PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of springeropenLink to Publisher's site
The International Journal of Cardiovascular Imaging
 
Int J Cardiovasc Imaging. 2010 March; 26(3): 355–358.
Published online 2009 December 24. doi:  10.1007/s10554-009-9559-6
PMCID: PMC2846328

CT perfusion angiography; beware of artifacts!

Over the past years, myocardial perfusion imaging has been established as the reference standard for prognosis and clinical decision making of patients with coronary artery disease (CAD). Myocardial perfusion has predominantly been assessed by single photon emission tomography (SPECT) [17] and, more recently, by positron emission tomography (PET) and magnetic resonance imaging (MRI) [816].

Amongst the advanced cardiac imaging modalities, multi detector computed tomography (CT) angiography has emerged as a reliable non-invasive method for the assessment of coronary anatomy, CAD, and cardiac function [1722]. Multiple studies involving over several thousands of patients have established that CT angiography is highly accurate for delineation of the presence and severity of coronary atherosclerosis [2330]. CT angiography may also reveal the total plaque burden, i.e. both calcified and non-calcified components, for individual patients with coronary atherosclerosis [3140].

The advent of prospectively gated acquisition techniques for 64-slice CT angiography has allowed a significant reduction in dose exposure. Consequently, a combined approach of CT coronary angiography and myocardial perfusion imaging with CT angiography might potentially become feasible at a total radiation dose of less than 10 mSv, particularly for the assessment of patients with established CAD, who are likely to have diffuse calcification [4047].

Since myocardial perfusion by CT angiography is based on myocardial signal density, it is crucial to determine the normal values of myocardial signal density and to identify potential mechanisms of misinterpretation of perfusion defects. In routine CT angiography acquisitions, there might be a considerable signal density drop at the posterobasal wall resembling perfusion defects possibly being attributed to beam hardening artifacts.

In the current issue of the International Journal of Cardiovascular Imaging Rodríguez-Granillo et al. [48] investigated normal myocardial signal density levels during CT angiography and evaluated the impact of artifacts due to beam hardening. A group of 36 consecutive asymptomatic patients with a low probability of CAD were referred for CT angiography because of inconclusive or discordant functional tests. Perfusion defects were defined as a myocardial segment having a signal density two standard deviations below the average myocardial signal density for the 16 left ventricular American Heart Association (AHA) segments. Signal density was evaluated in 576 American Heart Association (AHA) segments and 36 posterobasal segments. The mean myocardial signal density at the posterobasal segment was 53.5 ± 35.1 Hounsfield Units, whereas the mean myocardial signal density at the basal, mid and apical myocardium was 97.4 ± 17.3 Hounsfield Units, with significant differences between posterobasal and all AHA segments. Posterobasal perfusion defects were identified in 26 (72%) patients. The only variable associated to the presence of posterobasal perfusion defect was heart rate, whereas body mass index, blood signal density of the left and right ventricles, contrast-to-noise ratio, and the extent of atherosclerosis were not related to the presence of perfusion defects. The main findings of the study were that (1) beam hardening artifacts are a common finding at CT angiography of asymptomatic patients affecting predominantly the posterobasal wall, (2) perfusion defects at the short axis plane including the mitral valve and the left ventricular outflow tract are not related to technical issues whereas heart rate may be associated with this finding, (3) perfusion defects can be also identified at the inferior and anteroapical segments but this occurs less often.

Occurrence of attenuation artifacts during radionuclide SPECT perfusion imaging has been considered an important limitation of the technique [4951]. Apical thinning due to the overlying diaphragm and the occurrence of anteroseptal defects as a result of breast attenuation are very common causes for unwanted perfusion deficits, leading to image misinterpretation and potentially a wrong diagnosis. The present study [48] indicates that perfusion artifacts also occur at CT perfusion angiography and could therefore be a reason for misinterpretation. These perfusion defects can largely be ascribed to beam hardening artifacts most likely from the spine for posterobasal segments and from the sternum for anteroapical segments.

In radionuclide myocardial perfusion SPECT imaging, successful attenuation correction programs have been developed in order to discriminate between true and false perfusion defects [5255]. Similarly, correction algorithms are currently being designed for CT angiography with the same purpose. Recently, So et al. [56] designed phantoms to simulate the beam hardening artifacts encountered in cardiac CT perfusion studies of humans and animals. These phantoms were used to investigate whether beam hardening artifacts could be reduced with this approach and to determine the optimal settings of the correction algorithm for patient and animal studies, which depend upon the anatomy of the scanned subject. The correction algorithm was also applied to correct beam hardening in a clinical study to further demonstrate the effectiveness of this technique.

To summarize, the study by Rodríguez-Granillo et al. [48] convincingly shows that in an asymptomatic population with no history of CAD, who undergo CT perfusion angiography, artifacts in the posterobasal wall are a common finding in more than two-thirds of patients. This phenomenon of pseudo-perfusion defects may considerably affect proper image interpretation and should be taken into account in the judgment of CT perfusion images. In the near future, correction algorithms for CT perfusion angiography will assist in identifying the true nature of the defects in order to establish the correct diagnosis.

Open Access

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Footnotes

Editorial comment on the article of Rodríguez-Granillo et al. (doi: 10.1007/s10554-009-9531-5).

References

1. Bavelaar-Croon CD, Pauwels EK, Wall EE. Gated single-photon emission computed tomographic myocardial imaging: a new tool in clinical cardiology. Am Heart J. 2001;141:383–390. doi: 10.1067/mhj.2001.112780. [PubMed] [Cross Ref]
2. Wall EE, Heidendal GA, Hollander W, Westera G, Roos JP. I-123 labeled hexadecenoic acid in comparison with thallium-201 for myocardial imaging in coronary heart disease. A preliminary study. Eur J Nucl Med. 1980;5:401–405. doi: 10.1007/BF00261781. [PubMed] [Cross Ref]
3. Bax JJ, Lamb H, Dibbets P, Pelikan H, et al. Comparison of gated single-photon emission computed tomography with magnetic resonance imaging for evaluation of left ventricular function in ischemic cardiomyopathy. Am J Cardiol. 2000;86:1299–1305. doi: 10.1016/S0002-9149(00)01231-5. [PubMed] [Cross Ref]
4. Chamuleau SA, Eck-Smit BL, Meuwissen M, et al. Long-term prognostic value of CFVR and FFR versus perfusion scintigraphy in patients with multivessel disease. Neth Heart J. 2007;15:369–374. [PMC free article] [PubMed]
5. Bavelaar-Croon CD, Kayser HW, Wall EE, et al. Left ventricular function: correlation of quantitative gated SPECT and MR imaging over a wide range of values. Radiology. 2000;217:572–575. [PubMed]
6. Wall EE, Hollander W, Heidendal GA, Westera G, Majid PA, Roos JP. Dynamic myocardial scintigraphy with 123I-labeled free fatty acids in patients with myocardial infarction. Eur J Nucl Med. 1981;6:383–389. [PubMed]
7. Kurvers MJ, Braam RL, Verzijlbergen JF, Heestermans AA, Ten Berg JM. Myocardial salvage in STEMI patients treated with primary coronary angioplasty as demonstrated by myocardial SPECT. Neth Heart J. 2007;15:422–423. [PMC free article] [PubMed]
8. Wall EE, Dijkman PR, Roos A, et al. Diagnostic significance of gadolinium-DTPA (diethylene-triamine penta-acetic acid) enhanced magnetic resonance imaging in thrombolytic treatment for acute myocardial infarction: its potential in assessing reperfusion. Br Heart J. 1990;63:12–17. doi: 10.1136/hrt.63.1.12. [PMC free article] [PubMed] [Cross Ref]
9. Dijkman PR, Wall EE, Roos A, et al. Acute, subacute, and chronic myocardial infarction: quantitative analysis of gadolinium-enhanced MR images. Radiology. 1991;180:147–151. [PubMed]
10. Roos A, Matheijssen NA, Doornbos J, Dijkman PR, Voorthuisen AE, Wall EE. Myocardial infarct size after reperfusion therapy: assessment with Gd-DTPA-enhanced MR imaging. Radiology. 1990;176:517–521. [PubMed]
11. Wal RM, Werkum JW, Cocq d’Armandville MC, et al. Giant aneurysm of an aortocoronary venous bypass graft compressing the right ventricle. Neth Heart J. 2007;15:252–254. [PMC free article] [PubMed]
12. Niezen RA, Helbing WA, Wall EE, Geest RJ, Rebergen SA, Roos A. Biventricular systolic function and mass studied with MR imaging in children with pulmonary regurgitation after repair for tetralogy of Fallot. Radiology. 1996;201:135–140. [PubMed]
13. Pluim BM, Lamb HJ, Kayser HW, et al. Functional and metabolic evaluation of the athlete’s heart by magnetic resonance imaging and dobutamine stress magnetic resonance spectroscopy. Circulation. 1998;97:666–672. [PubMed]
14. Vliegen HW, Doornbos J, Roos A, Jukema JW, Bekedam MA, Wall EE. Value of fast gradient echo magnetic resonance angiography as an adjunct to coronary arteriography in detecting and confirming the course of clinically significant coronary artery anomalies. Am J Cardiol. 1997;79:773–776. doi: 10.1016/S0002-9149(96)00866-1. [PubMed] [Cross Ref]
15. Hoogendoorn LI, Pattynama PM, Buis B, Geest RJ, Wall EE, Roos A. Noninvasive evaluation of aortocoronary bypass grafts with magnetic resonance flow mapping. Am J Cardiol. 1995;75:845–848. doi: 10.1016/S0002-9149(99)80429-9. [PubMed] [Cross Ref]
16. Holman ER, Buller VG, Roos A, et al. Detection and quantification of dysfunctional myocardium by magnetic resonance imaging. A new three-dimensional method for quantitative wall-thickening analysis. Circulation. 1997;95:924–931. [PubMed]
17. Schuijf JD, Bax JJ, Wall EE. Anatomical and functional imaging techniques: basically similar or fundamentally different? Neth Heart J. 2007;15:43–44. [PMC free article] [PubMed]
18. Werkhoven JM, Schuijf JD, Jukema JW, et al. Anatomic correlates of a normal perfusion scan using 64-slice computed tomographic coronary angiography. Am J Cardiol. 2008;101:40–45. doi: 10.1016/j.amjcard.2007.07.046. [PubMed] [Cross Ref]
19. Scholte AJ, Bax JJ, Wackers FJ. Screening of asymptomatic patients with type 2 diabetes mellitus for silent coronary artery disease: combined use of stress myocardial perfusion imaging and coronary calcium scoring. J Nucl Cardiol. 2006;13:11–18. doi: 10.1016/j.nuclcard.2005.11.002. [PubMed] [Cross Ref]
20. Wijpkema JS, Dorgelo J, Willems TP, et al. Discordance between anatomical and functional coronary stenosis severity. Neth Heart J. 2007;15:5–11. [PMC free article] [PubMed]
21. Molhoek SG, Bax JJ, Bleeker GB, et al. Comparison of response to cardiac resynchronization therapy in patients with sinus rhythm versus chronic atrial fibrillation. Am J Cardiol. 2004;94:1506–1509. doi: 10.1016/j.amjcard.2004.08.028. [PubMed] [Cross Ref]
22. Thygesen K, Alpert JS, White HD. Universal definition of myocardial infarction; Joint ESC/ACCF/AHA/WHF Task Force for the Redefinition of Myocardial Infarction. Eur Heart J. 2007;28:2525–2538. doi: 10.1093/eurheartj/ehm355. [PubMed] [Cross Ref]
23. Lennep JE, Westerveld HT, Lennep HW, Zwinderman AH, Erkelens DW, Wall EE. Apolipoprotein concentrations during treatment and recurrent coronary artery disease events. Arterioscler Thromb Vasc Biol. 2000;20:2408–2413. [PubMed]
24. Chamuleau SA, Vrijsen KR, Rokosh DG, Tang XL, Piek JJ, Bolli R. Cell therapy for ischaemic heart disease: focus on the role of resident cardiac stem cells. Neth Heart J. 2009;17:199–207. [PMC free article] [PubMed]
25. Leeuw JG, Wardeh A, Sramek A, Wall EE. Pseudo-aortic dissection after primary PCI. Neth Heart J. 2007;15:265–266. [PMC free article] [PubMed]
26. Braun S, Wall EE, Emanuelsson S, Kobrin I. Effects of a new calcium antagonist, mibefradil (Ro 40–5967), on silent ischemia in patients with stable chronic angina pectoris: a multicenter placebo-controlled study. The mibefradil international study group. J Am Coll Cardiol. 1996;27:317–322. doi: 10.1016/0735-1097(95)00472-6. [PubMed] [Cross Ref]
27. Portegies MC, Schmitt R, Kraaij CJ, et al. Lack of negative inotropic effects of the new calcium antagonist Ro 40–5967 in patients with stable angina pectoris. J Cardiovasc Pharmacol. 1991;18:746–751. doi: 10.1097/00005344-199111000-00013. [PubMed] [Cross Ref]
28. ten Kate GJ, Wuestink AC, Feyter PJ. Coronary artery anomalies detected by MSCT-angiography in the adult. Neth Heart J. 2008;16:369–375. [PMC free article] [PubMed]
29. Schuijf JD, Jukema JW, Wall EE, Bax JJ. Multi-slice computed tomography in the evaluation of patients with acute chest pain. Acute Card Care. 2007;9:214–221. doi: 10.1080/17482940701589275. [PubMed] [Cross Ref]
30. Groen JM, Greuter MJ, Vliegenthart R, et al. Calcium scoring using 64-slice MDCT, dual source CT and EBT: a comparative phantom study. Int J Cardiovasc Imaging. 2008;24:547–556. doi: 10.1007/s10554-007-9282-0. [PMC free article] [PubMed] [Cross Ref]
31. Bakx AL, Wall EE, Braun S, Emanuelsson H, Bruschke AV, Kobrin I. Effects of the new calcium antagonist mibefradil (Ro 40–5967) on exercise duration in patients with chronic stable angina pectoris: a multicenter, placebo-controlled study. Ro 40–5967 International Study Group. Am Heart J. 1995;130:748–757. doi: 10.1016/0002-8703(95)90073-X. [PubMed] [Cross Ref]
32. Schuijf JD, Pundziute G, Jukema JW, et al. Diagnostic accuracy of 64-slice multislice computed tomography in the noninvasive evaluation of significant coronary artery disease. Am J Cardiol. 2006;98:145–148. doi: 10.1016/j.amjcard.2006.01.092. [PubMed] [Cross Ref]
33. Jongbloed MR, Lamb HJ, Bax JJ, et al. Noninvasive visualization of the cardiac venous system using multislice computed tomography. J Am Coll Cardiol. 2005;45:749–753. doi: 10.1016/j.jacc.2004.11.035. [PubMed] [Cross Ref]
34. Schuijf JD, Wijns W, Jukema JW, et al. Relationship between noninvasive coronary angiography with multi-slice computed tomography and myocardial perfusion imaging. J Am Coll Cardiol. 2006;48:2508–2514. doi: 10.1016/j.jacc.2006.05.080. [PubMed] [Cross Ref]
35. Pundziute G, Schuijf JD, Jukema JW, et al. Prognostic value of multislice computed tomography coronary angiography in patients with known or suspected coronary artery disease. J Am Coll Cardiol. 2007;49:62–70. doi: 10.1016/j.jacc.2006.07.070. [PubMed] [Cross Ref]
36. Henneman MM, Schuijf JD, Pundziute G, et al. Noninvasive evaluation with multislice computed tomography in suspected acute coronary syndrome: plaque morphology on multislice computed tomography versus coronary calcium score. J Am Coll Cardiol. 2008;52:216–222. doi: 10.1016/j.jacc.2008.04.012. [PubMed] [Cross Ref]
37. Nooijer R, Verkleij CJ, der Thüsen JH, et al. Lesional overexpression of matrix metalloproteinase-9 promotes intraplaque hemorrhage in advanced lesions but not at earlier stages of atherogenesis. Arterioscler Thromb Vasc Biol. 2006;26:340–346. doi: 10.1161/01.ATV.0000197795.56960.64. [PubMed] [Cross Ref]
38. Laarse A, Kerkhof PL, Vermeer F, et al. Relation between infarct size and left ventricular performance assessed in patients with first acute myocardial infarction randomized to intracoronary thrombolytic therapy or to conventional treatment. Am J Cardiol. 1988;61:1–7. doi: 10.1016/0002-9149(88)91294-5. [PubMed] [Cross Ref]
39. Hoeven BL, Pires NM, Warda HM, et al. Drug-eluting stents: results, promises and problems. Int J Cardiol. 2005;99:9–17. doi: 10.1016/j.ijcard.2004.01.021. [PubMed] [Cross Ref]
40. Ertaş G, Beusekom HM, Giessen WJ. Late stent thrombosis, endothelialisation and drug-eluting stents. Neth Heart J. 2009;17:177–180. [PMC free article] [PubMed]
41. Scholte AJ, Schuijf JD, Kharagjitsingh AV, et al. Different manifestations of coronary artery disease by stress SPECT myocardial perfusion imaging, coronary calcium scoring, and multislice CT coronary angiography in asymptomatic patients with type 2 diabetes mellitus. J Nucl Cardiol. 2008;15:503–509. doi: 10.1016/j.nuclcard.2008.02.015. [PubMed] [Cross Ref]
42. Juwana YB, Wirianta J, Suryapranata H, Boer MJ. Left main coronary artery stenosis undetected by 64-slice computed tomography: a word of caution. Neth Heart J. 2007;15:255–256. [PMC free article] [PubMed]
43. Scholte AJ, Schuijf JD, Kharagjitsingh AV, et al. Prevalence of coronary artery disease and plaque morphology assessed by multi-slice computed tomography coronary angiography and calcium scoring in asymptomatic patients with type 2 diabetes. Heart. 2008;94:290–295. doi: 10.1136/hrt.2007.121921. [PubMed] [Cross Ref]
44. Akram K, Voros S. Absolute coronary artery calcium scores are superior to MESA percentile rank in predicting obstructive coronary artery disease. Int J Cardiovasc Imaging. 2008;24:743–749. doi: 10.1007/s10554-008-9305-5. [PubMed] [Cross Ref]
45. Tops LF, Bax JJ, Zeppenfeld K, et al. Fusion of multislice computed tomography imaging with three-dimensional electroanatomic mapping to guide radiofrequency catheter ablation procedures. Heart Rhythm. 2005;2:1076–1081. doi: 10.1016/j.hrthm.2005.07.019. [PubMed] [Cross Ref]
46. Sirineni GK, Raggi P, Shaw LJ, Stillman AE. Calculation of coronary age using calcium scores in multiple ethnicities. Int J Cardiovasc Imaging. 2008;24:107–111. doi: 10.1007/s10554-007-9233-9. [PubMed] [Cross Ref]
47. Marques KM, Westerhof N. Characteristics of the flow velocity-pressure gradient relation in the assessment of stenoses: an in vitro study. Neth Heart J. 2008;16:156–162. [PMC free article] [PubMed]
48. Rodríguez-Granillo GA, Rosales MA, Degrossi E, Rodriguez AE (2009) Signal density of left ventricular myocardial segments and impact of beam hardening artifact: implications for myocardial perfusion assessment by multidetector CT coronary angiography. Int J Cardiovasc Imaging. [Epub ahead of print] [PubMed]
49. Morita K, Tsukamoto E, Tamaki N. Perfusion-BMIPP mismatch: specific finding or artifact? Int J Cardiovasc Imaging. 2002;18:279–282. doi: 10.1023/A:1017416220561. [PubMed] [Cross Ref]
50. America YG, Bax JJ, Dibbets-Schneider P, Pauwels EK, Wall EE. Evaluation of the Quantitative Gated SPECT (QGS) software program in the presence of large perfusion defects. Int J Cardiovasc Imaging. 2005;21:519–529. doi: 10.1007/s10554-005-0274-7. [PubMed] [Cross Ref]
51. Purser NJ, Armstrong IS, Williams HA, Tonge CM, Lawson RS. Apical thinning: real or artefact? Nucl Med Commun. 2008;29:382–389. doi: 10.1097/MNM.0b013e3282f4a22e. [PubMed] [Cross Ref]
52. Stinis CT, Lizotte PE, Movahed MR. Impaired myocardial SPECT imaging secondary to silicon- and saline-containing breast implants. Int J Cardiovasc Imaging. 2006;22:449–455. doi: 10.1007/s10554-005-9068-1. [PubMed] [Cross Ref]
53. Verburg FA, Romijn RL, Nekolla S, Verzijlbergen JF. A phantom assessment of cold stomach-related artifacts in myocardial perfusion imaging. Nucl Med Commun. 2009;30:569–573. doi: 10.1097/MNM.0b013e32832c79ce. [PubMed] [Cross Ref]
54. Kovalski G, Keidar Z, Frenkel A, Israel O, Azhari H. Correction for respiration artefacts in myocardial perfusion SPECT is more effective when reconstructions supporting collimator detector response compensation are applied. J Nucl Cardiol. 2009;16:949–955. doi: 10.1007/s12350-009-9148-z. [PubMed] [Cross Ref]
55. Ali I, Ruddy TD, Almgrahi A, Anstett FG, Wells RG. Half-time SPECT myocardial perfusion imaging with attenuation correction. J Nucl Med. 2009;50:554–562. doi: 10.2967/jnumed.108.058362. [PubMed] [Cross Ref]
56. So A, Hsieh J, Li JY, Lee TY. Beam hardening correction in CT myocardial perfusion measurement. Phys Med Biol. 2009;21:3031–3050. doi: 10.1088/0031-9155/54/10/005. [PubMed] [Cross Ref]

Articles from Springer Open Choice are provided here courtesy of Springer