Tahari Abdel K, Lodge Martin A, Wahl Richard L
Nuclear Medicine Division, Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
J Med Imaging Radiat Oncol. 2014;58(3):277-82. doi: 10.1111/1754-9485.12154. Epub 2014 Jan 20.
Respiratory motion degrades fluorodeoxyglucose positron emission tomography (FDG PET) images of the lower chest and upper abdomen, as the blur introduced by breathing motion increases the apparent size of the moving tumour lesions and decreases their apparent uptake, reducing the sensitivity of PET in detection of small lesions. We assessed the role of delayed and respiratory-gated PET acquisition in the quantitative evaluation of lung and liver lesions.
A retrospective analysis of 64 lesions was performed. After initial non-gated whole-body PET/CT, respiratory gating was performed with 15 min in list mode. Non-gated delayed images were obtained by summing all list mode data. SUV(max) adjusted for lean body mass (SUL(max)) was measured in the initial whole-body scan, the delayed non-gated scans and the individual gated bins for each lesion. The axial z-position of SUL(max) for each lesion in five respiratory-gated bins was determined. The mean SUL of the non-pathological liver parenchyma was also recorded for each patient.
Tumour lesion SUL(max) increased by an average of 34% in the delayed non-gated scan as compared with the whole-body initial scan and further by an additional 17.2% in respiratory-gated images. The maximum lesion displacement was 6.2 ± 5.0 mm.
Delayed imaging alone substantially increases the magnitude of the SUL of liver and lung lesions as compared with standard whole-body images and may allow for a more accurate definition of the lesion's volume and localisation and improve tracer quantitation in malignant lesions in the lungs or upper abdomen. While respiratory gating provides more optimal imaging with greatest increase in SUL(max), the benefit is small, and delayed imaging appears sufficient in most cases.
呼吸运动会使下胸部和上腹部的氟脱氧葡萄糖正电子发射断层扫描（FDG PET）图像质量下降，因为呼吸运动引入的模糊会增加移动肿瘤病灶的表观大小，并降低其表观摄取，从而降低PET检测小病灶的灵敏度。我们评估了延迟和呼吸门控PET采集在肺和肝病灶定量评估中的作用。
对64个病灶进行回顾性分析。在初始非门控全身PET/CT检查后，以列表模式进行15分钟的呼吸门控。通过对所有列表模式数据求和获得非门控延迟图像。在初始全身扫描、延迟非门控扫描以及每个病灶的各个门控区间中测量经瘦体重校正的SUV（最大值）（SUL（最大值））。确定每个病灶在五个呼吸门控区间中SUL（最大值）的轴向z位置。还记录了每位患者非病理性肝实质的平均SUL。
与全身初始扫描相比，延迟非门控扫描中肿瘤病灶的SUL（最大值）平均增加了34%，在呼吸门控图像中进一步增加了17.2%。病灶最大位移为6.2±5.0毫米。
与标准全身图像相比，仅延迟成像就显著增加了肝和肺病灶的SUL值，可能有助于更准确地定义病灶体积和定位，并改善肺部或上腹部恶性病灶的示踪剂定量。虽然呼吸门控提供了更优化的成像，SUL（最大值）增加最大，但益处较小，在大多数情况下延迟成像似乎就足够了。
