Jabi E. Shriki

Identifying, Characterizing, and Classifying Congenital Anomalies of the Coronary Arteries

The clinical manifestations of coronary artery anomalies vary in severity, with some anomalies causing severe symptoms and cardiovascular sequelae and others being benign. Cardiovascular computed tomography (CT) has emerged as the standard of reference for identification and characterization of coronary artery anomalies. Therefore, it is important for the reader of cardiovascular CT images to be thoroughly familiar with the spectrum of coronary artery anomalies. Hemodynamically significant anomalies include atresia, origin from the pulmonary artery, interarterial course, and congenital fistula. Non-hemodynamically significant anomalies include duplication; high origin; a prepulmonic, transseptal, or retroaortic course; shepherds crook right coronary artery; and systemic termination. In general, coronary arteries with an interarterial course are associated with an increased risk of sudden cardiac death. Coronary artery anomalies that result in shunting, including congenital fistula and origin from the pulmonary artery, are also commonly symptomatic and may cause steal of blood from the myocardium. Radiologists should be familiar with each specific variant and its specific constellation of potential implications.

Incidental Myocardial Infarct on Conventional Nongated CT: A Review of the Spectrum of Findings With Gated CT and Cardiac MRI Correlation

OBJECTIVE Myocardial infarctions (MIs) are frequently evident on routine chest or abdominal CT, even when studies are not performed for cardiac-specific indications. However, the telltale signs of an MI may be easily overlooked. Herein, we present the spectrum of appearances of MIs, including areas of fat attenuation, myocardial calcifications, focal areas of wall thinning or aneurysm formation, and perfusion abnormalities. Thrombi, especially when present at the apex of the left ventricle, may also suggest an MI. CONCLUSION The increased use of CT in the evaluation of patients for a variety of indications gives the radiologist the unique opportunity to recognize findings consistent with MI in patients who may not have a prior diagnosis of ischemic heart disease.

Does Coronary Calcium Score Predict Future Cardiac Function? Association of Subclinical Atherosclerosis with Left Ventricular Systolic and Diastolic Dysfunction at MR Imaging in an Elderly Cohort

PURPOSE To evaluate subclinical atherosclerosis measured by using coronary artery calcium (CAC) as a predictor of future left ventricular (LV) systolic and diastolic function in asymptomatic elderly participants. MATERIALS AND METHODS The institutional review boards of the University of Southern California and the Harbor University of California Los Angeles Research and Education Institute (where the South Bay Heart Watch study was initially conducted) approved this HIPAA-compliant study of 386 participants (mean age, 75.2 years) from among the original 1461 participants in the longitudinal South Bay Heart Watch prospective investigation of subclinical atherosclerosis. CAC at computed tomography was correlated with LV ejection fraction (LVEF), regional wall motion abnormalities (RWMAs), and peak filling rate (PFR) assessed a mean of 11.4 years ± 0.6 (standard deviation) later with cardiac magnetic resonance imaging. Analysis of variance and covariance testing was performed with the Wald test, testing for trends across the CAC groups. Covariates included age, level of total cholesterol, level of high-density lipoprotein cholesterol, systolic blood pressure, use of lipid-lowering medication, and smoking status. RESULTS Mean LVEF was 60.3% ± 9.9, with 11 (2.8%) of 386 participants having an LVEF of less than 40%. Forty-six (11.9%) of 386 participants had RWMAs. Higher CAC scores were associated with slightly lower LVEF (P for trend = .04) and a greater percentage of participants with decreased PFR (P for trend = .47) and RWMAs (P for trend = .01). After age- and risk factor-adjustment, only RWMA (P = .05) was associated with higher CAC. RWMAs were associated with significantly (P < .001) lower mean LVEF and PFR. Nineteen (41%) of 46 participants with RWMAs had documented Q-wave myocardial infarction, and three (7%) underwent coronary revascularization. CAC scores of 100 or greater were associated with a 2.2-fold (95% confidence interval: 1.30, 3.75) increase in RWMA (P < .001). CONCLUSION Subclinical atherosclerosis assessed by using CAC is associated with an increased future likelihood of RWMA, as a marker of previous and possible subclinical coronary artery disease.

Left atrial appendage: structure, function, imaging modalities and therapeutic options

The left atrial appendage (LAA) is a common source of cardiac thrombus formation and systemic embolism. It is a ‘blind’ cul-de-sac and multilobed anatomic structure with variable anatomy. Therefore, it requires detailed evaluation in multiple imaging planes to evaluate for thrombus formation. Transesophageal echocardiography is the most common imaging modality used to rule out LAA thrombus. Doppler imaging enhances understanding of LAA function. 3D imaging of the LAA with live 3D transesophageal echocardiography, computed tomography and MRI may be further utilized for thrombus detection, as well as for sizing, and the development of new transcatheter occluder devices for LAA to prevent thrombus formation is needed.

Chemical Shift Artifact on Steady-State Free Precession Cardiac Magnetic Resonance Sequences as a Result of Lipomatous Metaplasia: A Novel Finding in Chronic Myocardial Infarctions

BACKGROUND Because balanced steady-state free precession (SSFP) sequences are opposed-phase gradient echo techniques, linear low signal due to chemical shift artefact is observed at fat-water interfaces. We observed that some patients with chronic myocardial infarctions had linear low signal along the inner myocardial wall in areas of infarction, which we postulated was due to chemical shift artefact, as a result of lipomatous metaplasia. The purpose of this retrospective review was to evaluate whether subendocardial low signal on SSFP, likely related to chemical shift artifact, could be used to identify chronic myocardial infarctions. METHODS Of 128 patients who underwent cardiac magnetic resonance, 79 with myocardial infarctions were included in this retrospective study. RESULTS Of the 79 patients, 35 (44%) demonstrated areas of linear subendocardial decreased signal. In 16 of those 35 (46%), the infarcts were confirmed as fatty by correlation with CT. In 29 of 35 (83%) of these patients, the infarcts were likely chronic based on fixed wall thinning to less than 4 mm. In 3 patients, chemical shift artifact due to lipomatous metaplasia was also confirmed with conventional in-phase and opposed-phase T1-weighted sequences. Subendocardial chemical shift artefacts were not seen in any of the 19 patients with known, acute infarcts included in this series. Aneurysms were more common when subendocardial chemical shift artefact was present (22 of 35), in comparison to patients who did not have this finding (10 of 44, P = 0.02). CONCLUSIONS Identification of linear subendocardial chemical shift artefacts on SSFP sequences is a sign of lipomatous metaplasia in chronic myocardial infarcts and is associated with an increased incidence of ventricular aneurysms.

Repair of a high-flow iliac arteriovenous fistula using a thoracic endograft.

Open surgical repair of iliac arteriovenous fistulas is associated with significant morbidity and mortality, making endovascular repair an attractive alternative. This report describes a 39-year-old man who was admitted with two-pillow orthopnea, edema, and fatigue. He had sustained a gunshot wound to the pelvis 13 years previously. Six years after the gunshot wound, he was diagnosed with cardiomegaly and high-output congestive heart failure. A magnetic resonance angiography documented a large pelvic arteriovenous fistula. A diagnostic contrast angiogram confirmed a high-flow fistula between the left distal main internal iliac artery and left common iliac vein. A Gore TAG thoracic endoprosthesis (W. L. Gore and Assoc, Flagstaff, Ariz) was used to repair this large, high-flow internal iliac artery-common iliac vein arteriovenous fistula.

Anomalous coronary arteries: cardiovascular computed tomographic angiography for surgical decisions and planning.

Cardiovascular computed tomographic angiography (CCTA) provides an understanding of the three-dimensional (3D) coronary artery anatomy in relation to cardiovascular thoracic structures important to the surgical management of anomalous coronary arteries (ACAs). Although some ACA variants are not clinically significant, others can lead to ischemia/infarction, related acute ventricular dysfunction, ventricular arrhythmias, and sudden cardiac death. The CCTA is important to surgical decision making, as it provides noninvasive visualization of the coronary arteries with (1) assessment of origin, course, and termination of coronary artery anomalies in the context of 3D thoracic anatomy, (2) characterization of anatomy helpful for differentiation of benign versus hemodynamically significant variants, (3) identification of other cardiothoracic anomalies, and (4) detection of coronary artery disease. High-risk ACA anatomy in the appropriate clinical setting can require surgical intervention with decisions including minimally invasive versus open sternotomy approach, correction via reimplantation of a coronary artery, alteration of the ACA course without reimplantation, or bypass of an ACA. Given the rarity of ACA, there is limited data in the literature, and significant controversy related to the management issues. The management of ACA requires comprehensive clinical history, thorough assessment of cardiac function, and detailed anatomic imaging. Future studies will need to address the long-term outcome based on detailed assessment of original anatomy and surgical approach.

A Novel Reporting System to Improve Accuracy in Appendicitis Imaging

OBJECTIVE The purpose of this study was to ascertain if standardized radiologic reporting for appendicitis imaging increases diagnostic accuracy. MATERIALS AND METHODS We developed a standardized appendicitis reporting system that includes objective imaging findings common in appendicitis and a certainty score ranging from 1 (definitely not appendicitis) through 5 (definitely appendicitis). Four radiologists retrospectively reviewed the preoperative CT scans of 96 appendectomy patients using our reporting system. The presence of appendicitis-specific imaging findings and certainty scores were compared with final pathology. These comparisons were summarized using odds ratios (ORs) and the AUC. RESULTS The appendix was visualized on CT in 89 patients, of whom 71 (80%) had pathologically proven appendicitis. Imaging findings associated with appendicitis included appendiceal diameter (odds ratio [OR] = 14 [> 10 vs < 6 mm]; p = 0.002), periappendiceal fat stranding (OR = 8.9; p < 0.001), and appendiceal mucosal hyperenhancement (OR = 8.7; p < 0.001). Of 35 patients whose initial clinical findings were reported as indeterminate, 28 (80%) had appendicitis. In this initially indeterminate group, using the standardized reporting system, radiologists assigned higher certainty scores (4 or 5) in 21 of the 28 patients with appendicitis (75%) and lower scores (1 or 2) in five of the seven patients without appendicitis (71%) (AUC = 0.90; p = 0.001). CONCLUSION Standardized reporting and grading of objective imaging findings correlated well with postoperative pathology and may decrease the number of CT findings reported as indeterminate for appendicitis. Prospective evaluation of this reporting system on a cohort of patients with clinically suspected appendicitis is currently under way.

Classic Images: Coronary Computed Tomographic Angiography

A number of congenital and acquired conditions may affect the coronary arteries, ranging from very common entities, such as atherosclerotic disease, to very rare coronary anomalies. Some of the conditions that affect the coronary arteries are unique in the body. As a result, readers of cardiac computed tomography are faced with several unique challenges in classifying and stratifying a wide array of diseases. Herein, we discuss some of the technical aspects of coronary computed tomographic angiography and review the spectrum of coronary abnormalities that may be detected with this modality. The typical imaging findings of common and uncommon coronary disease states will be demonstrated.

Systemic lupus erythematosus coronary vasculitis demonstrated on cardiac computed tomography

Coronary artery aneurysms are an uncommon manifestation of systemic lupus erythematosus (SLE), with only 14 cases reported previously in the literature. Herein, we report a 29-year-old woman with SLE who developed clinical and serologic evidence of an SLE flare and presented with chest pain and elevated serum troponin-T level. Cardiac computed tomography was performed and demonstrated fusiform aneurysmal enlargement of the proximal and middle portions of the coronary arteries and a beaded appearance of the distal coronary arteries. Extensive intercostal artery aneurysms were also noted. Several areas of abnormal myocardial perfusion were also noted. The patient improved after treatment with steroid pulses and cyclophosphamide. This case report is the first description of the appearance of lupus coronary vasculitis on cardiac computed tomography.