No need for frame-wise attenuation correction in dynamic Rubidium-82 PET for myocardial blood flow quantification

Abstract

BackgroundRegadenoson-induced stress causes a repositioning of the heart, myocardial creep, in half of the patients undergoing Rubidium-82 (Rb-82) positron emission tomography (PET). As a result, misalignment of dynamic PET and computer tomography (CT) may occur, possibly affecting CT-based attenuation correction (AC) and thereby PET-based myocardial blood flow (MBF) quantification. Our aim was to determine the need for frame-wise PET-CT AC to obtain reliable MBF measurements.Methods31 Out of 64 consecutive patients had myocardial creep during regadenoson-induced stress Rb-82 PET-CT and were included. Prior to PET image reconstruction, we applied two AC methods; single PET-CT alignment and frame-wise alignment in which PET time-frames with myocardial creep were individually co-registered with CT. The PET-CT misalignment was then quantified and MBFs for the three vascular territories and whole myocardium were calculated and compared between both methods.ResultsThe magnitude of misalignment due to myocardial creep was 13.8\u2009±\u20094.5\xa0mm in caudal-cranial direction, 1.8\u2009±\u20092.1\xa0mm in medial-lateral and 2.5\u2009±\u20091.8\xa0mm in anterior-posterior direction. Frame-wise PET-CT registration did not result in different MBF measurements (P\u2009≥\u2009.07) and the magnitude of misalignment and MBF differences did not correlate (P\u2009≥\u2009.58).ConclusionThere is no need for frame-wise AC in dynamic Rb-82 PET for MBF quantification. Single alignment seems sufficient in patients with myocardial creep.