Advanced MRI Evaluation of Abdominal Aortic Aneurysms

腹主动脉瘤的高级 MRI 评估

• 批准号: 10316268
• 负责人: Dimitrios Mitsouras
• 金额: --
• 依托单位: VETERANS AFFAIRS MED CTR SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-10-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10316268
• 关键词: 3-Dimensional; Abdominal Aortic Aneurysm; Affect; Aging; Anatomy; Aneurysm; Aorta; Aortic Diseases; Biomechanics; Blood Vessels; Blood flow; Central Artery; Cessation of life; Clinical; Computer Models; Data; Descriptor; Diameter; Dimensions; Disease; Disease Progression; Early Intervention; Evaluation; Functional Imaging; Future; Goals; Growth; Hematological Disease; Image; Imaging Techniques; Inflammation; Inflammatory; Intervention; Life; Magnetic Resonance Imaging; Measurement; Mechanics; Morphology; Motivation; Operative Surgical Procedures; Outcome; Pathologic; Patients; Pattern; Persons; Phase; Process; Protocols documentation; Regimen; Reporting; Resolution; Resources; Risk; Risk Assessment; Role; Rupture; Ruptured Abdominal Aortic Aneurysm; Series; Stress; Stretching; Structure; Time; Vascular Diseases; Veterans; anatomic imaging; biomechanical model; biomechanical test; contrast enhanced; data modeling; experience; hemodynamics; improved; improved outcome; innovation; male; military veteran; older men; patient stratification; rapid growth; risk stratification; screening; screening program; shear stress; surveillance imaging; ultrasound

Abdominal aortic aneurysms (AAA) are common and can be life-threatening if they progress to rupture. They have been reported in up to 8% of older men and account for over 15,000 deaths per year. Basic vessel dimensions are currently the primary imaging measurement used clinically to risk-stratify patients. But there is more to the story than dimensions. Wall stress estimated with computational biomechanical modeling may better predict growth and rupture than diameters. Furthermore, AAA growth is often not continuous, and instead marked by periods of rapid growth followed by quiescence. Small series report that unrelated surgical procedures can precipitate AAA rupture, suggesting that episodic and heterogeneous inflammatory processes in concert with adverse hemodynamics and biomechanics are important for the progression of AAA disease. The complexity of aortic disease is more fully revealed with new functional imaging techniques than with conventional anatomic analysis alone. While AAA has been extensively studied, the mechanisms of disease progression have not been fully elucidated. If better understood, they could lead to significant improvement of the management of veterans with small AAAs (< 5.5 cm). Many of these aneurysms can be followed safely with a long screening interval of 2-3 years, but some may progress to rupture. Identifying this subset would greatly streamline the surveillance imaging of veterans with AAA. On the other hand, the majority of AAAs never rupture, and identifying low risk veterans could help better manage resources and subject only those veterans at truly elevated risk to intervention. MRI uniquely offers comprehensive assessment of forces acting on the vessel wall (hemodynamics and biomechanics), as well as factors affecting wall strength (structure, morphology and inflammation). Blood flow imaging with time-resolved 3D phase-contrast MRI (4D Flow) allows quantification of key parameters including flow turbulence and wall shear stress. Dynamic contrast enhanced (DCE) MRI may offer efficient evaluation of aortic wall inflammation. Cine Displacement Encoding with Stimulated Echoes (DENSE) MRI can quantify regional stretch differences experienced by the vessel wall, and, in tandem with 3D volumetric MRI anatomic data and computational modeling can be used to calculate patient-specific mechanical wall stress. The aim of our study is to uncover important inflammatory changes and adverse hemodynamics and biomechanics that are not addressed by current imaging, and use them to predict AAA disease progression. We also seek to optimize a short (5 minute) MRI protocol without contrast to determine if there is added value to this comprehensive assessment, as fast non-contrast MRI would be preferable and more efficiently use VA resources. Our overall goal is to meaningfully advance the assessment of risk in veterans who do not meet current intervention thresholds and thereby in the future improve outcomes by refining surveillance imaging regimens and decisions regarding early intervention for AAAs.

腹主动脉瘤（AAA）很常见，如果进展到破裂可能会危及生命。他们 据报道，高达 8% 的老年男性患有此病，每年导致 15,000 多人死亡。基本容器 目前，尺寸是临床上用于对患者进行风险分层的主要成像测量。但有 故事的意义大于尺寸。通过计算生物力学模型估计的壁应力可以 比直径更好地预测生长和破裂。此外，AAA 的增长通常不是连续的，并且 相反，其特点是快速增长时期和随后的停滞时期。小编报道无关手术 手术可促使 AAA 破裂，表明间歇性和异质性炎症过程 与不良血流动力学和生物力学相结合对于 AAA 疾病的进展很重要。 新的功能成像技术比传统的成像技术更能全面地揭示主动脉疾病的复杂性。 仅进行常规解剖分析。虽然 AAA 已被广泛研究，但疾病的机制 进展尚未完全阐明。如果更好地理解它们，它们可能会带来显着的改善 管理患有小 AAA（< 5.5 厘米）的退伍军人。许多动脉瘤都可以安全地进行随访 筛查间隔较长，可达2-3年，但有些可能会进展至破裂。识别这个子集将 通过 AAA 极大地简化了退伍军人的监视成像。另一方面，大多数 AAA 永远不会破裂，识别低风险退伍军人可以帮助更好地管理资源并仅对那些 退伍军人面临的干预风险确实很高。 MRI 独特地提供了对作用在血管壁上的力（血流动力学和 生物力学），以及影响壁强度的因素（结构、形态和炎症）。血流（量 使用时间分辨 3D 相衬 MRI（4D Flow）成像可以量化关键参数，包括 流动湍流和壁面剪切应力。动态对比增强 (DCE) MRI 可有效评估 主动脉壁炎症。受激回声 (DENSE) MRI 的电影位移编码可以量化 血管壁所经历的区域拉伸差异，并与 3D 体积 MRI 解剖相结合 数据和计算模型可用于计算患者特定的机械壁应力。 我们研究的目的是揭示重要的炎症变化和不良血流动力学以及 现有影像学无法解决的生物力学问题，并用它们来预测 AAA 疾病进展。 我们还寻求优化无对比的短（5 分钟）MRI 方案，以确定是否有附加值 对于这种综合评估，因为快速非对比 MRI 更可取并且更有效地使用 VA 资源。我们的总体目标是有意义地推进对不符合条件的退伍军人的风险评估 当前的干预阈值，从而在未来通过改进监测成像来改善结果 有关 AAA 早期干预的方案和决策。