Shimada Y, Uemura K, Ardekani B A, Nagaoka T, Ishiwata K, Toyama H, Ono K, Senda M
Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1 Nakachou, 173, Itabashiku, Japan.
J Neurosci Methods. 2000 Aug 15;101(1):1-7. doi: 10.1016/s0165-0270(00)00206-5.
In positron emission tomography (PET) studies of diseased animals, it is very useful to have accurate anatomical information as a reference. In human studies, anatomical information is usually obtained from magnetic resonance imaging (MRI) of the subject with retrospective registration of the subject's PET image to the MRI. A number of PET-MRI registration techniques are used for this purpose. However, the utility of these methods has not been tested for animals image registration. This paper studies the feasibility of applying two currently used human brain PET-MRI registration techniques to cat brain images.
Three cats were anesthetized with isoflurane gas, and PET images were acquired with H(2)(15)O, benzodiazepine receptor ligand 11C-flumazemil (FMZ), dopamine receptor ligand 11C-nemonapride (NEM) and fluorodeoxy glucose (18F-FDG). The four PET scans were acquired consecutively within the same day while the cat remained fixed in the scanner. We also obtained T1-weighted and T2-weighted MRI of the cats in a 4.7 T unit. The PET images were registered to MRI using two human brain registration techniques: a semi-automatic method (SAM), which is a two-step method based on the extraction of the midsagittal plane, and an automatic method (AMIR) method that minimizes PET pixel variance within spatially connected segments determined by MRI.
T2-weighted MRI provided better structural information than T1 MRI. FMZ did, while FDG or H(2)O PET images did not, provide a structural outline of the brain. The FMZ PET image was registered to MRI satisfactorily using SAM. The striatum visualized in nemonapride PET image re-sliced with the same parameters matched the striatum identified in T2-weighted MRI. Registration by AMIR was successful by inspection for FMZ, FDG or H(2)O PET images in only one of the three cats. The registration error of SAM was estimated to be less than 2 mm or 2 degrees.
A satisfactory registration of FMZ-PET to T2-weighted MRI of the cat brain was obtained by a two-step manual registration technique. This will enhance the usefulness of PET in the field of cerebral pathophysiology.
在对患病动物进行正电子发射断层扫描（PET）研究时，拥有准确的解剖学信息作为参考非常有用。在人体研究中，解剖学信息通常从受试者的磁共振成像（MRI）中获取，并将受试者的PET图像与MRI进行回顾性配准。为此使用了多种PET-MRI配准技术。然而，这些方法在动物图像配准方面的效用尚未得到测试。本文研究了将两种目前用于人类脑PET-MRI配准的技术应用于猫脑图像的可行性。
用异氟烷气体麻醉三只猫，并用H₂¹⁵O、苯二氮䓬受体配体¹¹C-氟马西尼（FMZ）、多巴胺受体配体¹¹C-奈莫必利（NEM）和氟脱氧葡萄糖（¹⁸F-FDG）采集PET图像。在同一天内连续采集四次PET扫描，期间猫保持固定在扫描仪中。我们还在4.7T设备中获取了猫的T1加权和T2加权MRI。使用两种人类脑配准技术将PET图像与MRI配准：一种半自动方法（SAM），这是一种基于中矢状面提取的两步法；以及一种自动方法（AMIR），该方法在由MRI确定的空间连接段内最小化PET像素方差。
T2加权MRI比T1 MRI提供了更好的结构信息。FMZ能提供脑的结构轮廓，而FDG或H₂O PET图像则不能。使用SAM可将FMZ PET图像令人满意地与MRI配准。用相同参数重新切片的奈莫必利PET图像中显示的纹状体与T2加权MRI中识别的纹状体匹配。通过AMIR进行的配准在三只猫中只有一只的FMZ、FDG或H₂O PET图像检查时成功。SAM的配准误差估计小于2毫米或2度。
通过两步手动配准技术实现了FMZ-PET与猫脑T2加权MRI的满意配准。这将提高PET在脑病理生理学领域的效用。
