Institut des Sciences Moléculaires, UMR5255, Université de Bordeaux, Talence, France.
Canon Medical Systems Europe, Zoetermeer, Netherlands.
Eur Radiol Exp. 2024 Oct 8;8(1):109. doi: 10.1186/s41747-024-00517-2.
Longitudinal T1 relaxation time is a key imaging biomarker. In addition, T1 values are modulated by the administration of T1 contrast agents used in patients with tumors and metastases. However, in clinical practice, dedicated T1 mapping sequences are often not included in brain MRI protocols. The aim of this study is to address the absence of dedicated T1 mapping sequences in imaging protocol by deriving T1 maps from standard T1-weighted sequences.
A phantom, composed of 144 solutions of paramagnetic agents at different concentrations, was imaged with a three-dimensional (3D) T1-weighed turbo spin-echo (TSE) sequence designed for brain imaging. The relationship between the T1 values and the signal intensities was established using this phantom acquisition. T1 mapping derived from 3D T1-weighted TSE acquisitions in four healthy volunteers and one patient with brain metastases were established and compared to reference T1 mapping technique. The concentration of Gd-based contrast agents in brain metastases were assessed from the derived T1 maps.
Based on the phantom acquisition, the relationship between T1 values and signal intensity (SI) was found equal to T1 = 0.35 × SI (R = 0.97). TSE-derived T1 values measured in white matter and gray matter in healthy volunteers were equal to 0.997 ± 0.096 s and 1.358 ± 0.056 s (mean ± standard deviation), respectively. Mean Gd concentration value in brain metastases was 94.7 ± 30.0 μM.
The in vivo results support the relevance of the phantom-based approach: brain T1 maps can be derived from T1-weighted acquisitions.
High-resolution brain T1 maps can be generated, and contrast agent concentration can be quantified and imaged in brain metastases using routine 3D T1-weighted TSE acquisitions.
Quantitative T1 mapping adds significant value to MRI diagnostics. T1 measurement sequences are rarely included in routine protocols. T1 mapping and concentration of contrast agents can be derived from routine standard scans. The diagnostic value of MRI can be improved without additional scan time.
纵向 T1 弛豫时间是关键的成像生物标志物。此外，T1 值受肿瘤和转移患者中使用的 T1 对比剂给药的调节。然而，在临床实践中，专门的 T1 映射序列通常不包含在脑 MRI 方案中。本研究的目的是通过从标准 T1 加权序列中推导出 T1 图来解决成像方案中缺乏专门 T1 映射序列的问题。
使用专为脑成像设计的三维（3D）T1 加权涡轮自旋回波（TSE）序列对由不同浓度顺磁剂组成的 144 个溶液的体模进行成像。使用该体模采集建立 T1 值与信号强度之间的关系。在四名健康志愿者和一名脑转移患者中建立并比较了来自 3D T1 加权 TSE 采集的 T1 映射，以及参考 T1 映射技术。从推导出的 T1 图中评估脑转移瘤中基于 Gd 的对比剂的浓度。
基于体模采集，发现 T1 值与信号强度（SI）之间的关系等于 T1=0.35×SI（R=0.97）。在健康志愿者的白质和灰质中测量的 TSE 衍生 T1 值分别等于 0.997±0.096 s 和 1.358±0.056 s（平均值±标准差）。脑转移瘤中的平均 Gd 浓度值为 94.7±30.0 μM。
体内结果支持基于体模的方法的相关性：可以从 T1 加权采集推导出脑 T1 图。
可以生成高分辨率脑 T1 图，并使用常规 3D T1 加权 TSE 采集对脑转移瘤中的对比剂浓度进行定量和成像。
定量 T1 映射为 MRI 诊断增加了重要价值。T1 测量序列很少包含在常规方案中。可以从常规标准扫描中推导出 T1 映射和对比剂浓度。无需额外的扫描时间即可提高 MRI 的诊断价值。
