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Standard Myocardial Perfusion and Cardiac FDG PET Protocols and Associated Patient Radiation Doses

Sharmila Dorbala, MD, Brigham and Women’s Hospital, Boston, MA
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Myocardial perfusion positron emission tomography (PET) using 82Rb or 13N ammonia is an accurate method to evaluate rest and stress myocardial perfusion, to detect significant coronary artery disease, and to risk-stratify patients with regard to cardiac event-free survival. Compared to myocardial perfusion SPECT, PET usually provides superior image quality due to higher photon energy and inherent soft tissue attenuation correction. Coronary flow reserve may be quantified, providing a means to detect “balanced” myocardial ischemia in patients without regional perfusion abnormalities. However, because myocardial perfusion requires pharmacologic stress, exercise capacity and associated electrocardiographic abnormalities cannot be assessed. Combined with myocardial perfusion imaging, 18F-2-fluoro-2-deoxy-D-glucose (FDG) PET identifies areas of resting ischemia of viable, jeopardized myocardium where regional ischemia has resulted in a shift from fatty acid to glucose metabolism.

 Study Injected Activity  Effective Dose Estimate
 Scout scan/Localizing scan1    

  Radionuclide: 82Rb

 10 mCi 0.46 mSv2

  Radionuclide: 13N ammonia

 1 mCi 0.10 mSv3 

  Radionuclide: 18F FDG

 Use injected FDG activity to localize the heart No additional dose
 CT scout   0.73 mSv
 CT transmission scan   0.04 mSv
 Emission scan1    
 Rest/stress 82Rb -2D 40 mCi rest
40 mCi stress 		 3.76 mSv2,4
 Rest/stress 82Rb -3D 20 mCi rest
20 mCi stress		  1.88 mSv2,4
 Rest/stress 13N ammonia -2D 20 mCi rest
20 mCi stress		  3.98 mSv3
 Rest/stress 13N ammonia -3D 10 mCi rest
10 mCi stress		  1.99 mSv3
 Stress-only 82Rb -2D 40 mCi stress  1.89 mSv4
 Stress-only 82Rb -3D 20 mCi stress  0.95 mSv4
 Stress-only 13N ammonia -2D 20 mCi stress  1.99 mSv3
 Stress-only 13N ammonia -3D 10 mCi stress  0.99 mSv3
 18F FDG- 2D 10 mCi  7.03 mSv3
 18F FDG- 3D 5 mCi  3.51 mSv3

Total Patient Dose/study = (Scout dose+ transmission dose+ emission dose) + Calcium score dose (if applicable) + CT coronary angiogram dose (if applicable)
                                                                                                             

Recommendations to Decrease/Limit Patient Radiation Exposure

 

  • Follow the recommendation of the American Society of Nuclear Cardiology to decrease patient radiation exposure to < 9 mSv in 50% of patients by 20146
  • Follow appropriate use guidelines in selecting patients for myocardial perfusion PET1,7
    • Do not perform cardiac imaging in patients without cardiac symptoms unless high-risk markers for coronary events are present
    • Do not perform cardiac imaging for patients who are at low risk of coronary events
    • Do not perform radionuclide cardiac imaging as part of routine follow-up of asymptomatic patients
    • Do not perform cardiac imaging as a pre-operative assessment in patients scheduled to undergo low or intermediate risk non-cardiac surgery
  • Use 3D imaging mode and lower amounts of radiotracers whenever feasible to reduce radiation dose to the patient1
  • Use a single localizing scan and a single transmission scan if the patient is not moved between the rest and stress scans, whenever feasible, especially for Rubidium-82 imaging
  • Minimize tube current for CT based transmission imaging
  • When using gated CT imaging for calcium score, use prospective gating methods to reduce radiation dose
  • Use combined perfusion imaging and CT coronary angiogram only when the second test is indicated, after review of the results of the first test

 

References

  1. Dilsizian V, et al. PET myocardial perfusion and metabolic imaging. 2009. https://www.asnc.org/files/PET%20MP%20&%20Glucose%20Metabolism%202009.pdf
  2. Senthamizhchelvan S, Bravo PE, Esaias C et al. Human biodistribution and radiation dosimetry of 82Rb. J Nucl Med, 2010;51:1592-9. http://www.ncbi.nlm.nih.gov/pubmed/20847168
  3. Stabin MG. Radiopharmaceuticals for nuclear cardiology: radiation dosimetry, uncertainties, and risk. J Nucl Med, 2008;49:1555-63. http://www.ncbi.nlm.nih.gov/pubmed?term=Radiopharmaceuticals for nuclear cardiology: radiation dosimetry, uncertainties, and risk
  4. Senthamizhchelvan S, Bravo PE, Lodge MA, Merrill J, Bengel FM, Sgouros G. Radiation dosimetry of 82Rb in humans under pharmacologic stress. J Nucl Med, 2011;52:485-91.http://www.ncbi.nlm.nih.gov/pubmed?term=Radiation dosimetry of 82Rb in humans under pharmacologic stress
  5. Einstein AJ, Moser KW, Thompson RC, Cerqueira MD, Henzlova MJ. Radiation dose to patients from cardiac diagnostic imaging. Circulation, 2007;116:1290-305. http://circ.ahajournals.org/content/116/11/1290.full
  6. Cerqueira MD, Allman KC, Ficaro EP et al. Recommendations for reducing radiation exposure in myocardial perfusion imaging. J Nucl Cardiol, 2010;17(4):709-18. http://www.asnc.org/imageuploads/RadiationReduction060110.pdf
  7. Hendel RC, Berman DS, Di Carli MF et al. ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 Appropriate use criteria for cardiac radionuclide imaging: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the American Society of Nuclear Cardiology, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the Society of Cardiovascular Computed Tomography, the Society for Cardiovascular Magnetic Resonance, and the Society of Nuclear Medicine. J Am Coll Cardiol, 2009;53:2201-29. http://content.onlinejacc.org/article.aspx?articleid=1139755