Effect of collateral circulation on myocardial protection in patients with acute myocardial infarction: comparison of technetium-99m-tetrofosmin myocardial single photon emission computed tomography and coronary angiography

OBJECTIVES: Evaluation of myocardial blood flow from collateral vessels into the infarct area has been estimated by coronary angiography. In patients with acute myocardial infarction with Thrombolysis in Myocardial Infarction (TIMI) 0 flow, myocardial tracer uptake on single photon emission computed tomography (SPECT) images can predict the collateral blood flow in the infarct area if technetium (Tc)-99m-tetrofosmin was administered before recanalization. The present study investigated whether collateral blood flow evaluated by myocardial scintigraphy is a good predictor of myocardial salvage in patients with acute myocardial infarction. METHODS: The study group consisted of 30 patients (mean age 65 +/- 14 years, 23 males, 7 females) with first acute myocardial infarction and coronary angiography evidence of total occlusion (TIMI 0) within 12 hr after the onset. All patients had one vessel disease related to infarction and TIMI 3 flow after percutaneous coronary intervention (PCI). Tc-99m-tetrofosmin was injected intravenously before the PCI. The regional severity score index (RSSI) was obtained from SPECT using the 17 segment method with the four-point scoring system. Myocardial viability was evaluated by the RSSI obtained from thallium-glucose-insulin infusion SPECT after 1 week and regional wall motion score index obtained from echocardiography during the chronic phase. RESULTS: The patients were divided into two groups according to the angiographic collateral finding. There were no differences in RSSI on thallium-glucose-insulin SPECT and regional wall motion score between the good collateral group (n = 8) and poor collateral group (n = 22). Myocardial Tc-99m-tetrofosmin RSSI was similar in these groups. On the other hand, the patients were divided according to Tc-99m-tetrofosmin scintigraphic evaluation before PCI. RSSI on thallium-glucose-insulin SPECT was significantly greater (0.7 +/- 0.5 vs 1.5 +/- 0.4, p < 0.01) and regional wall motion score was significantly less (1.46 +/- 0.50 vs 2.08 +/- 0.78, p < 0.05) in the lower Tc-99m-tetrofosmin RSSI (< 1.9) group (n = 22) compared with the higher RSSI (> or = 1.9) group (n = 8). In addition, a significant correlation was obtained between Tc-99 m-tetrofosmin RSSI and regional wall motion score index (r = 0.53, p < 0.01). CONCLUSIONS: The collateral flow evaluated by scintigraphy was significantly correlated with myocardial viability.     

Residual cardiomyocytes and scintigraphic findings in advanced coronary artery disease: correlation with technetium-99m-tetrofosmin and thallium-201 single photon emission computed tomography

A 68-year-old man suffering from chronic heart failure due to coronary artery disease (CAD) underwent rest technetium-99m (99mTc)-tetrofosmin and thallium-201 (201Tl) with reinjection studies, but died thereafter. The heart was removed and sectioned into short-axis slices and examined by gross and microscopic pathologic methods. A close correlation between the amount of residual cardiomyocytes and the level of regional tracer activity in the left ventricular wall was obtained for redistribution 201Tl, reinjection 201Tl and rest 99mTc tetrofosmin images. The correlation coefficients were r=0.901 for the 201Tl redistribution images, r=0.913 for the 201Tl reinjection images and r=0.917 for the rest 99mTc-tetrofosmin images. This case report provides further evidence of the validity of SPECT tetrofosmin imaging for the determination of myocardial viability in CAD.     

Myocardial technetium-99m-tetrofosmin single-photon emission computed tomography compared with 18F-fluorodeoxyglucose imaging to assess myocardial viability

Technetium-99m-tetrofosmin single-photon emission computed tomography at rest is practical for routine assessment of viability in patients with ischemic cardiomyopathy. However, underestimation of viability may occur compared with 18F-fluorodeoxyglucose single-photon emission computed tomography, especially in the inferoposterior and septal regions.     

Relationship between lung-to-heart uptake ratio of technetium-99m-tetrofosmin during exercise myocardial single photon emission computed tomographic imaging and the number of diseased coronary arteries in patients with effort angina pectoris without myocardial infarction

OBJECTIVES: Increased lung uptake of thallium-201 in exercise myocardial perfusion imaging is a reliable marker of multivessel disease in patients with ischemic heart disease. This study investigated whether the lung-to-heart uptake ratio with techenetium-99m(99mTc)-tetrofosmin also provides valuable information to detect patients with multivessel disease. METHODS: Fifty-three consecutive patients (35 men, 18 women, mean age 66 +/- 11 years; single-vessel disease: 29, double-vessel disease: 16, triple-vessel disease: 8) with stable effort angina pectoris without prior myocardial infarction and 17 control subjects (12 men, 5 women, mean age 62 +/- 9 years) underwent exercise myocardial perfusion imaging with 99mTc-tetrofosmin and coronary angiography in January 2000 to December 2002. The lung-to-heart uptake ratio was calculated on an anterior projection before reconstruction of the exercise single photon emission computed tomographic images. RESULTS: The mean lung-to-heart uptake ratio was 0.34 +/- 0.04, 0.38 +/- 0.07, 0.41 +/- 0.05, and 0.46 +/- 0.09, in patients with normal coronary, single-vessel disease, double-vessel disease, and triple-vessel disease, respectively. Significantly higher lung-to-heart uptake ratio was associated with more diseased vessels (p < 0.05). Multivessel disease could be detected with a sensitivity of 67% and a specificity of 74% if the cut-off point of the lung-to-heart uptake ratio was set as 0.4. Combining lung-to-heart uptake ratio with conventional myocardial perfusion imaging improved the sensitivity to detect multivessel disease to 83% and the specificity to 74%. CONCLUSIONS: Lung-to-heart uptake ratio measured by exercise myocardial scintigraphy with 99mTc-tetrofosmin can provide clinically useful information to detect multivessel disease in patients with ischemic heart disease.     

Usefulness of technetium-99m methoxyisobutylisonitrile liver single photon emission computed tomography to detect hepatocellular carcinoma

Technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) has been shown to be useful in identifying several types of tumors, such as breast, lung and thyroid cancers. The usefulness of Tc-99m MIBI liver imaging in detecting hepatocellular carcinoma (HCC) is still controversial. In this study, 22 patients with HCC performed Tc-99m MIBI liver single photon emission computed tomography (SPECT). Twenty of 22 patients (90.9%) showed negative liver SPECT findings without significant Tc-99m MIBI uptake in HCC, and only 2 patients (9.1%) showed positive liver SPECT findings with significant Tc-99m MIBI uptake in HCC. In addition, no significant correlation between liver SPECT findings with sex, age, alpha feto-protein serum level, HCC differentiation, and virus hepatitis status was found. We concluded that Tc-99m MIBI liver SPECT is not a sensitive tool to detect HCC.     

Assessment of left ventricular function by electrocardiogram-gated myocardial single photon emission computed tomography using quantitative gated single photon emission computed tomography software]

Electrocardiogram (ECG)-gated myocardial single photon emission computed tomography (SPECT) can assess left ventricular (LV) perfusion and function easily using quantitative gated SPECT (QGS) software. ECG-gated SPECT was performed in 44 patients with coronary artery disease under post-stress and resting conditions to assess the values of LV functional parameters, by comparison to LV ejection fraction derived from gated blood pool scan and myocardial characteristics. A good correlation was obtained between ejection fraction using QGS and that using cardiac blood pool scan (r = 0.812). Some patients with myocardial ischemia had lower ejection fraction under post-stress compared to resting conditions, indicating post-stress LV dysfunction. LV wall motion and wall thickening were significantly impaired in ischemic and infarcted myocardium, and the degree of abnormality in the infarcted areas was greater than in the ischemic area. LV functional parameters derived using QGS were useful to assess post-stress LV dysfunction and myocardial viability. In conclusion, ECG-gated myocardial SPECT permits simultaneous quantitative assessment of myocardial perfusion and function.     

Dipyridamole myocardial perfusion single photon emission computed tomography in patients with slow coronary flow

OBJECTIVE: Several studies have indicated that the velocity of contrast dye increases after intravenous dipyridamole infusion in patients with a slow-flow pattern (SFP). In this study we compared the results of coronary arteriography and exercise myocardial perfusion single photon emission computed tomography (SPECT) in patients with SFP. We also investigated the changes in myocardial perfusion in patients with abnormal exercise myocardial perfusion SPECT by using a pharmacological stress test with dipyridamole. DESIGN AND PATIENTS: This study included 60 patients who revealed SFP in their coronary arteriograms. Slow coronary flow diagnoses were made using the frame count method. A single day rest-exercise technetium-99m hexakis-2-methoxy-isobutyl isonitrile (Tc-99m MIBI; Du Pont Pharma SA, Belgium) SPECT was performed in all patients. Patients who had reversible perfusion defect (RPD) on the exercise SPECT were evaluated with dipyridamole myocardial perfusion scintigraphy.RESULTS Patients with SFP revealed both higher frame counts in native coronary arteries and higher mean frame counts. The coronary frame count was 26.4 +/- 3.5 in control patients and 64.40 +/- 16.64 in patients with SFP, respectively (P < 0.001). Exercise perfusion SPECT showed RPD in 17 patients (group 1), but was normal in 43 others (group 2). There were no statistically significant differences between groups 1 and 2 in frame counts. Myocardial perfusion was normalized in all 17 patients of group 1 after dipyridamole infusion. CONCLUSIONS: In patients with SFP perfusion, changes may improve with dipyridamole infusion. This study indicates that this improvement can be shown by dipyridamole SPECT. Furthermore, no correlation was observed between the time needed to fill a native coronary artery and RPD of the myocardium.     

Correlation of abnormal response of left ventricular ejection fraction after exercise and left ventricular cavity-to-myocardium count ratio of technetium-99m-tetrofosmin single photon emission computed tomography in patients with coronary artery disease

The aim of this study was to assess the value of the left ventricular cavity-to-myocardium count ratio (C/M ratio) of technetium-99m (Tc-99m) tetrofosmin single photon emission computed tomography (SPECT) to identify abnormal left ventricular ejection fraction (LVEF) responses after exercise in patients with coronary artery diseases (CAD). We studied 50 patients with recent CAD undergoing rest and exercise first-pass ventriculography to calculate LVEF and rest and exercise Tc-99m tetrofosmin myocardial perfusion SPECT to calculate left ventricular C/M ratios. Group A, consisting of 25 CAD patients with normal responses (increased LVEF> or =5% after exercise), had significantly higher rest and exercise C/M ratios than those of the group B, consisting of 25 CAD patients with abnormal responses (increased LVEF <5% after exercise) after exercise. However, the C/M ratios between exercise and rest did not differ significantly between groups A and B. In addition, there was significant correlation between LVEF and C/M ratios in all of the patients. C/M ratios of Tc-99m tetrofosmin myocardial perfusion SPECT are useful parameters for identifying patients with abnormal LVEF responses among patients with CAD.     

冠状动脉介入治疗前后腺苷负荷心肌核素显像的临床意义

目的探讨腺苷负荷心肌核素显像对于冠状动脉介入治疗的临床意义。方法冠心病可疑患者住院,行腺苷负荷心肌核素显像和冠状动脉造影,根据需要进行介入治疗,介入治疗后3~7天复查腺苷负荷心肌核素显像。腺苷负荷心肌核素显像采用单光子发射断层显像图像采集系统,腺苷总量为840ΜG/KG,6分钟匀速静脉泵入,腺苷泵入3分钟时静脉推注99MTC-MIBI925MBQ,1·5小时后进行心肌断层显像。若异常,次日行静息心肌显像。核素显像左室心肌分为17个节段,心肌灌注分4级。结果63例冠心病患者,平均(63±10)岁,40例得到介入处理,其中28例患者冠状动脉介入处理后复查腺苷负荷心肌核素显像,介入后心肌核素血流灌注较介入前明显改善(P<0·01)。结论腺苷负荷心肌核素显像对于冠心病患者冠状动脉介入前病变分析以及介入后疗效判断有一定的临床意义。     

New method of estimating myocardial infarct size using technetium-99m pyrophosphate and thallium-201 dual single photon emission computed tomography imaging

A new method was devised to estimate infarct size using dual single photon emission computed tomography with thallium-201 and technetium-99m pyrophosphate. Designating the ratio of infarct area to whole myocardial volume as %MI, the correlation of %MI with other markers of left ventricular dysfunction was examined: peak creatine kinase, ejection fraction and left ventricular asynergy. As %MI correlated well with these markers, it is considered that %MI will be useful for estimating infarct size and predicting the severity of left ventricular dysfunction in the early stage of acute myocardial infarction.     

药物负荷试验核素心肌断层显像识别存活心肌

目的探讨药物多巴酚丁胺、硝酸异山梨酯负荷试验核素锝[^99mTc]甲氧异丁异腈（technetium [^99mTc] methoxy isobutyl isonitrile,^99mTc-MIBI）心肌断层显像识别存活心肌的价值。方法对48例陈旧性心肌梗死伴左心室收缩功能受损患者进行静息心肌^99mTc-MIBI心肌断层显像和多巴酚丁胺、硝酸异山梨酯负荷试验^99mTc-MIBI心肌断层显像,用半定量的方法将^99mTc-MIBI摄取进行评分,区分存活心肌和非存活心肌。结果^99mTc-MIBI显像判定,经皮冠状动脉介入术前存活心肌节段有279个．非存活心肌节段235个;经多巴酚丁胺加硝酸异山梨酯负荷后,心肌显像改善：轻度稀疏节段9个、中度稀疏节段24个、严重稀疏或缺损节段10个,共计43个节段显像改善,评分减少1分以上,存活心肌节段313个,非存活心肌节段201个。两组差异有统计学意义（P〈0．05）。经皮冠状动脉介入术后6个月,随访多巴酚丁胺加硝酸异山梨酯负荷后,心肌显像改善的32个节段发现,静息^99mTc-MIBI显像改善,另有8个受损节段正常化。多巴酚丁胺加硝酸异山梨酯负荷后心肌显像无变化的389个节段在经皮冠状动脉介入术后346个节段无变化。多巴酚丁胺加硝酸异山梨酯负荷心肌显像检测存活心肌的阳性预测值93％,阴性预测值89％。结论多巴酚丁胺加硝酸异山梨酯负荷后心肌显像对存活心肌的识别能够提高存活心肌的检出率。其阳性预测值和阴性预测值较好。     

Detection of a biphasic response of hibernating myocardium by dobutamine-stress electrocardiography-gated technetium-99m-tetrofosmin single photon emission computed tomography--a case report.

A woman with coronary artery disease underwent a new imaging technique: dobutamine-stress electrocardiography (ECG)-gated tetrofosmin-single photon emission computed tomography (SPECT). Dobutamine-stress ECG-gated tetrofosmin-SPECT with automatic left ventricular function analysis software programs detected improvement and a biphasic response of dysfunctional myocardium during dobutamine infusion, which suggested viable but hibernating myocardium. Dobutamine-stress ECG-gated tetrofosmin-SPECT with automatic left ventricular function analysis software programs has the potential to detect viable but dysfunctional myocardium with contractile reserve.     

Feasibility of assessing regional myocardial uptake of 18F-fluorodeoxyglucose using single photon emission computed tomography

Differentiation between viable myocardium and scar tissue insegments with abnormal contraction has important consequencesin the clinical management of patients with coronary arterydisease. Positron emission tomography (PET) can identify viabletissue using ¹⁸F-fluorodeoxyglucose (FDG). However, applicationof PET for daily routine is limited. In this study, FDG uptakewas visualized with single photon emission computed tomography(SPECT) and compared with regional perfusion assessed with thallium-201(²⁰¹Tl) SPECT. The scintigraphic findings were related to regionalregional wall motion determined with two-dimensional echocardiography.Patients (n = 9) with wall motion abnormalities underwent FDGSPECT and resting ²⁰¹Tl SPECT. To control the metabolic statuspatients were studied with a hyperinsulinaemic euglycemic clampduring FDG SPECT. Analysis of reconstructed data was performedvisually and semiquantitatively using circumferential profiles.High-quality images were obtained. Eight ²⁰¹Tl defects showedconcordantly decreased FDG uptake (metabolism-perfusion matches)indicating scarred tissue, whereas six regions of hypoperfusiondemonstrated a relatively increased FDG uptake (mismatches),suggesting viable myocardium. Semiquantitative analysis confirmedvisual findings. Mean ²⁰¹Tl and FDG activities were not significantlydifferent in matching defects. In mismatches the mean FDG activitywas 81 ± 11% vs 64 ± 9% mean ²⁰¹Tl activity (P<0.0001).In four of six segments with increased FDG uptake, two-dimensionalecho revealed hypokinesia. Seven of eight regions with a matchingdefect in contrast were akinetic. Thus, in the areas with amismatch contractility was preserved. We conclude that FDG uptakecan be visualized with SPECT. Furthermore, our preliminary observationssuggest that this approach can identify viable tissue.     

Single photon emission computed tomography of technetium-99m tetrofosmin myocardial perfusion imaging in patients with systemic lupus erythematosus--a preliminary report

The purpose of this study was to evaluate the utility of single-photon emission computed tomography (SPECT) of technetium-99m tetrofosmin (Tc-99m TF) myocardial perfusion imaging to detect myocardial involvement in patients with systemic lupus erythematosus (SLE). Three groups of subjects-group 1: 25 SLE female patients with non-specific cardiac symptoms and signs, group 2: 25 female SLE patients without any cardiac symptoms and signs, and group 3: 25 female healthy controls-were evaluated by comparing rest and dipyridamole-stress Tc-99m TF myocardial perfusion SPECT. Tc-99m TF myocardial perfusion SPECT revealed perfusion defects in 88% and 40% of the cases in groups 1 and 2. respectively. However, no cases in group 3 demonstrated myocardial perfusion defects. Tc-99m TF myocardial perfusion SPECT is a useful noninvasive imaging modality to detect cardiac involvement in SLE patients with or without cardiac symptoms and signs.     

Technetium-99m tetrofosmin myocardial perfusion single photon emission computed tomography in syndrome X: a preliminary report

Syndrome X is used to describe patients with chest pain and a normal coronary angiogram. We reviewed technetium-99m tetrofosmin (Tc-99m TF) myocardial perfusion single photon emission computed tomography (SPECT) results and clinical data of 43 syndrome X patients and 30 healthy controls with normal left ventricular ejection fraction and no cardiac abnormalities. The Tc-99m TF myocardial perfusion SPECT results showed 12 (27.9%) syndrome X patients had normal myocardial perfusion and 31 (72.1%) had abnormal myocardial perfusion, including 6 (14.0%) patients with fixed defects. 20 (46.5%) patients with transient defects, and 5 (11.6%) patients with reverse defects. The results of exercise ECG were not related to perfusion defects in Tc-99m TF myocardial perfusion SPECT. In contrast, all of the 30 (100.0%) healthy controls had normal myocardial perfusion SPECT results. We conclude that abnormal Tc-99m TF myocardial perfusion SPECT is common in syndrome X and does not correlate well with the exercise ECG. However, further studies with larger case numbers and long term follow up in patients with myocardial events are necessary to support our findings.     

Measurement of myocardial infarction fraction using single photon emission computed tomography

Although infarct size correlates generally with prognosis after acute myocardial infarction, an absolute measure of infarct size may have differing prognostic significance depending on absolute left ventricular mass. To test the hypothesis that single photon emission computed tomography can accurately measure myocardial infarct size as a percent of total left ventricular mass ("infarction fraction"), thallium-201 and technetium-99m pyrophosphate tomograms were acquired in 21 dogs 24 to 48 hours after fixed occlusion of the left anterior descending or circumflex coronary artery. Pathologic infarct weight was measured as the myocardial mass that showed no staining with triphenyltetrazolium chloride. Scintigraphic infarct mass by technetium-99m pyrophosphate was calculated from the total number of left ventricular volume elements (voxels) demonstrating technetium-99m pyrophosphate uptake X voxel dimension [( 0.476 cm]3) X specific gravity of myocardium (1.05 g/cm3). Scintigraphic left ventricular mass was calculated in a similar fashion using an overlay of the thallium-201 and technetium-99m pyrophosphate scans. The "infarction fraction" was calculated as: infarction fraction = infarct mass/left ventricular mass. There was good correlation between single photon emission computed tomography and pathologic measurements of infarct mass (technetium-99m pyrophosphate mass = 1.01 X pathologic infarct mass + 0.96; r = 0.98), left ventricular mass (single photon emission computed tomographic left ventricular mass = 0.60 X pathologic left ventricular mass + 37.4; r = 0.86) and "infarction fraction" (single photon emission computed tomographic infarction fraction = 1.09 X pathologic infarction fraction - 1.7; r = 0.94).(ABSTRACT TRUNCATED AT 250 WORDS)     

心肌桥患者~(99)Tc~m-MIBI运动负荷心肌血流灌注断层显像的特点

目的 总结和分析冠状动脉心肌桥患者99Tcm-MIBI运动负荷心肌血流灌注断层显像的特点.方法 回顾2003年至2009年经冠状动脉造影证实的冠状动脉心肌桥患者17例,分析其~(99)Tc~m-MIBI运动负荷心肌血流灌注断层显像放射性分布特点.结果 17例心肌桥患者中有12例患者出现异常心肌血流灌注断层影像.6例收缩期壁冠状动脉受压狭窄＜50%的患者中有2例患者出现异常心肌血流灌注断层影像,表现为可逆性缺损和反向再分布.4例收缩期壁冠状动脉受压狭窄50%～75%的患者中有3例患者出现异常心肌血流灌注断层影像,表现为可逆性缺损、部分可逆性缺损、固定缺损、反向再分布.7例收缩期壁冠状动脉受压狭窄75%～100%的患者心肌血流灌注断层影像异常率为100%,表现为可逆性缺损、部分可逆性缺损、固定缺损、反向再分布.结论 冠状动脉心肌桥患者可以导致心肌血流灌注断层显像异常.收缩期壁冠状动脉受压75%～100%心肌桥患者均出现异常心肌血流灌注断层显像.     

Reverse redistribution of technetium-99m-tetrofosmin after acute coronary revascularization in patients with myocardial infarction

This study qualified the severity and localization of reverse redistribution of technetium-99 m (Tc)-tetrofosmin rest imaging. Both Tc-tetrofosmin and thallium-201 (Tl) rest imaging with early images and delayed images were obtained in the subacute phase of myocardial infarction in 21 patients with first anterior myocardial infarction and with successful transluminal angioplasty (including stenting). Relative myocardial uptake (%uptake), degree of reverse redistribution (%), and washout rate (%) were evaluated quantitatively in 6 left ventricular segments (inferoseptal, anteroseptal, anterior, anterolateral, lateral, inferolateral and inferior) by circumferential profile analysis. The percentage reverse redistribution in the infarct area was larger in Tc-tetrofosmin imaging than in Tl imaging (p = 0.013). Reverse redistribution was most prominent in the anterior wall (anterior > anteroseptal > inferoseptal, p = 0.020). This suggests that infradiaphragmatic scatter is unlikely as the mechanism of reverse redistribution. The washout rate of Tc-tetrofosmin in the infarct area (reverse redistribution area) was higher than that in the normal area (non-reverse redistribution area), and was also higher than the washout rate of Tl imaging in the infarct area. The %uptake of delayed images in the infarct area was larger in Tc-tetrofosmin than that in Tl imaging, whereas %uptake of early images did not differ. The percentage reverse redistribution did not correlate with the degree of collateral circulation and the residual stenosis. In conclusion, reverse redistribution of Tc-tetrofosmin was more prominent in the infarct area, and this was due to the relatively lower uptake of reverse redistribution of Tc-tetrofosmin than delayed Tl images.