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ObjectiveTo investigate reproducibility of cardiac MRI for assessment of cardiac morphology and ventricular function in selected normal Chinese Han population.MethodsTwo hundred and sixty-nine normal volunteers underwent cardiac MRI using a 1.5 T MR system.HASTE and steady state free precession imaging were performed with long and short axis images and cine mode through the ventricle with wireless vector cardiac gating.The images were reviewed by two independent observers.The dimensions of cardiac chambers and ventricular function including ejection fraction (EF),end diastolic volume( EDV),end systolic volume (ESV) and myocardial mass were evaluated.The data between male and female were compared by using two-tailed unpaired t test.Results Total imaging time was (15 ± 3 ) min.The anteroposterior diameter of the left atrium was( 2.87 ± 0.77 ) cm,the right atrial diameter perpendicular to the atrial septum was ( 3.61 ± 0.57 ) cm,the end diastolic diameter of the left ventricle was (4.97 ±0.52) cm,the end diastolic diameter of the right ventricle was (2.65 ± 0.48) cm.On the left ventricle,EF was(60.62 ±7.08)％,EDV was (115.37 ±26.71) ml,ESV was (46.02+15.72) ml and LV mass was ( 82.97± 24.03 ) g.On the right ventricle,EF was (47.73 ± 6.50 ) ％,EDV was ( 128.27 ± 32.16 )ml,ESV was (67.7 ± 21.07) ml and RV mass was (48.24 ± 13.42) g.There were no statistically significant differences in LVESV( P =0.144 ),LVEDV index ( P =0.714 ),LVESV index ( P =0.113 ),LVCI ( P =0.199),RVEF ( P =0.296 ) and RV mass ( P =0.093 ),and statistically significant differences in other cardiac parameters between male and female.Conclusion Cardiac MRI can provide useful information about cardiac function and morphology with a high level of reproducibility in normal Chinese Han population.
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Objective To analyze the characteristics of hypertrophic cardiomyopathy (HCM) on delayed contrast-enhanced cardiac magnetic resonance imaging (CMRI). Methods All patients underwent delayed contrast-enhanced CMRI. The left ventricle was divided into 9 segments to assess the location,extent and function of the hypertrophic segments. The t test was applied for the statistics. Results Of 154 patients, delayed enhancement of hypertrophic segment was found in 95 cases and non-delayed enhancement in 59 cases. The thickness and number of hypertrophic segment in patients with delayed enhancement were larger than those with non-delayed enhancement [ (24. 8 ± 5. 5 ) mm vs (20. 4 ±3.8) mm, t = 3.82, P < 0.05; (3.3 ± 1.9) vs (2.4 ± 1.7), t = 2. 26, P < 0.05 ], and the age was younger [ (46. 0 ± 15.2) years vs (55.0 ± 11.9) years, t = - 3. 67, P <0. 05 ]. The diffuse enhancement was found in 62 patients, and confluent enhancement in 33 patients. Confluent enhancement was found in all 14 patients after the alcohol ablation procedure. Conclusion The age, thickness and number of hypertrophic segments in patients with delayed enhancement are different from those with non-delayed enhancement.
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ObjectiveTo investigate the effects of autologous bone marrow-derived mesenchymal stem cells (MSCs)transplantation on acute myocardial infarction in swine models using MRI. MethodsFourteen Chinese mini-pigs(27±3 kg)were divided into control group(n=7)and transplantation group(n=7).Acute myocardial infarction(AMI)model was made by occlusion of the left anterior descending coronary artery for 90 minutes,and then 10 ml autologous MSCs(3 × 106 cell/ml)were injected into LAD by over-wire-balloon catheter after one week. MRl was performed to assess the cardiac function and myocardial perfusion 1 week after AMI and 6 weeks after transplantation.The implanted cells in vitro were analyzed by immunofluorescence.ResuitsThe left ventricular ejection fraction(LVEF)in transplantation group was increased from(42.7 ±7.5)%to(50.1±10.1)%,which was significantly different from that in control group(P＜0.01).In addition,the dyskinetic segments in infarcted region and the infareted area were decreased by 4 and 3.2 cm2 respectively(P＜0.01),and the left ventricular weight index was increased by 4.1 g/m2 in transplantation group(P＜0.05)compared with control group.The DAPI-labeled cells in infarcted and peri-infarcted region indicated the survived MSCs.Immunofluoreseence also confirmed that those cells expressed cardiomyocyte-specific troponin T,connexin 43 and vessel-specific smooth muscle actin.Capillary density in both infarcted and peri-infarcted region were higher in transplantation group than the control group(P＜0.01).Conclusion MRI is a reliable imaging method for assessing the effects of stem cell transplantation in acute myocardial infartion of swine models.
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<p><b>OBJECTIVE</b>To evaluate the diagnostic value of dobutamine stress magnetic resonance imaging (MRI) for myocardial viability.</p><p><b>METHODS</b>Ten male miniswines underwent left ventriculography and coronary angiography, followed by stenosis of the left circumflex coronary artery (LCX) using ameroid constrictor. More than one month later, left ventriculography and coronary angiography were performed again, followed by cine-MRI at rest and during stress with incremental dose of dobutamine 5 - 20 micro g.kg(-1).min(-1). Traditional and/or breath-hold cine-MRI were used to evaluate regional left ventricular wall motion, corresponding to basal, midventricular and apical short-axis tomograms. Regional wall motion score index (WMSI) was calculated. The miniswines were finally sacrificed for pathological examination. Triphenyl tetrazolium chloride (TTC) delineated myocardial infarction. Microscopy was used to identify myocardial cellular changes.</p><p><b>RESULTS</b>One pig died, one pig suffered from aneurysm and another showed no negative findings. The other seven pigs were found with hypokinetic (n = 4) or akinetic (n = 3) myocardial regions related to stenosed LCX. Their mean WMSI at rest for the lateral and posteroinferior walls (ischemic regions) of the left ventricle was 2.27 +/- 0.32, as compared with 1.00 +/- 0.00 (P < 0.01) for the corresponding nonischemic anteroseptal regions. Further, the mean WMSI for the ischemic regions was 2.27 +/- 0.32 at rest compared with 1.40 +/- 0.39 (P < 0.01) at the dose of dobutamine 5 micro g.kg(-1).min(-1). However, the mean WMSI at the doses of dobutamine 10 and 20 micro g.kg(-1). min(-1) were 1.70 +/- 0.76 and 1.75 +/- 0.83, respectively, with no significant difference as compared with the mean WSCI at rest (P > 0.05). The pathologic examination showed viable myocardium at the ischemic regions.</p><p><b>CONCLUSION</b>Low-dose dobutamine (5 micro g.kg(-1).min(-1)) recovers hypokinetic or akinetic myocardial regions, and dobutamine stress MRI can be used to detect myocardial viability.</p>
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Animals , Male , Dobutamine , Magnetic Resonance Imaging, Cine , Methods , Swine , Swine, Miniature , Ventricular Function, LeftABSTRACT
Objective To establish the chronic low flow myocardial hibernation animal model in pigs, and to assess the diagnostic value for myocardial hibernation by using various imaging methods. Methods A total of 13 miniswine (30-40 kg) were used. All animals underwent general anesthesia and orotracheal intubation while the animals were mechanically ventilated. Under sterile conditions, left ventriculography and coronary angiography were performed by introduction of catheter into the right femoral artery. Further, a left anterolateral thoracotomy was performed in the third intercostal space. The proximal LCX was dissected free to allow placement of an ameroid constrictor. More than 1 month later, left ventriculography and coronary angiography were performed again, followed by cine MRI at rest and during stress with low dose of dobutamine (5 ?g?kg -1 ?min -1 ), respectively. Traditional and/or breath hold cine MRI were used to evaluate regional left ventricular wall motion, corresponding to basal, midventricular and apical short axis tomograms. Regional wall motion score index (WMSI) was calculated. At the same time 99m Tc MIBI myocardial SPECT was performed at rest and during nitroglycerin administration, respectively. All animals were finally sacrificed for pathological examination. Triphenyl tetrazolium chloride (TTC) staining was used to assess the myocardial infarction. Electron microscopy was used to identify myocardial cellular changes characteristic of hibernating myocardium. Results Three pigs died during surgery or within two weeks after surgery. One pig died of anesthesia during SPECT examination, 1 pig suffered from aneurysm, and another one pig showed negative findings. The other 7 pigs were found with hypokinetic ( n =4) or akinetic ( n =3) myocardial regions related to stenosed LCX (70%-99%). Resting cine MRI demonstrated decreased regional motion of the lateral and posteroinferior walls (ischemic regions) of the left ventricle ( n =7), compared with the nonischemic anteroseptal regions; but the low dose dobutamine (5 ?g?kg -1 ?min -1 ) could recover those hypokinetic or akinetic myocardial regions, characteristic of hibernating myocardium. Resting 99m Tc MIBI myocardial SPECT ( n =6) showed a fixed perfusion defect on the corresponding ischemic areas, which became reversible on the nitrate augmented myocardial perfusion imaging. It also indicated myocardial viability presented at the ischemic areas. TTC staining revealed patchy infarction of the area at risk localized to the endocardial surface ( n =3), and no myocardial infarction ( n =4). Electron microscopy of sections from the hibernating regions revealed loss of contractile materials, increased numbers of small mitochondria, and glycogen accumulation within viable cardiomyocytes, which had been described as hallmarks of hibernating myocardium. Conclusion Chronic low flow myocardial hibernation can be reproduced in an animal model during progressive coronary stenosis caused by ameroid constrictor.