Klint Elisabeth, Tisell Anders, Blystad Ida, Hallbeck Martin, Nordin Teresa, Hillman Jan, Richter Johan, Wårdell Karin
Department of Biomedical Engineering, Linköping University, Sweden.
Department of Radiation Physics in Linköping, and Department of Health, Medicine and Caring Sciences, Linköping University, Sweden.
PLoS One. 2025 Jul 7;20(7):e0326765. doi: 10.1371/journal.pone.0326765. eCollection 2025.
Quantitative MRI (qMRI) relaxometry holds potential for brain tumor identification beyond contrast enhancement on conventional images. However, clinical implementation is limited by long acquisition times, changing conditions between imaging and surgery, and lack of correlation with standard techniques.
To extend a methodology for multimodal data analysis to relaxometry data. To integrate relaxometry into the burr hole needle biopsy procedure with optical guidance, setup a workflow for multimodal data processing and analysis, and apply the methodology in a clinical setting.
Multi-dimensional multi-echo relaxometry data (2x6 min) was acquired in addition to the clinical imaging protocol. Relaxation rate and proton density maps, as well as their differences were calculated before (R1, R2) and after gadolinium contrast-agent administration (R1Gd, R2Gd). Radiological volumes of interest (VOIs: tumor, edema, white matter, and biopsy) were defined on clinical images. Rate distribution changes were analyzed on three levels: the biopsied volume, along the needle trajectory (4x4x4 mm3 volumes), and VOIs. Increased R1Gd and R2Gd were compared to indications from 5-aminolevulinic acid-induced fluorescence and detailed neuropathological evaluation.
Neuropathological analysis confirmed seven glioblastoma, one lymphoma, and one non-tumorous diagnosis. Increased R1Gd was found in all biopsied volumes, although tumorous volumes presented larger R1Gd increase (3-9 times) compared to volumes dominated by necrotic or non-tumorous tissue. Along the trajectory, increased R1Gd and R2Gd were not tumor-specific, however, the greatest R1Gd shifts were found in or adjacent to radiologically defined tumorous tissue. Increased relaxation rates corresponded to 82% and 45% (R1Gd: φ = 0.35, R2Gd: φ = 0.27) of fluorescence peaks. In the radiological VOIs, increased R1Gd and R2Gd were found in tumorous tissue, a slight right shift in edematous tissue, and negligible changes in white matter.
Combined analysis suggests increased R1Gd together with fluorescence peaks as a marker for tumor tissue. The presented multimodal approach provides a workflow toward clinical translation of relaxometry.
定量磁共振成像（qMRI）弛豫测量法在识别脑肿瘤方面具有潜力，超越了传统图像上的对比增强。然而，临床应用受到采集时间长、成像与手术之间条件变化以及与标准技术缺乏相关性的限制。
将多模态数据分析方法扩展到弛豫测量数据。将弛豫测量法整合到光学引导下的钻孔针活检程序中，建立多模态数据处理和分析的工作流程，并在临床环境中应用该方法。
除临床成像方案外，还采集了多维多回波弛豫测量数据（2×6分钟）。计算钆对比剂给药前（R1、R2）和给药后（R1Gd、R2Gd）的弛豫率和质子密度图及其差异。在临床图像上定义感兴趣的放射学体积（VOI：肿瘤、水肿、白质和活检）。在三个层面分析速率分布变化：活检体积、沿针轨迹（4×4×4立方毫米体积）和VOI。将增加的R1Gd和R2Gd与5-氨基乙酰丙酸诱导荧光和详细神经病理学评估的指征进行比较。
神经病理学分析证实了7例胶质母细胞瘤、1例淋巴瘤和1例非肿瘤性诊断。在所有活检体积中均发现R1Gd增加，尽管与以坏死或非肿瘤组织为主的体积相比，肿瘤体积的R1Gd增加更大（3至9倍）。沿轨迹，R1Gd和R2Gd增加并非肿瘤特异性，但在放射学定义的肿瘤组织内或附近发现最大的R1Gd变化。增加弛豫率分别对应荧光峰值的82%和45%（R1Gd：φ = 0.35，R2Gd：φ = 0.27）。在放射学VOI中，肿瘤组织中发现R1Gd和R2Gd增加，水肿组织有轻微右移，白质变化可忽略不计。
联合分析表明，增加的R1Gd与荧光峰值一起可作为肿瘤组织标志物。所提出的多模态方法为弛豫测量法的临床转化提供了工作流程。
