Partial volume correction for improved PET quantification in 18F-NaF imaging of atherosclerotic plaques

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.Electronic supplementary materialThe online version of this article (doi:10.1007/s12350-017-0778-2) contains supplementary material, which is available to authorized users.

Hybrid Imaging: Instrumentation and Data Processing

“…Other post-reconstruction corrections consist of voxel-based methods, such as the popular Mueller-Gaertner method (MGM) [170], image deconvolution [171], and the "region-based voxel-wise correction" (RBV) [172]. Alternative approaches for PVC operate in sinogram space, where statistical noise is spatially uncorrelated and easier to incorporate in the PVC procedure [173][174][175][176]. Reconstruction-based methods enhance the spatial resolution by using the implicit PVC compensation through system-response modeling [177].…”

Optimizing arterial 18F-sodium fluoride positron emission tomography analysis

“…In this regard, positron emission tomography (PET) has shown promise 4 and the paper by Akerele et al 5 in this edition of the journal addresses an important limitation that will facilitate future research and translation into clinical practice. 18 F-Sodium Fluoride ( 18 F-NaF) is widely used for detection of bony metastases but the radiotracer also binds to early and active arterial calcifications, 6 which has generated great interest because of the potential applications in different vascular territories. In the coronary arteries, plaques with 18 F-NaF uptake detected by positron emission tomography (PET) are associated with other high-risk plaque features.…”

“…In the coronary arteries, plaques with 18 F-NaF uptake detected by positron emission tomography (PET) are associated with other high-risk plaque features. 7,8 In the carotid arteries, 18 F-NaF uptake co-locates with ipsilateral neurological symptoms. 9 In the aortic valve, 18 F-NaF uptake may assist in the prediction of progression of aortic calcification.…”

“…7,8 In the carotid arteries, 18 F-NaF uptake co-locates with ipsilateral neurological symptoms. 9 In the aortic valve, 18 F-NaF uptake may assist in the prediction of progression of aortic calcification. 10 Importantly, in the aorta, the recent SoFIA 3 study has been the first to provide insight on the potential for 18 F-NaF PET to predict the rate of progression of AAA.…”

“…This leaves only non-vertebral and importantly, aortic specific, radiotracer activity for quantification. The group tested the reconstruction method on the PET data from the cohort from the SoFIA 3 study, which remains the largest dataset of AAA-dedicated 18 F-NaF PET scans. 4 Akerele et al report that background corrected (BC) scans had a significantly lower radiotracer activity than non-background corrected scans (P = 0.013) in AAA regions, which suggests that a significant proportion of radiotracer activity within the AAA is from vertebral overspill.…”