Comprehensive quantitative ultrafast 3D liver MRI

描述（由申请人提供）：2006年进行的3020万次MR检查中，约7%为腹部MRI，肝脏是迄今为止使用MR成像的最常见腹部器官[1]。当成功时，MR的病变表征是精致和优雅的，并且信息的确定性可以帮助治疗随访，停止不必要的检查并防止侵入性活检。然而，由于患者屏气困难、关键（和不可重复）定时造影后系列图像中的定时或采集问题、操作员依赖性、图像伪影或不同放射科医师之间因固有定性解释而产生的解释确定性水平差异，肝脏MR通常不成功。加权图像最多是潜在参数的替代品，通常不能很好地反映参数[2]。此外，当定量信息可用时，它甚至可以胜过临床对比的专家读者[3]。如果肝脏检查可以在自由呼吸期间快速进行，而不依赖于操作员的专业知识，并且可以提供可用于明确诊断疾病的定量参数，则对肝脏疾病的诊断和治疗的影响将是显著的。我们建议利用我们团队的快速成像、参数定量和身体MRI专业知识，在10分钟内提供快速、定量、高质量的3D检查。标准肝脏MR检查包括多次扫描，突出显示不同的对比机制：T2加权扫描（无脂肪饱和和有脂肪饱和）、T1加权同相和反相梯度回波、弥散图像和T1加权脂肪饱和3D梯度回波扫描（对比前和对比后至少3个定时相位）。我们将开发、优化和验证方法，通过开发定量3D高分辨率DCE灌注、脂肪分数、T1和T2标测以及改进的3D扩散标测来生成每种机制的定量测量结果。新方案的诊断价值将在活检证实病理的患者中进行广泛测试，并与目前的临床标准进行比较。

DESCRIPTION (provided by applicant): Approximately 7% of the 30.2 million MR exams performed in 2006 were abdominal MRIs, and the liver is by far the most common abdominal organ imaged using MR [1]. When successful, lesion characterization by MR is exquisite and elegant, and the definitive nature of the information can aid treatment follow-up, stop unnecessary workups and prevent invasive biopsies. All too often, however, liver MR is unsuccessful because of patient difficulties with breath-holds, problems with timing or acquisition in the critical (and non-repeatable) timed post-contrast series of images, operator dependence, image artifacts, or differences in levels of certainty in interpretation between various radiologists arising from inherently qualitative interpretations. Weighted images are at best surrogates of the underlying parameter and often poorly reflect the parameters [2]. Moreover, when quantitative information is available, it can outperform even expert readers of clinical contrasts [3]. If the liver examination could be performed quickly during free-breathing, without relying on operator expertise, and could provide quantitative parameters which can be used to definitively diagnose disease, the impact on the diagnosis and treatment of liver diseases would be significant. We propose to leverage rapid imaging, parameter quantitation, and body MRI expertise in our group to provide a rapid, quantitative, high quality 3D exam in under 10 minutes. A standard liver MR exam consists of multiple scans highlighting different contrast mechanisms: T2 weighted scans without and with fat saturation, T1-weighted in- and opposed-phase gradient echo, diffusion images, and T1-weighted fat saturated 3D gradient echo scans pre- and at least 3 timed phases post-contrast). We will develop, optimize and validate methods to generate quantitative measurements of each mechanism, by developing quantitative 3D high resolution DCE perfusion, fat fraction, T1 and T2 mapping, and improved 3D diffusion mapping. The diagnostic value of the new protocol will then be extensively tested on patients with biopsy proven pathologies, and will be compared to the present clinical standard.