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BACKGROUND AND PURPOSE: Iterative reconstruction has promise in lowering the radiation dose without compromising image quality, but its full potential has not yet been realized. While phantom studies cannot fully approximate the subjective effects on image quality, live animal models afford this assessment. We characterize dose reduction in head CT by applying advanced modeled iterative reconstruction (ADMIRE) in a live ovine model while evaluating preservation of gray-white matter detectability and image texture compared with filtered back-projection. MATERIALS AND METHODS: A live sheep was scanned on a Force CT scanner (Siemens) at 12 dose levels (82-982 effective mAs). Images were reconstructed with filtered back-projection and ADMIRE (strengths, 1-5). A total of 72 combinations (12 doses  6 reconstructions) were evaluated qualitatively for resemblance to the reference image (highest dose with filtered back-projection) using 2 metrics: detectability of gray-white matter differentiation and noise-versus-smoothness in image texture. Quantitative analysis for noise, SNR, and contrast-to-noise was also performed across all dose-strength combinations.

BACKGROUND AND PURPOSE:Interpretation of fMRI depends on accurate functional-to-structural alignment. This study explores registration methods used by FDA-approved software for clinical fMRI and aims to answer the following question: What is the degree of misalignment when registration is not performed, and how well do current registration methods perform? MATERIALS AND METHODS:This retrospective study of presurgical fMRI for brain tumors compares nonregistered images and 5 registration cost functions: Hellinger, mutual information, normalized mutual information, correlation ratio, and local Pearson correlation. To adjudicate the accuracy of coregistration, we edge-enhanced echo-planar maps and rated them for alignment with structural anatomy. Lesion-to-activation distances were measured to evaluate the effects of different cost functions. RESULTS:Transformation parameters were congruent among Hellinger, mutual information, normalized mutual information, and the correlation ratio but divergent from the local Pearson correlation. Edge-enhanced images validated the local Pearson correlation as the most accurate. Hellinger worsened misalignment in 59% of cases, primarily exaggerating the inferior translation; no cases were worsened by the local Pearson correlation. Three hundred twenty lesion-to-activation distances from 25 patients were analyzed among nonregistered images, Hellinger, and the local Pearson correlation. ANOVA analysis revealed significant differences in the coronal (P Ͻ .001) and sagittal (P ϭ .04) planes. If registration is not performed, 8% of cases may have a Ͼ3-mm discrepancy and up to a 5.6-mm lesion-toactivation distance difference. If a poor registration method is used, 23% of cases may have a Ͼ3-mm discrepancy and up to a 6.9-mm difference. CONCLUSIONS:The local Pearson correlation is a special-purpose cost function specifically designed for T2*-T1 coregistration and should be more widely incorporated into software tools as a better method for coregistration in clinical fMRI. ABBREVIATIONS: AFNI ϭ Analysis of Functional Neuro Images; CR ϭ correlation ratio; HEL ϭ Hellinger; LAD ϭ lesion-to-activation distance; LPC ϭ local Pearson correlation; MI ϭ mutual information; NMI ϭ normalized mutual information; NR ϭ nonregistered

Recently, I proposed a theory of ontology for the Godworld relation that draws inspiration from: Deacon's emergent dynamics where absence plays a role in causal work; dispositionalism as the most suitable philosophical tradition for accommodating absence as a mode of being; and Palamism as the most suitable theological framework for articulating the absence of God as presence. Dumsday's "Palamism and Dispositionalism" in the present issue of Zygon is a cogent breakdown of that thesis, exposing philosophical and theological worries that touch on pan-dispositionalism, bundle theory, Platonism, divine essence, created-uncreated distinction, God-world synergy, and more. This response article engages with the landscape of ideas that Dumsday surveys in an attempt to clarify and extend the proposed thesis that nature's powers are God's energies.