Saleem Ben R, Beukinga Roelof J, Boellaard Ronald, Glaudemans Andor W J M, Reijnen Michel M P J, Zeebregts Clark J, Slart Riemer H J A
Department of Surgery, Division of Vascular Surgery, University of Groningen, University Medical Center Groningen, P.O. Box 30 001, 9700 RB, Groningen, The Netherlands.
Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Eur J Nucl Med Mol Imaging. 2017 May;44(5):886-894. doi: 10.1007/s00259-016-3599-7. Epub 2016 Dec 24.
The clinical problem in suspected aortoiliac graft infection (AGI) is to obtain proof of infection. Although F-fluorodeoxyglucose (F-FDG) positron emission tomography scanning (PET) has been suggested to play a pivotal role, an evidence-based interpretation is lacking. The objective of this retrospective study was to examine the feasibility and utility of F-FDG uptake heterogeneity characterized by textural features to diagnose AGI.
Thirty patients with a history of aortic graft reconstruction who underwent F-FDG PET/CT scanning were included. Sixteen patients were suspected to have an AGI (group I). AGI was considered proven only in the case of a positive bacterial culture. Positive cultures were found in 10 of the 16 patients (group Ia), and in the other six patients, cultures remained negative (group Ib). A control group was formed of 14 patients undergoing F-FDG PET for other reasons (group II). PET images were assessed using conventional maximal standardized uptake value (SUVmax), tissue-to-background ratio (TBR), and visual grading scale (VGS). Additionally, 64 different F-FDG PET based textural features were applied to characterize F-FDG uptake heterogeneity. To select candidate predictors, univariable logistic regression analysis was performed (α = 0.16). The accuracy was satisfactory in case of an AUC > 0.8.
The feature selection process yielded the textural features named variance (AUC = 0.88), high grey level zone emphasis (AUC = 0.87), small zone low grey level emphasis (AUC = 0.80), and small zone high grey level emphasis (AUC = 0.81) most optimal for distinguishing between groups I and II. SUVmax, TBR, and VGS were also able to distinguish between these groups with AUCs of 0.87, 0.78, and 0.90, respectively. The textural feature named short run high grey level emphasis was able to distinguish group Ia from Ib (AUC = 0.83), while for the same task the TBR and VGS were not found to be predictive. SUVmax was found predictive in distinguishing these groups, but showed an unsatisfactory accuracy (AUC = 0.75).
Textural analysis to characterize F-FDG uptake heterogeneity is feasible and shows promising results in diagnosing AGI, but requires additional external validation and refinement before it can be implemented in the clinical decision-making process.
疑似主-髂动脉移植物感染（AGI）的临床问题在于获取感染证据。尽管已有人提出氟脱氧葡萄糖（F-FDG）正电子发射断层扫描（PET）可发挥关键作用，但缺乏基于证据的解读。这项回顾性研究的目的是检验以纹理特征表征的F-FDG摄取异质性在诊断AGI中的可行性和实用性。
纳入30例有主动脉移植物重建病史且接受F-FDG PET/CT扫描的患者。16例患者疑似患有AGI（I组）。仅在细菌培养呈阳性的情况下AGI才被视为确诊。16例患者中有10例培养结果为阳性（Ia组），另外6例患者培养结果为阴性（Ib组）。对照组由14例因其他原因接受F-FDG PET检查的患者组成（II组）。使用传统的最大标准化摄取值（SUVmax）、组织与本底比值（TBR）和视觉分级量表（VGS）对PET图像进行评估。此外，应用64种基于F-FDG PET的不同纹理特征来表征F-FDG摄取异质性。为选择候选预测指标，进行了单变量逻辑回归分析（α = 0.16）。在曲线下面积（AUC）> 0.8时准确性令人满意。
特征选择过程得出了名为方差（AUC = 0.88）、高灰度级区域强调（AUC = 0.87）、小区域低灰度级强调（AUC = 0.80）和小区域高灰度级强调（AUC = 0.81）的纹理特征，这些特征在区分I组和II组时最为理想。SUVmax、TBR和VGS也能够区分这两组，其AUC分别为0.87、0.78和0.90。名为短程高灰度级强调的纹理特征能够区分Ia组和Ib组（AUC = 0.83），而对于同样的任务，未发现TBR和VGS具有预测性。发现SUVmax在区分这些组时具有预测性，但准确性不令人满意（AUC = 0.75）。
以纹理分析表征F-FDG摄取异质性在诊断AGI中是可行的，且显示出有前景的结果，但在可应用于临床决策过程之前，需要额外的外部验证和完善。
