Water- and fat-suppressed proton projection MRI (WASPI) of rat femur bone
Water- and fat-suppressed proton projection MRI (WASPI) of rat femur bone
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DOI：
10.1002/mrm.21174
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发表时间：
2007-03-01
影响因子：
3.3
通讯作者：
Chesler, David A.
中科院分区：
文献类型：
--
作者：
Wu, Yaotang;Dai, Guangping;Chesler, David A.
研究人员经常通过Mu CT对大鼠进行研究，以探讨人类骨骼疾病的发病机制和治疗方法。然而，mCT测量只提供骨矿物质含量的信息，而不是固体基质的信息。CT扫描通常在松质骨上进行，松质骨含有大量的骨髓细胞、基质、水和脂肪，因此表观骨密度(BMD)不能反映基质中的矿物密度，而基质中的矿物晶体位于基质中。本研究利用水和脂肪抑制的固态质子投影成像技术(WASPI)对大鼠股骨标本的固体基质含量(胶原蛋白、紧密结合水和其他固定分子)进行成像，以满足样本量小和亚毫米分辨率要求的挑战。提出了一种恢复k空间中心区域的方法，该区域在获取自由感应衰落(FID)时总是在接收死区中丢失。利用这种方法，在减少梯度强度的少量径向投影下，对k空间原点附近的点进行采样。当前WASPI实验的典型扫描时间为2小时。获得了分辨率为0.4 mm、视野为12 mm的大鼠股骨质子固体矩阵图像。该方法为研究小动物的骨基质提供了一种非侵入性手段。
Investigators often study rats by mu CT to investigate the pathogenesis and treatment of skeletal disorders in humans. However, mu CT measurements provide information only on bone mineral content and not the solid matrix. CT scans are often carried out on cancellous bone, which contains a significant volume of marrow cells, stroma, water, and fat, and thus the apparent bone mineral density (BMD) does not reflect the mineral density within the matrix, where the mineral crystals are localized. Water- and fat-suppressed solid-state proton projection imaging (WASPI) was utilized in this study to image the solid matrix content (collagen, tightly bound water, and other immobile molecules) of rat femur specimens, and meet the challenges of small sample size and demanding submillimeter resolution. A method is introduced to recover the central region of k-space, which is always lost in the receiver dead time when free induction decays (FIDs) are acquired. With this approach, points near the k-space origin are sampled under a small number of radial projections at reduced gradient strength. The typical scan time for the current WASPI experiments was 2 hr. Proton solid-matrix images of rat femurs with 0.4-mm resolution and 12-mm field of view (FOV) were obtained. This method provides a noninvasive means of studying bone matrix in small animals.