Ultrashort Echo Time (UTE) Magnetic Resonance Imaging of the Spine

脊柱超短回波时间 (UTE) 磁共振成像

• 批准号: 465643606
• 负责人: Privatdozent Dr. Sam Sedaghat
• 金额: --
• 依托单位: Klinik für Diagnostische und Interventionelle Radiologie
• 依托单位国家: 德国
• 项目类别: WBP Fellowship
• 财政年份: 2021
• 资助国家: 德国
• 起止时间: 2020-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/465643606?language=en
• 关键词: Ultrashort; Echo; Time; UTE; Magnetic

Intervertebral disc (IVD) degeneration and low back pain (LBP) affect the majority of people over their lifetime. LBP is associated with high healthcare costs, disability and loss of productivity. The need for accurate diagnoses as well as focused preventive and therapeutic strategies is therefore a major public health concern. The IVD consists of a central proteoglycan (PG)-rich nucleus pulposus (NP), and a surrounding collagen-rich annulus fibrosus (AF), as well as superiorly and inferiorly located endplates. The IVD relies on diffusion of nutrients and waste through the cartilaginous endplate (CEP) to maintain its health. IVD degeneration is characterized by loss of PGs, dehydration of the NP and collagen loss within the AF, as well as degradation of the CEP. Magnetic resonance imaging (MRI) is routinely used in the diagnosis of IVD degeneration but do not provide reliable assessment of disc biochemical content or CEP function. Recent research has focused on two biomarkers to provide information of this type: T2 for collagen degradation and T1ρ for PG depletion. However, both biomarkers are confounded by the magic angle effect, which may result in a spurious several-fold increase in both T2 and T1ρ. In addition, the CEP is “invisible” on clinical MRI exams due to its short apparent transverse relaxation time (T2*). To address these problems, adiabatic spin-lock imaging has recently been proposed for T1ρ mapping with decreased magic angle sensitivity. Magnetization transfer (MT) has also been introduced for magic angle-insensitive mapping of macromolecular fraction (MMF). Further, ultrashort echo time (UTE) sequences with TEs ~100 times shorter than those of clinical sequences have been implemented to allow direct imaging of the CEP. The UTE research laboratory at the University of California San Diego (UCSD) has developed a series of UTE techniques for quantitative imaging of the disc, including a 3D UTE adiabatic T1ρ (UTE-AdiabT1ρ) sequence for robust mapping of PGs, a 3D UTE MT (UTE-MT) sequence for robust mapping of MMF, and an adiabatic inversion recovery UTE with fat saturation (IR-FS-UTE) sequence for high contrast imaging and T2* mapping of the CEP to evaluate calcification and dehydration. In this study we will a) evaluate the 3D UTE-AdiabT1ρ sequence to map PGs in the NP, and the 3D UTE-MT sequence to map MMF and collagen in the AF. We will also evaluate the impact of the magic angle effect on these sequences in intact IVDs, b) evaluate the 3D IR-FS-UTE sequence to image the CEP and quantify its T2*, and to investigate its calcification and hydration, c) correlate UTE-AdiabT1ρ, MMF and T2* and clinical MRI measures with reference standards including CT, µCT, histology, biochemistry, and diffusion test. We will demonstrate that novel 3D UTE sequences allow volumetric mapping of PG in the NP, collagen in the AF, and diffusivity of the CEP, thereby providing more robust assessment of early IVD degeneration.

腰椎间盘(IVD)退行性变和下腰痛(LBP)影响着大多数人的一生。LBP与高昂的医疗成本、残疾和生产力损失有关。因此，需要准确的诊断以及有重点的预防和治疗战略是一个重大的公共卫生问题。IVD由中央富含蛋白多糖(PG)的髓核(NP)和周围富含胶原的纤维环(AF)以及位于上下两个位置的终板组成。IVD依靠通过软骨终板(CEP)扩散营养物质和废物来维持其健康。IVD变性的特征是PGs丢失，房颤内NP脱水和胶原丢失，以及CEP的降解。磁共振成像(MRI)被常规用于诊断IVD退变，但不能提供对椎间盘生化含量或CEP功能的可靠评估。最近的研究集中在两个提供这类信息的生物标志物上：T2用于胶原降解，T1ρ用于PG耗竭。然而，这两个生物标志物都被魔角效应混淆了，这可能导致T2和T1ρ的虚假数倍增加。此外，CEP在临床MRI检查中是“看不见的”，因为它的表观横向松弛时间很短(T2*)。为了解决这些问题，绝热自旋锁定成像最近被提出用于降低幻角灵敏度的T1ρ映射。磁化转移(MT)也被引入到大分子分数(MMF)的魔角不敏感映射中。此外，还实施了超短回波时间(UTE)序列，其TES比临床序列短100倍，以实现CEP的直接成像。加州大学圣地亚哥分校的UTE研究实验室开发了一系列UTE技术用于椎间盘的定量成像，包括用于PG稳健定位的3D UTE绝热T1ρ(UTE-ADIABT1ρ)序列，用于稳健定位MMF的3D UTE MT(UTE-MT)序列，以及用于高对比度成像的绝热反转恢复UTE(IR-FS-UTE)序列和用于评估钙化和脱水的CEP的T2*成像。在本研究中，我们将a)评估3D UTE-AdiabT1ρ序列用于定位NP中的PG，以及3D UTE-MT序列用于定位房颤中的基质金属纤维和胶原。我们还将评估魔角效应对完整IVD这些序列的影响，b)评估3D IR-FS-UTE序列以成像CEP并量化其T2*，并研究其钙化和水化，c)将UTE-AdiabT1ρ、MMF和T2*与临床磁共振测量相关联，包括CT、µCT、组织学、生化和扩散试验。我们将证明，新的3D UTE序列可以对NP中的PG、AF中的胶原和CEP的扩散性进行体积映射，从而提供更可靠的早期IVD退变评估。