Zhu Zhengyang, Xue Xunwen, Tang Tang, Luo Chao, Li Ye, Chen Jing, Xu Biyun, Lin Zengping, Zhang Xin, Wang Zhengge, Chen Jun, Lu Jiaming, Zhang Wen, Li Xin, Chen Qian, Jiang Zhuoru, Wang Junxia, Hu Qing, Haller Sven, Li Ming, Yan Chenchen, Zhang Bing
Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China.
Medical Imaging Center, Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, Jiangsu, China.
J Magn Reson Imaging. 2025 Jun;61(6):2505-2515. doi: 10.1002/jmri.29677. Epub 2025 Jan 21.
At high magnetic fields, degraded image quality due to dielectric artifacts and elevated specific absorption rate (SAR) are two technical challenges in fetal MRI.
To assess the potential of high dielectric constant (HDC) pad in increasing image quality and decreasing SAR for 3 T fetal MRI.
Prospective.
FIELD STRENGTH/SEQUENCE: 3 T. Balanced steady-state free precession (bSSFP) and single-shot fast spin-echo (SSFSE).
One hundred twenty-eight participants (maternal-age 29.0 ± 3.6, range 20-40; gestational-age 30.3 ± 3.5 weeks, range 22-37 weeks) undertook bSSFP and 40 participants (maternal-age 29.5 ± 3.8, range 19-40; gestational-age 30.4 ± 3.5 weeks, range 23-37 weeks) undertook SSFSE.
Patient clinical characteristics were recorded, such as gestational-age, amniotic-fluid-index, abdominal-circumference, body-mass-index, and fetal-presentation. Quantitative Image-quality analysis included signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Qualitative analysis was performed by three radiologists with four-point scale to evaluate overall image quality, dielectric artifact, and diagnostic confidence. Whole-body total SAR was obtained from the vendor workstation.
Paired rank sum test was used to analyze the differences in SNR, CNR, overall image quality, dielectric artifact, diagnostic confidence, and SAR with and without HDC pad. Spearman correlation test was used to detect correlations between image quality variable changes and patient clinical characteristics. P values <0.05 were set as statistical significance.
With HDC pad, SNR and CNR was significantly higher (41.45% increase in SNR, 54.05% increase in CNR on bSSFP; 258.76% increase in SNR, 459.55% increase in CNR on SSFSE). Overall qualitative image quality, dielectric artifact and diagnostic confidence improved significantly. Adding HDC pad significantly reduced Whole-body total SAR (32.60% on bSSFP; 15.40% on SSFSE). There was no significant correlation between image quality variable changes and participant clinical characteristics (P-values ranging from 0.072 to 0.992).
In the clinical setting, adding a HDC pad might increase image quality while reducing dielectric artifact and SAR.
Dielectric artifacts and elevated SAR are two technical problems in 3T fetal MRI. In a prospective analysis of 168 pregnant participants undertaking 3.0T fetal MRI scanning, high dielectric constant (HDC) pad increased SNR by 41.45%, CNR by 54.05% on bSSFP, and SNR by 258.76%, CNR by 459.55% on SSFSE. Overall image quality, dielectric artifact reduction, and diagnostic confidence assessed by three radiologists was improved. Whole-body total SAR decreased by 32.60% on bSSFP and by 15.40% on SSFSE. These findings suggested that the HDC pad can enhance fetal MRI safety and quality, making it a promising tool for clinical practice.
2 TECHNICAL EFFICACY: Stage 5.
在高磁场下，由于介电伪影导致的图像质量下降和比吸收率（SAR）升高是胎儿磁共振成像（MRI）中的两个技术挑战。
评估高介电常数（HDC）垫在提高3T胎儿MRI图像质量和降低SAR方面的潜力。
前瞻性研究。
场强/序列：3T。平衡稳态自由进动（bSSFP）和单次激发快速自旋回波（SSFSE）。
128名参与者（母亲年龄29.0±3.6岁，范围20 - 40岁；孕周30.3±3.5周，范围22 - 37周）接受bSSFP检查，40名参与者（母亲年龄29.5±3.8岁，范围19 - 40岁；孕周30.4±3.5周，范围23 - 37周）接受SSFSE检查。
记录患者的临床特征，如孕周、羊水指数、腹围、体重指数和胎儿胎位。定量图像质量分析包括信噪比（SNR）和对比噪声比（CNR）。由三名放射科医生采用四分制进行定性分析，以评估整体图像质量、介电伪影和诊断置信度。从供应商工作站获取全身总SAR。
采用配对秩和检验分析使用和不使用HDC垫时SNR、CNR、整体图像质量、介电伪影、诊断置信度和SAR的差异。采用Spearman相关性检验检测图像质量变量变化与患者临床特征之间的相关性。P值<0.05被设定为具有统计学意义。
使用HDC垫时，SNR和CNR显著更高（bSSFP上SNR增加41.45%，CNR增加54.05%；SSFSE上SNR增加258.76%，CNR增加459.55%）。整体定性图像质量、介电伪影和诊断置信度显著改善。添加HDC垫显著降低了全身总SAR（bSSFP上降低32.60%；SSFSE上降低15.40%）。图像质量变量变化与参与者临床特征之间无显著相关性（P值范围为0.072至0.992）。
在临床环境中，添加HDC垫可能会提高图像质量，同时减少介电伪影和SAR。
介电伪影和SAR升高是3T胎儿MRI中的两个技术问题。在对168名进行3.0T胎儿MRI扫描的孕妇进行的前瞻性分析中，高介电常数（HDC）垫在bSSFP上使SNR提高41.45%，CNR提高54.05%，在SSFSE上使SNR提高258.76%，CNR提高459.55%。由三名放射科医生评估的整体图像质量、介电伪影减少和诊断置信度得到改善。bSSFP上全身总SAR降低32.60%，SSFSE上降低15.40%。这些发现表明，HDC垫可以提高胎儿MRI的安全性和质量，使其成为临床实践中有前景的工具。
2 技术效能：5级
