Hirotaka Shimada

CSF levels of Aβ1-38/Aβ1-40/Aβ1-42 and (11)C PiB-PET studies in three clinical variants of primary progressive aphasia and Alzheimer's disease.

Abstract Primary progressive aphasia (PPA) is a cognitive syndrome characterized by progressive and isolated language impairments due to neurodegenerative diseases. Recently, an international group of experts published a Consensus Classification of the three PPA clinical variants (naPPA, svPPA and lvPPA). We analyzed 24 patients with PPA by cognitive functions, neuroimaging (MRI, 99 mTc ECD-SPECT, 11C PiB-PET and FDG-PET) and cerebrospinal fluid (CSF) analysis (ptau-181, Aβ1-42, Aβ1-40 and Aβ1-38), to elucidate relationships between neuroimaging studies and biochemical findings in the three PPA clinical variants. Cognitive and speech functions were measured by mini-mental state examination and standard language test of aphasia. The patients with lvPPA showed significant decreases in CSF Aβ1-42 and ratios of Aβ1-42/Aβ1-40 and Aβ1-42/Aβ1-38, and significant increases in CSF ptau-181 and ratios of ptau-181/Aβ1-42 and ptau-181/Aβ1-38; these findings were similar to those of patients with Alzheimer’s disease (AD). We observed a higher frequency of the ApoE ε4 allele in the lvPPA patients relative to the two other PPA variants. In 11C PiB-PET of lvPPA patients, PiB positive findings were detected in cortices of frontal, temporal and parietal lobes and the posterior cingulate, where massive Aβ may accumulate due to AD. Our results of AD-CSF markers including Aβ1-38 and 11C PiB-PET in the lvPPA patients demonstrate a common pathological mechanism with the occurrence of AD.

Improvements in Segmentation Using Scatter and Photopeak Window Data for Attenuation Correction in Myocardial SPECT

Background: The method of Segmentation with Scatter and Photopeak window data in Attenuation Correction (SSPAC) recognizes the outlines of the body around chest and lungs using scatter window data after which an attenuation correction (μ) map can be constructed.We have developed a new extraction method, adding a masking process to SSPAC, because the extraction of outlines was otherwise incomplete. Methods and Results: The masking process extracted right and left lung fields from chest images.The quality of the masking process was confirmed by the results from a low count phantom.In a case study, automatic extraction by SSPAC had a 44% success rate for low count (stress condition) myocardial single-photon emission computed tomography (SPECT) images, but reached a success rate of 99% with the addition of the new masking process.Outline truncation and low counts can cause unsuccessful SSPAC. Conclusions: Our method for masking will contribute to a widespread use of SSPAC by improving the success rate in contouring.

CLINICAL FEATURES OF POSTERIOR CORTICAL ATROPHY VERSUS ALZHEIMER'S DISEASE

(Mean/SD) was 6.50 (5.49). According to their MADRS scores, the sample was composed of mild to moderate depressed patients. Seventy percent of the sample had late onset depression. Their mean MMSE, CAMCOG, B-ADL scores were respectively 24.90 (64.19), 81.87 (615.47) and 2.44 (61.13). The Small Volume Correction Tool (SVC) showed positive correlations between GM volumes and MMSE (Right Inferior Temporal Gyrus, p1⁄40.026, 209 voxels) and between GM volumes and CAMCOG (Right Inferior Temporal Gyrus, p1⁄40.004, 471 voxels) and Left Inferior Temporal Gyrus (p1⁄40.026, 114 voxels). No negative correlations were found. Conclusions: These findings highlight the relationship between cognitive performance and volumes of temporal structures in elderly depressed individuals. The positive correlation between MMSE and CAMCOG scores with temporal volumes specifically in elderly depressed individuals provides support to the view that at least a subtype of depression in the elderly may be a risk factor or a prodomic syndrome for AD.

Improvement of image resolution of brain SPECT by use of the wide-angle offset acquisition method

ObjectiveCerebral SPECT images require high spatial and contrast resolution for precise evaluation of the abnormal tracer distribution in the brain. A shorter data acquisition time is preferable so that artifacts due to patient movement are avoided. We tried to shorten data acquisition time applying larger sampling angle and offset acquisition method, in which half degree of the step angle was shifted in the opposite gamma camera of the dual-detector SPECT system.MethodsA simulation study was performed with a 3-dimensional mathematical phantom. The phantom studies were performed with a hot-rod phantom and a brain phantom. A clinical study with 99mTc-ECD SPECT was also performed on a patient who had a cerebral infarction. Reconstruction of images was done for the normal 6° and 12° onset and 12° offset. Data for the 12° offset were acquired by shifting of sampling angles of the opposite detector by half (6°) of the sampling angles of 12°. The MLEM algorithm was used for image reconstruction. Image qualities in the simulation study, the phantom studies, and the clinical study were compared for the 6° and 12° onset, and for the 12° offset by quantitative analysis with use of profile curves.ResultsAnalysis of the profile curves revealed that the image quality of the 12° offset was better than that of the 12° onset and compared to that of the 6° onset in the simulation study, the phantom studies, and the clinical study.ConclusionsThe present study indicates that wide-angle offset data acquisition improves the image resolution of brain SPECT compared to onset data acquisition with the same sampling time.