Erdi Y E, Wessels B W, DeJager R, Erdi A K, Der L, Cheek Y, Shiri R, Yorke E, Altemus R, Varma V
Radiation Oncology & Biophysics Division, George Washington University Medical Center, Washington, DC 20037.
Cancer. 1994 Feb 1;73(3 Suppl):923-31. doi: 10.1002/1097-0142(19940201)73:3+<923::aid-cncr2820731327>3.0.co;2-f.
The use of computed tomography (CT) or magnetic resonance (MR) to overlay or register uptake patterns displayed by single-photon emission computed tomography (SPECT) with specific underlying anatomy has the potential to improve image interpretation and decrease diagnostic reading errors. The authors have developed a method that will allow the selection of a region of interest on MR or CT images that correlates with SPECT antibody images from the same patient. This method was validated first in phantom studies and subsequently was used on three patients with suspected colorectal carcinoma.
Two patients were injected with the technetium-99m-labeled 88BV59 immunoglobulin G human antibody, and the third patient was injected with the iodine-131-labeled 16.88 immunoglobulin M human antibody. CT or MR scans were obtained before antibody infusion, and subsequent SPECT scans were obtained on the first or fourth day after infusion. A customized body cast with landmarks was used for each patient during the CT, MR, and SPECT scans to match slice positions for all scanning modalities. Corresponding fiducial landmarks were identified on axial images. A computer graphics program was written to match and overlay corresponding landmarks for each imaging modality. The image registration accuracy was measured by comparing fiducial marker separations (center to center) on the registered scans. This separation uncertainty was 1-2 mm for CT-MR and 3-4 mm for CT-SPECT phantom studies.
For patient studies, the fiducial alignment uncertainty was 3-4 mm for axial CT-SPECT and MR-SPECT images, and 6-8 mm for sagittal CT-SPECT and MR-SPECT images. The accuracy of the anatomic alignment of the patient and image registration system was +/- 1 cm in the medial-lateral axis and +/- 2 cm in the cranial-caudal direction.
This type of image analysis may resolve uncertainties with the anatomic correlation of SPECT images that otherwise may be regarded as questionable when SPECT is used alone for radioimmunodiagnosis.
利用计算机断层扫描（CT）或磁共振成像（MR）将单光子发射计算机断层扫描（SPECT）显示的摄取模式与特定的基础解剖结构进行叠加或配准，有可能改善图像解读并减少诊断性阅片错误。作者开发了一种方法，可在MR或CT图像上选择与同一患者的SPECT抗体图像相关的感兴趣区域。该方法首先在体模研究中得到验证，随后应用于3例疑似结直肠癌患者。
2例患者注射了锝-99m标记的88BV59人免疫球蛋白G抗体，第3例患者注射了碘-131标记的16.88人免疫球蛋白M抗体。在注射抗体前进行CT或MR扫描，在注射后第1天或第4天进行后续的SPECT扫描。在CT、MR和SPECT扫描期间，为每位患者使用带有标记点的定制人体模型，以匹配所有扫描方式的切片位置。在轴向图像上识别相应的基准标记点。编写了一个计算机图形程序，以匹配和叠加每种成像方式的相应标记点。通过比较配准扫描上基准标记点的间距（中心到中心）来测量图像配准精度。对于CT-MR体模研究，这种间距不确定性为1 - 2毫米，对于CT-SPECT体模研究为3 - 4毫米。
对于患者研究，轴向CT-SPECT和MR-SPECT图像的基准对齐不确定性为3 - 4毫米，矢状面CT-SPECT和MR-SPECT图像的不确定性为6 - 8毫米。患者与图像配准系统的解剖对齐精度在内外侧轴上为±1厘米，在头尾方向上为±2厘米。
这种类型的图像分析可能解决SPECT图像解剖相关性方面的不确定性，否则当单独使用SPECT进行放射免疫诊断时，这些不确定性可能被视为有问题。
