Abstract：
Normalized signal intensity (SI) obtained from magnetic resonance imaging (MRI) has been used to track anterior cruciate ligament (ACL) postoperative remodeling. We aimed to assess the effect of MRI sequence (PD: proton density-weighted; T2: T2-weighted; CISS: constructive interference in steady state) on postoperative changes in healing ACLs/grafts. We hypothesized that CISS is better at detecting longitudinal SI and texture changes of the healing ACL/graft compared to the common clinical sequences (PD and T2). MR images of patients who underwent ACL surgery were evaluated and separated into groups based on surgical procedure (Bridge-Enhanced ACL Repair (BEAR; n = 50) versus ACL reconstruction (ACLR; n = 24)). CISS images showed decreasing SI across all timepoints in both the BEAR and ACLR groups (p < 0.01), PD and T2 images showed decreasing SI in the 6-to-12- and 12-to-24-month postoperative timeframes in the BEAR group (p < 0.02), and PD images additionally showed decreasing SI between 6- and 24-months postoperation in the ACLR group (p = 0.02). CISS images showed texture changes in both the BEAR and ACLR groups, showing increases in energy and decreases in entropy in the 6-to-12- and 6-to-24-month postoperative timeframes in the BEAR group (p < $\\lt $ 0.04), and increases in energy, decreases in entropy, and increases in homogeneity between 6 and 24 months postoperation in the ACLR group (p < 0.04). PD images showed increases in energy and decreases in entropy between 6- and 24-months postoperation in the ACLR group (p < 0.008). Finally, CISS was estimated to require a smaller sample size than PD and T2 to detect SI differences related to postoperative remodeling.
摘要：
从磁共振成像（MRI）获得的归一化信号强度（SI）已用于跟踪前交叉韧带（ACL）术后重塑。我们旨在评估MRI序列（PD：质子密度加权；T2：T2加权；CISS：稳态下的建设性干扰）对术后愈合ACL/移植物变化的影响。我们假设与常见临床序列（PD和T2）相比，CISS在检测愈合ACL/移植物的纵向SI和质地变化方面更好。评估接受ACL手术的患者的MR图像，并根据手术程序（桥接增强ACL修复（BEAR；n=50）与ACL重建（ACLR；n=24））分组。CISS图像显示BEAR和ACLR组的所有时间点SI均降低（p<0.01），PD和T2图像显示，在BEAR组术后6至12个月和12至24个月的时间范围内SI降低（p<0.02），和PD图像还显示ACLR组术后6至24个月SI降低(p=0.02).CISS图像显示BEAR和ACLR组的纹理变化，在BEAR组中，在术后6至12和6至24个月的时间范围内显示能量增加和熵减少（p<$\\lt$0.04），能量的增加，熵减少，ACLR组术后6至24个月的同质性增加（p<0.04）。PD图像显示ACLR组术后6至24个月能量增加，熵降低（p<0.008）。最后,估计CISS需要比PD和T2更小的样本量来检测与术后重塑相关的SI差异。
