论文题目：A system-level analysis of Total-body PET data reveals complex skeletal metabolism networks in vivo
笔记：陈亦新
本文分析方法简单，不错的文章。
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introduction
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The availability of large in vitro cell and tissue omic datasets and bioinformatic tools have equipped researchers to understand molecular processes that cause disease, and identify and develop new therapeutics. However, novel systems approaches are needed to understand complex in vivo physiological and pathological interactions at multi-tissue level.
prior to PET/CT imaging,mice were weighed,用预先设置的0.5/0.5 L/min的oxygen/nitrous oxide and 3% isoflurane异氟烷混合物麻醉，并移动到microPET/CT
扫描仪。整个PET/CT起劲啊，患者保持全身麻醉，并在实验过程检测生命体征、包括温度和呼吸频率。动物接收静脉注射的18F-FDG。18F-FDG was produces in-house (Edinburgh Imaging) using standard methods or radiolabelling.
下面介绍PET的protocal。注射放射性示踪剂之后，动物立刻进行全身扫描，随后进行CT扫描。收集到的PET图像便使用CT数据进行衰减矫正。PET image在0~60min之间重建，protocal为6x30,3x60,2x120,10x300frame，using Mediso's iterative Tetra-tomo 3D reconstruction algorithm.
The following settings: four iterations, six subsets, full detector model, low regularisation, spike fifilter on, voxel size 0.4 mm and 400-600 keV energy window. PET data were corrected for random coincidences, scatter, and attenuation.
Image Processing and Standard Uptake Value Calculation
重建后的图像使用PMOD3.7的软件进行分析。在胫骨、股骨、肱骨、桡骨和尺骨（前臂）、脊柱、胸骨和颅骨周围绘制了感兴趣的体积（VOI）。为了区别骨组织和骨髓和周围的组织，VOL使用事先定义的Hounsfield Unit HU。（332-50000）generated using HU obtained from the acquisition of a CT tissue equivalent material phantom.
然后对所有动态PET数据进行从扫描开始到注射放射性示踪剂时间的时间延迟矫正。Time activity curves were generated and standard uptake values were calculated by normalising radioactive concentration in VOI for the injected dose and the animal weight.
这一段没有理解全：
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Networks Analisis of Total-body PET Data
非衰减矫正的动态全身PET数据被汇总成了一个csv表，其中行表示小鼠单个骨骼的平均18F-FDG信号,列是记录的时间信号。文件被保存在csv文件中。计算了Pearson correlations系数，然后我们可以得到一个relationship matrix graph，通过相关系数R>0.7和k-nearest neighbours KNN of 3。通过最小化边缘的数量，组织积累档案之间的关系结构可以被揭示，反应在graph的结构和边缘的权重当中。节点表示每一个骨头，edge表示大于选定阈值的相关性。阈值被设置成所有可用数据都有相同的节点数量
Statistical Analysis, Data Presentation, and Reproducibility
Murine Bone Density to energy metabolism quotient diversity identified by WB-PET/CT analysis
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上图A就是CT和PET的图像。
BCD图是Hounsfield units和standard uptake values值.SUV was calculated by averaging mouse dynamic PET time-activity curves between 45 and 60 min post-injection into a single static data point for each bone. SUV对于每一个小鼠的每一个骨头来说是一个static的值。
box-and-whisker plots：boxes indicate the 25th and 75th percentiles；whisker display the range; and horizontal lines in each box represent the median.
Significant diffeneces were determined by a one-way ANOVA with multiple comparisons. Different symbols above the error bar show significant difference at P < 0.05
Murine Bone Energy Metabolism Network Identified by Dynamic Total-Body PET/CT Analysis Shows Spine Density Has Strongest Dependence on Glucose Metabolism.
