• Journal of Chest Surgery
• /
• 제37권9호
• /
• pp.755-761
• /
• 2004

We evaluated the efficacy of Dor procedure in patients with ischemic left ventricular dysfunction. Material and Method: Between April 1998 and December 2002, 45 patients underwent the Dor procedure con-comitant with coronary artery bypass grafting (CABG). Left ventricular ejection fraction (LVEF) and left ventricular end-diastolic/end-systolic volumes (LVEDV/LVESV) were measured by echocardiography, myocardial SPECT, and cardiac catheterization and angiography performed at the sequence of preoperative, early postoperative, and one year postoperative stage. Result: Cardiopulmonary bypass and aortic clamp times were mean 141$\pm$64, 69$\pm$24 minutes, respectively. Intraaortic balloon pump (IABP) therapy was required in 19 patients (42%; 7 preoperatively, 9 intraoperatively, 3 postoperatively). Operative mortality rate was 2.2% (1/45). Postoperative morbidities were low cardiac output syndrome (12), atrial fibrillation (5), acute renal failure (4), and postoperative bleeding (4). Functional class (NYHA) was improved from classes 2.8 to 1.1 (p < 0,01). When we compared between the preoperative and early postoperative values, LVEF was improved from 32$\pm$9% to 52$\pm$11% (p<0.01). The asynergy portion decreased from 57$\pm$12% to 22$\pm$9%, and LVEDV/LVESV indexes improved from 125$\pm$39 mL/$m^2$, 85$\pm$30 mL/$m^2$ to 66$\pm$23 mL/$m^2$, 32$\pm$16 mL/$m^2$ (p<0.01). Although these changes in volumes were relatively preserved at postoperative one year, the left ventricular volumes showed a tendency to increase. Conclusion: After the Dor procedure for ischemic left ventricular dysfunction, LVEF improvement and left ventricular volume reduction were maintained till postoperative one year. The tendency for left ventricular volume to increase at postoperative one year suggested the requirement of strict medical management.

• The Korean Journal of Nuclear Medicine
• /
• 제38권6호
• /
• pp.486-491
• /
• 2004

Purpose: factor analysis and independent component analysis (ICA) has been used for handling dynamic image sequences. Theoretical advantages of a newly suggested ICA method, ensemble ICA, leaded us to consider applying this method to the analysis of dynamic myocardial $H_2^{15}O$ PET data. In this study, we quantified patients' blood flow using the ensemble ICA method. Materials and Methods: Twenty subjects underwent $H_2^{15}O$ PET scans using ECAT EXACT 47 scanner and myocardial perfusion SPECT using Vertex scanner. After transmission scanning, dynamic emission scans were initiated simultaneously with the injection of $555{\sim}740$ MBq $H_2^{15}O$. Hidden independent components can be extracted from the observed mixed data (PET image) by means of ICA algorithms. Ensemble learning is a variational Bayesian method that provides an analytical approximation to the parameter posterior using a tractable distribution. Variational approximation forms a lower bound on the ensemble likelihood and the maximization of the lower bound is achieved through minimizing the Kullback-Leibler divergence between the true posterior and the variational posterior. In this study, posterior pdf was approximated by a rectified Gaussian distribution to incorporate non-negativity constraint, which is suitable to dynamic images in nuclear medicine. Blood flow was measured in 9 regions - apex, four areas in mid wall, and four areas in base wall. Myocardial perfusion SPECT score and angiography results were compared with the regional blood flow. Results: Major cardiac components were separated successfully by the ensemble ICA method and blood flow could be estimated in 15 among 20 patients. Mean myocardial blood flow was $1.2{\pm}0.40$ ml/min/g in rest, $1.85{\pm}1.12$ ml/min/g in stress state. Blood flow values obtained by an operator in two different occasion were highly correlated (r=0.99). In myocardium component image, the image contrast between left ventricle and myocardium was 1:2.7 in average. Perfusion reserve was significantly different between the regions with and without stenosis detected by the coronary angiography (P<0.01). In 66 segment with stenosis confirmed by angiography, the segments with reversible perfusion decrease in perfusion SPECT showed lower perfusion reserve values in $H_2^{15}O$ PET. Conclusions: Myocardial blood flow could be estimated using an ICA method with ensemble learning. We suggest that the ensemble ICA incorporating non-negative constraint is a feasible method to handle dynamic image sequence obtained by the nuclear medicine techniques.

• The Korean Journal of Nuclear Medicine
• /
• 제36권1호
• /
• pp.1-7
• /
• 2002

Positron Emission Tomography (PET) is a nuclear medicine imaging modality that consists of systemic administration to a subject of a radiopharmaceutical labeled with a positron-emitting radionuclide. Following administration, its distribution in the organ or structure under study can be assessed as a function of time and space by (1) defecting the annihilation radiation resulting from the interaction of the positrons with matter, and (2) reconstructing the distribution of the radioactivity from a series of that used in computed tomography (CT). The nuclides most generally exhibit chemical properties that render them particularly desirable in physiological studies. The radionuclides most widely used in PET are F-18, C-11, O-15 and N-13. Regarding to the number of the current PET Centers worldwide (based on ICP data), more than 300 PET Centers were in operation in 2000. The use of PET technology grew rapidly compared to that in 1992 and 1996, particularly in the USA, which demonstrates a three-fold rise in PET installations. In 2001, 194 PET Centers were operating in the USA. In 1994, two clinical and research-oriented PET Centers at Seoul National University Hospital and Samsung Medical Center, was established as the first dedicated PET and Cyclotron machines in Korea, followed by two more PET facilities at the Korea Cancer Center Hospital, Ajou Medical Center, Yonsei University Medical Center, National Cancer Center and established their PET Center. Catholic Medical School and Pusan National University Hospital have finalized a plan to install PET machine in 2002, which results in total of nine PET Centers in Korea. Considering annual trends of PET application in four major PET centers in Korea in Asan Medical Center recent six years (from 1995 to 2000), a total of 11,564 patients have been studied every year and the number of PET studies has shown steep growth year upon year. We had 1,020 PET patients in 1995. This number increased to 1,196, 1,756, 2,379, 3,015 and 4,414 in 1996,1997,1998,1999 and 2000, respectively. The application in cardiac disorders is minimal, and among various neuropsychiatric diseases, patients with epilepsy or dementia can benefit from PET studios. Recently, we investigated brain mapping and neuroreceptor works. PET is not a key application for evaluation of the cardiac patients in Korea because of the relatively low incidence of cardiac disease and less costly procedures such as SPECT can now be performed. The changes in the application of PET studios indicate that, initially, brain PET occupied almost 60% in 1995, followed by a gradual decrease in brain application. However, overall PET use in the diagnosis and management of patients with cancer was up to 63% in 2000. The current medicare coverage policy in the USA is very important because reimbursement policy is critical for the promotion of PET. In May 1995, the Health Care Financing Administration (HCFA) began covering the PET perfusion study using Rubidium-82, evaluation of a solitary pulmonary nodule and pathologically proven non-small cell lung cancer. As of July 1999, Medicare's coverage policy expanded to include additional indications: evaluation of recurrent colorectal cancer with a rising CEA level, staging of lymphoma and detection of recurrent or metastatic melanoma. In December of 2001, National Coverage decided to expand Medicare reimbursement for broad use in 6 cancers: lung, colorecctal, lymphoma, melanoma, head and neck, and esophageal cancers; for determining revascularization in heart diseases; and for identifying epilepsy patients. In addition, PET coverage is expected to further expand to diseases affecting women, such as breast, ovarian, uterine and vaginal cancers as well as diseases like prostate cancer and Alzheimer's disease.

• The Korean Journal of Nuclear Medicine
• /
• 제31권1호
• /
• pp.73-82
• /
• 1997

Regional myocardial blood flow (rMBF) can be noninvasively quantified using N-13 ammonia and dynamic positron emission tomography (PET). The quantitative accuracy of the rMBF values, however, is affected by the distortion of myocardial PET images caused by finite PET image resolution and cardiac motion. Although different methods have been developed to correct the distortion typically classified as partial volume effect and spillover, the methods are too complex to employ in a routine clinical environment. We have developed a refined method incorporating a geometric model of the volume representation of a region-of-interest (ROI) into the two-compartment N-13 ammonia model. In the refined model, partial volume effect and spillover are conveniently corrected by an additional parameter in the mathematical model. To examine the accuracy of this approach, studies were performed in 9 coronary artery disease patients. Dynamic transaxial images (16 frames) were acquired with a GE $Advance^{TM}$ PET scanner simultaneous with intravenous injection of 20 mCi N-13 ammonia. rMBF was examined at rest and during pharmacologically (dipyridamole) induced coronary hyperemia. Three sectorial myocardium (septum, anterior wall and lateral wall) and blood pool time-activity curves were generated using dynamic images from manually drawn ROIs. The accuracy of rMBF values estimated by the refined method was examined by comparing to the values estimated using the conventional two-compartment model without partial volume effect correction rMBF values obtained by the refined method linearly correlated with rMBF values obtained by the conventional method (108 myocardial segments, correlation coefficient (r)=0.88). Additionally, underestimated rMBF values by the conventional method due to partial volume effect were corrected by theoretically predicted amount in the refined method (slope(m)=1.57). Spillover fraction estimated by the two methods agreed well (r=1.00, m=0.98). In conclusion, accurate rMBF values can be efficiently quantified by the refined method incorporating myocardium geometric information into the two-compartment model using N-13 ammonia and PET.

• The Korean Journal of Nuclear Medicine Technology
• /
• 제22권2호
• /
• pp.88-91
• /
• 2018

Purpose The purpose of this study is to investigate the simultaneous dual isotope (SDI) myocardial perfusion scan that can be performed in a short time using a semiconductor gamma camera. Materials and Methods Of the 86 patients who underwent Rest/Stress $^{99m}TC$-sestaMIBI 1-day myocardial perfusion scan and Rest $^{99m}TC$-sestaMIBI/Stress $^{201}Tl$ simultaneous dual isotope myocardial perfusion scan using a heart-only gamma camera, the test results were the same, 36 patients who did not show any change in the clinical outcome. Quantitative values were statistically analyzed using a QPS program to confirm the correlation between the images of the two examinations. Results Rest/Stress $^{99m}TC$-sestaMIBI simultaneous dual myocardial perfusion scans and $^{99m}TC$-sestaMIBI/Stress $^{201}Tl$ double-isotope myocardial perfusion scans were analyzed for Summed score. The $R^2$ value of the Rest summed score (RSS) was 0.91 and the $R^2$ value of the stress summed score (SSS) was 0.71. Conclusion The $^{99m}TC$-sestaMIBI/Stress $^{201}Tl$ simultaneous dual isotope scan confirmed its correlation with the previous day's test. The $^{99m}TC$-sestaMIBI/Stress $^{201}Tl$ simultaneous dual isotope scan can be completed in approximately 30minutes. It maybe clinically useful for patients who need short examination time such as emergency patients or elderly patients.