Clinical Spotlight

Case Study

Patient History

A fifty-one year old female patient was referred for SPECT Imaging due to intermittent chest pain. The symptoms were considered atypical and not accelerating. The patient was obese (BMI 49.8), and had several risk factors including diabetes, hypertension and hyperlipidemia.

SPECT Myocardial Perfusion Imaging

The patient underwent a two day pharmacologic rest/stress SPECT study (15 mSv) with no symptoms or ECG changes. The SPECT rest and stress study images are shown in Figure A.

 

Results

The SPECT study demonstrated a medium sized and moderate in intensity anterior and anterolateral perfusion abnormality which was completely reversible. Ventricular function revealed normal wall motion globally as well as in the area of the perfusion abnormality (EF 59%).

These findings were consistent with single vessel ischemia. However, due to the patient’s body habitus, the etiology of attenuation artifact was also possible. The patient was referred for a Cardiac PET perfusion study.

Cardiac PET Myocardial Perfusion Imaging

The patient underwent a pharmacologic rest/stress PET study (5 mSv) with no symptoms or ECG changes. The SPECT rest and stress study images are shown in Figure A.

Results

The PET study demonstrated completely normal perfusion and function with a similar ejection fraction (58%) to the SPECT study Figure B.

Discussion

This study illustrates the value of Cardiac PET imaging in patients with previous SPECT studies in which attenuation artifact is a consideration. Although less common, reversible perfusion abnormalities are known to be related to attenuation artifact as was the situation in this case. Several studies have demonstrated higher diagnostic accuracy for PET over SPECT, both in terms of sensitivity, or in this case specificity (Bateman, Parker, and McArdle). Of note, radiation exposure of the PET study was 1/3 that of the SPECT.

Key Takeaways

Rubidium Advantages When Compared to Traditional Nuclear Cardiac Perfusion Procedures:

• Higher Sensitivity, Specificity and Accuracy1
• Better Resolution1,4,5
• Improved Image Quality1,5
• Lower Patient and Staff Radiation Exposure6,7
• Fewer Attenuation Artifacts6
• Improved Efficiency and Speed6
• A complete gated rest/stress PET MPI study can be performed in less than 45 minutes.8

There is Added Value With CardioGen-82® for Imaging:6,9,10

• Obese patients
• Women with Large Breasts
• Patients scheduled for pharmacological stress intervention
• Patients with Inconclusive SPECT Myocardial Perfusion Imaging studies

References

1. Bateman, et.al. Comparison of myocardial perfusion SPECT and PET. J Nucl Cardiol. 2006. Volume 13, Number 1;24-33.
2. Merhige ME. PET myocardial perfusion imaging: a new standard for the management of coronary artery disease. Ap Imaging: Ap NucCardiol. 2001;1:1-4.
3. CardioGen-82® [package insert]. Princeton, NJ: Bracco Diagnostics, Inc; 2000.
4. Chow, et.al. Prognostic significance of dipyridamole-induced ST depression in patients with normal 82Rb PET myocardial perfusion imaging. J of Nucl Med. 2005. Jul;46(7): 1095-101.
5. Yoshinaga K et.al. What is the prognostic value of myocardial perfusion imaging using Rubidium-82 Positron Emission Tomography? J AmColl Cardiol. 2006; 48:1029-1039. Yoshinaga, et. al. JACC. 2006.
6. Bateman TM. PET Myocardial Perfusion Imaging: Making the Transition to a Clinical Routine. Ap Imaging: Ap Nuc Cardiol. 2002; 3(1): 1-6.
7. Schleipman R, Castronovo FP Jr, Di Carli MF, Dorbala S. Occupational radiation dose associated with Rb-82 myocardial perfusion positron emission tomography imaging. J Nucl Cardiol. 2006; 13:3: 378-384.
8. Di Carli MF. Advances in positron emission tomography. J Nucl Cardiol. 2004;11:719-32.9. Bateman, TM. Cardiac positron emission tomography and the role of adenosine