Giorgetti Assuero, Marzullo Paolo, Sambuceti Gianmario, Di Quirico Simona, Kusch Annette, Landi Patrizia, Salvadori Piero Antonio, Pisani Patrizia, L'abbate Antonio
CNR Institute of Clinical Physiology, Pisa, Italy.
J Nucl Cardiol. 2004 Mar-Apr;11(2):142-51. doi: 10.1016/j.nuclcard.2003.12.011.
Positron emission tomography (PET) flow/metabolic mismatch is considered the nuclear medicine gold standard for the assessment of myocardial viability. The aim of this study was to investigate whether baseline/nitrate technetium 99m tetrofosmin single photon emission computed tomography (SPECT) mismatch may provide equivalent clinical information.
We studied 23 patients (aged 62 +/- 10 years, 19 men) with previous myocardial infarction (16 anterior, 4 inferior, and 3 anterior plus inferior) and postischemic heart failure (gated SPECT [G-SPECT] ejection fraction, 26% +/- 8%). All patients underwent Tc-99m tetrofosmin G-SPECT at rest and after nitrates (intravenous isosorbide dinitrate, 0.2 mg/mL, 10 mL/h) as well as a fluorine 18 fluoro-2-deoxy-d-glucose (FDG) PET scan. Regional wall motion analysis was performed with quantitative G-SPECT (QGS). Myocardial dysfunction was defined as a regional QGS score of 2 or greater. Regional perfusion was assessed by quantitative perfusion score (QPS) providing percent Tc-99m tetrofosmin uptake in a 20-segment model. Semiquantitative analysis of FDG uptake was performed by use of polar maps generated by Siemens ECAT HR + software. In areas with a perfusion rate lower than 80%, PET viability was identified by a normalized FDG percent uptake/baseline Tc-99m tetrofosmin percent uptake ratio greater than 1.2. We analyzed 460 segments; 298 (64%) were dysfunctional by QGS analysis. Of these, 170 were viable by PET imaging whereas 128 were nonviable. Regional Tc-99m tetrofosmin uptake was higher in viable than in nonviable segments both at rest (60% +/- 24% vs 42% +/- 12%, P <.01) and after nitrates (67% +/- 20% vs 41% +/- 18%, P <.01). According to receiver operating characteristic curve analysis, a cutoff value of 63% for resting as well as post-nitrate G-SPECT provided the highest diagnostic accuracy for the detection of myocardial viability (67% and 72% at rest and after nitrates, respectively). When the same algorithm used for the comparison with PET (normalized nitrate percent uptake/baseline percent uptake) was applied to G-SPECT, we obtained the highest agreement with PET (accuracy, 93%; sensitivity, 95%; specificity, 92%).
In patients with severe left ventricular dysfunction, perfusion data alone, both at rest and after nitrates, do not allow an accurate estimate of myocardial viability. In dysfunctioning segments, the analysis of rest/post-nitrate Tc-99m tetrofosmin mismatch provides results similar to those obtained by PET flow/metabolic mismatch.
正电子发射断层扫描（PET）血流/代谢不匹配被认为是评估心肌存活的核医学金标准。本研究的目的是调查基线/硝酸盐锝99m替曲膦单光子发射计算机断层扫描（SPECT）不匹配是否能提供等效的临床信息。
我们研究了23例患者（年龄62±10岁，19例男性），这些患者既往有心肌梗死（16例前壁、4例下壁、3例前壁加下壁）和缺血后心力衰竭（门控SPECT[G-SPECT]射血分数为26%±8%）。所有患者均接受静息和硝酸盐（静脉注射硝酸异山梨酯，0.2mg/mL，10mL/h）注射后的锝99m替曲膦G-SPECT检查以及氟18氟-2-脱氧-D-葡萄糖（FDG）PET扫描。采用定量G-SPECT（QGS）进行区域壁运动分析。心肌功能障碍定义为区域QGS评分为2或更高。通过定量灌注评分（QPS）评估区域灌注，QPS在20节段模型中提供锝99m替曲膦摄取百分比。通过使用西门子ECAT HR +软件生成的极坐标图对FDG摄取进行半定量分析。在灌注率低于80%的区域，通过标准化的FDG摄取百分比/基线锝99m替曲膦摄取百分比比值大于1.2来确定PET存活情况。我们分析了460个节段；通过QGS分析，其中298个（64%）功能异常。在这些节段中，170个通过PET成像显示存活，而128个无存活。静息时（60%±24%对42%±12%，P<.01）和硝酸盐注射后（67%±20%对41%±18%，P<.01），存活节段的区域锝99m替曲膦摄取均高于无存活节段。根据受试者工作特征曲线分析，静息和硝酸盐注射后G-SPECT的截断值为63%时，对心肌存活检测的诊断准确性最高（静息和硝酸盐注射后分别为67%和72%）。当将用于与PET比较的相同算法（标准化硝酸盐摄取百分比/基线百分比摄取）应用于G-SPECT时，我们获得了与PET的最高一致性（准确性，93%；敏感性，95%；特异性，92%）。
在严重左心室功能障碍的患者中，仅静息和硝酸盐注射后的灌注数据无法准确估计心肌存活情况。在功能异常的节段中，静息/硝酸盐注射后锝99m替曲膦不匹配分析提供的结果与PET血流/代谢不匹配分析获得的结果相似。
