Assessment of Left Ventricular Ejection Fraction by Thallium-201 Myocardial SPECT-CT in Patients with Angina Pectoris: Comparison with 2D Echocardiography / 대한핵의학회잡지

PURPOSE: Left ventricular (LV) ejection fraction (EF) is an important parameter for assessing cardiac systolic function and predicting prognosis in patients with cardiovascular disease. The aim of this study was to evaluate the feasibility of assessing LVEF by Tl-201 hybrid myocardial single-photon emission computed tomography (SPECT)/CT using two attenuation correction methods in patients with angina pectoris.METHODS: A total of 339 patients with angina pectoris (62.8 ± 12.9 years, male:female = 206:133) were analyzed. All patients underwent Tl-201 myocardial SPECT/CT and transthoracic two-dimensional (2D) echocardiograph. We compared LVEF assessed by SPECT/CT using two attenuation correction methods: CT-based attenuation correction (CTAC) and non-attenuation correction (non-AC) methods and 2D echocardiography.RESULTS: LVEF assessed by either of the two attenuation correction techniques and 2D echocardiography showed moderate correlation in all patients with angina pectoris (r = 0.487 for CTAC and r = 0.473 for non-AC, p < 0.001). Results were similar in the subgroup of patients with perfusion abnormalities on myocardial SPECT/CT images. Overall diagnostic performances were similar for the CTAC and non-AC methods for evaluating normal and decreased LVEF by myocardial SPECT/CT.CONCLUSION: LVEF measured by the CTAC method of Tl-201-gated myocardial SPECT/CT was comparable with the conventional non-AC method in patients with angina pectoris and in the subgroup of patients with perfusion abnormality. Tl-201-gated myocardial hybrid SPECT/CT can be a reliable tool in the assessment of LVEF in clinic.

Left ventricular mass correlation between quantitative ECG-gated myocardial SPECT (QGS) and echocardiography

Left ventricular mass (LV mass) is an independent prognostic indicator of cardiovascular complications, and its regression due to therapy translates to positive clinical outcomes. Good correlation of LV mass between qualitative ECG-gated SPECT (OGS) and echocardiography has been reported, and this study aims to verify if such relationship applies in the local setting. Forty-five consecutive patients with normal myocardial perfusion SPECT and recent plain echocardiograms done in the same institution were retrospectively analyzed. Results show a significant correlation (y = 0.296x + 75.962, r = 0.491, p = 0.001) between the LV mass of the two imaging modalities, which was also observed in the TI-201  group (y= 0.256x + 80.325, r_=_0.442, p = 0.006), but not in the Tc-99m sestamibi group (y= 0.402x + 63.456, r_=_0.443, p = 0.272). The mean LV mass by OGS (122.0 ± 26.9) is significantly smaller compared with the mean LV mass by echo cardiography (155.5 ± 44.6), and the difference between the two procedures (mean ± SD: 39.7 ± 32.6, p

Usefulness of Myocardial Perfusion SPECT after Percutaneous Coronary Intervention (PCI) / 대한핵의학회잡지

As the indication of percutaneous coronary intervention (PCI) has expanded to the more difficult and complicated cases, frequent restenosis is still expected after PCI. According to AHA/ACC guideline of the present time, routine use of myocardial perfusion single photon emission tomography (SPECT) is not recommended after coronary intervention, but symptom itself or exercise EKG is not enough for the detection of restensis or for the prediction of event-free survival. In high risk and/or symptomatic subjects, direct coronary angiography is required. Myocardial perfusion SPECT could detect restenosis in 79% of the patients if performed 2 to 9 months after PCI. Reversible perfusion decrease in the myocardial perfusion SPECT is known to be the major prognostic indicator of major adverse cardiac event in PCI patients and also the prognosis is benign in the patients without reversible perfusion decrease. Though the cumulated specificity is 79% in the literature and optimal timing of myocardial perfusion SPECT is in controversy, SPECT is recommended even in asymptomatic patients at 3 to 9 months after PCI. Considering the evidences recently reported in the literature, myocardial perfusion SPECT is useful for risk stratification and detection of coronary artery restenosis requiring re-intervention in the asymptomatic patients after PCI.

Improvement in Regional Contractility of Myocardium after CABG / 대한핵의학회잡지

PURPOSE: The maximal elastance (E (max) ) of myocardium has been established as a reliable load-independent contractility index. Recently, we developed a noninvasive method to measure the regional contractility using gated myocardial SPECT and arterial tonometry data. In this study, we measured regional E (max) (rE (max) ) in the patients who underwent coronary artery bypass graft surgery (CABG), and assessed its relationship with other variables. MATERIALS AND METHODS: 21 patients (M: F=17: 4, 58+/-12 y) who underwent CABG were enrolled. (201) Tl rest/ dipyridamole stress (99m) Tc-sestamibi gated SPECT were performed before and 3 months after CABG. For 15 myocardial regions, regional time-elastance curve was obtained using the pressure data of tonometry and the volume data of gated SPECT. To investigate the coupling with myocardial function, preoperative regional E (max) was compared with regional perfusion and systolic thickening. In addition, the correlation between E (max) and viability was assessed in dysfunctional segments (thickening or=60%), E (max) was 2.65+/-1.67, while it was 1.30+/-1.24 in the segments of decreased perfusion. With regard to thickening, E (max) was 3.01+/-1.92 mmHg/mL for normal regions (thickening > or=40%), 2.40+/-1.19 mmHg/mL for mildly dysfunctional regions ( or=20%), and 1.13+/-0.89 mmHg/mL for severely dysfunctional regions (< 20%). E (max) was improved after CABG in both the viable (from 1.27+/-1.07 to 1.79+/-1.48 mmHg/mL) and non-viable segments (from 0.97+/-0.59 to 1.22+/-0.71 mmHg/mL), but there was no correlation between E (max) and thickening improvements (r=0.007). CONCLUSIONS: Preoperative regional E (max) was relatively concordant with regional perfusion and systolic thickening on gated myocardial SPECT. In dysfunctional but viable segments, E (max) was improved after CABG, but showed no correlation with thickening improvement. As a load-independent contractility index of dysfunctional myocardial segments, we suggest that the regional E (max) could be an independent parameter in the assessment of myocardial function.

Diagnosis of Coronary Artery Disease Based on Cost-effectiveness Analysis

Dlagnostic strategies for coronary artery disease are diverse and include 10 exercise EKG to coronary angiography, 20 myocardial SPECT to coronary angiography, dobutamine or exercise echocardiography to coronary angiography, and direct coronary angiography. Costeffectiveness analysis can be performed considering (1) that the cost should include the costs of the diagnostic tests themselves, the cost of notdiagnosing the patients, the final test costs on false positive patients, and the cost to treat complications and 20 that the effect should include qualityadjusted life year (QAEY) with the fraction of proper diagnosis influenced by the diagnostic performance of the initial noninvasive tests. Based on the prior costeffectiveness analysis, the pretest likelihood affected most of the costeffectiveness of a diagnostic strategy. Direct angiography was most costeffective when the pretest likelihood was high (>60%), while SPECT with or without a prior exercise EKG to angiography was most costeffective when the pretest likelihood was intermediate or low. Compared to stress echocardiography, stress myocardial SPECT was more costeffective when the likelihood was moderate or high. While the prognostic significance of negative (including falsenegative) cases was important to maintain costeffectiveness of a strategy, myocardial SPECT to coronary angiography was the most costeffective method to diagnose coronary artery disease.

Tl-201 Redistribution SPECT and N-13 Ammonia PET Images in Patients with Old Myocardial Infarction and Left Ventricular Dysfunction: Segmental Comparison and Discordance Analysis / 대한핵의학회잡지

We compared rest perfusion PET with redistribution perfusion SPECT to investigate the concordant rate between PET and SPECT images and analyze the discordant pattern. MATERIALS AND METHODS: Rest N-13 ammonia and F-18 FDG PET were performed on 18 patients with old myocardial infarction and left ventricular dysfunction whose dipyridamole - 4hr redistribution Tl-201 SPECT showed one or more severe fixed defects. Regional perfusion and metabolism were evaluated visually and quantitatively with 5-segment myocardial model. RESULTS: There were high concordant rate in uptake pattern (80/90 segments, 88.9%) and high correlation coefficient on quantitative analysis (R=0.81, p< 0.001) between redistrubution Tl-201 SPECT and N-13 ammonia PET images. Nine of 18 patients had SPECT-PET concordant pattern (Group I). Ten segments (9 in inferior wall, 1 in apex) from the remaining 9 patients showed SPECT-PET discordant pattern with abnormal Tl-201 defect and near normal N-13 ammonia uptake (Group II). The diastolic and systolic left ventricular dimensions were significantly increased in Group II compared to those of Group I. When attenuation uncorrected N-13 ammonia PET images were reconstructed in Group II, it resulted in PET images with severe inferior wall defects nearly identical to those seen in redistribution Tl-201 SPECT images. CONCLUSION: Redistribution Tl-201 SPECT images showed high concordant rate and correlation with rest N-13 ammonia PET images. Most of discordant segments had fixed thallium defects in inferior wall with nearly normal N-13 ammonia uptake, which may result from severe left ventricular dilatation and attenuation by the left hemidiaphragm and cardiac blood pool.

Development of Gated Myocardial SPECT Analysis Software and Evaluation of Left Ventricular Contraction Function / 대한핵의학회잡지

OBJECTIVES: A new software (Cardiac SPECT Analyzer: CSA) was developed for quantification of volumes and ejection fraction on gated myocardial SPECT. Volumes and ejection fraction by CSA were validated by comparing with those quantified by Quantitative Gated SPECT (QGS) software. MATERIALS AND METHODS: Gated myocardial SPECT was performed in 40 patients with ejection fraction from 15% to 85%. In 26 patients, gated myocardial SPECT was acquired again with the patients in situ. A cylinder model was used to eliminate noise semi-automatically and profile data was extracted using Gaussian fitting after smoothing. The boundary points of endo- and epicardium were found using an iterative learning algorithm. Enddiastolic (EDV) and endsystolic volumes (ESV) and ejection fraction (EF) were calculated. These values were compared with those calculated by QGS and the same gated SPECT data was repeatedly quantified by CSA and variation of the values on sequential measurements of the same patients on the repeated acquisition. RESULTS: From the 40 patient data, EF, EDV and ESV by CSA were correlated with those by QGS with the correlation coefficients of 0.97, 0.92, 0.96. Two standard deviation (SD) of EF on Bland Altman plot was 10.1%. Repeated measurements of EF, EDV, and ESV by CSA were correlated with each other with the coefficients of 0.96, 0.99, and 0.99 for EF, EDV and ESV respectively. On repeated acquisition, reproducibility was also excellent with correlation coefficients of 0.89, 0.97, 0.98, and coefficient of variation of 8.2%, 5.4mL, 8.5mL and 2SD of 10.6%, 21.2mL, and 16.4mL on Bland Altman plot for EF, EDV and ESV. CONCLUSION: We developed the software of CSA for quantification of volumes and ejection fraction on gated myocardial SPECT. Volumes and ejection fraction quantified using this software was found valid for its correctness and precision.

Nitroglycerin-Challenged Tc-99m MIBI Quantitative Gated SPECT to Predict Functional Recovery After Coronary Artery Bypass Surgery / 대한핵의학회잡지

PURPOSE: The performance of nitroglycerin-challenged Tc-99m-MIBI quantitative gated SPECT for the detection of viable myocardium was compared with rest/ 24-hour redistribution Tl-201 SPECT. MATERIALS AND METHODS: In 22 patients with coronary artery disease, rest Tl-201/ dipyridamole stress Tc-99m-MIBI gated/ 24-hour redistribution Tl-201 SPECT were performed, and gated SPECT was repeated on-site after sublingual administration of nitroglycerin (0.6 mg). Follow-up gated SPECT was done 3 months after coronary artery bypass graft surgery. For 20 segments per patient, perfusion at rest and 24-hour redistribution, and wall motion and thickening at baseline and nitroglycerin-challenged state were quantified. Quantitative viability markers were evaluated and compared; (1) rest thallium uptake, (2) thallium uptake on 24-hour redistribution SPECT, (3) systolic wall thickening at baseline, and (4) systolic wall thickening with nitroglycerin-challenge. RESULTS: Among 100 revascularized dysfunctional segments, wall motion improved in 66 segments (66%) on follow-up gated myocardial SPECT after bypass surgery. On receiver operating characteristic (ROC) curve analysis, the sensitivity and specificity of rest and 24-hour delayed redistribution Tl-201 SPECT were 79%, 44% and 82%, 44%, respectively, at the optimal cutoff value of 50% of Tl-201 uptake. The sensitivity and specificity of systolic wall thickening at baseline and nitroglycerin-challenge were 49%, 50% and 64%, 65% at the optimal cutoff value of 15% of systolic wall thickening. Area under the ROC curve of nitroglycerin-challenged systolic wall thickening was significantly larger than that of baseline systolic wall thickening (p=0.004). CONCLUSION: Nitroglycerin-challenged quantitative gated Tc-99m-MIBI SPECT was a useful method for predicting functional recovery of dysfunctional myocardium.

Gated Myocardial SPECT

The advent of gated myocardial SPECT has achieved onestop imaging in coronary artery diseases. Perfusion at rest and stress is measured and quantified using software. Myocardial contractility can be determined by quantifying the global function or regional contractility markers such as wall motion or systolic thickening. Excellent reproducibility was shown for ejection fraction and left ventricular volumes and mass. Improvement of the ejection fraction by 5% or a decrease of volumes by 10 ml can be used as criteria on a postoperative or followup scan. To achieve postoperative global improvements, an increase of systolic thickening > 15% of regional segments is needed. Even the prolonged transient stunning can be detected on gated myocardial SPECT as one gated SPECT indicates the perfusion and corn tractility of each segment. Lowdose dobutaminechallenged gated SPECT is feasible and is believed to parallel lowdose dobutamine echocardiography for determination of myocardial viability. Gated SPECT was also helpful to differentiate artifacts and for risk stratification of diabetic patients ; normal perfusion with abnormal function means a worse prognosis. Gated myocardial SPECT is mandatory if SPECT cameras have the capability of gating because it provides clinicians with information not only on diagnosis but also on prognosis, treatment strategy and risk stratification.

Development of Evaluation Method of Regional Contractility of Left Ventricle Using Gated Myocardial SPECT and Assessment of Reproducibility / 대한핵의학회잡지

PURPOSE: Regional contractility can be calculated using the regional volume change of left ventricle measured by gated myocardial SPECT image and curve of central artery pressure obtained from radial artery pressure data. In this study, a program to obtain the regional contractility was developed, and reproducibility of regional contractility measurement was assessed. MATERIALS AND METHODS: Seven patients (male: female=5: 2, 58+/-11.9 years) with coronary artery diseases underwent gated Tc-99m MIBI myocardial SPECT twice without delay between two scans. Regional volume change of left ventricle was estimated using CSA (Cardiac SPECT Analyzer) software developed in this study. Regional contractility was iteratively estimated from the time-elastance curve obtained using the time-pressure curve and regional time-volume curve. Reproducibility of regional contractility measurement assessed by comparing the contractility values measured twice from the same SPECT data and by comparing those measured from the pair of SPECT data obtained from a same patient. RESULTS: Measured regional contractility was 3.36 +/- 3.38 mmHg/mL using 15-segment model, 3.16 +/- 2.25 mmHg/mL using 7-segment model, and 3.11 +/- 2.57 mmHg/mL using 5-segment model. The harmonic average of regional contractility value was almost identical to the global contractility. Correlation coefficient of regional contractility values measured twice from the same data was greater than 0.97 for all models, and two standard deviations of contractility difference on Bland Altman plot were 1.5%, 1.0%, and 0.9% for 15-, 7-, and 5-segment models, respectively. Correlation coefficient of regional contractility values measured from the pair of SPECT data obtained from a same patient was greater than 0.95 for all models, and two standard deviations on Bland Altman plot were 2.2%, 1.0%, and 1.2%. CONCLUSION: Regional contractility of left ventricle measured using developed software in this study was reproducible. Regional contractility of left ventricle will be a new useful index for myocardial function after analysis of the clinical data.

Myocardial SPECT

This review described the diagnostic efficacy of gated myocardial SPECT and its cost-effectiveness. Normal findings on myocardial stress SPECT predict negligible hard cardiac events. This prognostic value of myocardial SPECT influences cost-effectiveness of the strategy of the diagnosis of coronary artery disease. Despite the cost of the SPECT itself, the strategy of angiography following myocardial SPECT was the most cost-effective. Gated SPECT yields information regarding myocardial contractility and help differentiate attenuation artefact. Using gated SPECT, perfusion and contraction coupling can be interpreted. The test-retest reproducibility of global and regional contractile function of gated myocardial SPECT was excellent. Gated myocardial SPECT could be used to Predict functional improvement of myocardial dysfunction and to acknowledge improvement of myocardial function. Performance of rest-24 hour delay Tl-201 SPECT for viability study was good. Rest Tl-201/gated stress Tc-99m MIBI SPECT and 24-hour delay Tl-201 SPECT is a convenient method to diagnose coronary artery disease and myocardial viability.

Effects of Scatter Correction on the Assessment of Myocardial Perfusion and Left Ventricular Function by gated Tc-99m Myocardial SPECT / 대한핵의학회잡지

PURPOSE: The purpose of this study was to evaluate the effect of scatter correction on the assessment of myocardial perfusion and left ventricular function by gated Tc-99m myocardial SPECT. MATERIALS AND METHODS: Subjects were 11 normal volunteers, 20 patients with non-cardiac chest pain and 13 patients with coronary artery diseases. We classified above 3 groups into normal and diseased groups. Scatter correction was done using dual-energy-window scatter correction method (DEW-SC). We compared acquired counts, image contrast, corrected maximum relative counts, indices of left ventricular function, extent and severity of perfusion defects calculated by 'CEqual program' between scatter non-corrected and corrected images. RESULTS: Scatter corrected studies was lower in counts by 18+/-3% than uncorrected studies, but image contrast were improved in all cases. Scatter correction using DEW-SC took 3 minutes to complete, and 512 kB memory to store. There were no significant differences among indices of left ventricular function between scatter non-corrected and corrected images. Although extents of perfusion defects were not significantly different, severity was severer in scatter corrected images. CONCLUSION: Scatter correction using DEW-SC is simple to do, and improves image contrast without changing other indices of myocardial perfusion and function.

Long-term Prognostic Value of Dipyridamole Stress Myocardial SPECT / 대한핵의학회잡지

PURPOSE: Dipyridamole stress myocardial perfusion SPECT could predict prognosis, however, long-term follow-up showed change of hazard ratio in patients with suspected coronary artery disease. We investigated how long normal SPECT could predict the benign prognosis on the long-term follow-up. MATERIALS AND METHODS: We followed up 1169 patients and divided these patients into groups in whom coronary angiography were performed and were not. Total cardiac event rate and hard event rate were predicted using clinical, angiographic and SPECT findings. Predictive values of normal and abnormal SPECT were examined using survival analysis with Mantel-Haenszel method, multivariate Cox proportional hazard model analysis and newly developed statistical method to test time-invariance of hazard rate and changing point of this rate. RESULTS: Reversible perfusion decrease on myocardial perfusion SPECT predicted higher total cardiac event rate independently and further to angiographic findings. However, myocardial SPECT showed independent but not incremental prognostic values for hard event rate. Hazard ratio of normal perfusion SPECT was changed significantly (p<0.001) and the changing point of hazard rate was 4.4 years of follow up. However, the ratio of abnormal SPECT was not. CONCLUSION: Dipyridamole stress myocardial perfusion SPECT provided independent prognostic information in patients with known and suspected coronary artery disease. Normal perfusion SPECT predicted least event rate for 4.4 years.

Influence of Gating and Attenuation-correction for Diagnostic Performance of Usual Rest/stress Myocardial Perfusion SPECT in Coronary Artery Disease / 대한핵의학회잡지

PURPOSE: Either gated myocardial perfusion SPECT or attenuation corrected SPECT can be used to improve specificity in the diagnosis of coronary artery disease. We investigated in this study whether gating or attenuation correction improved diagnostic performance of rest/stress perfusion SPECT in patients having intermediate pre-test likelihood of coronary artery disease. MATERIALS AND METHODS: Sixty-eight patients underwent rest attenuation-corrected T1-20l/dipyridamole stress gated attenuation-corrected Tc-99m-MIBI SPECT using an ADAC vertex camera (M:F=29:39, aged 59+/-12 years, coronary artery stenosis> or =70%. one vessel: 13, two vessel: 18, three vessel: 8, normal: 29). Using a five-point scale, three physicians graded the post-test likelihood of coronary artery disease for each arterial territory (1 normal, 2: possibly normal 3:equivocal, 4: possibly abnormal, 5: abnormal). Sensitivity, specificity and area under receiver-operating-characteristic curves were compared for each operator between three METHODS: (A) non-attenuation-corrected SPECT; (B) gated SPECT added to (A); and (C) attenuation-corrected SPECT added to (B). RESULTS: When grade 3 was used as the criteria for coronary artery disease, no differences in sensitivity and specificity were found between the three methods for each operator Areas under receiver- operating-characteristic curves for diagnosis of coronary artery disease revealed no differences between each modality (p>005). CONCLUSION: In patients at intermediate risk of coronary artery disease, gated SPECT and attenuation-corrected SPECT did not improve diagnostic performance.

Gender Difference of Accuracy in Detecting Coronary Artery Disease by Myocardial Perfusion SPECT / 대한핵의학회잡지

PURPOSE: Myocardial SPECT is an effective test for detecting coronary artery disease in the general population. But the diagnostic accuracy between sexes is not defined. The purpose of this study is to compare the diagnostic accuracy between males and females. MATERIALS AND METHODS: One hundred and seventy seven male and 98 female patients who underwent myocardial SPECT within 1 month of coronary angiography were studied. Myocardial SPECTs were considered abnormal if fixed or reversible perfusion defects were detected. Stenosis severity of > or = 50% luminal diameter reduction of any artery defined coronary artery disease (CAD). RESULTS: Overall sensitivity for detection of CAD was 98% in men and 97% in women (p=not significant). However, specificities, accuracies, and positive predictive values (PPV) in men and women were 49% vs 31% (p<0.05), 81% vs 57% (p<0.01), 78% vs 48% (P<0.01), respectively Diagnostic accuracies for detection of right coronary artery disease were not different in both sexes, however, accuracies for detection of left anterior descending artery disease and left circumflex artery disease were significantly lower in female (p<0.05). CONCLUSION: A significant difference of diagnostic accuracy between sexes, especially in LAD and LCx disease, was noted. Artifacts from breast attenuation might be a cause for the lower diagnostic accuracy in female.

Tc-99m Myocardial Perfusion SPECT Findings of Angina Patients Showing Normal Coronary Angiography

BACKGROUND: Tc-99m myocardial perfusion imaging agents have recently found wide spread use as detecting agents of coronary diseases. Unfortunately, false positive results are not infrequent. METHODS: We analyzed Tc-99m myocardial perfusion SPECT (Tc-SPECT) findings in angina patients showing normal coronary angiography. Seventy patients who underwent myocardial SPECT wihin one month of coronary angiography which revealed no significant stenosis were studied. RESULTS: Forty six (65.7%) patients showed perfusion defects on Tc-SPECT. Eighteen were due to soft tissue attenuation, thirteen were due to technical problems such as low count rate, six were associated with intraventricular conduction abnormalities, four with coronary spasms, three with old infarctions, and one with slow coronary flow. CONCLUSION: Photon attenuation and inadequate count rates were the main causes of false positive results on myocardial SPECT imaging with Tc-99m agents. However, pathological conditions such as conduction disturbance, coronary spasm or slow coronary flow were also associated with positive SPECT findings in patients with normal coronary angiograms.

Prediction of Improvement of Myocardial Wall Motion after Coronary Artery Bypass Surgery Using Rest T1-201/Dipyridamole Stress Gated Tc-99m-MIBI/24 Hour Delay T1-201 SPECT / 대한핵의학회잡지

PURPOSE: Using rest T1-201/dipyridamole stress Tc-99m-MIBI/24 hour T1-201 SPECT, we investigated the predictive values of the markers of the stress-rest reversibility (Rev), T1-201 rest perfusion (Rest), T1-201 24 hour redistribution (Del) and Tc-99m-MIBI gated systolic thickening (Thk) for wall motion improvement after coronary artery bypass surgery. MATERIALS AND METHODS: In 39 patients (M:F=34:5, age 58+/-8), preoperative and postoperative (3 months) SPECT were compared. 24 hour delayed SPECT was done in 16 patients having perfusion defects at rest. Perfusion or wall motion was scored from 0 to 3 (0:normal to 3:defect or dyskinesia). Wall motion was abnormal in 142 segments among 585 segments of 99 artery territories which were surgically revascularized. RESULTS: After bypass surgery, ejection fraction increased from 37.8+/-9.0% to 45.5+/-12.3% in 22 patients who had decreased ejection fraction preoperatively. Wall motion improved in 103 (72.5%) segments among 142 dysfunctional segments. Positive predictive values (PPV) of Rev, Rest, Del, and Thk were 83%, 76%, 43%, and 69% respectively. Negative predictive values (NPV) of Rev, Rest, Del, and Thk were 48%, 44%, 58%, and 21%, respectively. Rest/gated stress/delay SPECT had PPV of 74% and NPV of 46%. Though univariate logistic regression analysis revealed Rev (p=0.0008) and Rest (p=0.024) as significant predictors, stepwise multivariate test found Rev as the only good predictor (p=0.0008). CONCLUSION: Among independent predictors obtained by rest T1-201/stress gated Tc-99m-MIBI/delayed T1-201 myocardial SPECT for wall motion improvement after bypass surgery, stress-rest reversibility was the single most useful predictor.

Analysis of Aggravated Perfusion in Myocardial SPECT after Coronary Artery Bypass Surgery / 대한핵의학회잡지

Though myocardial perfusion was usually expected to improve after coronary artery bypass graft(CABG) surgery, some myocardial segments were aggravated after operation, as we compared perfusion changes on postoperative SPECT with preoperative ones. In this study, we evaluated perfusion changes after operation in rest and stress myocardial SPCET in 44 patients (M:F=25:19, age 57.1 year +/- 8.2) who had CABG before and 3 months after operation. We tried to find out possible causes for perfusion aggravation with multivariate logistic regression analysis regarding whether bypass graft was artery or vein and which coronary artery territory was operated. Among 616 myocardial segments which were operated, 89(14.4%) aggravated after operation In the univariate analysis, myocardial segments in the left circumflex arteries(I Cx) aggravated more often(p<0.01) than others and segments having operative angioplasty did less often(p<0.01). Multivariate logistic regression revealedthat LCx was risk factor for perfusion aggravation [odds ratio=2.54 (95% confidence interval : 1.53-4.22, p<0.01)] However, this was not the case when we analysed in terms of arterial territories. Among 106 coronary rterial territories which were operated. 27(25.5%) aggravated. The territories having aggravated had similar characterstics regarding whether they received arterial or venous grafts. Angioplasty and whether the operated territories were left anterior descending. Right coronary or left circumflex arteries. In conclusion, myocardial segments in the left circumflex artery tended to aggravate more often after bypass surgery than the others. In short-term comparison of perfusion after surgery. We could not find any tendency that arterial or venous fraft was associated with more frequency of the affravation of perfusion after operation.

Performance of Gated Myocardial Perfusion SPECT to Diagnose Coronary Artery Disease / 대한핵의학회잡지

We studied to investigate the predictive values of gated SPECT for the improvement of wall motion after bypass surgery. As we compared postoperative SPECT with preoperative ones, we defined viability as wall motion improvement. We performed rest T1-20l/stress Tc-99m-MIBI gated SPECT in 25 patients before and 3 months after bypass surgery. Myocardial wall motion was graded as normal, hypokinesia, a kinesia, and dyskinesia by pair-wise visual analysis of gated pre and postoperative SPECT's on the same monitor wall motion abnormalities before operation, 69 (75%) improved and 23 did not. Before operation, we could find segments with good systolic thickenining 64 segments among total 92. Thickening of the remaining 28 was poor. Wall motion improved postoperatively in 45 segments (70%) among 64 with good thickening, Twenty four(86%) among 28 segments with poor thickening had also improved. We grouped segments into mild(hypokinetic) and severe(akinetic/dyskinetic) ones. Among 33 segments with severe motion abnormalities, 14 had good thickening and 19 did not. Nine(60%) improved out of 14 segments having severe abnormality with good thickening. However, 16(84%) segments out of 19 having severe abnormality with poor thickening also improved. Neither degree of perfusion decrease nor severity of wall motion abnormalities could explain the high rate of false negatives. In conclusion, as we defined viability as wall motion improvement by comparing pre and postoperative SPECT, systolic thickening observed by gated Tc-99m-MIBI SPECT in myocardial segments with wall motion abnormalities predicted wall motion improvement after bypass surgery. However, poor thickening could not be referred as evidence of nonviable myocardium both in mild and severe contractile dysfunction, so that we might need stimulation study such as dobutamine echocardiography or dobutamine gated SPECT.

Transient Prolonged Stunning by Dipyridamole Stress Proved by Post-stress ( 1 hour ) and 24 hour Tc-99m-MIBI Gated SPECT / 대한핵의학회잡지

We performed 1st day Tc-99m-sestamibi gated SPECT with dipyridamole/rest T1-201 SPECT and 2nd day 24 hour delay T1-201 SPECT/rest Tc-99m-sestamibi gated SPECT in 27 patients with coronary artery disease(24) or having chest pain(3). Stress and rest Tc-99m- sestamibi gated SPECT was acquired at 60min post-injection. A 4-point scoring system(0 to 3 for normal to absent tracer uptake) for 17 segments was used. Wall motion was scored on another 4 point scale(0 to 3 for normal to dyskinesia) in the lst day post-stress gated and the 2nd day rest gated SPECT. Post-stress gated SPECT showed wall motion abnormality in 94 segments(20%). Fifty-five segments among these 94 showed the same wall motion between post-stress and rest gated SPECT:i.e. 1-1: 23 segments, 2-2: 29 segments, 3-3: 3 segments. Re-maining 39 segments (41.5%) showed different wall motion between post-stress and rest Tc-99m-sestamibi gated SFECT. Twenty one segments with wall motion abnormality had normal perfusion(rest:15 segments, 24 hour delay: 6 segments) at either rest or 24 hour delay. Fifteen among these 21 segments showed persistent post-stress and the 2nd day rest wall motion abnormality(persistent stunning). However, in 6 segments with prolonged (1 hour after stress) stunning, abnormal wall motion did improve in the 2nd day rest Tc-99m-sestamibi gated SPECT(transient prolonged stunning). These 6 segments had normal perfusion at rest(n=4) or at 24 hour delay(n=2). Post stress wall motions showed significantly higher scores in persistent stunning than in prolonged transient stunning(P value<0.05). It was concluded that we could find stunned myocardium with gated Tc-99m-sestamibi SPECT at either post-stress or rest and that some myocardial walls of post-stress 1 hour gated SPECT did not show truly rest wall motion. So, we should be cautious if we use post-stress Tc-99m-sestamibi wall motion to assess rest wall motion.