Clinical assessment of myocardial perfusion with thallium-201

Assessment of myocardial perfusion and coronary blood flow in man can be performed reliably and successfully using thallium-201 imaging. The extent of exercise myocardial perfusion abnormalities reflects the functional significance of coronary artery stenosis. Accordingly, myocardial perfusion imaging is not only useful for the detection of coronary artery disease, but it also provides unique functional information which should be helpful in the management of patients with known coronary artery disease. The unfavorable physical properties of thallium-201 have limited to a certain extent full utilization of the clinical potential of the methodology. Now technetium-99m-labeled myocardial perfusion imaging agents promise to further enhance the clinical usefulness of myocardial perfusion imaging in patients.     

Usefulness and pitfalls in myocardial perfusion SPECT for detecting and assessing coronary artery disease

Thallium-201(Tl) is the dominant agent employed for myocardial perfusion imaging for detection of coronary artery disease, assessment of myocardial viability and prognostication. Technetium-99m(Tc) labeled radionuclides have been used as excellent alternatives to Tl. This paper will review the usefulness and pitfall in myocardial perfusion single photon emission computed tomography(SPECT) in patients with coronary artery disease. From a practical standpoint, we should know what are clinical questions, clinical status of patients(history and exercise ability of patients, obesity) and diagnostic accuracy of each diagnostic protocol and the performance in the nuclear laboratory. Myocardial perfusion defects during stress SPECT are produced by a heterogeneity in coronary blood flow, which depends on severity of coronary stenosis and consequent abnormalities in flow reserve. Certain factors can affect sensitivity and specificity of Tl SPECT for detection of coronary artery disease. Accurate determination of myocardial viability is vitally important for clinical decision making for patients with left ventricular(LV) dysfunction who will most benefit from revascularization. Hibernated myocardium may result in profound regional LV dysfunction in absence of necrosis. The various approach such as stress-redistribution-reinjection imaging, rest-redistribution imaging and rest-redistribution 24 hours delayed imaging has been utilized to assess myocardial viability with Tl. Alternatively, quantitative assessment of 99mTc-methoxy-isobutyl isonitrile(MIBI) and tetrofosmin uptake reflect the degree of viability. At the present time one of the most important clinical applications of exercise myocardial perfusion SPECT is the assessment of prognosis for patients with suspected and documented coronary artery disease. Patients with normal stress perfusion SPECT have a low event rate and excellent prognosis. Stress perfusion imagings have been widely used to stratify patients into different risk groups in the United State.     

腺苷负荷试验心肌灌注显像诊断冠心病的临床价值

目的　评价腺苷负荷试验心肌灌注显像诊断冠心病的准确性。方法　对 89例临床疑诊冠心病患者 ,分别静脉注射腺苷 ,剂量为 14 0 μg·kg-1·min-1,用药时间 6min(总剂量为 0 8mg/kg) ,注射过程中 ,行心电监测 ,观察患者的症状、血压和心率 ,于注射腺苷 3min末 ,静脉注射核素显像剂99mTc MIBI 92 5MBq ,1h后行心肌灌注断层显像 ,若显像异常 ,次日行静息心肌显像。所有患者行冠状动脉造影。结果　在 89例患者中 ,31例冠状动脉造影显示明显的冠状动脉狭窄病变 ,其中单支病变 10例 ,二支病变 11例 ,三支病变 10例。累及左前降支 2 8支 ,左回旋支 18支 ,右冠状动脉 16支 ,左主干 2支。腺苷负荷试验心肌灌注显像诊断冠心病的敏感性为 71%、特异性为 91%、阳性预测值81%、阴性预测值 84 %、准确性为 84 %。诊断单支、二支和三支冠状动脉病变患者的敏感性分别为5 0 %、73%、90 %。腺苷负荷试验心肌灌注显像判断血管病变的敏感性 77%、特异性 96 %、准确性 92 %。结论　腺苷负荷心肌灌注显像诊断冠心病敏感性及特异性均较高 ,具有重要的临床应用价值。     

The role of myocardial perfusion imaging in the diagnosis of patients with coronary artery disease: developments over the past year

PURPOSE OF REVIEW: The role of myocardial perfusion imaging in the diagnosis of coronary artery disease in various patient populations has been expanding. Recent literature from March 2004 to February 2005 has advanced the concept of attenuation correction and electrocardiographic gating in improving the diagnosis of coronary artery disease. RECENT DEVELOPMENTS: The American Heart Association encourages the use of electrocardiographic-gated single photon emission computerized tomography in women. Asymptomatic diabetic patients may benefit from screening with myocardial perfusion imaging. Dobutamine stress perfusion imaging is an important diagnostic tool in elderly patients who are unable to exercise. In patients with chest pain, acute imaging may decrease unnecessary admissions. Vasodilator stress imaging has high sensitivity and specificity in patients with left bundle branch block. Patients undergoing endovascular stent grafting may benefit from risk stratification with vasodilator myocardial perfusion imaging. The American Society of Nuclear Cardiology and the Society of Nuclear Medicine have recognized the role of attenuation correction in increasing the diagnostic accuracy of myocardial perfusion imaging. Multiple studies emphasize the importance of electrocardiographic gating in myocardial perfusion imaging. SUMMARY: Recent developments have resulted in an important statement by the American Heart Association that assigns a larger role for myocardial perfusion imaging in the diagnosis of coronary artery disease in women. The role of myocardial perfusion imaging is also expanding in various other patient populations. The literature has validated the concept of attenuation correction for the accurate assessment of attenuation artifacts as well as electrocardiographic gating in enhancing the diagnosis and risk stratification for coronary artery disease.     

腺苷负荷试验心肌核素显像对冠心病诊断价值的评估

目的分析腺苷负荷试验心肌核素显像对于冠心病诊断的敏感性、特异性及其特点。方法住院患者同时行冠状动脉（冠脉）造影和腺苷负荷试验心肌核素显像。腺苷总量为840μg／kg,6min匀速静脉泵入,腺苷泵入3min时静脉推注^99m锝-甲氧基异丁基异腈核素显像925MBq,1．5h后进行心肌断层显像,若异常,次日行静息心肌显像。结果冠脉造影阳性50例中,心肌核素显像阳性44例。29例冠脉造影无明显狭窄,其中19例心肌核素显像阴性。腺苷负荷试验心肌核素显像对于冠心病诊断的敏感性和特异性为88．O％和65．5％。前降支病变40例,心肌核素前壁区域低灌注32例,回旋支病变27例,侧壁区域低灌注21例,右冠脉病变32例,下壁区域低灌注31例,右冠脉病变较前降支或回旋支病变的心肌核素显像阳性率高（P〈0．05）。结论腺苷负荷试验心肌核素显像对于冠心病诊断的敏感性、特异性较高。     

Stress myocardial perfusion imaging in the diagnosis and prognosis of women with suspected coronary artery disease

Coronary artery disease is the single largest killer of women in the United States and claims the lives of more than 250,000 women each year. For several decades, there was the misperception that coronary artery disease was a "man's disease." The fact is that women are indeed vulnerable to coronary artery disease; however, they typically develop the disease 10 to 15 years later than men. Once coronary artery disease is evident, women have worse outcomes as compared with men.Therefore, early and accurate diagnosis of coronary artery disease is crucial for reducing heart disease mortality in women. Stress myocardial perfusion imaging using contemporary techniques has been shown to have significant value in the diagnosis and prognosis of coronary artery disease in women. Myocardial perfusion imaging with exercise or pharmacologic stress has been shown to add incremental value to the use of clinical variables or exercise electrocardiogram stress testing alone in the risk stratification of women with an intermediate clinical pretest likelihood of coronary artery disease. This review provides an overview of the role of stress myocardial perfusion imaging in the clinical evaluation of women with suspected coronary artery disease.     

腺苷负荷心肌灌注显像141例临床分析

目的:腺苷负荷心肌灌注显像(MPI)与冠状动脉造影(CAG)2种检查方法的结果对比分析。方法:对141例患者分别行腺苷负荷MPI及CAG检查,并使用校正的TIMI血流分级(CTFC)方法评价冠状动脉血流速度。对2种方法的检查结果进行比较分析。结果:腺苷负荷MPI阳性的99例患者中,经CAG检查确诊冠心病者52例,冠状动脉慢血流(CSF)者37例,冠状动脉正常者10例。腺苷负荷MPI对冠心病诊断的灵敏度和特异度为92.9%和44.7%;对CSF诊断的灵敏度和特异度为82.2%和75.0%。结论:腺苷负荷MPI阳性者中一部分为冠心病患者,一部分为CSF者,对于腺苷负荷MPI异常的患者需进一步行CAG检查以明确病情。     

Economics of myocardial perfusion imaging in Europe--the EMPIRE Study.

BACKGROUND: Physicians use myocardial perfusion imaging to a variable extent in patients presenting with possible coronary artery disease. There are few clinical data on the most cost-effective strategy although computer models predict that routine use of myocardial perfusion imaging is cost-effective. OBJECTIVES: To measure the cost-effectiveness of four diagnostic strategies in patients newly presenting with possible coronary artery disease, and to compare cost-effectiveness in centres that routinely use myocardial perfusion imaging with those that do not. METHODS: We have studied 396 patients presenting to eight hospitals for the diagnosis of coronary artery disease. The hospitals were regular users or non-users of myocardial perfusion imaging with one of each in four countries (France, Germany, Italy, United Kingdom). Information was gathered retrospectively on presentation, investigations, complications, and clinical management, and patients were followed-up for 2 years in order to assess outcome. Pre- and post-test probabilities of coronary artery disease were computed for diagnostic tests and each test was also assigned as diagnostic or part of management. Diagnostic strategies defined were: 1: Exercise electrocardiogram/coronary angiography, 2: exercise electrocardiogram/myocardial perfusion imaging/coronary angiography, 3: myocardial perfusion imaging/coronary angiography, 4: coronary angiography. Primary outcome measures were the cost and accuracy of diagnosis, the cost of subsequent management, and clinical outcome. Secondary measures included prognostic power, normal angiography rate, and rate of angiography not followed by revascularization. RESULTS: Mean diagnostic costs per patient were: strategy 1: 490 Pounds, 2: 409 Pounds, 3: 460 Pounds, 4: 1253 Pounds (P < 0.0001). Myocardial perfusion imaging users: 529 Pounds, non-users 667 Pounds (P = 0.006). Mean probability of the presence of coronary artery disease when the final clinical diagnosis was coronary artery disease present were, strategy 1: 0.85, 2: 0.82, 3: 0.97, 4: 1.0 (P < 0.0001), users 0.93, non-users 0.88 (P = 0.02), and when coronary artery disease was absent, 1: 0.26, 2: 0.22, 3: 0.16, 4: 0.0 (P < 0.0001), users 0.21, non-users 0.20 (P = ns). Total 2-year costs (coronary artery disease present/absent) were: strategy 1: 4453 Pounds/710 Pounds, 2: 3842 Pounds/478 Pounds, 3: 3768 Pounds/574 Pounds, 4: 5599 Pounds/1475 Pounds (P < 0.05/0.0001), users: 5563 Pounds/623 Pounds, non-users: 5428 Pounds/916 Pounds (P = ns/0.001). Prognostic power at diagnosis was higher (P < 0.0001) and normal coronary angiography rate lower (P = 0.07) in the scintigraphic centres and strategies. Numbers of soft and hard cardiac events over 2 years and final symptomatic status did not differ between strategy or centre. CONCLUSION: Investigative strategies using myocardial perfusion imaging are cheaper and equally effective when compared with strategies that do not use myocardial perfusion imaging, both for cost of diagnosis and for overall 2 year management costs. Two year patient outcome is the same.     

The significance of exercise-induced Q waves.

The significance of transient exercise-induced Q waves present during treadmill testing was prospectively evaluated and correlated with the findings at cardiac catheterization. Exercise-induced Q waves were present in 14 of 560 patients (2.5 per cent) undergoing treadmill exercise testing. Thirteen patients had Q waves in leads V1 through V3 and one patient had Q waves in leads II, III and aVF. Ten patients underwent cardiac catheterization; six did not have coronary artery disease as determined by angiography. Two patients had a documented anterior myocardial infarction and did not undergo cardiac catheterization. Exercise myocardial perfusion imaging was performed in 10 patients. Six patients without coronary artery disease had no evidence of exercise perfusion defects. In the four patients with coronary artery disease, three patients had an abnormal resting perfusion study without change with exercise and one patient had a new exercise myocardial perfusion defect. We conclude that exercise-induced transient Q waves are not diagnostic of underlying coronary disease. In patients without coronary artery disease the mechanism of exercise-induced Q waves is as yet unclear. In patients with coronary artery disease, the mechanism may also be undefined or secondary to myocardial ischemia.     

Myocardial perfusion abnormalities in treated hypertensive patients without known coronary artery disease

OBJECTIVE: Myocardial perfusion abnormalities may occur in hypertensive patients in absence of significant coronary artery disease. However, it is not well established whether hypertensive patients without known coronary artery disease have a higher prevalence or extent of myocardial perfusion abnormalities compared with normotensive patients with similar clinical features. DESIGN: This study compares the prevalence and extent of rest and stress-induced myocardial perfusion abnormalities in patients with and without hypertension. METHODS: Dobutamine (up to 40 microg/kg per min) stress technetium-99m myocardial perfusion SPECT imaging was performed for evaluation of myocardial ischaemia in 350 patients (mean age = 60+/-13 years, 146 men) without known coronary artery disease. One hundred and forty-eight patients were hypertensive. Rest SPECT images were acquired 24 h after the test Abnormal perfusion was defined as the presence of reversible or fixed perfusion defects. RESULTS: No significant difference was detected between patients with and without hypertension regarding gender, prevalence of symptoms, risk factors, pretest probability of coronary artery disease (52+/-28 versus 53+/-29%), peak rate pressure product (21040+/-4755 versus 20774+/-4865) or number of patients achieving the target heart rate during stress (85 versus 86%). Hypertensive patients were significantly older (62+/-11 versus 58+/-13 years, P = 0.005) and were receiving beta-blockers more frequently (34 versus 18%, P = 0.0001). The prevalence of myocardial perfusion abnormalities was similar in patients with and without hypertension (28 versus 31% in patients with low, 38 versus 33% in patients with intermediate and 60 versus 58% in patients with high pretest probability of coronary artery disease, respectively). No significant difference was detected between the two groups regarding stress perfusion defect score (1.45+/-2.5 versus 1.50+/-2.6) or rest score (0.72+/-1.8 versus 0.68+/-1.6). CONCLUSION: Treated hypertensive patients without known coronary artery disease have a similar prevalence and severity of myocardial perfusion abnormalities at rest and at dobutamine stress compared with normotensive patients with similar clinical characteristics.     

Stress echocardiography versus myocardial SPECT for risk stratification of patients with coronary artery disease

PURPOSE OF REVIEW: Diagnostic testing using noninvasive imaging has become an integral part of risk stratification in patients with coronary artery disease. It is important to understand the integral strengths and weaknesses between the different modalities of stress testing and to apply accurately the type of test the clinical scenario demands. RECENT FINDINGS: There have been tremendous advances made in the field of cardiac imaging. Both myocardial perfusion imaging and stress echocardiographic techniques continue to evolve and play an important role in the assessment of patients with coronary artery disease. SUMMARY: In this review the authors discuss the relative merits of both stress echocardiography and myocardial single photon emission computed tomographic imaging for diagnosis and risk stratification of patients with coronary artery disease.     

Assessment of Ischemic Heart Disease Using Magnetic Resonance First-Pass Perfusion Imaging

METHODS: Cardiovascular magnetic resonance (MR) perfusion imaging has matured to a point where it can be routinely applied to assess patients with coronary artery disease and ischemic cardiomyopathy. The method has been compared to invasive, catheter-based as well as other noninvasive imaging modalities (echocardiography, single-photon emission computed tomography [SPECT], and positron emission tomography [PET]) for the evaluation of patients with coronary artery disease. Besides qualitative evaluation of MR perfusion images, an absolute quantification of global, regional and transmural myocardial perfusion is possible. A relative or absolute myocardial perfusion reserve has been determined noninvasively with MR perfusion imaging, and can provide good agreement with the invasive assessment. Based on the perfusion reserve, the severity of an epicardial coronary stenosis can be evaluated in patients with known or suspected coronary artery disease. Besides the absence of radiation exposure, MR perfusion imaging offers good temporal and excellent spatial resolution. In particular, the spatial resolution increases the sensitivity and specificity for the detection of coronary artery disease. New parameters such as the "endo-/epimyocardial resting perfusion ratio", may under some circumstances sufficiently enhance the sensitivity for detecting an abnormal perfusion, and thus avoid potentially harmful and expensive stress testing in patients with suspected ischemic heart disease. New revascularization modalities such as therapeutic angiogenesis need to be matched by sensitive imaging tools to prove their benefits. Thus, the optimization of therapeutic angiogenesis may profit from the diagnostic advantages provided by MR perfusion imaging. Furthermore, MR might yield new insights into the pathophysiology of cardiac diseases such as "syndrome X", or might help in the repetitive assessment of heart transplant recipients, possibly obviating the need for further invasive testing. CONCLUSION: The breadth of cardiac MRI allows the combined noninvasive assessment of myocardial perfusion, function, as well as myocardial viability. The combination gives MRI a unique and strong position in the field of noninvasive diagnostic cardiology.     

Principal uses of myocardial perfusion scintigraphy in the management of patients with known or suspected coronary artery disease

The use of myocardial perfusion single photon emission computed tomography (SPECT) has undergone considerable expansion and evolution over the past 2 decades. Although myocardial perfusion imaging was first conceived as a noninvasive diagnostic tool for determining the presence or absence of coronary artery disease, its prognostic value is now well established. Thus, identification of patients at risk for future cardiac events has become a primary objective in the noninvasive evaluation of patients with chest pain syndromes and among patients with known coronary artery disease. In particular, the ability of myocardial perfusion SPECT to identify patients at low (< 1%), intermediate (1% to 5%) or high (> 5%) risk for future cardiac events is essential to patient management decisions. Moreover, previous studies have conclusively shown the incremental prognostic value of myocardial perfusion SPECT over clinical and treadmill exercise data in predicting future cardiac events. This report addresses the current role and new developments, with respect to the use of myocardial perfusion imaging, in determining patient risk for cardiac events and the cost-effective integration of such information into patient management decisions.     

磁共振心肌灌注成像对老年冠心病的诊断价值

目的　探讨磁共振心肌灌注成像对老年冠心病的诊断价值。方法　对临床确诊的 35例冠心病患者 ,利用磁共振心肌灌注成像方法得到心肌灌注时间 -信号强度曲线 ,观察曲线的上升斜率和信号强度的峰值。并同期作了冠脉造影 ,确定心肌异常改变与冠脉病变血管分布相对应关系。结果　 33例经心肌灌注成像有 41个病灶呈低灌注区为心肌缺血 ,其中 5例出现延迟强化为心肌梗死 ,经冠脉造影证实 35例均有不同程度的冠脉狭窄。结论　磁共振心肌灌注成像与冠脉造影检查结果无明显差异 ,具有高度的一致性。而磁共振心肌灌注成像是一种无创性测定心肌血流的检查方法 ,为及时诊断及恰当治疗冠心病提供可靠的依据     

Outcomes in patients with abnormal myocardial perfusion imaging and normal coronary angiogram

A subset of subjects undergoing myocardial perfusion imaging has perfusion abnormalities that are subsequently labeled false positive based on coronary angiography. We evaluated the long-term prevalence of cardiovascular events in these patients. We retrospectively identified 48 patients who had reversible perfusion abnormalities with myocardial perfusion imaging and normal coronary angiography. Patients with known coronary artery disease, left ventricular dysfunction, valvular disease, and cardiomyopathy were excluded. Patient follow-up, conducted for at least 3 (mean interval, 7.4) years from the index myocardial perfusion imaging, was accomplished by a review of medical records and telephone interviews. Study endpoints were cardiovascular events defined as sudden cardiac death, myocardial infarction, percutaneous coronary revascularization, coronary artery bypass grafting, and cerebrovascular or peripheral revascularization. Thirty-one percent (15 of 48) of the patients had cardiovascular events. Six of the 48 patients had coronary events. These patients had abnormal myocardial perfusion imaging and normal coronary angiogram. The time between myocardial perfusion imaging and coronary event was 0.5 to 8.67 years. There was a strong correlation between the regions of original perfusion abnormality and the ultimate coronary ischemia or revascularization. Abnormal findings on myocardial perfusion imaging may predict a higher prevalence of coronary and peripheral vascular events than suggested by a normal coronary angiogram.     

Myocardial Perfusion Imaging with Cardiac Computed Tomography: State of the Art

Cardiac computed tomography (CCT) has become an important tool for the anatomic assessment of patients with suspected coronary disease. Its diagnostic accuracy for detecting the presence of underlying coronary artery disease and ability to risk stratify patients are well documented. However, the role of CCT for the physiologic assessment of myocardial perfusion during resting and stress conditions is only now emerging. With the addition of myocardial perfusion imaging to coronary imaging, CCT has the potential to assess both coronary anatomy and its functional significance with a single non-invasive test. In this review, we discuss the current state of CCT myocardial perfusion imaging for the detection of myocardial ischemia and myocardial infarction and examine its complementary role to CCT coronary imaging.     

Fusion imaging: Combined visualization of 3D reconstructed coronary artery tree and 3D myocardial scintigraphic image in coronary artery disease

Background: In patients with coronary artery disease, coronary angiography is performed for assessment of epicardial coronary artery stenoses. In addition, myocardial scintigraphy is commonly used to evaluate regional myocardial perfusion. These two-dimensional (2D) imaging modalities are typically reviewed through a subjective, visual observation by a physician. Even though on the analysis of 2D display scintigraphic myocardial perfusion segments are arbitrarily assigned to three major coronary artery systems, the standard myocardial distribution territories of the coronary tree correspond only in 50–60% of patients. On the other hand, the mental integration of both 2D images of coronary angiography and myocardial scintigraphy does not allow an accurate assignment of particular myocardial perfusion regions to the corresponding vessels. To achieve an objective assignment of each vessel segment of the coronary artery tree to the corresponding myocardial regions, we have developed a 3D fusion image technique and applied it to patients with coronary artery disease. The morphological data (coronary angiography) and perfusion data (myocardial scintigraphy) are displayed in a 3D format, and these two 3D data sets are merged into one 3D image. Results: Seventy-eight patients with coronary artery disease were studied with this new 3D fusion technique. Of 162 significant coronary lesions, 120 (74%) showed good coincidence with regional myocardial perfusion abnormality on 3D fusion image. No regional myocardial perfusion abnormality was found in 44 (26%) lesions. Furthermore, the 3D fusion image revealed 24 ischemic myocardial regions that could not be related to angiographically significant coronary artery lesions. Conclusion: The results of this study demonstrate that our newly developed 3D fusion technique is useful for an accurate assignment of coronary vessel segments to the corresponding myocardial perfusion regions, and suggest that it may be helpful to improve the interpretative and decision-making process in the treatment of patients with coronary artery disease.     

锝-氮-氮欧乙替心肌灌注显像对冠心病的诊断评价

目的评价锝-氮-氮欧乙替（^99mTc-N—NOET）心肌灌注显像检测冠心病的价值。方法对42例临床疑诊冠心病患者,行^99mTc-N-NOET运动负荷和再分布心肌灌注显像,所有患者行冠状动脉造影检查。结果在42例患者中,26例冠状动脉造影显示有冠状动脉狭窄病变,其中单支病变10例,二支病变7例,三支病变9例.^99mTc-N-NOET心肌显像检出心肌缺血或心肌梗死21例,未检出异常5例;16例冠状动脉造影正常患者,^99mTc-N-NOET心肌显像正常14例,异常2例.^99mTc-N-NOET心肌灌注显像诊断冠心病的敏感性为81％、特异性为88％、阳性预测值91％,阴性预测值74％,预测准确性为83％。诊断单支、二支和三支冠状动脉病变的敏感性分别为60％（6／10）、86％（6／7）、100％（9／9）。42例均无干扰心肌分辨的肺、肝重度摄取增高者。15min运动负荷显像肺脏摄取高,尤以冠状动脉狭窄患者增高明显。结论 ^99mTc-N-NOET心肌灌注显像检测冠心病敏感性、特异性较高,早期显像肺摄取增加与有意义的冠状动脉病变有关。     

Stress nuclear myocardial perfusion imaging versus stress echocardiography: prognostic comparisons

The use of noninvasive stress cardiac imaging for stratifying risk in patients with known or suspected coronary artery disease is growing as a tool for identification of the subgroup most likely to benefit from the expense and risk of more invasive procedures, including cardiac catheterization and coronary revascularization. In this setting, it is especially important that a test be able to identify patients with sufficiently low risk that clinicians are comfortable in deferring such interventions, especially in those with other markers of increased risk. Previous data have shown that cardiac risk is most closely related to the presence and extent of jeopardized viable myocardium on noninvasive stress cardiac imaging. Although stress echocardiography may have comparable ability to detect coronary artery disease, current data suggest that stress echocardiography detects significantly less jeopardized viable myocardium than stress nuclear myocardial perfusion imaging and consequently fewer patients at risk for cardiac events. Stress nuclear myocardial perfusion imaging may therefore have important advantages for risk stratification and the direction of future care of patients with known or suspected coronary artery disease.     

MRI for the diagnosis of myocardial ischemia and viability

Assessment of myocardial ischemia and viability plays a crucial role in the clinical management of patients with coronary artery disease. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. MRI is able to evaluate both myocardial perfusion as well as myocardial contractile reserve. Because of its superior spatial resolution, integration of qualitative and quantitative methodology, and excellent reproducibility, MRI has advantages over conventional noninvasive modalities currently used in the evaluation of myocardial ischemia and viability, and may well emerge as the premier noninvasive technique in the assessment of patients with coronary artery disease. The authors review the rapidly expanding recent literature that has now established cardiovascular MRI (including dobutamine cine MRI and vasodilator perfusion MRI techniques) as an ideal choice in the evaluation of myocardial ischemia and delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of viability. Comparisons with more established techniques such as dobutamine stress echocardiography, single photon emission computed tomography perfusion imaging, and positron emission tomography are reviewed.