Abstract
BackgroundAccurate quantification of plaque imaging using 18F-NaF PET requires partial volume correction (PVC). MethodsPVC of PET data was implemented by the use of a local projection (LP) method. LP-based PVC was evaluated with an image quality (NEMA) and with a thorax phantom with “plaque-type” lesions of 18-36 mL. The validated PVC method was then applied to a cohort of 17 patients, each with at least one plaque in the carotid or ascending aortic arteries. In total, 51 calcified (HU > 110) and 16 non-calcified plaque lesions (HU < 110) were analyzed. The lesion-to-background ratio (LBR) and the relative change of LBR (ΔLBR) were measured on PET. ResultsFollowing PVC, LBR of the spheres (NEMA phantom) was within 10% of the original values. LBR of the thoracic lesions increased by 155% to 440% when the LP-PVC method was applied to the PET images. In patients, PVC increased the LBR in both calcified [mean = 78% (−8% to 227%)] and non-calcified plaques [mean = 41%, (−9%-104%)]. ConclusionsPVC helps to improve LBR of plaque-type lesions in both phantom studies and clinical patients. Better results were obtained when the PVC method was applied to images reconstructed with point spread function modeling.
Highlights
Cardiovascular diseases (CVDs) are frequently caused by the rupture of a vulnerable atherosclerotic plaque, resulting in thrombotic occlusion or distal embolization.[1,2] Early calcium deposits are common constituents of atherosclerotic plaques, and, serve as a surrogate marker for atherosclerosis.[3]
Better results were obtained when the partial volume correction (PVC) method was applied to images reconstructed with point spread function modeling. (J Nucl Cardiol 2018;25:1742–56.)
On the right of the table, we show the lesionto-background ratio (LBR) values obtained using the tissue activities computed by the local projection (LP) method (LP - CT and LP - PET) EXP are the experimental values measured in the well counter
Summary
Cardiovascular diseases (CVDs) are frequently caused by the rupture of a vulnerable atherosclerotic plaque, resulting in thrombotic occlusion or distal embolization.[1,2] Early calcium deposits are common constituents of atherosclerotic plaques, and, serve as a surrogate marker for atherosclerosis.[3]. In view of the similarities between calcification extent and osteogenesis,3 18F-NaF uptake in PET has been described as a marker of ongoing calcium deposition in vulnerable plaque in the carotid arteries.[6,7,8,9,10] These studies, showed significant discrepancies between PET and CT findings. While the areas with positive PET uptake correlated with the CT-based calcification, only a fraction of the calcifications identified on CT images presented a significant 18F-NaF uptake. Due to the small size of the vulnerable plaques, which is comparable to the typical spatial resolution of PET, partial volume effects (PVE) may arise and compromise the quantification accuracy of 18F-NaF PET uptake in plaques. Accurate quantification of plaque imaging using 18F-NaF PET requires partial volume correction (PVC)
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