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Biomedical subjects

D J Valentino

Publications and source records attributed to D J Valentino.

9 recordsLinked to original sources
PubMed1999

Teleradiology in the operating room of the future.

Recent advances in magnetic resonance imaging (MRI) are rapidly making this modality the imaging method of choice for image-guided neurosurgical operations. However, to be ready for its prime time in the operating room (OR), utilization of MRI in the OR requires development of better techniques for image-guided navigation, as well as interactive real-time teleradiologic methods that will allow tele-collaboration between the surgeon and the radiologist. This presentation describes our work in progress toward achievement of teleradiology in the OR.

Computer Systems↗
PubMed1997

Assessment of intraaxial and extraaxial brain lesions with digitized computed tomographic images versus film: ROC analysis.

RATIONALE AND OBJECTIVES: The authors evaluated the diagnostic accuracy of viewing computed tomographic (CT) scans as film versus soft-copy images at a workstation. METHODS: Receiver operating characteristic analysis of the interpretation of 202 CT scans (103 were normal, 99 were abnormal) by five neuroradiologists was performed. Abnormal images contained high- or low-attenuation intraaxial lesions or extraaxial fluid (subdural, subarachnoid, or epidural hemorrhage). Hard copies were read on a standard light box, and digital images were examined at a 1,024 x 1,250 workstation. Lesion location and type and confidence ratings were recorded on a worksheet. RESULTS: There were no statistically significant differences in diagnostic accuracy between the two display modes. Reader performance was slightly better with the workstation in the assessment of low-attenuation lesions. CONCLUSION: Diagnostic accuracy is similar for CT scans displayed at a workstation and those displayed as hard copy in the assessment of subtle intra- and extraaxial brain lesions.

Brain↗
PubMed1996

Architectural design and tools to support the transparent access to hospital information systems, radiology information systems, and picture archiving and communication systems.

The fragmentation of the electronic patient record among hospital information systems (HIS), radiology information systems (RIS), and picture archiving and communication systems (PACS) makes the viewing of the complete medical patient record inconvenient. The purpose of this report is to describe the system architecture, development tools, and implementation issues related to providing transparent access to HIS, RIS, and PACS information. A client-mediator-server architecture was implemented to facilitate the gathering and visualization of electronic medical records from these independent heterogeneous information systems. The architecture features intelligent data access agents, run-time determination of data access strategies, and an active patient cache. The development and management of the agents were facilitated by data integration CASE (computer-assisted software engineering) tools. HIS, RIS, and PACS data access and translation agents were successfully developed. All pathology, radiology, medical, laboratory, admissions, and radiology reports for a patient are available for review from a single integrated workstation interface. A data caching system provides fast access to active patient data. New network architectures are evolving that support the integration of heterogeneous software subsystems. Commercial tools are available to assist in the integration procedure.

Computer Systems↗
PubMed1996

Ultrafast networks (ATM): first clinical experiences.

Ultrafast networks using asynchronous transfer mode (ATM) technology can provide the bandwidth and throughput that may be sufficient to satisfy the medical imaging community. Several trials are underway to assess the effect of ATM network capabilities on the clinical practice of radiology, by providing immediate interactive radiology consultations between subspecialists and general radiologists at affiliated academic institutions. The hardware to build such networks is now commercially available and its cost is decreasing steadily, but the monthly charges for ATM bandwidth use are still high. Nevertheless, given the tremendous increase in communication capability and data transfer rates possible with ATM networks, cost alone should not be the determining factor for selecting this technology. The ATM concept in general is first reviewed, followed by a description of early clinical ATM network installation in four medical environments worldwide. These medical clusters include: the UCLA affiliated hospitals (UCLA Medical Center, West LA VAMC and Olive-View UCLA Medical Center), the UCSF affiliated hospitals, Duke University Hospitals and a cluster of medical centers in Berlin which have all been connected via ATM networks. The use of ATM technology in these realistic clinical environments is discussed and evaluated for its potential impact on patient care and clinical teaching within radiology departments. From this preliminary study it is concluded that image communications over a regional PACS using an ATM network can allow interactive consultations between different subspecialist and general radiologists or other specialized radiologists spread over different medical centers.

Computer Systems↗
PubMed1996

The virtual aneurysm. Virtual reality in endovascular therapy.

Image guided therapies, such as new endovascular procedures for treating brain aneurysms are now in clinical use. To plan these procedures, physicians currently use angiography to view projectional images of anatomy and blood flow. There are currently no available tools for visualizing the details of complex blood flow or predicting the effects of specific treatments. To address this problem, we have created a virtual environment for the visualization of blood flow and the simulated effects of therapy in brain aneurysms. The "Virtual Aneurysm" is composed using a combination of image processing, flow simulation, scientific visualization, and virtual reality techniques.

Angiography, Digital Subtraction↗
PubMed1994

A nonlinear mathematical model for the development and rupture of intracranial saccular aneurysms.

Mathematical models of aneurysms are typically based on Laplace's law which defines a linear relation between the circumferential tension and the radius. However, since the aneurysm wall is viscoelastic, a nonlinear model was developed to characterize the development and rupture of intracranial spherical aneurysms within an arterial bifurcation and describes the aneurysm in terms of biophysical and geometric variables at static equilibrium. A comparison is made between mathematical models of a spherical aneurysm based on linear and nonlinear forms of Laplace's law. The first form is the standard Laplace's law which states that a linear relation exists between the circumferential tension, T, and the radius, R, of the aneurysm given by T = PR/2t where P is the systolic pressure. The second is a 'modified' Laplace's law which describes a nonlinear power relation between the tension and the radius defined by T = ARP/2At where A is the elastic modulus for collagen and t is the wall thickness. Differential expressions of these two relations were used to describe the critical radius or the radius prior to aneurysm rupture. Using the standard Laplace's law, the critical radius was derived to be Rc = 2Et/P where E is the elastic modulus of the aneurysm. The critical radius from the modified Laplace's law was R = [2Et/P]2At/P. Substituting typical values of E = 1.0 MPa, t = 40 microns, P = 150 mmHg, and A = 2.8 MPa, the critical radius is 4.0 mm using the standard Laplace's law and 4.8 mm for the modified Laplace's law.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, Ruptured↗
PubMed1994

A nonlinear mathematical model for the development and rupture of intracranial fusiform aneurysms.

Laplace's law, which describes a linear relation between the tension and the radius, is often used to characterize the mechanical response of the aneurysm wall to distending pressures. However, histopathological studies have confirmed that the wall of the fully developed aneurysm consists primarily of collagen and is subject to large increases in tension for small increases in the radius, i.e., a nonlinear relationship exists between the tension within the aneurysm wall and the radius. Thus, a nonlinear version of Laplace's law is proposed to accurately describe the development and rupture of a fusiform saccular aneurysm. The fusiform aneurysm was modelled as a thin-walled ellipsoidal shell with a major axis radius, Ra, minor axis radius, Rb, circumferential tension, S0, and meridional tension, S phi, with phi defining the angle from the surface normal. Using both linear and nonlinear models, differential expressions of the volume distensibility evaluated at 90 degrees were used to determine the critical radius of the aneurysm along the minor axis from S0 and S phi in terms of the following geometric and biophysical variables; A, elastic modulus of collagen; E, elastic modulus of the aneurysm (elastin and collagen); t, wall thickness; P, systolic pressure; and Ra. For typical physiological values of A = 2.8 MPa, E = 1.0 MPa, T = 40 microns, P = 150 mmHg, and Ra = 4Rb, the linear model yielded critical radii of 4.0 mm from S phi and 2.2 mm from S0. The resultant critical radius was 4.56 mm. Using the same values, the critical radii from the tension components of the nonlinear model were 3.5 mm from S phi and 1.9 mm from S0.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, Ruptured↗