Department of Radiology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen OE, Denmark.
Ultraschall Med. 2010 Jun;31(3):296-301. doi: 10.1055/s-0029-1245457. Epub 2010 Jun 1.
To test the accuracy of spatial registration of real-time ultrasonography (US) fused with MRI in a phantom.
An US prototype system (LOGIQ, GE Healthcare) with incorporated software for fusion imaging was used to test two methods of co-registration in a phantom: co-registration from specific points, where common reference points identifiable on both MRI and US images were marked, and plane registration, where common planes identifiable on both MRI and US images were marked. In two series we performed co-registration from points and in one series we performed co-registration from planes. The accuracy of the co-registration was measured at 3 measuring points, defined before initiation of the study, and it was calculated as the root mean square deviation (RMSD), which corresponds to the standard deviation. It was measured in millimeters. Two observers each performed 30 co-registrations for each series, totaling 180 co-registrations. The difference between the methods and the observers was calculated using analysis of variance (two-way ANOVA).
Co-registration was significantly more accurate when using the measuring points as co-registration points than when using points covering a different area of the phantom (p < 0.0001). The mean calculated RMSD when using the measuring points as co-registration points was 1.3 mm (95 % CI: 1.1 - 1.5 mm), when using points away from the measuring points: 4.0 mm (95 % CI: 3.2 - 4.8 mm), and when using planes for the co-registration: 3.8 mm (95 % CI: 3.2 - 4.4 mm).
Image fusion involving real-time US has high accuracy and is easy to use in a phantom. Working within the area given by the co-registration points optimizes the accuracy. Image fusion is a promising tool for clinical US, since it provides the potential of benefiting from different imaging modalities in one examination.
在体模中测试实时超声（US）与 MRI 融合的空间配准准确性。
使用配备有融合成像软件的超声原型系统（LOGIQ，GE 医疗）测试两种配准方法：在体模中，通过特定点进行配准，即标记 MRI 和 US 图像上可识别的共同参考点；通过共同平面进行配准，即标记 MRI 和 US 图像上可识别的共同平面。在两个系列中，我们通过点进行配准，在一个系列中，我们通过平面进行配准。在研究开始之前定义了 3 个测量点，并通过均方根偏差（RMSD）进行配准准确性的测量，RMSD 对应标准差，以毫米为单位。两位观察者对每个系列的每个测量点分别进行了 30 次配准，总共进行了 180 次配准。使用方差分析（双因素方差分析）计算方法和观察者之间的差异。
当使用测量点作为配准点时，配准精度明显高于使用覆盖体模不同区域的点时（p<0.0001）。当使用测量点作为配准点时，计算得出的 RMSD 平均值为 1.3 毫米（95%置信区间：1.1-1.5 毫米），当使用远离测量点的点时，为 4.0 毫米（95%置信区间：3.2-4.8 毫米），当使用平面进行配准时，为 3.8 毫米（95%置信区间：3.2-4.4 毫米）。
实时 US 图像融合具有高精度，在体模中使用方便。在配准点给定的区域内工作可以优化准确性。图像融合是临床 US 的一种很有前途的工具，因为它有可能在一次检查中受益于不同的成像模式。
