Engel H, Steinert H, Buck A, Berthold T, Huch Böni R A, von Schulthess G K
Department of Medical Radiology, University Hospital, Zürich, Switzerland.
J Nucl Med. 1996 Mar;37(3):441-6.
The purpose of this study was to semiquantitatively identify artifactual and physiological soft-tissue accumulations in whole-body FDG-PET scans with the aim of defining their frequency and anatomic distribution.
Fifty whole-body FDG-PET scans performed for the staging of malignant melanoma were obtained from transaxial scans and reconstructed without absorption correction by filtered backprojection in the form of coronal and sagittal sections. The patients were asked to stay n.p.o. for at least 4 hr and interrogated about their physical activity prior to injection and until scanning. Classification of FDG organ accumulations was done using grades 0-6. Means and standard deviations on this scale were then calculated for multiple organs and muscle groups and tabulated.
On this grading scale, viscera showed uptake grades between 1.7 +/- 0.5 and 2.05 +/- 1.0. Except for the intestines, the activity in these organs was homogeneously distributed. Relatively high average uptake values of 2.0-4.2 (s.d. > or = 2.3) were found in various muscle groups, especially the orbital musculature. Myocardial uptake was visible in 90% of the scans. Reconstruction artifacts were seen around the renal collecting system and the bladder.
Most of the "normal" accumulations of FDG in nonattenuation corrected whole-body PET are readily recognized and distinct from the usually focal FDG accumulation associated with metastatic disease, but the diagnostician must be familiar with them. Muscular FDG uptake is related to physical activity prior and immediately following injection and can be minimized by proper patient instructions and positioning.
本研究的目的是在全身FDG - PET扫描中半定量识别伪影和生理性软组织积聚，以确定其频率和解剖分布。
从轴位扫描中获取50例用于恶性黑色素瘤分期的全身FDG - PET扫描图像，并通过滤波反投影重建为冠状面和矢状面图像，重建过程中未进行吸收校正。要求患者至少禁食4小时，并询问其注射前直至扫描时的身体活动情况。使用0 - 6级对FDG在器官中的积聚进行分类。然后计算多个器官和肌肉群在该分级量表上的均值和标准差，并制成表格。
在该分级量表上，内脏的摄取等级在1.7±0.5至2.05±1.0之间。除肠道外，这些器官中的活性分布均匀。在不同肌肉群，尤其是眼眶肌肉组织中发现相对较高的平均摄取值为2.0 - 4.2（标准差≥2.3）。90%的扫描图像可见心肌摄取。在肾集合系统和膀胱周围可见重建伪影。
在未进行衰减校正的全身PET中，大多数FDG的“正常”积聚易于识别，且与通常与转移性疾病相关的局灶性FDG积聚不同，但诊断医生必须熟悉它们。肌肉FDG摄取与注射前及注射后即刻的身体活动有关，通过适当的患者指导和体位摆放可将其降至最低。
