Assessment Of Atherosclerotic Plaque Burden Research Articles

Feasibility of Coronary Computed Tomography Angiography Assessment of Explanted Donor Hearts

In the United Kingdom, coronary angiography is rarely performed of donation after brain death donors. Currently up to 30% of potential donor hearts are not utilised due to potential but unconfirmed coronary disease. For Donation After Circulatory death donors, coronary angiography is prohibited, as are all antemortem interventions. We believe that ex situ coronary CT angiography (CTA) will be logistically more feasible than in situ donor coronary angiography or ex situ coronary angiography allowing greater yield of donor hearts. Organ retrieval is performed by direct procurement and perfusion. The aorta of the donor heart is cannulated to allow retrograde perfusion of the heart via the coronary arteries in the setting of a competent aortic valve. Electrocardiographic (ECG) monitoring is performed. The donor heart is paced epicardially to a rate between 70-90 beats per minute as required. Coronary CTA is performed after direct administration of contrast media (iomeron 350) and nitroglycerin administration. Coronary CTA post processing facilitated segmental analysis of all of the coronary arteries with detailed assessment of atherosclerotic plaque burden, plaque morphology and luminal stenosis. Coronary CTA findings are directly compared to histological correlation of plaque burden. Two human cardiac allografts (donation after brain death) were assessed using coronary CTA during ex-vivo perfusion on a local centre ex-vivo perfusion device. Images were reconstructed using Siemens SyngoVia software. In both patients eccentric atherosclerotic plaque burden was quantified using conventional techniques and luminal calibre assessed. Assessment of ex-vivo coronary arteries is feasible using coronary CTA during ex-vivo perfusion of donor hearts. Atherosclerotic plaque and luminal stenosis of ex-vivo coronary arteries can be diagnosed using coronary CTA.

Comprehensive and Rapid Assessment of Carotid Plaques in Acute Stroke Using a New Single Sweep Method for Three‐Dimensional Carotid Ultrasound

We describe a 68-year-old man with acute stroke in whom the newly developed single sweep method for three-dimensional (3D) carotid ultrasound provided a rapid and comprehensive assessment of atherosclerotic plaque burden in the internal carotid artery. The two-dimensional duplex carotid scan diagnosed 50-69% stenosis, and with the three-dimensional method, the markedly hypoechogenic plaque (total volume 1.42 mL) was shown to occupy 77% of the total arterial volume (1.84 mL), consistent with severe lesion. The ultrasound findings were confirmed by computed tomographic angiography and subsequent carotid endarterectomy. The new single sweep 3D carotid ultrasound has the potential to become a valuable clinical tool in the assessment of stroke patients.

Beyond Coronary Stenosis: Coronary Computed Tomographic Angiography for the Assessment of Atherosclerotic Plaque Burden

Coronary computed tomographic angiography (CCTA) is emerging as a key non-invasive method for assessing cardiovascular risk by measurement of coronary stenosis and coronary artery calcium (CAC). New advancements in CCTA technology have led to the ability to directly identify and quantify the so-called "vulnerable" plaques that have features of positive remodeling and low density components. In addition, CCTA presents a new opportunity for noninvasive measurement of total coronary plaque burden that has not previously been available. The use of CCTA needs also to be balanced by its risks and, in particular, the associated radiation exposure. We review current uses of CCTA, CCTA's ability to measure plaque quantity and characteristics, and new developments in risk stratification and CCTA technology. CCTA represents a quickly developing field that will play a growing role in the non-invasive management of cardiovascular disease.

Assessment of atherosclerotic plaque burden with an elastin-specific magnetic resonance contrast agent

Atherosclerosis and its consequences remain the main cause of mortality in industrialized and developing nations. Plaque burden and progression have been shown to be independent predictors for future cardiac events by intravascular ultrasound. Routine prospective imaging is hampered by the invasive nature of intravascular ultrasound. A noninvasive technique would therefore be more suitable for screening of atherosclerosis in large populations. Here we introduce an elastin-specific magnetic resonance contrast agent (ESMA) for noninvasive quantification of plaque burden in a mouse model of atherosclerosis. The strong signal provided by ESMA allows for imaging with high spatial resolution, resulting in accurate assessment of plaque burden. Additionally, plaque characterization by quantifying intraplaque elastin content using signal intensity measurements is possible. Changes in elastin content and the high abundance of elastin during plaque development, in combination with the imaging properties of ESMA, provide potential for noninvasive assessment of plaque burden by molecular magnetic resonance imaging (MRI).

Three-Dimensional T2-Weighted MRI of the Human Femoral Arterial Vessel Wall at 3.0 Tesla

To evaluate the potential use of a novel 3D turbo spin-echo (TSE) T2-weighted (T2w) technique for assessing the vessel wall in the superficial femoral artery at 3.0 T. Magnetic resonance imaging can be used for the noninvasive assessment of atherosclerotic plaque burden in the peripheral circulation. Although black-blood 2D TSE techniques have been used for femoral arterial wall imaging, these techniques require prolonged imaging time to cover a large field of view required to cover the leg. Recently, variable-flip-angle 3D TSE T2w (SPACE) has been introduced as a fast vessel wall imaging technique with submillimeter spatial resolution. A systematic investigation of the application of this technique to femoral arterial wall imaging has yet to be performed. Fifteen healthy volunteers and 3 patients with peripheral arterial disease (PAD) underwent 3D SPACE imaging of the superficial femoral artery at 3.0 T, with the conventional 2D TSE T2w imaging as a reference. Muscle-lumen contrast to noise ratio (CNR) and wall/lumen volumes (WV, LV) were measured at the matched locations on the 3D and 2D image sets. Statistical comparison on a per-subject basis was conducted to determine the difference and agreement between 3D SPACE and the 2D TSE techniques. The 3D SPACE data sets enabled vessel visualization from arbitrary orientation through multiplanar reformation technique. Muscle-lumen CNR was significantly higher with 3D SPACE than with the 2D TSE (3.12 +/- 0.84 vs. 2.17 +/- 0.34, P < 0.01). This trend was confirmed when CNR efficiency (CNR(eff)) values were further compared. A similar trend was observed in PAD patients (SPACE vs. 2D TSE T2w: CNR 2.35 +/- 0.13 vs. 1.77 +/- 0.25; CNR(eff) 15.35 +/- 0.61 vs. 3.59 +/- 2.62. all P < 0.05). Measurements of WV and LV from the 3D and 2D techniques were highly correlated in volunteers and PAD patients (volunteers, WV: linear regression r2 = 0.98, LV: r2 = 0.98, P < 0.001 for both; patients, WV: linear regression r2 = 0.96, LV: r2 = 0.94, P < 0.001 for both). We established the feasibility of using the 3D SPACE technique for vessel wall imaging in the superficial femoral artery at 3.0T. High, isotropic-resolution SPACE images, with the aid of multiplanar reformation, enable superior vessel wall visualization. Superior blood signal suppression comparable to vessel wall morphologic measurements, and superior time efficiency compared to conventional 2D TSE imaging indicate the great potential of the SPACE method as a noninvasive imaging technique for the assessment of atherosclerotic plaque burden in PAD patients.

Non‐invasive MRI of mouse models of atherosclerosis

Early detection and characterization of atherosclerotic lesions susceptible to sudden rupture and thrombosis may decrease morbidity and mortality. Plaque development has been extensively studied using MRI in animal models of rapidly progressing atherosclerosis. These transgenic mice develop atherosclerotic plaques in the aortic root by 10 weeks of age and throughout the vasculature thereafter. Transplantation of lesion-containing segments of the thoracic aorta into wild-type mice results in nearly total reversal of atherosclerosis, making it possible to study both progression and regression of plaques in this model. MRI permits the non-invasive accurate assessment of atherosclerotic plaque burden and the differentiation between the lipid and fibrous content of individual plaques, thus providing a non-invasive approach to serially monitor the evolution of individual plaques in the mouse models. Emergence of novel contrast agents that target a diverse set of molecules within the plaque are now helping to elucidate the changes at the cellular and molecular levels during plaque progression and regression.