Maclean J, Fersht N, Sullivan K, Kayani I, Bomanji J, Dickson J, O'Meara C, Short S
University College London Hospitals NHS Trust, London, UK.
University College London Hospitals NHS Trust, London, UK.
Clin Oncol (R Coll Radiol). 2017 Jul;29(7):448-458. doi: 10.1016/j.clon.2017.03.004. Epub 2017 Apr 19.
The increasing use of highly conformal radiation techniques to treat meningioma confers a greater need for accurate targeting. Several groups have shown that positron emission tomography/computed tomography (PET/CT) information alters meningioma targets contoured by single observers, but whether this translates into improved accuracy has not been defined. As magnetic resonance imaging (MRI) is the cornerstone of meningioma target contouring, simultaneous PET/MRI may be superior to PET/CT. We assessed whether Ga DOTATATE PET imaging (from PET/CT and PET/MRI) reduced interobserver variability (IOV) in meningioma target volume contouring.
Ten patients with meningioma underwent simultaneous Ga DOTATATE PET/MRI followed by PET/CT. They were selected as it was anticipated that target volume definition in their cases would be particularly challenging. Three radiation oncologists contoured target volumes according to an agreed protocol: gross tumour volume (GTV) and clinical target volume (CTV) on CT/MRI alone, CT/MRI+PET(CT) and CT/MRI+PET(MRI). GTV/CTV Kouwenhoven conformity levels (KCL), regions of contour variation and qualitative differences between PET(CT) and PET(MRI) were evaluated.
There was substantial IOV in contouring. GTV mean KCL: CT/MRI 0.34, CT/MRI+PET(CT) 0.38, CT/MRI+PET(MRI) 0.39 (P = 0.06). CTV mean KCL: CT/MRI 0.31, CT/MRI+PET(CT) 0.35, CT/MRI+PET(MRI) 0.35 (P = 0.04 for all groups; P > 0.05 for individual pairs). One observer consistently contoured largest and one smallest. Observers rarely decreased volumes in relation to PET. Most IOV occurred in bone followed by dural tail, postoperative bed and venous sinuses. Tumour edges were qualitatively clearer on PET(MRI) versus PET(CT), but this did not affect contouring.
IOV in contouring challenging meningioma cases was large and only slightly improved with the addition of Ga DOTATATE PET. Simultaneous PET/MRI for meningioma contouring is feasible, but did not improve IOV versus PET/CT. Whether volumes can be safely reduced according to PET requires evaluation.
越来越多地使用高度适形放射技术治疗脑膜瘤，这使得对精确靶向的需求更大。多个研究小组表明，正电子发射断层扫描/计算机断层扫描（PET/CT）信息会改变由单一观察者勾勒出的脑膜瘤靶区，但这是否能转化为更高的准确性尚未明确。由于磁共振成像（MRI）是脑膜瘤靶区勾勒的基石，同时进行的PET/MRI可能优于PET/CT。我们评估了镓 DOTATATE PET成像（来自PET/CT和PET/MRI）是否能降低脑膜瘤靶区体积勾勒中的观察者间变异性（IOV）。
10例脑膜瘤患者先后接受了镓 DOTATATE PET/MRI和PET/CT检查。选择这些患者是因为预计他们病例中的靶区体积定义会特别具有挑战性。三位放射肿瘤学家根据商定的方案勾勒靶区体积：仅根据CT/MRI、CT/MRI + PET(CT)以及CT/MRI + PET(MRI)分别勾勒大体肿瘤体积（GTV）和临床靶区体积（CTV）。评估了GTV/CTV的考文霍夫适形水平（KCL）、轮廓变化区域以及PET(CT)和PET(MRI)之间的定性差异。
在勾勒过程中存在显著的IOV。GTV平均KCL：CT/MRI为0.34，CT/MRI + PET(CT)为0.38，CT/MRI + PET(MRI)为0.39（P = 0.06）。CTV平均KCL：CT/MRI为0.31，CT/MRI + PET(CT)为0.35，CT/MRI + PET(MRI)为0.35（所有组P = 0.04；各配对组P > 0.05）。一名观察者始终勾勒出最大的靶区，一名观察者始终勾勒出最小的靶区。观察者很少根据PET减少靶区体积。大多数IOV出现在骨骼部位，其次是硬脑膜尾、术后瘤床和静脉窦。与PET(CT)相比，PET(MRI)上肿瘤边缘在定性上更清晰，但这并未影响勾勒。
在勾勒具有挑战性的脑膜瘤病例时，IOV较大，添加镓 DOTATATE PET后仅略有改善。同时进行PET/MRI用于脑膜瘤勾勒是可行的，但与PET/CT相比，并未改善IOV。是否能根据PET安全地缩小靶区体积需要评估。
