Sabondjian Eric, Stodilka Robert Z, Belhocine Tarik, King Martin E, Wisenberg Gerald, Prato Frank S
Lawson Health Research Institute, Imaging Program, London, Ontario N6A 4V2, Canada.
Nucl Med Commun. 2009 Sep;30(9):718-26. doi: 10.1097/MNM.0b013e32832eabec.
Image truncation in nuclear medicine is a common problem that can lead to artifacts in reconstructed images. We evaluate a modified single-photon emission computed tomography/computed tomography (SPECT/CT) acquisition and reconstruction method for truncated SPECT, which is guided by nontruncated CT. The method nearly eliminates truncation errors, and is ideal for cardiac imaging. We demonstrate its application on phantom and clinical cardiac SPECT/CT scans.
Tc-MIBI (2-methoxy isobutyl isonitrile) SPECT/CT scans were acquired on 14 patients, and on an anthropomorphic cardiac chest phantom. The original 34 x 34 cm field-of-view (FOV) projections were truncated to simulate a small 16 x 16 cm FOV acquisition. Data were reconstructed in three ways: (i) nontruncated and standard reconstruction (NTOSEM), which was our gold standard; (ii) truncated and standard reconstruction (TOSEM); and (iii) truncated and a modified reconstruction (TMOSEM). TMOSEM and TOSEM were both compared with NTOSEM by comparing relative count ratios in the heart, looking at the change in perfusion defect size, and comparing pixel correlation coefficients.
Compared with NTOSEM, the use of TOSEM for small FOV clinical imaging incurred an average count ratio error greater than 100%, and decreased the calculated defect size by 17.13%. For TMOSEM, the average count ratio error was only 8.9%, and the defect size was only decreased by 0.19% compared with NTOSEM. When we plotted TOSEM against NTOSEM a correlation coefficient of 0.734 was calculated, and when we plotted TMOSEM against NTOSEM a correlation coefficient of 0.996 was measured. Comparing NTOSEM with TOSEM in the phantom study produced an average count ratio error greater than 100%. TMOSEM produced an error of 4.3% compared with NTOSEM.
Projection truncation due to small FOV cameras in cardiac SPECT/CT can lead to significant errors. TMOSEM guided by nontruncated CT reconstruction shows promise in reducing these errors.
核医学中的图像截断是一个常见问题，可能导致重建图像中出现伪影。我们评估了一种改进的单光子发射计算机断层扫描/计算机断层扫描（SPECT/CT）采集和重建方法，用于截断的SPECT，该方法由未截断的CT引导。该方法几乎消除了截断误差，非常适合心脏成像。我们展示了其在体模和临床心脏SPECT/CT扫描中的应用。
对14例患者和一个拟人化心脏胸部体模进行了锝-甲氧基异丁基异腈（Tc-MIBI）SPECT/CT扫描。将原始34×34 cm视野（FOV）投影截断，以模拟16×16 cm小视野采集。数据以三种方式重建：（i）未截断的标准重建（NTOSEM），这是我们的金标准；（ii）截断的标准重建（TOSEM）；（iii）截断的改进重建（TMOSEM）。通过比较心脏中的相对计数率、观察灌注缺损大小的变化以及比较像素相关系数，将TMOSEM和TOSEM与NTOSEM进行比较。
与NTOSEM相比，在小视野临床成像中使用TOSEM导致平均计数率误差大于100%，并使计算出的缺损大小减少了17.13%。对于TMOSEM，平均计数率误差仅为8.9%，与NTOSEM相比，缺损大小仅减少了0.19%。当我们绘制TOSEM与NTOSEM的关系图时，计算出的相关系数为0.734，当我们绘制TMOSEM与NTOSEM的关系图时，测量出的相关系数为0.996。在体模研究中，将NTOSEM与TOSEM进行比较，平均计数率误差大于100%。与NTOSEM相比，TMOSEM产生的误差为4.3%。
心脏SPECT/CT中小视野相机导致的投影截断会导致显著误差。由未截断的CT重建引导的TMOSEM在减少这些误差方面显示出前景。
