Ibaraki Masanobu, Sato Kaoru, Mizuta Tetsuro, Kitamura Keishi, Miura Shuichi, Sugawara Shigeki, Shinohara Yuki, Kinoshita Toshibumi
Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita 010-0874, Japan.
Ann Nucl Med. 2009 Sep;23(7):627-38. doi: 10.1007/s12149-009-0280-2. Epub 2009 Jun 30.
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).
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.
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.
DRAMA reconstruction is applicable to quantitative (15)O PET study and is superior to conventional FBP in terms of image quality.
已提出一种改良版的行作用最大似然算法（RAMLA），即使用“子集相关”松弛参数进行噪声抑制的动态RAMLA（DRAMA）。本研究旨在评估DRAMA重建用于定量（15）O脑正电子发射断层扫描（PET）的能力。
使用3D PET扫描仪对17名健康志愿者进行研究。PET研究包括对C（15）O、（15）O（2）和H（2）（15）O进行3次连续的PET扫描。首先，针对图像收敛和统计图像噪声对DRAMA中的主要迭代次数（N（it））进行了优化。为了逐像素估计重建图像的统计方差，使用列表模式PET数据应用了正弦图自举法。一旦确定了最佳N（it），就比较了DRAMA和传统FBP之间的统计图像噪声和定量参数，即脑血流量（CBF）、脑血容量（CBV）、脑氧代谢率（CMRO（2））和氧摄取分数（OEF）。对DRAMA图像进行后滤波，使其空间分辨率与使用6毫米半高宽高斯滤波器的FBP图像相匹配。
基于计数恢复数据，确定N（it）= 3为（15）O PET数据的最佳参数。正弦图自举分析表明，与FBP相比，DRAMA重建产生的统计噪声更少，尤其是在低活性区域。FBP和DRAMA之间的定量值一致性良好。对于DRAMA图像，CBF、CBV、CMRO（2）和OEF的平均灰质值分别为46.1±4.5（mL/100 mL/min）、3.35±0.40（mL/100 mL）、3.42±0.35（mL/100 mL/min）和42.1±3.8（%）。这些值与FBP图像的相应值相当：分别为46.6±4.6（mL/100 mL/min）、3.34±0.39（mL/100 mL）、3.48±0.34（mL/100 mL/min）和42.4±3.8（%）。
DRAMA重建适用于定量（15）O PET研究，并且在图像质量方面优于传统FBP。
