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Biomedical subjects

J Patterson

Publications and source records attributed to J Patterson.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Digital mapping of multi-parameter contrast functions in magnetic resonance (MR) imaging using a standard MR computer system and digital display.

A technique is described which utilises the full analysis and display capabilities of a commercial MRI system to produce digital maps of multi-parameter functions produced by MR contrast theory. The technique is utilised to determine the effects of nominating specific overall scan times on the optimum solutions as produced by the theory and it is shown that different solutions are obtained when the theory is applied using typical clinical constraints. The digital mapping approach is potentially of great value in prospectively determining pulse timing parameters to produce optimum contrast images, in producing contrast maps to aid retrospective image interpretation, and as a training aid for clinicians inexperienced in the interpretation MR images.

Computer Graphics↗
PubMedDate not supplied

The use of in vitro magnetic resonance tissue studies to optimise pulse sequences in the imaging of intracranial haemorrhage.

The choice of appropriate MR pulse sequences to highlight a particular pathology to best advantage is not always straightforward. In this study of intracranial haemorrhage, tissue relaxation times measured in vitro were entered into a computer program which calculated the signal intensity of each tissue (brain, blood, CSF, and bloody CSF) for all possible echo (TE) and repeat (TR) times. Analysis of graph plots of the results enabled the selection of pulse sequences which gave optimal separation of the signal intensities of intracranial haemorrhage from those of normal intracranial contents. The sequences thus chosen were used successfully in the imaging of patients with intracranial haemorrhage.

Cerebral Hemorrhage↗
PubMedDate not supplied

Combining behavioral and self-help approaches in the inpatient management of dually diagnosed patients.

The combination of a token economy and a self-help model made it feasible to organize and maintain an intensive dual-diagnosis treatment program in a public municipal hospital acute psychiatric ward. The program described here, which integrates the token economy and 12-step approaches, fosters voluntary and active patient participation in the process of simultaneous recovery from mental illness and addiction; it also networks the patient with community resources. Implementation of the clinical program involved addressing multiple clinical and organizational obstacles, including a multihandicapped and often nonmotivated patient population, a lack of psychiatric staff trained in managing substance abuse, and the need to integrate mental health with substance abuse clinical interventions. The program has been operating more than 5 years and has treated more than 1,000 patients. As the token economy became an integral part of the ward routine, violence on the ward declined substantially, and patient participation in group activities increased significantly.

Activities of Daily Living↗
PubMedDate not supplied

123Iodo-MK-801: a spect agent for imaging the pattern and extent of glutamate (NMDA) receptor activation in Alzheimer's disease.

Glutamate, and the NMDA glutamate receptor, may be involved in Alzheimer's Disease (AD). Reductions in NMDA receptors are found in AD, possibly contributing to memory deficits. However the NMDA receptor is involved in excitotoxicity, which may play a role in cell death and the production of neurofibrillary tangles in AD; although with lower levels of glutamate than occur in cerebral ischaemia. Therefore reductions in the NMDA receptor may worsen memory deficit in AD, but increased stimulation of the receptor may contribute to the progress of the disease. MK-801 has been used to image excessive glutamate activation following ischaemia in rats. However, it is unclear how effective MK-801 is in conditions with lower levels of glutamate release. This study attempts to gain insight into the utility of the tracer in these conditions, exploring glutamatergic mechanisms in AD. It describes the retention and elimination of 123iodo-MK-801 in five AD and five control subjects, comparing this to regional cerebral blood flow (rCBF). The initial uptake of 123I-MK-801 is dominated by delivery of the ligand. However, despite significant reductions in rCBF in the AD patients, there is no significant difference in the uptake of 123I-MK-801. This suggests increased retention of 123I-MK-801 in the AD patients. In addition the washout of 123I-MK-801 was less in the AD patients, again suggesting increased retention, although this only reached significance in one region. Theses data hint at possible increases in NMDA activation in AD but ultimately 123I-MK-801 does not provide a sufficiently accurate measurement to demonstrate this conclusively. Further NMDA ligands are now at a late stage of development and may provide more conclusive answers to the role of glutamate in AD.

Aged↗
PubMedDate not supplied

A new method for rapid fluid bolus infusion into a peripheral vein.

OBJECTIVE: To compare the flow rates achieved by a new short-tubed infusion device with those obtained with a conventional apparatus, using gravity, manual pressure, and pneumatic inflation as the driving forces. METHODS: Ten paramedic volunteers were recruited for this prospective, randomized, controlled laboratory study. For the short-tubing setup, a new device, the port, was used to adapt standard 18-cm extension tubing directly to an i.v. bag [short tubing/port (STP) setup]. For the conventional (CON) setup, 280-cm tubing was used. Both study setups were tested on each of the volunteers with flow from a standard 250-mL bag of normal saline subjected to three types of driving force: 1) gravity alone, 2) pressure supplied by two hands squeezing the i.v. bag, and 3) a pneumatic pressure bag continuously inflated to 300 mm Hg. The mean flow rates for each driving force were compared between the two setups. RESULTS: Using gravity flow, no significant difference was noted between the STP setup and the CON setup (0.40 vs 0.45 mL/sec, respectively, p > 0.4). However, when flow was augmented by pressure supplied by two hands squeezing the bag, mean flow was greater for the STP setup than for the CON setup (4.5 vs 2.7 mL/sec, respectively, p < 0.001). When flow was augmented by a pneumatic bag at 300 mm Hg, mean flow was again greater for the STP setup (5.6 mL/sec) than for the CON setup (3.3 mL/sec, p < 0.001). CONCLUSION: Flow of crystalloid under pressure into a peripheral vein is markedly increased with the new STP setup as compared with the CON setup. Incorporation of this new setup in prehospital care would allow EMS personnel to infuse fluid more rapidly and conveniently during transport.

Adult↗
PubMedDate not supplied

Development of an inservice educational program for clinical staff.

Inservice education is potentially one of the most effective tools of the clinical engineer. A good technical inservice program can significantly reduce the amount of time engineers and technicians must spend on repetitive, corrective tasks, allowing them to be of greater value to their institutions in more creative ways. A complete technical inservice education program has been designed for the University of Connecticut Health Center's John Dempsey Hospital. To design such a program, one must first assess current inservice practices and any associated problems, as well as the educational needs of the clinical staff. The assessment is done by examining past equipment repair records, and by surveying nurses and other clinicians within the hospital, clinical engineers from outside hospitals, and equipment vendors. A sample program is then carried out to gather additional information and gain the acceptance and support of key hospital personnel. Based on the compiled data, an inservice program is proposed that is streamlined to maintain a desirable level of efficacy without requiring an inordinate amount of time. Quantitative analyses of costs and benefits confirm that the proposed program will have a net positive effect.

Biomedical Engineering↗
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A quantitative index of ventricular and extraventricular intracranial CSF volumes using MR imaging.

A new technique is described that utilises a novel magnetic resonance pulse sequence to produce a quantitative index both for ventricular and, for the first time, extraventricular intracranial CSF volumes. The pulse sequence is a combination of a null-point inversion recovery sequence with an extended spin-echo read (echo time = 400 ms), which produces a contrast of CSF to white or grey matter of approximately 120:1. A series of experiments are performed on phantoms representing CSF filled ventricles and sulci over a wide range of volume values, and it is found that the standard deviation of differences between true and estimated values is 3.9% for ventricles, 4.6% for total cranial CSF, and 7.9% for CSF within the sulci. Normal volunteer reproducibility studies revealed corresponding standard deviations of less than 5.5%. Using the technique to produce absolute estimates of CSF volumes in normal subjects and patients produced results in good agreement with previously published necropsy studies. The technique has wide neurological and neurosurgical applicability particularly in terms of differential diagnosis and as an objective monitor of therapy or progression in conditions such as hydrocephalus, atrophy, and benign intracranial hypertension.

Adolescent↗
PubMedDate not supplied

MR relaxation times of cerebrospinal fluid.

A review of 15 recent publications purporting to provide the relaxation times of CSF reveals a considerable disparity in the quoted results, by a factor of five in terms of T1 (range 1,000 to 5,500 ms) and by a factor of 16 for T2 (range 166 to 2,640 ms). In this article measurements are performed independently on both a spectrometer and an imager. The results indicate that for CSF T1 is greater than 3,000 ms and T2 is approximately 2,000 ms at 6 MHz. The vast differences in relaxation behaviour between CSF and other body tissues have considerable clinical implications and present profound diagnostic opportunities. The application of this knowledge to ventriculography, myelography, and image contrast methodology is discussed.

Cerebrospinal Fluid↗
PubMedDate not supplied

Is cranial CSF volume under hormonal influence? An MR study.

We used magnetic resonance to investigate the hypothesis that premenstrual neurological symptoms are due to cerebral oedema and brain swelling. Total cranial and lateral ventricular CSF volumes were measured midcycle and premenstrually in 20 women with a normal menstrual cycle, and similar measurements were made 2 weeks apart in 10 postmenopausal women and 10 men. Total cranial CSF volume increased premenstrually in 19 women. The mean premenstrual increase was by 11.5 ml. There was not a significant difference between those women who were taking an oral contraceptive and those who were not. The CSF volume did not change significantly on repeat measurement in men and postmenopausal women. The CSF changes observed reflect a reduction in brain volume and do not support cerebral swelling as the cause of premenstrual neurological symptoms.

Adult↗
PubMedDate not supplied

Effects of level of retrieval success on recall-related frontal and medial temporal lobe activations.

Brain dedicated single photon emission computed tomography (SPECT) was used to compare the neuroactivation produced by the cued recall of response words in a set of studied word pairs with that produced by the cued retrieval of words semantically related to unstudied stimulus words. Six of the 12 subjects scanned were extensively trained so as to have good memory of the studied pairs and the remaining six were minimally trained so as to have poor memory. When comparing episodic with semantic retrieval, the well-trained subjects showed significant left medial temporal lobe activation, which was also significantly greater than that shown by the poorly trained subjects, who failed to show significant medial temporal lobe activation. In contrast, the poorly trained subjects showed significant bilateral frontal lobe activation, which was significantly greater than that shown by the well-trained subjects who failed to show significant frontal lobe activation. The frontal activations occurred mainly in the dorsolateral region, but extended into the ventrolateral and, to a lesser extent, the frontal polar regions. It is argued that whereas the medial temporal lobe activation increased as the proportion of response words successfully recalled increased, the bilateral frontal lobe activation increased in proportion to retrieval effort, which was greater when learning had been less good.

Adult↗
PubMedDate not supplied

Paramedic interpretation of prehospital lead-II ST-segments.

OBJECTIVE: To determine the reliability of ST-segment interpretation by paramedics from lead-II rhythm strips obtained in the prehospital setting. DESIGN: Prospective, blinded study of 127 patients transported by an urban/rural emergency medical services system with complaints consistent with ischemic heart disease. METHODS: Emergency department physicians asked emergency medical technician-paramedics (EMT-P) via radio to evaluate ST-segments for elevation or depression and grade it as "mild," "moderate," or "severe." Then, this rhythm strip was interpreted blindly by emergency physicians who also interpreted the lead-II obtained from a 12-lead electrocardiogram (ECG) obtained in the emergency department (ED). The field interpretation was compared with the subsequent readings and the final in-patient diagnosis using positive predictive value (PPV), negative predictive value (NPV), and the Kappa statistic. Markedly discrepant interpretations were analyzed separately. RESULTS: Using physician interpretation as the reference standard, paramedic interpretation of the lead-II ST-segments obtained in the prehospital setting was correct (within +/- 1 gradation) in 113 out of 127 total cases (89%). Of 105 patients for whom final hospital diagnosis was available, the ST-segment on the rhythm strip obtained in the prehospital setting, had a positive predictive value of 74% and a negative predictive value of 85% for myocardial ischemia or myocardial infarction (MI) (p < 0.001, Kappa = 0.59). Discordant interpretations between the paramedics and emergency physicians often were related to a basic misunderstanding of rhythm strip morphology. CONCLUSION: Field interpretation of ST-segments by paramedics is fairly accurate as judged both by emergency physicians and correlation with final patient outcome, but its clinical utility is unproved. A small but clinically significant number of outliers, consisting of markedly discrepant false positives, reflects paramedic uncertainty in identifying the deviations of the ST-segment.

Adult↗
PubMedDate not supplied

Impact of a comprehensive health promotion curriculum on physician behavior and attitudes.

Physician involvement with health promotion and disease prevention (HP/DP) is essential in the control of diseases in which behavioral risk factors are etiologically important. Yet physician involvement with health promotion is generally perceived as less than optimal. We report that an intensive, multifactorial curriculum introduced into a community hospital family medicine residency program increased physicians' use of preventive strategies with their patients and facilitated their use of specific, easy-to-follow protocols for the management of common problems amenable to health promotion.

Attitude of Health Personnel↗