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Myocardial Perfusion SPECT

  • Author: Ricardo Cardona, MD; Chief Editor: Gowthaman Gunabushanam, MD, FRCR  more...
 
Updated: Feb 24, 2016
 

Background

Single-photon emission computed tomography (SPECT) is a nuclear medicine topographic imaging technique that uses gamma rays. It is similar to conventional nuclear medicine planar imaging using gamma cameras; however, the computer in SPECT provides 3-dimensional (3D) images. Note the summary figure and other images below.

Device summary. To acquire single-photon emission Device summary. To acquire single-photon emission computed tomography (SPECT) images, the patient lies still in a supine position, and the gamma camera is rotated around the patient. Courtesy of Patrick J. Lynch, Yale University.
Single-photon emission computed tomography (SPECT) Single-photon emission computed tomography (SPECT) images compared with illustrations of the heart from similar views. The SPECT images (bottom row) show the distribution of the tracer and therefore the relative blood flow to the different regions of the myocardium. The top rows are illustrations of the heart to compare with the SPECT images from similar views. Notice there are more enhancements in the area that corresponds to the left ventricle because of its greater thickness. Courtesy of Patrick J. Lynch, Yale University.
Planar imaging. The gamma camera detects the gamma Planar imaging. The gamma camera detects the gamma rays emitted from the tracer, and the image of where the tracer is found in the organs is transmitted to the computer. In planar technique, the computer provides a 2-dimensional myocardial perfusion image. Courtesy of Patrick J. Lynch, Yale University.

SPECT is based upon the flow-dependent and/or metabolism-dependent selective uptake of a radioactive tracer by functional myocardial tissue. This method was developed to evaluate myocardial perfusion and viability and is applied both at rest and after exercise or pharmacologic stress to assess inducible ischemia due to flow limiting coronary stenoses.

The history of cardiac nuclear medicine dates back to 1973, which marked the introduction of the exercise stress-test myocardial scan by H. William Strauss[1] and the first application of thallium-201 myocardial perfusion imaging by Elliot Lebowitz. Since then, it has been increasingly used in clinical cardiology. Technical developments that have fuelled this increase are single-photon emission tomographic (SPET) imaging, pharmacological stress, and electrocardiogram (ECG)-gated imaging.

The underlying principle is that under conditions of stress, the diseased myocardium receives less blood flow than normal myocardium. SPECT imaging performed after stress reveals the distribution of the radiopharmaceutical, and therefore the relative blood flow to the different regions of the myocardium. Comparing stress images to a further set of images obtained at rest aids in diagnosis. See the following image.

SPECT imaging performed after stress. The upper ro SPECT imaging performed after stress. The upper row shows short-axis slices after pharmacologic stress; the lower row shows the same slices when the body is at rest in conventional cardiac SPECT with Tc-99m tetrofosmin as a radiotracer. Arrows indicate a small perfusion defect on the backside of the heart (visible only on the stress images), showing ischemia in this region of the heart wall. Courtesy of Philipp A Kaufmann, MD, and Oliver Gämperli, MD, University Hospital Zurich.

The technique involves the intravenous injection of small amounts of radioactive tracer (gamma-emitting radioisotope), which is avidly taken up by the cardiomyocytes so that the initial myocardial tracer distribution is in proportion to the viable myocardium.

Images taken during dynamic exercise or pharmacologically induced stress (using vasodilators such as adenosine or beta-agonist such as dobutamine) and rest injections enable independent assessment of myocardial perfusion and viability.

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Indications

In patients who present with acute, stable chest pain, SPECT has been shown to be more cost-effective than any other diagnostic modality to date[2] and more accurate than exercise ECG in detecting myocardial ischemia. Special indications include determination of the hemodynamic significance of anomalous coronary arteries[3] and muscle bridging[4] and coronary aneurisms in the setting of Kawasaki disease.[5]

Inferior and posterior abnormalities and small areas of infarction can be identified, as well as the occluded blood vessels and the mass of infarcted and viable myocardium.

In patients with known CAD, SPECT has been proven the single more powerful technique in predicting the likelihood of future cardiac events.[6]

Assessment of viable myocardium in a specific coronary artery distribution after a heart attack: Stress images in SPECT may help determine the degree of inducible ischemia or viable myocardium that are amenable to revascularization.[7, 8]

Post intervention revascularization (coronary artery bypass graft or angioplasty) evaluation[9]

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Contraindications

Absolute contraindications to dynamic exercise include the following:

  • In patients with non-ST-segment elevation acute coronary syndrome or unstable angina, once stabilized, exercise stress can be considered 24-72 hours after chest pain, depending on clinically assessed risk. [10] ST-segment elevation myocardial infarction (MI) within the previous 4 days. [11]
  • Left main coronary artery stenosis that is likely to be hemodynamically significant; left ventricular failure with symptoms at rest; recent history of life-threatening arrhythmias; severe dynamic or fixed left ventricular outflow tract obstruction (aortic stenosis and obstructive hypertrophic cardiomyopathy); severe systemic hypertension (systolic blood pressure 220 mm Hg and/or diastolic blood pressure >120 mm Hg); recent pulmonary embolism or infarction, thrombophlebitis, or active deep vein thrombosis; and active endocarditis, myocarditis, or pericarditis are absolute contraindications. [12]

Relative contraindications to dynamic exercise include the following:

  • Left bundle branch block (LBBB), bifascicular block, and ventricular paced rhythms (because dynamic exercise leads to perfusion abnormalities of the septum and adjacent walls in the absence of obstructive coronary disease) [13]
  • Inability or poor motivation to perform dynamic exercise
  • Recent exercise ECG that failed to achieve an acceptable workload (≥85% of the maximum predicted heart rate)

Absolute contraindications to vasodilator stress include the following:

  • Recent acute coronary syndrome is a contraindication. Once stabilized, stress with vasodilators can be considered 24-72 hours after chest pain, depending on clinically assessed risk. [10]
  • Suspected or known severe bronchospasm, second-degree and third-degree atrioventricular block in the absence of a functioning pacemaker, sick sinus syndrome in the absence of a functioning pacemaker, hypotension (systolic blood pressure < 90 mm Hg), and xanthine intake in the last 12 hours, or dipyridamole use in the last 24 hours are contraindications. [14]

Relative contraindications to vasodilator stress include the following:

  • Bradycardia of less than 40 beats/min: Initial dynamic exercises normally increases the rate sufficiently to start the infusion. [14]
  • Recent cerebral ischemia or infarction

Absolute contraindications to dobutamine stress include the following:

  • Same as for dynamic exercise
  • Known hypokalemia [15]

Relative contraindications to dobutamine stress include LBBB, bifascicular block, and paced rhythm, for the same reason as for dynamic exercise.

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Technical Considerations

Radiation exposure

Myocardial perfusion imaging has the highest average effective dose (15.6 mSv) and the highest percentage (22.1%) of all effective doses compared with other major radiologic procedures, including CT studies.[16] Low-dose ionizing radiation has been linked with up to 2% of solid cancers and leukemia. A small but cumulative danger from radiation due to SPECT is noted. However, new radioactive tracers such as rubidium-82 reduce the radiation dose to the patient by a factor of 10 compared to technetium-99m. In the future, a complete myocardial perfusion examination may be achievable while maintaining a patient’s dose less than 3 mSv.[17, 18]

According to a study by Einstein et al, compared with standard Anger SPECT (A-SPECT) cameras, new high-efficiency (HE) cameras with specialized collimators and solid-state cadmium-zinc-telluride detectors offer the potential to maintain image quality while reducing the radiation dose. They found that ultra-low-dose high-efficiency SPECT (ULD HE SPECT) rest imaging correlates highly with standard-low-dose (SLD) A-SPECT. ULD HE SPECT was shown to have improved image quality, to have comparable extracardiac activity, and to achieve radiation dose reduction to 1 mSv for a single injection.[19]

In a Netherlands study of 24 patients who underwent clinically indicated myocardial perfusion imaging with cadmium zinc telluride (CZT) SPECT and a body weight-dependent (3 MBq/kg) technetium-99m-tetrofosmiin tracer dose, differences in segmental uptake values, ejection fraction, and end-diastolic volume were greater for shorter scans than for the 8-minute reference scan. Six minutes was the shortest acquisition time in stress MPI that did not affect the diagnostic value for a tracer dose of 3 MBq/kg.[20]  On average, the diagnostic value was influenced in 7.7 segments per patient using the 2-minute scans, in comparison to 2.0 and 0.8 segments per patient using the 4- and 6-minute scans, respectively. In addition, the 4-min scans led to a significantly reduced image quality compared with the 8-min scans (P < 0.05). This was not the case for the 6-min scan.[20]

The use of a hybrid CZT SPECT/64-slice CT system for dose reduction was studied to determine maximal degree of dose reduction without compromising image quality and quantification precision of clinical MPS. Ultra-low dose (<190 MBq) myocardial perfusion imaging, even with short imaging times (<6 min), was found to be feasible using a hybrid CZT SPECT/CT camera without compromising image quality or significantly altering quantification of myocardial perfusion or LV function.[21]

According to the authors, an additional 50% reduction of current low-dose recommendations from American Society of Nuclear Cardiology (ASNC) guidelines for 99mTc-labeled myocardial perfusion imaging is highly feasible while retaining short imaging protocols. For patients of normal MPS, there were no differences in defect size (DS), LV volumes, and ejection fraction (EF), regardless of 50% or 75% dose reduction. For patients of abnormal MPS, at 50% dose reduction, there was a significant difference in global DS but not in regional DS in the left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) regions. At 75% dose reduction, however, the difference was statistically significant in all areas, including global DS. Nonetheless, differences in the DS were minimal. The LV end-diastolic and end-systolic volumes and LVEF were not significantly different, regardless of 50% or 75% DR.[21]

Allergic potential to radiocontrast

Contrary to the risk of radiocontrast-induced allergy seen in CT angiography and coronary angiography, SPECT has a small risk of dye allergy. This is because in SPECT the radioisotopes used are in nanomole quantities and the vehicle used is normal saline. No known adverse reactions to the chemical molecules are recognized (sestamibi or tetrofosmin).

Other considerations

The presence of a healthcare professional that is up-to-date with in basic life support is required for the duration of all stress procedures. Personnel trained in advance life support should be rapidly available. Emergency equipment, drugs, and support personnel should also be available.

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Outcomes

The incidence of fatal myocardial infarction/cardiac death in patients undergoing stress for myocardial perfusion imaging for exercise, dobutamine,[22, 23] dipyridamole,[24] or adenosine[25] is 0.01, 0.0, 0.05 and 0.0%, respectively.[25] The incidence of nonfatal myocardial infarction/major cardiac complication in patients undergoing stress for myocardial perfusion imaging for exercise, dobutamine, dipyridamole, or adenosine is 0.02, 0.3, 0.05 and 0.1%, respectively.[22, 23, 24, 26, 25]

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Contributor Information and Disclosures
Author

Ricardo Cardona, MD Attending Physician, Department of Internal Medicine, Beth Israel Deaconess Hospital

Disclosure: Nothing to disclose.

Chief Editor

Gowthaman Gunabushanam, MD, FRCR Assistant Professor, Department of Diagnostic Radiology, Yale University School of Medicine

Gowthaman Gunabushanam, MD, FRCR is a member of the following medical societies: American Roentgen Ray Society, Connecticut State Medical Society

Disclosure: Nothing to disclose.

Acknowledgements

Acknowledgments

The author wishes to thank Dr. Alexander Rubin for his guidance in creating this article.

References
  1. Zaret BL, Strauss HW, Martin ND, Wells HP Jr, Flamm MD Jr. Noninvasive regional myocardial perfusion with radioactive potassium. Study of patients at rest, with exercise and during angina pectoris. N Engl J Med. 1973 Apr 19. 288(16):809-12. [Medline].

  2. Loong CY, Anagnostopoulos C. Diagnosis of coronary artery disease by radionuclide myocardial perfusion imaging. Heart. 2004 Aug. 90 Suppl 5:v2-9. [Medline]. [Full Text].

  3. Donaldson RM, Raphael M, Radley-Smith R, Yacoub MH, Ross DN. Angiographic identification of primary coronary anomalies causing impaired myocardial perfusion. Cathet Cardiovasc Diagn. 1983. 9(3):237-49. [Medline].

  4. Lee YS, Moon DH, Shin JW, Park SW, Park SJ, Lee HK. Dipyridamole TI-201 SPECT imaging in patients with myocardial bridging. Clin Nucl Med. 1999 Oct. 24(10):759-64. [Medline].

  5. Fukuda T, Akagi T, Ishibashi M, Inoue O, Sugimura T, Kato H. Noninvasive evaluation of myocardial ischemia in Kawasaki disease: comparison between dipyridamole stress thallium imaging and exercise stress testing. Am Heart J. 1998 Mar. 135(3):482-7. [Medline].

  6. Hachamovitch R, Berman DS, Kiat H, et al. Exercise myocardial perfusion SPECT in patients without known coronary artery disease: incremental prognostic value and use in risk stratification. Circulation. 1996 Mar 1. 93(5):905-14. [Medline].

  7. Hachamovitch R, Hayes SW, Friedman JD, Cohen I, Berman DS. Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography. Circulation. 2003 Jun 17. 107(23):2900-7. [Medline].

  8. Heller LI, Cates C, Popma J, et al. Intracoronary Doppler assessment of moderate coronary artery disease: comparison with 201Tl imaging and coronary angiography. FACTS Study Group. Circulation. 1997 Jul 15. 96(2):484-90. [Medline].

  9. Zellweger MJ, Lewin HC, Lai S, et al. When to stress patients after coronary artery bypass surgery? Risk stratification in patients early and late post-CABG using stress myocardial perfusion SPECT: implications of appropriate clinical strategies. J Am Coll Cardiol. 2001 Jan. 37(1):144-52. [Medline].

  10. Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina). J Am Coll Cardiol. 2000 Sep. 36(3):970-1062. [Medline].

  11. Ryan TJ, Antman EM, Brooks NH, et al. 1999 update: ACC/AHA guidelines for the management of patients with acute myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction). J Am Coll Cardiol. 1999 Sep. 34(3):890-911. [Medline].

  12. Gibbons RJ, Balady GJ, Beasley JW, et al. ACC/AHA Guidelines for Exercise Testing. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Exercise Testing). J Am Coll Cardiol. 1997 Jul. 30(1):260-311. [Medline].

  13. Tawarahara K, Kurata C, Taguchi T, Kobayashi A, Yamazaki N. Exercise testing and thallium-201 emission computed tomography in patients with intraventricular conduction disturbances. Am J Cardiol. 1992 Jan 1. 69(1):97-102. [Medline].

  14. Updated imaging guidelines for nuclear cardiology procedures, part 1. J Nucl Cardiol. 2001 Jan-Feb. 8(1):G5-G58. [Medline].

  15. Coma-Canella I. Changes in plasma potassium during the dobutamine stress test. Int J Cardiol. 1991 Oct. 33(1):55-9. [Medline].

  16. Fazel R, Krumholz HM, Wang Y, et al. Exposure to low-dose ionizing radiation from medical imaging procedures. N Engl J Med. 2009 Aug 27. 361(9):849-57. [Medline].

  17. Stabin MG. Radiopharmaceuticals for nuclear cardiology: radiation dosimetry, uncertainties, and risk. J Nucl Med. 2008 Sep. 49(9):1555-63. [Medline].

  18. Sogbein OO, Pelletier-Galarneau M, Schindler TH, Wei L, Wells RG, Ruddy TD. New SPECT and PET radiopharmaceuticals for imaging cardiovascular disease. Biomed Res Int. 2014. 2014:942960. [Medline]. [Full Text].

  19. Einstein AJ, Blankstein R, Andrews H, Fish M, Padgett R, Hayes SW, et al. Comparison of Image Quality, Myocardial Perfusion, and Left Ventricular Function Between Standard Imaging and Single-Injection Ultra-Low-Dose Imaging Using a High-Efficiency SPECT Camera: The MILLISIEVERT Study. J Nucl Med. 2014 Jun 30. [Medline].

  20. van Dijk JD, Jager PL, Ottervanger JP, Slump CH, de Boer J, Oostdijk AH, et al. Minimizing patient-specific tracer dose in myocardial perfusion imaging using CZT SPECT. J Nucl Med Technol. 2015 Mar. 43 (1):36-40. [Medline].

  21. Palyo R, Sinusas A, Liu YH. High-Sensitivity and High-Resolution SPECT/CT Systems Provide Substantial Dose Reduction without Compromising Quantitative Precision for Assessment of Myocardial Perfusion or Function. J Nucl Med. 2016 Feb 4. [Medline].

  22. Hays JT, Mahmarian JJ, Cochran AJ, Verani MS. Dobutamine thallium-201 tomography for evaluating patients with suspected coronary artery disease unable to undergo exercise or vasodilator pharmacologic stress testing. J Am Coll Cardiol. 1993 Jun. 21(7):1583-90. [Medline].

  23. Secknus MA, Marwick TH. Evolution of dobutamine echocardiography protocols and indications: safety and side effects in 3,011 studies over 5 years. J Am Coll Cardiol. 1997 May. 29(6):1234-40. [Medline].

  24. Ranhosky A, Kempthorne-Rawson J. The safety of intravenous dipyridamole thallium myocardial perfusion imaging. Intravenous Dipyridamole Thallium Imaging Study Group. Circulation. 1990 Apr. 81(4):1205-9. [Medline].

  25. Rochmis P, Blackburn H. Exercise tests. A survey of procedures, safety, and litigation experience in approximately 170,000 tests. JAMA. 1971 Aug 23. 217(8):1061-6. [Medline].

  26. Cerqueira MD, Verani MS, Schwaiger M, Heo J, Iskandrian AS. Safety profile of adenosine stress perfusion imaging: results from the Adenoscan Multicenter Trial Registry. J Am Coll Cardiol. 1994 Feb. 23(2):384-9. [Medline].

  27. Paul AK, Nabi HA. Gated myocardial perfusion SPECT: basic principles, technical aspects, and clinical applications. J Nucl Med Technol. 2004 Dec. 32(4):179-87; quiz 188-9. [Medline].

  28. Hussain N, Parker MW, Henzlova MJ, Duvall WL. Stress-first Myocardial Perfusion Imaging. Cardiol Clin. 2016 Feb. 34 (1):59-67. [Medline].

  29. Gupta NC, Esterbrooks DJ, Hilleman DE, Mohiuddin SM. Comparison of adenosine and exercise thallium-201 single-photon emission computed tomography (SPECT) myocardial perfusion imaging. The GE SPECT Multicenter Adenosine Study Group. J Am Coll Cardiol. 1992 Feb. 19(2):248-57. [Medline].

  30. Tawarahara K, Kurata C, Taguchi T, Kobayashi A, Yamazaki N. Exercise testing and thallium-201 emission computed tomography in patients with intraventricular conduction disturbances. Am J Cardiol. 1992 Jan 1. 69(1):97-102. [Medline].

  31. Smits P, Corstens FH, Aengevaeren WR, Wackers FJ, Thien T. False-negative dipyridamole-thallium-201 myocardial imaging after caffeine infusion. J Nucl Med. 1991 Aug. 32(8):1538-41. [Medline].

  32. Smits P, Lenders JW, Thien T. Caffeine and theophylline attenuate adenosine-induced vasodilation in humans. Clin Pharmacol Ther. 1990 Oct. 48(4):410-8. [Medline].

  33. Segall GM, Davis MJ. Prone versus supine thallium myocardial SPECT: a method to decrease artifactual inferior wall defects. J Nucl Med. 1989 Apr. 30(4):548-55. [Medline].

  34. Hachamovitch R, Berman DS, Shaw LJ, et al. Incremental prognostic value of myocardial perfusion single photon emission computed tomography for the prediction of cardiac death: differential stratification for risk of cardiac death and myocardial infarction. Circulation. 1998 Feb 17. 97(6):535-43. [Medline].

  35. Gill JB, Ruddy TD, Newell JB, Finkelstein DM, Strauss HW, Boucher CA. Prognostic importance of thallium uptake by the lungs during exercise in coronary artery disease. N Engl J Med. 1987 Dec 10. 317(24):1486-9. [Medline].

  36. Rodgers GP, Ayanian JZ, Balady G, et al. American College of Cardiology/American Heart Association Clinical Competence Statement on Stress Testing. A Report of the American College of Cardiology/American Heart Association/American College of Physicians-American Society of Internal Medicine Task Force on Clinical Competence. Circulation. 2000 Oct 3. 102(14):1726-38. [Medline].

  37. Cooper JA, Neumann PH, McCandless BK. Effect of patient motion on tomographic myocardial perfusion imaging. J Nucl Med. 1992 Aug. 33(8):1566-71. [Medline].

  38. Udelson JE, Heller GV, Wackers FJ, et al. Randomized, controlled dose-ranging study of the selective adenosine A2A receptor agonist binodenoson for pharmacological stress as an adjunct to myocardial perfusion imaging. Circulation. 2004 Feb 3. 109(4):457-64. [Medline].

  39. Maublant JC, Moins N, Gachon P, Renoux M, Zhang Z, Veyre A. Uptake of technetium-99m-teboroxime in cultured myocardial cells: comparison with thallium-201 and technetium-99m-sestamibi. J Nucl Med. 1993 Feb. 34(2):255-9. [Medline].

  40. Stone JA, Dawood F, Wen W-H, et al. Is the myocardial uptake of teboroxime viability dependent?. Circulation. 1992. 86:I-707.

  41. Shehata AR, Gillam LD, Mascitelli VA, et al. Impact of acute propranolol administration on dobutamine-induced myocardial ischemia as evaluated by myocardial perfusion imaging and echocardiography. Am J Cardiol. 1997 Aug 1. 80(3):268-72. [Medline].

  42. Weich HF, Strauss HW, Pitt B. The extraction of thallium-201 by the myocardium. Circulation. 1977 Aug. 56(2):188-91. [Medline].

 
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Device summary. To acquire single-photon emission computed tomography (SPECT) images, the patient lies still in a supine position, and the gamma camera is rotated around the patient. Courtesy of Patrick J. Lynch, Yale University.
Single-photon emission computed tomography (SPECT) images compared with illustrations of the heart from similar views. The SPECT images (bottom row) show the distribution of the tracer and therefore the relative blood flow to the different regions of the myocardium. The top rows are illustrations of the heart to compare with the SPECT images from similar views. Notice there are more enhancements in the area that corresponds to the left ventricle because of its greater thickness. Courtesy of Patrick J. Lynch, Yale University.
Planar imaging. The gamma camera detects the gamma rays emitted from the tracer, and the image of where the tracer is found in the organs is transmitted to the computer. In planar technique, the computer provides a 2-dimensional myocardial perfusion image. Courtesy of Patrick J. Lynch, Yale University.
SPECT imaging performed after stress. The upper row shows short-axis slices after pharmacologic stress; the lower row shows the same slices when the body is at rest in conventional cardiac SPECT with Tc-99m tetrofosmin as a radiotracer. Arrows indicate a small perfusion defect on the backside of the heart (visible only on the stress images), showing ischemia in this region of the heart wall. Courtesy of Philipp A Kaufmann, MD, and Oliver Gämperli, MD, University Hospital Zurich.
Positioning. The patient should be supine with both arms above the head. Courtesy of Philips Healthcare.
 
 
 
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