Nichols K, DePuey E G, Krasnow N, Lefkowitz D, Rozanski A
Department of Medicine, St. Luke's-Roosevelt Hospital, and Columbia University College of Physicians and Surgeons, New York, NY, USA.
J Nucl Cardiol. 1998 Jul-Aug;5(4):387-94. doi: 10.1016/s1071-3581(98)90144-1.
A method has been described for improving myocardial visibility on 99mTc-labeled sestamibi gated tomograms, even in the presence of severe hypoperfusion. It is essential to verify that images transformed in this manner truly depict the myocardium and do not contain image artifacts. This is especially important if transformed images are to be used to aid in the discernment of regional wall-motion abnormalities.
All radially detected maximum counts were mapped automatically to the same brightness level for each cinematic frame. This produced tomographic cine images strongly suggestive of myocardium that appeared to translate but not to brighten from diastole to systole. Transformed scintigrams were compared with echocardiographic cine images of horizontal long axis and short axis views for 40 patients. Echocardiograms were of sufficient quality to allow comparison of radial distances from left ventricular center to midmyocardium for 15 short axis images and 25 horizontal long axis images. Readings were graded independently for 10 territories on a five-point scale (normal, mild-to-moderate hypokinesis, severe hypokinesis, akinesis, dyskinesis) of regional wall motion of original and enhanced scintigrams and echocardiograms. Comparison of echocardiographic and single photon emission computed tomographic (SPECT) locations of midmyocardial horizontal long axis points yielded a root-mean-square error value of 1.5+/-0.6 pixels (average absolute error, 11%+/-5%). SPECT versus echocardiographic wall-motion readings were compared by means of contingency table analysis. The log-likelihood ratio (G2) was 109.3 (n = 364; df = 16) with probability of no association <10(-6). Although readings of unenhanced SPECT cine images agreed well with those of echocardiograms (G2 = 94.3; n = 350; df = 16; P < 10(-6), Pearson-corrected contingency coefficients indicated stronger association with echocardiograms of transformed tomograms than with readings of original scintigrams (0.57 versus 0.51). The McNemar chi2 test indicated this improvement to be significant. The strongest associations were found between readings of unenhanced and enhanced scintigrams. Overall, similar results were obtained for horizontal long axis and short axis territories when analyzed separately. Linear regression analysis indicated strong correlations (r = .80 to r = .92) of ejection fractions from unenhanced gated SPECT images, enhanced gated SPECT images, echocardiograms, and first-pass radionuclide angiograms with no significant differences among correlations.
Regional image enhancement succeeded in revealing shapes that genuinely represented myocardium in this population with hypoperfusion. Wall-motion conclusions were similar whether drawn from original or enhanced scintigrams, although enhancement significantly improved agreement with echocardiographic readings. Enhanced SPECT cine images allowed sensitive discrimination of regional wall-motion abnormalities, even in areas of severely hypoperfused myocardium, in excellent agreement with visual echocardiographic assessment for which myocardial visualization is independent of perfusion.
已描述了一种用于改善 99mTc 标记的 sestamibi 门控断层图像中心肌可视性的方法，即使在存在严重心肌灌注不足的情况下也是如此。必须验证以这种方式转换的图像是否真正描绘了心肌且不包含图像伪影。如果要使用转换后的图像来辅助识别局部室壁运动异常，这一点尤为重要。
对于每个电影帧，所有径向检测到的最大计数都自动映射到相同的亮度水平。这产生了强烈提示心肌的断层电影图像，这些图像似乎从舒张期到收缩期发生平移但未变亮。将 40 例患者的转换后的闪烁图与水平长轴和短轴视图的超声心动图电影图像进行比较。超声心动图质量足以允许对 15 个短轴图像和 25 个水平长轴图像从左心室中心到心肌中层的径向距离进行比较。对原始和增强闪烁图及超声心动图的 10 个区域的局部室壁运动，以五点量表（正常、轻度至中度运动减弱、重度运动减弱、运动消失、运动障碍）独立分级读数。心肌中层水平长轴点的超声心动图和单光子发射计算机断层扫描（SPECT）位置的比较产生了均方根误差值为 1.5±0.6 像素（平均绝对误差，11%±5%）。通过列联表分析比较 SPECT 与超声心动图的室壁运动读数。对数似然比（G2）为 109.3（n = 364；自由度 = 16），无关联的概率<10(-6)。尽管未增强的 SPECT 电影图像读数与超声心动图读数非常一致（G2 = 94.3；n = 350；自由度 = 16；P < 10(-6)），但经皮尔逊校正的列联系数表明，与转换后的断层图的超声心动图相比，与原始闪烁图读数的关联更强（0.57 对 0.51）。McNemar 卡方检验表明这种改善具有显著性。在未增强和增强闪烁图的读数之间发现了最强的关联。总体而言，分别分析水平长轴和短轴区域时获得了相似的结果。线性回归分析表明，未增强的门控 SPECT 图像、增强的门控 SPECT 图像、超声心动图和首次通过放射性核素血管造影的射血分数之间存在强相关性（r =.80 至 r =.92），相关性之间无显著差异。
区域图像增强成功地揭示了该心肌灌注不足人群中真正代表心肌的形状。无论从原始闪烁图还是增强闪烁图得出，室壁运动结论相似，尽管增强显著改善了与超声心动图读数的一致性。增强的 SPECT 电影图像能够敏感地辨别局部室壁运动异常，即使在心肌严重灌注不足的区域，与心肌可视化独立于灌注的超声心动图视觉评估高度一致。
