Estimation of post-therapeutic liver reserve capacity using 99mTc-GSA scintigraphy prior to carbon-ion radiotherapy for liver tumors.

BACKGROUND: There is currently no established imaging method for assessing liver reserve capacity prior to carbon-ion radiotherapy (CIRT) for liver tumors. In order to perform safe CIRT, it is essential to estimate the post-therapeutic residual reserve capacity of the liver. PURPOSE: To evaluate the ability of pre-treatment 99mTc-galactosyl human serum albumin (99mTc-GSA) scintigraphy to accurately estimate the residual liver reserve capacity in patients treated with CIRT for liver tumors. MATERIALS AND METHODS: This retrospective study evaluated patients who were performed CIRT for liver tumors between December 2018 and September 2020 and underwent 99mTc-GSA scintigraphy before and 3 months after CIRT, and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI within 1 month before CIRT were evaluated. The maximal removal rate of 99mTc-GSA (GSA-Rmax) was analyzed for the evaluation of pre-treatment liver reserve capacity. Then, the GSA-Rmax of the estimated residual liver (GSA-RL) was calculated using liver SPECT images fused with the Gd-EOB-DTPA-enhanced MRI. GSA-RL before CIRT and GSA-Rmax at 3 months after CIRT were compared using non-parametric Wilcoxon signed-rank test and linear regression analysis. RESULTS: Overall, 50 patients were included (mean age ± standard deviation, 73 years ± 11; range, 29-89 years, 35 men). The median GSA-RL was 0.393 [range, 0.057-0.729] mg/min, and the median GSA-Rmax after CIRT was 0.369 [range, 0.037-0.780] mg/min (P = .40). The linear regression equation representing the relationship between the GSA-RL and GSA-Rmax after CIRT was y = 0.05 + 0.84x (R2 = 0.67, P < .0001). There was a linear relationship between the estimated and actual post-treatment values for all patients, as well as in the group with impaired liver reserve capacity (y = - 0.02 + 1.09x (R2 = 0.62, P = .0005)). CONCLUSIONS: 99mTc-GSA scintigraphy has potential clinical utility for estimating the residual liver reserve capacity in patients undergoing carbon-ion radiotherapy for liver tumors. TRIAL REGISTRATION: UMIN000038328, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000043545 .

Combination of Astrogliosis and Phosphorylated Tau for the Preclinical Diagnosis of Alzheimer Disease Using 3-Dimensional Stereotactic Surface Projection Images With 18 F-THK5351.

ABSTRACT: The Alzheimer disease (AD) brain is characterized microscopically by the presence of extracellular amyloid plaques and intraneuronal neurofibrillary tangles consisting of phosphorylated tau aggregations. 18 F-THK5351 is a first-generation PET tau tracer that also binds to monoamine oxidase B, which represents astrogliosis, and is useful to evaluate some non-AD neurodegenerative disorders. We examined the utility of 18 F-THK5351 in preclinical AD using 3-dimensional stereotactic surface projection images optimized for its pathological accumulation by comparison with a normal dataset. By using this 18 F-THK5351 3-dimensional stereotactic surface projection procedure, which can evaluate phosphorylated tau and neuroinflammation, we could diagnose preclinical AD effectively.

Automated semi-quantitative amyloid PET analysis technique without MR images for Alzheimer's disease.

OBJECTIVE: Although beta-amyloid (Aß) positron emission tomography (PET) images are interpreted visually as positive or negative, approximately 10% are judged as equivocal in Alzheimer's disease. Therefore, we aimed to develop an automated semi-quantitative analysis technique using 18F-flutemetamol PET images without anatomical images. METHODS: Overall, 136 cases of patients administered 18F-flutemetamol were enrolled. Of 136 cases, five PET images each with the highest and lowest values of standardized uptake value ratio (SUVr) of cerebral cortex-to-pons were used to create positive and negative templates. Using these templates, PET images of the remaining 126 cases were standardized, and SUVr images were produced with the pons as a reference region. The mean of SUVr values in the volume of interest delineated on the cerebral cortex was compared to those in the CortexID Suite (GE Healthcare). Furthermore, centiloid (CL) values were calculated for the 126 cases using data from the Centiloid Project ( http://www.gaain.org/centiloid-project ) and both templates. 18F-flutemetamol-PET was interpreted visually as positive/negative based on Aß deposition in the cortex. However, the criterion "equivocal" was added for cases with focal or mild Aß accumulation that were difficult to categorize. Optimal cutoff values of SUVr and CL maximizing sensitivity and specificity for Aß detection were determined by receiver operating characteristic (ROC) analysis using the visual evaluation as a standard of truth. RESULTS: SUVr calculated by our method and CortexID were highly correlated (R2 = 0.9657). The 126 PET images comprised 84 negative and 42 positive cases of Aß deposition by visual evaluation, of which 11 and 10 were classified as equivocal, respectively. ROC analyses determined the optimal cutoff values, sensitivity, and specificity for SUVr as 0.544, 89.3%, and 92.9%, respectively, and for CL as 12.400, 94.0%, and 92.9%, respectively. Both semi-quantitative analyses showed that 12 and 9 of the 21 equivocal cases were negative and positive, respectively, under the optimal cutoff values. CONCLUSIONS: This semi-quantitative analysis technique using 18F-flutemetamol-PET calculated SUVr and CL automatically without anatomical images. Moreover, it objectively and homogeneously interpreted positive or negative Aß burden in the brain as a supplemental tool for the visual reading of equivocal cases in routine clinical practice.

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 (ß) in BPL requires optimization according to the radiopharmaceutical tracer. The present study aimed to define the optimal ß value in BPL required to diagnose Alzheimer disease from brain positron emission tomography (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/computed tomography (CT) 710 and reconstructed using OSEM + time-of-flight (TOF) under clinical conditions and BPL + TOF (ß = 20-1000). 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 ß 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 ß 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 ß = 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 ß = 150-1000 and 400-1000 for [18 F]FDG and [11 C]PiB, respectively. The phantom study restricted the ranges of ß values to 100-300 and 300-500 for [18 F]FDG and [11 C]PiB, respectively. The BPL scores for gray-white matter contrast and image noise, exceeded those of OSEM in [18 F]FDG and [11 C]PiB images regardless of ß values. Visual evaluation confirmed that the optimal ß 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 standardized uptake value ratios (SUVR) due to full convergence, more rigorous noise control, and edge preservation. The optimal ß 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 ß values in BPL for brain PET imaging.

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 (VT) was estimated using 1- and 2-tissue-compartment models (1-TCM and 2-TCM, respectively). VT 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 VT 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. VT estimated by Logan plot was well correlated with that of 2-TCM (r2 > 0.9). AUCs of TACs were positively correlated with VT (2-TCM) values (r2: AUC0-60 min = 0.61, AUC0-30 min = 0.62, AUC30-60 min = 0.59, p < 0.0001). Negative slope of SUV TACs was negatively correlated with VT (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.

Visualization of Motor Cortex Involvement by 18F-THK5351 PET Potentially Strengthens Diagnosis of Amyotrophic Lateral Sclerosis.

ABSTRACT: Amyotrophic lateral sclerosis (ALS) involves both upper motor neurons (UMNs) and lower motor neurons. The detection of UMN involvement, a core component of ALS criteria, is primarily dependent on neurological examination because of a lack of definitive biomarkers. We present the 18F-THK5351 PET images of a 76-year-old man diagnosed with ALS comorbid with Alzheimer disease, demonstrating marked accumulation of 18F-THK5351 in the bilateral precentral gyri. Because 18F-THK5351 binds to monoamine oxidase B highly expressed in astrocytes, where the neurodegenerative process is ongoing, our case highlights that 18F-THK5351 tracer should be a useful marker for detecting UMN neurodegeneration in ALS.

Dissociation of Tau Deposits and Brain Atrophy in Early Alzheimer's Disease: A Combined Positron Emission Tomography/Magnetic Resonance Imaging Study.

The recent advent of tau-specific positron emission tomography (PET) has enabled in vivo assessment of tau pathology in Alzheimer's disease (AD). However, because PET scanners have limited spatial resolution, the measured signals of small brain structures or atrophied areas are underestimated by partial volume effects (PVEs). The aim of this study was to determine whether partial volume correction (PVC) improves the precision of measures of tau deposits in early AD. We investigated tau deposits in 18 patients with amyloid-positive early AD and in 36 amyloid-negative healthy controls using 18F-THK5351 PET. For PVC, we applied the SPM toolbox PETPVE12. The PET images were then spatially normalized and subjected to voxel-based group analysis using SPM12 for comparison between the early AD patients and healthy controls. We also compared these two groups in terms of brain atrophy using voxel-based morphometry of MRI. We found widespread neocortical tracer retention predominantly in the posterior cingulate and precuneus areas, but also in the inferior temporal lobes, inferior parietal lobes, frontal lobes, and occipital lobes in the AD patients compared with the controls. The pattern of tracer retention was similar between before and after PVC, suggesting that PVC had little effect on the precision of tau load measures. Gray matter atrophy was detected in the medial/lateral temporal lobes and basal frontal lobes in the AD patients. Interestingly, only a few associations were found between atrophy and tau deposits, even after PVC. In conclusion, PVC did not significantly affect 18F-THK5351 PET measures of tau deposits. This discrepancy between tau deposits and atrophy suggests that tau load precedes atrophy.

[Cingulate Island Sign].

The Dementia with Lewy Bodies (DLB) Consortium refined its recommendations for the clinical diagnosis of DLB last year. The generalized low uptake of single photon emission computed tomography (SPECT)/positron emission tomography (PET) perfusion/metabolism scan with reduced occipital activity with or without the cingulate island sign (CIS) in FDG-PET imaging was described as a supportive biomarker of DLB. CIS shows that brain metabolism in the posterior cingulate of patients with DLB is relatively preserved compared with Alzheimer's disease (AD). Metabolism in the posterior cingulate is known to be dicreased in patients with AD. CIS is also known to have negative correlation with the Braak neurofibrillary tangle stages. Recently, we studied CIS of brain perfusion SPECT and concluded that optimized CIS using brain perfusion SPECT is clinically useful for differentiating DLB from AD. This feasibility of studying CIS using brain perfusion SPECT when diagnosing DLB is described in this article.

Voxel-based Specific Regional Analysis System for Alzheimer's Disease (VSRAD) on 3-tesla Normal Database: Diagnostic Accuracy in Two Independent Cohorts with Early Alzheimer's Disease.

Voxel-based specific regional analysis system for Alzheimer's disease (VSRAD) software is widely used in clinical practice in Alzheimer's disease (AD). The existing VSRAD is based on the normal database with 1.5-tesla MRI scans (VSRAD-1.5T), and its utility for patients have undergone 3-tesla MRI is still controversial. We recruited 19 patients with early AD and 28 healthy controls who had undergone 3-tesla MRI scans at our institute (Cohort 1). We also used the 3-tesla MRI data of 30 patients with early AD and 13 healthy controls from the Japanese Alzheimer's Disease Neuroimaging Initiative (Cohort 2). We also created a new VSRAD based on 65 normal subjects' 3-tesla MRI scans (VSRAD-3T), and compared the detectability of AD between VSRAD-1.5T and VSRAD-3T, using receiver operating characteristic curve and area under the curve (AUC) analyses. As a result, there were no significant differences in the detectability of AD between VSRAD-3T and VSRAD-1.5T, except for the whole white matter atrophy score, which showed significantly better AUC in VSRAD-3T than in VSRAD-1.5T in both Cohort 1 (p=0.04) and 2 (p<0.01). Generally, there were better diagnostic values in Cohort 2 than in Cohort 1. The optimal cutoff values varied but were generally lower than in the previously published data. In conclusion, for patients with 3-tesla MRI, the detectability of early AD by the existing VSRAD was not different from that by the new VSRAD based on 3-tesla database. We should exercise caution when using the existing VSRAD for 3-tesla white matter analyses or for setting cutoff values.

Anserine/Carnosine Supplementation Preserves Blood Flow in the Prefrontal Brain of Elderly People Carrying APOE e4.

In a previously reported double-blind, randomized controlled trial (RCT), we demonstrated that daily supplementation with anserine (750 mg) and carnosine (250 mg) improves brain blood flow and memory function in elderly people. Here, we conducted a sub-analysis of MRI data and test scores from the same RCT to determine whether anserine/carnosine supplementation specifically benefits elderly people carrying the APOE e4 allele, which is a risk gene for accelerated brain aging and for the onset of Alzheimer's Disease. We collected data from 68 participants aged 65 years or older who received anserine/carnosine supplementation (ACS) or placebo for 12 months. Subjects were assessed at the start and end of the trial using several neuropsychological tests, including the Wechsler Memory Scale-Logical Memory (WMS-LM). We also collected two types of MRI data, arterial spin labeling (ASL) and diffusion tensor imaging (DTI) at the start and end of the trial. We found that ACS significantly preserved verbal memory (WMS-LM, F[1,65] = 4.2003, p = 0.0445) and blood flow at frontal areas of the brain (FWEcluster level, p < 0.001). Sub-analysis based on the APOE4 genotype showed a significant preservation of blood flow (p = 0.002, by ASL analysis) and white-matter microstructure (p = 0.003, by DTI analysis) at prefrontal areas in APOE4+ subjects in the active group, while there was no significant difference between APOE4- subjects in the active and placebo groups. The effect of ACS in preserving brain structure and function in elderly people carrying APOE4 should be verified by further studies.

Japanese multicenter database of healthy controls for [123I]FP-CIT SPECT.

PURPOSE: The aim of this multicenter trial was to generate a [123I]FP-CIT SPECT database of healthy controls from the common SPECT systems available in Japan. METHODS: This study included 510 sets of SPECT data from 256 healthy controls (116 men and 140 women; age range, 30-83 years) acquired from eight different centers. Images were reconstructed without attenuation or scatter correction (NOACNOSC), with only attenuation correction using the Chang method (ChangACNOSC) or X-ray CT (CTACNOSC), and with both scatter and attenuation correction using the Chang method (ChangACSC) or X-ray CT (CTACSC). These SPECT images were analyzed using the Southampton method. The outcome measure was the specific binding ratio (SBR) in the striatum. These striatal SBRs were calibrated from prior experiments using a striatal phantom. RESULTS: The original SBRs gradually decreased in the order of ChangACSC, CTACSC, ChangACNOSC, CTACNOSC, and NOACNOSC. The SBRs for NOACNOSC were 46% lower than those for ChangACSC. In contrast, the calibrated SBRs were almost equal under no scatter correction (NOSC) conditions. A significant effect of age was found, with an SBR decline rate of 6.3% per decade. In the 30-39 age group, SBRs were 12.2% higher in women than in men, but this increase declined with age and was absent in the 70-79 age group. CONCLUSIONS: This study provided a large-scale quantitative database of [123I]FP-CIT SPECT scans from different scanners in healthy controls across a wide age range and with balanced sex representation. The phantom calibration effectively harmonizes SPECT data from different SPECT systems under NOSC conditions. The data collected in this study may serve as a reference database.

A structural MRI study of cholinergic pathways and cognition in multiple sclerosis.

BACKGROUND: White matter hyperintensities (WMH) in the cholinergic pathways are associated with cognitive performance in Alzheimer's disease. This study aimed to evaluate the relationship between the volume reduction of cholinergic pathways and cognitive function in patients with multiple sclerosis (MS). METHODS: Thirty-two MS patients underwent a brain MRI and cognitive measurements including the Mini-Mental State Examination (MMSE) and the Japanese version of the Montreal Cognitive Assessment (MoCA-J). The extent of WMH within the cholinergic pathways was assessed using the Cholinergic Pathways Hyperintensities Scale (CHIPS). Computerized WMH volumes were also obtained. FreeSurfer was used to measure regional volumes including the cortical and subcortical volumes. The correlations among the CHIPS, the WMH volume, and the clinical data were assessed, in addition to the correlations between the cognitive scores and regional volumes measured by FreeSurfer. RESULTS: The CHIPS score and the WMH volume were strongly positively correlated with each other (r = 0.87, P < 0.001). The CHIPS score had significantly negative correlations with the MMSE (r = - 0.49, P = 0.003) and the MoCA-J (r = - 0.47, P = 0.005) results. The WMH volume had significantly negative correlations with the MMSE (r = - 0.54, P = 0.001) and the MoCA-J (r = - 0.57, P < 0.001) results. In the analysis by FreeSurfer, both the MMSE and MoCA-J scores had significant positive correlations only with the volume of the corpus callosum. CONCLUSIONS: The CHIPS score tended to be less sensitive to the WMH volume in cognitive function evaluation, although the difference did not reach the level of statistical significance. Thus the CHIPS method may not be as effective in MS patients.

Anserine/Carnosine Supplementation Suppresses the Expression of the Inflammatory Chemokine CCL24 in Peripheral Blood Mononuclear Cells from Elderly People.

Our goal was to determine whether anserine/carnosine supplementation (ACS) suppresses chemokine levels in elderly people. In a double-blind randomized controlled trial, volunteers were assigned to the ACS or placebo group (1:1). Sixty healthy elderly volunteers (active, n = 30; placebo, n = 30) completed the study. The ACS group was administered 1.0 g of anserine/carnosine (3:1) for 3 months. A microarray analysis and subsequent quantitative real-time polymerase chain reaction (qRT-PCR) analysis of peripheral blood mononuclear cells (PBMCs) showed decreased expression of CCL24, an inflammatory chemokine (p < 0.05). Verbal memory, assessed using the Wechsler memory scale-logical memory, was preserved in the ACS group. An age-restricted sub-analysis showed significant verbal memory preservation by ACS in participants who were in their 60s (active, n = 12; placebo, n = 9; p = 0.048) and 70s (active, n = 7; placebo, n = 11; p = 0.017). The suppression of CCL24 expression was greatest in people who were in their 70s (p < 0.01). There was a significant correlation between the preservation of verbal memory and suppression of CCL24 expression in the group that was in the 70s (Poisson correlation, r = 0.46, p < 0.05). These results suggest that ACS may preserve verbal episodic memory, probably owing to CCL24 suppression in the blood, especially in elderly participants.

Correlations between dopamine transporter density measured by 123I-FP-CIT SPECT and regional gray matter volume in Parkinson's disease.

PURPOSE: Parkinson's disease (PD) is caused by a selective degeneration of dopamine neurons. The relationship between dopamine transporter (DAT) density and gray matter volume has been unclear. Here we investigated the voxelwise correlation between gray matter volume and DAT binding measured by 123I-N-ω-fluoropropyl-2ß-carboxymethoxy-3ß-(4-iodophenyl)nortropane (123I-FP-CIT) single-photon emission computed tomography (SPECT; DaTscan™ imaging) in PD. MATERIALS AND METHODS: Thirty-one male patients with PD were examined with MRI and DaTscan. To measure nigrostriatal dopaminergic degeneration in PD, the specific binding ratio (SBR) of the striatum was obtained by DaTscan. Voxel-based morphometry (VBM) of 3D T1-weighted images was used to evaluate the relationships between the regional gray matter volume and the SBR in the striatum. RESULTS: There were significant positive correlations between the SBR and the gray matter volume in the right pulvinar and posterior middle temporal gyrus and a trend level in the left pulvinar, all of which are associated with the second visual pathway. CONCLUSION: The nigrostriatal dopaminergic degeneration might affect the secondary visual pathway, leading to visual dysfunctions in PD.

Regional tau deposition and subregion atrophy of medial temporal structures in early Alzheimer's disease: A combined positron emission tomography/magnetic resonance imaging study.

INTRODUCTION: Molecular imaging and selective hippocampal subfield atrophy are a focus of recent Alzheimer's disease (AD) research. Here, we investigated correlations between molecular imaging and hippocampal subfields in early AD. METHODS: We investigated 18 patients with early AD and 18 healthy control subjects using 11C-Pittsburgh compound-B (PIB) positron emission tomography (PET) and 18F-THK5351 PET and automatic segmentation of hippocampal subfields with high-resolution T2-weighted magnetic resonance imaging. The PET images were normalized and underwent voxelwise regression analysis with each subregion volumes using SPM12. RESULTS: As for 18F-THK5351 PET, the bilateral perirhinal cortex volumes were significantly associated with the ipsilateral or bilateral temporal lobar uptakes, whereas hippocampal subfields showed no correlations. 11C-PIB PET showed relatively broad negative correlation with the right cornu ammonis 3 volumes. DISCUSSION: Regional tau deposition was correlated with extrahippocampal subregional atrophy and not with hippocampal subfields, possibly reflecting different underlying mechanisms of atrophy in early AD. Amyloid might be associated with right cornu ammonis 3 atrophy.