Rest Tc-99m Sestamibi Research Articles

Reassessing the clinical significance of electrocardiographically unrecognized myocardial infarctions: Radionuclide infarct size and its impact on long-term prognosis.

Silent or unrecognized myocardial infarction (UMI) diagnosed by surveillance electrocardiography (ECG) carries similarly poor prognosis as recognized MI (RMI) for poorly understood reasons. This study included 5430 consecutive patients who presented to the nuclear laboratory and underwent 2-day stress and rest Tc-99m sestamibi and ECG studies between March 1991 and June 1999. UMI was diagnosed if ECG showed Q-wave MI in the absence of a history of RMI. We measured infarct size (% defect size as compared with the entire left ventricular sestamibi uptake), ejection fraction (EF, %), and summed difference score (SDS, sestamibi uptake by myocardium in stress minus sestamibi uptake in rest images as a marker of ischemia). Survival was determined by follow-up survey (median 6 years). We identified 346 UMIs, 628 RMIs, and 4456 subjects without MI (No MI). As compared with RMI, UMI patients had lesser abnormalities on nuclear scans (p < .0001 for all), including smaller infarct size (5.7% vs. 12.2%), higher EF (58% vs. 53%), and lesser ischemia (SDS; 3.9% vs. 2.7%). UMI prognosis was as poor as that of RMI (annual mortality rate 4.7% vs. 4.8% with No MI rate of 2.9%; p < .001 for all comparisons), and this persisted after multivariate analysis. Infarct size quantification successfully risk-stratified ECG-UMI patients, but UMI patients continued to predict mortality even if the infarct size was 0%. Although UMI patients have lesser abnormalities on nuclear scans, ECG-based UMI continues to independently predict mortality, indicating the continuing relevance of ECG in clinical practice.

Development and validation of a phase analysis tool to measure interventricular mechanical dyssynchrony from gated SPECT MPI

ObjectivesThe purpose of this study is to develop a right-ventricular (RV) phase analysis tool which when coupled with our left ventricular (LV) phase analysis tool can provide measurement of the interventricular mechanical dyssynchrony from gated SPECT myocardial perfusion imaging (MPI), and validate the tool by electrocardiography (ECG). MethodsFor each patient, short-axis LV and RV SPECT MPI images were input into an automatic sampling algorithm to generate the 3D maximal count circumferential profiles for both LV and RV in each cardiac frame. Subsequently, the samples of LV and RV were separately used by our phase analysis tool based on the first-harmonic Fourier approximation to calculate the contraction onset for each sample. The difference between contraction onsets of the middle LV free wall and middle LV septal wall represented the LV contraction delay; the difference between contraction onsets of the middle RV free wall and middle RV septal wall represented the RV contraction delay. The difference between the LV and RV contraction delays represented the interventricular contraction delay, which was compared with the interventricular conduction delay classified by ECG to validate the concordance of interventricular mechanical and electrical dyssynchrony. Sixty-one bundle branch block (BBB) patients with ischemic-dilated cardiomyopathy (26, 42.6%) or non-ischemic-dilated cardiomyopathy (35, 57.4%), who underwent 12-lead surface ECG and gated resting Tc-99m sestamibi SPECT, were retrospectively analyzed in this study. ResultsIn the 30 patients with left bundle branch block (LBBB) by ECG, there were 27 patients whose LV contracted later than the RV according to SPECT; and in the 31 patients with right bundle branch block (RBBB) by ECG, there were 26 patients whose LV contracted earlier than the RV according to SPECT. In total, an agreement rate of 86.9% (53 of 61) was achieved between SPECT and ECG. The Kappa agreement rate was 73.8% (95% confidence interval 0.57-0.91). ConclusionThe preliminary results showed promise for the measurement of interventricular mechanical dyssynchrony in BBB patients with dilated cardiomyopathy using our phase analysis tool.

Abstract 5818: Stress Thallium-201/Rest Tc-99m Sequential Dual Isotope High-Speed Myocardial Perfusion Imaging

Recent advances in gamma camera technology are providing opportunities for novel high-speed myocardial perfusion imaging (HS-MPI) protocols. We aimed to develop and evaluate a stress thallium-201 (Tl-201) and rest Tc-99m sestamibi or tetrofosmin imaging protocol that could reduce imaging time and radiation burden. Methods: We studied 410 consecutive patients undergoing exercise or pharmacologic low-dose stress Tl-201 HS-MPI (4 min/acquisition) in the semi-upright and supine positions (D-SPECT, Spectrum-Dynamics) followed by rest Tc-99m sestamibi (n= 139) or tetrofosmin (n= 271) with immediate post-injection rest imaging. Of 330 patients with no known coronary artery disease (CAD), 29 patients also underwent invasive coronary angiography (ICA) or coronary computed tomography angiography (CCTA) within a three month period and 36 had a &lt; 5% pre-test likelihood of CAD (LLk). Despite low injected doses [Tl-201 (2.2± 0.3 mCi) and Tc-99m sestamibi or tetrofosmin (8.9± 2.4 mCi), the 3 acquisition MPI protocol (2 stress/1 rest) was accomplished &lt; 20 minutes. The quality of stress and resting image was good to excellent in &gt;96% of cases; importantly, no or minor extracardiac activity was seen on 99% of stress and 93% of rest images. HS-MPI was nondiagnostic or uninterpretable in only 2/410 patients. In the 29 patients with CCTA or ICA, the sensitivity and specificity for the detection of ≥70% stenosis were 73% and 89%, respectively, and in 15 patients with ICA, the sensitivity was 89%. The normalcy rate in the LLk group was 100%. A fast stress Tl-201/rest Tc-99m HS-MPI protocol offers promise as a time-efficient, low radiation dose method, in which the superior qualities of Tl-201 for stress imaging and of Tc-99m agents for rest imaging can be utilized.

Normal limits for left ventricular ejection fraction and volumes determined by gated single photon emission computed tomography – a comparison between two quantification methods

To compare gender-related normal limits for left ventricular (LV) ejection fraction (EF), end-diastolic and end-systolic volumes (EDV and ESV), obtained using two myocardial perfusion-gated single photon emission computed tomography (SPECT) quantification methods. A total of 185 patients were retrospectively selected from a consecutive series of patients examined for coronary artery disease (CAD) or for management of known CAD. Patients were included in the study group if they had normal or probably normal results with stress and rest perfusion imaging and if the combined interpretation of perfusion studies and gated rest studies showed no signs or suspicion of myocardial infarction. The gated SPECT studies were performed using a 2-day stress/gated rest Tc-99m sestamibi protocol. All patient studies were processed using CAFU and quantitative-gated SPECT (QGS), the two software packages for quantification of gated SPECT images. The lower normal limits for EF were higher for CAFU compared with QGS for both women (59% versus 53%) and men (54% versus 47%). The upper normal limits for EDV were also higher for CAFU compared with QGS for both women (133 versus 107 ml) and men (182 versus 161 ml). The differences between the software packages were small for ESV (women 44 versus 44 ml; men 69 versus 74 ml). Gender-specific normal limits need to be applied for LV EF and volumes determined by gated SPECT. Separate criteria for abnormal LV EF and EDV need to be used for women and men depending on the software package used.

Abstract 1772: Electrocardiographic Unrecognized Myocardial Infarction Risk Stratification: Quantitated SPECT Infarct Size Predicts Mortality Independent of Clinical and Exercise Test Variables

Background : Unrecognized myocardial infarction (UMI), as diagnosed by surveillance electrocardiography (ECG), has the same poor prognosis as recognized (RMI), independent of ejection fraction or ischemia. The value of post UMI risk stratification by infarct size is unknown. Methods : The study group consisted of 5430 patients who underwent 2 day stress (exercise n = 191, pharmacologic n = 155) and rest Tc-99m sestamibi SPECT studies. UMI was diagnosed if ECG showed Q wave MI in the absence of history of MI. SPECT infarct size was quantitated based on a 60% of peak counts threshold method and was expressed as a percentage of the left ventricle (% LV). The association between infarct size and mortality was adjusted for clinical and exercise test prognostic scoring systems. Results : The population consisted of 346 UMI, 628 RMI, and 4456 patients without MI (No MI). Compared to No MI, mortality risk was increased in UMI (RR 1.7, 95% CI 1.6–1.9; p &lt; 0.001) and RMI (RR 1.6, 95% CI 1.4–1.9; p &lt; 0.001) patients. In the UMI group, infarct size was significantly associated with mortality ( p &lt; 0.001), which persisted after adjustment for Mayo prognostic score alone (available in all patients) ( p &lt; 0.001) and for Mayo prognostic score, Framingham risk score, and Duke treadmill score (data available in 137 patients) ( p &lt; 0.001). For every 10% LV increase in infarct size, mortality risk increased 30% (RR = 1.3, 95% CI 1.2–1.5) (see figure ). Conclusions: In patients with UMI, larger quantitated SPECT infarct size predicts increased mortality independent of clinical and exercise test prognostic scoring systems. This finding supports the use of infarct size imaging for risk stratification of UMI patients.

Gated Myocardial Perfusion SPECT in Patients With a Small Heart: Effect of Zooming and Filtering

Abstract: Underestimation of left ventricular end-diastolic volume (EDV), end-systolic volume (ESV) and overestimation of ejection fraction (LVEF) in patients with a small heart is a problem with the gated myocardial perfusion SPECT (GSPECT). Thirty patients with a small heart underwent rest Tc-99m sestamibi GSPECT using acquisition zooms of 1.45 and 1.78 consecutively. After reconstruction by filtered back-projection using different cut-off frequencies of Butterworth filter, LVEF, EDV and ESV were computed using a quantitative gated SPECT (QGS) program. Increasing in zooming or filter cut-off frequency resulted in higher EDV and ESV but lower LVEF. Differences in LVEF between 2 acquisition zooms were decreased by sharper cut-off frequencies. A higher zooming and/or a sharper filter might be suggested for quantitative GSPECT in patients with a small heart.

Predictors of differences in left ventricular ejection fraction and volumes determined by quantitative gated rest and post-stress Tc-99m sestamibi SPECT

Predictors of differences in left ventricular ejection fraction and volumes determined by quantitative gated rest and post-stress Tc-99m sestamibi SPECT

Influence of infarct-zone viability detected by rest Tc-99m sestamibi gated SPECT on left ventricular remodeling after acute myocardial infarction treated by percutaneous transluminal coronary angioplasty in the acute phase

The purpose of this study was to assess the value of technetium 99m sestamibi gated single photon emission computed tomography (SPECT) in predicting the evolution of left ventricular volumes in patients treated successfully in the acute phase of a myocardial infarction (MI). Twenty-nine patients with acute MI and early percutaneous transluminal coronary angioplasty (PTCA) were included in this study. A rest Tc-99m sestamibi electrocardiography (ECG)-gated SPECT study was performed 21 +/- 5 days after PTCA. The myocardial perfusion index was calculated by use of a semiautomatic sectorial analysis. All patients had contrast ventriculography performed during the acute phase and 6 months later. The patients were separated into two groups according to the absence (group I, n = 21) or presence (group II, n = 8) of end-systolic enlargement. The perfusion index in the infarct sectors was -2.29 +/- 2.90 SD in group I and -6.40 +/- 2.85 SD in group II ( P < .01). With a cutoff value of -2.46 SD, the sensitivity and specificity of Tc-99m sestamibi SPECT for the prediction of end-systolic volume enlargement were 100% and 62%, respectively. When the functional data from ECG-gated acquisitions were added, specificity increased to 86%. Despite successful PTCA in the acute phase of MI, an increase in end-systolic volume was observed at 6 months in 28% of patients. Tc-99m sestamibi ECG-gated SPECT performed 3 weeks after the acute phase could predict this enlargement with a high accuracy.

Predictors of differences in left ventricular ejection fraction and volumes determined by quantitative gated rest and post-stress Tc-99m sestamibi SPECT

Background: Quantitative gated SPECT (QGS) is useful in evaluating left ventricular ejection fraction (LVEF), end systolic volume (ESV), and end diastolic volume (EDV). Less is known regarding factors potentially associated with differences in LVEF and volumes obtained from QGS at rest and post-stress. Methods: Using a 2-day protocol, SPECT data was obtained at rest and post-stress with high dose (25 mCi) Tc-99m sestamibi bolus. LVEF, ESV, and EDV were derived from automated Cedars-Sinai QGS software. Of 100 patients prospectively studied, 92 studies were technically adequate. Delta LVEF was defined as QGS rest EF minus QGS post-stress LVEF. Delta ESV and EDV were similarly defined. Results: (See table). LVEF, ESV, and EDV rest and post-stress were highly correlated. LVEF and EDV were higher at rest than post-stress. Summed difference score (SDS) >0 was significantly associated with increased delta LVEF (p=0.02). Mean LVEF post-stress in ischemic patients was 55.0% vs 61.1% in nonischemic patients (p=0.01). SDS=0 was associated with increased delta EDV (p<0.001). Mean post-stress EDV in ischemic patients was 94.4 cc vs 80.1 cc in nonischemic patients (p<0.01). SDS=0 was associated with increased delta ESV (p=0.002). Mean post-stress ESV in ischemic patients was 43.4 cc vs 32.1 cc in nonischemic patients (p<0.01). Conclusion: QGS post-stress is highly correlated with QGS rest for LVEF, EDV, and ESV. The mean QGS rest LVEF and rest EDV are significantly higher than post-stress LVEF and stress EDV. Ischemia is associated with lower QGS post-stress LVEF which may represent post-stress ischemic LV dilatation with increased post-stress ESV and EDV. Rest Post-Stress r p Mean delta p LVEF (%) 61.1 59.2 0.89 <0.001 1.9 <0.001 EDV (cc) 88.1 84.8 0.88 <0.001 3.3 <0.01 ESV (cc) 35.4 35.8 0.93 <0.001 −0.4 NS

Comparison of extent and severity of quantitative perfusion defects on rest Tl-201 and rest Tc-99m sestamibi myocardial perfusion SPECT

Background: Rest Tl-201 (Tl) myocardial perfusion SPECT (MPS) has been widely used alone or in dual isotope MPS, but the direct comparison of quantitative perfusion defect (PD) on rest Tl and rest sestamibi (MIBI) MPS has not been evaluated in depth. Methods: 162 pts in a randomized clinical trial with known or suspected CAD ( ≥4/20 segments with reversible defects, age 40–76, 34 F) underwent same day rest Tl followed immediately by rest MIBI injection and MPS 1 hr later. The same protocol was repeated in 56 pts of the placebo group (with no clinical changes or coronary interventions) at day 60. Reconstruction using Butterworth filtered backprojection, cutoff /order 0.55 / 5.00 for MIBI and 0.50 / 10.00 for Tl, sex and isotope specific normal limits were used. PD extent (% of pixels abnormal) and severity (mean number of standard deviations by which counts of abnormal pixels fell below normal profile) were determined by QPS. Correlation and regression analysis were performed. Results: The linear correlation between rest Tl and rest MIBI showed high agreement as follows: N = 162 R 2 Rt MSE Regression Extent MIBI-TI 0.93;*> 2.91 MIBI ext = 1.03 TI ext + 1.32 Severity MIBI-TI 0.90;*> 0.20 MIBI sev = 1.04 TI sev + 0.06 Repeated scans at day 60 showed similar results for MIBI and Tl agreement, and good inter scan reproducibility (MIBI day 0 vs day 60). * N = 56 R 2 Rt MSE Interscan R 2-MIBI Rt MSE Extent MIBI-TI 0.96 * 2.42 Extent 0.94 * 2.69 Severity MIBI-TI 0.92 * 0.18 Severity 0.94 * 0.16 * (p < 0.0001) Conclusion: Quantitative analysis of perfusion defect extent and severity on same day rest Tl and rest MIBI MPS shows excellent correlation which is as high as the reproducibility of day 0 vs day 60 MIBI. These findings indicate that a rest Tl / rest MIBI protocol may be useful in same day assessment of changes in myocardial perfusion with therapeutic interventions.

Centering Artifacts Manifesting As Anterior Wall Defects On Myocardial SPECT Imaging

Purpose: During cardiac SPECT acquisitions in-vitro work has shown that artifacts that may be prospectively interpreted as anterior wall defects can be caused by body centered acquisitions rather than heart centered acquisitions. The purpose of this study was to quantify the effects of center of rotation (COR) placement at the heart, or body centered circular orbits in patients. Methods: 44 patients underwent stress and rest Tc99m-Sestamibi SPECT myocardial scintigraphy using 20-30mCi (740-1070 MBq) and 8-10mCi (259-370 MBq) respectively (64 and 32 views at 30sec/view) using a Siemens Orbiter camera. All image data was evaluated by two radiologists blinded to each others readings. The raw projectional data was rated as body centered, heart centered, or in between using a nominal scale. The SPECT reconstruction data was interpreted for anterior wall defects on rest and stress images. Kappa statistic was calculated between observers and Maentel-Hentzel test for trend between number of anterior wall defects and increasing body centering in the COR of the SPECT acquisition was calculated. Results: Kappa statistics demonstrated good (>0.70) agreement between observers. Analysis demonstrated increasing number of anterior wall defects as the COR moved from heart centered to body centered with an odds ratio of 2.5 [95%CI:1.09-20] for number of anterior wall defects in body centered vs. heart centered acquisitions at rest. In particular 2 cases with anterior wall defects had less cardiac centering on the rest images than the stress images on which these defects were no longer visible. Conclusion: Increasing the distance between the COR of a SPECT acquisition and the anatomic center of the heart causes increasing anterior wall defects to be detected in vivo and may be contributing to artifacts in a daily clinical setting when using 180 degree acquisitions.

13.25 Additional implication of resting Tc-99m sestamibi imaging in patients with myocardial infarction

13.25 Additional implication of resting Tc-99m sestamibi imaging in patients with myocardial infarction

Development of a method for measuring myocardial contractility with gated myocardial SPECT and arterial tonometry

Background. Gated myocardial single photon emission computed tomography (SPECT) and radial artery applanation tonometry were used, respectively, to quantify the time-volume curve of the left ventricle and to estimate ventricular pressure wave. We developed ways of determining end-systolic elastance (Ees) with the normalized-single-beat method and tested the reproducibility of these measurements. Methods and Results. In patients with coronary artery disease (male/female = 33:2, age 66 ± 10 years, ejection fraction 22% to 77%), rest thallium-201 gated/poststress technetium-99m sestamibi gated SPECT/24-hour rest Tc-99m sestamibi gated SPECT and arterial tonometry were performed. Quantitative gated SPECT software yielded a systolic time-volume curve, and tonometrically measured radial artery pressure wave yielded central aortic pressure wave. With systolic half of pressure-volume curve, void volume (Vo) was estimated and Ees was calculated. Over 71 measurements Ees ranged from 1.7 to 5.3 and Vo from −4 to 200 mL. Ejection duration, other indexes of central pressure waveform, end-diastolic volume, end-systolic volume, and ejection fraction were reproducible. The reproducibility of Vo was excellent ( r = 0.97). Ees at rest (n = 15) showed fair reproducibility between Tc-99m-sestamibi and Tl-201 SPECT (r = 0.51). Conclusion. With gated myocardial SPECT, a noninvasive method of quantifying myocardial global contractility was developed. Reproducibility of this measurement was sufficient for use in clinical routine. Ees measured by this method warrants validation by invasively measured Ees.

Resting sestamibi imaging for the prognosis of low-risk chest pain.

To assess the prognostic value of resting Tc-99m sestamibi scanning for adverse cardiac events (ACEs) in ED chest pain patients with a low probability of acute cardiac ischemia (ACI). Sixty-nine consenting, hemodynamically stable patients with chest pain and a nondiagnostic electrocardiogram received an injection of 25 mCi of sestamibi during or within two hours of active pain. Scans were interpreted locally by a nuclear cardiologist or radiologist. Interrater reliability was assessed. ACEs of myocardial infarction (MI), death, or revascularization were assessed during the index hospitalization and over a one-year follow-up period. For ACEs, rest scanning with sestamibi had a sensitivity of 71% (95% CI = 0.33 to 0.97), a specificity of 92% (95% CI = 0.82 to 0.97), and an accuracy of 90% (95% CI = 0.87 to 0.99). The positive predictive value was 50% (95% CI = 0.19 to 0.82) and the negative predictive value was 97% (95% CI = 0.87 to 0.98). Sestamibi scanning was highly discriminating, with 62% of patients with positive scans but only 3% with negative scans having ACEs (p<0.001, log rank test). In patients with low-risk chest pain, sestamibi scanning has good specificity and moderate sensitivity for ACEs over a 12-month period.

Interpretive reproducibility of stress Tc-99m sestamibi tomographic myocardial perfusion imaging

Background: Observer variability has been shown with interpretation of planar thallium-201 images. The interpretive reproducibility of technetium-99m sestamibi tomographic imaging is unknown. This study evaluated the interpretive reproducibility of interpretable Tc-99m sestamibi tomographic images among nuclear cardiologists with a wide range of training and experience. Methods: Three experienced readers (EX) and 3 less-experienced readers (LEX) interpreted 138 exercise and rest Tc-99m sestamibi tomographic images (101 were abnormal in patients with coronary artery disease [CAD], 37 were normal in patients with <5% likelihood of CAD) twice in random sequence without clinical data. Images of good to excellent quality were randomly selected from a database at 2 nuclear cardiology laboratories. Intraobserver and interobserver agreement for global, left anterior descending (LAD) territory, non-LAD first (normal/abnormal) and second (normal/fixed/reversible) order, and defect extent (normal/single-vessel CAD/multi-vessel CAD) were assessed with percent agreement and Cohen's kappa κ statistic. Results: With regard to intraobserver agreement, first and second order ranged from 87% to 94% and 80% to 90% for global, 82% to 96% and 78% to 95% for LAD, and 88% to 91% and 80% to 90% for non-LAD, respectively. Defect extent ranged from 75% to 90%. There were no differences between EX and LEX for global and non-LAD first and second order, LAD first order, and defect extent. LAD second order was 93% for EX compared with 88% ( P .015) for LEX. With regard to interobserver agreement, first and second order ranged from 73% to 89% and 64% to 85% for global, 73% to 93% and 69% to 91% for LAD, and 76% to 88% and 68% to 84% for non-LAD, respectively. Defect extent ranged from 61% to 82%. Global first and second order ranged from 85% to 87% and 78% to 82% for EX compared with 73% to 84% and 64% to 79% for LEX. LAD first and second order ranged from 89% to 91% and 88% to 89% for EX compared with 73% to 91% and 69% to 70% for LEX. Non-LAD first and second order ranged from 82% to 86% and 76% to 77% for EX compared with 76% to 86% and 68% to 81% for LEX. Defect extent ranged from 69% to 75% for EX compared with 59% to 77% for LEX. Conclusions: There is moderate to excellent interpretive reproducibility with stress Tc-99m sestamibi SPECT imaging among nuclear cardiologists with a wide range of training and experience.

Assessment of regional and global left ventricular function by reinjection Tl-201 and rest Tc-99m sestamibi ECG-gated SPECT: Comparison with three-dimensional magnetic resonance imaging

OBJECTIVESThe purpose of this study was to test the ability of reinjection thallium-201 and rest technetium-99m sestamibi ECG (electrocardiographic)-gated SPECT (i.e., reinjection-g-SPECT [single-photon emission computed tomography] and MIBI-g-SPECT) to determine regional and global functional parameters.BACKGROUNDThe ECG-gated perfusion SPECT was reported to provide accurate left ventricular ejection fraction (LVEF) using an automated algorithm. We hypothesized that other various functional data may be obtained using reinjection-g-SPECT and MIBI-g-SPECT.METHODSReinjection-g-SPECT, MIBI-g-SPECT, and three-dimensional magnetic resonance imaging (3DMRI) were conducted in 20 patients with coronary artery disease. Regional wall motion (RWM) and wall thickening (RWT) were analyzed using semiquantitative visual scoring by each g-SPECT and 3DMRI. The left ventricular end-systolic and end-diastolic volumes (EDV, ESV) and LVEF estimated by reinjection- and MIBI-g-SPECT were compared with the results of 3DMRI.RESULTSA high degree of agreement in RWM and RWT assessment was observed between each g-SPECT and 3DMRI (kappa >.70, p < .001). The LVEF values by reinjection- and MIBI-g-SPECT correlated and agreed well with those by 3DMRI (reinjection: r = .92, SEE = 5.9%, SD of differences = 5.7%; sestamibi: r = .94, SEE = 4.4%, SD of differences = 5.1%). The same also pertained to EDV (reinjection: r = .85, SEE = 18.7 ml, SD of differences = 18.4 ml; sestamibi: r = .92, SEE = 13.1 ml, SD of differences = 13.0 ml) and ESV (reinjection: r = .94, SEE = 10.3 ml, SD of differences = 10.3 ml; sestamibi: r = .97, SEE = 6.7 ml [p < .05 vs. reinjection by F test], SD of differences = 6.6 ml [p < .05 vs. reinjection by F test]).CONCLUSIONSReinjection- and MIBI-g-SPECT provide clinically satisfactory various functional data. These functional data in combination with the perfusion information will improve diagnostic and prognostic accuracy without an increase in cost or the radiation dose to the patients.

Influence of a platelet GPIIb/IIIa receptor antagonist on myocardial hypoperfusion during rotational atherectomy as assessed by myocardial Tc-99m sestamibi scintigraphy

OBJECTIVESThis study evaluated the effect of the glycoprotein IIb/IIIa (GPIIb/IIIa) antagonist abciximab on myocardial hypoperfusion during percutaneous transluminal rotational atherectomy (PTRA).BACKGROUNDPTRA may cause transient ischemia and periprocedural myocardial injury. A platelet-dependent risk of non-Q-wave infarctions after directional atherectomy has been described. The role of platelets for the incidence and severity of myocardial hypoperfusion during PTRA is unknown.METHODSSeventy-five consecutive patients with complex lesions were studied using resting Tc-99m sestamibi single-photon emission computed tomography prior to PTRA, during, and 2 days after the procedure. The last 30 patients received periprocedural abciximab (group A) and their results were compared to the remaining 45 patients (group B). For semiquantitative analysis, myocardial perfusion in 24 left ventricular regions was expressed as percentage of maximal sestamibi uptake.RESULTSBaseline characteristics did not differ between the groups. Transient perfusion defects were observed in 39/45 (87%) patients of group B, but only in 10/30 (33%) patients of group A (p < 0.001). Perfusion was significantly reduced during PTRA in 3.3 ± 2.5 regions in group B compared to 1.4 ± 2.5 regions in group A (p < 0.01). Perfusion in the region with maximal reduction during PTRA in groups B and A was 76 ± 15% and 76 ± 15% at baseline, decreased to 56 ± 16% (p < 0.001) and 67 ± 14%, respectively, during PTRA (p < 0.01 A vs. B), and returned to 76 ± 15% and 80 ± 13%, respectively, after PTRA. Nine patients in group B (20%) and two patients in group A (7%) had mild creatine kinase and/or troponin t elevations (p = 0.18). Patients with elevated enzymes had larger perfusion defects than did patients without myocardial injury (4.2 ± 2.7 vs. 2.3 ± 2.5 regions, p < 0.05).CONCLUSIONSThese data indicate that GPIIb/IIIa blockade reduces incidence, extent and severity of transient hypoperfusion during PTRA. Thus, platelet aggregation may play an important role for PTRA-induced hypoperfusion.

Combined Tc-99m sestamibi first-pass radionuclide angiography and cardiac SPECT imaging during arbutamine infusion delivered by a computerized closed-loop system.

This study evaluated the feasibility, hemodynamic responses, and relation of combined Tc-99m sestamibi SPECT imaging and first-pass radionuclide angiography during the infusion of a new beta agonist arbutamine. Arbutamine was administered to 15 patients and constantly adjusted by a closed-loop computerized system. Rest and arbutamine Tc-99m sestamibi radionuclide angiography was performed with a multicrystal gamma camera followed by SPECT imaging with a rotating triple-head, single-crystal gamma camera. The mean differences (paired t-test) between rest and arbutamine studies for heart rate (HR), end-diastolic volume (EDV), stroke volume (SV), cardiac output (CO), and ejection fraction (EF) were as follows: 55 bpm for HR (P < 0.001), 5 ml for EDV (P=ns), 7.5 ml for SV (P=0.04), 4.4 l/min for CO (P < 0.001), and 6.4% for EF (P < 0.001), respectively. The results of SPECT studies were abnormal in six patients and normal in nine. Findings of radionuclide angiography were normal in 12 patients and abnormal in three. Interpretation of the perfusion and functional studies were concordant in 10 and discordant in five patients. Simultaneous cardiac radionuclide angiography and SPECT imaging are feasible during arbutamine infusion. This potent beta agonist increases cardiac output through a chronotropic effect with no significant changes in EDV. The discordance in SPECT and radionuclide angiography results may represent incremental diagnostic and prognostic information provided by both studies.

A comparison of gated rest Tc-99m sestamibi scintigraphy and echo-cardiography in the assessment of acute chest pain

A comparison of gated rest Tc-99m sestamibi scintigraphy and echo-cardiography in the assessment of acute chest pain

Significance of rest technetium-99m sestamibi imaging for the prediction of improvement of left ventricular dysfunction after Q wave myocardial infarction: importance of infarct location adjusted thresholds.

The value of rest technetium-99m (Tc-99m) sestamibi scintigraphy under oral nitrate medication to predict myocardial viability was examined in patients with chronic infarcts. The value of rest Tc-99m sestamibi to predict viability in infarct regions has not been fully established because significant underestimation of viability, especially in the inferior myocardial wall, has been reported. Forty patients with Q wave myocardial infarction underwent Tc-99m sestamibi single-photon emission computed tomography under nitrate medication before revascularization of the infarct-related artery. Wall motion was quantified from paired angiograms before and 4 months after revascularization. Tracer uptake was quantified in the central infarct region identified on the angiogram. The average Tc-99m sestamibi uptake in the central infarct region of patients with anterior infarcts and improvement of left ventricular function was significantly higher (68+/-12%, mean+/-SD) than in patients without improvement of function (40+/-14%, p < 0.02). The average Tc-99m sestamibi uptake in the central infarct region of patients with improvement of function and inferior infarcts was significantly lower (43+/-7%) than in patients with anterior infarcts (68+/-12%, p < 0.003), but was significantly higher than in patients with inferior infarction and no improvement of function (31+/-7%, p < 0.02). Using an infarct location adjusted optimal threshold (50% for anterior infarcts, 35% for inferior infarcts), Tc-99m sestamibi had a positive predictive value of 90% and a negative predictive value of 91% for improvement of left ventricular function. Quantitative rest Tc-99m sestamibi scintigraphy after oral nitrates reliably predicts improvement of left ventricular function after revascularization if infarct location adjusted thresholds are used.