• Radiation Oncology Journal
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• v.25 no.1
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• pp.26-33
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• 2007

[ $\underline{Purpose}$ ]: The aim of this study is to evaluate and compare the incidence and aspects of myocardial perfusion defects in patients who were subjected to either two-dimensional or three-dimensional simulation techniques for early left-sided breast cancer. The myocardial perfusion defects were determined from using single photon emitted computerized tomography (SPECT) myocardial perfusion images. $\underline{Materials\;and\;Methods}$: Between January 2002 and August 2003, 32 patients were enrolled in this study. The patients were diagnosed as having early (AJCC stage T1-T2N0M0) left-sided breast cancer and were treated with tangential irradiation after breast-conserving surgery and systemic chemotherapy. The patients were divided into two groups according to the type of simulation received: two-dimensional simulation using an X-ray fluoroscope simulator or three-dimensional simulation with a CT simulator. All patients underwent technetium-99m-sestamibi gated perfusion SPECT at least 3 years after radiotherapy. The incidence and area of myocardial perfusion defects were evaluated and were compared in the two groups, and at the same time left ventricular ejection fraction and cardiac wall motion were also analyzed. The cardiac volume included in the radiation fields was calculated and evaluated to check for a correlation between the amount of irradiated cardiac volume and aspects of myocardial perfusion defects. $\underline{Results}$: A myocardial perfusion defect was detected in 11 of 32 patients (34.4%). There were 7 (46.7%) perfusion defect cases in 15 patients who underwent the two-dimensional simulation technique and 4 (23.5%) patients with perfusion defects in the three-dimensional simulation group (p=0.0312). In 10 of 11 patients who had myocardial perfusion changes, the perfusion defects were observed in the cardiac apex. The left ventricular ejection fraction was within the normal range and cardiac wall motion was normal in all patients. The irradiated cardiac volume of patients in the three-dimensional simulation group was less than that of patients who received the two-dimensional simulation technique, but there was no statistical significance as compared to the incidence of perfusion defects. $\underline{Conclusion}$: Radiotherapy with a CT simulator (three-dimensional simulation technique) for early left-sided breast cancer may reduce the size of the irradiated cardiac volume and the incidence of myocardial perfusion defects. Further investigation and a longer follow-up duration are needed to analyze the relationship between myocardial perfusion defects and clinical ischemic heart disease.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.36-42
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• 1997

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 SPECT in 44 patients (M:F=25:19, age 57.1 $year{\pm}8.2$) 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(LCx) aggravated more often(p<0.01) than others and segments having operative angioplasty did less often(p<0.01). Multivariate logistic regression revealed that 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 arterial territories which were operated, 27(25.5%) aggravated. The territories having aggravated had similar characteristics 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 graft was associated with more frequency of the aggravation of perfusion after operation.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.174-178
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• 2009

Many radiopharmaceuticals have been developed and wildy used in the imaging cardiac function. Myocardial perfusion imaging (MPI) is a well established noninvasive method of assessing coronary blood flow and has been widely used in patients diagnosed or suspected with coronary artery diseases. The innovation of radiopharmaceuticals used in the cardiac imaging is one of the most important contributors to the development of nuclear cardiology. Thallium-201 and various technetium-99m agents have been globally used for myocardial perfusion SPEG, and N-13 ammonia (13NH3), rubidium-82 (82Rb), 0-15 water (H2150) for myocardial perfusion PET. As well as the cardiac perfusion studies, new radiopharmaceuticals that visualize fat metabolism or receptors of the sympathetic nervous system have successfully been applied to clinical practice. Useful information can be obtained for diagnosing coronary artery disease, evaluating patients' condition, or assessing therapeutic effects. In this review, we describe the characteristics and clinical usefulness of radiopharmaceuticals used for cardiac SPEG and PET.

• Journal of Chest Surgery
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• v.25 no.1
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• pp.1-16
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• 1992

The quantitatively measured local myocardial perfusion rates with microspheres are used as an objective indicator of even distribution of cardioplegic solution, and the efficacy of the retrograde right atrial route of cardioplegia is evaluated in hearts with various levels of coronary arterial obstruction. After initial antegrade cardioplegia under the median sternotomy and aortic cannulation, 60 hearts from anesthetized New Zealand white rabbits are divided in random order as normal group [ligated left main coronary artery ; MA, MR] and diagonal group [ligated proximal diagonal artery ; LA, LR]. Half of each group [N=10] are perfused with antegrade cardioplegia[A] under the pressure of 100 cmH2O and the other half with retrograde right atrial route[R] under the pressure of 60 cmH2O[St. Thomas cardioplegic solution mixed with measured amount of microspheres]. The myocardium is subdivided into segments as A[atria], RV[right ventricle]. S[septum], LV[normally perfused left ventricular free wall], ROI[ischemic myocardium of left ventricular free wall]. LV and RQI are further divided into N[subendocardium] and P[subepicardium]. The resulting local myocardial perfusion rates and N /P of each group are compared with Wilcoxon rank sum test. The weight of the hearts is 5.94$\pm$0.66g, and there are no statistically significant dif-ferences[p>0.05, ANOVA] between six compared group. The mean flow rate[F: ml /g / min] of MR group is comparable with MA group[p>0.05], but in N and L group, there are significantly depressed F with right atrial route of cardioplegia, which means elevated perfusion resistance with this route. In spite of no significant differences in delivered doses of microsphere[DEL] between compared groups[p>0.05, ANOVA], there are significantly depressed REC and NF in hearts with right atrial cardioplegia which suggests increased requirement of cardioplegic solution with this route. The interventricular septum shows poor perfusion with right atrial route of cardioplegia without obstruction of supplying coronary arteries. But, with obstruction of coronary artery supplying septum as in M group, the flow rate is superior with right atrial route of infusion. The left ventricular free wall perfusion rates of every RQI with R route are superior to that of A route[p<0.05]. But, in LV segments, there are unfavorable effects of right atrial cardioplegia in L group, although the subendocardial perfusion is well maintained in N group. The LV free wall of left main group shows depressed perfusion rates with antegrade route as compared with RQI segments of diagonal group. But, by contraries, there are increased perfusion rates and superior N /P ratio with retrograde right atrial route. It implies more effective perfusion with right atrial route of cardioplegia in more proximal coronary arterial obstruction[i.e., M group as compared with L group]. As a conclusion, all region of ischemia have superior perfusion rates with right atrial car-dioplegia as compared with antegrade route, and especially excellent results can be obtained in hearts with more proximal obstruction of coronary arteries which would otherwise result in more severe ischemic damage. But, the depressed perfusion rates of the segments with normal coronary artery in hearts with coronary arterial obstruction may be a problem of concern with right atrial cardioplegia and needs solution.

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.86-94
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• 1996

Coronary angiography should be performed to verify the patency of bypass graft if coronary artery disease is said to be surgically corrected. Rest/stress myocardial SPECT could be used as a noninvasive alternative to prove patency of bypass graft and functional significance of graft patency by showing improvement of rest perfusion and perfusion reserve after operation. We evaluated the outcome of coronary artery bypass graft surgery by comparing rest/dipyridamole-stress myocardial SPECT before and after operation. Myocardial SPECT were performed $19{\pm}23$ days before and $108{\pm}19$ days after operation in 44 patients(M:F=25:19). Segmental perfusion were scored with 0(normal) to 3(defect) independently for each image set of rest and stress. Perfusion scores were compared between pre and postoperative images. Rest/stress images of pre and post-operative SPECT were compared in paired sets. Postoperative change of perfusion was determined as no change, improvement or aggravation for each artery territory. Postoperative outcome of patients were analyzed. Overall, 74%(158 segments) of 215 segments which had perfusion decrease before operation showed improvement. Among 60 artery territories, 37 territories(62%) improved. Among 42 patients with perfusion decrease in preoperative SPECT, 21 patients(47%) improved after operation. Severe persistent defects improved in 43%(6/14). We concluded that bypass surgery improved myocardial perfusion in dipyridamole stress induced or persistent decrease and that rest/stress myocardial SPECT could be used as a guide for which artery should be operated.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.231-238
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• 1995

Tc-99m-MIBI (Sestamibi) myocardial SPECT along with TI-201 tomographic Imaging has demonstrated wide application and high image quality sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow. The qualitative values of myocardial SPECT with Tc-99m-MIBI as well ds the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection (FBP) Is the common standard method for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected litter parameters such as cutoff frequencies and order (Butterworth case) The cutoff frequencies used in clinicAl practice partially remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for Identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable threshold of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Wyquist frequency would reveal severe degradation of radioactive distribution near inferior and/or inferoseptal myocardium when applying Butterworth or low pass filter.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.285-291
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• 2008

Purpose: Although automatic quantification software of myocardial perfusion SPECT provides highly objective and reproducible quantitative measurements, there is still some limitation in the direct use of quantitative measurements. In this study we derived parameters using normal variation of perfusion measurements, and tried to test the usefulness of these parameters. Materials and Methods: In order to calculate normal variation of perfusion measurements on myocardial perfusion SPECT, 55 patients (M:F = 28:27) of low-likelihood for coronary artery disease were enrolled and $^{201}TI$ rest/$^{99m}Tc$-MIBI stress SPECT studies were performed. Using 20-segment model, mean (m) and standard deviation (SD) of perfusion were calculated in each segment. As a myocardial viability assessment group, another 48 patients with known coronary artery disease, who underwent coronary artery bypass graft surgery (CABG) were enrolled. $^{201}TI$ rest/$^{99m}Tc$-MIBI stress / $^{201}TI$ 24-hr delayed SPECT was performed before CABG and SPECT was followed up 3 months after CABG. From the preoperative 24-hr delayed SPECT, $Q_{delay}$ (perfusion measurement), ${\Delta}_{delay}$ ($Q_{delay}$ - m) and $Z_{delay}$ (($Q_{delay}$ - m)/SD) were defined and diagnostic performances of them for myocardial viability were evaluated using area under curve (AUC) on receiver operating characteristic (ROC) curve analysis. Results: Segmental perfusion measurements showed considerable normal variations among segments. In men, the lowest segmental perfusion measurement was $51.8{\pm}6.5$ and the highest segmental perfusion was $87.0{\pm}5.9$, and they are $58.7{\pm}8.1$ and $87.3{\pm}6.0$, respectively in women. In the viability assessment $Q_{delay}$ showed AUC of 0.633, while those for ${\Delta}_{delay}$ and $Z_{delay}$ were 0.735 and 0.716, respectively. The AUCs of ${\Delta}_{delay}$ and $Z_{delay}$ were significantly higher than that of $Q_{delay}$ (p = 0.001 and 0.018, respectively). The diagnostic performance of ${\Delta}_{delay}$, which showed highest AUC, was 85% of sensitivity and 53% of specificity at the optimal cutoff of -24.7. Conclusion: On automatic quantification of myocardial perfusion SPECT, the normal variation of perfusion measurements were considerable among segments. In the viability assessment, the parameters considering normal variation showed better diagnostic performance than the direct perfusion measurement. This study suggests that consideration of normal variation is important in the analysis of measurements on quantitative myocardial perfusion SPECT.

• The Korean Journal of Nuclear Medicine
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• v.32 no.5
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• pp.433-435
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• 1998

Recent progress of technology permits us to assess ventricular function and wall motion as well as myocardial perfusion using electrocardiographic gated myocardial perfusion single photon emission computed tomography (GM-SPECT). It is interesting that echocardiography and magnetic resonance imaging are moving in the same direction with the use of contrast medium to assess myocardial perfusion. A valid fundamental basis for a new technology is essential for a successful competition. Lee et al. report in this issue the reproducibility of serial measurement of left ventricular function including systolic wall thickening using a novel statistical method. It has important implications such as nitroglycerin or dobutamine application during GM-SPECT. The field of nuclear cardiology must continue to strive toward more sophisticated but straightforward evaluation of cardiac diseases.

• Journal of Chest Surgery
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• v.30 no.11
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• pp.1083-1091
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• 1997

This study was purposed to assess the result of coronary artery bypass graft surgery by analyzing and comparing the pre and postoperative myocardial perfusion state quantitatively by using myocardial SPECT. Twenty patients who received coronary artery bypass graft surgery since 1993 underwent both preoperative and postoperative myocardial SPECT and the result were analyzed. The mean age was 56.4$\pm$9.0 years, and the patients were composed of thirteen males and seven females. For quantitative analysis, we used polar maps of SPECT generated by Cedars-Sin i Medical Center program and we calculated perfusion scores, ischemic myocardial area ratios and reperfusion scores from polar maps. Preoperative mean stressfrest perfusion score was 7.3$\pm$ 1.117.7$\pm$ 1.0 and postoperative score was 8.1 $\pm$ 1 118.3$\pm$ 1.1. Preoperative mean stress ischemic myocardial area ratio was 0.32$\pm$0.2 and postoperative ratio was 0.15 $\pm$0.1. Postoperative mean perfusion score was significantly increased but, on the other hand, mean ischemic myocardial area ratio was significantly decreased as compared with preoperative values(p<0.01). Preoperative mean perfusion score of patients with postoperative roper(usion score more than 1.5 was significantly higher(p<0.01) than that of patients with postoperative reperfusion score less than 1.5. Preoperative perfusion scores of coronary artery territories that had fixed perfusion defect at myocardial SPECT were significantly low(4.3 $\pm$0.514.6$\pm$0.6, stresslrest), nevertheless it proved quantitatively that there was improvement in myocardial perfusion after surgery by showing improved perfusion scores postoperatively. In conclusion, myocardial SPECT is useful method for quantitative analysis of the myocardial perfusion state after coronary artery bypass grafting surgery.

• The Korean Journal of Nuclear Medicine
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• v.36 no.6
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• pp.381-391
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• 2002

Purpose: The presence of perfusion defect may influence the left ventricular mass (LVM) measurement by quantitative gated myocardial perfusion SPECT (QGS), and ischemic myocardium, usually showing perfusion defect may produce post-stress LV dysfunction. This study was aimed to evaluate the effects of extent and reversibility of perfusion defect on the automatic measurement of LVM by QGS and to investigate the effect of reversibility of perfusion defect on post-stress LV dysfunction. Subjects and Methods: Forty-six patients (male/female=34:12, mean age=64years) with perfusion defect on myocardial perfusion SPECT underwent rest and post-stress QGS. Forty patients (87%) showed reversible defect. End-diastolic volume (EDV), end-systolic volume (ESV), LV ejection fraction (EF), and LV myocardial volume were obtained from QGS by AutoQUANT program, and LVM was calculated by multiplying the LV myocardial volume by the specific gravity of myocardium. Results: LVMs measured at rest and post-stress QGS showed good correlation, and higher correlation was founded in the subjects with fixed perfusion defect and with small defect (smaller than 20%). There were no significant differences in EDVs, ESVs and EFs between obtained by rest and post-stress QGS un patients with fixed myocardial defect. Whereas, EF obtained by post-stress QGS was lower than that by rest QGS in patients with reversible defect and 10 (25%) of them showed decreases in EF more than 5% in post-stress QGS, as compared to that of rest QGS. Excellent correlations of EDVs, ESVs, EFs between rest and post-stress QGS were noted. Patients with fixed defect had higher correlation between EDVs, ESVs, EFs than patients with reversible defect. Conclusion: These results suggest that perfusion defect can affect LVM measurement by QGS and patients with reversible defect shows post-stress LV dysfunction more frequently than patients with fixed perfusion defect.