Biomedical subjects

D R Pickens

Publications and source records attributed to D R Pickens.

10 recordsLinked to original sources

PubMed1992

Clinical impact of picture archiving and communication systems: evaluation of a prototype system.

Opinion surveys were gathered before and 6 months after installation of a prototype picture archiving and communication system (PACS) (PACS/1, Siemens Medical Systems, Iselin, NJ). Median turnaround times and the percent of delayed or missing reports were calculated for 1,026 baseline and 8,438 follow-up studies at 6 months. Neuroradiological (neuro) computed tomography (CT) used PACS, while neuro magnetic resonance (MR), body CT, and body MR served as controls. The opinion surveys showed improved service in all categories, including those not directly affected by PACS. PACS images favorably impressed 86% of respondents, but most considered the system too slow, unreliable, and the storage capacity too low. A majority of 81% recommended against purchase of PACS now. There was an overall increase in the median report turnaround time for both neuro CT and the controls. Neuro CT showed a 41% decrease in delayed or missing reports, but controls also showed similar decreases. The effects of this prototype PACS on turnaround time or on report delivery could not be distinguished from section-wide changes in CT and MR services. Future improvements in PACS should vigorously address increased speed, reliability, and storage capacity.

Attitude of Health Personnel↗

PubMed1992

Magnetic resonance perfusion/diffusion imaging of the excised dog kidney.

RATIONALE AND OBJECTIVES: The authors developed a model of tissue capillary beds applicable to perfusion/diffusion imaging with magnetic resonance imaging (MRI). The model consists of a formalin-fixed excised dog kidney attached to a variable speed pump. With this system, it is possible to perfuse the kidney at selected rates. METHODS: Using the intravoxel incoherent motion model (IVIM), the apparent diffusion coefficient (ADC), diffusion coefficient (D), and perfusion fraction (f) were computed for a region of interest (ROI) in the renal cortex and in the medulla of seven kidneys, one of which was injected with a vasodilator before fixation. ADC and D values were computed for both cortex and medulla. These values were normalized to zero flow and plotted against renal perfusion. The perfusion fraction f was expressed in percent and was not normalized to zero flow. RESULTS: Normalized ADC and f were correlated with tissue perfusion rates using the Spearman rank-sum test (n = 18, rs greater than 0.5, P less than or equal to .02 for the standard preparation in both cortex and medulla), whereas normalized D (rs much less than 0.5) was uncorrelated for both preparations in cortex and medulla. CONCLUSIONS: The isolated perfused dog kidney is a useful model of tissue capillary beds for perfusion imaging technique development. The perfusion/diffusion-related parameters ADC and f increase as flow increases in the tissues, whereas D does not.

Animals↗

PubMed1992

Perfusion/diffusion quantitation with magnetic resonance imaging.

Quantitation of perfusion and diffusion in tissues using magnetic resonance imaging (MRI) techniques is an active area of research in many laboratories. Several different approaches have been taken to address the problem of determining microcirculatory flow or perfusion in the body with MRI. Methods have been developed that depend on pulse sequence designs to sensitize the acquisitions to proton movement that is part of physiologic perfusion. Other methods that are being studied take a different approach by using injected MR contrast agents coupled with high temporal resolution acquisitions to produce time-density curves that can be related to perfusion in the tissues of interest. Yet other approaches use blood as the tracer itself to provide a means of determining perfusion. All of these techniques and others provide quantitative information related to microcirculatory flow in tissues.

Animals↗

PubMed1991

Magnetic resonance diffusion/perfusion phantom experiments.

Recently, several models for determining microcirculatory parameters using magnetic resonance imaging have been proposed. These include the intravoxel incoherent motion (IVIM) model, the intravoxel coherent motion (IVCM) model, and various tracer models. In order to evaluate these models before extension into physiological systems, phantom studies were used to assess model assumptions, measurement uncertainties, and sensitivity to changes in perfusion. Emphasis is placed on the IVIM model, but the techniques discussed could be extended to evaluation of other models as well. An overview of considerations in pulse sequence development, phantom design, and data interpretation is presented for a variety of phantoms ranging in complexity from stationary volumes of fluid and mechanically pumped phantoms to isolated animal kidneys and finally to an in vivo animal model.

Animals↗

PubMed1990

Qualitative and quantitative evaluation of charge capture by a radiology information system.

Installation of a radiology information management system (RIS) is usually justified on the basis of improved departmental efficiency and improved charge capture. However, evaluation of the success of these expected improvements is often difficult. The installation and operation of such a system in a medium-sized tertiary care hospital has permitted the effects of the RIS on the operation of the department to be studied and the improvements in charge capture provided by the system to be quantitatively assessed. As a result of a side-by-side comparison with a conventional check-sheet manual billing system, it is apparent that the RIS reduces the errors inherent in manual systems. Subjectively, it is also apparent that personnel prefer the computerized system to the manual charge sheets.

Accounting↗

PubMed1990

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter.

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense x-rays up to 17.9 keV, although higher energies are easily attainable through the use of frequency doubling methods, alteration of the energy of the electron beam and coupling to conventional laser inputs.

Electrons↗

PubMed1986

Medical image management: practical, legal and ethical considerations.

The data acquired by the new medical imaging techniques, in many ways, exceeded our ability to properly store, transmit and use the images produced. As diagnostic imaging procedures become progressively less invasive and traumatic, they are being applied to a much larger patient population. The decrease in memory and other instrumentation costs, along with expanded technological capability of computer systems, has provided medicine an opportunity to create network systems for the storage, processing, recall, and remote location of these diagnostic images. Therefore, problems of access and confidentiality have become increasingly important. This communication will consider certain medical, legal, and ethical aspects of these technologies of data acquisition, storage, manipulation and retrieval.

Computers↗

PubMed1986

Medical image management.

Medical image management is becoming increasingly complex as additional data are produced by equipment using digital techniques. As the requirements to store and display these images increase, the following questions become important: (a) What methods can be used to ensure that information given to the physician represents the originally acquired data? (b) What technology and methods are needed to guarantee that information is presented in a timely fashion when requested? (c) How can an image archiving and transmission system be designed to protect the patient's rights of confidentiality? The authors discuss the legal implications of digital archiving of image information and propose some approaches to designing systems that provide the most information to the physician and yet attempt to minimize infringement of the patient's rights.

Communication↗

PubMed1978

Pilonidal cyst: an operative approach.

An operative technic is presented which has been used on fifty-four patients with pilonidal cyst. This technic has resulted in primary union and complete healing within six weeks in 89 per cent of cases. The use of an incision that crosses the vertical gluteal fold at an angle and eliminates the suture line in the gluteal fold has been beneficial in all patients on whom it was used.

Humans↗

PubMedDate not supplied

Digital image motion correction by spatial warp methods.

A technique for correction of motion between images which are obtained in high-speed digital subtraction or cine angiographic acquisitions is being tested. The method is based on the application of quadratic polynomial equations which transform one image so that it matches a reference image. Images which have been processed in this manner can be summed to improve the signal-to-noise ratios over individual images. The technique for motion correction currently being tested uses operator interaction to establish the appropriate polynomial transformation. An operator selects fiducial (reference) points on an image which will be the reference. Then he selects the corresponding fiducial points on the image to be processed. The algorithm calculates the coefficients of a pair of quadratic polynomial equations and applies them to each pixel in the image. Results demonstrate the application of the technique in phantoms and in digitized cine angiograms.

Angiography↗