[MR imaging in the assessment of the extent of myocardial infarction].
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Biomedical subjects
Won Yong Kim
Publications and source records attributed to Won Yong Kim.
Electromechanical mapping versus positron emission tomography and single photon emission computed tomography for the detection of myocardial viability in patients with ischemic cardiomyopathy.
OBJECTIVES: We compared catheter-based electromechanical mapping (NOGA system, Biosense-Webster, Haifa, Israel) with positron emission tomography (PET) and single photon emission computed tomography (SPECT) for prediction of reversibly dysfunctional myocardium (RDM) and irreversibly dysfunctional myocardium (IDM) in patients with severe left ventricular dysfunction. Furthermore, we established the optimal discriminatory value of NOGA measurements for distinction between RDM and IDM. BACKGROUND: The NOGA system can detect viable myocardium but has not been used for prediction of post-revascularization contractile function in patients with ischemic cardiomyopathy. METHODS: Twenty patients (19 males, age [mean +/- SD] 60 +/- 16 years, ejection fraction [EF] 29 +/- 6%) underwent viability testing with NOGA and PET or SPECT before revascularization. Left ventricular function was studied at baseline and six months after revascularization. RESULTS: The EF increased to 34 +/- 13% at six months (p < 0.05 vs. baseline). The 58 RDM and 57 IDM regions differed with regard to unipolar voltage amplitude (UVA) (9.2 +/- 3.9 mV vs. 7.6 +/- 4.0 mV, p < 0.05), normalized UVA (106 +/- 54% vs. 75 +/- 39%, p < 0.05), and tracer uptake (76 +/- 17% vs. 60 +/- 20%, p < 0.05). The NOGA local shortening did not distinguish between RDM and IDM (6.4 +/- 5.8% vs. 5.4 +/- 6.6%). By receiver operating characteristic curve analysis, myocardial tracer uptake had better diagnostic performance than UVA (area under curve [AUC] +/- SE: 0.82 +/- 0.04 vs. 0.63 +/- 0.05, p < 0.05) and normalized UVA (AUC +/- SE: 0.70 +/- 0.05, p < 0.05). Optimal threshold was defined as the value yielding sensitivity = specificity for prediction of RDM. Sensitivity and specificity were 59% at a UVA of 8.4 mV, 65% at a normalized UVA of 83%, and 78% at a tracer uptake of 69%. CONCLUSIONS: The NOGA system may discriminate RDM from IDM with optimal discriminatory values for UVA and normalized UVA of 8.4 mV and 83%, respectively. However, the diagnostic performance does not reach the level obtained by PET and SPECT in patients with severe heart failure.
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The impact of spatial resolution and respiratory motion on MR imaging of atherosclerotic plaque.
PURPOSE: To examine the impact of spatial resolution and respiratory motion on the ability to accurately measure atherosclerotic plaque burden and to visually identify atherosclerotic plaque composition. MATERIALS AND METHODS: Numerical simulations of the Bloch equations and vessel wall phantom studies were performed for different spatial resolutions by incrementally increasing the field of view. In addition, respiratory motion was simulated based on a measured physiologic breathing pattern. RESULTS: While a spatial resolution of > or = 6 pixels across the wall does not result in significant errors, a resolution of < or = 4 pixels across the wall leads to an overestimation of > 20%. Using a double-inversion T2-weighted turbo spin echo sequence, a resolution of 1 pixel across equally thick tissue layers (fibrous cap, lipid, smooth muscle) and a respiratory motion correction precision (gating window) of three times the thickness of the tissue layer allow for characterization of the different coronary wall components. CONCLUSIONS: We found that measurements in low-resolution black blood images tend to overestimate vessel wall area and underestimate lumen area.
Arteriosclerosis↗
Sequential versus simultaneous biventricular resynchronization for severe heart failure: evaluation by tissue Doppler imaging.
BACKGROUND: Cardiac resynchronization therapy (CRT) by means of simultaneous biventricular pacing improves left ventricular systolic performance and synchrony in patients with heart failure and bundle-branch block. We used tissue tracking and 3D echocardiography to evaluate the impact of sequential CRT with individualized interventricular delay programming. METHODS AND RESULTS: Twenty consecutive patients with severe heart failure and left bundle-branch block were included. Tissue tracking and 3D echocardiography were carried out before and on the day after pacemaker implantation. Eleven different interventricular delays were examined in each patient. Patients were reexamined after 3 months. Simultaneous CRT immediately reduced the extent of myocardium displaying delayed longitudinal contraction (DLC) from 48.6+/-16% to 23.2+/-13% (P<0.01) and increased left ventricular ejection fraction percentage (LVEF%) from 22.4+/-6% to 29.7+/-5% (P<0.01). However, optimum sequential CRT caused a further reduction in the extent of DLC from 23.2+/-13% to 11.1+/-7.2% (P<0.01), with a simultaneous increase in LVEF% (from 29.7+/-5% to 33.9+/-6%, P<0.01). Three months of optimum sequential CRT further improved LVEF% (from 33.6+/-6% to 38.6+/-7.2%, P<0.01). Tissue tracking detected the segments with DLC, and their location determined optimum interventricular delay programming. Compared with simultaneous CRT, sequential CRT increased diastolic filling time by 7+/-2.5%. CONCLUSIONS: Compared with simultaneous CRT, sequential CRT significantly improves left ventricular systolic and diastolic performance. Tissue tracking can be used to select optimum interventricular delay during CRT.
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Production of hybrid double- or triple-layered virus-like particles of group A and C rotaviruses using a baculovirus expression system.
Dual infections by group A and group C rotaviruses have been reported, but no reassortants between group A and group C rotaviruses have been described. The VP6 major inner capsid protein of group A and C rotaviruses shares common antigens detected by monoclonal antibodies and also shares 40-43% amino acid identity. Coinfection of Spodoptera frugiperda (Sf9) insect cells with different combinations of the recombinant baculoviruses encoding either group A [RF VP2 (A-VP2), IND VP6 (A-VP6), and VP7 (A-VP7[IND]), 2292B VP7 (A-VP7[2292B])] or C [Shintoku VP6 (C-VP6) and VP7 (C-VP7)] bovine rotavirus proteins produced hybrid group A/C triple-layered VP2/6/7 virus-like particles (TLPs) composed of A-VP2/C-VP6/C-VP7, A-VP2/C-VP6/A-VP7(IND), A-VP2/C-VP6/A-VP7(2292B), and A-VP2/A-VP6/C-VP7. To our knowledge, this is the first report that the inner capsid VP6 of group A or group C rotavirus can support attachment of the heterologous, antigenically distinct group A (G6, IND or G10, 2292B) or group C rotavirus outer capsid VP7 to produce hybrid TLPs in vitro.
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