Myocardial blood flow: Is motion correction necessary?

Excerpt

Quantification of myocardial blood flow (MBF) with PET has been shown to add prognostic value to myocardial perfusion imaging,1 yet some technical aspects of this promising imaging technique have not been fully examined. Like all other PET studies, myocardial studies are affected by the general limitations of the PET systems, including spill-over effects, non-ideal time-of-flight corrections and artifacts in the attenuation correction maps. One of the most critical technical limitations for myocardial perfusion PET is the possible misalignment between the PET emission data and the attenuation correction maps. In several studies, the PET to CT misalignment have been reported to introduce quantitative errors and affect the diagnostic outcome,2,3 introducing false-positive findings4-6 or even false-negative findings in some cases.2 Cardiorespiratory motion during acquisitions is another issue for MBF examinations, where the cardiorespiratory motion might introduce a general smear of the pathologic area.7-9 Related to this issue is the wear-off of the pharmaceutical agents used for stress MBF examinations, resulting in changes of the respiratory depth and frequency10-12—a problem often referred to as “myocardial creep”. This effect causes repositioning of the heart during scans, and consequently affects the time-activity curves used for the MBF evaluations.13 …