Functional Imaging Division, Research Center for Innovative Oncology, National Cancer Center Hospital East, Kashiwanoha 6-5-1, Kashiwa, Chiba 277-8577, Japan.
Magn Reson Med Sci. 2013;12(2):95-103. doi: 10.2463/mrms.2012-0038. Epub 2013 May 10.
Simultaneous magnetic resonance (MR) imaging of multiple small animals in a single session increases throughput of preclinical imaging experiments. Such imaging using a 3-tesla clinical scanner with multi-array coil requires correction of intensity variation caused by the inhomogeneous sensitivity profile of the coil. We explored a method for correcting intensity that we customized for multi-animal MR imaging, especially abdominal imaging.
Our institutional committee for animal experimentation approved the protocol. We acquired high resolution T₁-, T₂-, and T₂*-weighted images and low resolution proton density-weighted images (PDWIs) of 4 rat abdomens simultaneously using a 3T clinical scanner and custom-made multi-array coil. For comparison, we also acquired T₁-, T₂-, and T₂*-weighted volume coil images in the same rats in 4 separate sessions. We used software created in-house to correct intensity variation. We applied thresholding to the PDWIs to produce binary images that displayed only a signal-producing area, calculated multi-array coil sensitivity maps by dividing low-pass filtered PDWIs by low-pass filtered binary images pixel by pixel, and divided uncorrected T₁-, T₂-, or T₂*-weighted images by those maps to obtain intensity-corrected images. We compared tissue contrast among the liver, spinal canal, and muscle between intensity-corrected multi-array coil images and volume coil images.
Our intensity correction method performed well for all pulse sequences studied and corrected variation in original multi-array coil images without deteriorating the throughput of animal experiments. Tissue contrasts were comparable between intensity-corrected multi-array coil images and volume coil images.
Our intensity correction method customized for multi-animal abdominal MR imaging using a 3T clinical scanner and dedicated multi-array coil could facilitate image interpretation.
在单次会话中同时对多个小动物进行磁共振（MR）成像可以提高临床前成像实验的通量。使用具有多通道线圈的 3 特斯拉临床扫描仪进行此类成像需要校正由于线圈不均匀灵敏度分布引起的强度变化。我们探索了一种针对多动物 MR 成像（特别是腹部成像）定制的校正强度的方法。
我们的动物实验机构委员会批准了该方案。我们使用 3T 临床扫描仪和定制的多通道线圈同时获取 4 只大鼠腹部的高分辨率 T₁-、T₂-和 T₂*-加权图像以及低分辨率质子密度加权图像（PDWI）。作为比较，我们还在 4 个单独的会话中对同一只大鼠进行了 T₁-、T₂-和 T₂*-加权容积线圈成像。我们使用内部创建的软件来校正强度变化。我们对 PDWI 应用阈值处理以产生仅显示信号产生区域的二进制图像，通过逐像素将低通滤波 PDWI 除以低通滤波二进制图像来计算多通道线圈灵敏度图，然后将未校正的 T₁-、T₂-或 T₂*-加权图像除以这些图来获得强度校正图像。我们比较了校正后的多通道线圈图像和容积线圈图像之间肝脏、椎管和肌肉之间的组织对比度。
我们的强度校正方法在所有研究的脉冲序列中表现良好，校正了原始多通道线圈图像中的变化，而不会降低动物实验的通量。校正后的多通道线圈图像和容积线圈图像之间的组织对比度相当。
我们针对使用 3T 临床扫描仪和专用多通道线圈进行多动物腹部 MR 成像定制的强度校正方法可以促进图像解释。
