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 mean standardized uptake values (SUVmean) 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 SUVmean 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 SUVmean 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.

Cognitive Abilities Screening Instrument (CASI) were deteriorated except for long-term memory and visual construction in the MCI participants compared with healthy adults, suggesting that MCI is similar to very mild Alzheimer's disease (AD). Objective: We herein report the neuropsychological features of MCI with reference to regional cerebral blood flow (rCBF) especially in the hippocampus and frontal lobe. Methods: Patients: 24 MCI subjects were studied. They met the following criteria: subjective memory complaints and/or family observation for their memory impairment; the score on WMS-R Logical Memory I to be less 13; the MMSE scores were greater than 24; normal daily living; and the CDR score was 0.5 with memory domain being 0.5 and other domains being 0 or 0.5. Written informed consent was obtained from all the participants. Cognitive assessments: The CASI and the Trail-Making Tests A (TMT-A) and B (TMT-B) were used. The CASI was used for assessing 9 domains, i.e., remote memory, recent memory, attention, concentration/ mental manipulation, orientation, visual construction, abstraction & judgment, list-generating fluency, and language. SPECT: The rCBF was measured qualitatively using the [ 123 I]-N-isopropyl-p-iodoamphetamine and single photon emission tomography (SPECT), and region of interest (ROI) analysis was performed using 3DSRT software. We evaluated the relationship between the scores of CASI domains and rCBF of the frontal and hippocampal ROIs using the cerebellum as a reference. Results: We found that decreased rCBF in the hippocampus was correlated with CASI domains recent memory (Spearman, pϽ0.01). Decreased rCBF in the frontal lobes were associated with frontal executive dysfunction as measured by the TMT-A and TMT-B (Spearman, pϽ0.01). The MCI subjects with more decreased executive function were rated as 0.5 in the non-memory CDR domains. Conclusions: Clinical subtypes of MCI based on CDR domains were associated with neurological and neuropsychological backgrounds. Further decline to dementia with reference to such backgrounds would be investigated. P2-021A Background: Although successful visualization of amyloid deposits in the APP transgenic mouse brain with MR imaging has been reported recently, there is no suitable method to measure plaque load (PL). We present a novel method based on simulated flooding (watersheds) to segment amyloid plaques in mouse brain images. In this method, the image is segmented into catchment basins (CB) associated with local minima and CBs that correspond to plaques are selected using the data Laplacian as a feature describing local variation. Besides PL (volume fraction) estimation, our method can be also used to analyze other plaque characteristics such as size, shape and distribution. Methods: The automatic plaque segmentation algorithm has two steps: First, simulated flooding is used to extract regions with low intensities completely surrounded by higher intensity neighbors. The resulting map defines the CBs of the MR local minima. Second, the image Laplacian ...

Purpose Fusion images of positron emission tomography ( PET and magnetic resonance image MRI are effective to evaluate pathological changes using anatomical information. Registration of PET and MRI based on normalized mutual information (NMI) is widely used , where PET images change a lot depending on not only the choice of tracers but also disease progress ion , but the co registration accuracy has not been confirmed well yet. The aim of this study is to clarify the accuracy of NMI based registration between MRI and PET (amyloid PET and tau PET). Methods We obtained PET and MRI data from 69 participants (ages from 47 to 87 ) who underwent PET using one of the following four tracers 11 C PiB, 18 F Florbetapir, 11 C PBB3 or 18 F THK5351. T he ground truth (i .e .., a set of registered MRI PET images) was manually made by two experts. For each data set, 40 set of perturbed parameters were given to MR image s . Then each perturbed MR I was registered to the PET image using the statistical parametric mapping (SPM) tool. The differences between the given and the estimated shifts and rotates were calculated as registration errors. Results We found the registration errors were around 2 mm in the shift and around 1 deg in the rotation. These registration errors were independent of the amount of the perturbation given. Conclusion Although negative subjects of tau tracers showed higher error than other tracers, the registration error was less than PET spatial resolution, which supported a proof of the stability of the SPM.

Abstract Background: The silicon photomultiplier-positron emission tomography (SiPM-PET) developed by GE Healthcare has better sensitivity, spatial resolution, and timing resolution than photomultiplier tubes (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: Image contrast was calculated from images acquired from a Hoffman 3D brain phantom and image noise and uniformity were calculated from pooled 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 mean standardized uptake values (SUVmean) and Z-score were calculated by 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 > 55%, ≤ 15% and ≤ 0.0249, respectively. The contrast in SiPM-PET was slightly improved using TOF. The SUVmean 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 raised. The area of hypometabolism in statistical maps was reduced and localized by SiPM-PET compared with PMT-PET regardless 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 SUVmean and Z-score in SiPM-PET was higher than PMT-PET due to improving the PVEs. [18F]FDG images acquired using SiPM-PET will help to improve diagnostic outcomes based on statistical image analysis becausethe SiPM-PET would localize the distribution of glucose metabolism on Z-score maps.