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|Year : 2010 | Volume
| Issue : 2 | Page : 125-130
Cardiac imaging: Current and emerging applications
B Jankharia1, A Raut2
1 Piramal Diagnostic Services (Formerly Wellspring), Piramal Diagnostics - Jankharia Imaging, Bhaveshwar Vihar, India
2 Department of Radiology, KEM Hospital, Parel, Mumbai, India
|Date of Submission||13-Jan-2009|
|Date of Decision||12-Mar-2009|
|Date of Acceptance||20-Feb-2010|
|Date of Web Publication||8-Jul-2010|
Piramal Diagnostic Services (Formerly Wellspring), Piramal Diagnostics - Jankharia Imaging, Bhaveshwar Vihar
Source of Support: None, Conflict of Interest: None
Cardiac magnetic resonance imaging (MRI) and computed tomography (CT) scan have made big inroads as modalities used for evaluation of various pathologies of the heart. Cardiac MRI is typically used for perfusion and viability studies as well as to study various cardiomyopathies, valvular diseases and the pericardium. It has been used in the evaluation of congenital heart diseases over the last two decades. Cardiac CT is used mainly for the evaluation of the coronary arteries, typically in the setting of "to rule out coronary artery disease".
Keywords: Cardiac computed tomography, cardiac magnetic resonance imaging, computed tomography, congenital heart disease, coronary artery disease, magnetic resonance imaging, review, viability
|How to cite this article:|
Jankharia B, Raut A. Cardiac imaging: Current and emerging applications. J Postgrad Med 2010;56:125-30
Cardiac magnetic resonance imaging (CMR) and cardiac CT (CCT) are the new kids on the block as far as cardiac imaging is concerned. This review describes the indications for these two modalities.
| :: Cardiac MRI|| |
A 1.5T scanner is required with high-speed gradients and specialized scanning sequences.
Image acquisition is done in a particular phase of cardiac cycle to avoid image blur and cardiac motion artifacts. This is called as electrocardiographic gating.
Pulse sequences used for CMR can be broadly divided into dark-blood and bright-blood techniques. A motion picture loop throughout the various phases of cardiac cycle can be produced with gradient echo (GRE) and balanced steady-state sequences to get rapid cine imaging. Cine imaging is useful in the functional assessment of ventricles.
Congenital heart disease
CMR is useful in understanding complex anatomy in Congenital heart disease (CHD) and gives information not obtained by echocardiography.  It is especially useful in evaluating the functional significance in various types of CHDs, e.g. in evaluating right heart function in Ebtein's anomaly.  CMR not only detects intraventricular shunts such as atrial and ventricular septal defects, but can also calculate shunt size with phase-velocity mapping.  CMR plays an important role in evaluating complex surgical shunts and baffles and has a very important role to play in the postoperative evaluation of patients with tetralogy of Fallot. 
Valvular heart disease
CMR can demonstrate the presence and quantify the severity of valvular heart disease.  Using phase-velocity mapping as well as ventricular chamber volumes, aortic stenosis and regurgitation as well as mitral disease can be accurately evaluated. The valve areas can be accurately measured using planimetry. 
Arrhythmogenic right ventricular dysplasia (ARVD) [Figure 1] is characterized by fatty or fibrous infiltration of the right ventricle (RV) walls with thinning and pseudo-sacculations.  The presence of fat can be identified on T1W images. The cine images show thinning of the anterior and inferior walls, enlargement and dilatation of the RV, areas of dyskinesia or focal bulging, reduced ejection fraction and impaired ventricular filling during diastole. 
The diagnosis is usually made on echocardiography. CMR is better than echocardiography for diagnosing apical hypertrophic cardiomyopathy.  CMR also helps in assessing the functional sub-valvular narrowing in patients with hypertrophic obstructive cardiomyopathy.  The presence of abnormal areas of enhancement suggests necrosis and fibrosis and may indicate an adverse prognosis. 
Inflammatory and infiltrative cardiomyopathy
CMR is an excellent tool for diagnosing myocardial inflammation as in viral myocarditis  or sarcoidosis.  Abnormal areas of mid-myocardial and epicardial enhancement are seen often with wall motion abnormality. Infiltrative conditions like Fabry's disease  and amyloidosis  can also be diagnosed reliably.
In patients with thalassemia, iron deposition in the myocardium is a significant cause of death.  Using the T2* parameter, the myocardial iron content can be quantified and then followed up regularly to see efficacy of chelating agents. 
CMR is more accurate than 2D echocardiography in the functional assessment of the heart.  CMR can measure ventricular ejection fraction and end-diastolic and end-systolic volumes.
Coronary artery imaging
Despite reports in the literature, , CMR is still not a robust modality for the evaluation of the coronary arteries. 
Myocardial perfusion and viability
Perfusion: First pass perfusion studies can be performed using intravenous gadolinium and stress with either adenosine or dipyridamole.  The technique is sensitive for diagnosing areas of hypoperfusion, corresponding to the presence of ischemia. 
Myocardial viability [Figure 2]
Using special sequences, delayed hyperenhancement can be studied with CMR. It has been shown that all infarcts  show delayed hyperenhancement, 5-10 min after the injection of intravenous gadolinium. The extent of infarction correlates with the ability to recover function after revascularization  and thus this study can help decide whether revascularization will be of help in patients with myocardial infarction.
Cardiac and pericardial masses and thrombi
CMR is an accurate means to evaluate cardiac and pericardial masses.  Gadolinium enhancement differentiates thrombus from neoplasm. 
CMR is an accurate tool for diagnosing pericardial effusion and constrictive pericarditis.  Pericardial thickening of more than 4 mm in a patient with a restrictive physiology is usually diagnostic.  The presence of paradoxical septal deviation in early diastole in the first expiratory breath on real-time CMR has been shown to be a useful sign to diagnose constriction. 
| :: Cardiac CT|| |
At the bare minimum, a 64-slice CT scanner is required for accurate CT angiography (CTA).  Faster, 256- and 320-slice  and dual-source  CT scanners are now available as well.
Irrespective of the speed of the scanner, the best images are obtained with a lower heart rate  and thus beta-blockers are routinely used to bring down the heart rate to around 65 beats per min or less. Intravenous contrast is used at a high injection speed to opacity the coronary arteries. A calcium score study is often performed prior to the intravenous injection and in some centers if the score is more than 800, a CTA is then not performed. Cardiac CT is contraindicated in those patients with severe allergy to iodinated contrast or in those suspected to be pregnant.
Coronary artery imaging
Cardiac CT has a negative predictive value of around 97-99% , in the evaluation of coronary artery disease [Figure 3]. The positive predictive value varies from 44-93%, depending on the patient selection criteria.  In view of this, the main indication of cardiac CT is still in the setting of "to rule out coronary artery disease", i.e. to screen for coronary artery pathology in the setting of medium to high-risk but asymptomatic patients or in patients with atypical symptoms. 
Post-bypass [Figure 4]
Cardiac CT is an excellent tool to study bypass grafts and to assess their patency  and is currently used as the first tool in the evaluation of patients suspected to have graft pathology.
The results in patients with stents to diagnose in-stent pathology are quite variable  due to difficulties in in-stent lumen visualization, and cardiac CT is typically used mainly in patients with larger stents and to look at disease elsewhere in the coronary tree. Catheter angiography remains the gold standard for in-stent lumen visualization.
Coronary artery anomalies
Cardiac CT is the gold standard in the evaluation of coronary artery anomalies. 
Cardiac CT reconstruction in multiple phases allows the assessment of ejection fraction and end-diastolic and end-systolic volumes with considerable accuracy. 
Cardiac CT has been found useful in the evaluation of aortic and mitral valve areas and the extent of calcification.  The evaluation of valve areas may help in decision-making as far as management is concerned.
Pericardium and cardiac and pericardial masses
Cardiac CT is useful in diagnosing pericardial thickening, calcification, effusion and masses  as well as cardiac masses. 
Congenital heart disease
The role of cardiac CT in CHD is mainly to evaluate the pulmonary arteries, veins and aorta.  It is especially useful in patients with pulmonary atresia to evaluate the presence and extent of major aorto-pulmonary collaterals  [Figure 5]. It also helps in the evaluation of Glenn and Fontan shunts  and in other postoperative situations.
| :: Conclusion|| |
Both cardiac CT and CMR have become extremely useful tools to study various facets of the heart as described above. They both have different strengths. Cardiac CT is best suited to study the coronary tree. CMR is best used to evaluate the myocardium, pericardium and the valves.
| :: References|| |
|1.||Gutierrez FR, Ho ML, Siegel MJ. Practical applications of magnetic resonance in congenital heart disease. Magn Reson Imaging Clin N Am 2008;16:403-35. |
|2.||Cantinotti M, Bell A, Razavi R. Role of magnetic resonance imaging in different ways of presentation of Ebstein's anomaly. J Cardiovasc Med (Hagerstown) 2008;9:628-30. |
|3.||Piaw CS, Kiam OT, Rapaee A, Khoon LC, Bang LH, Ling CW, et al. Use of non-invasive phase contrast magnetic resonance imaging for estimation of atrial septal defect size and morphology: A comparison with transesophageal echo. Cardiovasc Intervent Radiol 2006;29:230-4. |
|4.||Norton KI, Tong C, Glass RB, Nielsen JC. Cardiac MR imaging assessment following tetralogy of fallot repair. Radiographics 2006;26:197-211. |
|5.||Masci PG, Dymarkowski S, Bogaert J. Valvular heart disease: What does cardiovascular MRI add? Eur Radiol 2008;18:197-208. |
|6.||Pouleur AC, le Polain de Waroux JB, Pasquet A, Vancraeynest D, Vanoverschelde JL, Gerber BL. Planimetric and continuity equation assessment of aortic valve area: Head to head comparison between cardiac magnetic resonance and echocardiography. J Magn Reson Imaging 2007;26:1436-43. |
|7.||Boxt LM, Rozenshtein A. MR imaging of arrhythmogenic right ventricular dysplasia. Magn Reson Imaging Clin N Am 2003;11:163-71. |
|8.||Tandri H, Macedo R, Calkins H, Marcus F, Cannom D, Scheinman M, et al. Role of magnetic resonance imaging in arrhythmogenic right ventricular dysplasia: Insights from the North American arrhythmogenic right ventricular dysplasia (ARVD/C) study. Am Heart J 2008;155:147-53. |
|9.||Sakamoto T. Apical hypertrophic cardiomyopathy (apical hypertrophy): An overview. J Cardiol 2001;37:161-78. |
|10.||Hansen MW, Merchant N. MRI of hypertrophic cardiomyopathy: Part I, MRI appearances. AJR Am J Roentgenol 2007;189:1335-43. |
|11.||Hansen MW, Merchant N. MRI of hypertrophic cardiomyopathy: Part 2, Differential diagnosis, risk stratification, and posttreatment MRI appearances. AJR Am J Roentgenol 2007;189:1344-52. |
|12.||Abdel-Aty H, Boy P, Zagrosek A, Wassmuth R, Kumar A, Messroghli D, et al. Diagnostic performance of cardiovascular magnetic resonance in patients with suspected acute myocarditis: Comparison of different approaches. J Am Coll Cardiol 2005;45:1815-22. |
|13.||Smedema JP, Snoep G, van Kroonenburgh MP, van Geuns RJ, Dassen WR, Gorgels AP, et al. Evaluation of the accuracy of gadolinium-enhanced cardiovascular magnetic resonance in the diagnosis of cardiac sarcoidosis. J Am Coll Cardiol 2005;45:1683-90. |
|14.||Moon JC, Sachdev B, Elkington AG, McKenna WJ, Mehta A, Pennell DJ, et al. Gadolinium enhanced cardiovascular magnetic resonance in Anderson-Fabry disease. Evidence for a disease specific abnormality of the myocardial interstitium. Eur Heart J 2003;24:2151-5. |
|15.||Maceira AM, Joshi J, Prasad SK, Moon JC, Perugini E, Harding I, et al. Cardiovascular magnetic resonance in cardiac amyloidosis. Circulation 2005;111:186-93. |
|16.||Pennell DJ. T2* magnetic resonance and myocardial iron in thalassemia. Ann N Y Acad Sci 2005;1054:373-8. |
|17.||Tanner MA, Galanello R, Dessi C, Smith GC, Westwood MA, Agus A, et al. A randomized, placebo-controlled, double-blind trial of the effect of combined therapy with deferoxamine and deferiprone on myocardial iron in thalassemia major using cardiovascular magnetic resonance. Circulation 2007;115:1876-84. |
|18.||Epstein FH. MRI of left ventricular function. J Nucl Cardiol 2007;14:729-44. |
|19.||Kim WY, Danias PG, Stuber M, Flamm SD, Plein S, Nagel E, et al. Coronary magnetic resonance angiography for the detection of coronary stenoses. N Engl J Med 2001;345:1863-9. |
|20.||Sakuma H, Ichikawa Y, Chino S, Hirano T, Makino K, Takeda K. Detection of coronary artery stenosis with whole-heart coronary magnetic resonance angiography. J Am Coll Cardiol 2006;48:1946-50. |
|21.||Maintz D, Ozgun M, Hoffmeier A, Quante M, Fischbach R, Manning WJ, et al. Whole-heart coronary magnetic resonance angiography: Value for the detection of coronary artery stenoses in comparison to multislice computed tomography angiography. Acta Radiol 2007;48:967-73. |
|22.||Pennell DJ. Cardiovascular magnetic resonance and the role of adenosine pharmacologic stress. Am J Cardiol 2004;94:26D-31D. |
|23.||Plein S, Radjenovic A, Ridgway JP, Barmby D, Greenwood JP, Ball SG, et al. Coronary artery disease: Myocardial perfusion MR imaging with sensitivity encoding versus conventional angiography. Radiology 2005;235:423-30. |
|24.||Kim RJ, Wu E, Rafael A, Chen EL, Parker MA, Simonetti O, et al. The use of contrast-enhanced magnetic resonance imaging to identify reversible myocardial dysfunction. N Engl J Med 2000;343:1445-53. |
|25.||Kwong RY, Korlakunta H. Diagnostic and prognostic value of cardiac magnetic resonance imaging in assessing myocardial viability. Top Magn Reson Imaging 2008;19:15-24. |
|26.||Syed IS, Feng D, Harris SR, Martinez MW, Misselt AJ, Breen JF, et al. MR imaging of cardiac masses. Magn Reson Imaging Clin N Am 2008;16:137-64. |
|27.||Srichai MB, Junor C, Rodriguez LL, Stillman AE, Grimm RA, Lieber ML, et al. Clinical, imaging, and pathological characteristics of left ventricular thrombus: A comparison of contrast-enhanced magnetic resonance imaging, transthoracic echocardiography, and transesophageal echocardiography with surgical or pathological validation. Am Heart J 2006;152:75-84. |
|28.||Misselt AJ, Harris SR, Glockner J, Feng D, Syed IS, Araoz PA. MR imaging of the pericardium. Magn Reson Imaging Clin N Am 2008;16:185-99. |
|29.||Wang ZJ, Reddy GP, Gotway MB, Yeh BM, Hetts SW, Higgins CB. CT and MR imaging of pericardial disease. Radiographics 2003;23:S167-80. |
|30.||Francone M, Dymarkowski S, Kalantzi M, Rademakers FE, Bogaert J. Assessment of ventricular coupling with real-time cine MRI and its value to differentiate constrictive pericarditis from restrictive cardiomyopathy. Eur Radiol 2006;16:944-51. |
|31.||Pugliese F, Mollet NR, Runza G, van Mieghem C, Meijboom WB, Malagutti P, et al. Diagnostic accuracy of non-invasive 64-slice CT coronary angiography in patients with stable angina pectoris. Eur Radiol 2006;16:575-82. |
|32.||Rybicki FJ, Otero HJ, Steigner ML, Vorobiof G, Nallamshetty L, Mitsouras D, et al. Initial evaluation of coronary images from 320-detector row computed tomography. Int J Cardiovasc Imaging 2008;24:535-46. |
|33.||Miller JC, Abbara S, Mamuya WS, Thrall JH, Uppot RN. Dual-source CT for cardiac imaging. J Am Coll Radiol 2009;6:65-8. |
|34.||Leschka S, Scheffel H, Husmann L, Gamperli O, Marincek B, Kaufmann PA, et al. Effect of decrease in heart rate variability on the diagnostic accuracy of 64-MDCT coronary angiography. AJR Am J Roentgenol 2008;190:1583-90. |
|35.||Budoff MJ, Dowe D, Jollis JG, Gitter M, Sutherland J, Halamert E, et al. Diagnostic performance of 64-multidetector row coronary computed tomographic angiography for evaluation of coronary artery stenosis in individuals without known coronary artery disease: Results from the prospective multicenter ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial. J Am Coll Cardiol 2008;52:1724-32. |
|36.||Min JK, Shaw LJ, Devereux RB, Okin PM, Weinsaft JW, Russo DJ, et al. Prognostic value of multidetector coronary computed tomographic angiography for prediction of all-cause mortality. J Am Coll Cardiol 2007;50:1161-70. |
|37.||Mowatt G, Cook JA, Hillis GS, Walker S, Fraser C, Jia X, Waugh N. 64-Slice computed tomography angiography in the diagnosis and assessment of coronary artery disease: systematic review and meta-analysis. Heart 2008;94:1386-93. |
|38.||Marano R, Liguori C, Rinaldi P, Storto ML, Politi MA, Savino G, et al. Coronary artery bypass grafts and MDCT imaging: What to know and what to look for. Eur Radiol 2007;17:3166-78. |
|39.||Oncel D, Oncel G, Karaca M. Coronary stent patency and in-stent restenosis: Determination with 64 section multidetector CT coronary angiography-initial experience. Radiology 2007;242:403-9. |
|40.||Kim SY, Seo JB, Do KH, Heo JN, Lee JS, Song JW, et al. Coronary artery anomalies: Classification and ECG-gated multi-detector row CT findings with angiographic correlation. Radiographics 2006;26:317-33 |
|41.||Orakzai SH, Orakzai RH, Nasir K, Budoff MJ. Assessment of cardiac function using multidetector row computed tomography. J Comput Assist Tomogr 2006;30:555-63. |
|42.||Vogel-Claussen J, Pannu H, Spevak PJ, Fishman EK, Bluemke DA. Cardiac valve assessment with MR imaging and 64-section multi-detector row CT. Radiographics 2006;26:1769-84. |
|43.||Lopez Costa I, Bhalla S. Computed tomography and magnetic resonance imaging of the pericardium. Semin Roentgenol 2008;43:234-45. |
|44.||Tatli S, Lipton MJ. CT for intracardiac thrombi and tumors. Int J Cardiovasc Imaging 2005;21:115-31. |
|45.||Lee T, Tsai IC, Fu YC, Jan SL, Wang CC, Chang Y, et al. Using multidetector-row CT in neonates with complex congenital heart disease to replace diagnostic cardiac catheterization for anatomical investigation: Initial experiences in technical and clinical feasibility. Pediatr Radiol 2006;36:1273-82. |
|46.||Hayabuchi Y, Inoue M, Watanabe N, Sakata M, Nabo MM, Kitagawa T, et al. Assessment of systemic-pulmonary collateral arteries in children with cyanotic congenital heart disease using multidetector-row computed tomography: Comparison with conventional angiography. Int J Cardiol 2010;138:266-71. |
|47.||Leschka S, Oechslin E, Husmann L, Desbiolles L, Marincek B, Genoni M, et al. Pre- and postoperative evaluation of congenital heart disease in children and adults with 64-section CT. Radiographics 2007;27:829-46. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
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