心肌活力测定的研究进展

心肌灌注显像的定量分析、门控心肌灌注显像、^18F-氟代脱氧葡萄糖（^18F-FDG）＋^90Tc^m-甲氧基异丁基异腈（^99Tc-m-MIBI）双核素同时采集（DISA）、介入心动图和核磁共振显像（MRI）技术的进展提高了对心肌活力的认识，介入心动图、心肌灌注显像、心肌代谢显像的结合应用提高了心肌活力测定的准确性。心肌活力测定可确定能得益于冠状动脉再血管化治疗的患者，并可预测术后左室射血分数的增加和心力衰竭症状的改善。     

硝酸甘油介入99Tcm-tetrofosmin SPECT与18F-FDG PET显像评估心肌活力比较

目的 比较硝酸甘油介入^99Tc^m-tetrofosmin SPECT心肌血流灌注显像与^18F-FDG PET心肌代谢显像评估心肌活力的价值。方法 既往有心肌梗死史伴左心功能不全经冠状动脉造影确诊为冠心病的患者36例，行二日法静息和硝酸甘油介入^99Tc^m-tetrofosmin SPECT显像，并在1周内再行^18F-FDG PET心肌代谢显像及静息超声心动图检查。将左心室分成13个节段，分析超声心动图室壁运动，并分析相同节段^99Tc^m-tetrofosmin与^18F-FDG的相对摄取比值，以^18Tc^m-tetrofosmin摄取比值55％，^18F—FDG摄取比值50％为判断心肌活力有无的阈值。以k统计比较3种方法的一致性。结果 超声心动图示131个节段呈无运动或反向运动。^99Tc^m-tetrofosmin静息显像示其中78个节段（60％）心肌有活力，53个节段（40％）无活力。该53个节段中14个（26％）在硝酸甘油介入后可见再填充，余39个节段无改变。在^18F—FDGPET显像中，硝酸甘油介入显像再填充节段的心肌放射性摄取明显增高。再填充节段与无填充节段比较，心肌FDG摄取分别为（76±15）％和（58±17）％，差异有统计学意义（P〈0．01）。硝酸甘油介入显像中，92个心肌节段（70％）有活力，39个无活力。tetrofosmin静息显像评估心肌活力与FDG PET显像比较，k值为0．35，而硝酸甘油介入^99Tc^m-tetrofosmin SPECT与^18F—FDGPET显像结果比较，k值为0．53。结论 硝酸甘油介入^99Tc^m-tetrofosmin SPECT显像可提高对心肌活力的检测能力，与^18F—FDG PET心肌代谢显像有很好的一致性。     

18F-氟脱氧葡萄糖符合线路诊断心肌梗死后的心肌活力

目的利用^18F-氟脱氧葡萄糖（^18F-FDG）符合线路空腹，糖负荷代谢显像和^99mTc-甲氧基异丁基异腈（^99mTc-MIBI）来判断心肌梗死后心肌的活力。方法24例心肌梗死患者进行血管造影、^99mTc-MIBI负荷和（或）静息血流灌注检查、^18F-FDG符合线路心肌代谢显像（空腹-葡萄糖负荷显像一日法）。结果^99mTc-MIBI灌注显像发现的27个缺血节段在空腹和糖负荷均有^18F-FDG的摄取，心肌存活；22个缺血节段在空腹和糖负荷显像后没有^18F-FDG的摄取，心肌没有活力。空腹状态心肌对^18F-FDG摄取较少，有活力的心肌缺血节段显示特别清晰，图像质量较差；葡萄糖负荷后活力心肌摄取^18F-FDG，图像质量有明显改善。结论空腹和糖负荷都可判断心肌活力，空腹显像时图像的质量稍差，糖负荷能够提高图像质量。     

硝酸甘油介入99Tcm-MIBI SPECT心肌显像对PTCA决策的影响

目的评价硝酸甘油(NTG)介入99Tcm-甲氧基异丁基异腈(MIBI) SPECT心肌显像对心肌梗死患者行经皮冠状动脉腔内成形术(PTCA)决策的影响.方法 51例心肌梗死患者PTCA前1周内行99Tcm-MIBI静息和NTG介入心肌显像,术后2～3个月内复查静息心肌显像,并进行对比分析.结果 51例患者共141个心肌灌注异常节段,其中术后74个节段心肌血流灌注改善,治疗有效率为52.48%.术前NTG介入显像表现为可逆性缺损79个节段,术后84.81%(67个)节段心肌灌注改善,其中有明显填充的58个节段,术后全部灌注改善.NTG介入显像表现为不可逆性缺损的62个节段,有11.29 %(7个)节段术后心肌灌注改善.NTG介入显像检测心肌存活的准确性为86.52%.结论 NTG介入99Tcm-MIBI SPECT心肌显像对患者行PTCA起重要的决策作用.     

硝酸甘油介入~(99)Tc~m-MIBISPECT心肌显像对PTCA决策的影响

目的　评价硝酸甘油 (NTG)介入99Tcm 甲氧基异丁基异腈 (MIBI)SPECT心肌显像对心肌梗死患者行经皮冠状动脉腔内成形术 (PTCA)决策的影响。方法　 5 1例心肌梗死患者PTCA前 1周内行99Tcm MIBI静息和NTG介入心肌显像 ,术后 2～ 3个月内复查静息心肌显像 ,并进行对比分析。结果　 5 1例患者共 14 1个心肌灌注异常节段 ,其中术后 74个节段心肌血流灌注改善 ,治疗有效率为5 2 4 8%。术前NTG介入显像表现为可逆性缺损 79个节段 ,术后 84 81% (6 7个 )节段心肌灌注改善 ,其中有明显填充的 5 8个节段 ,术后全部灌注改善。NTG介入显像表现为不可逆性缺损的 6 2个节段 ,有 11 2 9% (7个 )节段术后心肌灌注改善。NTG介入显像检测心肌存活的准确性为 86 5 2 %。结论NTG介入99Tcm MIBISPECT心肌显像对患者行PTCA起重要的决策作用。     

门控心肌灌注断层显像与超声心动图评价左室功能和左室容积的比较

门控心肌灌注断层(GSPECT)显像可同步评价左室心肌血流灌注和左室功能状况,此技术所测的左室射血分数(LVEF)、舒张末期容积(EDV)和收缩末期容积(ESV)的准确性报道尚少。因此,使用不同的显像剂和显像方案行GSPECT显像,将其测定的结果与超声心动图(ECG)进行比较。方法:109例冠心病患者(男53例,女56例)于15d内分别行GSPECT显像和ECG检查。其中42例采用201　Tl负荷-再分布显像方案,55例行一天法99Tcm-甲氧基异丁基异腈(99Tcm-MIBI)或99Tcm-tetrofosmin负荷-静息显像方案,余12例行静息201　Tl-负荷99Tcm-MIBI显像方案。每个…     

小剂量多巴酚丁胺介入~(99)Tc~m-MIBI和~(201)Tl再注射心肌显像检测存活心肌的初步研究

小剂量多巴酚丁胺 (Ｄｏｂ)核素心室显像和超声心动图对检测存活心肌是有临床价值的无创性方法[1 ,2 ] 。我们用小剂量Ｄｏｂ介入后2 0 1 Ｔｌ再注射显像和99Ｔｃｍ-甲氧基异丁基异腈 (ＭＩＢＩ)显像对其检测心肌活力的效能进行了研究 ,现报道如下。资料与方法一、病例资料2 0 1 Ｔｌ再注射显像组 :32例陈旧性心肌梗死 (ＯＭＩ)患者 ,男 2 4例 ,女 8例 ,年龄(5 5± 7,46～ 6 8)岁。均于 2周内分别进行潘生丁负荷、再注射2 0 1 Ｔｌ显像和小剂量Ｄｏｂ介入2 0 1 Ｔｌ再注射显像 (ＴＩ-Ｄｏｂ)、心电图与超声心动图检查等。心肌梗死病程(18 3…     

双核素显像评价PCI术后心肌代谢与血流灌注

目的: 探讨18F-FDG葡萄糖代谢显像结合99mTc-MIBI静息灌注显像评价急性心肌梗塞(AMI)患者经皮冠心病介入治疗(PCI)后的心肌代谢及血流灌注.材料和方法: 用符合线路ECT对25例AMI患者在PCI术后2周行18F-FDG及99mTc-MIBI显像,通过圆周剖面半定量分析,评价局部心肌灌注、代谢和超声心动图检测的室壁运动功能之间的关系.结果: 术后2周运动正常心肌节段99mTc-MIBI%与18F-FDG%摄取值分别为83.7±15.7、89.4±13.6,比运动减弱节段(68.5±17.3、71.2±18.6)和无运动节段(32.3±14.9、56.1±18.8)高,(P<0.01);3个月后运动恢复心肌节段(n=67) MIBI%、FDG%分别为43.6±14.6、71.1±17.9高于运动未恢复节段(n=49) 的31.5±13.4、48.0±14.3高(P<0.01).室壁运动评分指数(WMSI)与99mTc-MIBI缺损%成正相关(r=0.791).结论: 心肌血流灌注、代谢显像能预测室壁运动改善,可用于临床判断PCI术后疗效.     

肥厚梗阻型心肌病化学消融术后的心肌灌注与代谢同时显像

目的 了解肥厚梗阻型心肌病(HOCM)患者行经皮室间隔心肌化学消融术(PTSMA)前后心肌灌注和代谢的变化.方法 对31例HOCM患者在PTSMA前进行了99Tcm-甲氧基异丁基异腈(MIBI)灌注显像和18F-脱氧葡萄糖(FDG)代谢显像,其中15例进行术后急性期(3～7d)99Tcm-MIBI灌注显像和18F-FDG代谢显像复查,以半定量记分法评价各室壁节段灌注和代谢变化情况.结果 99Tcm-MIBI灌注显像:90.3%(28/31)的HOCM患者PTSMA术前室间隔放射性浓聚,PTSMA术后80.0%(12/15)的HOCM患者室间隔灌注有不同程度的减低;18F-FDG代谢显像在PTSMA术前54.8%(17/31)的患者表现为代谢异常,术后33.3%(5/15)的患者代谢异常降低,以间隔后段最为明显.结论 99Tcm-MIBI SPECT灌注显像可作为评价PTSMA术后效果的重要手段.18F-FDG代谢显像有重要的参考价值.     

肥厚梗阻型心肌病化学消融术后的心肌灌注与代谢同时显像

目的 了解肥厚梗阻型心肌病(HOCM)患者行经皮室间隔心肌化学消融术(PTSMA)前后心肌灌注和代谢的变化.方法 对31例HOCM患者在PTSMA前进行了99Tcm-甲氧基异丁基异腈(MIBI)灌注显像和18F-脱氧葡萄糖(FDG)代谢显像,其中15例进行术后急性期(3～7d)99Tcm-MIBI灌注显像和18F-FDG代谢显像复查,以半定量记分法评价各室壁节段灌注和代谢变化情况.结果 99Tcm-MIBI灌注显像:90.3%(28/31)的HOCM患者PTSMA术前室间隔放射性浓聚,PTSMA术后80.0%(12/15)的HOCM患者室间隔灌注有不同程度的减低;18F-FDG代谢显像在PTSMA术前54.8%(17/31)的患者表现为代谢异常,术后33.3%(5/15)的患者代谢异常降低,以间隔后段最为明显.结论 99Tcm-MIBI SPECT灌注显像可作为评价PTSMA术后效果的重要手段.18F-FDG代谢显像有重要的参考价值.     

F-18 fluoro deoxyglucose SPECT for assessment of myocardial viability

Identification of myocardial viability in hypokinetic segments is important in patients with ischemic cardiomyopathy because systolic dysfunction improves with revascularization. Positron emission tomography (PET) F-18 fluoro deoxyglucose (FDG) uptake has been demonstrated as an accurate indicator of metabolically active and thus viable myocardium. F-18 FDG single photon emission computed tomography (SPECT) has recently been introduced and offers a technically easier and less costly alternative to PET imaging for determination of myocardial viability. A body of literature demonstrates that F-18 FDG SPECT can reliably be performed with SPECT hardware equipped with 511-keV collimators, which provides an accurate assessment of myocardial viability. F-18 FDG SPECT offers data similar to those offered by F-18 FDG PET and compares favorably with other imaging modalities, including rest-redistribution and stress-reinjection thallium-201 myocardial perfusion imaging, gated technetium 99m SPECT, and low-dose dobutamine echocardiography.     

99mTc-MIBI myocardial perfusion imaging in myocarditis

Myocardial perfusion imaging with technetium-99m-labelled methoxyisobutyl isonitrile single photon emission computed tomography (99mTc-MIBI SPECT) has proven to be an important clinical procedure in assessing the severity of myocardial ischaemia. The uptake and clearance of 99mTc-MIBI by the myocardium is affected by cell viability and membrane integrity. Consequently, infectious diseases, such as myocarditis, may also affect myocardial perfusion by inducing local inflammation and necrosis. We compared 99mTc-MIBI myocardial perfusion imaging with other heart monitoring methods in order to assess its value in the diagnosis of children with Coxsackie viral myocarditis. We examined 46 patients (age, 3-12 years) with Coxsackie viral myocarditis using 99mTc-MIBI myocardial perfusion imaging and compared the perfusion data with myocardial enzymes, electrocardiographic findings and echocardiography. Regions of hypoperfusion were found in all 46 patients. Seventeen patients (37%) showed two or more areas of diminished perfusion. Myocardial hypoperfusion was mild-to-moderate (<30%) in 33 (72%) patients and severe (>30%) in 13 (28%) patients. Characteristic creatine-kinase isoenzyme (CK-MB) increases, ST-T segment changes and diminished heart function were significantly correlated with reduced myocardial perfusion (all comparisons P<0.05). The results of this study suggest that the presence of myocardial uptake of 99mTc-MIBI may be a marker of myocardial inflammation and necrosis. All 46 patients with Coxsackie viral myocarditis showed a certain degree of reduced perfusion. When the perfusion findings were compared with other parameters, it was shown that myocardial enzyme levels, ST-T segment changes and left ventricular function correlated well with the 99mTc-MIBI-established perfusion defect severity. 99mTc-MIBI SPECT imaging is therefore helpful in providing additional diagnostic information in patients with Coxsackie viral myocarditis.     

Gated 99mTc-tetrofosmin and 18F-FDG studies: a comparison of single-acquisition and separate-acquisition protocols

18F-FDG is a well-established tracer for evaluating myocardial viability, as is (99m)Tc-tetrofosmin (TET) for evaluating myocardial perfusion. Dual-isotope single-acquisition (DISA) studies using a (99m)Tc perfusion agent and (18)F-FDG have been performed to evaluate myocardial viability. The purpose of this investigation was to determine whether there is a difference in the results of gated SPECT DISA, compared with gated SPECT DIDA (dual-isotope dual-acquisition) studies using (99m)Tc-TET/(18)F-FDG and a high-energy collimated dual-head SPECT system. METHODS: We prospectively studied 13 patients with depressed left ventricular function using both acquisition protocols. Summed rest scores were calculated for both (99m)Tc and (18)F-FDG studies using a 12-segment model and a 5-grade severity score. Images were evaluated by a single reader who did not know whether the images were acquired separately or simultaneously. RESULTS: The concordance of DISA and DIDA protocols for (99m)Tc-TET when allowing no difference in the SRS was 57%, or 89 of 156 segments. The concordance of DISA and DIDA protocols for (18)F-FDG was 86%, or 134 of 156 segments. The concordance of segments determined to be viable versus nonviable was 92%, or 143 of 156 segments. Ejection fraction measurements obtained by gated (99m)Tc-TET studies correlated strongly with those obtained by gated (18)F-FDG studies. CONCLUSION: A high concordance for (18)F-FDG studies was shown between gated DISA and gated DIDA. A lower concordance was shown between gated DISA and gated DIDA studies using (99m)Tc-TET, most likely because of downscatter from (18)F into the (99m)Tc window. An excellent concordance was demonstrated between the 2 techniques for viability assessment. The gated (99m)Tc-TET/(18)F-FDG DISA protocol can be both a reliable and an efficient way to evaluate myocardial function, perfusion, and viability.     

Assessment of cardiac function and myocardial metabolism by nuclear medicine]

Simultaneous assessment of myocardial perfusion and cardiac function came to be possible by 99mTc myocardial perfusion agents. We can use ECG-gated SPECT and first pass radionuclide angiocardiography for it. ECG-gated SPECT made it possible to assess wall motion using wall thickening and QGS (quantitative gated SPECT) analysis, which are useful in various clinical situations. First pass radionuclide angiocardiography gives good assessment of cardiac function during stress, and supports the diagnosis of myocardial ischemia. On the other hand, the assessment of myocardial metabolism is another specific feature of nuclear cardiology. 123I-BMIPP SPECT is applicable to various cardiac diseases such as ischemic heart disease, and 18F-FDG PET has been considered as the gold standard of myocardial viability. Recently, gamma camera for 18F-FDG imaging has been developed, which may make FDG imaging more popular.     

Evaluation of the clinical value of combination of 99mTc-MIBI myocardial SPECT and 18F-FDG PET in assessing myocardial viability.

PURPOSE: To evaluate the value of 18F-FDG PET metabolic imaging and 99mTc-MIBI SPECT in the identification of myocardial viability in patients with previous myocardial infarction and left ventricular dysfunction. METHODS: 18F-FDG PET (made in China) and 99mTc-MIBI SPECT were performed in 60 patients (pts) (age 54+/-9 yr) with myocardial infarction before revascularization. Before and after revascularization, LVEF and wall motion were measured with echocardiography in 36 pts (Group A), and myocardial perfusion was evaluated in 24 pts (Group B). RESULTS: According to the interpretation of perfusion and metabolic images, myocardial segments were classified into mismatch (MM): reduced myocardial perfusion and normal FDG uptake or match (M): reduced perfusion and FDG uptake. Out of 264 segments with hypoperfusion, 145 (54.9%) were MM, suggesting viable myocardium (G-A1 and G-B1), 119 (45.1%) were M, suggesting necrosis (G-A2 and G-B2). After revascularization, LVEF was increased in G-A1 (49+/-15% vs. 59+/-7%, p<0.05), and in G-B1 (50+/-8% vs. 59+/-12%, p<0.05), but was not improved in G-A2 and G-B2. LVEDD was decreased in G-A1 and G-B1 (p<0.05) and was unchanged in G-A2 and G-B2. The positive predictive value (PPV) of FDG PET for improvement of regional wall motion after revascularization was 88%, and the negative predictive value (NPV) was 72.6%. The PPV for improvement of perfusion was 84.1%, NPV was 85%, and accuracy was 84.4%. CONCLUSION: 18F-FDG imaging with Chinese PET has clinical value for assessing myocardial viability and identifying patients who will benefit from revascularization.     

核素心肌显像在冠状动脉旁路移植术中的应用

心肌存活的判断对于严重冠心病患者选择再血管化适应证、估测疗效和判断预后有着极其重要的临床意义。传统的201Tl静息-再分布显像能较好又经济地评估心肌活力,门控显像技术显示的室壁运动情况能帮助医师更准确地判断缺血心肌的活力,18F-氟代脱氧葡萄糖(18F-FDG)心肌代谢显像是迄今评估心肌活力最准确的方法。患者在冠状动脉旁路移植术后出现胸闷症状时,核素心肌显像也能准确地判断有无新发缺血灶或是原有病变术后再狭窄。     

核素显像识别存活心肌的临床应用进展

存活心肌的判断对冠心病患者治疗方案的选择及预后十分重要。201Tl再注射法、硝酸甘油介入的静息99Tcm-sestamibi法增强了心肌灌注核素体层显像对存活心肌的检测能力,门控SPECT技术能在评估心肌灌注的同时计算LVEF(左心室射血分数)、局部室壁运动和局部室壁增厚率,具有符合线路的SPECT可以进行心肌代谢显像及灌注显像,其对存活心肌的检测能力可能接近于PET,而检查费用可大大降低。     

Nitrate-augmented myocardial imaging for assessment of myocardial viability

²⁰¹Tl myocardial perfusion imaging is presently done by several possible strategies. Stress/delayed redistribution, stress/redistribution/reinjection, and rest/redistribution imaging can be useful in the clinical assessment of myocardial viability. Unfortunately, the extent of myocardial viability may still be underestimated even by ²⁰¹Tl reinjection imaging, compared with ¹⁸F-fluorodeoxyglucose positron emission tomography. ^99mTc-labeled sestamibi imaging provides results similar to those of ²⁰¹Tl imaging in the detection of coronary artery disease, but several previous studies suggest that stress/rest ^99mTc-labeled sestamibi imaging significantly underestimates myocardial viability. Recently it has been reported that the administration of nitrates, before ²⁰¹Tl reinjection, improves detection of defect reversibility. Several studies also suggested that administration of nitrates before the injection of ^99mTc-labeled sestamibi significantly improved detection of reversibility with this agent, whereas additional studies showed further that this combination improves the predictive accuracy for recovery of left ventricular function and perfusion after coronary revascularization, compared with a standard rest ^99mTc-labeled sestamibi study. Nitrate administration before the injection of ²⁰¹Tl and ^99mTc-labeled sestamibi may thus be a potentially attractive alternative for the evaluation of myocardial viability. Although the available results are encouraging, further studies are needed to evaluate the clinical value of ²⁰¹Tl and ^99mTc-labeled sestamibi imaging, in combination with nitrates, for predicting recovery of left ventricular dysfunction.     

双核素心肌显像检测存活心肌的对比研究

目的 对比多巴酚丁胺负荷201Tl/静息99Tcm-甲氧基异丁基异腈(MIBI)双核素同步心肌断层显像及多巴酚丁胺负荷-再分布/再注射201Tl心肌断层显像法检测存活心肌的作用.方法 对160例临床怀疑有冠心病的患者予静息状态下静脉注射740 MBq99Tcm-MIBI,休息15 min后进行多巴酚丁胺负荷试验,在达到终止指标时静脉注射111 MSq201TICI.注射后观察5-lO min,分别行早期(10 min)、延迟(3 h)99Tcm-MIBI和201Tl双核素同步心肌断层显像.对早期负荷201Tl图像发现放射性缺损,延迟再分布201Tl和静息99Tcm-MIBI图像未见放射性填充的患者再注射37 MBq201TICI,30min后行再注射心肌灌注显像.负荷枷201Tl图像示放射性缺损,静息99Tcm-MIBI、再分布201Tl及再注射201Tl图像中发现任何一种放射性填充者均为存活心肌.断层显像后2周内全部患者进行了冠状动脉造影.采用SAS 6.12软件进行x2检验.结果 (1) 160例患者冠状动脉造影均发现冠状动脉狭窄.其中单支病变76例、双支病变5l例、三支病变33例.(2)152例多巴酚丁胺负荷201Tl图像发现放射性缺损的患者中,63例201Tl再分布和静息99Tcm-MIBI图像均发现放射性填充,5例201Tl再分布发现放射性填充而静息99Tcm-MIBI图像未见放射性填充,9例静息99Tcm-MIBI图像发现放射性填充而2001Tl再分布未见放射性填允,75例201Tl再分布和静息99Tcm-MIBI图像均未发现放射性填充,负荷201Tl-延迟再分布显像(66.0%,68/103)和负荷201Tl/静息99Tcm-MIBI显像(69.9%,72/103)鉴别存活心肌的灵敏度差异无统计学意义(x2=O.36,P>0.05).(3)75例201Tl再分布和静息99Tcm-MIBI图像均未发现放射性填充患者中,再注射201Tl显像后有26例放射性填充,再注射201Tl显像较单纯201Tl再分布或静息99Tcm-MIBI显像多检测出34.7%(26/75)患者有存活心肌.(4)8例多巴酚丁胺负荷201Tl、201Tl再分布图像和静息99Tcm-MIBI图像均未发现放射性稀疏,为假阴性,其中3例为三支冠状动脉病变,1例为双支冠状动脉病变(狭窄分别为90%及60%),3例为单支冠状动脉病变(狭窄<75%2例,85%1例),1例冠状动脉闭塞后有充分的侧枝循环.结论 多巴酚丁胺负荷-再分布/再注射201Tl心肌断层显像鉴别存活心肌优于多巴酚丁胺负荷201Tl/静息99Tcm-MIBI双核素同步心肌断层显像,是一种有效、无创的鉴别存活心肌的方法.     

Comparative study of single-injection, single-acquisition 99mTc-MIBI gated SPET and stress-rest perfusion SPET for the evaluation of myocardial viability after bypass surgery in coronary artery disease

In patients without previous myocardial infarction, the single-injection stress perfusion/rest function (SISPRF) approach using stress technetium-99m methoxyisobutylisonitrile (MIBI) gated single-photon emission tomography (SPET) can substitute for conventional stress-rest myocardial perfusion imaging for the assessment of myocardial viability. This study compared pre-operative single-injection, single-acquisition ^99mTc-MIBI gated SPET and conventional stress-rest imaging for the prediction of myocardial viability in patients who underwent coronary artery bypass surgery (CABG). Rest thallium-201 SPET followed by stress ^99mTc-MIBI gated SPET was performed in 20 patients [nine with previous myocardial infarction (MI) and 11 without previous MI). The study was performed before and 3 months after CABG, and viability assessment was validated by wall motion improvement after CABG. A four-point scoring system (0-3 for normal to absent tracer uptake) for 17 segments of the left ventricular myocardium was used for the assessment of stress and rest uptake. Wall motion, wall thickening and perfusion status were analysed by semi-quantitative visual assessment. On gated SPET, perfusion defect reversibility was considered present when a definite perfusion defect was observed and wall motion or thickening was normal or showed only a mild decrease. In patients with a previous MI, the left ventricular ejection fraction improved significantly after CABG (46%lj% vs 42%ᆟ% before CABG, P<0.05). In patients without previous MI, the ejection fraction improved significantly after CABG (50ᆠ% vs 44%ᆤ% before CABG, P<0.05). In patients with previous MI, positive predictive values using the stress-rest reversibility and SISPRF approaches were 91% and 90%, respectively, and corresponding negative predictive values were 25% and 18%. In patients without previous MI, positive predictive values using the stress-rest and SISPRF approaches were 70% and 61%, respectively, and corresponding negative predictive values were 63% and 14%. It is concluded that SISPRF SPET study is of similar value to conventional stress-rest perfusion study in predicting wall motion improvement in patients with a previous MI, but that it is of limited value in predicting the myocardial viability of patients without previous MI, owing to a lower predictive value.