Departments of Radiology and Nuclear Medicine, Hammersmith Hospital, Imperial College Healthcare NHS Trust, Du Cane Road, London, W12 0HS, UK.
Department of Clinical Oncology, Hammersmith Hospital, Imperial College Healthcare NHS Trust, Du Cane Road, London, W12 0HS, UK.
Eur J Nucl Med Mol Imaging. 2021 Jun;48(6):2009-2023. doi: 10.1007/s00259-020-05136-8. Epub 2020 Dec 11.
Cervical cancer metabolic tumour volume (MTV) derived from [18F]-FDG PET/CT has a role in prognostication and therapy planning. There is no standard method of outlining MTV on [18F]-FDG PET/CT. The aim of this study was to assess the optimal method to outline primary cervical tumours on [18F]-FDG PET/CT using MRI-derived tumour volumes as the reference standard.
81 consecutive cervical cancer patients with pre-treatment staging MRI and [18F]-FDG PET/CT imaging were included. MRI volumes were compared with different PET segmentation methods. Method 1 measured MTVs at different SUV thresholds ranging from 20 to 60% (MTV-MTV) with bladder masking and manual adjustment when required. Method 2 created an isocontour around the tumour prior to different SUV thresholds being applied. Method 3 used an automated gradient method. Inter-observer agreement of MTV, following manual adjustment when required, was recorded.
For method 1, the MTV and MTV were closest to the MRI volumes for both readers (mean percentage change from MRI volume of 2.9% and 13.4% for MTV and - 13.1% and - 2.0% for MTV for readers 1 and 2). 70% of lesions required manual adjustment at MTV compared with 45% at MTV. There was excellent inter-observer agreement between MTV to MTV (ICC ranged from 0.898-0.976 with narrow 95% confidence intervals (CIs)) and moderate agreement at lower thresholds (ICC estimates of 0.534 and 0.617, respectively for the MTV and MTV with wide 95% CIs). Bladder masking was performed in 86% of cases overall. For method 2, excellent correlation was demonstrated at MTV and MTV (mean % change from MRI volume of -3.9% and - 8.6% for MTV and - 16.9% and 19% for MTV for readers 1 and 2, respectively). This method also demonstrated excellent ICC across all thresholds with no manual adjustment. Method 3 demonstrated excellent ICC of 0.96 (95% CI 0.94-0.97) but had a mean percentage difference from the MRI volume of - 19.1 and - 18.2% for readers 1 and 2, respectively. 21% required manual adjustment for both readers.
MTV provides the optimal correlation with MRI volume taking into consideration the excellent inter-reader agreement and less requirement for manual adjustment.
源于[18F]-FDG PET/CT 的宫颈癌代谢肿瘤体积（MTV）在预测和治疗计划中具有作用。目前尚无在[18F]-FDG PET/CT 上勾画 MTV 的标准方法。本研究旨在评估使用 MRI 衍生的肿瘤体积作为参考标准，通过[18F]-FDG PET/CT 勾画原发性宫颈癌肿瘤的最佳方法。
纳入了 81 例接受治疗前分期 MRI 和[18F]-FDG PET/CT 成像的宫颈癌患者。将 MRI 体积与不同的 PET 分割方法进行比较。方法 1 测量了 SUV 阈值范围为 20%至 60%（MTV-MTV）的不同 MTVs，当需要时使用膀胱掩模和手动调整。方法 2 在应用不同 SUV 阈值之前创建肿瘤的等轮廓。方法 3 使用自动梯度方法。记录了在需要时进行手动调整后的 MTV 的观察者间一致性。
对于方法 1，对于两位读者来说，MTV 和 MTV 最接近 MRI 体积（读者 1 和 2 的 MTV 从 MRI 体积的百分比变化分别为 2.9%和 13.4%，而 MTV 的百分比变化分别为-13.1%和-2.0%）。与 MTV 相比，70%的病变需要手动调整，而 MTV 则需要 45%的病变需要手动调整。在 MTV 到 MTV 之间，观察者间一致性极好（ICC 范围为 0.898-0.976，95%置信区间（CI）较窄），而在较低阈值下一致性适度（对于 MTV 和 MTV，ICC 估计值分别为 0.534 和 0.617，95%CI 较宽）。总体而言，在 86%的情况下进行了膀胱掩模。对于方法 2，在 MTV 和 MTV 中显示出极好的相关性（读者 1 和 2 的 MTV 从 MRI 体积的平均百分比变化分别为-3.9%和-8.6%，而 MTV 的百分比变化分别为-16.9%和 19%）。该方法还在所有阈值下均表现出极好的 ICC，无需手动调整。方法 3 显示出极好的 ICC 为 0.96（95%CI 0.94-0.97），但与 MRI 体积的平均百分比差异分别为读者 1 和 2 的-19.1%和-18.2%。两位读者均有 21%的病例需要手动调整。
考虑到优秀的读者间一致性和较少的手动调整需求，MTV 与 MRI 体积的相关性最佳。
