DSCT Myocardial perfusion versus SPECT CT myocardial perfusion
The following question has been sent by Dr. Shrinivas Desai:
DSCT Myocardial perfusion versus SPECT CT myocardial perfusion:
Jaslok Hospital in mumbai, India is buying Siemens DSCT (Flash Definition Dual source Dual energy). We already have a SPECT on which thallium myocardial perfusion is done. The nuclear medicine department is considering acquiring SPECT-CT with rubidium to perform myocardial perfusion. Jaslok Hospital is a stand alone private hospital with 350 beds with moderate cardiac workload. In your opinion will it be viable for a hospital to possess both Siemens DSCT (Flash Definition Dual source Dual energy) and SPECT-CT for the purpose of myocardial perfusion. Will the myocardial perfusion done on the dual source CT give results comparable to SPECT-CT or are both needed?
With warm regards.
Dr. Shrinivas Desai, Mumbai.
Balasz Ruzsics, M.D., Medical University of South Carolina:
Dear Dr. Shrinivas,
Thank you for the question and your interest in DSCT.com website.
Dual source CT technology in dual energy mode is a promising tool for detecting myocardial ischemia. To date initial experience studies established the potential role of dual energy CT (DECT) acquisitions for detecting not just the coronary stenosis but corresponding myocardial blood pool defect. DECT successfully combined anatomical (coronary artery) and functional (myocardium) imaging information.
It is also well known that SPECT may create false positive results because of breast and/or bowel attenuation. Moreover nuclear perfusion imaging of the heart is based on relative numbers as the uptake of radionuclides in different myocardial territories is compared. Since patients with severe disease in one vessel tend to also have some disease in the other vessels, the relative difference in myocardial perfusion is reduced; therefore global hypoperfusion (i.e. balanced ischemia) is a known diagnostic pitfall for the assessment of 3-vessel CAD in nuclear perfusion studies.
Our recommendation is to try to use dual energy in those patients who are susceptible of myocardial ischemia. Using dual energy mode no information can be lost regarding identification and characterization of coronary artery stenosis with a cost of no further radiation of patient. Merging information of high and low tube voltage enables to delineate myocardial blood pool defect. Combining information of myocardial ischemia and stenosis grading helps the reader to decide precisely the significance of the stenosis which is hard to do with using only regular coronary CTA.
Beside the presented evidences, it is worthy to note that DECT is an important asset to the clinical workflow but cannot be used exclusively as one-stop-shop modality in patients with coronary artery disease. Future research, multicenter studies are warranted to explore the true usefulness of the technique in day to day clinical routine. That is the reason why, at this stage dual energy CT acquisition cannot replace clinical standard SPECT myocardial perfusion imaging. Thus it is highly recommended to have both SPECT and Dual Source Flash Definition scanners.
I hope that this answers to your questions. Please do not hesitate to contact me if you have further questions.
Best regards,
Balazs Ruzsics
