PDF(Pubmed)
Abstract：
Measuring left ventricular ejection fraction (LVEF) is important for detecting heart failure, e.g., in treatment with potentially cardiotoxic chemotherapy. MRI is considered the reference standard for LVEF, but availability may be limited and claustrophobia or metal implants still present challenges. CT has been shown to be accurate and would be advantageous, as LVEF could be measured in conjunction with routine chest-abdomen-pelvis oncology CT. However, the use of CT is not recommended due to the excessive radiation dose. This study aimed to explore the potential for dose reduction using simulation. Using an anthropomorphic heart phantom scanned at 13 dose levels, a noise simulation algorithm was developed to introduce controlled Poisson noise. Filtered backprojection parameters were iteratively tested to minimise differences in myocardium-to-ventricle contrast/noise ratio, as well as structural similarity index (SSIM) differences between real and simulated images at all dose levels. Fifty-one clinical CT coronary angiographies, scanned with full dose through end-systolic and -diastolic phases, were located retrospectively. Using the developed algorithm, noise was introduced corresponding to 25, 10, 5 and 2% of the original dose level. LVEF was measured using clinical software (Syngo.via VB50) with papillary muscles in and excluded from the LV volume. At each dose level, LVEF was compared to the 100% dose level, using Bland-Altman analysis. The effective dose was calculated from DLP using a conversion factor of 0.026 mSv/mGycm.
In the clinical images, mean CTDIvol and DLP were 47.1 mGy and 771.9 mGycm, respectively (effective dose 20.0 mSv). Measurements with papillary muscles excluded did not exhibit statistically significant LVEF bias to full-dose images at 25, 10 and 5% simulated dose. At 2% dose, a significant bias of 4.4% was found. With papillary muscles included, small but significant biases were found at all simulated dose levels.
Provided that measurements are performed with papillary muscles excluded from the LV volume, the dose can be reduced by a factor of 20 without significantly affecting LVEF measurements. This corresponds to an effective dose of 1 mSv. CT can potentially be used for LVEF measurement with minimal excessive radiation.
In the clinical images, mean CTDIvol and DLP were 47.1 mGy and 771.9 mGycm, respectively (effective dose 20.0 mSv). Measurements with papillary muscles excluded did not exhibit statistically significant LVEF bias to full-dose images at 25, 10 and 5% simulated dose. At 2% dose, a significant bias of 4.4% was found. With papillary muscles included, small but significant biases were found at all simulated dose levels.
Provided that measurements are performed with papillary muscles excluded from the LV volume, the dose can be reduced by a factor of 20 without significantly affecting LVEF measurements. This corresponds to an effective dose of 1 mSv. CT can potentially be used for LVEF measurement with minimal excessive radiation.
摘要：
背景：测量左心室射血分数（LVEF）对于检测心力衰竭很重要，例如，用潜在的心脏毒性化疗治疗。MRI被认为是LVEF的参考标准，但是可用性可能有限，幽闭恐惧症或金属植入物仍然存在挑战。CT已被证明是准确的，将是有利的，因为LVEF可以与常规的胸-腹-盆腔肿瘤CT一起测量。然而,由于辐射剂量过大，不建议使用CT。本研究旨在探索使用模拟减少剂量的潜力。使用13个剂量水平的拟人化心脏模型扫描，提出了一种噪声仿真算法来引入可控泊松噪声。对滤波后的反投影参数进行迭代测试，以最大程度地减少心肌与心室对比/噪声比的差异，以及在所有剂量水平下真实图像和模拟图像之间的结构相似性指数（SSIM）差异。51例临床CT冠状动脉造影,全剂量扫描通过收缩末期和舒张期，被回顾性地定位。使用开发的算法，引入的噪声对应于原始剂量水平的25％，10％，5％和2％。使用临床软件(Syngo。通过VB50）在LV体积中和排除了乳头状肌。在每个剂量水平，LVEF与100%剂量水平相比，使用Bland-Altman分析。使用0.026mSv/mGycm的转换因子从DLP计算有效剂量。
结果：在临床图像中，平均CTDIvol和DLP为47.1mGy和771.9mGycm，分别(有效剂量20.0mSv)。在25％、10％和5％的模拟剂量下，排除了乳头状肌的测量结果对全剂量图像的LVEF偏差没有统计学意义。在2%的剂量下，发现4.4%的显著偏差.包括乳头状肌肉，在所有模拟剂量水平下都发现了小但显著的偏差。
结论：假设测量是用不包括左心室容积的乳头状肌进行的，剂量可以减少20倍而不显著影响LVEF测量。这对应于1mSv的有效剂量。CT可以潜在地用于具有最小过度辐射的LVEF测量。
结果：在临床图像中，平均CTDIvol和DLP为47.1mGy和771.9mGycm，分别(有效剂量20.0mSv)。在25％、10％和5％的模拟剂量下，排除了乳头状肌的测量结果对全剂量图像的LVEF偏差没有统计学意义。在2%的剂量下，发现4.4%的显著偏差.包括乳头状肌肉，在所有模拟剂量水平下都发现了小但显著的偏差。
结论：假设测量是用不包括左心室容积的乳头状肌进行的，剂量可以减少20倍而不显著影响LVEF测量。这对应于1mSv的有效剂量。CT可以潜在地用于具有最小过度辐射的LVEF测量。
