Article

Simplified parametric methods for [11C]PIB studies

Department of Nuclear Medicine and PET Research, VU University Medical Centre, PO Box 7057, 1007 MB Amsterdam, The Netherlands.
NeuroImage (Impact Factor: 6.36). 09/2008; 42(1):76-86. DOI: 10.1016/j.neuroimage.2008.04.251
Source: PubMed

ABSTRACT The purpose of the present study was to evaluate the performance of various parametric reference tissue models for quantification of [11C]PIB studies. Several models with and without fixing the reference tissue efflux rate constant (k'(2)) were investigated using both simulations and clinical data. The following parametric methods were evaluated: receptor parametric mapping (basis function implementation of the simplified reference tissue model with and without fixed k'(2)), reference Logan, and several multi-linear reference tissue methods (again with and without fixed k'(2)). In addition, standardised uptake value ratios with cerebellum (SUV(r)) were evaluated. Simulations were used to assess the effects of variation in flow (R(1)), fractional blood volume (V(b)) and binding potential (BP(ND)) itself on precision and accuracy of parametric BP(ND). For clinical studies, most parametric methods showed comparable performance, with poorest results for SUV(r). Best performance was obtained for receptor parametric mapping (RPM2) and one of the multi-linear reference tissue models (MRTM2), both with fixed k'(2): BP(ND) outcome was less affected by noise and the images showed better contrast than other tested methods. RPM2 and MRTM2 also provided best accuracy and precision in the simulation studies and are therefore the methods of choice for parametric analysis of clinical [11C]PIB studies.

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    • "Our two subjects with presenilin-1 mutations, in the absence of memory loss, both had higher RATIO PONS in the cortex and the cerebellum than the mean control values whereas RATIO CER underestimated the [ 11 C]PIB binding differences (Table 4). Studies have examined the reproducibility of [ 11 C]PIB using different methods of analysis (Aalto et al., 2009; Edison et al., 2009; Engler et al., 2006; Lopresti et al., 2005; Price et al., 2005) and have shown that reference tissue methods perform better than the arterial input method of analysis for discrimination of AD from healthy normals, while the target-to-cerebellum ratio performed better than the other simplified methods of analysis in terms of sensitivity and reproducibility (Yaqub et al., 2008). Here, the target-to-pons ratio demonstrated high sensitivity for detecting AD and gave comparable test–retest reproducibility to RATIO CER . "
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    • "(R)-[ 11 C]verapamil BP ND values in the two patients that were visually classified as PIB negative were in the range of the PIB-positive patients with Alzheimer's disease. Quantitatively, however, these two patients did show some amount of increased [ 11 C]PIB binding with RPM2-derived (Yaqub et al., 2008) global C]PIB BP ND values of 0.19 and 0.34, respectively. Although this is increased compared with healthy controls, it is still below the threshold of [ 11 C]PIB BP ND of 0.54 for being [ 11 C]PIB positive (Tolboom et al., 2010). "
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    • "The simulated data are adopted from published clinical data, [12] [15]. Specifically, arterial input function and rate constants of two tissue reversible compartmental model for PIB tracer are used. "
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