Determination of edema in porcine coronary arteries by T2 weighted cardiovascular magnetic resonance

Detection of Vulnerable Coronary Plaques Using Invasive and Non-Invasive Imaging Modalities

Acute coronary syndrome (ACS) mostly arises from so-called vulnerable coronary plaques, particularly prone for rupture. Vulnerable plaques comprise a specific type of plaque, called the thin-cap fibroatheroma (TFCA). A TCFA is characterized by a large lipid-rich necrotic core, a thin fibrous cap, inflammation, neovascularization, intraplaque hemorrhage, microcalcifications or spotty calcifications, and positive remodeling. Vulnerable plaques are often not visible during coronary angiography. However, different plaque features can be visualized with the use of intracoronary imaging techniques, such as intravascular ultrasound (IVUS), potentially with the addition of near-infrared spectroscopy (NIRS), or optical coherence tomography (OCT). Non-invasive imaging techniques, such as computed tomography coronary angiography (CTCA), cardiovascular magnetic resonance (CMR) imaging, and nuclear imaging, can be used as an alternative for these invasive imaging techniques. These invasive and non-invasive imaging modalities can be implemented for screening to guide primary or secondary prevention therapies, leading to a more patient-tailored diagnostic and treatment strategy. Systemic pharmaceutical treatment with lipid-lowering or anti-inflammatory medication leads to plaque stabilization and reduction of cardiovascular events. Additionally, ongoing studies are investigating whether modification of vulnerable plaque features with local invasive treatment options leads to plaque stabilization and subsequent cardiovascular risk reduction.

Systemic involvement in ACS: Using CMR imaging to compare the aortic wall in patients with and without acute coronary syndrome

Background/Objectives

Previous studies have demonstrated that in acute coronary syndrome (ACS), plaque destabilization and vessel inflammation, represented by vessel edema, often occur simultaneously in multiple coronaries, as well as extend to the cerebrovascular system. Our aim was to determine whether the inflammatory vascular processes occurring within the coronaries during ACS extend simultaneously to the descending aorta.

Methods

We prospectively enrolled 111 patients (56 ACS patients and 55 non-ACS patients with known coronary artery disease) to undergo cardiac magnetic resonance of the thoracic aortic wall at presentation and at three-month follow-up. The primary outcome was change in aortic wall area (AWA) and maximal aortic wall thickness (AWT) from baseline to three-month follow-up. Secondary outcomes were baseline and follow-up differences in AWA and AWT, and changes in C-reactive protein (CRP).

Results

There was a significant reduction in mean AWA (p = 0.01) and AWT (p = 0.01) between index and follow up scans in ACS group, with no significant changes in non ACS group (both p>0.1) and no difference between ACS and non-ACS groups (p = 0.22). There was no significant difference in AWA and AWT at baseline (p>0.36) and follow-up (p>0.2) between groups. There was a significant reduction in CRP in both groups (p<0.01), with higher reduction in ACS patients (p<0.01)

Conclusions

There was a reduction in aortic wall size, aortic wall area, and aortic wall thickness in patients presenting with ACS, and no change in non-ACS patients. There were no interval between-group differences in these measurements. We observed a reduction in C-reactive protein in both groups, with higher reduction noted in ACS patients.

Proximal internal carotid artery stenosis associates with diffuse wall thickening in petrous arterial segment of moyamoya disease patients: a three-dimensional magnetic resonance vessel wall imaging study

PURPOSE

To investigate the association between proximal internal carotid artery (ICA) luminal narrowing and diffuse wall thickening (DWT) in ipsilateral petrous ICA in moyamoya disease (MMD) patients.

METHODS

Forty-one MMD (mean age 42.8 ± 11.0 years, 19 males) and 36 atherosclerotic patients (mean age 61.5 ± 7.1 years, 31 males) and 41 healthy controls were recruited and underwent carotid MR vessel wall imaging. The luminal narrowing of proximal ICA was evaluated by the diameter ratio of ICA to common carotid artery (DR_ICA/CCA). The wall thickness of petrous ICA was measured on T1-VISTA images. The enhancement degree of petrous ICA was recorded and graded into four grades (none to marked) on the CE-T1-VISTA images. The correlation between wall thickness in petrous ICA and DR_ICA/CCA was analyzed_. RESULTS: In total, 81 arteries of MMD patients and 64 arteries of atherosclerotic patients were included for analysis. The DR_ICA/CCA was significantly correlated with the wall thickness in petrous ICA in MMD (r = - 0.434, P < 0.001) and atherosclerotic groups (r = - 0.604, P < 0.001). Logistic regression analysis revealed that odds ratio (OR) of DR_ICA/CCA was 4.433 (95% CI 1.980-9.925, P < 0.001) and 2.212 (95% CI 1.253-3.905, P = 0.006) in MMD and atherosclerotic groups in discriminating petrous ICA DWT after adjusting for confounding factors. An increasing trend was found in prevalence of DWT and wall thickness with enhancement grades in petrous ICA in MMD (P = 0.02 and P = 0.01) and atherosclerotic groups (P < 0.001 and P < 0.001), respectively.

CONCLUSIONS

The proximal ICA luminal narrowing is significantly associated with wall thickness and diffuse wall thickening in ipsilateral petrous ICA in patients with carotid steno-occlusive diseases regardless of MMD or atherosclerosis.

Early Detection and Treatment of the Vulnerable Coronary Plaque

Early identification and treatment of the vulnerable plaque, that is, a coronary artery lesion with a high likelihood of rupture leading to an acute coronary syndrome, have gained great interest in the cardiovascular research field. Postmortem studies have identified clear morphological characteristics associated with plaque rupture. Recent advances in invasive and noninvasive coronary imaging techniques have empowered the clinician to identify suspected vulnerable plaques in vivo and paved the way for the evaluation of therapeutic agents targeted at reducing plaque vulnerability. Local treatment of vulnerable plaques by percutaneous coronary intervention and systemic treatment with anti-inflammatory and low-density lipoprotein–lowering drugs are currently being investigated in large randomized clinical trials to assess their therapeutic potential for reducing adverse coronary events. Results from these studies may enable a more patient-tailored strategy for the treatment of coronary artery disease.

Association between proximal internal carotid artery steno-occlusive disease and diffuse wall thickening in its petrous segment: a magnetic resonance vessel wall imaging study

PURPOSE

Significant stenosis or occlusion in carotid arteries may lead to diffuse wall thickening (DWT) in the arterial wall of downstream. This study aimed to investigate the correlation between proximal internal carotid artery (ICA) steno-occlusive disease and DWT in ipsilateral petrous ICA.

METHODS

Symptomatic patients with atherosclerotic stenosis (>0%) in proximal ICA were recruited and underwent carotid MR vessel wall imaging. The 3D motion sensitized-driven equilibrium prepared rapid gradient-echo (3D-MERGE) was acquired for characterizing the wall thickness and longitudinal extent of the lesions in petrous ICA and the distance from proximal lesion to the petrous ICA. The stenosis degree in proximal ICA was measured on the time-of-flight (TOF) images.

RESULTS

In total, 166 carotid arteries from 125 patients (mean age 61.0 ± 10.5 years, 99 males) were eligible for final analysis and 64 showed DWT in petrous ICAs. The prevalence of severe DWT in petrous ICA was 1.4%, 5.3%, 5.9%, and 80.4% in ipsilateral proximal ICAs with stenosis category of 1%-49%, 50%-69%, 70%-99%, and total occlusion, respectively. Proximal ICA stenosis was significantly correlated with the wall thickness in petrous ICA (r = 0.767, P < 0.001). Logistic regression analysis showed that proximal ICA stenosis was independently associated with DWT in ipsilateral petrous ICA (odds ratio (OR) = 2.459, 95% confidence interval (CI) 1.896-3.189, P < 0.001].

CONCLUSION

Proximal ICA steno-occlusive disease is independently associated with DWT in ipsilateral petrous ICA.

Noninvasive diagnosis of vulnerable coronary plaque

Myocardial infarction and sudden cardiac death are frequently the first manifestation of coronary artery disease. For this reason, screening of asymptomatic coronary atherosclerosis has become an attractive field of research in cardiovascular medicine. Necropsy studies have described histopathological changes associated with the development of acute coronary events. In this regard, thin-cap fibroatheroma has been identified as the main vulnerable coronary plaque feature. Hence, many imaging techniques, such as coronary computed tomography, cardiac magnetic resonance or positron emission tomography, have tried to detect noninvasively these histomorphological characteristics with different approaches. In this article, we review the role of these diagnostic tools in the detection of vulnerable coronary plaque with particular interest in their advantages and limitations as well as the clinical implications of the derived findings.

Atherosclerosis: a chronic inflammatory disease mediated by mast cells

Inflammation is a process that plays an important role in the initiation and progression of atherosclerosis and immune disease, involving multiple cell types, including macrophages, T-lymphocytes, endothelial cells, smooth muscle cells and mast cells. The fundamental damage of atherosclerosis is the atheromatous or fibro-fatty plaque which is a lesion that causes several diseases. In atherosclerosis the innate immune response, which involves macrophages, is initiated by the arterial endothelial cells which respond to modified lipoproteins and lead to Th1 cell subset activation and generation of inflammatory cytokines and chemoattractant chemokines. Other immune cells, such as CD4+ T inflammatory cells, which play a critical role in the development and progression of atherosclerosis, and regulatory T cells [Treg], which have a protective effect on the development of atherosclerosis are involved. Considerable evidence indicates that mast cells and their products play a key role in inflammation and atherosclerosis. Activated mast cells can have detrimental effects, provoking matrix degradation, apoptosis, and enhancement as well as recruitment of inflammatory cells, which actively contributes to atherosclerosis and plaque formation. Here we discuss the relationship between atherosclerosis, inflammation and mast cells.

Coronary artery wall imaging

Like X-Ray contrast angiography, MR coronary angiograms show the vessel lumens rather than the vessels themselves. Consequently, outward remodeling of the vessel wall, which occurs in subclinical coronary disease before luminal narrowing, cannot be seen. The current gold standard for assessing the coronary vessel wall is intravascular ultrasound, and more recently, optical coherence tomography, both of which are invasive and use ionizing radiation. A noninvasive, low-risk technique for assessing the vessel wall would be beneficial to cardiologists interested in the early detection of preclinical disease and for the safe monitoring of the progression or regression of disease in longitudinal studies. In this review article, the current state of the art in MR coronary vessel wall imaging is discussed, together with validation studies and recent developments.

Imaging of carotid artery vessel wall edema using T2-weighted cardiovascular magnetic resonance

BACKGROUND

Atherothrombosis remains a major health problem in the western world, and carotid atherosclerosis is an important contributor to embolic ischemic strokes. It remains a clinical challenge to identify rupture-prone atherosclerotic plaques before clinical events occur. Inflammation, endothelial injury and angiogenesis are features of vulnerable plaques and may all be associated with plaque edema. Therefore, vessel wall edema, which can be detected by 2D T2-weighted cardiovascular magnetic resonance (CMR), may be used as a dynamic marker of disease activity in the atherosclerotic plaque. However, 2D imaging is limited by low spatial resolution in the slice-select direction compared to 3D imaging techniques. We sought to investigate the ability of novel 3D techniques to detect edema induced in porcine carotid arteries by acute balloon injury compared to conventional 2D T2-weighted black-blood CMR.

METHODS

Edema was induced unilaterally by balloon overstretch injury in the carotid artery of nine pigs. Between one to seven hours (average four hours) post injury, CMR was performed using 2D T2-weighted short-tau inversion recovery (T2-STIR), 3D volumetric isotropic turbo spin echo acquisition (VISTA) and 3D T2 prepared gradient-echo (T2prep-GE). The CMR images were compared in terms of signal-to-noise ratio (SNR) and contrast-to-noise (CNR) ratio. Furthermore, the presence of vessel wall injury was validated macroscopically by means of Evans Blue dye that only enters the injured vessel wall.

RESULTS

All three imaging sequences classified the carotid arteries correctly compared to Evans Blue and all sequences demonstrated a significant increase in SNR of the injured compared to the non-injured carotid vessel wall (T2-STIR, p = 0.002; VISTA, p = 0.004; and T2prep-GE, p = 0.003). There was no significant difference between sequences regarding SNR and CNR.

CONCLUSION

The novel 3D imaging sequences VISTA and T2prep-GE perform comparably to conventional 2D T2-STIR in terms of detecting vessel wall edema. The improved spatial coverage of these 3D sequences may facilitate visualization of vessel wall edema to enable detection and monitoring of vulnerable carotid atherosclerotic plaques.

Review of Journal of Cardiovascular Magnetic Resonance 2012

There were 90 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2012, which is an 8% increase in the number of articles since 2011. The quality of the submissions continues to increase. The editors are delighted to report that the 2011 JCMR Impact Factor (which is published in June 2012) has risen to 4.44, up from 3.72 for 2010 (as published in June 2011), a 20% increase. The 2011 impact factor means that the JCMR papers that were published in 2009 and 2010 were cited on average 4.44 times in 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, the progress of the journal's impact over the last 5 years has been impressive. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors have felt that it is useful once per calendar year to summarize the papers for the readership into broad areas of interest or theme, so that areas of interest can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

The emerging role of cardiovascular magnetic resonance in the evaluation of Kawasaki disease

Kawasaki disease (KD) is a vasculitis affecting the coronary and systemic arteries. Myocardial inflammation is also a common finding in KD post-mortem evaluation during the acute phase of the disease. Coronary artery aneurysms (CAAs) develop in 15-25% of untreated children. Although 50-70% of CAAs resolve spontaneously 1-2 years after the onset of KD, the remaining unresolved CAAs can develop stenotic lesions at either their proximal or distal end and can develop thrombus formation leading to ischemia and/or infarction. Cardiovascular magnetic resonance (CMR) has the ability to perform non-invasive and radiation-free evaluation of the coronary artery lumen. Recently tissue characterization of the coronary vessel wall was provided by CMR. It can also image myocardial inflammation, ischemia and fibrosis. Therefore CMR offers important clinical information during the acute and chronic phase of KD. In the acute phase, it can identify myocardial inflammation, microvascular disease, myocardial infarction, deterioration of left ventricular function, changes of the coronary artery lumen and changes of the coronary artery vessel wall. During the chronic phase, CMR imaging might be of value for risk stratification and to guide treatment.

Review of Journal of Cardiovascular Magnetic Resonance 2011

There were 83 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2011, which is an 11% increase in the number of articles since 2010. The quality of the submissions continues to increase. The editors had been delighted with the 2010 JCMR Impact Factor of 4.33, although this fell modestly to 3.72 for 2011. The impact factor undergoes natural variation according to citation rates of papers in the 2 years following publication, and is significantly influenced by highly cited papers such as official reports. However, we remain very pleased with the progress of the journal's impact over the last 5 years. Our acceptance rate is approximately 25%, and has been falling as the number of articles being submitted has been increasing. In accordance with Open-Access publishing, the JCMR articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. For this reason, the Editors feel it is useful to summarize the papers for the readership into broad areas of interest or theme, which we feel would be useful, so that areas of interest from the previous year can be reviewed in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought in the journal. We hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

Determination of acute vascular injury and edema in porcine carotid arteries by T2 weighted cardiovascular magnetic resonance

Inflammation plays an essential role for destabilization and rupture of carotid atherosclerotic plaques causing embolic ischemic stroke. Inflammation of the vessel wall may result in the formation of edema. This study investigated whether edema in the carotid artery wall induced by acute balloon injury could be detected by cardiovascular magnetic resonance (CMR) using a T2-weighted short-tau inversion recovery sequence (T2-STIR). Edema was induced unilaterally by balloon injury in the carotid artery of six pigs. Four to nine days (average six) post injury, the carotid arteries were assessed by T2-STIR and multi-contrast weighted sequences. CMR images were matched to histopathology, validated against Evans blue, and correlated with the amount of fibrinogen in the arterial wall used as an edema marker. T2-STIR images showed that the carotid signal intensity (SI) divided by the sternocleid muscle SI of the injured carotid artery was on average 223% (P = 0.03) higher than that of the uninjured carotid artery. Using a threshold value of 4SD, T2-STIR detected edema in the vessel wall (i.e., hyperintense signal intensity) with a sensitivity of 100% and a specificity of 75%. Agreement was observed between carotid artery wall hyperintense signal intensity and Evans blue uptake (X(2) = 17.1, P < 0.001). The relative signal intensity correlated in a linear fashion with the amount of fibrinogen detected by histopathology (ρ = 0.9, P < 0.001). None of the multi-contrast weighted sequences detected edema in the carotid artery with reasonable sensitivity or specificity. T2-STIR CMR allowed carotid artery wall edema detection and may therefore be a useful non-invasive diagnostic tool for determination of inflammatory activity in the carotid artery wall.