Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 16226909

Linear response equilibrium.

Kai W Eberhardt·Michael Schär·Christoph Barmet·Jeffrey Tsao·Peter Boesiger·Sebastian Kozerke
View original source ↗Export metadata ↓

Abstract

A new periodic pulse sequence employing weak excitation is presented. This type of sequence drives the system into a steady-state with periodic time evolution from which the data can be reconstructed to a spectrum. It is demonstrated that the frequency response of such a sequence can be analyzed using perturbation methods and linear system analysis. A mathematical framework is proposed allowing the frequency response to be tailored by weighting a periodic flip function. The weak excitation level used implies very low specific absorption rates while generating a highly frequency selective signal in the order of 1/T2 with signal strengths comparable to those obtainable with conventional large flip angle balanced steady-state free precession techniques. The concept is illustrated with phantom experiments and in vivo feasibility of water fat separation is shown on human knee images.

Explore related subjects

Adipose TissueBody WaterHumansImage Processing, Computer-AssistedKnee JointMagnetic Resonance ImagingPhantoms, ImagingJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Kai W Eberhardt, Michael Schär, Christoph Barmet, Jeffrey Tsao, Peter Boesiger, Sebastian Kozerke. 2005-10-13. Linear response equilibrium.. https://doi.org/10.1016/j.jmr.2005.09.005

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2025

Rapidly decellularized adipose tissue induces soft tissue vascularization in potential anatomical spaces.

Decellularized tissues provide biological cues owing to the wealth of structural and regulatory factors that promote angiogenesis, adipogenesis, and myogenesis and facilitate neurite outgrowth. Here, we demonstrated the advantages of decellularized adipose tissue (adipoECM) over defined collagen-based biomaterials for host tissue integration. Three batches of human adipose tissue were decellularized using a rapid decellularization protocol and analyzed using mass spectrometry. To assess the biological activity of the decellularized materials, adipoECM and a reference standard of care biomaterial (Integra®DRT, also containing collagen I and glycosaminoglycans) were implanted subcutaneously, but far from the wound bed (in anatomical potential spaces) of immunocompetent BALB/c mice. The mice were euthanized in the acute (1 day) and chronic (day 60) inflammatory reaction phases, followed by biomaterial excision and Masson’s trichrome immunohistofluorescence imaging of the paraffin-embedded specimens. Each batch of processed tissue passed a quality control check, showing a low level of donor genomic DNA, lack of nuclei, lipids, endotoxins, and bacterial contamination. Mass spectrometry revealed that all batches of decellularized tissue mainly contained collagen I and, to a lesser degree, collagen III, collagen IV, collagen V, laminin, fibrillin, fibronectin, tenascin, and elastin. No acute inflammatory reaction was observed in either material one day post-transplantation. At 60 days post-implantation, different cell types were detected in adipoECM specimens, whereas Integra®DRT remained acellular. Additional immunohistochemical staining of adipoECM revealed CD31-positive cells in the blood vessels. Mesenchymal (CD90 positive) and myeloid (CD14 positive) cells were also detected. Primary cell types involved in soft tissue healing and remodeling were found in the adipoECM-treated group. The ingrowth of blood vessels and mesenchymal cells confirmed the effective integration of adipoECM with host tissues. Our results demonstrate that decellularized adipose tissue implanted away from the wound bed possesses contextual biological activities that promote efficient integration with host tissues.

Adipose Tissue↗
PubMed2007

Clinical trials in elderly patients.

The increasing size of the elderly population means that both the relative and absolute numbers of prescriptions for elderly patients are increasing. Depending on the age group, between 60% and 80% of elderly people are taking medication, and between 20% and 30% are taking at least three drugs. Prescribing for elderly patients as opposed to younger patients is thus ever more important. This has inevitably meant that the drug development process must increasingly recognise the importance of identifying and developing therapeutic targets relevant to older patients. Clearly, the scientific ethical and regulatory principles that determine conduct of clinical trials in younger individuals apply equally to older people. In addition, the development of drugs to be used in older patients requires an awareness of a number of physiological, pathophysiological and sociological considerations.

Adipose Tissue↗
PubMed2007

Body size, weight change, fat distribution and breast cancer risk in Hispanic and non-Hispanic white women.

INTRODUCTION: The incidence of breast cancer varies among women living in the Southwestern part of the US. We evaluate how body size influences breast cancer risk among these women. METHODS: Cases (n = 2,325) diagnosed with breast cancer between October 1, 1999 and May 2004 residing in Arizona, Colorado, New Mexico, or Utah were matched to controls (n = 2,525). Participants were interviewed; height, weight, waist, and hip circumference were measured at the time of interview; blood was drawn. RESULTS: A large body mass index (BMI) at age 15 was inversely associated with pre-menopausal breast cancer risk in both non-Hispanic white (NHW) and Hispanic women (Odds ratio, ORs 0.68 95% CI 0.44, 1.04, and 0.65 95% CI 0.39, 1.08, respectively); BMI at age 15 also had an impact on subsequent breast cancer associated with obesity after menopause. Among post-menopausal women, recent exposure to hormones was an important modifier of risk associated with body size. Among women not recently exposed to hormones risk associated with obesity was 1.61 (95% CI 1.05, 2.45) for NHW women; gaining > or = 25 kg between 15 and age 50 was inversely associated with breast cancer among Hispanic women (OR 0.51, 95% CI 0.23, 1.14). A large weight gain and a large waist-to-hip ratio (WHR) was associated with an increased odds of having an estrogen receptor negative tumor among NHW only (OR 1.81, 95% CI 1.07, 3.08, and 2.04 95% CI 1.20,3.50). CONCLUSIONS: These findings suggest that the metabolic consequences of obesity on breast cancer risk differ between NHW and Hispanic women living in the Southwest.

Adipose Tissue↗