Utsunomiya Daisuke, Tomiguchi Seiji, Shiraishi Shinya, Yamada Koichiro, Honda Tsuyoshi, Kawanaka Koichi, Kojima Akihiro, Awai Kazuo, Yamashita Yasuyuki
Diagnostic Imaging Center, Saiseikai Kumamoto Hospital, 5-3-1 Chikami, Kumamoto 861-4193, Japan.
Ann Nucl Med. 2005 Sep;19(6):485-9. doi: 10.1007/BF02985576.
Attenuation artifacts adversely affect the diagnostic accuracy of myocardial perfusion imaging. We assessed the clinical usefulness of X-ray CT based attenuation correction (AC) in patients undergoing myocardial perfusion imaging by comparing their myocardial AC- and non-corrected (NC) SPECT images with the coronary angiography (CAG).
We retrospectively reviewed the myocardial SPECT images of 30 patients (18 men, 12 women; mean age 68 years). Thirteen of 30 patients with coronary artery disease (CAD) and 17 without CAD were confirmed by CAG. They underwent sequential CT and myocardial SPECT imaging with thallium-201 (111 MBq) under an exercise or pharmacological stress protocol using our combined SPECT/ CT system. Two readers reviewed the myocardial SPECT images for the presence of CAD on a 4-point scale where 1 = normal, 2 = probably normal, 3 = probably abnormal, and 4 = abnormal. Two reading sessions were held. First, non-corrected (NC)-SPECT and second, AC-SPECT images using X-ray CT images were interpreted. Interobserver variability was assessed with kappa statistics. Diagnostic performance (accuracy) of coronary arterial stenosis was compared between AC- and NC-images.
Interobserver agreement for visual assessment was substantial or almost perfect. For AC-images, the observer consensus for analysis was 0.84 for the LAD-, 0.87 for the LCX-, and 0.71 for the RCA-territory. For NC-images, it was 0.91, 0.71, and 0.78. AC resulted in statistically significant improvements in overall diagnostic accuracy (sensitivity/ specificity/accuracy = 76%/93%/89%, 67%/86%/81%, respectively, for AC- and NC-images).
Because of an increase in the specificity, diagnostic accuracy was significantly increased on AC-images. These preliminary data suggest that X-ray CT based AC in myocardial SPECT imaging has the potential to develop into a reliable clinical technique.
衰减伪影对心肌灌注成像的诊断准确性有不利影响。我们通过比较心肌灌注成像患者的心肌衰减校正（AC）和未校正（NC）单光子发射计算机断层扫描（SPECT）图像与冠状动脉造影（CAG），评估基于X射线计算机断层扫描（CT）的衰减校正（AC）的临床实用性。
我们回顾性分析了30例患者（18例男性，12例女性；平均年龄68岁）的心肌SPECT图像。30例患者中13例经CAG证实患有冠状动脉疾病（CAD），17例无CAD。他们使用我们的联合SPECT/CT系统，在运动或药物负荷方案下，先后接受了CT和用铊-201（111MBq）进行的心肌SPECT成像。两名阅片者以4分制对心肌SPECT图像进行CAD存在情况的评估，1分=正常，2分=可能正常，3分=可能异常，4分=异常。进行了两次阅片。第一次，解读未校正（NC）-SPECT图像；第二次，解读使用X射线CT图像的AC-SPECT图像。用kappa统计量评估观察者间的变异性。比较AC图像和NC图像之间冠状动脉狭窄的诊断性能（准确性）。
观察者间视觉评估的一致性为中度或几乎完全一致。对于AC图像，左前降支（LAD）区域分析的观察者共识为0.84，左旋支（LCX）区域为0.87，右冠状动脉（RCA）区域为0.71。对于NC图像，分别为0.91、0.71和0.78。AC使总体诊断准确性有统计学意义的提高（AC图像和NC图像的敏感性/特异性/准确性分别为76%/93%/89%、67%/86%/81%）。
由于特异性增加，AC图像的诊断准确性显著提高。这些初步数据表明，心肌SPECT成像中基于X射线CT的AC有发展成为一种可靠临床技术的潜力。
