Purpose: The purpose of this study was to assess the impact of positron emission tomography/X-ray computed tomography (PET/CT) acquisition and reconstruction parameters on the assessment of mineralization process in a mouse model of atherosclerosis.
Procedures: All experiments were performed on a dedicated preclinical PET/CT system. CT was evaluated using five acquisition configurations using both a tungsten wire phantom for in-plane resolution assessment and a bar pattern phantom for cross-plane resolution. Furthermore, the radiation dose of these acquisition configurations was calculated. The PET system was assessed using longitudinal line sources to determine the optimal reconstruction parameters by measuring central resolution and its coefficient of variation. An in vivo PET study was performed using uremic ApoE-/-, non-uremic ApoE-/-, and control mice to evaluate optimal PET reconstruction parameters for the detection of sodium [18F]fluoride (Na[18F]F) aortic uptake and for quantitative measurement of Na[18F]F bone influx (Ki) with a Patlak analysis.
Results: For CT, the use of 1 × 1 and 2 × 2 binning detector mode increased both in-plane and cross-plane resolution. However, resolution improvement (163 to 62 μm for in-plane resolution) was associated with an important radiation dose increase (1.67 to 32.78 Gy). With PET, 3D-ordered subset expectation maximization (3D-OSEM) algorithm increased the central resolution compared to filtered back projection (1.42 ± 0.35 mm vs. 1.91 ± 0.08, p < 0.001). The use of 3D-OSEM with eight iterations and a zoom factor 2 yielded optimal PET resolution for preclinical study (FWHM = 0.98 mm). These PET reconstruction parameters allowed the detection of Na[18F]F aortic uptake in 3/14 ApoE-/- mice and demonstrated a decreased Ki in uremic ApoE-/- compared to non-uremic ApoE-/- and control mice (p < 0.006).
Conclusions: Optimizing reconstruction parameters significantly impacted on the assessment of mineralization process in a preclinical model of accelerated atherosclerosis using Na[18F]F PET. In addition, improving the CT resolution was associated with a dramatic radiation dose increase.
Keywords: Atherosclerosis; Bone metabolism; Na[18F]F; Preclinical PET/CT; Vascular mineralization.