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Canet-Soulas E, Letourneur D. Biomarkers of atherosclerosis and the potential of MRI for the diagnosis of vulnerable plaque. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2007; 20:129-42. [PMID: 17605060 DOI: 10.1007/s10334-007-0078-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 06/04/2007] [Indexed: 12/20/2022]
Abstract
Atherosclerosis is a chronic inflammatory vascular disease. As it is an inflammation process, many cellular and molecular events are involved at each step of the progression of atherosclerosis from an early fatty streak lesion to a highly dangerous rupture-prone plaque. Magnetic resonance imaging (MRI) is a well-established diagnostic tool for many kinds of chronic inflammation in various systems and organs, and recent improvements in spatial resolution and contrast strategies make it a promising technique for the characterization of inflammatory vessel walls. The first part of this review will briefly introduce the main cellular and molecular processes involved in atherosclerotic lesions; the second part will focus on the use of high-resolution MRI and present-generation contrast agents for plaque characterization; and the third part will present some recent and ongoing cellular and molecular MRI studies of atherosclerosis.
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Affiliation(s)
- E Canet-Soulas
- Université Lyon 1, ESCPE, Laboratoire CREATIS-LRMN, CNRS UMR 5220, INSERM U630, Domaine Scientifique de la Doua, 43 Bd 11 novembre 1918, 69622 Villeurbanne Cedex, France.
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52
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Sun B, Giddens DP, Long R, Taylor WR, Weiss D, Joseph G, Vega D, Oshinski JN. Characterization of coronary atherosclerotic plaque using multicontrast MRI acquired under simulated in vivo conditions. J Magn Reson Imaging 2007; 24:833-41. [PMID: 16929530 DOI: 10.1002/jmri.20687] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To compare coronary atherosclerotic plaque characterization using multicontrast MRI on: 1) freshly excised vessels under simulated in vivo conditions, and 2) preserved vessels. MATERIALS AND METHODS T1-weighted (T1W), T2-weighted (T2W), proton density-weighted (PDW), and diffusion-weighted (DW) MR images were acquired on 13 freshly excised human coronary arteries from explanted hearts. Vessels were imaged in an MR-compatible tissue culture chamber using a 4.7 Tesla small-bore MR scanner. Eight vessels were then preserved in buffered formalin and rescanned following the same imaging protocol. A three-dimensional spatially penalized fuzzy C-means (3D-SPFCM) technique was applied to classify different plaque constituents. The classification results from vessels under "fresh" and "preserved" conditions were compared with corresponding histological sections. RESULTS For most plaque constituents, the plaque characterization results show no significant difference between fresh and preserved scans, and little difference between scans and the histological reference standard. In the case of thrombus, apparent signal changes between fresh and preserved images were identified. Overall, MR scans conducted under preserved conditions provided a 1.8% to 17.5% greater signal-to-noise ratio (SNR) than those conducted in the fresh stage. CONCLUSION Preservation of coronary vessels did not alter the contrast between plaque tissues on multicontrast MRI, and did not significantly change the results of plaque constituent characterization.
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Affiliation(s)
- Binjian Sun
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30322, USA
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53
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Magnetic Resonance Angiography and Evaluation of Vulnerable Plaque. CARDIOVASCULAR MEDICINE 2007. [DOI: 10.1007/978-1-84628-715-2_40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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54
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Trocciola SM, Dayal R, Chaer RA, Lin SC, DeRubertis B, Ryer EJ, Hynececk RL, Pierce MJ, Prince M, Badimon J, Marin ML, Fuster V, Kent KC, Faries PL. The development of endotension is associated with increased transmission of pressure and serous components in porous expanded polytetrafluoroethylene stent-grafts: Characterization using a canine model. J Vasc Surg 2006; 43:109-16. [PMID: 16414397 DOI: 10.1016/j.jvs.2005.09.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Accepted: 09/13/2005] [Indexed: 11/29/2022]
Abstract
OBJECTIVE This study used a canine model of abdominal aortic aneurysms (AAAs) to compare intra-aneurysmal pressure and thrombus formation after exclusion with Dacron and expanded polytetrafluoroethylene (ePTFE) stent-grafts. METHODS Prosthetic AAAs with implanted strain-gauge pressure transducers were treated by stent-graft exclusion using Food and Drug Administration-approved devices in 10 mongrel dogs: five Dacron (AneuRx) and five ePTFE (original Excluder). Intra-aneurysmal pressure was measured over 4 weeks after AAA exclusion and indexed to the systemic pressure, represented as a percentage of a simultaneously obtained systemic pressure (value = 1.0). Magnetic resonance imaging (MRI) of the intra-aneurysmal thrombus was performed at 1, 2, and 4 weeks after exclusion and expressed as a signal-to-noise ratio (S:N) to control for background signal intensity. Comparisons of pressures and S:N between the two stent-grafts was analyzed with the Student's t test. Intra-aneurysmal thrombus was characterized histologically. RESULTS In animals excluded with both Dacron and ePTFE stent-grafts, the intra-aneurysmal pressure was nonpulsatile and reduced to <30% of systemic pressure. Significantly greater pressure transmission was observed after AAA exclusion using ePTFE compared with Dacron stent grafts (systolic pressure: ePTFE, 0.28 +/- 0.12 vs Dacron, 0.11 +/- 0.02, P < .001; mean pressure: ePTFE, 0.16 +/- 0.08 vs Dacron, 0.06 +/- 0.02, P < .001). MRI confirmed the absence of perfusion in all aneurysms. The T1-weighted signal intensity remained persistently elevated (S:N at 1 week, 2.7 +/- 0.4 vs 2 weeks, 4.0 +/- 0.2 vs 4 weeks, 5.4 +/- 1.3) in ePTFE-treated intra-aneurysmal thrombus, suggesting an absence of thrombus organization. In contrast, progressive evolution of T1 signal intensity in aneurysms excluded by Dacron stent-grafts was consistent with maturation from intact red blood cells (S:N at 1 week, 3.3 +/- 0.4) to methemoglobin (S:N at 2 weeks, 6.1 +/- 0.8), and then hemosiderin and ferritin (S:N at 4 weeks, 2.4 +/- 0.5). Histologically, ePTFE-excluded aneurysms contained poorly organized thrombus with red blood cell fragments and haphazardly arranged fibrin deposition indicative of active remodeling and continued influx of transudated serum. In aneurysms excluded by Dacron stent-grafts, dense, mature collagenous connective tissue and organized fibrin were present, indicative of greater thrombus organization. CONCLUSIONS Stent-graft treatment reduces intra-aneurysmal pressure to <30% of systemic pressure when no endoleak is present; however, significantly greater pressure is present in aneurysms treated with porous ePTFE stent-grafts than Dacron grafts. Histologic and MRI imaging analysis suggest that active transudation of serous blood components may be contributing to this increased intra-aneurysmal pressure.
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Affiliation(s)
- Susan M Trocciola
- Department of Surgery, New York Presbyterian Hospital, Cornell University, New York, NY 10021, USA
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Pedrosa I, Morrin M, Oleaga L, Baptista J, Rofsky NM. Is True FISP Imaging Reliable in the Evaluation of Venous Thrombosis? AJR Am J Roentgenol 2005; 185:1632-40. [PMID: 16304026 DOI: 10.2214/ajr.04.1323] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of our study was to evaluate the accuracy of true fast imaging with steady-state precession (FISP) in the diagnosis of venous thrombosis using gadolinium-enhanced 3D T1-weighted gradient-echo images and correlative imaging as the gold standard. MATERIALS AND METHODS Twenty-five MR examinations were retrospectively reviewed independently by two radiologists to rule out thrombosis in the central veins of the body. The presence of venous thrombus was assessed separately in 80 veins using true FISP and gadolinium-enhanced T1-weighted images. Diagnosis was confirmed by another imaging technique (sonography, CT, and/or conventional venography) in all positive cases. Negative examinations were confirmed using imaging, clinical follow-up, or both. RESULTS Venous thrombosis was present in 25 veins in 18 patients. True FISP images had a lower sensitivity (66%) and specificity (70.9%) for the diagnosis of venous thrombosis than gadolinium-enhanced MR images (p < 0.01). CONCLUSION True FISP images have lower sensitivity and specificity in the diagnosis of venous thrombosis than gadolinium-enhanced T1-weighted gradient-echo images. True FISP images should not be used exclusively for the diagnosis of venous thrombosis.
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Affiliation(s)
- Ivan Pedrosa
- Department of Radiology, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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56
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Nighoghossian N, Derex L, Douek P. The vulnerable carotid artery plaque: current imaging methods and new perspectives. Stroke 2005; 36:2764-72. [PMID: 16282537 DOI: 10.1161/01.str.0000190895.51934.43] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Atherosclerosis is a diffuse, chronic inflammatory disorder that involves the vascular, metabolic, and immune systems and leads to plaque vulnerability. The traditional risk assessment relies on clinical, biological, and conventional imaging tools. However, these tools fall short in predicting near-future events in patients with vulnerable carotid artery plaque. METHODS In current clinical practice, anatomic imaging modalities, such as B-mode ultrasound, spiral computed tomography angiography, and high-resolution MRI, can identify several morphological features characteristic of the vulnerable plaque but give little or no information regarding molecular and cellular mechanisms. RESULTS This review is dedicated to factors involved in carotid artery plaque vulnerability and to new imaging methods that target this condition. Our aim is to describe the following: (1) conventional pathologic and imaging markers predictive of plaque vulnerability; (2) the role of relevant biological, genetic, and mechanical factors; (3) the potential of new imaging methods; and (4) current and emerging treatments. CONCLUSIONS A multimodal assessment of plaque vulnerability involving the combination of systemic markers, new imaging methods that target inflammatory and thrombotic components, and the potential of emerging therapies may lead to a new stratification system for atherothrombotic risk and to a better prevention of atherothrombotic stroke.
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Sirol M, Fuster V, Badimon JJ, Fallon JT, Moreno PR, Toussaint JF, Fayad ZA. Chronic Thrombus Detection With In Vivo Magnetic Resonance Imaging and a Fibrin-Targeted Contrast Agent. Circulation 2005; 112:1594-600. [PMID: 16145001 DOI: 10.1161/circulationaha.104.522110] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Arterial thrombosis plays a critical role in acute coronary syndromes and stroke. Therefore, the ability to detect thrombus in vivo has a significant clinical implication. Magnetic resonance imaging (MRI) has shown promise in noninvasive thrombus detection. However, thrombus characterization and age definition remain difficult. We sought to evaluate the use of a fibrin-targeted peptide (EP-2104R) for MR thrombus detection and to compare this modality with non–contrast-enhanced (NCE) MRI and with Gd-DTPA injection at various ages and time points after thrombus generation.
Methods and Results—
Carotid artery thrombosis was induced by external injury and stasis in 18 rabbits. T1-weighted MRI was performed before and after contrast agent injection, within 6 hours of thrombus induction, at 48 hours, at 1 week, and every week up to 8 weeks after injury. Correlation with histopathology was performed. The fibrin-targeted contrast agent accurately detected all thrombi, regardless of their size, location, and age. Although thrombus signal intensity after injection decreased with thrombus age (
P
<0.001), enhancement at 8 weeks was still present. Gd-DTPA injection was not associated with an improvement of thrombus detection. EP-2104R was superior to both NCE and Gd-DTPA injection (
P
<0.001). Histopathologic examination showed thrombus organization over time. Fibrin was gradually replaced by fibrous tissue. A strong correlation was found between thrombus enhancement and collagen content of the organizing thrombus with time (
R
=−0.89;
P
<0.001).
Conclusions—
In an experimental animal model of carotid thrombosis, we have demonstrated the superiority of a fibrin-targeted MR contrast agent for in vivo detection of chronic or organized thrombus, compared with NCE MRI and Gd-DTPA injection.
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Affiliation(s)
- Marc Sirol
- Department of Cardiology, Hôpital Lariboisière, Paris, France
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Sirol M, Aguinaldo JGS, Graham PB, Weisskoff R, Lauffer R, Mizsei G, Chereshnev I, Fallon JT, Reis E, Fuster V, Toussaint JF, Fayad ZA. Fibrin-targeted contrast agent for improvement of in vivo acute thrombus detection with magnetic resonance imaging. Atherosclerosis 2005; 182:79-85. [PMID: 16115477 DOI: 10.1016/j.atherosclerosis.2005.02.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 01/28/2005] [Accepted: 02/09/2005] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Plaque rupture leading to thrombosis and occlusion is a major source of acute coronary syndromes. Methods for accurate detection of thrombosis in veins or arteries may expand our capacity to predict clinical complications and guide therapeutic decisions. We sought to demonstrate the feasibility of in vivo acute thrombus detection using a fibrin-targeted gadolinium based magnetic resonance contrast agent (EP-1242). METHODS Carotid thrombosis was induced in 12 guinea pigs by external injury and blood stasis. MR images were obtained after thrombus formation pre- and post- EP-1242 injection, using a T1-weighted high-resolution fast spin-echo sequence. RESULTS An occlusive fibrin-rich thrombus was achieved in all animals. Correlation for thrombus location was excellent between MRI and histology (R=0.94; P<0.001). Contrast-enhanced MRI significantly improved thrombus detection when compared to non contrast-enhanced MRI (100% versus 41.6%; p<0.001). In addition, thrombus signal intensity (SI) was significantly increased after injection (SI(30 min-post)=4.39+/-0.12 versus 1.0; p<0.001). Contrast-to-noise ratio (CNR) was 43.8+/-7.2, 30 min post-injection (P<0.001). No enhancement was seen in the uninjured control arteries. CONCLUSIONS We demonstrate the feasibility of in vivo MRI for carotid thrombus detection using a novel fibrin-targeted contrast agent. This technique significantly improves detection of small size thrombi in an animal model of occlusive fibrin-rich thrombosis.
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Affiliation(s)
- Marc Sirol
- Department of Cardiology, Hôpital Lariboisière, Paris, France
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Boll DT, Merkle EM, Lewin JS. MR-Guided Percutaneous Sclerotherapy of Low-Flow Vascular Malformations in the Head and Neck. Magn Reson Imaging Clin N Am 2005; 13:595-600. [PMID: 16084422 DOI: 10.1016/j.mric.2005.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
MR-guided sclerotherapy is an excellent approach for the treatment of the predominant symptoms of congenital low-flow vascular malformations in the head and neck. In the authors' experience, this mode of treatment appears to be safe and efficient and allows the quantitative verification of therapeutic success during follow-up examinations.
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Affiliation(s)
- Daniel T Boll
- Department of Radiology, University Hospitals of Ulm, Steinhövelstrasse 9, 89075 Ulm, Germany
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60
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Spuentrup E, Fausten B, Kinzel S, Wiethoff AJ, Botnar RM, Graham PB, Haller S, Katoh M, Parsons EC, Manning WJ, Busch T, Günther RW, Buecker A. Molecular magnetic resonance imaging of atrial clots in a swine model. Circulation 2005; 112:396-9. [PMID: 16009790 DOI: 10.1161/circulationaha.104.529941] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND The detection and differentiation of intracardiac masses is still challenging and may include neoplasms and thrombi. The aim of this study was the investigation of a targeted, fibrin-specific contrast agent (EP-2104R) for molecular targeted magnetic resonance imaging (MRI) of left atrial clots. METHODS AND RESULTS Chronic human thrombi were surgically implanted in the left atrial appendage of 5 swine. Molecular MRI was performed with a navigator-gated, free-breathing, cardiac-triggered 3D inversion-recovery, black-blood, gradient-echo sequence before and after systemic administration of 4 micromol/kg EP-2104R. MR images were analyzed by 2 investigators, and the contrast-to-noise ratio was calculated. Location of clots was confirmed by autopsy, and the gadolinium concentration in the clots was assessed. Before contrast agent administration, thrombi were not visible on black-blood MR images. After contrast administration, all atrial clots (n=5) were selectively visualized as white spots with a high contrast-to-noise ratio (clot/blood, 29.7+/-8.0). The gadolinium concentration in the clots averaged 74+/-45 micromol/L. CONCLUSIONS The fibrin-specific MR contrast agent EP-2104R allows for selective and high-contrast visualization of left atrial clots by means of molecular targeted MRI.
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Affiliation(s)
- Elmar Spuentrup
- Department of Diagnostic Radiology, Aachen Technical University, Aachen, Germany.
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61
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Spuentrup E, Katoh M, Wiethoff AJ, Parsons EC, Botnar RM, Mahnken AH, Günther RW, Buecker A. Molecular magnetic resonance imaging of pulmonary emboli with a fibrin-specific contrast agent. Am J Respir Crit Care Med 2005; 172:494-500. [PMID: 15937292 DOI: 10.1164/rccm.200503-379oc] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE AND OBJECTIVES The detection of pulmonary embolism is still challenging due to the often nonspecific clinical findings. The aim of this study was to investigate the potential of molecular targeted magnetic resonance imaging (MRI) of pulmonary emboli using low-dose application of a fibrin-specific contrast agent (EP-2104R; Epix Pharmaceuticals, Cambridge, MA). METHODS Fresh clots from human blood were engineered ex vivo and delivered in the lungs of 11 swine. Subsequently, a T1-weighted breath-hold three-dimensional gradient-echo sequence was performed before as well as 5 minutes, 1 hour, and 2 hours after systemic administration of 7.5 (n = 5) or 4 (n = 5) micromol/kg EP-2104R. One swine that did not receive any contrast agent served as a control. MR images were analyzed by two investigators and contrast-to-noise ratio between the thrombus and the surrounding tissue (blood pool and lung parenchyma) was assessed. Localization of thrombi was compared with 16-row multislice computed tomography. Finally, the animals were killed and thrombi were removed for assessment of gadolinium concentration. MAIN RESULTS Before contrast media application, thrombi were not visible on MR images. At 1 and 2 hours after contrast media injection, pulmonary emboli were selectively visualized with high-signal intensity foci, independent of the dosage used. A high gadolinium concentration in thrombi was found after both dosages (83 +/- 41 microM for 4 micromol/kg and 130 +/- 57microM for 7.5 micromol/kg), resulting in a similar high contrast-to-noise ratio on MR images (between 11 and 13). CONCLUSION Systemic low-dose application of EP-2104R allows for selective molecular MRI of fresh pulmonary thromboembolism in a swine model.
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Affiliation(s)
- Elmar Spuentrup
- Department of Diagnostic Radiology, University Hospital, Aachen Technical University, Pauwelsstrasse 30, 52057 Aachen, Germany.
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Kim WY, Spuentrup E, Buecker A, Manning WJ, Botnar RM. Cardiovascular magnetic resonance imaging of coronary atherothrombosis. J Nucl Cardiol 2005; 12:337-44. [PMID: 15944539 DOI: 10.1016/j.nuclcard.2005.03.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- W Yong Kim
- MR-Center, Institute of Clinical Medicine, Aarhus University Hospital, Skejby Sygehus, Denmark.
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Corti R, Badimon J, Mizsei G, Macaluso F, Lee M, Licato P, Viles-Gonzalez JF, Fuster V, Sherman W. Real time magnetic resonance guided endomyocardial local delivery. Heart 2005; 91:348-53. [PMID: 15710717 PMCID: PMC1768781 DOI: 10.1136/hrt.2004.034363] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVE To investigate the feasibility of targeting various areas of left ventricle myocardium under real time magnetic resonance (MR) imaging with a customised injection catheter equipped with a miniaturised coil. DESIGN A needle injection catheter with a mounted resonant solenoid circuit (coil) at its tip was designed and constructed. A 1.5 T MR scanner with customised real time sequence combined with in-room scan running capabilities was used. With this system, various myocardial areas within the left ventricle were targeted and injected with a gadolinium-diethylenetriaminepentaacetic acid (DTPA) and Indian ink mixture. RESULTS Real time sequencing at 10 frames/s allowed clear visualisation of the moving catheter and its transit through the aorta into the ventricle, as well as targeting of all ventricle wall segments without further image enhancement techniques. All injections were visualised by real time MR imaging and verified by gross pathology. CONCLUSION The tracking device allowed real time in vivo visualisation of catheters in the aorta and left ventricle as well as precise targeting of myocardial areas. The use of this real time catheter tracking may enable precise and adequate delivery of agents for tissue regeneration.
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Affiliation(s)
- R Corti
- Cardiovascular Biology Research Laboratory, Mount Sinai School of Medicine, New York, New York 10029, USA
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64
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Spuentrup E, Buecker A, Katoh M, Wiethoff AJ, Parsons EC, Botnar RM, Weisskoff RM, Graham PB, Manning WJ, Günther RW. Molecular magnetic resonance imaging of coronary thrombosis and pulmonary emboli with a novel fibrin-targeted contrast agent. Circulation 2005; 111:1377-82. [PMID: 15738354 DOI: 10.1161/01.cir.0000158478.29668.9b] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The differential diagnosis of acute chest pain is challenging, especially in patients with normal ECG findings, and may include coronary thrombosis or pulmonary emboli. The aim of this study was to investigate the novel fibrin-specific contrast agent EP-2104R for molecular targeted MR imaging of coronary thrombosis and pulmonary emboli. METHODS AND RESULTS Fresh clots were engineered ex vivo from human blood and delivered in the lungs and coronary arteries of 7 swine. Subsequent molecular MR imaging was performed with a navigator-gated free-breathing and cardiac-triggered 3D inversion-recovery black-blood gradient-echo sequence before and after systemic administration of 7.5 micromol/kg EP-2104R. Two swine served as the control group. MR images were analyzed by 2 investigators, and contrast-to-noise ratio and gadolinium concentration in the clots were assessed. Before contrast media application, no thrombi were visible. After contrast administration, all 32 pulmonary emboli, 3 emboli in the right heart, and 5 coronary thrombi were selectively visualized as white spots with a mean contrast-to-noise ratio of 32+/-19. The average gadolinium concentration from all 3 types of thrombi was 144+/-79 micromol/L. CONCLUSIONS Molecular MR imaging with the fibrin-targeted contrast-agent EP-2104R allows selective visualization of acute coronary, cardiac, and pulmonary thrombi.
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Affiliation(s)
- Elmar Spuentrup
- Department of Diagnostic Radiology, University Hospital, Aachen Technical University, Aachen, Germany.
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Viereck J, Ruberg FL, Qiao Y, Perez AS, Detwiller K, Johnstone M, Hamilton JA. MRI of atherothrombosis associated with plaque rupture. Arterioscler Thromb Vasc Biol 2004; 25:240-5. [PMID: 15528478 DOI: 10.1161/01.atv.0000149673.00564.0a] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE MRI would be a valuable noninvasive diagnostic tool to study plaque-associated thrombi. We defined the imaging characteristics of these thrombi, composed primarily of platelets and fibrin, and distinguished them clearly from the vessel lumen and underlying atherosclerotic plaque in an animal model of plaque rupture. METHODS AND RESULTS After triggering plaque rupture in New Zealand White male rabbits, segments of infrarenal aorta containing either red or white thrombi were fixed in formalin. Compared with postmortem red cell-rich thrombi, atherothrombi yielded complex magnetic resonance images with intermediate signal intensity in standard T1- and T2-weighted imaging sequences and were often difficult to distinguish from the aortic wall. Diffusion-weighted imaging sequences revealed restricted diffusion of the atherothrombus relative to the vessel wall and provided excellent contrast. The apparent diffusion coefficient of the thrombus is 1.0x10(-3) mm2/s, compared with 1.5x10(-3) mm2/s in tissue. Similar results were obtained using purified aggregated platelets. CONCLUSIONS We present the first detailed description of the MRI appearance of plaque rupture-associated thrombosis in histologically validated platelet-rich thrombi. Diffusion-weighted imaging provided the best distinction between thrombus and vessel wall and has potential application for the noninvasive in vivo detection of atherothrombosis.
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Affiliation(s)
- Jason Viereck
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
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66
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Boll DT, Merkle EM, Lewin JS. Low-Flow Vascular Malformations: MR-guided Percutaneous Sclerotherapy in Qualitative and Quantitative Assessment of Therapy and Outcome. Radiology 2004; 233:376-84. [PMID: 15516614 DOI: 10.1148/radiol.2332031213] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To prospectively assess the therapeutic procedure and outcome of magnetic resonance (MR)-guided percutaneous sclerotherapy in patients with low-flow vascular malformations. MATERIALS AND METHODS Seventy-six percutaneous sclerotherapy treatments were performed by one radiologist with real-time MR guidance in 15 patients (six female patients; mean age, 54.4 years +/- 11.1; nine male patients; mean age, 32.9 years +/- 14.1) with vascular malformations in the head and neck (n = 64), spine (n = 5), and extremities (n = 7). Qualitative assessment was used to analyze (a) individual success of therapy, (b) occurrence of complications, (c) time required for minimally invasive MR-guided sclerotherapy in regression analysis, (d) ability of MR imaging to depict postinterventional perfusion changes within the vascular malformation with calculation of changes in contrast-to-noise ratios, and (e) detection of volume changes at follow-up examinations with volumetric analysis. RESULTS Percutaneous sclerotherapy was performed successfully and without complications by filling targeted vascular malformations with sclerosing agent. Induced vascular sclerosis was used to successfully treat individual predominant symptoms, such as hemorrhage, pain, cosmetic disfigurement, and functional impairment. Quantitative analysis focusing on the actual interventional length of time presented an acceleration over the 5-year time period, matching a cubic function in regression curve fit and taking 31 minutes 50 seconds +/- 14 minutes. Induced vascular thrombosis was identified in all treated portions on postinterventional images by the statistically significant changes in contrast-to-noise ratio (P < .05) compared with preinterventional imaging. On follow-up images (ie, those obtained after 12 weeks +/- 6), shrinkage was observed in targeted portions (67.2% +/- 18.9). CONCLUSION MR imaging allows safe guidance and monitoring of minimally invasive sclerotherapy and permits verification of therapeutic success postinterventionally and during follow-up examinations.
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Affiliation(s)
- Daniel T Boll
- Department of Radiology, University Hospitals of Cleveland, Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH 44106-5056, USA
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Botnar RM, Buecker A, Wiethoff AJ, Parsons EC, Katoh M, Katsimaglis G, Weisskoff RM, Lauffer RB, Graham PB, Gunther RW, Manning WJ, Spuentrup E. In vivo magnetic resonance imaging of coronary thrombosis using a fibrin-binding molecular magnetic resonance contrast agent. Circulation 2004; 110:1463-6. [PMID: 15238457 DOI: 10.1161/01.cir.0000134960.31304.87] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND The advent of fibrin-binding molecular magnetic resonance (MR) contrast agents and advances in coronary MRI techniques offers the potential for direct imaging of coronary thrombosis. We tested the feasibility of this approach using a gadolinium (Gd)-based fibrin-binding contrast agent, EP-2104R (EPIX Medical Inc), in a swine model of coronary thrombus and in-stent thrombosis. METHODS AND RESULTS Ex vivo and in vivo sensitivity of coronary MR thrombus imaging was tested by use of intracoronarily delivered Gd-DTPA-labeled fibrinogen thrombi (n=6). After successful demonstration, in-stent coronary thrombosis was induced by x-ray-guided placement of thrombogenic-coated, MR-lucent stents (n=5). After stent placement, 60 micromol of EP-2104R was injected via the left main coronary artery. Free-breathing, navigator-gated 3D coronary MR angiography and thrombus imaging were performed (1) before and after stent placement and (2) before and after EP-2104R. Thrombi were confirmed by x-ray angiography and autopsy. Fibrinogen thrombi: 5 of 6 intracoronarily delivered Gd-labeled fibrinogen clots (approximately 250 micromol/L Gd) were visible on MRI and subsequently confirmed by x-ray angiography. In-stent thrombi: in-stent thrombosis was observed in all stents after EP-2104R. Four of 5 thrombi were confirmed by x-ray angiography. Chemical analysis of 2 thrombi demonstrated 99 to 147 micromol/L Gd. CONCLUSIONS We demonstrate the feasibility of MRI of coronary thrombus and in-stent thrombosis using a novel fibrin-binding molecular MR contrast agent. Potential applications include detection of coronary in-stent thrombosis or thrombus burden in patients with acute coronary syndromes.
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Affiliation(s)
- René M Botnar
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Mass 02215, USA.
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Botnar RM, Perez AS, Witte S, Wiethoff AJ, Laredo J, Hamilton J, Quist W, Parsons EC, Vaidya A, Kolodziej A, Barrett JA, Graham PB, Weisskoff RM, Manning WJ, Johnstone MT. In vivo molecular imaging of acute and subacute thrombosis using a fibrin-binding magnetic resonance imaging contrast agent. Circulation 2004; 109:2023-9. [PMID: 15066940 PMCID: PMC2910574 DOI: 10.1161/01.cir.0000127034.50006.c0] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Plaque rupture with subsequent thrombosis is recognized as the underlying pathophysiology of most acute coronary syndromes and stroke. Thus, direct thrombus visualization may be beneficial for both diagnosis and guidance of therapy. We sought to test the feasibility of direct imaging of acute and subacute thrombosis using MRI together with a novel fibrin-binding gadolinium-labeled peptide, EP-1873, in an experimental animal model of plaque rupture and thrombosis. METHODS AND RESULTS Fifteen male New Zealand White rabbits (weight, approximately 3.5 kg) were made atherosclerotic by feeding a high-cholesterol diet after endothelial aortic injury. Plaque rupture was then induced with the use of Russell's viper venom (RVV) and histamine. Subsequently, MRI of the subrenal aorta was performed before RVV, after RVV, and after EP-1873. Histology was performed on regions suggested by MRI to contain thrombus. Nine rabbits (60%) developed plaque rupture and thrombus, including 25 thrombi visually apparent on MRI as "hot spots" after injection of EP-1873. Histological correlation confirmed all 25 thrombi (100%), with no thrombi seen in the other regions of the aorta. In the remaining 6 rabbits (control) without plaque rupture, no thrombus was observed on the MR images or on histology. CONCLUSIONS We demonstrate the feasibility of in vivo "molecular" MRI for the detection of acute and subacute thrombosis using a novel fibrin-binding MRI contrast agent in an animal model of atherosclerosis and acute/subacute thrombosis. Potential clinical applications include thrombus detection in acute coronary syndromes and stroke.
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Affiliation(s)
- René M Botnar
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Mass, USA
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Chu B, Kampschulte A, Ferguson MS, Kerwin WS, Yarnykh VL, O'Brien KD, Polissar NL, Hatsukami TS, Yuan C. Hemorrhage in the atherosclerotic carotid plaque: a high-resolution MRI study. Stroke 2004; 35:1079-84. [PMID: 15060318 DOI: 10.1161/01.str.0000125856.25309.86] [Citation(s) in RCA: 323] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE High-resolution, multicontrast magnetic resonance imaging (MRI) has developed into an effective tool for the identification of carotid atherosclerotic plaque components, such as necrotic core, fibrous matrix, and hemorrhage/thrombus. Factors that may lead to plaque instability are lipid content, thin fibrous cap, and intraplaque hemorrhage. Determining the age of intraplaque hemorrhage can give insight to the history and current condition of the biologically active plaque. The aim of this study was to develop criteria for the identification of the stages of intraplaque hemorrhage using high-resolution MRI. METHODS Twenty-seven patients, scheduled for carotid endarterectomy (CEA), were imaged on a 1.5-T GE SIGNA scanner (sequences: 3-dimensional time of flight, double-inversion recovery, T1-weighted (T1W), PDW and T2W). Two readers, blinded to histology, reviewed MR images and grouped hemorrhage into fresh, recent, and old categories using a modified cerebral hemorrhage criteria. The CEA specimens were serially sectioned and graded as to presence and stage of hemorrhage. RESULTS Hemorrhage was histologically identified and staged in 145/189 (77%) of carotid artery plaque locations. MRI detected intraplaque hemorrhage with high sensitivity (90%) but moderate specificity (74%). Moderate agreement in classifying stages occurred between MRI and histology (Cohen kappa=0.7, 95% CI: 0.5 to 0.8 for reviewer 1 and 0.4, 95% CI: 0.2 to 0.6 for reviewer 2), with moderate agreement between the 2 MRI readers (kappa=0.4, 95% CI: 0.3 to 0.6). CONCLUSIONS Multicontrast MRI can detect and classify carotid intraplaque hemorrhage with high sensitivity and moderate specificity.
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Affiliation(s)
- Baocheng Chu
- Department of Radiology, University of Washington, USA
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Kramer CM, Cerilli LA, Hagspiel K, DiMaria JM, Epstein FH, Kern JA. Magnetic resonance imaging identifies the fibrous cap in atherosclerotic abdominal aortic aneurysm. Circulation 2004; 109:1016-21. [PMID: 14967731 PMCID: PMC2957882 DOI: 10.1161/01.cir.0000116767.95046.c2] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND MRI can distinguish components of atherosclerotic plaque. We hypothesized that contrast enhancement with gadolinium-DTPA (Gd-DTPA) could aid in the differentiation of plaque components in abdominal aortic aneurysm (AAA). METHODS AND RESULTS Twenty-three patients (19 males, age 70+/-8 years) with AAA underwent MRI on a 1.5-T clinical scanner 3+/-3 days before surgical grafting. T1- and T2-weighted (W) black blood spin echo imaging was performed in 1 axial slice, and the T1-W imaging was repeated after a Gd-DTPA-enhanced 3D magnetic resonance angiogram. A section of the aorta at the site of imaging was resected at surgery for histopathologic examination of tissue components and inflammatory cells. Signal-to-noise and contrast-to-noise ratios (CNR) were measured in visualized plaque components from multispectral MRI, and percent enhancement after contrast on T1-W imaging was calculated. The kappa value for agreement between pathology and MRI for the number of tissue components was 0.785. T2-W imaging identified thrombus as regions of high signal and lipid core as low signal, with a CNR of 6.43+/-3.41. Nine patients had a fibrous cap pathologically, which was visualized as a discrete area of uniform increased signal on T2-W imaging with a CNR of 4.52+/-1.93 compared with lipid core. Within the cap, the percent enhancement after Gd-DTPA on T1-W imaging was 91+/-63%. CONCLUSIONS Higher signal on T2-W MRI identifies the fibrous cap and thrombus within AAA. Contrast enhancement improves delineation of the fibrous cap. The addition of contrast to MRI plaque imaging may enhance identification of vulnerable plaque.
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Affiliation(s)
- Christopher M Kramer
- Department of Radiology, University of Virginia Health System, Lee Street, Box 800170, Charlottesville, VA 22908, USA.
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71
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Cappendijk VC, Cleutjens KBJM, Heeneman S, Schurink GWH, Welten RJTJ, Kessels AGH, van Suylen RJ, Daemen MJAP, van Engelshoven JMA, Kooi ME. In vivo detection of hemorrhage in human atherosclerotic plaques with magnetic resonance imaging. J Magn Reson Imaging 2004; 20:105-10. [PMID: 15221815 DOI: 10.1002/jmri.20060] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
PURPOSE To investigate the performance of high-resolution T1-weighted (T1w) turbo field echo (TFE) magnetic resonance imaging (MRI) for the identification of the high-risk component intraplaque hemorrhage, which is described in the literature as a troublesome component to detect. MATERIALS AND METHODS An MRI scan was performed preoperatively on 11 patients who underwent carotid endarterectomy because of symptomatic carotid disease with a stenosis larger than 70%. A commonly used double inversion recovery (DIR) T1w turbo spin echo (TSE) served as the T1w control for the T1w TFE pulse sequence. The MR images were matched slice by slice with histology, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the MR images were calculated. Additionally, two readers, who were blinded for the histological results, independently assessed the MR slices concerning the presence of intraplaque hemorrhage. RESULTS More than 80% of the histological proven intraplaque hemorrhage could be detected using the TFE sequence with a high interobserver agreement (Kappa = 0.73). The TFE sequence proved to be superior to the TSE sequence concerning SNR and CNR, but also in the qualitative detection of intraplaque hemorrhage. The false positive TFE results contained fibrous tissue and were all located outside the main plaque area. CONCLUSION The present study shows that in vivo high-resolution T1w TFE MRI can identify the high-risk component intraplaque hemorrhage with a high detection rate in patients with symptomatic carotid disease. Larger clinical trials are warranted to investigate whether this technique can identify patients at risk for an ischemic attack.
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Affiliation(s)
- Vincent C Cappendijk
- Department of Radiology, Cardiovascular Research Institute Maastricht (CARIM), University Hospital of Maastricht, The Netherlands
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Naghavi M, Libby P, Falk E, Casscells SW, Litovsky S, Rumberger J, Badimon JJ, Stefanadis C, Moreno P, Pasterkamp G, Fayad Z, Stone PH, Waxman S, Raggi P, Madjid M, Zarrabi A, Burke A, Yuan C, Fitzgerald PJ, Siscovick DS, de Korte CL, Aikawa M, Juhani Airaksinen KE, Assmann G, Becker CR, Chesebro JH, Farb A, Galis ZS, Jackson C, Jang IK, Koenig W, Lodder RA, March K, Demirovic J, Navab M, Priori SG, Rekhter MD, Bahr R, Grundy SM, Mehran R, Colombo A, Boerwinkle E, Ballantyne C, Insull W, Schwartz RS, Vogel R, Serruys PW, Hansson GK, Faxon DP, Kaul S, Drexler H, Greenland P, Muller JE, Virmani R, Ridker PM, Zipes DP, Shah PK, Willerson JT. From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part I. Circulation 2003; 108:1664-72. [PMID: 14530185 DOI: 10.1161/01.cir.0000087480.94275.97] [Citation(s) in RCA: 1770] [Impact Index Per Article: 84.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document focuses on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.
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Affiliation(s)
- Morteza Naghavi
- The Center for Vulnerable Plaque Research, University of Texas-Houston, The Texas Heart Institute, and President Bush Center for Cardiovascular Health, Memorial Hermann Hospital, Houston, USA.
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Faries PL, Agarwal G, Lookstein R, Bernheim JW, Cayne NS, Cadot H, Goldman J, Kent KC, Hollier LH, Marin ML. Use of cine magnetic resonance angiography in quantifying aneurysm pulsatility associated with endoleak. J Vasc Surg 2003; 38:652-6. [PMID: 14560208 DOI: 10.1016/s0741-5214(03)00944-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Persistent aneurysm perfusion or endoleak is associated with pulsatility of abdominal aortic aneurysm (AAA) after endovascular repair. However, the resultant pulsatile change in aneurysm diameter may be difficult to quantify, and therefore its significance is unknown. In this study cine magnetic resonance angiography (MRA) was used to quantify aneurysm wall motion during the cardiac cycle and to correlate it with the presence and type of endoleak. METHODS Cine MRA was performed in 16 patients undergoing endovascular repair of AAA. A 1.5 T magnet and post-processing with GEMS 4.0 Fiesta computerized video image analysis software were used to calculate maximum aortic diameter during systole and diastole. Changes in aortic diameter were determined from these measurements. Cine MRA was performed on aneurysms before treatment and in patients with and without endoleak after endovascular repair. Type of endoleak was confirmed at angiography in all cases. Four patients had antegrade (type I) endoleak, and eight patients had retrograde (type II) endoleak; no endoleak was present in four patients. Endovascular grafts with stent support throughout the entire length of the graft (Talent) were used in all cases (14 bifurcated grafts, 2 tube grafts). RESULTS Cine MRA demonstrated significantly greater wall motion and resultant change in aneurysm diameter in patients with type I endoleak compared with patients without endoleak (type I, 2.14 +/- 1.28 mm vs no endoleak, 0.12 +/- 0.09 mm, P =.001). Change in aneurysm diameter in patients with type II endoleak was not significantly greater than in patients with no endoleak (type II, 0.26 +/- 0.21 mm vs no endoleak, 0.12 +/- 0.09 mm, P = NS). Untreated aneurysms demonstrated the greatest change in diameter during the cardiac cycle (3.51 +/- 0.79 mm). CONCLUSION Cine MRA may be used to accurately quantify AAA wall motion before and after endovascular stent-graft treatment. The extent of change in diameter corresponds to the type of endoleak, with antegrade (type I) endoleak generating greater pulsatile change in diameter than retrograde-collateral (type II) endoleak or no endoleak. Cine MRA may provide a noninvasive means of assessing the success of endovascular treatment of AAA. Further studies will be necessary to confirm the utility and efficacy of cine MRA in postoperative assessment of endovascular aneurysm repair.
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Affiliation(s)
- Peter L Faries
- Division of Vascular Surgery, Department of Surgery, New York-Presbyterian Hospital, Weill Cornell Medical School, 525 E. 68th Street, P705, New York, NY, USA.
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74
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Fayad ZA, Choudhury RP, Fuster V. Magnetic resonance imaging of coronary atherosclerosis. Curr Atheroscler Rep 2003; 5:411-7. [PMID: 12911852 DOI: 10.1007/s11883-003-0013-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Zahi A Fayad
- Imaging Science Laboratories, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1234, New York, NY 10029, USA.
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75
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Abstract
As blood clots it goes through predictable stages that reflect the oxygenation state of hemoglobin within the red cells. One of these stages results in the formation of methemoglobin. This substance acts an endogenous contrast agent when imaged using a T1-weighted magnetic resonance sequence (Magnetic Resonance Direct Thrombus Imaging, MRDTI) - appearing as high signal. MRDTI can therefore be used to detect subacute thrombosis. This technique has been applied in a number of clinical settings arising as a result of thrombosis. Deep vein thrombosis and pulmonary embolism are both readily detected using MRDTI, providing a single imaging modality for the detection of venous thromboembolic disease. The technique is also effective in the peripheral arterial tree. Furthermore, thrombosis within vessel wall atherosclerosis is a marker of vulnerable plaque likely to produce symptoms. The MRDTI technique has thus proved useful in identifying complicated plaque in the carotid arteries in the setting of transient and permanent cerebral ischemia. MRDTI therefore holds promise as a technique that is capable of detecting high risk vessel wall disease prior to significant or permanent end organ damage. Because of the non-invasive nature of magnetic resonance imaging (MRI), application of MRDTI in the research setting for the monitoring of therapeutic interventions in a wide number of settings within vascular disease is very appealing.
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Affiliation(s)
- A R Moody
- Department of Medical Imaging, Sunnybrook and Women's College, Health Sciences Center, Toronto, Canada.
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76
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Murphy RE, Moody AR, Morgan PS, Martel AL, Delay GS, Allder S, MacSweeney ST, Tennant WG, Gladman J, Lowe J, Hunt BJ. Prevalence of complicated carotid atheroma as detected by magnetic resonance direct thrombus imaging in patients with suspected carotid artery stenosis and previous acute cerebral ischemia. Circulation 2003; 107:3053-8. [PMID: 12796136 DOI: 10.1161/01.cir.0000074204.92443.37] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND It is recognized that complicated plaque largely accounts for the morbidity and mortality from atherosclerosis. Ideally, investigation of symptomatic and asymptomatic patients would identify atheromatous plaques independently of stenosis. We have previously shown that a magnetic resonance direct thrombus imaging (MRDTI) technique demonstrates complicated atheroma as high signal within the carotid arterial wall. We used this technique to examine the prevalence of complicated carotid plaque in vivo in the ipsilateral arteries of recently symptomatic patients with suspected carotid artery stenosis and to compare this with their contralateral arteries and with those of healthy age- and sex-matched controls. METHODS AND RESULTS The carotid arteries of 120 patients with suspected severe carotid artery stenosis and previous acute cerebral ischemia were imaged using MRDTI, as were 28 control arteries. High signal was not seen in any control artery. However, there was a 60% prevalence of high signal, suggestive of complicated plaque in the patients' ipsilateral arteries. The prevalence of high signal was significantly greater in the patients' ipsilateral vessels compared with the contralateral, asymptomatic side (60% versus 36%, chi2 P<0.001), particularly for vessels of only moderate stenosis. CONCLUSIONS MRDTI high signal suggestive of complicated plaque is prevalent in the ipsilateral carotid arteries of patients with carotid stenosis and recent cerebral ischemic events. MRDTI has a potential role in identifying "at risk" plaque, studying atherogenesis and the effects of plaque-modifying strategies.
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Affiliation(s)
- Rachael E Murphy
- Department of Academic Radiology, University Hospital, Nottingham, UK.
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77
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Moody AR, Murphy RE, Morgan PS, Martel AL, Delay GS, Allder S, MacSweeney ST, Tennant WG, Gladman J, Lowe J, Hunt BJ. Characterization of complicated carotid plaque with magnetic resonance direct thrombus imaging in patients with cerebral ischemia. Circulation 2003; 107:3047-52. [PMID: 12796133 DOI: 10.1161/01.cir.0000074222.61572.44] [Citation(s) in RCA: 327] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Thromboembolic disease secondary to complicated carotid atherosclerotic plaque is a major cause of cerebral ischemia. Clinical management relies on the detection of significant (>70%) carotid stenosis. A large proportion of patients suffer irreversible cerebral ischemia as a result of lesser degrees of stenosis. Diagnostic techniques that can identify nonstenotic high-risk plaque would therefore be beneficial. High-risk plaque is defined histologically if it contains hemorrhage/thrombus. Magnetic resonance direct thrombus imaging (MRDTI) is capable of detecting methemoglobin within intraplaque hemorrhage. We assessed this as a marker of complicated plaque and compared its accuracy with histological examination of surgical endarterectomy specimens. METHODS AND RESULTS Sixty-three patients underwent successful MRDTI and endarterectomy with histological examination. Of these, 44 were histologically defined as complicated (type VI plaque). MRDTI demonstrated 3 false-positive and 7 false-negative results, giving a sensitivity and specificity of 84%, negative predictive value of 70%, and positive predictive value of 93%. The interobserver (kappa=0.75) and intraobserver (kappa=0.9) agreement for reading MRDTI scans was good. CONCLUSIONS MRDTI of the carotid vessels in patients with cerebral ischemia is an accurate means of identifying histologically confirmed complicated plaque. The high contrast generated by short T1 species within the plaque allows for ease of interpretation, making this technique highly applicable in the research and clinical setting for the investigation of carotid atherosclerotic disease.
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Affiliation(s)
- Alan R Moody
- Department of Academic Radiology, Medical School, University Hospital, Nottingham, UK.
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78
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Wentzel JJ, Aguiar SH, Fayad ZA. Vascular MRI in the diagnosis and therapy of the high risk atherosclerotic plaque. J Interv Cardiol 2003; 16:129-42. [PMID: 12768916 DOI: 10.1046/j.1540-8183.2003.08024.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Disruption of a high risk plaque is known as the primary cause of cardiovascular events. Characterization of arterial wall components has become an essential adjunct in the identification of patients with plaques prone to rupture. Magnetic Resonance Imaging (MRI) has been revealed as one of the noninvasive tools possibly capable of identifying and characterizing high risk atherosclerotic plaque. MRI may facilitate diagnosis, and guide and serially monitor interventional and pharmacological treatment of atherosclerotic disease. In addition, it permits the simultaneous assessment of the anatomy, morphology, and hemodynamics for the study of flow-induced atherogenesis. It possibly will identify asymptomatic patients with subclinical atherosclerosis. This has potential significance for the improvement of strategies in primary and secondary prevention.
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Affiliation(s)
- Jolanda J Wentzel
- Zena and Michael A. Wiener Cardiovascular Institute, Imaging Science Laboratories, Mount Sinai School of Medicine, New York, NY, USA
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79
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Abstract
Despite crucial advances in our knowledge of the pathologic mechanisms and the availability of effective diagnostic and treatment modalities, coronary atherothrombosis remains the most frequent cause of ischemic heart disease. Plaque disruption with superimposed thrombosis is the main cause of unstable angina, myocardial infarction, and sudden death. New findings have recently introduced exciting concepts that could have major impact on the treatment of the atherothrombotic disease. We will discuss the mechanisms that lead to the development of atherothrombosis and those responsible for the acute coronary syndromes, as well as some of the concepts derived from in vivo observations using new imaging technologies (eg, high-resolution magnetic resonance imaging).
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Affiliation(s)
- Roberto Corti
- Zena and Michael Wiener Cardiovascular Institute, Mount Sinai School of Medicine, New York, New York 10029, USA
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80
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Abstract
Imaging methods to quantify the progression and regression of atherosclerosis could play a strong role in the management of patients. High-resolution, noninvasive MR imaging may provide exhaustive 3D anatomical information about the lumen and the vessel wall. Furthermore, MR imaging has the ability to characterize plaque composition and microanatomy and therefore to identify lesions vulnerable to rupture or erosion. The high resolution of MR imaging and the development of sophisticated contrast agents offer the promise of molecular in vivo molecular imaging of the plaque. This may aid early intervention (eg, lipid-lowering drug regiments) in both primary and secondary treatment of vascular disease in all arterial beds.
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Affiliation(s)
- Zahi A Fayad
- Department of Radiology, The Zena and Michael A. Wiener Cardiovascular Institute, Imaging Science Laboratories, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1234, New York, NY 10029, USA.
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81
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Abstract
Atherosclerotic plaque stability depends on 3 factors: (1) lipid core, (2) fibrous cap and its thickness, and (3) inflammation within the cap. Magnetic resonance imaging (MRI) is a noninvasive technique that can provide information on these plaque components using a variety of pulse sequences. Assessment of plaque volume and tissue components and the efficacy of lipid-lowering therapy has been performed in human aorta and carotid arteries. Imaging the coronary wall for plaque burden is a novel application of MRI. Newer approaches also include intravascular and transesophageal MRI techniques. Several emerging MR contrast agents being tested in animal models hold promise for targeted imaging of plaque. MRI is a powerful noninvasive imaging tool with high spatial resolution that continues to prove its value in determining atherosclerotic plaque volume and tissue components.
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Affiliation(s)
- Christopher M Kramer
- Department of Radiology, and Cardiac MRI, University of Virginia Health System, Charlottesville 22908, USA.
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Jaffer FA, Tung CH, Gerszten RE, Weissleder R. In vivo imaging of thrombin activity in experimental thrombi with thrombin-sensitive near-infrared molecular probe. Arterioscler Thromb Vasc Biol 2002; 22:1929-35. [PMID: 12426227 DOI: 10.1161/01.atv.0000033089.56970.2d] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Thrombin, a serine protease, plays an important role in thrombosis as well as other cellular and developmental processes. In this study, we investigated the ability of a novel thrombin-activatable molecular probe to provide in vivo images of thrombin activity in experimental thrombi. METHODS AND RESULTS The thrombin probe consists of a near-infrared (NIR) fluorochrome attached to a delivery vehicle via a thrombin-specific oligopeptide substrate. In human blood, endogenous thrombin activated the thrombin probe and increased the fluorescence signal by 18-fold (P=0.008). Hirudin, a specific thrombin inhibitor, suppressed probe activation by 82% (P=0.007). Imaging of in vivo thrombin activity was then investigated in acute experimental murine thrombosis models up to 12 hours. After systemic thrombin probe injection, focal NIR fluorescence signal enhancement was rapidly detected within acute and subacute thrombi. In contrast, no thrombosis signal enhancement was seen in similar experiments with a control NIR fluorochrome. CONCLUSIONS Thrombin activity can be imaged in vivo by using a novel thrombin-activatable and thrombin-specific NIR molecular probe. The thrombin probe could enhance the understanding of the role of thrombin in thrombogenesis and other homeostatic and pathological conditions.
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Affiliation(s)
- Farouc A Jaffer
- Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129, USA.
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Fuster V, Corti R, Badimon JJ. The Mikamo Lecture 2002. Therapeutic targets for the treatment of atherothrombosis in the new millennium--clinical frontiers in atherosclerosis research. Circ J 2002; 66:783-90. [PMID: 12224812 DOI: 10.1253/circj.66.783] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Valentin Fuster
- The Zena and Michael Wiener Cardiovascular Institute, Mount Sinai School of Medicine, New York, NY 10029, USA.
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85
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Abstract
The assessment of atherothrombotic plaques by imaging techniques is essential for the in vivo identification of vulnerable plaques. Several invasive and noninvasive imaging techniques are available to assess atherothrombotic disease. The use of some of the available imaging modalities for the study of regression and progression of atherothrombosis are described in more detail in the subsequent articles.
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Affiliation(s)
- Zahi A Fayad
- Department of Radiology, Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, Imaging Science Laboratories, Box 1234, New York, NY 10029, USA.
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Fayad ZA. Noncoronary and coronary atherothrombotic plaque imaging and monitoring of therapy by MRI. Neuroimaging Clin N Am 2002; 12:461-71. [PMID: 12486833 DOI: 10.1016/s1052-5149(02)00023-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In the future, the use of imaging methods to quantify the progression and regression of atherosclerosis could play a strong role in the management of patients. High-resolution, noninvasive MRI may provide exhaustive 3-D anatomic information about the lumen and the vessel wall. Furthermore, MRI has the ability to characterize plaque composition and microanatomy and therefore to identify lesions vulnerable to rupture or erosion. The high resolution of MRI and the development of sophisticated contrast agents offer the promise of molecular in vivo molecular imaging of the plaque. This may aid early intervention (e.g., lipid lowering drug regiments) in both primary and secondary treatment of vascular disease in all arterial beds.
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Affiliation(s)
- Zahi A Fayad
- Department of Radiology, Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, Imaging Science Laboratories, Box 1234, New York, NY 10029, USA.
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87
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Abstract
MRI is a powerful noninvasive imaging tool with high spatial resolution that continues to prove its value in determining atherosclerotic plaque size, volume, and tissue components. Multispectral MRI sequences have been validated to characterize atherosclerotic plaque components in animals; they have recently been applied to human aorta and carotid artery and are being used to identify the vulnerable plaque. The ability to measure wall thickness in human coronary artery wall has been realized. Future developments may allow plaque characterization in the coronary arteries with surface coil imaging, but intravascular MRI may play an important role in this regard. Novel contrast agents for identifying inflammation and thrombus within atherosclerotic plaque will aid in the identification of higher-risk atherosclerotic disease. Lastly, MRI has progressed to the point where it can be used in serial studies of atherosclerotic plaque progression and regression in the face of therapeutic intervention. MRI will continue to evolve an important role in imaging of atherosclerotic plaque.
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Affiliation(s)
- C Joon Choi
- Department of Internal Medicine, University of Virginia Health System, Charlottesville 22908, USA
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88
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Choudhury RP, Fuster V, Badimon JJ, Fisher EA, Fayad ZA. MRI and characterization of atherosclerotic plaque: emerging applications and molecular imaging. Arterioscler Thromb Vasc Biol 2002; 22:1065-74. [PMID: 12117718 DOI: 10.1161/01.atv.0000019735.54479.2f] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Noninvasive high-resolution magnetic resonance has the potential to image atherosclerotic plaque and to determine its composition and microanatomy. This review summarizes the rationale for plaque imaging and describes the characteristics of plaque by use of existing MRI techniques. The use of MRI in human disease and in animal models, particularly in rabbits and mice, is presented. Present and future applications of MRI, including real-time vascular intervention, new contrast agents, and molecular imaging, are also discussed.
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Affiliation(s)
- Robin P Choudhury
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
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