Hambye Anne-Sophie E, Vervaet Ann M, Dobbeleir André A
Nuclear Medicine, University Hospital Tivoli, La Louvière, Belgium.
Nucl Med Commun. 2004 Apr;25(4):347-53. doi: 10.1097/00006231-200404000-00006.
Compared with other non-invasive methods for diagnosing coronary artery disease (CAD), myocardial perfusion imaging (MPI) suffers from some lack of specificity, especially in patients with a small heart. Allowing the assessment of perfusion on end diastolic images instead of summed images, gated single photon emission computed tomography (SPECT) constitutes an attractive method for increasing the accuracy of MPI. Scatter correction, known to improve image contrast, might also be interesting. The present study aimed at comparing scatter corrected to uncorrected gated MPI for CAD diagnosis.
The results for 100 patients referred for gated 99mTc sestamibi SPECT were analysed. They were divided into two subgroups according to their end systolic volume (ESV) measured by QGS analysis (group A, ESV > or =30 ml, n=65; group B, ESV <30 ml, n=35). For each patient, a total defect score (TDS) was quantified on four polar maps (uncorrected and scatter corrected, summed, and uncorrected and scatter corrected, end diastolic). The optimal TDS separating non-CAD from CAD patients was calculated by analysis of the receiver operating characteristic (ROC) curve for the four data sets, using the coronary angiogram as a 'gold standard'.
In the whole patient population, the accuracy of the uncorrected data was 67% for the end diastolic images and 71% for the summed images (sensitivity, 66% and 70%; specificity, 71% and 79%, respectively). After scatter correction, the accuracy did not change for the end diastolic data (accuracy, 67%; sensitivity, 63%; specificity, 93%) and increased to 74% for the summed data (sensitivity, 73%; specificity, 79%). In group A, the uncorrected data were 72% accurate for the end diastolic images and 78% for the summed images (sensitivity, 72% and 79%; specificity, 75% and 75%, respectively). After correction, the accuracy of end diastolic images increased to 77% (sensitivity, 77%; specificity, 75%), and did not change for the summed images (accuracy, 78%; sensitivity, 79%; specificity, 75%). In group B, the accuracy of uncorrected images amounted to 51% for both end diastolic and summed data (sensitivity, 48% and 40%; specificity, 60% and 80%, respectively). After correction, it increased to 57% for the end diastolic images and to 63% for the summed images (sensitivity, 48% and 64%; specificity, 80% and 60%, respectively).
Despite lower blurring on end diastolic compared with summed images, non-scatter corrected end diastolic data were least accurate for the diagnosis of coronary artery disease in patients with a high prevalence of disease. Scatter correction, by improving the delineation of perfusion defects, increased the accuracy of quantitative MPI for the diagnosis of CAD in a large number of patients, more particularly in those with a small heart.
与其他诊断冠状动脉疾病（CAD）的非侵入性方法相比，心肌灌注成像（MPI）存在一定的特异性不足，尤其是在心脏较小的患者中。门控单光子发射计算机断层扫描（SPECT）允许在舒张末期图像而非总合图像上评估灌注，是一种提高MPI准确性的有吸引力的方法。已知散射校正可改善图像对比度，可能也很有意义。本研究旨在比较经散射校正和未经校正的门控MPI在CAD诊断中的效果。
分析了100例接受门控99mTc 甲氧基异丁基异腈SPECT检查患者的结果。根据通过QGS分析测量的收缩末期容积（ESV）将他们分为两个亚组（A组，ESV≥30 ml，n = 65；B组，ESV < 30 ml，n = 35）。对于每位患者，在四张极坐标图上（未经校正和经散射校正的总合图像，以及未经校正和经散射校正的舒张末期图像）对总缺损评分（TDS）进行量化。以冠状动脉造影作为“金标准”，通过分析四个数据集的受试者操作特征（ROC）曲线，计算区分非CAD患者和CAD患者的最佳TDS。
在整个患者群体中，未经校正的数据在舒张末期图像上的准确性为67%，在总合图像上为71%（敏感性分别为66%和70%；特异性分别为71%和79%）。经散射校正后，舒张末期数据的准确性未改变（准确性为67%；敏感性为63%；特异性为93%），总合数据的准确性提高到74%（敏感性为73%；特异性为79%）。在A组中，未经校正的数据在舒张末期图像上的准确性为72%，在总合图像上为78%（敏感性分别为72%和79%；特异性分别为75%和75%）。校正后，舒张末期图像的准确性提高到77%（敏感性为77%；特异性为75%），总合图像的准确性未改变（准确性为78%；敏感性为79%；特异性为75%）。在B组中，未经校正的图像在舒张末期和总合数据上的准确性均为51%（敏感性分别为48%和40%；特异性分别为60%和80%）。校正后，舒张末期图像的准确性提高到57%，总合图像的准确性提高到63%（敏感性分别为48%和64%；特异性分别为80%和60%）。
尽管舒张末期图像的模糊程度低于总合图像，但未经散射校正的舒张末期数据在疾病患病率较高的患者中对冠状动脉疾病的诊断准确性最低。散射校正通过改善灌注缺损的描绘，提高了定量MPI在大量患者中诊断CAD的准确性，尤其是在心脏较小的患者中。
