We have previously described an approach to 3D intracerebral vascular reconstruction that uses an MRA as a reconstruction base. Additional vessels seen only by angiography are added by segmenting 2D curves from projection angiograms and reconstructing these curves into 3D, building upon the MRA. Intracerebral vascular reconstruction is difficult for at least two reasons. First, 2D curves must be associated on projection images even when the human eye cannot do so. Second, 3D curves must be reconstructed in the presence of errors such as misregistration, image distortion, and misdefinition of 2D curves. This paper is the first of two that address the specific issue of reconstruction of a 3D curve from a given pair of 2D curves in the presence of error. The method explicitly separates what can and cannot be determined from a pair of projection views. It is also capable of recognizing interruptions produced by viewplane errors, of continuing reconstruction beyond such interruptions, and of localizing and estimating the magnitude of the interruptions. These measurements can also be used to estimate the lengths of regional disparities between a pair of 2D curves, leading to a quantitative estimate of the capacity of a pair of 2D curves to combine to create a 3D object (match value). Match values can be used, in turn, as part of the strategy for automatically associating pairs of 2D curves. This paper provides methods for reconstructing a given pair of 2D curves into 3D in the presence of error and for calculating match values. Error analysis is given in the companion report.
We have previously described an approach to 3D intracerebral vascular reconstruction that uses an MRA as a reconstruction base. Additional vessels seen only by angiography are added by segmenting 2D curves from projection angiograms and reconstructing these curves into 3D, building upon the MRA. This paper is the second of two that discuss the specific problem of reconstructing a 3D curve from a given pair of 2D curves in the presence of error. The method presented is capable of detecting and handling many errors produced by misregistration, image distortion, or misdefinition of 2D curves. The first paper gives an algorithm. The current paper discusses factors affecting the accuracy of a reconstructed curve, with emphasis upon registration error. We analyze the spatial accuracy of a reconstructed point in terms of the relationships between pixel size, relative viewing angle, 3D point location, and registration error. We provide a theoretical framework that, given the known error properties of a registration algorithm, allows optimization of the viewing geometry so as to produce the highest precision of point reconstruction. A major focus is the effect of registration error upon the reconstruction of a curve. We subdivide registration error into two types, one of which produces smoothly continuous point placement errors and the other of which produces pixel pairing errors. We test our ability to reconstruct a 3D curve in the presence of both. Finally, we summarize approaches to other sources of error. We conclude with a list of recommendations to optimize reconstruction accuracy. When projection points are associated by the rules of epipolar geometry, viewplane point displacements should not exceed 1.5-2 mm along the axis perpendicular to epipolar planes.
that the intersection of key sociodemographics and poverty has a robust and, in some cases, deleterious effect on pain. This provides important insight into how social determinants of health may contribute to pain disparities.
knowledge, the association between pain and itch symptoms at the tissue autograft site after MThBI has not previously been assessed. We evaluated tissue autograft pain and itch severity (0-10 NRS) during the inflammatory and early proliferative phases (0-2 weeks) and late proliferative and maturation phase (3 weeks-6 months) of wound healing among a cohort of burn survivors (n=96) who received tissue autografting within 14 days of MThBI. Associations between pain and itch symptoms on days 1, 14, week 6, and months 3 and 6 were evaluated using Pearson correlation coefficients (SPSS Statistics v23). Acute pain and acute itch are not significantly correlated in the inflammatory and early proliferative phases of wound healing (e.g., r = 0.223, p = 0.055 at 14 days post-op). However, during the proliferative and maturation phase (3 weeks-6 months) chronic pain and chronic itch symptoms demonstrated significant and progressively increasing correlation (e.g., r=0.397, p=7.3 x 10-6 at month 3 and r=0.532, p=1.143 x 10-8 at month 6). These epidemiologic data suggest that neural, glial, and immune mechanisms mediating tissue autograft pain and itch symptoms evolve after MThBI such that they are increasingly comorbid. Further studies are needed to understand mechanisms mediating these outcomes; such studies may inform the development of improved preventive/treatment interventions. (Liu, Pflugers Arch, 2013.
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