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Biomedical subjects

J E Adams

Publications and source records attributed to J E Adams.

173 records · Page 10Linked to original sources
PubMedDate not supplied

Influence of temperature on QCT: implications for mineral densitometry.

OBJECTIVE: Inaccuracies in quantitative CT (QCT) for vertebral bone mineral measurements may result from differences between the temperature of the vertebrae and the calibration standards. This study aims to quantify these effects by using scans of marrow-equivalent materials and computer simulation. MATERIALS AND METHODS: The CT numbers of fat, water, gelatin suspension, and bone were measured within an anthropomorphic phantom at temperatures between -18 and 38 degrees C. A computer simulation was then performed using these materials to represent marrow fat, soft tissue, and bone in varying proportions over this temperature range. Postprocessing single and dual energy QCT calculations were then performed on the data acquired from the simulation. RESULTS: A change of 80 HU in the CT number of water on cooling from 38 to -18 degrees C was demonstrated. An increase of 95 HU in the CT number of fat occurred over the same temperature range. Dry cortical bone showed no change in CT number with temperature changes from 24 to -18 degrees C. In the computer simulation, the fat error associated with single energy QCT for trabecular bone mineral densitometry was 20% less for specimens at room temperature than at body temperature. In simulated frozen specimens, varying marrow fat/soft tissue composition had almost no effect on single energy QCT mineral densitometry. Dual energy QCT methods that use a fat-equivalent reference material were significantly influenced by the temperature of the specimen. CONCLUSION: The fat error of single energy QCT for mineral densitometry may have been underestimated in previous in vitro studies using vertebral specimens scanned at room temperature. In the simulation, the fat error diminished as the temperature of the specimen was reduced and was negligible when frozen. Fat-equivalent reference materials used for dual energy QCT in vivo should have similar X-ray-attenuating properties at room temperature to those of marrow fat at body temperature.

Absorptiometry, Photon↗
PubMedDate not supplied

Technique and technical problems associated with implantation of neuroaugmentive devices.

The effectiveness of implantation of depth electrodes for pain control in (a) the primary thalamic relay nuclei, and (b) the periventricular gray matter or periaqueductal gray matter is reviewed. In a series of 39 patients, 14 achieved relief with no further need for medication, 16 were able to reduce their drug intake and 9 experienced no relief. These results are compared to those for a series of 76 patients reported on by an international study group of neurological surgeons. 61 patients in this series were considered to have had a successful result immediately after implantation of the electrode, but at the time of follow-up only 42 were still in this category. The implantation of depth electrodes requires a technique that fulfills the following criteria: (1) the procedure must be performed in a fully awake, cooperative patient; (2) a precise stereotactic technique must be employed, and (3) the effects of stimulation must be evaluated before the implant is made permanent. The most common complication was infection at the implantation site; this can be reduced by the use of Teflon-insulated percutaneous leads. Other complications include erosion of the hardware through the scalp and internal migration of the electrodes.

Cerebral Aqueduct↗
PubMedDate not supplied

Perspective: cerebral palsy as a model of bone development in the absence of postnatal mechanical factors.

To ensure optimal skeletal development, mechanical loading is imperative. The consequences of the removal of, or complete absence of, mechanical loading are illustrated by the clinical condition of cerebral palsy (CP). Clinical and radiological evaluation of children with CP provides an insight into how the growing skeleton develops when mechanical loading is reduced due to non-physiological muscle function. The poor bone status or "physiologic osteopenia" that these children suffer is multifactorial compromised of both mechanical and non-mechanical effects; primarily it is the lack of normal loading from the musculature which causes the development of a bone incapable of withstanding daily activities. Fractures occur during daily activities such as dressing and handling. Increased bone resorption during periods of immobilisation after fracture or surgery, also increases bone fragility. Trials of physical, nutritional and pharmacological treatments in CP children result in increased bone mineral density. Trials that include fracture prevention as the primary end point are required in this vulnerable group of children.

Bone Development↗
PubMedDate not supplied

Inotropic therapy in the home care setting: criteria, management, and implications.

The home care clients of today are requiring more intensive i.v. therapies in their home setting. The cardiac compromised patient is a prime target for this emerging trend in home infusion therapy. The end-stage cardiac patient has been traditionally treated in the hospital acute-care setting through frequent readmissions. However, there is an increasing desire by cardiac patients and their families to administer inotropic therapies in the home. Cardiac patients receiving inotropic therapy can be successfully treated in the home using specific admission criteria and monitoring guidelines.

Cardiotonic Agents↗