Impact of ischemia on left ventricular dyssynchrony by phase analysis of gated single photon emission computed tomography myocardial perfusion imaging

Background

There is increasing awareness of the value of phase analysis of gated tomographic myocardial perfusion imaging in assessing left ventricular (LV) dyssynchrony. A concern repeatedly raised in many studies is whether reversible defects in the stress images “ischemia” could affect the phase-derived standard deviation and bandwidth, the two commonly used dyssynchrony indices. We hypothesized that the stress and rest images should provide comparable information because the images are acquired 1 hour after the tracer injection.

Methods and Results

We studied two groups of patients with normal LV ejection fraction and no fixed perfusion defects. In group-1 (N = 20), the patients had reversible perfusion defects involving > 10% of the LV myocardium and in group-2 (N = 20), the patients had normal images. All patients underwent stress/rest-gated single photon emission computed tomography sestamibi imaging (the stress study was acquired with the lower dose) between January and March 2010. Patients with left bundle branch block or ventricular pacing were excluded. The patients in group-1 had a mean age of 61 ± 9 years, 65% were men, 75% Caucasians, and 70% had known prior coronary artery disease. The size of the reversible perfusion defect was 20 ± 13% (range 11%-50%) of the LV myocardium. The rest and stress phase-derived standard deviation (16 ± 6° vs 18 ± 8° and 16 ± 7° vs. 19 ± 6°) and the rest and stress bandwidth (42 ± 14° vs 46 ± 16° and 45 ± 17° vs 52 ± 12°), respectively, (P = NS for all) were similar in the two groups. The change (stress–rest) in standard deviation and bandwidth in groups 1 and 2 were not statistically significant (0.2 ± 3.1° vs 1.4 ± 4.7°, and 2 ± 13° vs 5 ± 13°, respectively, P = NS). There was no significant change from rest to stress in the standard deviation and the bandwidth in group-1 (P = .8 and .4, respectively) and group-2 (P = .2 and .08, respectively). There was no correlation between the size of the reversible perfusion defect and the change in phase standard deviation or bandwidth (r = 0.07 and 0.12, respectively, P = NS).

Conclusions

The presence of even a large reversible perfusion defect does not alter the indices of mechanical dyssynchrony by phase analysis. Further, comparable information is obtained whether using a low dose or a high dose of the radiotracer.     

Prognostic characterization of patients with mild coronary artery disease with myocardial perfusion single photon emission computed tomography: Validation of an outcomes-based strategy

Conclusion  The emergence of this exciting new shift in the potential application of nuclear testing, a risk-based approach permitting the indentification of patients with mild CAD not in need of aggressive treatment, permits us not only to spare patients the risk and inconvenience of additional testing but also to better manage the available resources. O'Keefe et al.²⁹ are to be commended for pointing our a means to enhance patient care and to achieve both clinical and cost-effectiveness.     

Combined exercise radionuclide angiocardiography and single photon emission computed tomography perfusion studies for assessment of coronary artery disease

Although there is widespread use of exercise thallium 201 scintigraphy and radionuclide angiocardiography in patients with coronary artery disease (CAD), little is known about the independence, concordance, or relative importance of these studies in the diagnosis, prognosis, and assessment of the outcome of therapy. The use of both tests in the same patient has been impractical because of the logistic considerations imposed by two exercise tests on separate days, and excessive radiation exposure. New technetium 99m-labeled radiopharmaceuticals with high myocardial extraction now permit the simultaneous assessment of myocardial perfusion (single photon emission computed tomography [SPECT]) and ventricular function (radionuclide angiocardiography [RNA]) during treadmill exercise (exercise tolerance test [ETT]). The ability to perform all three tests during a single exercise session offers a very attractive technique to evaluate patients with CAD. The investigators studied 86 patients with chronic CAD using the same-day perfusion and function protocol combined with treadmill exercise. The results demonstrate good concordance between myocardial perfusion and ventricular function as indicated by a significant correlation between tomographic perfusion defect size and ejection fraction (P less than .0001, R = 0.75 at rest and P less than .0001, R = 0.76 during exercise). Stepwise logistic regression was used to model ETT, RNA, and SPECT variables against the presence of one or more 60% stenoses by quantitative angiography, an end point present in 47 patients. Univariable analysis showed all three tests (ETT, RNA, and SPECT) to be significant predictors of the end points (lambda 2 = 5.1, P less than .05; lambda 2 = 12.5, P less than .001; and lambda 2 = 16.1, P less than .001, respectively). Multivariable analysis demonstrated that SPECT provided more diagnostic information than ETT and RNA (Lambda 2 = 16.1, P less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Renal abnormalities as incidental findings on myocardial single photon emission computed tomography perfusion imaging

Incidental noncardiac abnormalities are frequent in myocardial perfusion imaging studies. It is important for interpreting physicians to be aware of the spectrum of abnormalities that can be detected from these studies. This report describes four cases with polycystic kidney disease with or without liver involvement and one case with polycystic liver disease with corroborative radiological studies.     

Quantitative assessment of regional dysfunction from gated single photon emission tomography myocardial perfusion studies: a non-segmental approach.

We present a modified (non-segmental) method for quantification of regional left ventricular dysfunction using gated myocardial perfusion SPET. Gated SPET is increasingly used to obtain complementary information on local perfusion and to assess the relevance of deficits in segmental count densities (attenuation vs perfusion deficit). The non-segmental approach was motivated by a hypothetical limitation regarding the validity of commonly used methods of quantitative wall thickening (WT) analysis. These methods are all based on segmental analysis, which could cause underestimation of 'true' contractile dysfunction in perfusion defects that do not have a strict segmental distribution. SPET images gated in eight time bins 60 min after the injection of 740 MBq 99Tcm-tetrofosmin or 99Tcm-sestamibi were recorded on a triple-headed camera in 20 normal subjects and in 16 patients within 2 weeks and again 3 months after myocardial infarction. Normal limits of wall thickening, calculated from pooled wall thickening profiles obtained in normal subjects, were used to identify and quantify areas with abnormal wall thickening in patients with coronary artery disease. The method was validated against data obtained from contrast ventriculography (CVG) and tested for reproducibility. The reproducibility of the method was excellent: r = 0.98 (WTsev measure 1 = 1.03WTsev measure 2 - 0.01). The localization of wall thickening abnormalities detected by gated SPET correlated well with the localization of regions with abnormal wall motion (WM) identified by CVG. The severity of the regional myocardial dysfunction assessed by gated SPET was closely correlated with the severity of the regional myocardial dysfunction derived from CVG: r = 0.85 (WMsev = 2.55WTsev + 2.30). Furthermore, a good correlation between the total wall thickening severity score and the global left ventricular ejection fraction (LVEF) was observed early and late after myocardial infarction: r = 0.80 (WTsev = -0.4LVEF + 0.46). We conclude that quantitative analysis of regional wall thickening assessed from gated SPET myocardial perfusion scintigraphy is a reliable parameter for regional ventricular function. Categorizing wall thickening abnormalities quantitatively may be helpful in assessing small changes in regional function that may occur between sequential gated SPET images.     

Aortic knob width reflects left ventricular diastolic function assessed by gated myocardial perfusion single photon emission computed tomography in patients with normal myocardial perfusion

Background

Aortic knob width on chest radiography represents the extent of aortic dialation and tortuosity of the aortic arch. We tested the hypothesis that aortic knob width reflected left ventricular (LV) diastolic function assessed by gated myocardial perfusion single photon emission computed tomography (SPECT) in patients with normal myocardial perfusion.

Methods

One hundred and thirty patients with preserved LV ejection fraction and normal myocardial perfusion were enrolled in this study. Aortic knob width was measured along the horizontal line from the point of the lateral edge of the trachea to the left lateral wall of the aortic knob. The peak filling rate (PFR) and the one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters.

Results

There were 114 male and 16 female patients. Age ranged from 43 to 88 years (69.9?±?8.9 years). Aortic knob width ranged from 24.2 to 53.4 mm (37.6?±?5.7 mm). There was a significant correlation between age and aortic knob width (r?=?0.34, p?<?0.001). Aortic knob width was inversely correlated with both PFR (r?=??0.53, p?<?0.001) and 1/3 MFR (r?=??0.42, p?<?0.001). Multivariate linear regression analysis revealed that serum creatinine (β?=??0.16, p?=?0.045) and aortic knob width (β?=??0.45, p?<?0.001) were significant predictors of PFR, and that age (β?=??0.20, p?=?0.02) and aortic knob width (β?=??0.33, p?<?0.001) were significant predictors of 1/3 MFR.

Conclusions

Our data suggested that aortic knob width on chest radiography was a simple marker of LV diastolic function in patients with normal myocardial perfusion.

     

Influence of acquisition orbit on phase analysis of gated single photon emission computed tomography myocardial perfusion imaging for assessment of left ventricular mechanical dyssynchrony

Objective

The association between left ventricular (LV) dyssynchrony parameters, given by phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), and acquisition orbits is unclear. The aim of this study was to assess the dependence of LV dyssynchrony parameters on acquisition orbits.

Methods

Ninety-nine patients who underwent ²⁰¹Tl-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. Forty-four patients who underwent ^99mTc-tetrofosmin-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. The major hypoperfusion group with ²⁰¹Tl was divided into inferior or non-inferior wall hypoperfusion subgroups, and anteroseptal or non-anteroseptal wall hypoperfusion subgroups. Gated SPECT MPI data over a 360° acquisition orbit (360° images) and a 180° acquisition orbit (180° images) were reconstructed, and histogram bandwidth (HBW) and phase standard deviation (PSD) were compared.

Results

Between 360° and 180° images with ²⁰¹Tl, there were significant differences in HBW and PSD both globally (HBW 34.8?±?16.6 vs. 29.1?±?10.2; PSD 8.8?±?4.9 vs. 7.0?±?2.3, p?<?0.05 for both) and in the inferior wall (HBW 29.5?±?15.5 vs. 23.3?±?9.0; PSD 7.6?±?4.6 vs. 5.6?±?2.4, p?<?0.001 for both) in the major hypoperfusion group, and also in the inferior wall in all subgroups of the major hypoperfusion group. In contrast, no segment had any significant differences in HBW or PSD between 360° and 180° images with ^99mTc.

Conclusion

Differences in acquisition orbit had a significant influence on HBW and PSD with ²⁰¹Tl-gated SPECT MPI in the inferior wall in patients with major hypoperfusion myocardium.

     

SPECT在冠心病危险度分层方面的应用

应用门控心肌灌注SPECT测得的心肌灌注缺损和负荷后左室射血分数(left ventricular ejection fraction,LVEF)相结合进行危险度分层,对非致死性心肌梗死和心脏性死亡的风险进行评估以指导临床选择最佳治疗方案。对于射血分数(ejection fraction, EF) ≥ 30%,总差值分(即总负荷评分与总静息评分的差值,summed difference score, SDS)>7的中高危患者,宜进行血流重建术(revascularization);SDS为2~7的患者,若EF>50%则为低危,可给予药物治疗,而EF为30%~50%者则予药物治疗及血流重建术;若为未见心肌缺血的极低危患者,则宜药物治疗。     

Nomograms for estimating coronary artery disease prognosis with gated stress myocardial perfusion SPECT

Background  

Nomograms can be useful tools for estimating coronary artery disease (CAD) risk. We sought to devise risk-based nomograms for stress myocardial perfusion SPECT to include measures of % ischemic myocardium and left ventricular function.     

定量门控201Tl心肌显像对冠心病患者的预后价值

目的 研究定量门控201Tl心肌显像对冠心病患者预后评估及冠心病治疗方案选择的价值.方法 对84例患者进行静息和运动负荷201Tl门控心肌灌注SPECT显像,并随访(32.92±16.77)个月.对心肌灌注图像进行评分(1～4分),计算总负荷评分(SSS)、总静息评分(SRS)和总差值分(SDS=SRS-SSS)、负荷左室射血分数(EF)值和静息EF值.结果 随访中9例发生心脏事件,年发生率为3.90%.SSS、SDS、SRS以及EF值均是心脏事件的独立预测因素(P＜0.005).Cox比例风险回归分析示SSS是心脏事件的最强预测因素.根据患者的负荷后EF值、SDS等可将患者分为低危、中危和高危组.结论 应用定量门控201Tl心肌显像可以对冠心病患者进行正确的预后评估,并可指导选择治疗方案.SSS是心脏事件的最强预测因素.     

Evaluation of myocardial perfusion and function by single photon emission computed tomography

Although planar radionuclide techniques provide accurate, noninvasive measurements of myocardial perfusion and function that are of proven clinical value in the evaluation of the cardiac patient, they are limited by poor object contrast and superimposition of surrounding structures. Due to incomplete angular sampling and significant longitudinal distortion, limited angle tomography did not solve these problems. Single photon emission computed tomography (SPECT) can acquire scintillation information over very small angles of rotation and, thus, improve both object contrast and delineation of overlying or adjacent structures without distortion. The early SPECT systems were cumbersome, dependent on individual user developed software, and had extremely long acquisition and processing time. Improved camera design, new software algorithms, and the use of array processors have simplified and standardized quality control, decreased processing time, and minimized the number of user interventions. New image display formats and quantitative methods of analysis have made interpretation less cumbersome, more reliable and highly reproducible. Cardiac SPECT has been used with thallium-201 and gated blood pool imaging in both research and clinical applications and shown an improvement over planar methods of acquisition.     

Effect of tracer dose on left ventricular mechanical dyssynchrony indices by phase analysis of gated single photon emission computed tomography myocardial perfusion imaging

Background  

There are limited data on the effect of tracer dose on the reproducibility and accuracy of left ventricular (LV) mechanical dyssynchrony indices by phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).     

99Tcm-MIBI single photon emission tomography (SPET) for detecting myocardial ischaemia and necrosis in patients with significant coronary artery disease.

The ability of 99Tcm-methoxyisobutylisonitrile (MIBI) single photon emission tomography (SPET) to detect myocardial ischaemia and necrosis was assessed in 56 patients (45 male, 11 female, aged 55 +/- 5 years), with clinically recognized ischaemic heart disease (IHD). All underwent coronary angiography (CA) and left ventriculography (LV). SPET images were obtained at rest and at peak exercise (Modified Bruce) 90 min after injection of 99Tcm-MIBI (650-850 MBq). Data were acquired in 30 min over 180 degrees (from 45 degrees RAO to 45 degrees LPO) with no correction for attenuation, using a 64 x 64 matrix. The presence of persistent (P) or reversible (R) perfusion defects (PD) was then correlated to the resting and exercise ECG and to the results of CA and LV. Of the 56 patients, 34 had reversible underperfusion (RPD), 46 persistent underperfusion (PPD) and 31 had both. The occurrence of RPD correlated well with the occurrence of exercise-induced ST segment depression and/or angina (27 patients of 34 patients, 79%) and with the presence of significant coronary artery disease (CAD) (33 of 44, 73%). In 45 of 46 patients (98%) PPD corresponded to akinetic or severely hypokinetic segments (LV) usually explored by ECG leads exhibiting diagnostic Q waves (42 of 46 patients, 91%). The scan was normal both at rest and after stress in four of 11 patients with no CAD, and in two of 45 patients with CAD. Finally, an abnormal resting scan was seen in seven of 11 patients with normal coronary arteries, of whom six had regional wall motion abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproducibility of quantitative hexakis-2-methoxyisobutylisonitrile single photon emission tomography in stable coronary artery disease.

The quantification of myocardial perfusion abnormalities is necessary to allow comparison of repeated studies, especially in the evaluation of the success of medical, interventional or combined treatment in stable coronary artery disease or in evolving myocardial infarction. The purpose of this study was to assess inter-observer reproducibility of tomographic study processing using a semi-automatic quantitative programme. Technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-Sestamibi) was chosen for tomographic imaging of repeated rest-stress studies in patients with stable coronary artery disease. The quantification was performed using a modification of the Cedars polar coding and comparison with the normal data base. The perfusion defects were quantified separately for each standard perfusion area [left anterior descending (LAD), right coronary (RCA) and left circumflex (LCX) arteries] and total area of hypoperfused myocardium. The inter-observer variability for 40 tomographic studies was accomplished. The defects were the largest in the LAD perfusion area (average 19.7% of the normalized LAD supply area) with an inter-observer correlation of 0.84 for this region. The greatest variability was found for the LCX region (r = 0.55) and is attributed to a small average perfusion defect (7.1%), only 18 studies having abnormal perfusion in this area. In total, an average 14.3% of the left ventricular myocardium was significantly hypoperfused, and the inter-observer correlation was 0.87. These results show good inter-observer reproducibility using semi-automatic quantitation of perfusion defects. Careful interpretation of smaller defects in the evaluation of treatment results is advised when repeated 99mTc-Sestamibi single photon emission tomography studies are processed by more than one observer.     

Coronary angiography and thallium-201 single photon emission computed tomography in single vessel coronary artery disease

Polar presentations of selective coronary angiography and myocardial 201T1 SPECT were compared in 49 patients with single vessel disease. Twenty-six lesions were located in LAD, 8 in LCX and 15 in RCA. Perfusion defects were found within the supply area of 44 stenotic and 20 non-stenotic arteries. 201T1 SPECT detected coronary disease in 45 patients (92%) and the obstructed artery in 44 (90%). Single vessel disease was correctly indicated in 28 patients (57%) where the perfusion defects did not extend significantly outside the area supplied by the stenotic artery. Extensive perfusion defects could be explained by 'collateral steal', myocardial disease, LV aneurysm or spasm in 9 patients (18%). The absence of perfusion defect related to the stenotic artery could be explained by a moderate degree of stenosis or well developed collateral vessels in 5 patients (10%). Proximal LAD lesions resulted in larger perfusion defects than distal.