Estimation of coronary flow reserve by Tc-99m sestamibi imaging in patients with coronary artery disease: Comparison with the results of intracoronary Doppler technique

BACKGROUND: This study compared coronary flow reserve (CFR) estimated by technetium 99m sestamibi imaging with the results obtained with intracoronary Doppler in patients with coronary artery disease. Intraobserver and interobserver reproducibility of the radionuclide-estimated CFR was also assessed. METHODS AND RESULTS: Fourteen consecutive patients (mean age, 54 +/- 7 years) with documented coronary artery disease in whom percutaneous coronary intervention was planned underwent dipyridamole (0.74 mg/kg) sestamibi imaging and intracoronary Doppler within 5 days. Myocardial blood flow (MBF) was estimated by measurement of first transit counts in the pulmonary artery and myocardial counts from single photon emission computed tomography images. Estimated CFR was expressed as the ratio of stress MBF to rest MBF. In the study vessels, CFR was 1.36 +/- 0.43 as estimated by sestamibi and 1.39 +/- 0.42 by intracoronary Doppler ( P = .69). A significant relationship between CFR estimated by sestamibi and CFR obtained by intracoronary Doppler was observed ( r = 0.85, P < .001). On Bland-Altman analysis, the mean difference between CFR by sestamibi and by Doppler was 0.03 and the intraclass correlation coefficients for intraobserver and interobserver reproducibility were high (all P < .001) for both global and regional CFR. CONCLUSIONS: This study demonstrates a good agreement between CFR estimated by sestamibi imaging and by intracoronary Doppler results and a lack of intraobserver and interobserver variability of this noninvasive approach.     

PET心肌灌注显像测定心肌血流量及冠状动脉血流储备的研究进展

PET心肌灌注显像可绝对定量测定局部心肌血流量（MBF）和冠状动脉血流储备（CFR）。由于显像剂半衰期短,允许在短时间内重复进行PET心肌灌注显像,获得静息态、冷加压试验和药物负荷试验等不同状态下的MBF,进而评价冠状动脉血管内皮依赖性和非依赖性的CFR功能。在早期诊断冠心病,准确诊断冠状动脉多支病变,评价微血管病变,早期检测冠状动脉内皮细胞功能异常及CFR功能的异常,估测预后,帮助临床治疗方案的制定以及检测疗效等方面,PET心肌灌注显像有重要的临床价值。该文将介绍PET心肌灌注显像相关知识及其在心血管领域的主要应用。     

Myocardial flow reserve is influenced by both coronary artery stenosis severity and coronary risk factors in patients with suspected coronary artery disease

Purpose Myocardial flow reserve (MFR) measurement has an important role in assessing the functional severity of coronary artery stenosis. However, a discrepancy between the anatomical severity of coronary artery stenosis and MFR is often observed. Such a discrepancy may be explained by coronary risk factors. In this study, we aimed to investigate the influence of coronary artery stenosis severity and risk factors on MFR.Methods Seventy-four patients suspected to have coronary artery disease and seven age-matched healthy volunteers were enrolled. Myocardial blood flow (MBF) and MFR were measured using ¹⁵O-labelled water PET. Regional MFR was calculated in regions with significant coronary artery stenosis (stenotic regions) and in regions without significant stenosis (remote regions). The contributions of coronary artery stenosis severity and coronary risk factors were assessed using univariate and multivariate analyses.Results In stenotic regions, MFR correlated inversely with coronary artery stenosis severity (r=−0.50, p<0.01). Univariate analysis did not show any significant difference in MFR between the patients with and the patients without each risk factor. In remote regions, however, MFR was significantly decreased in the diabetes and smoking groups (each p<0.05). By multivariate analysis, diabetes and smoking were independent predictors of MFR (each p<0.05). In the group with more than one risk factor, MFR was significantly lower (2.78±0.79) than in the other group (3.40±1.22, p<0.05).Conclusion MFR is influenced not only by coronary stenosis severity but also by coronary risk factors. In particular, the influence of risk factors should be considered in regions without severe coronary stenosis.This study received no financial sponsorship.     

Reversible impairment of coronary flow reserve in takotsubo cardiomyopathy: A myocardial PET study

Background. The precise etiology of takotsubo cardiomyopathy remains unclear. The study of myocardial blood flow (MBF) and coronary flow reserve (CFR) by use of positron emission tomography might help in understanding this syndrome. Methods and Results. Three postmenopausal women underwent adenosine/rest perfusion with nitrogen 13 ammonia and metabolism with fluorine 18 fluorodeoxyglucose positron emission tomography, coronary angiography, cardiac magnetic resonance, and echocardiography in the acute phase of takotsubo cardiomyopathy and at 3 months’ follow-up, after normalization of left ventricular function. PET study was performed in 2 parts: the perfusion analysis with nitrogen ammonia and the metabolism of the heart using FDG. MBF and CFR were analyzed quantitatively in the acute phase and at follow-up. The images highlighted the impairment of tissue metabolism in the dysfunctioning left ventricular segments in the acute phase, mainly in the apical segments and progressively less in the medium segments. At the same time, a clear inverse metabolic/perfusion mismatch emerged, which normalized 3 months later. The quantitative analysis of MBF showed a reduction in the acute phase in apical segments in comparison to basal segments without differences between midventricular and basal segments. In the acute phase CFR proved to be reduced in apical versus basal segments. CFR impairment of apical segments recovered completely after 3 months. Conclusion. The acute phase of takotsubo cardiomyopathy is characterized by an inverse perfusion/metabolism mismatch with a reduction in CFR in the apical segments. However, the impairment of CFR and the reduction of metabolism in the apical segments recovered completely after 3 months.     

Comparison of Tc-99m sestamibi SPECT with fractional flow reserve in patients with intermediate coronary artery stenoses

BACKGROUND: Myocardial single photon emission computed tomography (SPECT) is an established noninvasive method for the assessment of the functional significance of coronary artery stenoses. Intracoronary pressure measurements to determine fractional flow reserve (FFR) are increasingly performed during coronary angiography whenever an immediate decision regarding possible intervention is required. We hypothesized that the regional summed difference score (SDSr), reflecting reversible perfusion defects in the myocardial supply area of the FFR target vessel, would be the best predictor of an abnormal FFR in patients without prior myocardial infarction. Otherwise, a regional summed stress score (SSSr) should be the best predictor of an abnormal FFR in patients with prior myocardial infarction for different patient subgroups with coronary artery disease. METHODS AND RESULTS: In this study 50 patients (mean age, 65 +/- 9.1 years; 18 women) with coronary artery disease and a 50% to 75% coronary stenosis (target vessel) were prospectively investigated. Dobutamine myocardial SPECT was performed as a single-day stress/rest protocol by use of technetium 99m sestamibi. For image interpretation, semiquantitative analysis was conducted by calculating SSSr and SDSr. Within 8 (+/-14.9) days, coronary angiography was performed and FFR was calculated by use of a pressure wire (normal FFR, > or = 0.75). The mean FFR of all patients was 0.78 +/- 0.14. Of 50 patients, 17 had an FFR lower than 0.75 in the target vessel. Receiver operating characteristic analysis identified an SDSr of 1 or greater and an SSSr of 3 or greater as the best threshold values for predicting ischemic FFR. Sensitivity, specificity, and negative and positive predictive values of SDSr and SSSr for the detection of FFR values lower than 0.75 in the target vessel were 80%, 76%, 53%, and 92%, respectively, and 70%, 93%, 78%, and 90%, respectively, in patients without prior myocardial infarction and 57%, 50%, 67%, and 40%, respectively, and 100%, 50%, 78%, and 100%, respectively, in patients with prior myocardial infarction. Weak correlation was found between the single values of FFR with both SDSr and SSSr for the different patient subgroups. CONCLUSION: Among the dobutamine myocardial scintigraphy variables studied, SDSr was the best predictor of an abnormal FFR (cutoff value of 0.75) in patients without prior myocardial infarction. As assumed, SSSr was the best predictor of an abnormal FFR in patients with prior myocardial infarction in the target region.     

Relationship between CT coronary angiography and stress perfusion imaging in patients with suspected ischemic heart disease assessed by integrated PET-CT imaging

Background Although computed tomography (CT) coronary angiography (CTA) provides detailed assessments of the anatomic extent of coronary artery disease (CAD), its value for predicting myocardial ischemia is unclear. We examined the value of CTA to identify the presence of ischemia, as determined by stress perfusion imaging, using integrated positron emission tomography (PET)-CT imaging. Methods and Results We studied 110 consecutive patients (median age, 57 years; 55% male) with suspected CAD undergoing stress rubidium 82 myocardial perfusion PET imaging and CTA in the same setting. Increasing degrees of CTA-detected luminal narrowing (<50%, 50%–70%, and >70%) were associated with reduced sensitivity with commensurate improvements in specificity for identifying myocardial ischemia both on a per-vessel basis and on a per-patient basis. Consequently, with increasing degrees of CTA-detected stenosis severity, the positive predictive value increased (14%, 26%, and 53%, respectively, on a per-vessel basis [P<.001] and 29%, 44%, and 77%, respectively, on a per-patient basis [P=.005]), whereas the negative predictive value was unchanged (97%, 97%, and 96%, respectively, on a per-vessel basis [P=not significant (NS)] and 92%, 91%, and 88%, respectively, on a per-patient basis [P=NS]). Receiver operating characteristic analysis revealed no differences between these 3 anatomic criteria (receiver operating characteristic areas of 0.66±0., 0.73±0.06, and 0.71±0., respectively [P=NS]) for identifying ischemia. Nearly half of significant angiographic stenoses (47%) occurred without evidence of myocardial ischemia, whereas 50% of normal PET studies were associated with some CTA abnormality. Conclusions Despite an excellent negative predictive value, CTA is a poor discriminator of patients with myocardial ischemia. Conversely, a normal stress PET study is a poor discriminator of patients without evidence of non—flow-limiting (subclinical) coronary atherosclerosis. These results suggest potentially complementary roles of CT and perfusion imaging in the evaluation of patients with suspected CAD.     

Underestimation of extent of ischemia by gated SPECT myocardial perfusion imaging in patients with left main coronary artery disease

Background  There have been limited data regarding the value of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the detection of left main coronary artery disease (CAD). Methods and Results  We studied 101 patients with angiographic left main CAD (≥50% stenosis) and no prior myocardial infarction or coronary revascularization who underwent gated exercise or adenosine stress technetium 99m sestamibi SPECT MPI. By perfusion assessment alone, high-risk disease with moderate to severe defects (>10% myocardium at stress) was identified in only 56% of patients visually and 59% quantitatively. Absence of significant perfusion defect (≥5% myocardium) was seen in 13% of patients visually and 15% quantitatively. However, by combining visual perfusion data and nonperfusion variables, especially transient ischemic dilation, 83% of patients were identified as high risk. Conclusions  The findings of this study demonstrate that assessment of perfusion data alone by visual or quantitative SPECT MPI analysis underestimates the magnitude of left main CAD. The combination of perfusion and nonperfusion abnormalities on gated MPI identifies high risk in most patients with left main CAD. This study was presented in part at the American College of Cardiology 56th Annual Scientific Session, March 24–27, 2007, New Orleans, La. This work was supported in part by grants from Bristol-Myers Squibb Medical Imaging, Billerica, Mass, and Astellas, Deerfield, Ill.     

SPECT myocardial perfusion versus fractional flow reserve for evaluation of functional ischemia: A meta analysis

Purpose

The present meta-analysis illustrates the accuracy of myocardial perfusion SPECT (MPS) to diagnose functional stenotic coronary artery disease (CAD) with fractional flow reserve (FFR) as standard reference.

Methods

All investigators screened and selected studies that compared MPS with FFR in symptomatic patients with suspected CAD. Patients and study characteristics were independently extracted by two investigators; differences were resolved by consensus.

Results

13 articles, including 1,017 patients, 699 vessels were included in the study. No significant publication bias was detected (P = 0.65). At the patient level, the summary sensitivity and specificity were 77% (95% confidence interval [CI], 70–83%) and 77% (95%CI, 67–84%) for MPS. Vessel-level pooled sensitivity was 66% (95%CI, 57–74%) and specificity was 81% (95%CI, 70–89%). The overall diagnostic performance of MPS was moderate. [The area under the summary receiver operating characteristic (sROC) curve was 0.83]. No study influenced the pooled results larger than 0.03.

Conclusions

The accuracy between FFR and MPS SPECT was moderate.     

Physiologic evaluation of ischemia using cardiac CT: Current status of CT myocardial perfusion and CT fractional flow reserve

Cardiac CT, specifically coronary CT angiography (CTA), is an established technology which detects anatomically significant coronary artery disease with a high sensitivity and negative predictive value compared with invasive coronary angiography. However, the limited ability of CTA to determine the physiologic significance of intermediate coronary stenoses remains a shortcoming compared with other noninvasive methods such as single-photon emission CT, stress echocardiography, and stress cardiac magnetic resonance. Two methods have been investigated recently: (1) myocardial CT perfusion and (2) fractional flow reserve (FFR) computed from CT (FFRCT). Improving diagnostic accuracy by combining the anatomic aspects of coronary CTA with a physiologic assessment via CT perfusion or FFRCT may reduce the need for additional testing to evaluate for ischemia, reduce downstream costs and risks associated with an invasive procedure, and lead to improved patient outcomes. Given a rapidly expanding body of research in this field, this comparative review summarizes the present literature while contrasting the benefits, limitations, and future directions in myocardial CT perfusion and FFRCT imaging.     

Coronary vasodilator reserve and Framingham risk scores in subjects at risk for coronary artery disease

Background  The relationship between coronary vasodilator reserve and risk of coronary heart disease (CHD) in subjects without coronary artery disease (CAD) is not well known. Methods and Results  We studied 289 subjects (mean age, 58 ± 10 years) without overt CAD and at low (<10%) to intermediate risk (10%–20%) for CHD based on Framingham risk scores (RAMPART [Relative and Absolute Myocardial Perfusion changes as measured by Positron Emission Tomography to Assess the Effects of ACAT Inhibition: A Double-Blind, Randomized, Controlled, Multicenter Trial]). Coronary flow reserve (CFR) and coronary vascular resistance (CVR) were calculated from rest and adenosine nitrogen 13 ammonia positron emission tomography studies. Framingham-estimated CHD risk was used to as a surrogate for outcomes. Compared with subjects with low-risk scores (n = 150), those with intermediate-risk scores (n = 139) had a higher minimal CVR (49.3 ± 17.41 mm Hg · mL^-1 · min^-1 · g^-1 vs 52.4 ± 16.4 mm Hg · mL^-1 · min^-1 · g^-1, P = .05) and lower CFR (2.8 ± 1.0 vs 2.5 ± 0.8, P = .02). CFR was inversely related to CHD risk (R=-0.2, P = .006), and CVR was directly related to CHD risk (R = 0.2, P < .001). The mean CFR was significantly lower in patients in the first quartile of CHD risk compared with those in the fourth quartile (2.3 ± 0.7 vs 2.8 ± 1.0, P = .02), and the minimal CVR was significantly higher (44 ± 15 mm Hg · mL^-1 · min^-1 · g^-1 vs 53 ± 14 mm Hg · mL^-1 · min^-1 · g^-1, P < .05). Conclusions  In subjects without clinical CAD and at low to intermediate risk, CFR assessed by positron emission tomography is inversely related to estimated 10-year CHD risk.     

基于深度学习的FFRCT在可疑冠心病病人中的应用

目的 探讨基于深度学习的CT血流储备分数（FFR_CT）在可疑冠心病病人中应用的可行性,分析缺血性病变（FFR_CT≤0.80）的预测因素及对治疗决策的影响。方法 回顾性纳入因疑似冠心病行冠状动脉CT血管成像（CCTA）的病人292例,其中男187例,女105例,平均年龄（65.8±10.3）岁。利用CCTA影像将狭窄程度分为轻度 （≥25%且<50%）、中度（≥50%且<70%）和重度（≥70%且<99%）。采用基于深度学习的FFR_CT软件对病人的CCTA数据进行测量。根据FFR_CT数值范围将病人分为阳性组（FFR_CT≤0.80,102例）和阴性组（FFR_CT>0.80,190例）。2组病人的一般资料、CCTA上的血管特征及血运重建,以及基于FFR_CT与CCTA制定的治疗策略的比较采用Mann-Whitney U 检验、t检验及卡方检验。采用Logistic回归分析FFR_CT≤0.80的独立预测因素。结果 阳性组病人的年龄更大,男性更多,高血压、糖尿病和吸烟的比例均高于阴性组（均P<0.05）。阳性组较阴性组病人更多的表现为中重度狭窄（分别为80.4%和28.4%）,更多的病人行血运重建术（分别为56.8%和11.1%）,均P<0.05。74例病人（25.3%）基于FFR_CT的结果治疗决策发生改变。多因素Logsitic回归分析显示,高血压（OR=2.245）、糖尿病（OR=2.238）及中重度狭窄（OR=8.837）是FFR_CT≤0.80的独立预测因素（均P<0.05）。结论 基于深度学习的FFR_CT技术在可疑冠心病病人中的应用是可行的,高血压、糖尿病及中重度狭窄是FFR_CT≤0.80的独立预测因素,FFR_CT可能影响病人的治疗决策。     

Comparison of myocardial blood flow and coronary flow reserve during dobutamine and adenosine stress: implications for pharmacologic stress testing in coronary artery disease

BACKGROUND: Mechanistic differences between pharmacologic stressors may offer different clinical benefits. Therefore the effects of dobutamine and adenosine on absolute myocardial blood flow (MBF) and coronary flow reserve (CFR) were compared. METHODS AND RESULTS: We divided 36 patients (mean age, 61 +/- 8 years) with coronary artery disease into 2 groups based on stenosis severity as follows: greater than 50% but less than 75% (n = 16) and greater than 75% (n = 20). In addition, 18 normal volunteers (mean age, 46 +/- 7 years) served as control subjects. Groups of equal sizes received either dobutamine or adenosine. MBF at rest and peak MBF were measured by use of positron emission tomography in territories subtended by the stenosis (ischemic) and remote myocardium (remote), whereas left ventricular MBF was used in control subjects. CFR was calculated as peak MBF divided by MBF at rest. CFR was significantly greater with adenosine than with dobutamine stress in control subjects and remote CFR. Ischemic CFR was blunted to a similar degree with each stressor. Therefore adenosine achieved flow heterogeneity across all coronary stenosis severities greater than 50%. However, dobutamine achieved flow heterogeneity only in the presence of a severe coronary stenosis greater than 75% despite provoking a greater ischemic stimulus. CONCLUSION: Adenosine stress demonstrated a higher sensitivity and dobutamine demonstrated a higher specificity with quantitative perfusion imaging. Therefore adenosine is superior for diagnostic perfusion imaging, whereas dobutamine is better suited in combination with visual imaging and in the functional assessment of a known coronary stenosis.     

Quantitative assessment of myocardial perfusion with a spin-labeling technique: preliminary results in patients with coronary artery disease

PURPOSE: To determine perfusion and coronary reserve in human myocardium without contrast agent using a spin labeling technique. MATERIALS AND METHODS: Assessment of myocardial perfusion is based on T1 measurements after global and slice-selective spin preparation. This magnetic resonance imaging (MRI) technique was applied to 12 healthy volunteers and 16 patients with suspected coronary artery disease under resting conditions and adenosine-induced vasodilatation. RESULTS: In volunteers, quantitative perfusion was calculated as 2.4 +/- 1.2 mL/g/minute (rest) and 3.9 +/- 1.3 mL/g/minute (adenosine), respectively. Perfusion reserve was 2.1 +/- 0.6. In patients, when comparing perfusion reserve in the anterior and posterior myocardium, reduced values according to a stenotic supplying vessel could be seen in seven of 11 patients who underwent stress testing. In these patients, the relative difference of coronary reserve was 44% +/- 18%. Two patients without stenosis of coronary arteries showed no differences in coronary reserve (with a relative change of 2 +/- 2%). CONCLUSION: In patients with single-vessel coronary artery disease, differences in coronary reserve were clearly detectable when comparing anterior and posterior myocardium. The spin labeling method is noninvasive and easily repeatable, and it could therefore become an important tool to study changes in myocardial perfusion.     

Simultaneous assessment of myocardial perfusion and function during mental stress in patients with chronic coronary artery disease

BACKGROUND: Mental stress (MS) is an important provocateur of myocardial ischemia in many patients with chronic coronary artery disease. The majority of laboratory assessments of ischemia in response to MS have included measurements of either myocardial perfusion or function alone. We performed this study to determine the relationship between alterations in perfusion and ventricular function during MS.Methods and results Twenty-eight patients with reversible perfusion defects on exercise or pharmacologic stress myocardial perfusion imaging (MPI) underwent simultaneous technetium 99m sestamibi single photon emission computed tomography (SPECT) MPI and transthoracic echocardiography at rest and during MS according to a mental arithmetic protocol. In all cases the MS study was performed within 4 weeks of the initial exercise or pharmacologic MPI that demonstrated ischemia. SPECT studies were analyzed visually with the use of a 13-segment model and quantitatively by semiautomated circumferential profile analysis. Echocardiograms were graded on a segmental model for regional wall motion on a 4-point scale. Of 28 patients, 18 (64%) had perfusion defects and/or left ventricular dysfunction develop during MS: 9 (32%) had myocardial perfusion defects develop, 6 (21%) had regional or global left ventricular dysfunction develop, and 3 (11%) had both perfusion defects and left ventricular dysfunction develop. The overall concordance between perfusion and function criteria for ischemia during MS was only 46%. Among 9 patients with MS-induced left ventricular dysfunction, 5 had new regional wall motion abnormalities and 4 had a global decrement in function. In patients with MS-induced ischemia by SPECT, the number of reversible perfusion defects was similar during both MS and exercise/pharmacologic stress (2.8 +/- 2.0 vs 3.5 +/- 1.8, P =.41). Hemodynamic changes during MS were similar whether patients were divided on the basis of perfusion defects or left ventricular dysfunction during MS. CONCLUSIONS: These data indicate the feasibility of simultaneous assessment of perfusion and function responses during MS. Flow and function responses to MS are frequently not concordant. These data suggest that MS-induced changes in perfusion may represent a different phenomenon than MS-induced changes in left ventricular function (either globally or regionally).     

Diagnostic concordance and discordance between angiography-based quantitative flow ratio and fractional flow reserve derived from computed tomography in complex coronary artery disease

BackgroundBoth quantitative flow ratio (QFR) and fractional flow reserve derived from computed tomography (FFR_CT) have shown significant correlations with invasive wire-based fractional flow reserve. However, the correlation between QFR and FFR_CT is not fully investigated in patients with complex coronary artery disease (CAD). The aim of this study is to investigate the correlation and agreement between QFR and FFR_CT in patients with de novo three-vessel disease and/or left main CAD.MethodsThis is a post-hoc sub-analysis of the international, multicenter, and randomized SYNTAX III REVOLUTION trial, in which both invasive coronary angiography and coronary computed tomography angiography were prospectively obtained prior to the heart team discussion. QFR was performed in an independent core laboratory and compared with FFR_CT analyzed by HeartFlow?. The correlation and agreement between QFR and FFR_CT were assessed per vessel. Furthermore, independent factors of diagnostic discordance between QFR and FFR_CT were evaluated.ResultsOut of 223 patients, 40 patients were excluded from this analysis due to the unavailability of FFR_CT and/or QFR, and a total of 469 vessels (183 patients) were analyzed. There was a strong correlation between QFR and FFR_CT (R ?= ?0.759; p ?< ?0.001), and the Bland-Altman analysis demonstrated a mean difference of ?0.005 and a standard deviation of 0.116. An independent predictor of diagnostic concordance between QFR and FFR_CT was the lesion location in right coronary artery (RCA) (odds ratio 0.395; 95% confidence interval 0.174–0.894; P ?= ?0.026).ConclusionIn patients with complex CAD, QFR and FFR_CT were strongly correlated. The location of the lesion in RCA was associated with the highest diagnostic concordance between QFR and FFR_CT.     

Epicardial adipose tissue and myocardial ischemia assessed by computed tomography perfusion imaging and invasive fractional flow reserve

Background

Epicardial adipose tissue (EAT) is a metabolically active fat depot that is associated with incident coronary artery disease (CAD) and major adverse cardiovascular events. The relationship between EAT and myocardial ischemia remains unclear. This study investigated the relationship between EAT volume and the presence of perfusion defects on myocardial computed tomographic perfusion imaging (CTP) and functional stenoses on invasive fractional flow-reserve (FFR).

Potential utility of rubidium 82 pet quantification in patients with 3-vessel coronary artery disease

BACKGROUND: Standard perfusion imaging may underestimate the extent of disease in 3-vessel coronary atherosclerosis. This study determined whether positron emission tomography quantification of perfusion reserve by use of rubidium 82 net retention defined a greater extent of disease than the standard approach in patients with 3-vessel disease. METHODS AND RESULTS: Rb-82 net retention was quantified as an estimation of absolute perfusion at rest and with dipyridamole stress by use of dynamic positron emission tomography imaging. The percent of abnormal myocardial sectors, as compared with a normal database, for a standard and quantification approach was determined. Twenty-three patients were evaluated. Defect sizes were larger in patients with 3-vessel disease (n = 13) by use of quantification methods: 44% +/- 18% of the myocardial sectors were abnormal by use of the standard approach versus 69% +/- 24% of sectors when measured by quantification of the stress-rest perfusion difference (P =.008). In patients with single-vessel disease (n = 10), defect sizes were smaller with quantification methods. CONCLUSIONS: Quantification of Rb-82 net retention to measure the stress-rest perfusion difference in the myocardium defined a greater extent of disease than the standard approach in this group of patients with triple-vessel disease. More accurate measurement of the extent of coronary artery disease could facilitate better risk stratification and identify more high-risk patients in whom aggressive intervention is required.     

Assessment of myocardial perfusion by dynamic O-15-labeled water PET imaging: Validation of a new fast factor analysis

Background  Factor analysis (FA) is an established method for separating myocardium from blood pool by use of oxygen 15-labeled water and positron emission tomography for analyzing myocardial blood flow (MBF). Conventional FA methods generating images from sinograms (sinoFA) are time-consuming, whereas FA can be performed on the reconstructed images (reconFA) in a fraction of time. We validated the MBF values obtained by reconFA versus sinoFA. Methods and Results  In 23 volunteers (mean age, 26.6±3.4 years) MBF was calculated from sinoFA and reconFA and blindly reanalyzed 1 month later by the same observer. Intraobserver agreement and reconFA-versus-sinoFA agreement were assessed according to Bland and Altman (BA). Reproducibility proved excellent for global sinoFA (r=0.968; P<.001; BA limits, −0.617 to 0.676 mL·min⁻¹·g⁻¹) and slightly superior for reconFA (r=0.979; P<.001; BA limits, −0.538 to 0.558 mL·min⁻¹·g⁻¹), with wider limits of agreement for segmental MBF from sinoFA (r=0.777; P<.001; BA limits, −1.676 to 1.656 mL·min⁻¹·g⁻¹) and reconFA (r=0.844; P<.001; BA limits, −1.999 to 1.992 mL·min⁻¹·g⁻¹). In addition, sinoFA and reconFA showed excellent correlation (r=0.975, P<.001) and agreement (BA limits, −0.528 to 0.648 mL·min⁻¹·g⁻¹) for global and segmental values (r=0.955; P<.001; BA limits, −1.371 to 1.491 mL·min⁻¹·g⁻¹). Conclusions  Use of reconFA allows rapid and reliable quantitative MBF assessment with O-15-labeled water. This study was supported by a grant from the Swiss National Science Foundation (professorship grant PP00A-114706).     

Reduced myocardial flow reserve in anatomically normal coronary arteries due to elevated baseline myocardial blood flow in men with old myocardial infarction

BACKGROUND: Decreased myocardial flow reserve (MFR) in angiographically normal coronary arteries in patients with old myocardial infarction (OMI) has been reported. METHODS AND RESULTS: To clarify factors for the reduced MFR in OMI and to compare them with those in angina pectoris (AP), baseline myocardial blood flow (MBF) and MBF during dipyridamole administration were measured with nitrogen 13 ammonia positron emission tomography, after which MFR was calculated for 13 men with AP, 18 men with OMI, and 15 age-matched male control subjects. MFR was compared among the 3 groups in segments perfused by nonstenotic arteries. Baseline MBF in patients with OMI was significantly higher than that in patients with AP and control subjects. MBF during dipyridamole administration in patients with OMI was significantly lower than that in control subjects. MFR in patients with AP was 2.50 +/- 0.91 (P <.05 vs control subjects [3.47 +/- 1.25]), and that in patients with OMI was 1.83 +/- 0.61 (P <.01 vs control and AP groups). Ejection fraction (EF) in patients with OMI was significantly decreased compared with that in patients with AP. However, there was no significant difference in the mean score of the individual risk factors between patients with AP and those with OMI. In the pooled data with AP and OMI, baseline MBF and EF were significant for the reduced MFR. CONCLUSIONS: MFR and EF in patients with OMI were significantly decreased compared with those in patients with AP. Increased baseline MBF and decreased EF were significant factors for the reduced MFR in patients with AP and OMI.