Rimkus Carolina de Medeiros, Otsuka Fábio Seiji, Nunes Douglas Mendes, Chaim Khallil Taverna, Otaduy Maria Concepción Garcia
Department of Radiology and Oncology, Hospital das Clínicas da Faculdade de Medicina da Universidade de Sao Paulo (HCFMUSP), Sao Paulo 05403-010, SP, Brazil.
Laboratory of Medical Investigation in Magnetic Resonance-44 (LIM 44), University of Sao Paulo, Sao Paulo 05403-000, SP, Brazil.
Diagnostics (Basel). 2024 Jun 27;14(13):1362. doi: 10.3390/diagnostics14131362.
Multiple sclerosis (MS) is the most common acquired inflammatory and demyelinating disease in adults. The conventional diagnostic of MS and the follow-up of inflammatory activity is based on the detection of hyperintense foci in T2 and fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) and lesions with brain-blood barrier (BBB) disruption in the central nervous system (CNS) parenchyma. However, T2/FLAIR hyperintense lesions are not specific to MS and the MS pathology and inflammatory processes go far beyond focal lesions and can be independent of BBB disruption. MRI techniques based on the magnetic susceptibility properties of the tissue, such as T2*, susceptibility-weighted images (SWI), and quantitative susceptibility mapping (QSM) offer tools for advanced MS diagnostic, follow-up, and the assessment of more detailed features of MS dynamic pathology. Susceptibility-weighted techniques are sensitive to the paramagnetic components of biological tissues, such as deoxyhemoglobin. This capability enables the visualization of brain parenchymal veins. Consequently, it presents an opportunity to identify veins within the core of multiple sclerosis (MS) lesions, thereby affirming their venocentric characteristics. This advancement significantly enhances the accuracy of the differential diagnostic process. Another important paramagnetic component in biological tissues is iron. In MS, the dynamic trafficking of iron between different cells, such as oligodendrocytes, astrocytes, and microglia, enables the study of different stages of demyelination and remyelination. Furthermore, the accumulation of iron in activated microglia serves as an indicator of latent inflammatory activity in chronic MS lesions, termed paramagnetic rim lesions (PRLs). PRLs have been correlated with disease progression and degenerative processes, underscoring their significance in MS pathology. This review will elucidate the underlying physical principles of magnetic susceptibility and their implications for the formation and interpretation of T2*, SWI, and QSM sequences. Additionally, it will explore their applications in multiple sclerosis (MS), particularly in detecting the central vein sign (CVS) and PRLs, and assessing iron metabolism. Furthermore, the review will discuss their role in advancing early and precise MS diagnosis and prognostic evaluation, as well as their utility in studying chronic active inflammation and degenerative processes.
多发性硬化症（MS）是成人中最常见的获得性炎症性脱髓鞘疾病。MS的传统诊断及炎症活动的随访基于T2加权成像和液体衰减反转恢复（FLAIR）磁共振成像（MRI）中高信号灶的检测，以及中枢神经系统（CNS）实质内具有血脑屏障（BBB）破坏的病变。然而，T2/FLAIR高信号病变并非MS所特有，且MS病理和炎症过程远不止局灶性病变，并且可能与BBB破坏无关。基于组织磁敏感性特性的MRI技术，如T2*、磁敏感加权成像（SWI）和定量磁敏感成像（QSM），为MS的高级诊断、随访以及MS动态病理更详细特征的评估提供了工具。磁敏感加权技术对生物组织的顺磁性成分，如脱氧血红蛋白敏感。这种能力使得脑实质静脉得以可视化。因此，它提供了一个机会来识别多发性硬化症（MS）病变核心内的静脉，从而证实其以静脉为中心的特征。这一进展显著提高了鉴别诊断过程的准确性。生物组织中的另一个重要顺磁性成分是铁。在MS中，铁在不同细胞（如少突胶质细胞、星形胶质细胞和小胶质细胞）之间的动态转运有助于研究脱髓鞘和再髓鞘化的不同阶段。此外，活化小胶质细胞中铁的积累是慢性MS病变中潜在炎症活动的指标，称为顺磁性边缘病变（PRL）。PRL与疾病进展和退行性过程相关，突出了它们在MS病理中的重要性。本综述将阐明磁敏感性的基本物理原理及其对T2*、SWI和QSM序列形成和解释的影响。此外，还将探讨它们在多发性硬化症（MS）中的应用，特别是在检测中央静脉征（CVS）和PRL以及评估铁代谢方面。此外，本综述将讨论它们在推进早期和精确的MS诊断及预后评估中的作用，以及它们在研究慢性活动性炎症和退行性过程中的效用。
