Atherosclerotic Plaque In MR Imaging Compared With Pathologic Changes And Its Clinic Application

BackgroundDespite advances in our understanding of the pathogenesis of atherosclerosis, cardiovascular diseases are still the leading cause of death in societies. All luminographic techniques, both conventional angiography and magnetic resonance (MR) or computed tomography (CT) angiography, frequently underestimate the true burden of atherosclerosis. The inability of angiography to detect early plaque and to predict plaque rupture has cast a shadow of doubt over the value of this "gold standard" technique. It is well established that the risk of an acute event mediated by plaque rupture is predicated on the composition of the plaque rather than the degree of luminal narrowing. Plaques with a large necrotic lipid core and a thin fibrous cap are associated with a high risk of rupture.The aim of this study is to evaluate atherosclerotic plaque by imaging. There are two parts in our study.Chapter oneDetection of Atherosclerotic Plaque with MRI and Relating Pathologic ChangesPart oneThe Comparison of Two Methods about Dealing with Atherosclerotic Plaque Objective To get better signal-to-noise ratio (SNR), The imaging of atherosclerotic plaque with MRI by two methods were compared in 6 samples. Methods 6 arteries from cut lower limbs were studied. All samples were performed by naked method and dealt method. T1-, T2-weighted and DOUBLEIR T1WI were used in a 1.5-T system ( GE Signa, Twinspeed). CNR (Contrast-to-noise ratio) and SNR were compared in two methods. For T1-, T2-weighted and DOUBLE IR T1WI, parameters such as TR, TE, a field of view of (FOV) ,matrix was better collected.Results CNR between T1-, T2-weighted and DOUBLE IR T1WI in naked methods and dealt methods were significant discrepancy (tTi=36.55, ti2=104.21, tiR=86.85, PO.01). Identically, SNR between T1-, T2-weighted and DOUBLE IR T1WI in naked methods and dealt methods were significant discrepancy (PO.01).Conclusion CNR and SNR by dealt method are superior to ones by naked method. Part twoDetection of Atherosclerotic Plaque with MRI Compared with Pathology Objective The imaging of atherosclerotic plaques with MRI were compared with pathology in 13 samples to get the characterization of plaque morphology in MRI. Methods 13 arteries from cut lower limbs were performed pathologic examination and MRI. T1-, T2-weighted and DOUBLE IR T1WI were performed in a 1.5-T system ( GE Signa, Twinspeed). To maximize signal-to-noise ratio (SNR), a quadrature transmit-receive head neck coil was used. For Tl-,T2-weighted and DOUBLE IR T1WI, parameters such as TR, TE, a field of view of (FOV) ,matrix was better collected. We analyzed three indexes: the degree of luminal stenosis and the components of plaques and the dangerous degree of combining the above two indexes, that were used as a measure of atherosclerotic disease severity. Results1. In the histopathologic findings, the morphology of these plaques was complicated—such plaques were composed of varying amounts of collagen, smooth muscle cells, extracellular lipids, cholesterol monohydrate crystals, thrombus, and calcifications. The components of plaques in MRI compared with pathologic results were complicated. The degree of stenosis of the arteries lumen with MRI was consistent with pathologic results. We accounted that the sensibility of MRI was 98%, the specificity was 100%, and the accuracy ofMRI was 100%.2. Vulnerable lesions are typically described as containing a large necrotic core or intraplaque hemorrhage that is separated from the lumen by an unstable fibrous cap. We defined the unstable plaque that the above component areas exceeded 40% of the all plaque area. In 26 plaques of 13 samples, the unstable plaques account for 81% in pathology and MRI. Identically, we differently accounted the sensibility, specificity, and accuracy of the degree of components of atherosclerotic plagues with MRI was 80%, 98%, 100%.3. Moreover, We weighted the degree of high-risk plaques by adding the degree of arteries luminal narrowing and the areas of vulnerable components. Both in pathology and MRI, the high-risk plaques accounted for 77%. Differently accounted the sensibility, specificity, and accuracy of the dangerous degree of atherosclerotic plagues with MRI was 98%, 100%, 100%.4. CNR between T1-, T2-weighted and DOUBLE IR T1WI ,(3.95 + 0.27, 4.96± 0.34, 8.18 + 0.45 )were significant discrepancy.Conclusion1. This study indicated that the stenosis of artery owing to atherosclerotic plagues can better diagnosed by MRI.2. And by MRI the components of atherosclerotic plagues also can analyzed. Moreover, we could reliably identify the morphologic features of the vulnerable plaque.3. The dangerous degree of atherosclerositic plagues can be used in predicting in stroke and so on.4. DOUBLE IR Tl WI is superior to other sequences. Combined other sequences, the unstable plaques could be better diagnosed.Part threeMorphology of Atherosclerotic Plaque in MRI Compared with Imruuno-histochemistry.Objective The morphology of atherosclerotic plaques with MRI were comparedwith immunohistochemistry in 13 samples to get the characterization of plaque inMRI.Methods 13 arteries from cut lower limbs were performed immunohistochemistryexamination such as CD68, Vimentin and MRI. T1-, T2-weighted and DOUBLE IR T1WI were used in a 1.5-T system ( GE Signa, Twinspeed). For T1-, T2-weighted and DOUBLE IR T1WI, parameters such as TR, TE, a field of view of (FOV) ,matrix was better collected. Compared to immunohistochemistry examination, the components of plaques were analyzed in imaging of MRI. Results1. In 26 plaques of 13 samples, the appearance of CD68, Vimentin was 100% in the histopathologic findings.CD68 could be seen in the bottom or middle of the plaques, Vimentin also could be observed in fibrous caps or middle of the plaques. The components of plaques in MRI compared to pathologic results were complicated. Compared with Vimentin, the appearance of CD68 was not discrepancy in CHI Square, X2=1.733, P=0.188.2. Vulnerable lesions are typically described as containing a large necrotic core or intraplaque hemorrhage that is separated from the lumen by an unstable fibrous cap. We defined the unstable plaque that the above component areas exceeded 40% of the all plaque area, the unstable plaques account for 80% in immunohistochemistry and MRI.Conclusion1. This study indicated that the forming of atherosclerotic plagues is dynamic process in which the quantity of CD68 is not different from the quantity of Vimentin.2. we could reliably identify the morphologic features of the vulnerable plaque.Chapter TwoIdentification of Carotid Atherosclerotic Plaque with MRI andUltrasound and The Relation with the Brain Infarction.Part OneDetection of Carotid Atherosclerotic Plaque with MRI and UltrasoundObjective The morphology of carotid atherosclerotic plaque with MRI werecompared with ultrasound in 30 cases.Methods 30 patients were performed MRI and ultrasound examination. FSET2-weighted, GRE T2WI, 3D PC MRA, DOUBLE IR T1WI were used in a 1.5-Tsystem ( GE Signa Twinspeed). To maximize signal-to-noise ratio (SNR), a quadrature transmit-receive head neck coil was used. For T2-weighted and DOUBLE IR T1WI, parameters such as TR, TE, a field of view of (FOV) ,matrix was better collected. We analyzed three indexes: the degree of luminal stenosis and the components of plaques and the dangerous degree of combining the above two indexes, that were used as a measure of atherosclerotic disease severity. Results1 % In 36 plaques of 30 cases, these plaques were observed between 2 cm of the common carotid bifurcation, 88%(32/36).The features of these plaques in MRI and US extruded from the intima-media of the carotid artery like moon or plate. The measurement of vessel stenosis of artery with MRI was consistent with ultrasound results. We accounted that the sensibility of MRI was 71%.The specificity was 87%. And the accuracy of MRI was 86%.2 > Vulnerable lesions are typically described as containing a large necrotic core or in-traplaque hemorrhage that is separated from the lumen by an unstable fibrous cap. We defined the unstable plaque that the above component areas exceeded 40% of the all plaque area. In 36 plaques of 30 cases, the unstable plaques account for 16% in US and 11% in MRI. Identically, we differently accounted the sensibility, specificity, and accuracy of the degree of components of carotid atherosclerotic plagues with MRI was 80%, 97%, 95%.3> Moreover, We weighted the degree of high-risk plaques by adding the degreeof arteries luminal narrowing and the areas of vulnerable components. Both in USand MRI, the high-risk plaques accounted for 14% and 10%. Differentlyaccounting the sensibility, specificity, and accuracy of the dangerous degree ofatherosclerotic plagues with MRI was 70%, 91%, 92%.4 s CNR between T2-weighted and DOUBLE IR T1WI were significantdiscrepancy.Conclusion1 n This study indicated that the stenosis of artery owing to carotid atheroscleroticplagues can better diagnosised by MRI.2> And by MRI the components of carotid atherosclerotic plagues also cananalyzed. We could reliably identify the morphologic features of the vulnerableplaque.3 > Moreover, the dangerous degree of carotid atherosclerotic plagues can be usedin predicting in stroke.4> Because CNR between T2-weighted and DOUBLE IR T1WI were significantdiscrepancy, DOUBLE IR is superior to other sequences.Part TwoThe Correlation Between Carotid Atherosclerotic Plaque and The BrainInfarction.Objective To detect the correlation between carotid atherosclerotic plaque and thebrain infarction.Methods 30 patients were performed carotid artery and brain examination byMRI. FSE T2-weighted, GRE T2WI, 3D PC MRA, DOUBLE IR T1WI were usedin a 1.5-T system ( GE Signa Twinspeed). To maximize signal-to-noise ratio(SNR), a quadrature transmit-receive head neck coil was used. For T2-weightedand DOUBLE IR T1WI, parameters such as TR, TE, a field of view of(FOV) ,matrix was better collected. We analyzed three indexes: the degree ofluminal stenosis and the components of plaques and the dangerous degree ofcombining the above two indexes, that were used as a measure of atheroscleroticdisease severity. To better analyzing the data, we weighted the numbers of the braininfarction.Results1 -. In 36 plaques of 30 cases, there were 29 infarctions in the brains. The numbersof the plaques and the cases in the I degree of the carotid artery respectivelywere 22, 18; and the numbers of the brain infarction were 14. There was not thebrain infarction in 6 cases of I degree of the carotid artery . The total numbers ofthe plaques and the cases in the II-. Ilk IV degree of the carotid artery respectivelywere 14, 12; and the numbers of the brain infarction were 15. Counting therelation between II > IIL IVdegree of the carotid artery and the brain infarction,Spearman index equaled to 0.823, also Spearman index equaled to 0.344 countingthe relation between I degree of the carotid artery and the brain infarction.2, Vulnerable lesions are typically described as containing a large necrotic core or intraplaque hemorrhage that is separated from the lumen by an unstable fibrous cap.We defined the unstable plaque that the above component areas exceeded 40% of theall plaque area. In 36 plaques of 30 cases, there were 29 infarctions in the brains.The numbers of the unstable plaques account for 11% (4/36), and the numbers of thebrain infarction were 6. The total numbers of the plaques and the cases in thestable carotid plaques respectively were 32, 27; and the numbers of the braininfarction were 23. Counting the relation between unstable plaques and the braininfarction, Spearman index equaled to 0.914, also Spearman index equaled to0.383 counting the relation between stable plaques and the brain infarction.3 -. Moreover, We weighted the degree of high-risk plaques by adding the degreeof arteries luminal narrowing and the areas of vulnerable components. In MRI, thehigh-risk plaques accounted for ll%(4/36). Counting the relation between thehigh-risk plaques and the brain infarction, Spearman index equaled to 0.91.Conclusion1, This study indicated that the stenosis of artery owing to carotid atheroscleroticplagues is well related with the brain infarction.2^ And we could reliably identify the morphologic features of the vulnerableplaque. The unstable plaques are well related with the brain infarction.3^ Moreover, the dangerous degree of carotid atherosclerotic plagues is wellrelated with the brain infarction.