ABSTRACT
<p><b>OBJECTIVE</b>To investigate the feasibility of using intravascular loopless monopole antenna (ILMA) to image atherosclerosis plaque in a porcine model with 3.0T magnetic resonance imaging (MRI).</p><p><b>METHODS</b>Atherosclerosis model was established by feeding high fat diet combined with balloon catheter injury to the endothelium in 6 pigs. After 3 months, animals underwent MRI and ILMA examination. The ILMA was invasively inserted to the distal part of abdominal vein and bilateral common iliac veins. MR sequences including T1 weighted imaging (T1WI), T2WI were obtained. MR image data were transferred to post-processing station. Luminal border and external elastic membrane of the vessel were reconstructed based on the MR images. After co-register these images, vessel area, lumen area, vessel wall area and plaque burden in the same lesions imaged by different modality were calculated and compared. Finally, all animals were scarified and hematoxylin eosin (HE) staining was performed in the targeted vessels. Diagnostic accuracy of MR in delineating vessel wall and detecting plaque were analyzed and calculated by comparing with pathological results.</p><p><b>RESULTS</b>The atherosclerotic model was successfully established in all 6 pigs. Good agreement of delineating vessel area, lumen area vessel, wall area and plaque burden were found between MRI and pathology with r value of 0.98, 0.95, and 0.96, respectively (P < 0.001). Compared with pathological findings, the plaque component in corresponding area imaged by MR was as follows: sensitivity and specificity of detecting lipid plaque were 77% and 69%, kappa value was 0.75 ± 0.19 (P < 0.01); sensitivity and specificity on detecting fibrotic plaque were 78% and 73%, Κ value was 0.78 ± 0.18 (P < 0.01). The sensitivity and specificity of detecting calcified plaque were 100%. ILMA results showed that the average lumen area was 49.72 mm(2), average vessel area was 124.08 mm(2), and the average vessel wall area was 74.37 mm(2), ILMA slightly overestimated these indexes as compared with pathological results.</p><p><b>CONCLUSION</b>The results showed that ILMA could be used to image deepened artery and atherosclerotic plaque. Detected plaque size, vessel area, lumen area vessel, wall area, and plaque burden were comparable to pathological findings. It may thus provide an alternative method for detecting atherosclerotic plaque in future research work.</p>
Subject(s)
Animals , Disease Models, Animal , Magnetic Resonance Angiography , Methods , Plaque, Atherosclerotic , Diagnosis , Swine , Swine, MiniatureABSTRACT
Objective To evaluate the image quality (IQ) and radiation dose of 128-slice dual-source computed tomography (DSCT) coronary angiography using prospectively electrocardiogram (ECG)-triggered sequential scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrillation referred for a second-generation 128-slice DSCT coronary angiography were included in the prospective study. Of them, 17 patients (sequential group) were randomly selected to use a prospectively ECG-triggered sequential scan, while the other 15 patients (spiral group) used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel-lent (grade 1) to non-assessable (grade 4), based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each patient were compared between the two groups. Results The mean heart rate (HR) of the sequential group was 96±27 beats per minute (bpm) with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean HR (t=1.91, P=0.243) and HR variation range (t=0.950, P=0.350) had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent (grade 1) in 190/244 (78%) vs. 177/217 (82%) by reader1 and 197/245 (80%) vs. 174/214 (81%) by reader2, as non-assessable (grade 4) in 4/244 (2%) vs. 2/217 (1%) by reader1 and 6/245 (2%) vs. 4/214 (2%) by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good (1.27±0.19 vs. 1.25±0.22, Z=-0.834, P=0.404). The effective radiation dose of the sequential group reduced significantly compared with the spiral group (4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000). Conclusion Compared with retrospectively ECG-gated spiral scan, prospectively ECG-triggered sequential DSCT coronary angiography provides similarly diagnostically valuable images in patients with atrial fibrillation and significantly reduces radiation dose.
Subject(s)
Humans , Atrial Fibrillation , Coronary Angiography , Electrocardiography , Prospective Studies , Radiation Dosage , Tomography, Spiral ComputedABSTRACT
<p><b>BACKGROUND</b>Noninvasive detection of vulnerable plaque has a significant implication for prevention and treatment of atherosclerotic diseases. The aim of this study is to investigate the difference between vulnerable plaques and stable plaques in magnetic resonance (MR) images.</p><p><b>METHODS</b>Atherosclerosis was induced in twenty male New Zealand white rabbits by high cholesterol diet and balloon injury of the abdominal aorta. After baseline (pre-triggering) MR imaging (MRI) scan, the rabbits underwent pharmaceutical triggering with Russell's viper venom and histamine to induce atherothrombosis, followed by another MRI scan 48 hours later (post-triggering). Rabbits were euthanized to obtain pathological and histological data. The results of MRI were compared with those of pathology and histology.</p><p><b>RESULTS</b>MRI showed that abdominal aorta of the rabbits had pathological change of atherosclerosis in different degrees. Seventy-five plaques were analysed, among which 14 had vulnerable thrombi and 61 stable. Thrombosis was identified in 7 of 11 rabbits by post-triggering MRI, the sensitivity and K value of MR in detection of vulnerable plaque was 71% and 0.803 (P < 0.05). MRI data significantly correlated with the histopathological data in fibrous cap thickness (r = 0.749) plaque area (r = 0.853), lipid core area (r = 0.900). Compared with stable plaques, vulnerable plaques had a significantly thinner fibrous cap ((0.58 ± 0.27) mm vs. (0.95 ± 0.22) mm), larger lipid core area ((7.56 ± 2.78) mm(2) vs. (3.29 ± 1.75) mm(2)), and a higher ratio of lipid core area/plaque area ((55 ± 16)% vs. (27 ± 17)%), but plaque area was comparable in two groups on MRI. The ratio of lipid core area/plaque area was a strong predictor of vulnerable plaques.</p><p><b>CONCLUSION</b>MRI could distinguish vulnerable plaques from stable plaques in a rabbit model of atherothrombosis and may thus be useful as a noninvasive modality for detection of vulnerable plaques in humans.</p>
Subject(s)
Animals , Male , Rabbits , Aorta, Abdominal , Pathology , Disease Models, Animal , Magnetic Resonance Imaging , Methods , Plaque, Atherosclerotic , Pathology , Thrombosis , DiagnosisABSTRACT
<p><b>BACKGROUND</b>With features of high tissue contrast, MRI can be used for the qualitative and quantitative evaluation of atherosclerosis plaques. In this study we investigated the development of atherosclerosis plaque with high resolution 3T MRI in a rabbit model and compared the findings with the histopathological results.</p><p><b>METHOD</b>Twenty male New Zealand white rabbits were randomly allocated into an experimental group (n = 16) and a control group (n = 4). Atherosclerotic lesions were induced in the abdominal aorta by balloon injury and cholesterol feeding. Multiple sequences MRI examination (ToF, T1WI, T2WI, and CE T1WI) were performed at the 2nd, 3rd, and 4th months after aortic denudation. Vessel wall thickness, total vessel area, lumen area, and vessel wall area were recorded. Plaque components were analyzed using histological results as a standard reference.</p><p><b>RESULTS</b>Seventeen rabbits (14 in the experimental group and 3 in the control group) received all three MR examinations. Gradually, from 2 months to 4 months, vessel wall thickness and area in the experimental group increased significantly compared with the control group (P < 0.01). In the lumen area progressive stenosis was not found, even a slight dilation had developed in the experimental group. Lipid, fibrotic and calcified plaques can be differentiated by MR image. According to histological results, MRI had good performance in detection of lipid plaque.</p><p><b>CONCLUSION</b>MRI can be used to monitor progression of atherosclerosis and differentiate plaque components.</p>
Subject(s)
Animals , Male , Rabbits , Aorta, Abdominal , Pathology , Magnetic Resonance Imaging , Methods , Plaque, Atherosclerotic , Pathology , Random AllocationABSTRACT
ObjectiveTo investigate the value of 99Tcm labeled survivin mRNA antisense peptide nucleic acid (PNA) as an imaging agent in the specific diagnosis for carcinoma.MethodsSurvivin mRNA antisense PNA was labeled directly with 99Tcm by the ligand-exchange method.Twenty nude mice with lung carcinoma A549 xenografts were randomly divided into 4 groups.Three groups were used for biodistribution study and one group was used for imaging study.Other twenty mice infected by staphylococcus aureus underwent the same procedure.The biodistribution and imaging of 99Tcm-survivin mRNA antisense PNA was studied at 1,2 and 4 h respectively after the intravenous injection in nude mice bearing lung carcinoma A549 xenografts or inflammation models.SPSS 13.0 was used in the study and all data were analyzed by t test.ResultsBiodistribution results showed that the highest radioactivity was found in the liver,and then in the kidney.Four hours after the administration of the imaging agent,the radioactivity ratios of target-tonon target (T/NT,tumor or inflamumatory lesions to the contralateral regions) in tumor model group were significantly higher than those in inflammation model group ( 3.69 ± 1.13 vs 2.03 ± 0.47,t =3.01,P =0.02 ).Tumors were clearly visible in the tumor model groups at 0.5 h and still clearly seen at 4 h after the injection of antisense PNA.On the contrary,inflammatory lesions could not be seen clearly.Conclusion 99Tcm labeled survivin mRNA antisense PNA can be used to distinguish tumor from inflammation and it may provide a new feasible method for specific tumor diagnosis.
ABSTRACT
Objective To prepare the 99Tcm-survivin mRNA antisense peptide nucleic acid (PNA)and investigate its value as a gene imaging agent in tumor bearing mice and early diagnosis in tumor.Methods Survivin mRNA antisense PNA and mismatch PNA were synthesized.Four amino acids (Gly- (D)Ala-Gly-Gly) and Aba (4-aminobutyric acid) were linked to the 5' end of PNA.Gly- (D)Ala-Gly-Gly served as a chelating moiety for strong chelation of 99Tcm and Aba acted as a spacer to minimize the steric hindrance.PNAs were labeled with 99Tcm by the ligand-exchange method.The labeling efficiency and radiochemical purity were measured by HPLC and ITLC methods.There were five BALB/c nude mice bearing human lung carcinoma ( A549 ) in each of antisense PNA and mismatch PNA groups.Gene imaging of 99Tcm-survivin mRNA antisense and mismatch PNAs were performed at 1,2 and 4 h post the injection,respectively,and the T/NT ratio was measured by the method of ROI.The statistical comparisons of average values were performed with the two-group t-test for independent sample by SPSS 13.0.Results The product kept stable in vitro.The labeling efficiency of 99Tcm-survivin mRNA antisense PNA was (95.48 ±1.92)％ and more than 85％ after the incubation for24 h in serum.The radiochemical purity was ＞ 95％.The labeling efficiency of mismatch PNA was similar to the antisense PNA.99Tcm-survivin mRNA antisense PNA was especially uptaken by tumor lesion,and its accumulation reached the top at 4 h post the injection.T/NT ratios at 1,2,and 4 h were 2.70 ± 0.28,3.44 ± 0.35,4.21 ± 0.63,respectively.In the comparison,the T/NT ratio of 99Tcm-survivin mRNA mismatch PNA at 4 h (3.12 ±0.50) was significantly lower (t =2.918,P =0.019).Conclusions 99Tcm-survivin mRNA antisense PNA has high labeling efficiency,good stability and no need of purification.Its characteristic of especial uptake by tumor lesion provides the potential value in early diagnosis of tumor.
ABSTRACT
Objective To evaluate distribution features of disrupted carotid plaque. Methods Forty-three subjects with duplex ultrasound evidence of 50% to 99% stenosis were retrospectively analyzed. Plaques were categorized as disrupted if there was MRI evidence of fibrous cap rupture. Quantity measured areas of the lumen (LA), wall (WA), and plaque components. The morphological parameters used were total vessel area, vessel burden index, eccentricity index. Mann-Whitney test and Chi-square test appropriate used SPSS (v. 12.0 ). Results There were 17 disrupted and 26 undisrupted lesions identified for comparison. Disrupted plaques showed a predominance of longer longitudinal length of large lip nucleus along the vessel wall (6 mm vs. 0 mm, U = 126, P <0.05 ), a large vessel burden (0.67 vs. 0.59, U =105, P <0.05), and high prevalence of thrombus (82.4% vs. 42.3 %, U = 132,P <0.05). In addition, disrupted plaques showed a different pattern of plaque distribution, having a more eccentric position of the lumen (3.68 vs. 2.79, U = 126, P < 0.05 ), a smaller lumen area (23.97 mm2 vs. 30. 18 mm2, U = 138, P<0.05) and a longer segment of stenosis when compared with the intact plaques. Conclusions Disrupted plaques have significantly different characteristics in terms of both axial and longitudinal distribution. A combination of multi-plane and multi-contrast high resolution MRI may provide valuable information about overall lesion morphology and its association to vulnerability.
ABSTRACT
<p><b>OBJECTIVE</b>Left and right ventricular functions were assessed by cine MR imaging in comparison with echocardiography in healthy volunteers.</p><p><b>METHODS</b>A total of 36 healthy volunteers were examined with breath-hold true FISP cine MR imaging sequence and amended localize methods for left and right ventricular functions. Echocardiography (echo) was also performed in these volunteers.</p><p><b>RESULTS</b>(1) left ventricular global function parameters obtained by MR were as follows: EDV (101.3 +/- 19.2) ml, ESV (42.1 +/- 13.3) ml, SV (69.2 +/- 9.8) ml, EF (59.1 +/- 7.2)%; Right ventricular global function as follows: EDV (118.9 +/- 27.1) ml, ESV (57.6 +/- 16.1) ml, SV (61.2 +/- 12.7) ml, EF (51.9 +/- 4.5)%. (2) EDV measured by MR and echo was similar and ESV measured by MR was significantly higher and the rest parameters were lower than that by echo. There was a good correlation (r = 0.66 - 0.80, P < 0.05) on all parameters obtained by MR and echo.</p><p><b>CONCLUSION</b>The present study suggests that cine MR imaging is well applicable to left and right ventricular function and RV volume measurements.</p>
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Echocardiography , Magnetic Resonance Imaging, Cine , Myocardial Contraction , Ventricular Function, Left , Ventricular Function, RightABSTRACT
Objective To study the relationship of MR delayed enhancement with cardiac troponin I in hypertrophic cardiomyopathy(HCM)and to evaluate their values on assessing HCM condition and prognosis.Methods Thirty-five HCM patients who were diagnosed by echocardiography were enrolled.All patients were performed MR scan and cTn Ⅰ test of blood.The relationships of MR delayed enhancement, myocardial hypertrophy and cTn Ⅰ were analyzed.Results(1)DE was found in 25 of total 35 HCM patients(71.4%).19 of 35 HCM patients(54.3%)had abnormal increased eTn Ⅰ value.The medians of cTn Ⅰ in patients with DE and without DE(110,5 ?g/ml,respectively)had statistics significance (P
ABSTRACT
Objective To evaluate the clinical values of(M-slice computed tomography coronary angiography(CTCA) in contrast to conventional coronary angiography(CCA).Methods Assessment of the major and minor branches of coronary arteries by 64-Slice CTCA,showed the information of 100 patients with 64-slice CTCA,comparing with CCA regarded as the golden standard recently implemented.Results Among the 100 patients,920 coronary arteries were evaluated with 370 lesions found.Of them ,348 lesions were consisted with CCA,22 lesions were falsely positive and 10 lesions were found by CCA not picked up by 64-slice CTCA.The sensitivity,specificity,positive predict values and negative predict values were 97.2% ,96%,94% and 98.1% respectively for the detection of coronary artery disease(CAD),Further statistical analysis using a 2-related X~2 test showed no obvious difference in the discovery of CAD between 64-slice CTCA and CCA.Comparing both imaging modalities,there was concordance in assessing lesion severity in 311 lesions,and accuracy approaches 86.8%.Conclusions 64-slice CTCA has excellent sensitivity and specificity in detecting CAD,and also can give fairly accurate assessment of stenosis severity in most patients as compared to CCA.As a alternative method it is a useful non-invasive for detecting coronary arteries disease in symptomatic patients