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Classic Images: Cardiac Computed Tomography
Classic Images: Cardiac Computed Tomography Joanne D. Schuijf, PhD, Lucia J. Kroft, PhD, MD, Albert de Roos, PhD, MD, and Jeroen J. Bax, PhD, MD Abstract: Cardiac computed tomography (CT) has evolved into a valuable clinical tool for cardiac evaluation. Cardiac CT is increasingly used for imaging of the coronary arteries for the evaluation of (suspected) coronary artery disease, but many other cardiac structures may be the topic for CT investigation. This article reviews general indications for cardiac CT imaging. Common variants and pathologies of the cardiovascular system are illustrated by clinical examples. (Curr Probl Cardiol 2009;34: 277-295.) ardiac computed tomography (CT) has evolved into a valuable clinical tool for cardiac evaluation. Cardiac CT is increasingly used for imaging of the coronary arteries for the evaluation of (suspected) coronary artery disease, but many other cardiac structures may be the topic for CT investigation. This article reviews general indications for cardiac CT imaging. Common variants and pathologies of the cardiovascular system are illustrated by clinical examples.
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Coronary Anatomy With the introduction of electron-beam computed tomography and, more recently, multi-detector row CT, noninvasive visualization of the coronary arteries with high resolution has become possible. Initially coronary artery disease could be identified by non-contrast-enhanced Jeroen J. Bax has research grants from Medtronic (Tolochenaz, Switzerland), Boston Scientific (Maastricht, the Netherlands), BMS medical imaging (N. Billerica, MA), St. Jude Medical (Veenendaal, the Netherlands), Biotronik (Berlin, Germany), GE Healthcare (St Giles, UK), and Edwards Lifesciences (Saint-Prex, Switzerland). All images in this article were obtained by helical 16-MDCT or 64-MDCT (Toshiba Aquilion 16CFX or Aquilion 64 CT scanner, Toshiba Medical System, Otawara, Japan) or by volumetric 320-MDCT (Toshiba, Aquilion one, Tochigi-ken, Japan). Curr Probl Cardiol 2009;34:277-295. 0146-2806/$ – see front matter doi:10.1016/j.cpcardiol.2009.01.004
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FIG 1. Coronary calcium. 320-MDCT. Noncontrast axial image showing extensive calcifications (arrowheads) in the left main and left anterior descending coronary artery in an asymptomatic 75-year-old patient with hypercholesterolemia and hypertension.
FIG 2. Normal coronary angiogram. 320-MDCT. Curved multiplanar reconstructions of the left anterior descending (A), left circumflex (B), and right coronary artery (C), respectively, of a 72-year-old female with atypical chest pain and an elevated risk profile (hypertension, hypercholesterolemia, and family history of coronary artery disease). CT angiography showed only minor wall irregularities and absence of significant stenosis.
coronary calcium scoring. Extensive data are available supporting the prognostic value of the presence and extent of calcifications in predicting future cardiovascular events.1 More recently, direct coronary angiography has also become possible. High accuracies have been demonstrated in the detection of significant coronary stenoses as compared to invasive coronary angiography.2 The technique appears to be particularly valuable in 278
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FIG 3. Significant coronary stenosis. 320-MDCT. Curved multiplanar reconstruction of the left anterior descending coronary artery of a 56-year-old female, revealing a nonsignificant calcified plaque (arrowhead) in the proximal part of the artery, whereas a significant stenosis can be observed more distally (arrow).
the exclusion of significant coronary artery disease. In addition, the technique allows accurate assessment of coronary anomalies and fistula by providing detailed information on both their origin and their course3,4 (Figs 1-6).
Coronary Stents, Bypass Grafts, and Veins The assessment of patients with previous stents may be more difficult with CT as the metallic content can give rise to artifacts. At present, therefore, only assessment of patients with relatively larger stents (⬎ 3.0-mm-diameter) can be recommended.5 In contrast, for the assessment of coronary bypass grafts, the three-dimensional nature of Curr Probl Cardiol, June 2009
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FIG 4. Benign coronary artery anomaly. 64-MDCT. Seventy-one-year-old male referred for CT angiography for suspected coronary anomaly of the left coronary artery. (A) On the maximum intensity oblique coronal multiplanar reconstruction the origin of the left coronary artery from the right coronary cusp (separately from the right coronary artery) can be observed. (B) Axial image showing the anomalous retro-aortic course of the left coronary artery (arrow) running between the aorta and left atrium to the anterior ventricular wall. (C, D, and E) Curved multiplanar reconstructions in different orientations further illustrate the origin and course of the coronary anomaly. This anomaly with retro-aortic course is considered benign. Ao, aorta; LA, left atrium; LCA, left coronary artery; LV, left ventricle; RCA, right coronary artery.
FIG 5. Malignant coronary artery anomaly. 64-MDCT. Three-dimensional volume-rendered reconstruction (A) showing an anomalous right coronary artery (arrow) arising from the left coronary cusp and coursing between the aorta (#) and pulmonary trunk (*). On the consecutive axial images (B, C), the interarterial course between the aorta and pulmonary trunk with reduction of the lumen at the origin is further illustrated. These anomalous interarterial arteries often arise with an acute angle and are somewhat narrowed in the proximal part. This anomaly is considered malignant because the interarterial course can result in compression (pinching off) of the coronary artery and reduction of blood flow, particularly during exercise. Patients are at risk for exercise-induced ischemia, infarction, and sudden death. 280
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FIG 6. Coronary artery fistula. 320-MDCT. Axial images of a 67-year-old female with large coronary artery fistula (arrows, A-D) from the right coronary artery to the coronary sinus with retrosternal course and course through the right and left atrio-ventricular groove. Note that the size of the fistula (arrows, A) is even larger than the size of the aortic root (A). Over 90% of fistulas drain into the low-pressure right-sided venous circulation causing a left-to-right shunt. Bypassing the myocardial capillary bed causes reduction in myocardial blood flow distal to the site of the anomalous connection. Therefore, the myocardium beyond the fistula’s origin is at risk for ischemia, most evident during exercise.22 This patient had atrioventricular valve regurgitation additional to the large fistula and showed signs of congestive cardiac failure; note the bilateral pleural effusion (A-D) and dilated hepatic veins (D).
CT offers clear advantages.6 Finally, visualization of the cardiac venous anatomy with CT may be useful in the evaluation of patients before cardiac resynchronization therapy and may predict procedural success of transvenous left ventricular lead implantation7,8 (Figs 7-10).
Cardiac Anatomy and Structure CT with intravenous contrast allows high-resolution imaging of cardiac anatomy and structures. Retrospectively, the images can be viewed in all planes (including the established cardiac planes), facilitating accurate assessment of atrial and ventricular dimensions. Also, CT is frequently Curr Probl Cardiol, June 2009
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FIG 7. Coronary stents. 64-MDCT. Curved multiplanar reconstructions of the left anterior descending coronary artery of two patients with previous stent implantation following anterior myocardial infarction. In (A) two patent bare metal stents (partially overlapping) with a diameter of 3.5 mm can be observed, while in (B) a patent drug-eluting stent (diameter 3.5 mm) is present. Note that also the presence of distal runoff can be observed, although this should not be used as the only criterion for stent patency.23 While CT angiography allows accurate ruling out of in-stent restenosis in larger stents (diameter ⬎ 3.0 mm), obtaining an accurate diagnosis remains challenging in smaller stents.
FIG 8. Coronary bypass graft stenosis. 64-MDCT. Coronal (A) and three-dimensional volumerendered (B) CT images showing severe graft disease in a 68-year-old male. Occlusion of the venous graft to the right coronary artery (arrowheads) was identified, while the venous graft to the left circumflex coronary artery (white arrow) was also shown to be proximally occluded. Note the severely diseased native right coronary artery (B, black arrows). Invasive coronary angiography for coronary bypass grafts is frequently technically more difficult than for native vessels with longer procedure times. In contrast, individual bypass grafts can be located more easily with CT. However, severe calcifications and extensive atherosclerotic disease of the native coronary arteries, frequently observed in this patient population, can impair evaluation of the native coronary segments. Ao, aorta; LV, left ventricle.
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FIG 9. Cardiac venous anatomy. 64-MDCT. Three-dimensional volume-rendered reconstructions, showing a posterior (A), lateral (B), and anterior (C) view of the heart. In addition to the coronary arteries, the cardiac venous system is clearly visible. In (A), the coronary sinus (CS) and its first and second tributaries can be observed. The first tributary is the posterior interventricular vein (PIV), which runs in the posterior interventricular groove. The second tributary is the posterior vein of the left ventricle (PVLV). The great cardiac vein (GCV) continues in the atrioventricular groove (B). Only a small left marginal vein (LMV) can be observed (arrow). Finally, the GCV continues in the anterior interventricular groove as the anterior interventricular vein (AIV, C). Noninvasive visualization of cardiac venous anatomy may be of value in candidates for cardiac resynchronization therapy.7 AIV, anterior interventricular vein; CS, coronary sinus; GCV, great cardiac vein; LMV, left marginal vein; PIV, posterior interventricular vein; PVLV, posterior vein of the left ventricle.
FIG 10. Thebesian valve. 320-MDCT. Axial (A) and coronal (B) images of a 77-year-old female patient showing the location of the Thebesian valve (arrowheads) of the coronary sinus. Note the difference in contrast indicated by the arrowheads, indicating the location of the valve. The presence of a Thebesian valve, which is a remnant of the embryonic right valve and occurs with variable formation at the origin of the coronary sinus, may obstruct or complicate cannulation of the coronary sinus ostium and can thus be the cause of an unsuccessful transvenous approach for left ventricular lead implantation.8
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FIG 11. Left atrial appendage filling defect representing pseudothrombus. 320-MDCT. Axial image of a 59-year-old male, pre-radiofrequency ablation therapy for treatment of atrial fibrillation. A filling defect can be observed in the tip of the left atrial appendage (LAA), suspected for intracardiac thrombus (arrow). However, echocardiographic evaluation excluded thrombus. The filling defect is explained by blood stasis due to poor contractile function of the left atrial appendage in patients with atrial fibrillation, which seldom occurs in patients without atrial fibrillation.10,24 Nevertheless, true atrial or atrial appendage thrombus is also highly associated with atrial fibrillation.24 Ao, aorta; LAA, left atrial appendage; RVOT, right ventricular outflow tract.
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FIG 13. Healed myocardial infarction with calcified apex aneurysm and fatty replacement. 64-MDCT. Short-axis (A) and axial (B) images of a 66-year-old man with history of a 15-year-old anterior myocardial infarction. A dilated left ventricle with myocardial thinning in the anterior and septal regions with subendocardial low-attenuation nonenhancing rim with attenuation value of ⫺70 HU can be observed. In addition, dense calcifications, indicating old calcified myocardial infarction at the midventricular and apical level, are present. The dark rim consists of fat deposition that occurs as an age-related process in this old myocardial infarction. Small foci of intramyocardial fat can be observed in healthy persons as well as in the left ventricular myocardium (more often in females than males) and in the right ventricular myocardium (increasing with age) that typically involves the endocardial aspect of the myocardium. Fatty replacement of myocardial tissue is more often observed in patients with infarction more than 3 years old.25
used in the case of suspected intracardiac shunts such as those caused by interatrial and interventricular defects.9 In addition, the technique can be helpful in the identification of intracardiac masses, such as thrombi and tumors. However, filling defects at early-phase CT suggesting thrombus should be confirmed by delayed-phase CT, echocardiography, or magnetic resonance imaging. Frequently, the appearance could also be due to blood stasis caused by poor contractile function rather than true thrombus formation10 (Figs 11-17).
Fig. 12. Apical thrombus in dilating cardiomyopathy. 64-MDCT. Axial images of a 43-year-old male with known dilating cardiomyopathy. Note the severely dilated left ventricle (LV, A) and the filling defect in the LV apex (arrow, B) due to apical thrombus. LV thrombi are located mainly at the apex and only occur with an abnormally contracting left ventricular wall. Thrombi occur in aneurysms, in the area adjacent to healed myocardial infarction, and with idiopathic dilated cardiomyopathy with poor wall motion. Thrombus is the most frequent intracardiac mass and its major risk is systemic embolization.
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FIG 14. Lipomatous hypertrophy of the interatrial septum. 64-MDCT. Axial images of a 76-year-old male with lipomatous atrium septum. Thick low-attenuating interatrial septum consisting of excessive deposition of fatty tissue where the fossa ovalis is spared (arrow, A), usually causing a “dumbbell” appearance. (B) Lower level. Lipomatous hypertrophy of the interatrial septum exceeding 1 cm thickness is present in about 3% of patients. It is a benign disorder that has been associated with pulmonary emphysema and may cause arrhythmias.26
FIG 15. Ventricular diverticulum and small atrium septum defect. 64-MDCT. Axial images in a 59-year-old female, showing incidental finding of a small diverticulum (arrow, A) at the base of the left ventricle near the right ventricular insertion point and was associated with an atrium septum defect (arrow, B), where a small left-to-right shunt is visible as little contrast leak from the left atrium (LA) to the right atrium (RA). Diverticula are not very frequent with an incidence found at autopsy of about 0.4% in patients who died of cardiac disease. On CT, diverticula have been found with an incidence of 2.2%, where most are observed along the inferior or inferoseptal regions of the left ventricle, primarily at the site of right ventricular insertion.27 The majority are completely closed at systole. However, when located at the interventricular septum, contrast outpouchings may rather be remains of a closed muscular ventricular septum defect. There is some debate whether all described diverticula---with higher incidence found on CT than at pathology---are true diverticula (outbulgings of hollow organs) or rather crypts. Crypts penetrating into the muscular wall located mainly at the mid and basal inferoseptal segments have been described to be present in most hypertrophic cardiomyopathy mutation carriers and may precede development of left ventricular hypertrophy.28 LA, left atrium; RA, right atrium.
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FIG 16. Left atrium diverticulum. 64-MDCT. Axial image of a 53-year-old man showing a small smooth-walled atrium diverticulum located at the typical location of the atrial roof directly posterior to the aortic root near the venoatrial junction of the right superior pulmonary vein (arrow). This is a common finding present in about 16-30% of the population.29,30 It has been speculated that such diverticulum may represent an incompletely regressed remnant of a cardinal vein during embryologic development.29 Possibly, atrium diverticula may be clinically relevant due to potentially decreased efficacy of ablation therapy if the diverticulum causes a gap in the line of block, or theoretical risk of thrombus.29
Pericardial Abnormalities The pericardium can be recognized on CT as a thin low-attenuation structure that lies between the epicardial and pericardial fat. Although echocardiography and chest radiography are used for the initial evaluation of pericardial disease, CT offers the advantage of high-resolution images with lower operator dependence as compared to echocardiography.11 The excellent delineation of the pericardium can facilitate diagnosis of constrictive pericarditis.11 Other pericardial diseases, such as pericardial effusion and pericardial cysts, can be easily recognized on CT as well12 (Figs 18 and 19). Curr Probl Cardiol, June 2009
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FIG 17. Cardiac tumor. 16-MDCT. Left ventricle (LV) short-axis multiplanar reformation of a 48-year-old male patient who was HIV⫹, showing extensive right ventricular (RV) thickening (*) due to a massively infiltrating tumor that also extended into the right atrium. Also, note the nodular thickening of the pericardium (arrows). Pathology investigation of biopsies taken from the right ventricle and right atrium were diagnostic for B-cell non-Hodgkin lymphoma. Metastases or direct extension of malignant extracardiac tumors have a 40-fold higher frequency than primary tumors. Non-Hodgkin’s lymphoma is present in about 3% of patients with AIDS, where secondary cardiac involvement is not uncommon but is often undetected due to nonspecific symptoms.31 LV, left ventricle; RV, right ventricle.
Cardiac Valves Although echocardiography remains the primary technique for evaluation of valvular heart disease, emerging data show the feasibility of CT to study aortic and mitral valve anatomy.13-15 Particularly in the setting of percutaneous valve repair or replacement, the detailed information on valve morphology, dimensions, and surrounding structures obtained by CT may be highly relevant and help in avoiding complications during the procedure.16,17 By using multiphase data sets, the leaflet or cusp motion can be evaluated in cine-loops, providing even some crude information on valvular function13-15 (Figs 20 and 21).
Thorax and Large Vessels Although in the past, invasive angiography served as the gold standard for the evaluation of aortic aneurysms and dissections, the 288
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FIG 18. Calcified constrictive pericarditis. 64-MDCT. Axial images of a 58-year-old male with thickened calcified pericardium (arrowheads) causing constrictive pericarditis (A-D). Note the extensive calcifications and calcified lump compressing the anterior right ventricle wall (D, arrow). While calcified thickened pericarditis is suggestive for tuberculous etiology,32 other well-known causes are postmediastinal irradiation injury and post open-heart surgery. In the Western world, however, idiopathic constrictive pericarditis is most common.32 Constrictive pericarditis can cause distortion of the ventricles with narrow, compressed appearance of both ventricles and dilated right atrium and caval veins.33 All signs were present in this patient at chest CT. Patient had signs of heart failure with pleural effusion and dilated caval veins.
use of CT angiography is currently preferred. The technique allows accurate evaluation of aneurysm size as well as classification of dissection type, which has important prognostic and therapeutic implications.18 CT is also the first-choice technique in evaluating patients with suspected pulmonary emboli, allowing simultaneous evaluation of right ventricular morphology.19 Finally, CT angiography can be useful in identifying variants in pulmonary vein anatomy before radiofrequency catheter ablation for atrial fibrillation.20 Following this procedure, the technique may identify complications such as pulmonary vein stenosis21 (Figs 22-26). Curr Probl Cardiol, June 2009
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FIG 19. Pericardial cyst. 64-MDCT. Axial image of a 41-year-old male showing a large homogenous 12.5 ⫻ 4.3 ⫻ 10.0 cm mass (*) with low-attenuation values at the right heart border, with smooth contour, without visible wall, and without enhancement. Characteristics are consistent with cyst with the location in the anterior cardiophrenic angle typical for pericardial cyst.12
FIG 20. Aortic valve stenosis. 320-MDCT. Eighty-six-year-old female with severe aortic stenosis. The double oblique transverse multiplanar reconstruction shows a tricuspid aortic valve with thickened valve leaflets and extensive calcifications. LA, left atrium. 290
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FIG 21. Mitral annulus calcification. 320-MDCT. Parasagittal multiplanar reconstruction showing the mitral annulus of an 86-year-old female with moderate mitral regurgitation. Severe calcification of the mitral annulus (arrows) spreading toward the left ventricular outflow tract can be observed. LVOT, left ventricular outflow tract; MA, mitral annulus.
FIG 22. Aortic dissection. 320-MDCT. Axial image of a 29-year-old male with history of hypertension presenting with acute epigastric pain. Ungated CT shows an aortic dissection Stanford classification type A involving the ascending aorta. The presence of a type A aortic dissection is an urgent surgical indication to prevent extension back to the pericardium and prevent aortic rupture. Note the dissection flap separating both contrast columns in the ascending aorta (arrow) and in the descending aorta (arrowhead). In the dissection, the media are separated from the adventitia for a variable length along the aorta, where most dissections have a tear in the intima, allowing blood to advance and fill the false lumen. Stanford type B aorta dissections begin beyond the arch vessels and have better outcome with medical treatment.18 F, false channel. Curr Probl Cardiol, June 2009
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FIG 23. Aortic coarctation with bicuspid aortic valve. 64-MDCT. Multiplanar reconstructions of a 17-year-old male patient with bicuspid aortic valve (A) and severe aortic valve regurgitation combined with stenosis causing ascending aorta dilatation (asterisk, B). In addition, a dilated left ventricle and left ventricular hypertrophy can be observed (B). CT revealed severe aortic coarctation with pinpoint stenosis (arrow) at the classic location just distal from the origin of the left subclavian artery (B). Note the dilated intercostal arteries entering the descending aorta just distal from the coarctation supplying collateral blood (arrowheads C), and the extremely dilated mammarian artery (C) also serving as collateral circulation route to the lower half of the body. Notably, the patient only had mild symptoms. Aortic coarctation is associated with congenital bicuspid aortic valve in 25-50% of patients.18
FIG 24. Thoracic aneurysm. 320-MDCT. Axial image of a 77-year-old female with ascending aorta aneurysm referred for CT to determine the extent preoperatively for sizing the replacing graft. Aneurysm (A) diameter was 5.7 ⫻ 6.3 cm in this axial plane. Thoracic aortic aneurysms are the result of dilatation involving all layers of the aortic wall and are commonly associated with atherosclerotic disease. The normal ascending aorta diameter should be less than 4 cm; over 5 cm indicates the presence of an aneurysm. The risk for rupture is strongly dependent on size,18 with over 30% 5-year risk for aneurysms of 6 cm or more. Operative repair is usually indicated if the aneurysm exceeds 6 cm in diameter. Ao, aorta; PA, pulmonary artery; LA, left atrium. 292
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FIG 25. Massive pulmonary embolism with right ventricular dilatation. 16-MDCT. Axial images in a 52-year-old male patient with massive acute pulmonary embolism with ⬎ 50% of the pulmonary arteries obstructed. Central pulmonary embolus (arrow, A) and extensive obstruction of the left and right pulmonary arteries by emboli (arrows, B) can be observed. The pulmonary artery obstruction resulted in acute right ventricular dilatation (C). Note that the overloaded dysfunctional right ventricle causes interventricular septum shift toward the left ventricle with left ventricular compression. These changes with septum shift cause decreased preload and distensibility of the left ventricle due to pericardial constraint, resulting in decreased cardiac output and possibly hypotensive shock.19 RV, right ventricle.
FIG 26. Pulmonary vein stenosis. Three-dimensional volume-rendered reconstruction of the left atrium and pulmonary veins. Occlusion of the left superior pulmonary vein (LSPV) can be observed (black arrow), while also stenosis of the left inferior pulmonary vein (LIPV) is visible (white arrow). No abnormalities were observed in the right superior and inferior pulmonary veins (RSPV and RIPV, respectively). The most common cause of pulmonary vein stenosis in adult patients is radiofrequency ablation procedures around the pulmonary veins for the treatment of atrial fibrillation.21 Pulmonary vein stenosis is frequently difficult to recognize clinically but can be easily identified using noninvasive imaging techniques such as CT.21 LA, left atrium; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; RIPV, right inferior pulmonary vein; RSVP, right superior pulmonary vein. Curr Probl Cardiol, June 2009
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Coronary Anatomy With the introduction of electron-beam computed tomography and, more recently, multi-detector row CT, noninvasive visualization of the coronary arteries with high resolution has become possible. Initially coronary artery disease could be identified by non-contrast-enhanced Jeroen J. Bax has research grants from Medtronic (Tolochenaz, Switzerland), Boston Scientific (Maastricht, the Netherlands), BMS medical imaging (N. Billerica, MA), St. Jude Medical (Veenendaal, the Netherlands), Biotronik (Berlin, Germany), GE Healthcare (St Giles, UK), and Edwards Lifesciences (Saint-Prex, Switzerland). All images in this article were obtained by helical 16-MDCT or 64-MDCT (Toshiba Aquilion 16CFX or Aquilion 64 CT scanner, Toshiba Medical System, Otawara, Japan) or by volumetric 320-MDCT (Toshiba, Aquilion one, Tochigi-ken, Japan). Curr Probl Cardiol 2009;34:277-295. 0146-2806/$ – see front matter doi:10.1016/j.cpcardiol.2009.01.004
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FIG 1. Coronary calcium. 320-MDCT. Noncontrast axial image showing extensive calcifications (arrowheads) in the left main and left anterior descending coronary artery in an asymptomatic 75-year-old patient with hypercholesterolemia and hypertension.
FIG 2. Normal coronary angiogram. 320-MDCT. Curved multiplanar reconstructions of the left anterior descending (A), left circumflex (B), and right coronary artery (C), respectively, of a 72-year-old female with atypical chest pain and an elevated risk profile (hypertension, hypercholesterolemia, and family history of coronary artery disease). CT angiography showed only minor wall irregularities and absence of significant stenosis.
coronary calcium scoring. Extensive data are available supporting the prognostic value of the presence and extent of calcifications in predicting future cardiovascular events.1 More recently, direct coronary angiography has also become possible. High accuracies have been demonstrated in the detection of significant coronary stenoses as compared to invasive coronary angiography.2 The technique appears to be particularly valuable in 278
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FIG 3. Significant coronary stenosis. 320-MDCT. Curved multiplanar reconstruction of the left anterior descending coronary artery of a 56-year-old female, revealing a nonsignificant calcified plaque (arrowhead) in the proximal part of the artery, whereas a significant stenosis can be observed more distally (arrow).
the exclusion of significant coronary artery disease. In addition, the technique allows accurate assessment of coronary anomalies and fistula by providing detailed information on both their origin and their course3,4 (Figs 1-6).
Coronary Stents, Bypass Grafts, and Veins The assessment of patients with previous stents may be more difficult with CT as the metallic content can give rise to artifacts. At present, therefore, only assessment of patients with relatively larger stents (⬎ 3.0-mm-diameter) can be recommended.5 In contrast, for the assessment of coronary bypass grafts, the three-dimensional nature of Curr Probl Cardiol, June 2009
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FIG 4. Benign coronary artery anomaly. 64-MDCT. Seventy-one-year-old male referred for CT angiography for suspected coronary anomaly of the left coronary artery. (A) On the maximum intensity oblique coronal multiplanar reconstruction the origin of the left coronary artery from the right coronary cusp (separately from the right coronary artery) can be observed. (B) Axial image showing the anomalous retro-aortic course of the left coronary artery (arrow) running between the aorta and left atrium to the anterior ventricular wall. (C, D, and E) Curved multiplanar reconstructions in different orientations further illustrate the origin and course of the coronary anomaly. This anomaly with retro-aortic course is considered benign. Ao, aorta; LA, left atrium; LCA, left coronary artery; LV, left ventricle; RCA, right coronary artery.
FIG 5. Malignant coronary artery anomaly. 64-MDCT. Three-dimensional volume-rendered reconstruction (A) showing an anomalous right coronary artery (arrow) arising from the left coronary cusp and coursing between the aorta (#) and pulmonary trunk (*). On the consecutive axial images (B, C), the interarterial course between the aorta and pulmonary trunk with reduction of the lumen at the origin is further illustrated. These anomalous interarterial arteries often arise with an acute angle and are somewhat narrowed in the proximal part. This anomaly is considered malignant because the interarterial course can result in compression (pinching off) of the coronary artery and reduction of blood flow, particularly during exercise. Patients are at risk for exercise-induced ischemia, infarction, and sudden death. 280
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FIG 6. Coronary artery fistula. 320-MDCT. Axial images of a 67-year-old female with large coronary artery fistula (arrows, A-D) from the right coronary artery to the coronary sinus with retrosternal course and course through the right and left atrio-ventricular groove. Note that the size of the fistula (arrows, A) is even larger than the size of the aortic root (A). Over 90% of fistulas drain into the low-pressure right-sided venous circulation causing a left-to-right shunt. Bypassing the myocardial capillary bed causes reduction in myocardial blood flow distal to the site of the anomalous connection. Therefore, the myocardium beyond the fistula’s origin is at risk for ischemia, most evident during exercise.22 This patient had atrioventricular valve regurgitation additional to the large fistula and showed signs of congestive cardiac failure; note the bilateral pleural effusion (A-D) and dilated hepatic veins (D).
CT offers clear advantages.6 Finally, visualization of the cardiac venous anatomy with CT may be useful in the evaluation of patients before cardiac resynchronization therapy and may predict procedural success of transvenous left ventricular lead implantation7,8 (Figs 7-10).
Cardiac Anatomy and Structure CT with intravenous contrast allows high-resolution imaging of cardiac anatomy and structures. Retrospectively, the images can be viewed in all planes (including the established cardiac planes), facilitating accurate assessment of atrial and ventricular dimensions. Also, CT is frequently Curr Probl Cardiol, June 2009
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FIG 7. Coronary stents. 64-MDCT. Curved multiplanar reconstructions of the left anterior descending coronary artery of two patients with previous stent implantation following anterior myocardial infarction. In (A) two patent bare metal stents (partially overlapping) with a diameter of 3.5 mm can be observed, while in (B) a patent drug-eluting stent (diameter 3.5 mm) is present. Note that also the presence of distal runoff can be observed, although this should not be used as the only criterion for stent patency.23 While CT angiography allows accurate ruling out of in-stent restenosis in larger stents (diameter ⬎ 3.0 mm), obtaining an accurate diagnosis remains challenging in smaller stents.
FIG 8. Coronary bypass graft stenosis. 64-MDCT. Coronal (A) and three-dimensional volumerendered (B) CT images showing severe graft disease in a 68-year-old male. Occlusion of the venous graft to the right coronary artery (arrowheads) was identified, while the venous graft to the left circumflex coronary artery (white arrow) was also shown to be proximally occluded. Note the severely diseased native right coronary artery (B, black arrows). Invasive coronary angiography for coronary bypass grafts is frequently technically more difficult than for native vessels with longer procedure times. In contrast, individual bypass grafts can be located more easily with CT. However, severe calcifications and extensive atherosclerotic disease of the native coronary arteries, frequently observed in this patient population, can impair evaluation of the native coronary segments. Ao, aorta; LV, left ventricle.
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FIG 9. Cardiac venous anatomy. 64-MDCT. Three-dimensional volume-rendered reconstructions, showing a posterior (A), lateral (B), and anterior (C) view of the heart. In addition to the coronary arteries, the cardiac venous system is clearly visible. In (A), the coronary sinus (CS) and its first and second tributaries can be observed. The first tributary is the posterior interventricular vein (PIV), which runs in the posterior interventricular groove. The second tributary is the posterior vein of the left ventricle (PVLV). The great cardiac vein (GCV) continues in the atrioventricular groove (B). Only a small left marginal vein (LMV) can be observed (arrow). Finally, the GCV continues in the anterior interventricular groove as the anterior interventricular vein (AIV, C). Noninvasive visualization of cardiac venous anatomy may be of value in candidates for cardiac resynchronization therapy.7 AIV, anterior interventricular vein; CS, coronary sinus; GCV, great cardiac vein; LMV, left marginal vein; PIV, posterior interventricular vein; PVLV, posterior vein of the left ventricle.
FIG 10. Thebesian valve. 320-MDCT. Axial (A) and coronal (B) images of a 77-year-old female patient showing the location of the Thebesian valve (arrowheads) of the coronary sinus. Note the difference in contrast indicated by the arrowheads, indicating the location of the valve. The presence of a Thebesian valve, which is a remnant of the embryonic right valve and occurs with variable formation at the origin of the coronary sinus, may obstruct or complicate cannulation of the coronary sinus ostium and can thus be the cause of an unsuccessful transvenous approach for left ventricular lead implantation.8
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FIG 11. Left atrial appendage filling defect representing pseudothrombus. 320-MDCT. Axial image of a 59-year-old male, pre-radiofrequency ablation therapy for treatment of atrial fibrillation. A filling defect can be observed in the tip of the left atrial appendage (LAA), suspected for intracardiac thrombus (arrow). However, echocardiographic evaluation excluded thrombus. The filling defect is explained by blood stasis due to poor contractile function of the left atrial appendage in patients with atrial fibrillation, which seldom occurs in patients without atrial fibrillation.10,24 Nevertheless, true atrial or atrial appendage thrombus is also highly associated with atrial fibrillation.24 Ao, aorta; LAA, left atrial appendage; RVOT, right ventricular outflow tract.
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FIG 13. Healed myocardial infarction with calcified apex aneurysm and fatty replacement. 64-MDCT. Short-axis (A) and axial (B) images of a 66-year-old man with history of a 15-year-old anterior myocardial infarction. A dilated left ventricle with myocardial thinning in the anterior and septal regions with subendocardial low-attenuation nonenhancing rim with attenuation value of ⫺70 HU can be observed. In addition, dense calcifications, indicating old calcified myocardial infarction at the midventricular and apical level, are present. The dark rim consists of fat deposition that occurs as an age-related process in this old myocardial infarction. Small foci of intramyocardial fat can be observed in healthy persons as well as in the left ventricular myocardium (more often in females than males) and in the right ventricular myocardium (increasing with age) that typically involves the endocardial aspect of the myocardium. Fatty replacement of myocardial tissue is more often observed in patients with infarction more than 3 years old.25
used in the case of suspected intracardiac shunts such as those caused by interatrial and interventricular defects.9 In addition, the technique can be helpful in the identification of intracardiac masses, such as thrombi and tumors. However, filling defects at early-phase CT suggesting thrombus should be confirmed by delayed-phase CT, echocardiography, or magnetic resonance imaging. Frequently, the appearance could also be due to blood stasis caused by poor contractile function rather than true thrombus formation10 (Figs 11-17).
Fig. 12. Apical thrombus in dilating cardiomyopathy. 64-MDCT. Axial images of a 43-year-old male with known dilating cardiomyopathy. Note the severely dilated left ventricle (LV, A) and the filling defect in the LV apex (arrow, B) due to apical thrombus. LV thrombi are located mainly at the apex and only occur with an abnormally contracting left ventricular wall. Thrombi occur in aneurysms, in the area adjacent to healed myocardial infarction, and with idiopathic dilated cardiomyopathy with poor wall motion. Thrombus is the most frequent intracardiac mass and its major risk is systemic embolization.
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FIG 14. Lipomatous hypertrophy of the interatrial septum. 64-MDCT. Axial images of a 76-year-old male with lipomatous atrium septum. Thick low-attenuating interatrial septum consisting of excessive deposition of fatty tissue where the fossa ovalis is spared (arrow, A), usually causing a “dumbbell” appearance. (B) Lower level. Lipomatous hypertrophy of the interatrial septum exceeding 1 cm thickness is present in about 3% of patients. It is a benign disorder that has been associated with pulmonary emphysema and may cause arrhythmias.26
FIG 15. Ventricular diverticulum and small atrium septum defect. 64-MDCT. Axial images in a 59-year-old female, showing incidental finding of a small diverticulum (arrow, A) at the base of the left ventricle near the right ventricular insertion point and was associated with an atrium septum defect (arrow, B), where a small left-to-right shunt is visible as little contrast leak from the left atrium (LA) to the right atrium (RA). Diverticula are not very frequent with an incidence found at autopsy of about 0.4% in patients who died of cardiac disease. On CT, diverticula have been found with an incidence of 2.2%, where most are observed along the inferior or inferoseptal regions of the left ventricle, primarily at the site of right ventricular insertion.27 The majority are completely closed at systole. However, when located at the interventricular septum, contrast outpouchings may rather be remains of a closed muscular ventricular septum defect. There is some debate whether all described diverticula---with higher incidence found on CT than at pathology---are true diverticula (outbulgings of hollow organs) or rather crypts. Crypts penetrating into the muscular wall located mainly at the mid and basal inferoseptal segments have been described to be present in most hypertrophic cardiomyopathy mutation carriers and may precede development of left ventricular hypertrophy.28 LA, left atrium; RA, right atrium.
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FIG 16. Left atrium diverticulum. 64-MDCT. Axial image of a 53-year-old man showing a small smooth-walled atrium diverticulum located at the typical location of the atrial roof directly posterior to the aortic root near the venoatrial junction of the right superior pulmonary vein (arrow). This is a common finding present in about 16-30% of the population.29,30 It has been speculated that such diverticulum may represent an incompletely regressed remnant of a cardinal vein during embryologic development.29 Possibly, atrium diverticula may be clinically relevant due to potentially decreased efficacy of ablation therapy if the diverticulum causes a gap in the line of block, or theoretical risk of thrombus.29
Pericardial Abnormalities The pericardium can be recognized on CT as a thin low-attenuation structure that lies between the epicardial and pericardial fat. Although echocardiography and chest radiography are used for the initial evaluation of pericardial disease, CT offers the advantage of high-resolution images with lower operator dependence as compared to echocardiography.11 The excellent delineation of the pericardium can facilitate diagnosis of constrictive pericarditis.11 Other pericardial diseases, such as pericardial effusion and pericardial cysts, can be easily recognized on CT as well12 (Figs 18 and 19). Curr Probl Cardiol, June 2009
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FIG 17. Cardiac tumor. 16-MDCT. Left ventricle (LV) short-axis multiplanar reformation of a 48-year-old male patient who was HIV⫹, showing extensive right ventricular (RV) thickening (*) due to a massively infiltrating tumor that also extended into the right atrium. Also, note the nodular thickening of the pericardium (arrows). Pathology investigation of biopsies taken from the right ventricle and right atrium were diagnostic for B-cell non-Hodgkin lymphoma. Metastases or direct extension of malignant extracardiac tumors have a 40-fold higher frequency than primary tumors. Non-Hodgkin’s lymphoma is present in about 3% of patients with AIDS, where secondary cardiac involvement is not uncommon but is often undetected due to nonspecific symptoms.31 LV, left ventricle; RV, right ventricle.
Cardiac Valves Although echocardiography remains the primary technique for evaluation of valvular heart disease, emerging data show the feasibility of CT to study aortic and mitral valve anatomy.13-15 Particularly in the setting of percutaneous valve repair or replacement, the detailed information on valve morphology, dimensions, and surrounding structures obtained by CT may be highly relevant and help in avoiding complications during the procedure.16,17 By using multiphase data sets, the leaflet or cusp motion can be evaluated in cine-loops, providing even some crude information on valvular function13-15 (Figs 20 and 21).
Thorax and Large Vessels Although in the past, invasive angiography served as the gold standard for the evaluation of aortic aneurysms and dissections, the 288
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FIG 18. Calcified constrictive pericarditis. 64-MDCT. Axial images of a 58-year-old male with thickened calcified pericardium (arrowheads) causing constrictive pericarditis (A-D). Note the extensive calcifications and calcified lump compressing the anterior right ventricle wall (D, arrow). While calcified thickened pericarditis is suggestive for tuberculous etiology,32 other well-known causes are postmediastinal irradiation injury and post open-heart surgery. In the Western world, however, idiopathic constrictive pericarditis is most common.32 Constrictive pericarditis can cause distortion of the ventricles with narrow, compressed appearance of both ventricles and dilated right atrium and caval veins.33 All signs were present in this patient at chest CT. Patient had signs of heart failure with pleural effusion and dilated caval veins.
use of CT angiography is currently preferred. The technique allows accurate evaluation of aneurysm size as well as classification of dissection type, which has important prognostic and therapeutic implications.18 CT is also the first-choice technique in evaluating patients with suspected pulmonary emboli, allowing simultaneous evaluation of right ventricular morphology.19 Finally, CT angiography can be useful in identifying variants in pulmonary vein anatomy before radiofrequency catheter ablation for atrial fibrillation.20 Following this procedure, the technique may identify complications such as pulmonary vein stenosis21 (Figs 22-26). Curr Probl Cardiol, June 2009
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FIG 19. Pericardial cyst. 64-MDCT. Axial image of a 41-year-old male showing a large homogenous 12.5 ⫻ 4.3 ⫻ 10.0 cm mass (*) with low-attenuation values at the right heart border, with smooth contour, without visible wall, and without enhancement. Characteristics are consistent with cyst with the location in the anterior cardiophrenic angle typical for pericardial cyst.12
FIG 20. Aortic valve stenosis. 320-MDCT. Eighty-six-year-old female with severe aortic stenosis. The double oblique transverse multiplanar reconstruction shows a tricuspid aortic valve with thickened valve leaflets and extensive calcifications. LA, left atrium. 290
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FIG 21. Mitral annulus calcification. 320-MDCT. Parasagittal multiplanar reconstruction showing the mitral annulus of an 86-year-old female with moderate mitral regurgitation. Severe calcification of the mitral annulus (arrows) spreading toward the left ventricular outflow tract can be observed. LVOT, left ventricular outflow tract; MA, mitral annulus.
FIG 22. Aortic dissection. 320-MDCT. Axial image of a 29-year-old male with history of hypertension presenting with acute epigastric pain. Ungated CT shows an aortic dissection Stanford classification type A involving the ascending aorta. The presence of a type A aortic dissection is an urgent surgical indication to prevent extension back to the pericardium and prevent aortic rupture. Note the dissection flap separating both contrast columns in the ascending aorta (arrow) and in the descending aorta (arrowhead). In the dissection, the media are separated from the adventitia for a variable length along the aorta, where most dissections have a tear in the intima, allowing blood to advance and fill the false lumen. Stanford type B aorta dissections begin beyond the arch vessels and have better outcome with medical treatment.18 F, false channel. Curr Probl Cardiol, June 2009
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FIG 23. Aortic coarctation with bicuspid aortic valve. 64-MDCT. Multiplanar reconstructions of a 17-year-old male patient with bicuspid aortic valve (A) and severe aortic valve regurgitation combined with stenosis causing ascending aorta dilatation (asterisk, B). In addition, a dilated left ventricle and left ventricular hypertrophy can be observed (B). CT revealed severe aortic coarctation with pinpoint stenosis (arrow) at the classic location just distal from the origin of the left subclavian artery (B). Note the dilated intercostal arteries entering the descending aorta just distal from the coarctation supplying collateral blood (arrowheads C), and the extremely dilated mammarian artery (C) also serving as collateral circulation route to the lower half of the body. Notably, the patient only had mild symptoms. Aortic coarctation is associated with congenital bicuspid aortic valve in 25-50% of patients.18
FIG 24. Thoracic aneurysm. 320-MDCT. Axial image of a 77-year-old female with ascending aorta aneurysm referred for CT to determine the extent preoperatively for sizing the replacing graft. Aneurysm (A) diameter was 5.7 ⫻ 6.3 cm in this axial plane. Thoracic aortic aneurysms are the result of dilatation involving all layers of the aortic wall and are commonly associated with atherosclerotic disease. The normal ascending aorta diameter should be less than 4 cm; over 5 cm indicates the presence of an aneurysm. The risk for rupture is strongly dependent on size,18 with over 30% 5-year risk for aneurysms of 6 cm or more. Operative repair is usually indicated if the aneurysm exceeds 6 cm in diameter. Ao, aorta; PA, pulmonary artery; LA, left atrium. 292
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FIG 25. Massive pulmonary embolism with right ventricular dilatation. 16-MDCT. Axial images in a 52-year-old male patient with massive acute pulmonary embolism with ⬎ 50% of the pulmonary arteries obstructed. Central pulmonary embolus (arrow, A) and extensive obstruction of the left and right pulmonary arteries by emboli (arrows, B) can be observed. The pulmonary artery obstruction resulted in acute right ventricular dilatation (C). Note that the overloaded dysfunctional right ventricle causes interventricular septum shift toward the left ventricle with left ventricular compression. These changes with septum shift cause decreased preload and distensibility of the left ventricle due to pericardial constraint, resulting in decreased cardiac output and possibly hypotensive shock.19 RV, right ventricle.
FIG 26. Pulmonary vein stenosis. Three-dimensional volume-rendered reconstruction of the left atrium and pulmonary veins. Occlusion of the left superior pulmonary vein (LSPV) can be observed (black arrow), while also stenosis of the left inferior pulmonary vein (LIPV) is visible (white arrow). No abnormalities were observed in the right superior and inferior pulmonary veins (RSPV and RIPV, respectively). The most common cause of pulmonary vein stenosis in adult patients is radiofrequency ablation procedures around the pulmonary veins for the treatment of atrial fibrillation.21 Pulmonary vein stenosis is frequently difficult to recognize clinically but can be easily identified using noninvasive imaging techniques such as CT.21 LA, left atrium; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; RIPV, right inferior pulmonary vein; RSVP, right superior pulmonary vein. Curr Probl Cardiol, June 2009
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