99mTc-MIBI门电路SPECT对冠心病的诊断和心肌存活性评价的作用

为进一步评价99m锝-甲氧基异睛(99mTc-MIBI)门电路和非门电路单光子发射断层显像(SPECT)对冠心病的诊断价值及硝酸甘油介入诊断试验在心肌存活状态评价中的作用,对40例进行运动心肌灌注断层显象,并与冠状动脉(冠脉)造影比较.结果32例冠脉造影显示冠脉有意义狭窄.门电路断层显象对冠心病诊断总的敏感和特异性分别为93.8%和87.5%;非门电路断层显象分别为84.4%和87.5%,两相比较,无显著性差异(P＞0.05).对冠脉病变支数诊断敏感性门电路方法优于非门电路方法(分别为73.8%和62.3%,P＜0.05).特异性均为96.6%.20例进行含服硝酸甘油后静态心肌灌注断层显象,16例心肌梗死病人中有3例为部分可逆性心肌灌注缺损,4例慢性心肌缺血病人,全部有可逆性心肌灌注.表明硝酸甘油介入诊断试验有助于心肌灌注异常可逆性的评估;99mTc-MIBI门电路SPECT和硝酸甘油介入诊断试验是有效的对冠心病无创性诊断和心肌存活状态评价方法.     

Value of gated SPECT myocardial perfusion imaging for individual cardiac risk assessment

Myocardial perfusion imaging enables not only accurate diagnosis of disease but also entails prognostic value. Myocardial perfusion SPECT contributes to assessment of future cardiac events independently of other clinical parameters. A normal stress myocardial perfusion scan is associated with a favorable prognosis independent of history, symptoms, and exercise electrocardiography test variables. Cardiac risk and benefit from invasive therapeutic strategies increase in relation to the severity of the abnormality of perfusion and function assessed by gated myocardial perfusion SPECT. Thus, stress myocardial perfusion imaging may serve as a gatekeeper for referral to coronary angiography enabling effective risk stratification in patients with suspected or documented coronary artery disease.     

The Value of Upsloping ST Depression in Diagnosing Myocardial Ischemia

We evaluated the value of upsloping ST‐segment depression in predicting the severity of myocardial ischemia. Comparison of the exercise electrocardiographic changes was made to myocardial perfusion images and coronary angiograms as the criteria for ischemia. We retrospectively reviewed 621 patients who underwent exercise technetium‐99m tetrofosmin single photon emission computed tomography (SPECT) for the assessment of suspected or known coronary artery disease followed by coronary angiography within a 3‐month period. The test sensitivity and specificity of 1 mm horizontal or downsloping ST depression in predicting reversible ischemia as assessed by gated SPECT imaging (GSI) were 65% and 87%, respectively. The corresponding values were 67% and 94% compared to coronary angiography. The sensitivity and specificity of gated SPECT imaging compared to coronary angiography were 78% and 89%. On the other hand when 1 mm upsloping ST depression at 70 ms past the J‐point was regarded as abnormal, along with horizontal and downsloping, the sensitivity and specificity were 82% and 90% compared to myocardial perfusion imaging, and 77% and 92% as assessed by coronary angiography. We conclude that upsloping ST‐segment depression is associated with an increased risk of coronary artery disease and is a valuable predictor of myocardial ischemia.     

Nuclear cardiology: present and future

Nuclear cardiology has made significant advances since the first reports of planar scintigraphy for the evaluation of left ventricular perfusion and function. While the current "state of the art" of gated myocardial perfusion single-photon emission computed tomographic (SPECT) imaging offers invaluable diagnostic and prognostic information for the evaluation of patients with suspected or known coronary artery disease (CAD), advances in the cellular and molecular biology of the cardiovascular system have helped to usher in a new modality in nuclear cardiology, namely, molecular imaging. In this review, we will discuss the current state of the art in nuclear cardiology, which includes SPECT and positron emission tomographic evaluation of myocardial perfusion, evaluation of left ventricular function by gated myocardial perfusion SPECT and gated blood pool SPECT, and the evaluation of myocardial viability with PET and SPECT methods. In addition, we will discuss the future of nuclear cardiology and the role that molecular imaging will play in the early detection of CAD at the level of the vulnerable plaque, the evaluation of cardiac remodeling, and monitoring of important new therapies including gene therapy and stem cell therapy.     

Gated single-photon emission computed tomographic myocardial imaging: a new tool in clinical cardiology

BACKGROUND: Gated single-photon emission computed tomography (gated SPECT) myocardial perfusion imaging allows the analysis of left ventricular (LV) perfusion and function during the same acquisition. RESULTS: Gated SPECT provides additional information to myocardial perfusion, which improves test specificity in patients with known or suspected coronary artery disease and hence diminishes the amount of borderline diagnosis. Because gated SPECT provides reliable information on LV ejection fraction and LV volumes, it is also a valuable tool in risk stratification. In addition, from gated SPECT, images can be reconstructed from which wall motion can be assessed showing a good correlation with wall motion assessed by accepted imaging modalities as echocardiography, magnetic resonance imaging, and contrast angiography. In the future wall motion analysis from gated SPECT may also be used for revascularization stratification. CONCLUSIONS: Gated SPECT gives important additional information beyond myocardial perfusion imaging alone, which could have major clinical implications for optimal patient management.     

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.     

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 (> or = 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 (> or = 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.     

Clinical validation of technetium-99m MIBI-gated single-photon emission computed tomography (SPECT) for avoiding false positive results in patients with left bundle-branch block: comparison with stress-rest nongated SPECT

BACKGROUND: Septal perfusion defects are common on myocardial perfusion single-photon emission computed tomography (SPECT) slices in patients with left bundle-branch block (LBBB) in the absence of coronary artery disease. HYPOTHESIS: The use of gated myocardial perfusion SPECT imaging in such patients should be clinically validated. The aims of this study were, therefore, to validate clinically the use of gated myocardial SPECT imaging to avoid false positive septal perfusion defects in patients with LBBB and to compare nongated and gated SPECT imaging techniques in the same patients in the same imaging session. METHODS: We performed stress-rest myocardial perfusion SPECT and resting gated SPECT using Technetium-99m MIBI in 25 patients with LBBB and in 6 control subjects. Stress-rest SPECT images and end-diastolic and end-systolic gated SPECT slices were assessed visually and quantitatively (septum/lateral wall count ratio). Coronary angiography was performed in 15 patients with LBBB and in all 6 control subjects. RESULTS: Stress-rest (nongated) SPECT slices and end-diastolic and end-systolic gated SPECT images were normal in all control subjects. Stress-rest (nongated) SPECT imaging revealed septal perfusion defect in 20 (11 reversible, 9 irreversible) patients with LBBB, whereas the figures were 15 and 5 for end-systolic and end-diastolic gated SPECT images, respectively. Coronary angiography results were normal in all control subjects and in 15 patients with LBBB. Quantitative analysis of gated SPECT images revealed no statistically significant difference between patients with LBBB and control subjects in end-diastolic mean septum/lateral wall count values (0.86 +/- 0.19 in LBBB vs. 0.98 +/- 0.15 in normal subjects, p > 0.05), but the difference was statistically significant for end-systolic, stress, and rest values (p < 0.001 for all). CONCLUSION: Gated SPECT imaging, particularly end-diastolic images, revealed fewer false positive results and thus can be used to avoid false positive septal perfusion defects commonly seen in stress-rest (nongated) myocardial perfusion SPECT in patients with LBBB.     

Usefulness of combination post-stress dysfunction and perfusion imaging in technetium-99m-tetrofosmin myocardial scintigraphy

OBJECTIVES: Myocardial perfusion imaging has lower sensitivity for the diagnosis of coronary artery disease in patients with three-vessel disease. The presence of post-stress dysfunction of the left ventricle, evaluated by electrocardiography(ECG) gated single photon emission computed tomography(SPECT) with a quantitative gated SPECT program, was investigated in patients with coronary artery disease, and also whether combining post-stress dysfunction and myocardial perfusion imaging improved the diagnosis of coronary artery disease. METHODS: ECG gated technetium-99m-tetrofosmin SPECT was performed using a one day, stress and rest, protocol in 139 patients. SPECT and coronary angiography were performed within 1 month. The coronary artery disease group consisted of 89 patients: 43 with one-vessel disease(1VD), 28 with two-vessel disease(2VD), and 18 with three-vessel disease(3VD). The group with zero-vessel disease(0VD) consisted of 50 patients. According to post-stress and rest ejection fraction(EF) and end-systolic volume (ESV), post-stress dysfunction is defined as follows: rest EF--post-stress EF > or = 5% and post-stress ESV--rest ESV > or = 5 ml. RESULTS: In the coronary artery disease group, post-stress ESV was larger than rest ESV(37.8 +/- 26.4, 34.0 +/- 24.2 ml, p < 0.001), and post-stress EF was lower than rest EF (61.5 +/- 11.1%, 64.2 +/- 10.8%, p < 0.001). In the 0VD group, ESV and EF were the same for post-stress and rest (25.7 +/- 20.8, 26.2 +/- 21.6 ml, NS; 70.4 +/- 9.5%, 70.0 +/- 9.6%, NS). Post-stress dysfunction was 6.0% in the 0VD group and 30.3% in the coronary artery disease group(p < 0.001). Furthermore, post-stress dysfunction in the 2VD (35.7%) and 3VD(38.9%) groups was higher than that in the 0VD group(p < 0.01, p < 0.01). Sensitivity of coronary artery disease diagnosis by myocardial perfusion imaging was 75%. The combination of post-stress dysfunction and myocardial perfusion imaging improved sensitivity from 75% to 82%(p < 0.05), but reduced the specificity from 92% to 86%(p = 0.08). CONCLUSIONS: Post-stress dysfunction is a useful parameter for clinical diagnosis of coronary artery disease.     

Functional assessment with electrocardiographic gated single-photon emission computed tomography improves the ability of technetium-99m sestamibi myocardial perfusion imaging to predict myocardial viability in patients undergoing revascularization

This study evaluates the use of electrocardiographic (ECG) gated single-photon emission computed tomographic (SPECT) myocardial perfusion imaging for the prediction of viability in patients undergoing revascularization, who have coronary disease and left ventricular dysfunction. Fifty patients underwent technectium-99m (Tc-99m) sestamibi ECG gated SPECT imaging preoperatively at rest and 1 week after revascularization, whereas 36 (72%) also underwent imaging 6 weeks after revascularization. Images were interpreted by the consensus of 3 experienced readers without knowledge of patient identity or time of imaging (pre- or postrevascularization) for perfusion and wall motion using a 17-segment model. Results of perfusion alone were compared with perfusion and wall motion combined. One hundred five coronary artery territories were revascularized, 96 of which were viable and 9 nonviable. Perfusion alone predicted 87 to be viable and 18 nonviable (sensitivity 86%, specificity 55%, positive predictive value 95%, negative predictive value 28%, and overall accuracy 85%). Perfusion and wall motion combined identified 95 territories to be viable (sensitivity 95%; p <0.025; specificity 55%, positive predictive value 96%, negative predictive value 50%, and overall accuracy 91%; p <0.05). Thus, Tc-99m sestamibi ECG gated SPECT myocardial perfusion imaging at rest allows assessment of both perfusion and wall motion, which significantly improves the sensitivity and overall accuracy for determination of viability in comparison with perfusion alone.     

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.     

Major advances in single-photon emission computed tomography perfusion imaging

Major advances in single-photon emission computed tomography (SPECT) myocardial perfusion imaging have been realized with the introduction of state-of-the-art imaging equipment and radiopharmaceuticals. Gated tomographic myocardial perfusion imaging with technetium-99m (Tc-99m)-labeled radiopharmaceuticals provides a combined evaluation of both myocardial perfusion and function. Left ventricular ejection fraction can be measured accurately from the gated SPECT images. Recently, hardware and software have been introduced, which minimize the effect of soft tissue attenuation, thereby improving test specificity in the diagnosis of coronary artery disease. Myocardial viability may be assessed with the use of rest/delayed thallium-201 SPECT or F-18 fluorodeoxyglucose SPECT with modified scintillation camera collimation and electronics, or coincidence detection. Imaging patients to assess myocardial infarction or resting ischemia in the emergency department has expedited patient care and improved cost effectiveness. Teleradiography has also facilitated the interpretation of studies performed in the emergency department and at remote facilities, likewise improving cost-effectiveness.     

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease

Technetium-99m (Tc-99m) sestamibi is a new myocardial perfusion imaging agent that offers significant advantages over thallium-201 (Tl-201) for myocardial perfusion imaging. The results of the current clinical trials using acquisition and processing parameters similar to those for Tl-201 and a separate (2-day) injection protocol suggest that Tc-99m sestamibi and Tl-201 single photon emission computed tomography (SPECT) provide similar information with respect to detection of myocardial perfusion defects, assessment of the pattern of defect reversibility, overall detection of coronary artery disease (CAD) and detection of disease in individual coronary arteries. Tc-99m sestamibi SPECT appears to be superior to Tc-99m sestamibi planar imaging because the former provides a higher defect contrast and is more accurate for detection of disease in individual coronary arteries. Research is currently under way addressing optimization of acquisition and processing of Tc-99m sestamibi studies and development of quantitative algorithms for detection and localization of CAD and sizing of transmural and nontransmural myocardial perfusion defects. It is expected that with the implementation of the final results of these new developments, further significant improvement in image quality will be attained, which in turn will further increase the confidence in image interpretation. Development of algorithms for analysis of end-diastolic myocardial images may allow better evaluation of small and nontransmural myocardial defects. Furthermore, gated studies may provide valuable information with respect to regional myocardial wall motion and wall thickening. With the implementation of algorithms for attenuation and scatter correction, the overall specificity of Tc-99m sestamibi SPECT should improve significantly because of a substantial decrease in the occurrence of attenuation-related image artifacts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of SPECT using technetium-99m agents and thallium-201 and PET for the assessment of myocardial perfusion and viability

This report reviews the applications of tomographic imaging with current and new tracers in assessing myocardial perfusion and viability. Multiple studies with thallium-201 (TI-201) single photon emission computed tomography (SPECT) imaging for the detection of coronary artery disease (CAD) have demonstrated high sensitivity, high rates of normalcy and high reproducibility. In assessing viability, fixed defects are frequently detected in viable zones in 4-hour studies with TI-201 imaging. Redistribution imaging performed 18 to 72 hours after injection or reinjection of TI-201 before 4-hour redistribution imaging has been shown to improve accuracy of viability assessment. TI-201 SPECT studies are limited by the suboptimal physical properties of TI-201, which result in variable image quality. The 2 new technetium-99m (Tc-99m) - labeled myocardial perfusion tracers offer the ability to inject much higher amounts of radioactivity, making it possible to assess ventricular function as well as myocardial perfusion from the same injection of radiotracer. Tc-99m sestamibi has very slow myocardial clearance, which allows for prolonged imaging time and results in image quality superior to that obtained with TI-201 and Tc-99m teboroxime. The combination of minimal redistribution of Tc-99m sestamibi and high count rates makes gated SPECT imaging feasible, and also permits assessment of patients with acute ischemic syndromes by uncoupling the time of injection from the time of imaging. The combination of high image quality and first-pass exercise capabilities may lead to a choice of this agent over TI-201 for assessment of chronic CAD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Failure of gated SPECT and echocardiography to detect large apical aneurysm secondary to hyperdynamic left ventricular wall at the aneurysm neck

We present a patient with a history of coronary artery disease and exertional angina after an acute anterior myocardial infarction. Angiography and ventriculography revealed multivessel coronary artery disease and a large apical aneurysm. Echocardiography and gated SPECT studies were performed for further evaluation of ischemia and assessment of left ventricular function. Gated SPECT and echocardiography failed to detect a large apical aneurysm due to a hyperdynamic left ventricular wall at the neck of the aneurysm. This case demonstrates the importance of using multiple imaging modalities in the evaluation of ventricular function in the setting of coronary artery disease.     

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。     

Usefulness of stress gated technetium-99m single photon emission computed tomographic myocardial perfusion imaging for the prediction of cardiac death in patients with moderate to severe left ventricular systolic dysfunction and suspected coronary artery disease

Although stress gated technetium-99m single-photon emission computed tomographic (SPECT) myocardial perfusion imaging (MPI) is useful in differentiating ischemic from nonischemic cardiomyopathy, its prognostic usefulness in this patient population is not well understood. Consecutive unique patients with suspected coronary artery disease who, for clinical indications, underwent technetium-99m rest and stress MPI demonstrating ejection fractions ≤40% by gated SPECT imaging were retrospectively identified. In addition to prescan variables, previously defined cutoffs for gated SPECT parameters using visual and standard 17-segment semiquantitative scoring were applied and related to the occurrence of cardiac death up to 5 years after MPI. Of the 475 patients fulfilling criteria for study inclusion, follow-up was complete in 444 (93%) over 3.7 ± 1.6 years. Of 393 patients without subsequent early (≤60 days) coronary revascularization, cardiac death occurred in 64 (16%). The summed stress score, an MPI measure of the extent and severity of coronary artery disease that also accounts for the ischemic burden, was the gated SPECT parameter most related to cardiac death with Kaplan-Meier 5-year cardiac death-free survival of 85.6% and 67.3% in patients with summed stress scores ≤8 and >8, respectively (p <0.001). In multivariate Cox regression analysis, a summed stress score >8 independently contributed to cardiac death (adjusted hazard ratio 2.20, 95% confidence interval 1.34 to 3.61), and its addition to the model significantly increased the global chi-square value over prescan variables (from 32.46 to 41.67, p = 0.002). In conclusion, stress MPI data from gated technetium-99m SPECT scans are useful for the prediction of cardiac death in patients with moderate to severe left ventricular systolic dysfunction in whom there is suspicion of underlying coronary artery disease.     

Identification of severe and extensive coronary artery disease by postexercise regional wall motion abnormalities in Tc-99m sestamibi gated single-photon emission computed tomography

Postexercise wall motion abnormality (WMA) in patients with normal resting myocardial perfusion may represent prolonged postischemic stunning, and may be related to the presence of severe angiographic coronary artery disease (CAD). This study assesses the diagnostic value of postexercise WMA by technetium-99m (Tc-99m) sestamibi gated single-photon emission computed tomography (SPECT) in patients with normal resting perfusion. Ninety-nine patients underwent exercise gated Tc-99m sestamibi/resting thallium-201 SPECT and coronary angiography within 90 days of nuclear testing. All patients had normal perfusion at rest. Multivariate logistic regression analysis demonstrated an incremental value of wall motion and perfusion over perfusion data alone in identifying severe and extensive CAD. Sensitivity for identifying any severely stenosed coronary artery by WMA was significantly higher than by severe perfusion defect (78% vs 49%, p <0.0001). Overall specificities of severe perfusion defect and WMA were 91% and 85%, respectively (p = NS). Thus, postexercise WMA detected by gated Tc-99m sestamibi SPECT in patients with normal resting perfusion is a sensitive marker of severe and extensive CAD.     

Value of Gating of Technetium-99m Sestamibi Single-Photon Emission Computed Tomographic Imaging

Objectives. The purpose of this study was to determine how frequently and for what reasons the addition of electrocardiographically gated technetium-99m (Tc-99m) sestamibi single-photon emission computed tomographic (SPECT) images add value to nongated SPECT perfusion images.

Background. Electrocardiographic gating of Tc-99m sestamibi SPECT images permits assessment of regional and global left ventricular function and may assist in differentiating attenuation artifacts from myocardial scar.

Methods. A total of 285 consecutive patients (143 women and 142 men; mean age 57.6 ± 11.5 years) underwent gated SPECT Tc-99m sestamibi imaging (212 with exercise, 63 with dipyridamole and 10 with dobutamine). The conventional stress and rest tomograms were interpreted first by means of a 14-segment scoring system, and then the studies were reinterpreted while the gated images were viewed.

Results. In the total group of 285 patients, the number of “borderline” interpretations was reduced from 89 to 29. In the 137 patients with a ≤10% pretest likelihood of coronary artery disease, the addition of gated images added significantly to the percentage of interpretations that were designated “normal” (74% [101 of 137] vs. 93% [127 of 137], p < 0.0001), due to a reduction in borderline normal and borderline abnormal readings. In 49 patients with a previous infarction or recent angiography with ≥70% stenosis, or both, the addition of gated images changed the percentage of “abnormal” scan interpretations from 78% (38 of 49) to 92% (45 of 49). This result was not significant (p = 0.09, two-tailed), but the trend was toward a greater number of unequivocal abnormal interpretations in this subgroup.

Conclusions. The addition of electrocardiographically gated Tc-99m sestamibi SPECT images to the reading of stress and rest perfusion images alone resulted in shifting the final scan interpretations to a more normal designation in patients with a low pretest likelihood of coronary artery disease, and to more abnormal defects consistent with coronary artery disease in patients with known coronary artery disease. The number of “borderline normal” and “borderline abnormal” interpretations are significantly reduced when gated SPECT images are interpreted simultaneously with stress and rest perfusion images.     

Hybrid SPECT-CT: Integration of CT coronary artery calcium scoring and angiography with myocardial perfusion

A natural extension of current imaging paradigms for diagnosing coronary artery disease may well be the integration of CT with myocardial perfusion single-photon CT (SPECT). Although there is a wealth of clinical information regarding the utility of SPECT, the value of CT in the cardiology arena has only recently been explored. CT has the advantage of detecting coronary atherosclerosis at its earliest stages, allowing initiation of appropriate therapeutic measures well before development of obstructive coronary artery disease. However, SPECT can clarify the anatomic findings of CT based on a functional assessment of myocardial blood flow, thereby guiding management decisions. Hybrid imaging with SPECT and CT angiography may prove important from a diagnostic and therapeutic view point in several clinical scenarios, and it is likely that over the next decade fusion imaging may more precisely tailor therapy, reduce healthcare costs, and improve patient outcome.