Ahlman Mark A, Vigneault Davis M, Sandfort Veit, Maass-Moreno Roberto, Dave Jenny, Sadek Ahmed, Mallek Marissa B, Selwaness Mariana A F, Herscovitch Peter, Mehta Nehal N, Bluemke David A
Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States of America.
Institute of Biomedical Engineering, Department of Engineering, University of Oxford, Oxford, United Kingdom.
PLoS One. 2017 Nov 13;12(11):e0187995. doi: 10.1371/journal.pone.0187995. eCollection 2017.
18Fluorodeoxyglucose (FDG) positron emission tomography (PET) uptake in the artery wall correlates with active inflammation. However, in part due to the low spatial resolution of PET, variation in the apparent arterial wall signal may be influenced by variation in blood FDG activity that cannot be fully corrected for using typical normalization strategies. The purpose of this study was to evaluate the ability of the current common methods to normalize for blood activity and to investigate alternative methods for more accurate quantification of vascular inflammation.
The relationship between maximum FDG aorta wall activity and mean blood activity was evaluated in 37 prospectively enrolled subjects aged 55 years or more, treated for hyperlipidemia. Target maximum aorta standardized uptake value (SUV) and mean background reference tissue activity (blood, spleen, liver) were recorded. Target-to-background ratios (TBR) and arterial maximum activity minus blood activity were calculated. Multivariable regression was conducted, predicting uptake values based on variation in background reference and target tissue FDG uptake; adjusting for gender, age, lean body mass (LBM), blood glucose, blood pool activity, and glomerular filtration rate (GFR), where appropriate.
Blood pool activity was positively associated with maximum artery wall SUV (β = 5.61, P<0.0001) as well as mean liver (β = 6.23, P<0.0001) and spleen SUV (β = 5.20, P<0.0001). Artery wall activity divided by blood activity (TBRBlood) or subtraction of blood activity did not remove the statistically significant relationship to blood activity. Blood pool activity was not related to TBRliver and TBRspleen (β = -0.36, P = NS and β = -0.58, P = NS, respectively).
In otherwise healthy individuals treated for hyperlipidemia, blood FDG activity is associated with artery wall activity. However, variation in blood activity may mask artery wall signal reflective of inflammation, which requires normalization. Blood-based TBR and subtraction do not sufficiently adjust for blood activity. Warranting further investigation, background reference tissues with cellular uptake such as the liver and spleen may better adjust for variation in blood activity to improve assessment of vascular activity.
动脉壁中的18氟脱氧葡萄糖（FDG）正电子发射断层扫描（PET）摄取与活动性炎症相关。然而，部分由于PET的空间分辨率较低，动脉壁表观信号的变化可能受到血液FDG活性变化的影响，而使用典型的归一化策略无法完全校正这种影响。本研究的目的是评估当前常用方法对血液活性进行归一化的能力，并研究更准确量化血管炎症的替代方法。
在37名年龄55岁及以上、接受高脂血症治疗的前瞻性入组受试者中，评估了最大FDG主动脉壁活性与平均血液活性之间的关系。记录目标最大主动脉标准化摄取值（SUV）和平均背景参考组织活性（血液、脾脏、肝脏）。计算目标与背景比值（TBR）以及动脉最大活性减去血液活性。进行多变量回归，根据背景参考和目标组织FDG摄取的变化预测摄取值；在适当情况下，对性别、年龄、瘦体重（LBM）、血糖、血池活性和肾小球滤过率（GFR）进行调整。
血池活性与最大动脉壁SUV呈正相关（β = 5.61，P<0.0001），与平均肝脏SUV（β = 6.23，P<0.0001）和脾脏SUV（β = 5.20，P<0.0001）也呈正相关。动脉壁活性除以血液活性（TBRBlood）或减去血液活性并不能消除与血液活性的统计学显著关系。血池活性与TBRliver和TBRspleen无关（β = -0.36，P = 无统计学意义和β = -0.58，P = 无统计学意义）。
在接受高脂血症治疗的其他方面健康的个体中，血液FDG活性与动脉壁活性相关。然而，血液活性的变化可能掩盖反映炎症的动脉壁信号，这需要进行归一化。基于血液的TBR和减法不能充分调整血液活性。值得进一步研究的是，具有细胞摄取功能的背景参考组织，如肝脏和脾脏，可能更好地调整血液活性的变化，以改善对血管活性的评估。
