For rat spinal magnetic resonance imaging (MRI) experiments, due to the lower main magnetic field strength, shallower detected depth and poor spatial compatibility of the traditional radio frequency (RF) coil, the image signal-to-noise ratio (SNR) of rat spinal was rather lower. In this paper, a RF coil for rat spinal MRI at 9.4 T was developed to improve the image quality and at the same time to avoid the space limitation while scanning in special conditions (cardiac catheterization, etc.). In this article, open birdcage structure was built and magnetic field distribution was calculated. The phantom and rat spine MRI imaging were experimented at 9.4 T to verify the advantage of the coil in rat spine MRI application.
Quantitative susceptibility mapping (QSM) can provide tissue susceptibility information and has been adapted for clinical research and diagnosis. QSM of monkey brain in vivo at 9.4 T has not been demonstrated so far. In this study 9.4 T in vivo monkey brain QSM was performed with 200 μm isotropic high-resolution. It was found that the inherent singularity problem for QSM diverged significantly at ultra-high image resolution during regularization process and resulted in severe image artifacts. The K-space division (TKD) was applied to eliminate the artifacts, with an optimal threshold level between 0.2 and 0.3. High resolution QSM of monkey brain in vivo can thus provide a novel tool for brain research.
【摘要】 目的 探讨常规MRI扫描及胰胆管造影（MRCP）对胆管梗阻性疾病的临床诊断价值。 方法 2006年4月-2010年6月，对59例胆管梗阻性疾病患者行常规MRI及MRCP检查，其中18例行动态增强扫描，并与临床诊断或手术、病理结果对照分析。MRCP采用不屏气厚层快速自旋回波（FSE）序列重度T2WI扫描，原始图像以最大信号强度投影（MIP）法进行三维重建。 结果 MRI及MRCP对胆管梗阻程度的判断和定位诊断准确率为100.0%，定性诊断准确率为91.5%，其中MRCP诊断胆管结石和恶性胆管梗阻的准确率分别为96.8%和86.9%。 结论 MRCP对胆管梗阻的定位诊断准确，结合3D原始图像、常规MRI扫描及动态增强扫描，对胆管结石和恶性胆管梗阻的定性诊断有很高的准确性。【Abstract】 Objective To evaluate the clinical diagnosis value of MRI and cholangiopancreatography (MRCP) in diagnosis of biliary obstructive disease. Methods Routine MRI and MRCP were performed on 59 patients between April 2006 and June 2010, in which dynamic enhance scan was performed on 18 patients. The results were compared with clinical diagnosis or surgical findings and pathological examination. Non-breath-hold thick slices heavy T2 weighted TSE sequence was used. The original images were reconstructed by using three-dimensional maximum-intensity-projection (MIP) algorithm. Results The accuracy of MRI and MRCP in the detection of the degree and level of bile duct obstruction was 100.0 % and the accuracy for evaluating the causes of obstruction was 91.5 %. In the diagnosis of bile duct stone and malignant biliary obstruction, the diagnostic rate of MRCP was 96.8 % and 86.9%. Conclusion Routine MRI and MRCP examination can accurately define the level of bile duct obstruction. Combining with the original images and routine images and dynamic enhance scan, the specificity for the diagnosis of bile duct stone and malignant biliary obstruction is high.