Regions of interest were placed on normalized PET images according to the previous rs-fMRI study. Quantitative CBF and CMRO 2 images were generated by an autoradiographic method and transformed into MNI standardized brain template. Nine healthy volunteers (5 men and 4 women mean age, 47.0 ± 1.2 years) were studied by means of 15 O-O 2, 15 O-CO gases and 15 O-water PET. In this study, we attempted to estimate the functional correlations in the DMN by means of quantitative 15 O-labeled gases and water PET, and to compare the contribution of the CBF and CMRO 2 to the DMN. However, these two factors cannot be separated in BOLD rs-fMRI. The BOLD signal reflects the deoxyhemoglobin concentration, which depends on the relationship between the regional cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO 2 ). Resting-state functional MRI (rs-fMRI) has revealed the existence of a default-mode network (DMN) based on spontaneous oscillations of the blood oxygenation level-dependent (BOLD) signal. DRAMA reconstruction is applicable to quantitative ( 15) O PET study and is superior toĮvaluation of the default-mode network by quantitative 15 O-PET: comparative study between cerebral blood flow and oxygen consumption.Īoe, Jo Watabe, Tadashi Shimosegawa, Eku Kato, Hiroki Kanai, Yasukazu Naka, Sadahiro Matsunaga, Keiko Isohashi, Kayako Tatsumi, Mitsuaki Hatazawa, Jun Agreement of quantitative values between FBP and DRAMA was excellent. The sinogram bootstrap analysis revealed that DRAMA reconstruction resulted in less statistical noise, especially in a low-activity region compared to FBP.
Based on the count recovery data, N (it) = 3 was determined as an optimal parameter for ( 15) O PET data.
DRAMA images were post-filtered so that their spatial resolutions were matched with FBP images with a 6-mm FWHM Gaussian filter. Once the optimal N (it) was determined, statistical image noise and quantitative parameters, i.e., cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO(2)) and oxygen extraction fraction (OEF) were compared between DRAMA and conventional FBP. To estimate the statistical variance of reconstructed images on a pixel-by-pixel basis, a sinogram bootstrap method was applied using list-mode PET data. First, the number of main iterations (N (it)) in DRAMA was optimized in relation to image convergence and statistical image noise. The PET study included 3 sequential PET scans for C( 15) O, ( 15) O(2) and H (2) ( 15) O. Seventeen healthy volunteers were studied using a 3D PET scanner.
The aim of this study was to assess the capability of DRAMA reconstruction for quantitative ( 15) O brain positron emission tomography (PET). Ibaraki, Masanobu Sato, Kaoru Mizuta, Tetsuro Kitamura, Keishi Miura, Shuichi Sugawara, Shigeki Shinohara, Yuki Kinoshita, ToshibumiĪ modified version of row-action maximum likelihood algorithm (RAMLA) using a 'subset-dependent' relaxation parameter for noise suppression, or dynamic RAMLA (DRAMA), has been proposed. Evaluation of dynamic row-action maximum likelihood algorithm reconstruction for quantitative 15 O brain PET.
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