Medical Imaging

PERIOPERATIVE myocardial complications after noncardiac surgery affect more than 1 million operations each year and are leading causes of morbidity and mortality, especially among patients undergoing vascular surgery. Myocardial complications such as perioperative myocardial infarction (MI) are common and are the most likely cause for perioperative death in all surgical populations.1In general surgery, the risk for perioperative MI is 0.8% in men older than 50 yr2and varies with the cardiovascular status, comorbidities, and the extent of the procedure, reaching more than 20% among patients undergoing vascular surgery.3As patients become older and sicker and procedures become more aggressive and extensive, physicians must find novel approaches to evaluate and prepare cardiac patients for noncardiac procedures and reduce perioperative myocardial events.The American Heart Association–American College of Cardiology guidelines for cardiac risk evaluation use the patient's history, physical examination, and functional capacity, and taking into account the expected surgery, one may recommend further assessment with noninvasive testing or coronary angiography.4The purpose of this review is to provide an overview of available imaging tools that could potentially be used for perioperative evaluation of cardiac patients before noncardiac surgery, in accord with recent guidelines and with focus on the recent progress made with cardiac computed tomography (CT).Traditionally, preoperative evaluation has relied on the patient's history, physical examination, and functional capacity. After preoperative evaluation, the physician should determine the clinical predictors as major, intermediate, or minor4and evaluate the functional capacity of the patient. New York Heart Association class II heart failure, which equals 4 metabolic equivalents,4has also been found to be an important predictor of perioperative cardiac complications after major noncardiac surgery. The cutoff value of 4 or more metabolic equivalents determines an adequate cardiac functional capacity and reserve and predicts perioperative cardiac events in patients treated with high-risk noncardiac surgery.5Finally, the extent and risk associated with the procedure should be categorized as major, intermediate, or minor. The cardiac risk is the combined incidence of cardiac death and nonfatal MI and is greater than 5% for high-risk procedures, whereas intermediate-risk procedures have less than 5% cardiac risk (1–5%), and low-risk procedures have less than 1% cardiac risk.4Indeed, based on these criteria, the flowchart of Eagle et al. 4suggests when a noninvasive test or coronary angiography may be appropriate to evaluate cardiac function, reserve, or ability to withstand surgical stress. Pertinent to the utility of evaluating cardiac structure and function, new imaging techniques for evaluation of the heart have emerged in the past couple of decades. These techniques may provide more comprehensive information regarding the structure and function of the heart and coronary arteries, and evaluate adequately patients who have mechanical restrictions to perform exercise-induced stress. Such developments in cardiac imaging may eventually provide an opportunity to revise and refine the steps involving the evaluation of cardiac patients.6,7This approach should be evaluated cautiously and should take into consideration recent recommendations and guidelines. For example, the current American Heart Association–American College of Cardiology guidelines recommend the use of perioperative β-blocker therapy as an alternative approach to decrease cardiovascular risk.8β-Blockers initiated at least 1 week before major vascular surgery and continued for 30 days postoperatively reduced significantly the perioperative incidence of nonfatal MI and death from cardiac causes in high-risk patients.9In addition to beta blockers, statins may reduce perioperative mortality in patients undergoing major vascular surgery and may have an additive effect to β-blockers.10,11The strategy of preoperative coronary artery revascularization before elective major vascular surgery to reduce perioperative cardiac morbidity and mortality was investigated in the Coronary Artery Revascularization Prophylaxis trial, a multicenter study involving patients with vascular disease and significant coronary artery disease (CAD), but no unstable angina. Cardiac revascularization did not result in increased survival, either perioperatively or in long-term follow-up, in patients who needed elective vascular surgery.12However, although the Coronary Artery Revascularization Prophylaxis study is a cornerstone trial in the perioperative care of cardiac patients for noncardiac surgery, it had some limitations. In particular, only 9% of the patients scheduled to undergo vascular operations were eligible for the study. The main reasons for exclusion were insufficient cardiac risk, an urgent vascular surgery, previous revascularization without ischemia, severe coexisting illnesses, left main coronary artery stenosis of at least 50%, left ventricular ejection fraction less than 20%, and severe aortic stenosis. The outcome of these patients has not been adequately evaluated.Indeed, taking into consideration the patient's perioperative cardiac risk according to clinical predictors, functional capacity, and the extent of the future surgery, the anesthesiologist must decide whether further cardiac assessment or perioperative medical management are indicated. Patients whose functional capacity is difficult to establish, who underwent previous coronary revascularization, who have unstable or changed cardiac status, or who have severe comorbidities may need further evaluation. Several imaging techniques are available for evaluation of cardiac patients, including cardiac CT, coronary angiography, stress echocardiography, cardiac magnetic resonance imaging (CMRI), and myocardial nuclear studies.Computed tomography is widely available in large medical centers and is routinely used in clinical practice. The basic principle of CT is that a fan-shaped, thin x-ray beam passes through the body at many angles to allow for cross-sectional images. After collimation of the beam (i.e. , achieving a definitive slice thickness using a collimator) to reduce scatter, the photons are recorded on a corresponding detector array, and the transmission data are digitized. A “filtered back projection” reconstruction algorithm, which takes into account the attenuation of the x-ray beam along its path, allows for reconstruction of the grayscale values of each picture element (pixel) with reference to the value for water and air, to depict cross-sectional images. Reconstruction algorithms and multirow detectors applied in current scanners enable three-dimensional volumetric imaging and multiple high-quality reconstructions of various volumes of interest.13Current clinical scanners used for cardiovascular imaging employ either a rotating x-ray source with a circular, stationary detector array (e.g. , helical CT) or electromagnetic deflection of an electron beam to replace mechanical motion (electron beam computed tomography [EBCT]).14Multidetector computed tomography (MDCT) is a helical CT with a large array of detectors, which allow it to acquire a large number of slices simultaneously (4–256) and greatly increase its resolution. However, to obtain quantitative measurements of tissue opacity within a specific cardiac phase (e.g. , for measurement of perfusion), the scanning time should generally be less than 100 ms.15Sufficiently high temporal resolution (the time required to acquire the data for one image) is currently offered only by the EBCT (50 ms/image) and the novel Dual-Source CT (SOMATOM® Defi-nition; Siemens Medical Systems, Forchheim, Germany) (83 ms/image), a recently released model of MDCT that has two x-ray tubes (rather than one) positioned at 90° to each other, thereby doubling temporal resolution.16However, this technique remains to be validated for such measurements.Electron beam computed tomography was developed in the 1980s and hailed as an ultimate cardiac scanner. It allows almost simultaneous data acquisition from up to eight parallel slices (7–8 mm thick) by rapid sweeping of an electron beam along target rings in as little as 50 ms per scan. Because it does not involve moving parts (and therefore decreases the need for cooling), the speed of acquisition (temporal resolution) with EBCT is faster than with MDCT (table 1) and usually does not require slowing the heart rate pharmacologically. The high speed of EBCT is offset by moderate image quality and relatively restricted power for acquisition of a large number of images, which decreased its popularity for comprehensive cardiac studies. Consequently, its availability is limited, resulting in declining use of this technology.Multidetector computed tomography is a relatively ubiquitous and newer scanner that has temporal resolution of 330–400 ms/image, which enables many studies of cardiac anatomy and global function (e.g. , ejection fraction and cardiac output). Spatial resolution can be achieved with 64-slice scanners using isotropic voxels (consistent three-dimensional image quality in any reconstruction plane) of 0.4 × 0.4 × 0.4 mm. The technique involves continuous rotation of the x-ray tube and detectors and simultaneous translation of the patient through the gantry opening, and can acquire multiple simultaneous sections of variable widths using prospective electrocardiographic triggering.17Alternatively, retrospective electrocardiographic gating enables reconstruction of images at any desired time in the cardiac cycle. Data can be used from multiple slices to reconstruct other imaging planes. The images are of best quality when the resting heart rate (HR) is less than 70 beats/min. At faster heart rates, motion artifacts may become more prominent, and therefore HR may need to be pharmacologically decreased before scanning. The temporal resolution of MDCT determines the overall scan time. As gantry rotation speeds increase, the minimum slice thickness decreases, with submillimeter sections throughout the heart acquired during a single breath hold. The overall CT scan time is approximately 12 s, and the mean total time for the examination is less than 13 min with 64-slice technology.The improvement in MDCT technology enabled the assessment of significant luminal stenosis and identification of nonstenotic atherosclerotic plaques. Virtual noninvasive angiography, with three-dimensional reconstruction of coronary anatomy from cardiac CT images, can provide information about coronary luminal obstruction, calcium scoring, and composition of the plaque.18Furthermore, it has the added benefit of offering fine details of the examined vessels (fig. 1).Excellent sensitivity and specificity were found for evaluation of proximal, middle and distal left anterior descending, first diagonal, proximal and distal circumflex, obtuse marginal and proximal mid and distal right coronary artery.19A meta-analysis of diagnostic performance of MDCT compared with invasive coronary angiography showed a sensitivity of 85% and a specificity of 95% for identification of CAD. On average, 87% of segments had diagnostic image quality, with a significant increase from 78% with 4-slice systems to 96% with the more recent 16-slice systems.6Multidetector computed tomography could provide a clinically useful tool in the workup of symptomatic patients before angiography.20A patient with chronic chest pain indicative of CAD could undergo CT angiography, and if low calcium score and no circumferential calcifications (or other test results indicative of ischemia) are found, invasive angiography may not be indicated, because MDCT has excellent negative predictive value to rule out CAD. By this approach, patients with primarily microvessel disease (which may cause angina and abnormal stress test results) may be identified and not required to go through unnecessary fluoroscopic angiography, and aggressive medical therapy would be indicated before surgery.20MDCT also has high diagnostic accuracy in detecting bypass graft stenosis and occlusions in symptomatic patients after coronary artery bypass grafting, which might potentially reduce dramatically the number of unnecessary invasive angiographies performed in these patients.21However, although the MDCT technique has been extensively evaluated for its accuracy for detection of CAD compared with standard coronary angiography,6,19,20,22it has not been applied for the routine evaluation of cardiac patients for noncardiac surgery and, to date, is not a recommended technique for perioperative risk stratification.The main technical limitations of cardiac CT for evaluation of the coronary arteries include the difficulty in handling cardiac motion, arrhythmia, severe calcifications, vessel size less than 1.5 mm, breathing, the presence of stents, and poor enhancement.22Lesions with extensive calcified components and implanted coronary stents compromise the accuracy of MDCT coronary angiography by causing artifacts.23Stent type and diameter influence evaluability of in-stent restenosis by MDCT, but in evaluable stents, sensitivity is still 86% and specificity is 98%.24When HR is reduced below 70 beats/min, image quality is improved, especially in terms of the visualization of the right coronary and left circumflex arteries, which are both significantly prone to motion artifacts (particularly at higher HR) because of their close proximity to the atrium, which is reactivated during the early diastolic phase.25For evaluation of coronary artery calcium volume with MDCT, thin-slice retrospective spiral electrocardiographic–gated scanning is desirable.26Most studies on coronary calcification have been performed using EBCT, which is still considered the “gold standard” (table 1). To image the coronary arteries with EBCT, 30–40 axial images are obtained with 3-mm slice thickness, using single-slice prospective electrocardiographic triggering in the craniocaudal direction along the full length of the heart. Rapid image acquisition at 100 ms allows accurate measurement of calcium deposits in the coronary arteries.27Quantification of coronary artery calcifications was found to be independently associated with cardiac events in a 3-yr follow-up of thousands of initially asymptomatic patients.28Noninvasive characterization and quantification of atherosclerotic plaque burden may also have important implications for the prevention of CAD progression and its complications.18For the past several years, CMRI has been considered the reference standard for assessment of left ventricular (LV) functions. However, cardiac CT is playing an increasingly important role in this evaluation. Both CT and CMRI surpass two-dimensional imaging techniques, such as standard two-dimensional echocardiography, for cardiac quantification because of their ability to generate contiguous short axis cine images, allowing for three-dimensional measurements without the use of geometric assumptions.29Postprocessing tools allow fast and semiautomatic determination of LV function parameters from MDCT data in analogy to known CMRI evaluation approaches.30Studies have demonstrated excellent correlation between cardiac CT and CMRI for LV ejection fraction, end-diastolic volume, end-systolic volume, stroke volume, and myocardial mass.30Furthermore, global and regional LV functions agree well with echocardiography, with correlation coefficients ranging from 0.91 to 0.97 for MDCT and from 0.93 to 0.98 for CMRI.7,30,31Although MDCT is not considered to be the first-line modality for assessment of LV function, it can provide a combined assessment of cardiac morphology and function without the need for additional radiation exposure in patients undergoing MDCT coronary angiography. The acquisition of images is performed according to the R–R interval. For MDCT, the image data are gated with the electrocardiogram to allow reconstruction at various times throughout the cardiac cycle. CT allows quantitative analysis of regional and global systolic function in normal and pathologic conditions by using short axis slices from the base to the apex of the heart. End-diastole and end-systole are defined as maximal and minimal LV volume, and LV ejection fraction is the difference between them.30Diastolic function can also be assessed from the rate of change of the LV volume during diastole.13Also, because temporal resolution for electrocardiographic-gated cardiac CT scans (down to 165 ms) is poorer in comparison to cine CMRI (30–40 ms), CT imaging may miss peak ejection rate or peak filling rate. However, advances in MDCT imaging that will improve temporal resolution may correct this problem.16Regional wall motion abnormalities, myocardial thinning, ventricular aneurysm, and mural thrombi in the infarcted area can all be detected by cardiac CT. Dual-phase contrast CT can detect acute MI characterized by an initial filling defect and late enhancement at the site of the damaged myocardium. Late enhancement may have the potential to distinguish viable from nonviable myocardium, and has significant prognostic value for the recovery of the myocardial wall motion and thickness after ischemia and in response to therapeutic revascularization.32In patients with previous MI, MDCT permits accurate, noninvasive assessment of coronary artery stenosis, LV function, and perfusion, assessed from a single data set.33If the myocardium supplied by the stenotic or occluded vessel is still viable, medical treatment or revascularization can be considered to reduce the risk of perioperative ischemia in the affected myocardium.Experimental studies in animals and humans demonstrated that cardiac CT could be used to assess microvascular function, although this technique is not used clinically, partially because of high radiation exposure. Evaluation of myocardial perfusion at rest and after infusion of vasodilators imposing cardiac challenge can reveal the presence of otherwise undetectable limited myocardial flow reserve, which might have a significant value for detection of borderline or very early alterations in cardiac microvascular function, as well as detecting increases in microvascular permeability that may reflect endothelial dysfunction or ischemic changes.34The use of CT scanning is limited by the need for contrast media and radiation exposure (table 2). The risks associated with contrast media administration include extravasation at the contrast injection site, allergic contrast reaction, and a decline in function, as well as and vascular In patients with administration of contrast media is media has been reduced and is than that used during angiography potential of alternative contrast such as might further decrease the various radiation are with MDCT, and scanning may allow a decrease in radiation of cardiac function and volumes may from to potentially any based on gated that data several cardiac limitations include the need to image quality in patients and the need for and physicians for acquisition and of cardiac CT data of the limitations of MDCT is the need to decrease heart rate at time of which may be in some It further the need for CT technology to acquisition time a greater volume of developed scanners such as the Dual-Source MDCT may this to temporal the number of that can be from axial CT images is limited only by gantry rotation speed and patient heart decreased ejection fraction in is associated with decreased overall postoperatively and with increased incidence of heart failure, but no has been found with main associated with cardiac events is the presence of wall motion has a low predictive is appropriate in patients who American Heart Association–American College of Cardiology clinical guidelines and who would require if no surgery were as well as in with aortic sensitivity of can be by the heart either or pharmacologically. stress test with administration of can provide information about cardiac function, ventricular and function, and a is in to 85% of maximal HR or or as wall motion abnormalities, whereas a in ejection fraction in response to administration is a of more severe CAD. has excellent negative predictive values and sensitivity but moderate specificity and is significantly and long-term cardiac risk using initial cardiac risk assessment and noninvasive testing with may the perioperative and long-term treatment of patients undergoing major vascular comparison with other noninvasive a diagnostic new of may improve cardiac risk compared with standard in patients undergoing noncardiac surgery whose functional capacity be evaluated by stress stress has a relatively low and can assess cardiac structure and function, wall thickness, aortic and the presence of However, has sensitivity for detection of single vessel disease and is to distinguish between microvascular and CAD (table because wall motion can be found in progress has been made during the past in which is used to evaluate a of heart and including CAD. CMRI is based on the of which and to an magnetic CMRI a causes deflection of the from the direction of the main magnetic The is during the of the back their in the magnetic are and data are used for image many image are for assessment of global ventricular and function, ejection fraction, stroke volume, and detection of and acute and chronic LV can be and using analysis of may find use in the clinical magnetic resonance imaging has higher temporal resolution but resolution (the ability to distinguish between two on the image) than cardiac resolution of 1.5 × 1.5 may have an CMRI for detection of because its overall accuracy in the detection of coronary artery stenosis is higher (table 2). The axial image of MDCT allows more vascular as compared with CMRI that may artifacts to sensitivity and specificity of CMRI for detection of coronary artery stenosis are and whereas of coronary segments are is noninvasive and high-quality images of the heart (table 2). However, CMRI examination be applied in patients who have a or and the presence of and stents can CMRI images and to is the of the test than an during which the patient must be CMRI is an important noninvasive tool and does not the use of potential contrast are needed to evaluate its use as a perioperative tool and its correlation with perioperative cardiac use of myocardial computed tomography and tomography has in the past two because of their in useful information about myocardial perfusion and function based on administration of an unstable with has been used for many for preoperative cardiac evaluation. the coronary response associated with testing not the HR and has been used in patients scheduled to undergo vascular surgery. However, has low and negative predictive and was not significantly associated with the incidence of perioperative MI, ischemia, or other the other the of this test was when used in patients undergoing aortic surgery whose risk could not have been on the of clinical value of imaging for preoperative cardiac assessment in high-risk has been demonstrated in patients before and vascular of myocardial with is important in patients with LV function to and the potential of revascularization can be These studies showed excellent correlation of with cardiac both perioperatively within 30 days and at long-term has high sensitivity in coronary disease but limited sensitivity for detecting significant disease and CAD (table 2). It also little functional data other than myocardial perfusion and has relatively low resolution that the quality of scanners have a maximal of approximately is required for before the performance of myocardial perfusion because the coronary effect of or is by with can be used to functional recovery of viable myocardium after coronary artery a is from a a in and with an results in of both the and the with to in the of electromagnetic radiation of two which in from each and are detected by a of radiation detectors at The difference in time the photons each radiation detector is used to detect the source of the of radiation detectors are in the gantry with million of per the imaging is useful in noninvasive quantification of myocardial flow and coronary flow reserve, and is also of detecting early disease in high-risk asymptomatic and the progression or of is to especially in patients and in undergoing remains a significant its high and limited availability currently its use as a technology of coronary angiography is well and involves injection of contrast media into the coronary artery by imaging in multiple planes. is by comparison of diameter at a stenotic site with that of a normal reference can evaluate coronary stenosis, LV function, and (table coronary angiography is an invasive technique and has a major rate of including mortality in of it may involve for the patient and is associated with other such as vascular complications for diagnostic and for complications and complications the risk of coronary angiography with that of MDCT, some risks are common to both procedures, such as an allergic contrast reaction, and exposure to whereas are to contrast media injection causes severe allergic in of risks of a of for MDCT angiography and for coronary angiography. However, the and risks and a overall risk of mortality from coronary that for MDCT angiography use of a power in a vascular with cardiac CT an additional risk of which in of the relatively significant number of negative invasive angiographies performed each the risks to this procedure by using noninvasive can greatly to the morbidity and mortality of coronary angiography. the number of negative angiographies might to significant because the of cardiac may be as as times that of cardiac evaluation of patients with or known cardiac disease for noncardiac surgery has been in the of of and The preoperative evaluation on assessment of clinical predictors, functional capacity, and the extent of the surgical The first-line to reduce perioperative morbidity and mortality include medical therapy with with HR and However, the strategy may also include of noninvasive imaging techniques that provide comprehensive and assessment of cardiac structure and In particular, in patients with restricted physical in assessment of the functional capacity is obtained using imaging with evaluation of the heart may potentially to treatment Cardiac CT is can provide coronary angiography for plaque assessment and scoring, and can assess LV function, and myocardial in a fast and relatively CT can in out significant CAD and determination of the need for invasive angiography. cardiac CT might potentially be the tool for overall evaluation of cardiac patients for noncardiac surgery. at this is no that preoperative cardiac CT scanning is to reduce perioperative studies are needed to assess the role of cardiac CT in the evaluation of patients at risk for cardiovascular disease before noncardiac surgery.

<i>Circulation</i> Editors’ Picks

Scout View X-Ray Attenuation Versus Weight-Based Selection of Reduced Peak Tube Voltage in Cardiac CT Angiography

Comprehensive Cardiac CT With Myocardial Perfusion Imaging Versus Functional Testing in Suspected Coronary Artery Disease: The Multicenter, Randomized CRESCENT-II Trial

Coronary artery disease (CAD) is a leading cause of mortality and morbidity in most developed countries [1]. CAD is a common and sometimes disabling disorder, although medication therapy, percutaneous coronary intervention and coronary artery bypass grafting have developed recently. Medical doctors need to prevent from developing acute coronary syndrome. The development of non-invasive cardiac imaging tools (particularly, cardiac computed tomography, echocardiography and so on) for the diagnostic and prognostic assessments of patients is evolving evidence for various treatment strategies. Cardiac catheterization is golden standard for the diagnosis of CAD. Although the risk of adverse events for invasive coronary angiography is generally considered to be low, potential life-threatening complications can arise, including not only coronary artery dissection, but also arrhythmia, stroke, hemorrhage, myocardial infarction (MI), and death [2]. Non-invasive imaging devices for CAD have been developing, such as echocardiography, scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI) and so on. Particularly, the development of cardiac CT is remarkable in the last 10 years. Prior report suggested a hierarchial model of efficacy to assess the contribution of diagnostic imaging to the patient management process. Level 1 is technical quality of the images. Level 2 is diagnostic accuracy, sensitivity, and specificity associated with interpretation of the images. Level 3 is whether the information produces change in the referring physician’s diagnostic thinking. Level 4 is efficacy, which concerns effect on the patient management plan. Level 5 is effect of the information on patient outcomes. Level 6 is societal costs and benefits of a diagnostic imaging technology [3]. CT imaging was introduced in 1972 [4]. The ability to obtain cross-sectional images of the computer-assisted tomography, Sir Geoffrey N. Hounsfield and Allan M. Cormack were awarded the Nobel prize in Medicine in 1979. Since a 4 detector row cardiac CT angiography was launched in 1998. Cardiac CT has experienced rapid improvement of imaging qualities with the ongoing evolution of cardiac CT. The diagnostic accuracy of the 64 detector cardiac CT to detect coronary stenoses is available. Cardiac CT is useful for the diagnosis and risk stratification of CAD. Cardiac CT presently has not been considered a routine replacement for invasive coronary angiography,

Technical performance evaluation of a human brain PET/MRI system. The magnetic field compatible positron emission tomography (PET) insert is based on avalanche photodiode (APD) arrays coupled with lutetium oxyorthosilicate (LSO) crystals and slip-fits into a slightly modified clinical 3-T MRI system. The mutual interference between the two imaging techniques was minimised by the careful design of the hardware to maintain the quality of the B (0) and B (1) field homogeneity. The signal-to-noise ratio (SNR) and the homogeneity of the MR images were minimally influenced by the presence of the PET. Measurements according to the Function Biomedical Informatics Research Network (FBIRN) protocol proved the combined system's ability to perform functional MRI (fMRI). The performance of the PET insert was evaluated according to the National Electrical Manufacturers Association (NEMA) standard. The noise equivalent count rate (NEC) peaked at 30.7 × 10(3) counts/s at 7.3 kBq/mL. The point source sensitivity was greater than 7 %. The spatial resolution in the centre field of view was less than 3 mm. Patient data sets clearly revealed a noticeably good PET and MR image quality. PET and MRI phantom tests and first patient data exhibit the device's potential for simultaneous multiparametric imaging. • Combination of PET and MRI is a new emerging imaging technology. • Evaluated brain PET/MRI enables uncompromised imaging performance. • PET/MRI aims to provide multiparametric imaging allowing acquisition of morphology and metabolism.

Background: Epicardial adipose tissue (EAT) is a metabolically active tissue. EAT volume and density (a marker of tissue inflammation), which can be quantified using cardiac computed tomography (CT), have been associated with cardiometabolic disease risk. Limited studies support that EAT has local paracrine inflammatory effects on coronary arteries, but broad biologic pathways that may improve our understanding of EAT volume and inflammation have not been evaluated. Hypothesis: We hypothesized that circulating inflammatory markers are associated with EAT and coronary artery disease. Methods: The Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) clinical trial randomized participants to CT angiography (CTA) vs. standard of care. For this study, we analyzed 1523 participants randomized to CTA with available plasma at baseline. EAT volume (indexed to BSA; cm 3 /m 2 ) and EAT density (HU, a marker of adipose tissue inflammation) were measured using a validated deep-learning algorithm on cardiac CT images. We compared 502 unique proteins (Olink) with EAT measures using linear regression, adjusted for age, sex, self-reported race, BMI, diabetes, LDL-C, HDL-C, triglycerides and creatinine. Results: Of 502 proteins, 124 (24.7%) were associated with EAT volume (FDR p&lt;0.05). Of these, 100 were positively associated, including markers of hepatic glucose homeostasis (PRSS8, FGF-21) and 24 were inversely associated, including a marker of vascular calcification (OMD) ( Figure ). In models for EAT density, 70 proteins were significant (13.9%); 18 were positively associated and 52 inversely associated, including metabolic and inflammatory proteins (LEP, HGF, INHBC, IL-1ra). Overall, 57 overlapping proteins were associated with both EAT volume and EAT density. 13 of these proteins were concordantly associated with a composite high-risk coronary phenotype in PROMISE, including higher levels of INHBC, ACE2, GDF-15, CTSD, FGF-21, CDHR2, and MLN and lower levels of BOC, ADGRG2, LPL, OMD, CLUL1 and APLP1. Conclusions: In a large clinical trial of CTA, we have identified circulating metabolic and inflammatory proteins associated with EAT volume and inflammation independent of clinical variables, many of which are also associated with coronary artery disease. These findings highlight proteomic pathways which may mediate the known association between EAT and cardiovascular disease, and further highlight biomarkers as potential prognostic and therapeutic targets.

Assessment of Anomalous Coronary Arteries by Imagers and Surgeons: Comparison of Imaging Modalities

For decades, the identification of significant luminal narrowing has been the hallmark to characterize the presence and extent of coronary artery disease. However, it is now known that characterizations of systemic atherosclerosis burden and inflammation, as well as the local quality of plaque composition and morphology, allow better characterization of coronary artery disease and thus may allow improved prediction of adverse cardiovascular events. Plaque characterized histologically as a thin-cap fibroatheroma (ie, an atheroma with a thin fibrous cap, an underlying lipid-rich necrotic core, and inflammatory activity) has been recognized as representing vulnerable or high-risk plaque. Positron emission tomography (PET) and cardiac computed tomography (CT) are noninvasive modalities that provide metabolic (PET) and morphologic (CT) information about atherosclerotic plaque. PET allows the quantification of the uptake of fluorine 18 fluorodeoxyglucose (FDG) within the arterial wall, which provides a measure of macrophage activity within atheromatous plaque. Coronary CT allows the depiction of plaque morphology and composition. Thus, integrated imaging with PET and CT (PET/CT) permits coregistration of FDG activity with the presence and morphology of plaque and may lead to improved characterization of vulnerable plaque or vulnerable patients, or both. This review details the methods and principles of cardiac FDG PET and coronary CT and provides an overview of the research, with an emphasis on the identification and characterization of vulnerable plaque.

ACR Clinical Statement on Noninvasive Cardiac Imaging

To investigate the shape of right auricule on 256-slice computed tomography (CT). Five hundred people (250 men, age range 16-84years) who had cardiac multidetector CT angiography were recruited in this study. All patients had normal sinus rhythm with normal blood pressure (<140/90mmHg for systolic/diastolic pressure). The morphology of the right auricule was studied and compared after reconstruction of the raw images. All patients successfully had cardiac CT angiography (100%), and the right auricule morphology was divided into five types and nine subtypes, including Type I of triangular shape (Ia and Ib), Type II of M shape (IIa and IIb), Type III of L shape (IIIa and IIIb), Type IV of reverse L shape (IVa and IVb), and Type V of balanced shape. The most common type of right auricule is Type IV (28.4%) followed by Type II (24.0%), whereas the least common is Type V (11.0%). Type Ia was present significantly (P<0.0001) more frequently in females than in males, whereas Type IIa significantly (P=0.042) more frequently in males than females. No other significant (P>0.05) sex difference existed in the constitution ratio of the types. The normal angle was greater in Type Ib than in Ia. The greater the normal angle in Type I, the greater the deviation of the right auricule tip towards the left. A good understanding of the right auricule anatomical morphology can better guide atrial pacing, radiofrequency ablation and other surgical procedures while preventing possible intra-procedural complications.

Recent advancements in molecular biology, biotechnology, chemistry/radiochemistry, artificial intelligence, and imaging techniques have significantly propelled the field of cardiovascular molecular imaging. This review aims to provide a comprehensive overview of the current state of cardiovascular positron emission tomography (PET) imaging and cardiac computed tomography (CT), exploring their roles in elucidating molecular and cellular processes, enabling early disease detection, and guiding novel therapeutic interventions for cardiovascular conditions. Cardiovascular PET imaging strives to uncover molecular and cellular events preceding visible anatomical manifestations or physiological changes. Meanwhile, cardiac CT has evolved into a multifaceted modality, offering insights into both anatomy and function. Utilizing advanced CT technologies allows for a thorough evaluation, encompassing fractional flow reserve, perfusion imaging, pericoronary adipose tissue attenuation, atherosclerotic plaque characterization, cardiomyopathies, structural cardiac abnormalities, and congenital heart anomalies. The emergence of hybrid imaging, combining PET and CT, presents innovative prospects in cardiology. This approach enables the simultaneous assessment of cardiac perfusion and coronary anatomy in a singular scan, providing complementary insights relevant to potential coronary artery disease. Despite the substantial potential impact, operational familiarity with this hybrid tool remains limited, and its integration into routine clinical practice warrants further exploration. In summary, the review underscores the transformative impact of recent technological advancements on cardiovascular molecular imaging. The integration of PET and CT, along with their individual capabilities, holds promise for early disease detection and informed clinical decision-making. While acknowledging the potential of hybrid imaging, it emphasizes the need for increased operational familiarity and continued exploration to facilitate its seamless integration into routine clinical practice. The insights gained from this review contribute to the ongoing dialogue in the field, offering a foundation for future research and advancements in cardiovascular imaging.

Myocardial fat is often seen at cardiac computed tomography (CT) and magnetic resonance (MR) imaging of healthy adults and patients with myocardial diseases. Physiologic myocardial fat develops with aging and is commonly seen at CT in the anterolateral right ventricular (RV) free wall and RV outflow tract with normal or thickened RV myocardium and a normal-sized RV in elderly patients. Pathologic conditions with myocardial fat include healed myocardial infarction (MI); arrhythmogenic RV cardiomyopathy or dysplasia (ARVC); and others, such as cardiac lipoma, lipomatous hypertrophy of the interatrial septum, tuberous sclerosis complex, dilated cardiomyopathy, and cardiomyopathy with muscular dystrophy. In patients with healed MI, CT and MR imaging show fat in left ventricular myocardium that is of normal thickness or thin and follows the distribution of the coronary artery; CT often depicts fat in mostly subendocardial regions. In patients with ARVC, characteristic CT and MR imaging findings include a thin RV outflow tract and free wall caused by subepicardial fatty infiltration; fat in the RV moderator band, trabeculae, and ventricular septum; and RV enlargement and wall motion abnormality. Recognition of patient age, characteristic locations of myocardial fat, myocardial thickness, and ventricular size helps in differentiating physiologic and pathologic myocardial fat at cardiac imaging; findings of wall motion abnormality and late gadolinium enhancement at MR imaging help narrow the diagnosis.

Cardiac CT angiography in current practice: An American society for preventive cardiology clinical practice statement✰

The aim of our study was to investigate the feasibility of single-beat prospective electrocardiogram (ECG)-gated cardiac computed tomography (CT) using a 256-detector row wide-volume CT scanner for functional and anatomical evaluation of the aortic valve (AV) and coronary arteries in patients with AV disease. A total of 50 patients who underwent cardiac CT scan with a wide-volume 256-detector row CT scanner for the evaluation of AV and aorta were retrospectively enrolled. Cardiac CT was performed using the prospective ECG-gated acquisition mode, and AV image quality was analyzed using a four-point grading system. Severity of aortic stenosis (AS) and aortic regurgitation (AR) were assessed by CT and correlated to that assessed by transthoracic echocardiography (TTE) based on kappa statistics (κ). Estimated radiation exposure was assessed. Among 50 patients, 44 underwent cardiac CT with single-beat acquisition. The median image quality score of AV was 3.0 on the systolic phase and 4.0 on the diastolic phase. Severity of AS and AR by CT showed moderate agreement with TTE. The mean effective radiation dose was 3.75 ± 1.43mSv for CT angiography. Using 256-detector row wide-volume CT, the single-beat cardiac CT is feasible for evaluation of AV disease and the coronary arteries, with acceptable image quality and a low radiation dose of 3.75mSv.