Evaluation of dynamic row-action maximum likelihood algorithm reconstruction for quantitative 15O brain PET

• Published in: Annals of nuclear medicine Vol. 23; no. 7; pp. 627 - 638
• Main Authors: Ibaraki, Masanobu, Sato, Kaoru, Mizuta, Tetsuro, Kitamura, Keishi, Miura, Shuichi, Sugawara, Shigeki, Shinohara, Yuki, Kinoshita, Toshibumi
• Format: Journal Article
• Language: English
• Published: Japan Springer Japan 01.09.2009; Springer Nature B.V
• Subjects: Aged; Algorithms; Brain - blood supply; Brain - diagnostic imaging; Brain - metabolism; Cerebrovascular Circulation; Female; Humans; Image Processing, Computer-Assisted - methods; Image Processing, Computer-Assisted - standards; Imaging; Likelihood Functions; Male; Medicine; Medicine & Public Health; Middle Aged; Nuclear Medicine; Original Article; Oxygen - metabolism; Oxygen Radioisotopes; Positron-Emission Tomography - methods; Positron-Emission Tomography - standards; Radiology; Reference Standards; Dynamic RAMLA; Oxygen metabolism; Iterative reconstruction; CBF; O PET
• ISSN: 0914-7187; 1864-6433
• DOI: 10.1007/s12149-009-0280-2

Objective A 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. The aim of this study was to assess the capability of DRAMA reconstruction for quantitative 15 O brain positron emission tomography (PET). Methods Seventeen healthy volunteers were studied using a 3D PET scanner. The PET study included 3 sequential PET scans for C 15 O, 15 O 2 and H 2 15 O. First, the number of main iterations ( N it ) in DRAMA was optimized in relation to image convergence and statistical image noise. 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. 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. DRAMA images were post-filtered so that their spatial resolutions were matched with FBP images with a 6-mm FWHM Gaussian filter. Results Based on the count recovery data, N it  = 3 was determined as an optimal parameter for 15 O PET data. The sinogram bootstrap analysis revealed that DRAMA reconstruction resulted in less statistical noise, especially in a low-activity region compared to FBP. Agreement of quantitative values between FBP and DRAMA was excellent. For DRAMA images, average gray matter values of CBF, CBV, CMRO 2 and OEF were 46.1 ± 4.5 (mL/100 mL/min), 3.35 ± 0.40 (mL/100 mL), 3.42 ± 0.35 (mL/100 mL/min) and 42.1 ± 3.8 (%), respectively. These values were comparable to corresponding values with FBP images: 46.6 ± 4.6 (mL/100 mL/min), 3.34 ± 0.39 (mL/100 mL), 3.48 ± 0.34 (mL/100 mL/min) and 42.4 ± 3.8 (%), respectively. Conclusion DRAMA reconstruction is applicable to quantitative 15 O PET study and is superior to conventional FBP in terms of image quality.