Cardiac PET/CT Fills in Gaps Left by SPECT

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  Daniel Berman, MD, director of cardiac imaging and nuclear cardiology, Cedars-Sinai Medical Center

As SPECT imaging migrates to private physicians offices, PET/CT provides hospitals an opportunity to recapture some of that business.

Cardiac imaging is in a state of evolution with traditional techniques giving way to advanced imaging tools that promise to improve diagnosis and treatment and also help hospitals grow their cardiac imaging services. High-resolution PET/CT is one such technology. Cedars-Sinai Medical Center in Los Angeles, Calif., is one of a handful of institutions leading the charge in cardiac imaging by deploying the latest 64-slice hybrid imaging technology in its cardiology department.

Cedars-Sinai Medical Center ranks among the country’s best, and its commitment to leading-edge research and excellence in the non-invasive cardiac imaging program is recognized worldwide. Performed in the S. Mark Taper Foundation Imaging Center at Cedars-Sinai, the center’s non-invasive cardiac imaging services include nuclear cardiology with PET and SPECT, cardiac MRI, and dual-source cardiac CT.

Daniel Berman, MD, director of cardiac imaging and nuclear cardiology and a world-renowned expert in nuclear cardiology and cardiac imaging, is the chief architect of Cedars-Sinai’s cardiac PET/CT program. He discusses the shortfalls of current cardiac imaging tools and peers into current applications as well as the future promise of high-resolution cardiac PET/CT.

Q: For years, SPECT has been the tried-and-true nuclear cardiology cardiac imaging tool. Does SPECT fully meet cardiac imaging needs?

A: No. In fact, the drawbacks to cardiac SPECT are well-known and widespread. The most troublesome drawback is that SPECT often underestimates myocardial perfusion abnormalities. It’s possible and not uncommon for patients with advanced multi-vessel disease to have a balanced reduction in blood flow. Uniform reduction in blood flow can be interpreted as normal myocardial perfusion. In these cases, the SPECT study may be read as normal, so cardiologists may miss some patients with advanced disease.

Q: Clearly, there is room for improvement. Does high-resolution cardiac PET/CT improve on SPECT imaging?

A: Hybrid PET/CT brings cardiac imaging new opportunities; its advantages fall into several categories.

For starters, image quality is clearer. Systems like ours, the Siemens Biograph 64, offer higher resolution than SPECT cameras with the added benefit of very effective attenuation correction. Both sensitivity and specificity are higher than SPECT. These advantages translate into fewer inconclusive results, which may translate into fewer follow-up studies, optimizing both the physician’s and patient’s time and enabling cardiologists to begin any necessary interventions in a timelier manner.

In addition, unlike SPECT, which does not allow image acquisition during exercise-induced stress, cardiologists can image patients during stress with PET/CT. With SPECT, the assessment of function is performed after stress when stress-induced abnormalities of ventricular function may have resolved. With PET/CT, on the other hand, physicians can compare vasodilator stress to rest and thus view and analyze the effects of stress on the heart muscle.

Finally, PET/CT provides the potential to calculate blood flow and determine whether or not blood flow is diminished in a particular region of the heart. SPECT does not allow cardiologists to measure myocardial blood flow in specific regions.

Q: PET/CT can provide additional diagnostic information and benefit patients with uniform reductions in blood flow. Are there other patient populations that may benefit from PET/CT rather than SPECT studies?

A: Absolutely. SPECT tends to produce attenuation artifacts in certain patients, particularly obese patients and large-breasted women. PET/CT provides excellent attenuation correction, so it is well-suited to these patients. I believe that certain Cedars-Sinai patients will see an immediate benefit with the deployment of our PET/CT scanner: patients with an equivocal nuclear scan and initial studies for obese and large-breasted patients.

Q: Hospitals need to consider questions beyond the clinical advantages of technologies such as PET/CT. In the current fiscal climate, any investments should be cost-justified. What are the economic, throughput or competitive advantages to adding cardiac PET/CT to a facility’s imaging portfolio?

A: Hospitals have seen a significant