Medical Radiation Physics, Lund, Lund University, Lund, Sweden.
Department of Clinical Sciences Lund, Oncology, Lund University, Lund, Sweden.
PLoS One. 2024 Jul 25;19(7):e0307558. doi: 10.1371/journal.pone.0307558. eCollection 2024.
Accurate tumor volume estimation is important for evaluating the response to radionuclide therapy and external beam radiotherapy as well as to other pharmaceuticals. A common method for monitoring the growth of subcutaneous tumors in pre-clinical models and assessing the treatment response is to measure the tumor length and width by external calipers to estimate its volume. This procedure relies on an assumption of a spheroidal tumor shape wherein the tumor depth equals the width and can yield considerably inaccuracies. Ultrasound imaging is a non-invasive technique that can measure all three axes of the tumor and might be an alternative to caliper measurement with potentially greater accuracy and comparable ease-of-use and throughput. Both 2D and 3D ultrasound imaging are possible, the former offering short scan times without the need for anesthesia and heating-valuable factors for longitudinal studies in large animal cohorts. Nevertheless, tumor volume estimation accuracy by 2D ultrasound imaging has seen limited investigation. In this study we have evaluated the accuracy of tumor volume estimation by caliper and 2D ultrasound with comparisons to reference measurements by magnetic resonance imaging (MRI) in a pre-clinical model of prostate cancer treated with either external beam radiotherapy, radionuclide therapy, or no treatment.
Tumor volumes were measured longitudinally in 29 mice by caliper, ultrasound, and MRI before and after external beam radiotherapy, [177Lu]Lu-PSMA-617 radionuclide therapy, or no treatment. Caliper measurements had a marked bias, overestimating the tumor volumes by a median of 150% compared to MRI. Ultrasound measurements were markedly more accurate, with a median bias of -21% compared to MRI.
Ultrasound imaging is a reliable and accurate method for tumor volume estimation in pre-clinical models of radiotherapy, whereas caliper measurements are prone to overestimation.
准确的肿瘤体积估测对于评估放射性核素治疗和外束放射治疗以及其他药物的疗效非常重要。在临床前模型中监测皮下肿瘤生长并评估治疗反应的常用方法是使用游标卡尺测量肿瘤的长度和宽度来估计其体积。该方法基于肿瘤形状为球形的假设，其中肿瘤的深度等于宽度，这可能会导致相当大的误差。超声成像是一种非侵入性技术，可以测量肿瘤的所有三个轴，并且可能是卡尺测量的替代方法，具有更高的准确性和类似的易用性和通量。二维和三维超声成像都是可能的，前者提供了较短的扫描时间，而无需麻醉和加热-这对于大型动物队列的纵向研究是有价值的因素。然而，二维超声成像的肿瘤体积估测准确性的研究有限。在这项研究中，我们评估了临床前前列腺癌模型中接受外束放射治疗、放射性核素治疗或未治疗的情况下，通过卡尺和二维超声与磁共振成像（MRI）参考测量值相比，肿瘤体积估测的准确性。
在接受外束放射治疗、[177Lu]Lu-PSMA-617 放射性核素治疗或未治疗之前和之后，通过卡尺、超声和 MRI 对 29 只小鼠进行了肿瘤体积的纵向测量。卡尺测量有明显的偏差，与 MRI 相比，平均高估了肿瘤体积的 150%。超声测量明显更准确，与 MRI 相比，平均偏差为-21%。
超声成像对于放射治疗的临床前模型中的肿瘤体积估测是一种可靠且准确的方法，而卡尺测量则容易高估。
