Institute of Medical Physics, School of Physics, Faculty of Science, The University of Sydney, Sydney, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia.
Institute of Medical Physics, School of Physics, Faculty of Science, The University of Sydney, Sydney, NSW, Australia.
Magn Reson Imaging. 2021 Apr;77:169-179. doi: 10.1016/j.mri.2020.12.018. Epub 2021 Jan 1.
Quantitative MRI (qMRI) parameters have been increasingly used to develop predictive models to accurately monitor treatment response in prostate cancer after radiotherapy. To reliably detect changes in signal due to treatment response, predictive models require qMRI parameters with high repeatability and reproducibility. The purpose of this study was to measure qMRI parameter uncertainties in both commercial and in-house developed phantoms to guide the development of robust predictive models for monitoring treatment response.
ADC, T1, and R2* values were acquired across three 3 T scanners with a prostate-specific qMRI protocol using the NIST/ISMRM system phantom, RSNA/NIST diffusion phantom, and an in-house phantom. A B1 field map was acquired to correct for flip angle inhomogeneity in T1 maps. All sequences were repeated in each scan to assess within-session repeatability. Weekly scans were acquired on one scanner for three months with the in-house phantom. Between-session repeatability was measured with test-retest scans 6-months apart on all scanners with all phantoms. Accuracy, defined as percentage deviation from reference value for ADC and T1, was evaluated using the system and diffusion phantoms. Repeatability and reproducibility coefficients of variation (%CV) were calculated for all qMRI parameters on all phantoms.
Overall, repeatability CV of ADC was <2.40%, reproducibility CV was <3.98%, and accuracy ranged between -8.0% to 2.7% across all scanners. Applying B1 correction on T1 measurements significantly improved the repeatability and reproducibility (p<0.05) but increased error in accuracy (p<0.001). Repeatability and reproducibility of R2* was <4.5% and <7.3% respectively in the system phantom across all scanners.
Repeatability, reproducibility, and accuracy in qMRI parameters from a prostate-specific protocol was estimated using both commercial and in-house phantoms. Results from this work will be used to identify robust qMRI parameters for use in the development of predictive models to longitudinally monitor treatment response for prostate cancer in current and future clinical trials.
定量磁共振成像（qMRI）参数已被越来越多地用于开发预测模型，以准确监测前列腺癌放射治疗后的治疗反应。为了可靠地检测到治疗反应引起的信号变化，预测模型需要具有高重复性和可再现性的 qMRI 参数。本研究的目的是测量商业和内部开发的体模中的 qMRI 参数不确定性，以指导用于监测治疗反应的稳健预测模型的开发。
使用前列腺特异性 qMRI 方案，在三台 3T 扫描仪上采集 ADC、T1 和 R2* 值，该方案使用了 NIST/ISMRM 系统体模、RSNA/NIST 扩散体模和内部体模。采集 B1 场图以校正 T1 图中的翻转角不均匀性。所有序列在每次扫描中重复以评估会话内的可重复性。在一台扫描仪上进行为期三个月的每周扫描，使用内部体模。使用所有体模在所有扫描仪上进行 6 个月的测试-再测试扫描，以测量会话间的可重复性。使用系统和扩散体模评估 ADC 和 T1 的参考值的偏差百分比，以评估准确性。计算所有体模上所有 qMRI 参数的重复性和再现性变异系数（%CV）。
总体而言，ADC 的重复性 CV 小于 2.40%，再现性 CV 小于 3.98%，在所有扫描仪上的准确性范围为-8.0%至 2.7%。在 T1 测量中应用 B1 校正显著提高了重复性和再现性（p<0.05），但增加了准确性的误差（p<0.001）。在所有扫描仪上，系统体模中 R2* 的重复性和再现性分别小于 4.5%和 7.3%。
使用商业和内部体模估计了前列腺特异性方案中的 qMRI 参数的重复性、再现性和准确性。本工作的结果将用于确定稳健的 qMRI 参数，以用于开发预测模型，用于在当前和未来的临床试验中对前列腺癌的治疗反应进行纵向监测。
