Wu Zhengxiu, Guo Jiangqian, Tang Zicheng, Hu Xiaokai, Jiang Xiaowen, Ni Zhonghua, Lu Rongsheng
Jiangsu Key Laboratory for Design and Manufacturing of Precision Medicine Equipment, Southeast University, Nanjing, China.
School of Mechanical Engineering, Southeast University, Nanjing, China.
NMR Biomed. 2025 Aug;38(8):e70081. doi: 10.1002/nbm.70081.
The renewed interest in ultra-low-field MRI (< 0.1 T), with its advantages of cost-effectiveness and portability, is expected to drive a paradigm shift from traditional MRI scanners to point-of-care imaging systems. Here, we characterized the in vivo T and T relaxation times of healthy breast tissues using quantitative MRI at 50 mT to advance the development of ultra-low-field breast MRI methodologies. First, the developed in vivo quantitative mapping protocols were tested and validated using CuSO-doped water phantom experiments on the custom-built 50-mT MRI prototype. Then, in vivo quantitative T and T mapping of human breast tissues was measured in healthy female subjects. The T and T values for fat tissue, fibrous tissue, and glandular tissue components were determined using an automatic segmentation method based on the relaxation times. The mean T times were 121.21 ± 14.57, 182.26 ± 20.96, and 238.32 ± 10.71 ms for fat tissue, fibrous tissue, and glandular tissue, respectively. While the mean T times were 111.36 ± 14.28 and 69.44 ± 15.26 ms for fat tissue and fibroglandular tissue, respectively. For healthy breast tissues, the significantly shorter T times at 50 mT are favorable for improving the imaging speed. T times are similar to those seen at conventional clinical field strengths. Additionally, the relatively small difference in T times between fibrous tissue and glandular tissue made it difficult to segment these two tissues independently. This work can provide a valuable reference for future breast tissues diagnostic imaging in ultra-low-field MRI scenarios, thereby promoting the wider adoption of portable breast MRI in routine breast disease screening.
对超低场磁共振成像（<0.1 T）重新燃起的兴趣，因其具有成本效益和便携性的优势，有望推动从传统磁共振成像扫描仪向床旁成像系统的范式转变。在此，我们使用50 mT的定量磁共振成像对健康乳腺组织的体内T1和T2弛豫时间进行了表征，以推进超低场乳腺磁共振成像方法的发展。首先，在定制的50 mT磁共振成像原型上，通过硫酸铜掺杂水模体实验对所开发的体内定量映射协议进行了测试和验证。然后，在健康女性受试者中测量了人体乳腺组织的体内定量T1和T2映射。使用基于弛豫时间的自动分割方法确定了脂肪组织、纤维组织和腺组织成分的T1和T2值。脂肪组织、纤维组织和腺组织的平均T1时间分别为121.21±14.57、182.26±20.96和238.32±10.71 ms。而脂肪组织和纤维腺组织的平均T2时间分别为111.36±14.28和69.44±15.26 ms。对于健康乳腺组织，50 mT时明显更短的T2时间有利于提高成像速度。T1时间与传统临床场强下的相似。此外，纤维组织和腺组织之间T2时间的相对较小差异使得难以独立分割这两种组织。这项工作可为未来超低场磁共振成像场景下的乳腺组织诊断成像提供有价值的参考，从而促进便携式乳腺磁共振成像在常规乳腺疾病筛查中的更广泛应用。
