Martin Geoffrey V, Kudchadker Rajat J, Bruno Teresa L, Frank Steven J, Wang Jihong
Division of Radiation Oncology, Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX.
Brachytherapy. 2018 Mar-Apr;17(2):298-305. doi: 10.1016/j.brachy.2017.09.014. Epub 2017 Nov 21.
To study the deformation of the prostate by a rigid reusable endorectal coil and a balloon-type endorectal coil (BTC) during MRI of the prostate in brachytherapy imaging.
The prostate gland was contoured on 157 MRI scans from 52 prostate cancer patients undergoing brachytherapy. The curvature of the posterior prostate surface deformation was computed as a measure of prostate distortion and compared between scans with a BTC, rigid endorectal coil (REC), or no endorectal coil. For the nine patients who had MRIs with all three endorectal scenarios, a mean prostate deformation vector was also calculated between scenarios using deformable image registration. These measures of prostate distortion were compared with the prostate anterior-to-posterior to left-to-right ratio (AP/LR) on the largest prostate axial slice.
Significant differences in prostate curvature were found between scans without an endorectal coil versus a REC versus a BTC (p < 0.001). The mean prostate deformation was 3.9 mm due to the BTC and 2.0 mm for the REC (p = 0.012). The mean AP/LR ratio was 0.62 with a BTC versus 0.76 without a coil or 0.73 with a REC (p < 0.001), but no difference existed between scans with a REC versus no coil (p = 0.7). The AP/LR ratio showed moderate correlation with prostate curvature (r = 0.48), and with mean prostate deformation (r = -0.64 to 0.68).
The REC caused minimal deformation of the prostate compared with a BTC with adequate MR image quality, and calculation of the cross-sectional AP/LR ratio on the largest axial prostate slice can serve as a simple measure of prostate distortion.
研究在近距离放射治疗成像的前列腺MRI检查过程中，刚性可重复使用的直肠内线圈和球囊型直肠内线圈（BTC）对前列腺的变形情况。
对52例接受近距离放射治疗的前列腺癌患者的157次MRI扫描图像上的前列腺进行轮廓勾画。计算前列腺后表面变形的曲率，作为前列腺变形的一种度量，并在使用BTC、刚性直肠内线圈（REC）或不使用直肠内线圈的扫描之间进行比较。对于9例接受了所有三种直肠内线圈扫描方案的患者，还使用可变形图像配准计算了不同方案之间的平均前列腺变形向量。将这些前列腺变形的度量与最大前列腺轴位切片上的前列腺前后径与左右径之比（AP/LR）进行比较。
未使用直肠内线圈、使用REC和使用BTC的扫描之间，前列腺曲率存在显著差异（p < 0.001）。BTC导致的平均前列腺变形为3.9毫米，REC为2.0毫米（p = 0.012）。使用BTC时的平均AP/LR比值为0.62，不使用线圈时为0.76，使用REC时为0.73（p < 0.001），但使用REC的扫描与不使用线圈的扫描之间无差异（p = 0.7）。AP/LR比值与前列腺曲率呈中度相关（r = 0.48），与平均前列腺变形呈中度相关（r = -0.64至0.68）。
与BTC相比，REC在获得足够的MR图像质量时对前列腺造成的变形最小，并且在最大的前列腺轴位切片上计算横截面AP/LR比值可作为前列腺变形的一种简单度量方法。
