Qi Zhihua, Gates Erica L, O'Brien Maureen M, Trout Andrew T
Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45243, USA.
Division of Oncology, Cancer and Blood Disease Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
Pediatr Radiol. 2018 Feb;48(2):196-203. doi: 10.1007/s00247-017-4019-2. Epub 2017 Oct 28.
Both [F-18]2-fluoro-2-deoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) and diagnostic CT are at times required for lymphoma staging. This means some body segments are exposed twice to X-rays for generation of CT data (diagnostic CT + localization CT).
To describe a combined PET/diagnostic CT approach that modulates CT tube current along the z-axis, providing diagnostic CT of some body segments and localization CT of the remaining body segments, thereby reducing patient radiation dose.
We retrospectively compared total patient radiation dose between combined PET/diagnostic CT and separately acquired PET/CT and diagnostic CT exams. When available, we calculated effective doses for both approaches in the same patient; otherwise, we used data from patients of similar size. To confirm image quality, we compared image noise (Hounsfield unit [HU] standard deviation) as measured in the liver on both combined and separately acquired diagnostic CT images. We used t-tests for dose comparisons and two one-sided tests for image-quality equivalence testing.
Mean total effective dose for the CT component of the combined and separately acquired diagnostic CT exams were 6.20±2.69 and 8.17±2.61 mSv, respectively (P<0.0001). Average dose savings with the combined approach was 24.8±17.8% (2.60±2.51 mSv [range: 0.32-4.72 mSv]) of total CT effective dose. Image noise was not statistically significantly different between approaches (12.2±1.8 HU vs. 11.7±1.5 HU for the combined and separately acquired diagnostic CT images, respectively).
A combined PET/diagnostic CT approach as described offers dose savings at similar image quality for children and young adults with lymphoma who have indications for both PET and diagnostic CT examinations.
淋巴瘤分期有时需要同时进行[F-18]2-氟-2-脱氧葡萄糖正电子发射断层扫描/计算机断层扫描（F-FDG PET/CT）和诊断性CT。这意味着身体的某些部位会两次暴露于X射线下以生成CT数据（诊断性CT + 定位CT）。
描述一种PET/诊断性CT联合检查方法，该方法可沿z轴调节CT管电流，对身体的某些部位进行诊断性CT检查，对其余身体部位进行定位CT检查，从而降低患者的辐射剂量。
我们回顾性比较了PET/诊断性CT联合检查与单独进行PET/CT和诊断性CT检查时患者的总辐射剂量。如有可能，我们计算了同一患者两种检查方法的有效剂量；否则，我们使用了体型相似患者的数据。为确认图像质量，我们比较了联合检查和单独获取的诊断性CT图像上肝脏的图像噪声（亨氏单位[HU]标准差）。我们使用t检验进行剂量比较，使用双侧单侧检验进行图像质量等效性测试。
联合检查和单独进行诊断性CT检查的CT部分的平均总有效剂量分别为6.20±2.69和8.17±2.61 mSv（P<0.0001）。联合检查方法平均节省的剂量为CT总有效剂量的24.8±17.8%（2.60±2.51 mSv[范围：0.32 - 4.72 mSv]）。两种检查方法的图像噪声在统计学上无显著差异（联合检查和单独获取的诊断性CT图像的图像噪声分别为12.2±1.8 HU和11.7±1.5 HU）。
所述的PET/诊断性CT联合检查方法可为有PET和诊断性CT检查指征的淋巴瘤儿童和青年患者在图像质量相似的情况下节省剂量。
