Knee evaluation under mechanical loading by cones ultrashort echo time MR imaging

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ABSTRACT: Dr. Jerban is postdoctoral researcher with a multidisciplinary background who is proposing a research entitled “Knee evaluation under mechanical loading by Cones Ultrashort Echo Time MR imaging” through NIH K01 program under the mentorship of Drs. Christine Chung, Samuel Ward, and Jiang Du to develop into an independent investigator. Improving the osteoarthritis (OA) diagnosis at early stage using Magnetic Resonance Imaging (MRI) techniques are limited by three main barriers. First, the current clinical MRI techniques do not acquire signal from short T2 tissues, such as the meniscus and the deep layer of cartilage. Second, most Ultrashort Echo Time (UTE) MRI techniques that can acquire signal from short T2 tissues are orientation sensitive. Third, knee MRI is routinely performed on joints at rest, which incompletely mimics the actual physiological condition, particularly, the loading aspects. Recently, we have developed new UTE-MRI techniques (UTE-Ad-T1ρ and UTE-MT) that are not orientation-sensitive and that are designed specifically for scanning short T2 tissues of the knee. We have hypothesized that scanning knee joints during mechanical load application using these orientation-insensitive techniques will reveal the mechanical properties of the joint tissues, which in turn will help to distinguish between healthy, early stage and mild OA knee joints. We also hypothesized bone remodels in order to enhance the support to cartilage/menisci regions with defected cartilage, which complementarily confirms the early stage OA diagnosis. A research study is proposed to cover three main specific aims: dissected specimens’ study, whole knee cadaveric study, and in vivo study. First, we will accelerate the UTE-MRI techniques and then will investigate their variation patterns in healthy and moderate OA human cartilage/menisci specimens during the loading/unloading process. We will also assess the supporting bone specimens to compare with UTE variation patterns in cartilages/menisci under loading. Second, we will build and verify a pneumatic loading setup for the cadaver whole knee study, which is meant to assess the temporal variation of knees under a set of loading and unloading steps. Then the UTE-MRI variation patterns in joints from healthy, mild OA, and moderate OA groups during the loading/unloading process will be investigated. Third, we will design and build a separate loading device to perform the in vivo phase of the study. We will determine if in vivo UTE-MRI variation pattern under loading are distinct for early stage OA patients, and if UTE-MRI/CT can detect an improved bone structure and properties for early stage and mild OA knees. The feasibility of accelerating our orientation-insensitive UTE-MRI techniques and the significant sensitivity of our techniques to changes in knee tissues during mechanical load application (using an initial design of loading device) have been demonstrated in our preliminary results. Dr. Jerban and his mentors, Drs. Chung, Ward, and Du, have designed a detailed training plan and assembled a strong team of advisors to guide Dr. Jerban through his career development plan towards becoming an independent investigator.