ¹⁸F-labeled positron emission tomography (PET) tracer for the clinical diagnosis of Alzheimer's disease. The standardized uptake value ratio (SUVR) serves as a tool with which to differentially diagnose. The present study aimed to cross-validate and compare SUVR derived from Amygo neuro and MIMneuro software.

METHODS

We injected 40 individuals with ¹⁸F-florbetapir and then acquired PET images from 50 to 60 minutes later. All images were separately normalized to the standard ¹⁸F-florbetapir PET template using Amygo neuro and MIMneuro. Volumes of interest (VOIs) were automatically placed on six target regions each in Amygo neuro and MIMneuro. The composite SUVR (cSUVR) and regional SUVR (rSUVR) were calculated from mean values measured in VOI. A cSUVR of>1.10 was defined as representing Aβ positivity. Correlation coefficients were calculated in the two types of software.

RESULTS

A cSUVR>1.10 was determined by Amygo neuro and MIMneuro in 15 of the 40 individuals. The rSUVR in the posterior cingulate, parietal lobe, precuneus, and temporal lobe significantly differed between Amygo neuro and MIMneuro, whereas the cSUVR did not. The SUVR calculated by the two types of software closely correlated to each other (R=0.89-0.96, P<0.05).

CONCLUSIONS

The cSUVR was not different between Amygo neuro and MIMneuro. We suggest that Amygo neuro is comparable to MIMneuro in quantitative analysis using SUVR for ¹⁸F-florbetapir imaging, thus facilitating the use of standardized quantitative approaches to amyloid PET imaging.

Quantitative Evaluation of 18F-Flutemetamol PET in Patients With Cognitive Impairment and Suspected Alzheimer's Disease: A Multicenter Study

Background: In clinical practice, equivocal findings are inevitable in visual interpretation of whether amyloid positron emission tomography (PET) is positive or negative. It is therefore necessary to establish a more objective quantitative evaluation method for determining the indication for disease-modifying drugs currently under development.

Aims: We aimed to determine cutoffs for positivity in quantitative analysis of ¹⁸F-flutemetamol PET in patients with cognitive impairment and suspected Alzheimer's disease (AD). We also evaluated the clinical efficacy of amyloid PET in the diagnosis of AD. This study was registered in the Japan Registry of Clinical Trials (jRCTs, 031180321).

Methods: Ninety-three patients suspected of having AD underwent ¹⁸F-flutemetamol PET in seven institutions. A PET image for each patient was visually assessed and dichotomously rated as either amyloid-positive or amyloid-negative by two board-certified nuclear medicine physicians. If the two readers obtained different interpretations, the visual rating was rerun until they reached consensus. The PET images were quantitatively analyzed using the standardized uptake value ratio (SUVR) and standardized Centiloid (CL) scale with the whole cerebellum as a reference area.

Results: Visual interpretation obtained 61 positive and 32 negative PET scans. Receiver operating characteristic analysis determined the best agreement of quantitative assessments and visual interpretation of PET scans to have an area under curve of 0.982 at an SUVR of 1.13 and a CL of 16. Using these cutoff values, there was high agreement between the two approaches (kappa = 0.88). Five discordant cases had SUVR and CL values ranging from 1.00 to 1.22 and from 1 to 26, respectively. In these discordant cases, either diffuse or mildly focal elevation of cortical activity confused visual interpretation. The amyloid PET outcome significantly altered the diagnosis of AD (χ² = 51.3, p < 0.0001). PET imaging elevated the proportions of the very high likelihood category from 20.4 to 46.2% and the very low likelihood category from 0 to 22.6%.

Conclusion: Quantitative analysis of amyloid PET using ¹⁸F-flutemetamol can objectively evaluate amyloid positivity using the determined cutoffs for SUVR and CL. Moreover, amyloid PET may have added value over the standard diagnostic workup in dementia patients with cognitive impairment and suspected AD.

Head-to-Head Comparison of the Two MAO-B Radioligands, 18F-THK5351 and 11C-L-Deprenyl, to Visualize Astrogliosis in Patients With Neurological Disorders

Three patients with neurological disorders (cerebral infarction, progressive multifocal leukoencephalopathy, and multiple sclerosis) underwent F-THK5351 and C-L-deprenyl PET on the same day to visualize lesions undergoing astrogliosis by measuring MAO-B activity. BPND map and SUV image with F-THK5351 as well as Ki map, Ki/K1 map and SUV image with C-L-deprenyl were created. F-THK5351 BPND maps and SUV images clearly identified the lesions undergoing astrogliosis. C-L-deprenyl Ki/K1 maps were close to F-THK5351 images, but very noisy. Ki maps and SUV images were likely affected by the effect of blood flow. Hence, F-THK5351 is superior to C-L-deprenyl for visualizing lesions undergoing astrogliosis.

Ventricular tachycardia in cardiac sarcoidosis -prognosis, characterization of ventricular substrates and outcomes of treatment-

Background

The prognosis, the underlying substrate and clinical outcomes of treatment are unclear in patients with cardiac sarcoidosis (CS)-related ventricular tachycardia (VT).

Objective

This study investigated the prognosis and the relationship between electroanatomical mapping (EAM) and imaging findings in patients with CS-related VT.

Methods

A total of 203 CS patients (Age 68.1±11.6 years, 87 males) were enrolled at two tertiary care medical centers between 2000 and 2018. All met the 2016 Japanese Circulation Society guidelines for diagnosis of CS. They were followed for a composite of major adverse cardiac events (MACE) including cardiac death, heart transplantation, unscheduled hospitalization for heart failure, and life-threatening ventricular arrhythmias. Distribution of late gadolinium enhancement (LGE) on cardiac MRI (CMR) and/or an abnormal myocardial 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography at diagnosis were examined. The relationship between EAM and the image findings were also analyzed in patients with radiofrequency ablation (RFA) for VT.

Results

During a median follow-up of 53 months, 87 of the 203 patients (43%) experienced a MACE. Baseline factors associated with MACE were presence of sustained VT (HR, 2.43, 95% CI 1.54–3.85, P&lt;0.001), left ventricular ejection fraction below 50% (HR, 1.95 95% CI 1.07–3.56, P=0.029), and abnormal myocardial FDG uptake (HR, 2.42 95% CI 1.04–5.61, P=0.039). Overall, 69 of the 203 patients (34%) experienced sustained VT. Abnormal myocardial FDG uptake was significantly more prevalent in patients with VT than in those without (92.7% vs. 78.5%, P=0.02). A total of 25 patients (9.9%) required RFA for CS-related VT (Age 64.0±8.7 years, 12 males, 1.32±0.56 RFAs per patient). Abnormal electrocardiograms (EGM) were observed in 22 of the 25 patients (88%). LGE was more frequent than abnormal FDG uptake in areas with an abnormal EGM (77% vs. 41%; P=0.002). Over a mean follow-up period of 67-months, 13 of the 25 patients with RFA (52%) remained free of VT episodes (Figure). VT recurred in nine of the 12 patients with RFA and in 17 of the 47 patients without RFA, but was suppressed by intensive pharmacologic therapy such as the combined use of amiodarone and sotalol. In patients with CS-related VT, survival without experiencing a MACE did not differ in participants with or without RFA.

Conclusions

In our 203 CS patients, sustained VT and abnormal FDG uptake were associated with worse cardiac outcomes. The prevalence of abnormal FDG uptake was significantly higher in patients with CS-related VT, LGE on CMR was more frequent within localized areas of an abnormal EGM, suggesting that both scar itself and the associated inflammation were involved in the pathogenesis of CS-related VT. Successful RFA of CS-related VT is still challenging, and recurrence is common. Preprocedural CMR can be useful in detecting abnormal EGMs that are potential targets for substrate ablation.

Funding Acknowledgement

Type of funding source: None

Direct comparison of brain [18F]FDG images acquired by SiPM-based and PMT-based PET/CT: phantom and clinical studies

Background

Silicon photomultiplier-positron emission tomography (SiPM-PET) has better sensitivity, spatial resolution, and timing resolution than photomultiplier tube (PMT)-PET. The present study aimed to clarify the advantages of SiPM-PET in ¹⁸F-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) brain imaging in a head-to-head comparison with PMT-PET in phantom and clinical studies.

Methods

Contrast was calculated from images acquired from a Hoffman 3D brain phantom, and image noise and uniformity were calculated from images acquired from a pool phantom using SiPM- and PMT-PET. Sequential PMT-PET and SiPM-PET [¹⁸F]FDG images were acquired over a period of 10 min from 22 controls and 10 patients. All images were separately normalized to a standard [¹⁸F]FDG PET template, then the mean standardized uptake values (SUV_mean) and Z-score were calculated using MIMneuro and CortexID Suite, respectively.

Results

Image contrast, image noise, and uniformity in SiPM-PET changed 19.2, 3.5, and − 40.0% from PMT-PET, respectively. These physical indices of both PET scanners satisfied the criteria for acceptable image quality published by the Japanese Society of Nuclear Medicine of contrast > 55%, CV ≤ 15%, and SD ≤ 0.0249, respectively. Contrast was 70.0% for SiPM-PET without TOF and 59.5% for PMT-PET without TOF. The TOF improved contrast by 3.5% in SiPM-PET. The SUV_mean using SiPM-PET was significantly higher than PMT-PET and did not correlate with a time delay. Z-scores were also significantly higher in images acquired from SiPM-PET (except for the bilateral posterior cingulate) than PMT-PET because the peak signal that was extracted by the calculation of Z-score in CortexID Suite was increased. The hypometabolic area in statistical maps was reduced and localized using SiPM-PET. The trend was independent of whether the images were derived from controls or patients.

Conclusions

The improved spatial resolution and sensitivity of SiPM-PET contributed to better image contrast and uniformity in brain [¹⁸F]FDG images. The SiPM-PET offers better quality and more accurate quantitation of brain PET images. The SUV_mean and Z-scores were higher in SiPM-PET than PMT-PET due to improved PVE. [¹⁸F]FDG images acquired using SiPM-PET will help to improve diagnostic outcomes based on statistical image analysis because SiPM-PET would localize the distribution of glucose metabolism on Z-score maps.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-020-00337-4.

Cardiac function at diagnosis is important prognostic factor in patients with cardiac sarcoidosis -from Japanese nationwide questionnaire survey-

Background

Sarcoidosis is a systemic non-caseating granulomatous disease of unknown etiology. Cardiac involvement (cardiac sarcoidosis, CS) has been reported to be an important prognostic factor in this disease because of heart failure and/or ventricular arrhythmia, and corticosteroid therapy is usually prescribed to prevent cardiac events. However, little is known about the relationship of cardiac function and concomitant corticosteroid therapy on later cardiac events in CS.

Objective

We evaluated the relationship between prognosis and left ventricular ejection fraction (LVEF) at the time of diagnosis in CS patients from the Japanese nationwide questionnaire survey.

Methods

Total of 757 Japanese patients from 57 hospitals who diagnosed CS were examined. Patients who unsatisfied the criteria of the Japanese new guidelines, or who underwent cardiac transplantations were excluded, and 420 patients (287 females, mean age 60±13 years old, median follow-up periods 1864 days [interquartile range: 845–3159 days]) were analyzed. The relationship of adverse events (all-cause death, cardiovascular death, and appropriate ICD [Implantable Cardioverter Defibrillator] discharge) and LVEF (with corticosteroid 84%) (low LVEF: LVEF≤35% n=98 [with corticosteroid in 78%], moderate LVEF: LVEF 35–50% n=104 [with corticosteroid in 93%], normal LVEF: 50≤LVEF n=218 [with corticosteroid in 83%]) were evaluated respectively.

Results

89 CS patients developed all-cause death (n=50), cardiovascular death (n=30) or appropriate ICD discharge (n=48). The frequency of corticosteroid therapy was not different in the each LVEF group, but Kaplan-Meier analysis revealed that all-cause death, cardiovascular death, and all cardiovascular adverse events were more observed in lower LVEF group (log-rank p&lt;0.0001). Furthermore, multivariate Cox hazard analysis revealed that LVEF was a most important independent prognostic factor in CS.

Conclusion

This Japanese nationwide questionnaire survey data showed that initial LVEF was an independent and strong prognostic predictor in CS, therefore primary prevention would be needed even after starting corticosteroid in patients with decreased cardiac function.

Funding Acknowledgement

Type of funding source: None

Long time clinical course of cardiac sarcoidosis with corticosteroid therapy -from Japanese nationwide questionnaire survey-

Background

Sarcoidosis is a systemic inflammatory syndrome of unknown etiology and cardiac involvement has been reported to be an important prognostic factor in this disease. An autopsy study has reported that the frequency of this cardiac involvement (cardiac sarcoidosis: CS) varies in the different countries and races and very frequent in Japanese patients. We therefore performed the nationwide questionnaire survey and try to clarify the clinical characteristics and corticosteroid effect in CS, especially focused on arrhythmic events in this disease.

Methods

Total of 757 Japanese patients from 57 hospitals who diagnosed CS were examined. Patients who unsatisfied the criteria of the Japanese new guidelines, or who underwent cardiac transplantations were excluded, and 420 patients (287 females, median follow-up periods 1864 days [interquartile range: 845–3159 days]) were analyzed. The clinical outcome and corticosteroid effect were evaluated.

Results

Clinical characteristics at diagnosis was as follows: female dominant (68%), mean age of 60±13 years old, mean left ventricular ejection fraction was 49±16%. Arrhythmic events were very frequently observed as an initial cardiac manifestation in 263 patients (62%) of CS, of which atrioventricular block (AVB) in 174 (41%), ventricular tachycardia (VT) in 73 (17%) and AVB with VT in 17 (4%) (Figure 1A). Pacemaker was implanted in 166 patients (40%) and defibrillators was 137 patients (33%). Corticosteroid was prescribed in 144 (83%) of 174 patients with AVB and in 62 (85%) of 73 patients with VT. Initial dose was mean 47.9 mg and maintenance dose of mean 7.3 mg. Corticosteroid improved VT as good as AVB (27% vs. 29%). However, corticosteroid sometimes worsened VT events compared with AVB (10% vs. 2%) (Figure 1B). During the course of follow-up, 32 patients were needed to increase corticosteroid in 23 of AVB and 10 of VT cases. However, there were no difference in mortality between the groups, whether or not to increase corticosteroid. All survival rate was 92% (5-year mortality), 83% (10-year mortality) and free from all cause death and defibrillator charge was 81% (5 year), 71% (10 year).

Conclusion

Fatal arrhythmia is commonly observed in CS as a primary symptom. Corticosteroid sometimes worsen ventricular arrhythmia and appropriate defibrillator discharge was common. Thus, careful attention for activating ventricular arrhythmia would be needed during the follow-up period even after corticosteroid therapy.

Funding Acknowledgement

Type of funding source: None

Long-term follow up ventricular tachycardia patients with preserved cardiac function -from Japanese cardiac sarcoidosis nationwide questionnaire survey-

Background

Prior ventricular tachycardia (VT) and low left ventricular ejection fraction (LVEF) are the most important prognostic factors in cardiac sarcoidosis (CS). Recently diagnosis of CS was renewed according to Japanese new guidelines. Patients with preserved cardiac function often have VT events, thus new guidelines recommends to assess the implantable cardioverter defibrillator (ICD) implantation for CS patients with preserved LVEF (35%≤LVEF&lt;50%). However, the long-term prognosis of CS patients with preserved LVEF is unclear.

Objective

In CS patients with preserved LVEF, we evaluated the prognosis between VT manifestation and non-VT manifestation groups at CS diagnosis from Japanese nationwide questionnaire survey.

Methods

Total of 757 Japanese patients from 57 hospitals who diagnosed CS were examined. Patients who unsatisfied the criteria of the Japanese new guidelines, who had LVEF≤35%, LVEF&gt;50%, or who underwent cardiac transplantations were excluded. 104 patients with LVEF 35–50% (67 females, mean age 60±15 years old, median follow-up periods 2134 days [interquartile range: 758–2935 days]) were analyzed. The prognosis between VT manifestation and non-VT manifestation groups at CS diagnosis were evaluated.

Results

30 patients had VT manifestation at CS diagnosis and 24 patients (80%) received ICDs. 74 patients had no VT manifestation at CS diagnosis and 19 patients (44%) received ICDs during follow up period. All-cause mortality was not different between two groups (Figure). Appropriate ICD therapy of non-VT manifestation group was significantly lower compared with that of VT manifestation group (log-rank p=0.001), however considerable number (n=7, 15%) of non-VT manifestation group had appropriate ICD therapy event during follow-up period. Cox hazard analysis revealed that concomitant non-sustained VT (NSVT) with atrioventricular block (AVB) was a predictor of appropriate ICD therapy in non-VT manifestation group.

Conclusion

This nationwide survey showed that considerable number of CS patients with preserved LVEF had VT events, independent of VT manifestation. Concomitant NSVT with AVB was a predictor of VT events, and ICD implantation should be assessed.

Funding Acknowledgement

Type of funding source: None

Micro-embolic risks during radiofrequency and cryoballoon-ablation of atrial fibrillation -analysis from real-time carotid artery doppler monitoring-

Background

Catheter ablation of atrial fibrillation (AF) is associated with risks of silent cerebral events. However, the timing of intraprocedural micro-embolic events or differences between open-irrigated radiofrequency (RF) and cryoballoon (Cryo) ablation are unclear. Newly developed real-time carotid artery Doppler is a simple non-invasive method to detect micro-embolic signals (MESs) during ablation.

Objective

We investigated the timing of detecting MESs during RF and Cryo ablation of AF.

Methods

During the first pulmonary vein isolation (PVI) session of AF, MESs were monitored by real-time carotid artery Doppler monitoring throughout the procedure. The MES counts were collected and evaluated separately during the different steps of the procedure (Figure).

Results

Thirty-three AF patients (RF/Cryo: 22/11 cases, 9 females, 69.5±11.6 y.o) were included. PVI was successfully accomplished in all patients with no major complications. The MES count was significantly greater in the RF group than Cryo group (table). In both groups, left atrial (LA) access (interatrial puncture) and sheaths insertion to the LA generated a significant number of MESs (RF: 1690 of 9116 MESs [18.5% of the total MESs], Cryo: 793 of 2285 MESs [34.7%]). In the RF group, MESs were observed incessantly during PVI (Figure). The LA dwell time was significantly longer in the RF group than Cryo group (table). In the RF group, the MES count was significantly greater in the longer LA dwell time group (LA dwell time &gt;130min) than the shorter group (464.2±179.7 vs 302.6±138.2: P=0.049). During the cryo-applications in the Cryo group, the MESs were greatest during the first cryoballoon application (625 of 2285 MESs [27.4%]).

Conclusions

There were more MESs during RF ablation than cryoablation. MESs were recorded during a variety of steps throughout the procedure. In the RF group, most of MESs were recorded incessantly during radiofrequency ablation and greater number of MESs were recorded in patients with longer LA dwell time. In the Cryo group, most of MESs occurred during phases with a high probability of gaseous emboli.

Funding Acknowledgement

Type of funding source: None

The safety of catheter ablation of atrial fibrillation in elderly patients -analysis of the nationwide database in Japan, JROAD-DPC-

Background

“Age” is one of the major concerns and determinants of the indications for catheter ablation (CA) of atrial fibrillation (AF). There are little safety data on CA of AF according to the age. This study aimed to assess the safety of CA in elderly patients undergoing CA of AF.

Methods and results

We investigated the complication rate of CA of AF for the different age groups (&lt;60 years, 60–65, 65–70, 70–75, 75–80, 80–85, and ≥85) by a nationwide database (Japanese Registry Of All cardiac and vascular Diseases [JROAD]-DPC). The JROAD-DPC included 73,296 patients (65±11 years, 52,883 men) who underwent CA of AF from 516 hospitals in Japan. Aged patients had more comorbidities and a significantly increased CHADS2 score and higher rate of female according to a higher age. The overall complication rate was 2.6% and in-hospital mortality was 0.05%. By comparing each age group, complications occurred more frequently in higher aged groups. A multivariate adjusted hazard ratio revealed an increased age was independently and significantly associated with the overall complications (odds ratio was 1.25, 1.35, 1.72, 1.86, 2.76 and 3.13 respectively; reference &lt;60 years).

Conclusions

The frequency of complications was significantly higher according to a higher age. We should take note of the indications and procedure for CA of AF in aged patients.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Intramural Research Fund 17 (Kusano) for Cardiovascular Diseases of the National Cerebral and Cardiovascular Center

Effects of aging on coronary flow reserve in patients with no evidence of myocardial perfusion abnormality

Background

Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work.

Purpose

We tested the hypothesis that aging had impacts on coronary flow velocities and CFR in patients with no evidence of myocardial perfusion abnormality on single photon emission computed tomography (SPECT).

Methods and results

Seventy-six patients with no evidence of myocardial perfusion abnormality on SPECT undergoing transthoracic Doppler echocardiography were enrolled in this study. Patients were divided into three age groups: 17 patients aged &lt;70 years (Group I), 38 patients aged 70–79 years (Group II), and 21 patients aged ≥80 years (Group III). Compared with Group I, CFR was significantly lower in Group II (P&lt;0.01) and Group III (P&lt;0.01). Multivariate analysis showed that female (P=0.03), cigarette smoking (P=0.004), hemoglobin level (P=0.001) and LV mass index (P=0.03) were determinants for resting coronary flow velocity. On the other hand, age (P=0.008), hemoglobin level (P&lt;0.001) and LV mass index (P=0.04) were determinants for hyperemic coronary flow velocity. Age was only independent determinant for CFR (β=−0.48 P&lt;0.001).

Conclusions

Our data suggested that aging impaired CFR in patients with no evidence of myocardial perfusion abnormality primarily due to the decrease in hyperemic coronary flow velocity.

Comparison of coronary flow reserve amon

Funding Acknowledgement

Type of funding source: None

Voxel-based morphometry focusing on medial temporal lobe structures has a limited capability to detect amyloid β, an Alzheimer's disease pathology

Voxel-based morphometry (VBM) analysis of nuclear Magnetic Resonance Imaging (MRI) data allows the identification of medial temporal lobe (MTL) atrophy and is widely used to assist the diagnosis of Alzheimer's disease (AD). However, its reliability in the clinical environment has not yet been confirmed. To determine the credibility of VBM, amyloid positron emission tomography (PET) and VBM studies were compared retrospectively. Patients who underwent Pittsburgh Compound B (PiB) PET were retrospectively recruited. Ninety-seven patients were found to be amyloid negative and 116 were amyloid positive. MTL atrophy in the PiB positive group, as quantified by thin sliced 3D MRI and VBM software, was significantly more severe (p =0.0039) than in the PiB negative group. However, data histogram showed a vast overlap between the two groups. The area under the ROC curve (AUC) was 0.646. MMSE scores of patients in the amyloid negative and positive groups were also significantly different (p = 0.0028), and the AUC was 0.672. Thus, MTL atrophy could not reliably differentiate between amyloid positive and negative patients in a clinical setting, possibly due to the wide array of dementia-type diseases that exist other than AD.

Relationship between the temporal course of astrogliosis and symptom improvement in cerebral infarction: report of a case monitored using 18F-THK5351 positron emission tomography

Background

¹⁸F-THK5351 was recently shown to bind to monoamine oxidase B (MAO-B) with high affinity. MAO-B is highly concentrated in astrocytes and increases during astrogliosis. Therefore, ¹⁸F-THK5351 accumulates in lesions undergoing astrogliosis. Cerebral infarction causes astrogliosis, which may be beneficial for repairing and regenerating injured cells and tissues in the lesions. Therefore, monitoring the degree of astrogliosis and stroke symptoms is essential for understanding the roles of astrogliosis in cerebral infarction.

Case presentation

A 72-year-old man, complaining of total loss of sensation in the left index finger, was diagnosed with acute cerebral infarction, and underwent ¹⁸F-THK5351 positron emission tomography (PET) on two occasions after the stroke. The first PET scan performed on day 27 revealed intense uptake in the infarct lesion located around the right precentral and postcentral gyri. However, the second PET scan on day 391 showed that the uptake had diminished significantly. The sensory deficit in the left index finger had improved by 30 and 70% at the times of the first and second PET scans, respectively.

Conclusions

¹⁸F-THK5351 uptake in the infarct lesion evidently changed between days 27 and 391, along with improved sensory deficit in the left index finger. Astrocytes reportedly play a role in restoring neuronal integrity. Therefore, the temporal course of astrogliosis may have been related to improving stroke symptoms in this patient, suggesting that the degree of astrogliosis in the infarct lesion may aid in assessing the prognosis in stroke patients.

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2's Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu's surface age.

P5655Efficacy of new-generation atrial antitachycardia pacing for atrial tachyarrhythmias in patients with left ventricular dysfunction

Background

The progression to persistent atrial fibrillation (AF) is associated with a worse clinical outcome in patients with previous atrial tachyarrhythmias. New-generation atrial antitachycardia pacing (ATP) (Reactive ATP) reduced the progression to persistent AF in patients with pacemaker and preserved left ventricular (LV) function. However, little is known about the efficacy of Reactive ATP in patients with cardiac implantable electronic devices (CIED) and LV dysfunction.

Purpose

We aimed to investigate the efficacy of Reactive ATP for atrial tachyarrhythmias in patients with LV dysfunction (LV ejection fraction [LVEF] <40%).

Methods

This study included 423 patients with CIED and previous atrial tachyarrthythmias. Reactive ATP was programmed in 284 patients (ATP group) and 139 were implanted with a dual-chamber device without ATP function (control group). The differences in the success rate of ATP and incidence of progression to persistent AF (≥7 days) between the ATP and control groups were evaluated in 108 patients with LVEF <40% (reduced LVEF) and 315 with LVEF ≥40% (preserved LVEF). Patients with persistent AF were excluded from this study.

Results

During 710±337 days of follow-up period, 16 patients (15%) with reduced LVEF and 51 (16%) with preserved LVEF progressed to persistent AF (p=0.88). The mean ATP success rate was lower in patients with reduced LVEF than in those with preserved LVEF, although not statistically significant (reduced LVEF: 27.2±19.4% and preserved LVEF: 35.1±29.2%, p=0.12). The incidence of progression to persistent AF was significantly lower in the ATP group than in the control group both in patients with reduced and preserved LVEF (log-rank, reduced LVEF: p=0.0070 and preserved LVEF: p<0.0001) (Figure). Multivariate analysis showed that use of Reactive ATP and smaller left atrium were associated with lower incidences of persistent AF, while LVEF was not predictive of progression to persistent AF (Reactive ATP: hazard ratio [HR] 0.28, 95% confidence interval [CI] 0.17–0.46, p<0.0001, left atrium diameter: HR 1.03, 95% CI 1.00–1.07, p=0.030).

Figure 1

Conclusions

Reactive ATP was effective in preventing AF progression in patients with LV dysfunction.

Vascular endothelial growth factors C and D and lymphangiogenesis at the early stage of esophageal squamous cell carcinoma progression

We conducted a detailed study of lymphangiogenesis and subsequent lymph node metastasis in early-stage esophageal squamous cell carcinoma (ESCC) using immunostaining for D2-40 and vascular endothelial growth factor (VEGF)-C and D. The study materials included 13 samples of normal squamous epithelium, 6 samples of low-grade intraepithelial neoplasia (LGIN), and 60 samples of superficial ESCC (M1 and M2 cancer 24; M3 or deeper cancer 36). We assessed lymphatic vessel density (LVD) using D2-40 and immunoreactivity for VEGF-C and D in relation to histological type, lymphatic invasion, and lymph node metastasis. LVD in M1 and M2 lesions and M3 or deeper lesions was significantly higher than in normal squamous epithelium (P < 0.001). High expression of VEGF-C and D was observed in M1 and M2 cancer and in M3 or deeper cancer, but not in normal squamous epithelium or LGIN. LVD in VEGF-C- and D-positive cases was significantly higher than in negative cases (P < 0.001). In M3 or deeper cancer, the correlation between VEGF-C or D status and lymphatic invasion or lymph node metastasis was not significant. LVD in cases with positive lymphatic invasion and those with lymph node metastasis was significantly higher than in cases lacking either (P = 0.02 and 0.03, respectively). ESCC cells produce VEGF-C and D from the very early stage of progression. VEGF-C and D activate lymphangiogenesis, and this increase of lymphatic vessels leads to lymphatic invasion and subsequent lymph node metastasis.