Evaluation of an edge-based registration method: application to magnetic resonance first-pass myocardial perfusion data

Purpose

Quantification of cardiac magnetic resonance (CMR) myocardial perfusion remains time consuming since it requires manual interventions to compensate for motion. Thus, the aim of this study was to evaluate a semiautomated registration method.

Materials and Methods

A rigid edge-based registration algorithm was applied on 10 patients who had rest and stress CMR acquisitions on three slice levels (apical, midventricular and basal slices). Registration efficiency was assessed qualitatively by evaluating the quality of k-means maps in terms of symmetry and heart structures identification before and after registration and quantitatively by estimating noise amplitude within the myocardium. Finally, residual registration errors were manually estimated.

Results

Before registration, k-means maps were satisfactory for 15 of 30 slices at rest and for only 5 of 30 slices during stress. After registration, the k-means maps quality was satisfactory for 29 of 30 slices at rest and for 30 of 30 slices during stress. Moreover, registration reduced noise amplitude from 49±26 to 29±11 at rest (P<.01) and from 52±14 to 30±10 during stress (P<.01). The residual horizontal and vertical shifts were 0.06±0.12 and 0.04±0.08 mm at rest and 0.32±0.69 and 0.28±0.53 mm at stress.

Conclusion

The registration was successfully tested on rest and stress CMR perfusion data. It provides a valuable basis for quantitative evaluation of myocardial perfusion.     

HUMIC MACROMOLECULES IN NATURAL WATERS

Abstract

Humic substances are the major organic constituents of soils and sediments. They also occur in small concentrations in natural surface waters and groundwaters. They form through the breakdown of plant and animal tissues by chemical and biological processes that tend to produce complex chemical structures that are more stable than the original material from which they were derived. One of the more important characteristics of humic substances is their ability to form water-soluble and water-insoluble complexes with metal ions and hydrous oxides and to interact with clay minerals and various organic compounds such as alkanes, fatty acids, and toxic organic substances such as pesticides.     

Synthesis and Reactivity of New 1,1-Diphenyl-2,5-Dihydrophospholium Salts

Abstract

We describe the first synthesis of new 1,1-diphenyl-2,5-dihydrophospholium salts of type 1. These salts allow the access to interesting alkadienyl phosphine oxides 3 and trienes 4. Unfortunately we could not obtain the strong nucleophilic diylide 5.