This study aimed to develop a rapid, 1 mm3isotropic resolution, whole-brain MRI technique for automatic lesion segmentation and multi-parametric mapping without using contrast by continuously applying balanced steady-state free precession with inversion pulses throughout incomplete inversion recovery in a single 6 min scan. Modified k-means clustering was performed for automatic brain tissue and lesion segmentation using distinct signal evolutions that contained mixed T1/T2/magnetization transfer properties. Multi-compartment modeling was used to derive quantitative multi-parametric maps for tissue characterization. Fourteen patients with contrast-enhancing gliomas were scanned with this sequence prior to the injection of a contrast agent, and their segmented lesions were compared to conventionally defined manual segmentations of T2-hyperintense and contrast-enhancing lesions. Simultaneous T1, T2, and macromolecular proton fraction maps were generated and compared to conventional 2D T1 and T2 mapping and myelination water fraction mapping acquired with MAGiC. The lesion volumes defined with the new method were comparable to the manual segmentations (r = 0.70,p< 0.01;t-testp> 0.05). The T1, T2, and macromolecular proton fraction mapping values of the whole brain were comparable to the reference values and could distinguish different brain tissues and lesion types (p< 0.05), including infiltrating tumor regions within the T2-lesion. Highly efficient, whole-brain, multi-contrast imaging facilitated automatic lesion segmentation and quantitative multi-parametric mapping without contrast, highlighting its potential value in the clinic when gadolinium is contraindicated.
本研究旨在开发一种快速、各向同性分辨率为1 mm³的全脑磁共振成像技术，在不使用造影剂的情况下实现自动病灶分割和多参数成像。该技术通过在单次6分钟扫描中，于不完全反转恢复期间持续应用带反转脉冲的平衡稳态自由进动序列来实现。利用包含混合T1/T2/磁化转移特性的独特信号演化特征，采用改进的k均值聚类算法进行自动脑组织及病灶分割。通过多室模型推导定量多参数图谱以进行组织表征。在注射造影剂前，使用该序列对14例对比增强型胶质瘤患者进行扫描，并将其分割病灶与传统定义的T2高信号及对比增强病灶手动分割结果进行比较。同时生成的T1、T2及大分子质子分数图谱，与采用MAGiC序列获取的传统二维T1/T2成像及髓鞘水分数成像结果进行对比。新方法定义的病灶体积与手动分割结果具有可比性（r=0.70，p<0.01；t检验p>0.05）。全脑T1、T2及大分子质子分数成像值与参考值相当，并能区分不同脑组织及病灶类型（p<0.05），包括T2病灶内的浸润性肿瘤区域。这种高效的全脑多对比度成像技术实现了无造影剂的自动病灶分割和定量多参数成像，凸显了其在钆造影剂禁忌情况下的临床潜在价值。
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