Wickham Fred, McMeekin Helena, Burniston Maria, McCool Daniel, Pencharz Deborah, Skillen Annah, Wagner Thomas
Nuclear Medicine Department, Royal Free London NHS Foundation Trust, Pond Street, London, NW3 2QG, UK.
Hermes Medical Solutions, 22 Long Acre, London, WC2E 9LY, UK.
EJNMMI Res. 2017 Dec;7(1):3. doi: 10.1186/s13550-016-0250-3. Epub 2017 Jan 13.
The purpose of this study is to identify a method for optimising the administered activity and acquisition time for F-FDG PET imaging, yielding images of consistent quality for patients with varying body sizes and compositions, while limiting radiation doses to patients and staff. Patients referred for FDG scans had bioimpedance measurements. They were injected with 3 MBq/kg of F up to 370 MBq and scanned on a Siemens Biograph mCT at 3 or 4 min per bed position. Data were rebinned to simulate 2- and 1-min acquisitions. Subjective assessments of image quality made by an experienced physician were compared with objective measurements based on signal-to-noise ratio and noise equivalent counts (NEC). A target objective measure of image quality was identified. The activity and acquisition time required to achieve this were calculated for each subject. Multiple regression analysis was used to identify expressions for the activity and acquisition time required in terms of easily measurable patient characteristics.
One hundred and eleven patients were recruited, and subjective and objective assessments of image quality were compared for 321 full and reduced time scans. NEC-per-metre was identified as the objective measure which best correlated with the subjective assessment (Spearman rank correlation coefficient 0.77) and the best discriminator for images with a subjective assessment of "definitely adequate" (area under the ROC curve 0.94). A target of 37 Mcount/m was identified. Expressions were identified in terms of patient sex, height and weight for the activity and acquisition time required to achieve this target. Including measurements of body composition in these expressions was not useful. Using these expressions would reduce the mean activity administered to this patient group by 66 MBq compared to the current protocol.
Expressions have been identified for the activity and acquisition times required to achieve consistent image quality in FDG imaging with reduced patient and staff doses. These expressions might need to be adapted for other systems and reconstruction protocols.
本研究的目的是确定一种优化F-FDG PET成像给药活度和采集时间的方法，为不同体型和身体成分的患者提供质量一致的图像，同时限制患者和工作人员所受的辐射剂量。接受FDG扫描的患者进行了生物电阻抗测量。他们按3 MBq/kg的剂量注射F，最高可达370 MBq，并在西门子Biograph mCT上以每个床位3或4分钟的时间进行扫描。数据重新分箱以模拟2分钟和1分钟的采集。将一位经验丰富的医生对图像质量的主观评估与基于信噪比和噪声等效计数（NEC）的客观测量进行比较。确定了图像质量的目标客观测量指标。计算了每个受试者达到该指标所需的活度和采集时间。采用多元回归分析确定根据易于测量的患者特征所需的活度和采集时间的表达式。
招募了111名患者，对321次全时和减时扫描的图像质量进行了主观和客观评估。每米NEC被确定为与主观评估相关性最佳的客观测量指标（斯皮尔曼等级相关系数为0.77），也是主观评估为“肯定足够”的图像的最佳判别指标（ROC曲线下面积为0.94）。确定了37 Mcount/m的目标。确定了根据患者性别、身高和体重达到该目标所需的活度和采集时间的表达式。在这些表达式中纳入身体成分测量并无帮助。与当前方案相比，使用这些表达式将使该患者组的平均给药活度降低66 MBq。
已确定在降低患者和工作人员剂量的情况下，在FDG成像中获得一致图像质量所需的活度和采集时间的表达式。这些表达式可能需要针对其他系统和重建方案进行调整。
