Graphical 3D medical image registration and quantification.

We present a graphical three-dimensional method that facilitates image registration and fusion, and provides quantitative geometric and volume information. In particular it enhances the use of functional (radiopharmaceutical) imaging (SPECT, PET) which, though a powerful clinical tool, has the disadvantage of low spatial resolution and ill-defined boundaries. Registration between functional images and structural images (MRI, CT) can augment the anatomical context of these functional images.

Comparison of the prognostic utility of VEPs and SEPs in comatose children.

Visual evoked potentials and somatosensory evoked potentials were recorded in 37 children in coma soon after admission and then repeatedly during coma and emergence from coma. Evoked potentials were graded in 4 categories, ranging from normal to absent, and then related to patient outcome. Somatosensory evoked potentials were reliable predictors of outcome, particularly if both the initial and early repeated somatosensory evoked potentials were considered. Visual evoked potentials were not as reliable predictors as somatosensory evoked potentials; however, the presence or absence of both was significantly related to outcome. These data are generally consistent with the adult literature. We suggest that somatosensory evoked potentials be the evoked potential of choice in evaluating the prognosis of comatose children.

Three-dimensional data visualization and biomedical applications.

Three-dimensional data visualization is an important tool in several medical, scientific, and engineering areas. Visualization methods are based on a primitive representational element: contour, surface, or volume. Methods often incorporate options to cut open, see around, or see through structures, and form images in multiple windows or with animation. To visualize and interpret two or three related 3D data sets, composite imaging methods are required. The appropriate method depends on the user needs, application area, and available hardware. Visualization of 3D medical data is described for cranium/face, musculoskeletal systems, spine, intracranial structures, cardiovascular system, and radiation therapy.

A new noninvasive method for the simultaneous determination of cardiac output, VA/QC disparity, and the magnitude of peripheral perfusion, suitable for use in the critically ill patient.

A noninvasive technique for determining cardiac output, lung blood-tissue volume, and the volume of perfused body tissue in shock states has been developed from analysis of the pulmonary washout of several physiologically inert tracer gases. Canine preparations and a computer-based simulation were used to evaluate the accuracy and feasibility of the technique. The dogs were ventilated with 10% helium, 10% N2O, 0.45% C2H2, 39.5% N2, and 40% O2 mixture, and washed out with 60% N2 and 40% O2. End-tidal volume excretion differences between the three inert gases helium, N2O, and C2H2 resulted from differences in the blood/gas partition constants (lambda) of the test gases. Helium, which has a very low lambda, is contained in lung air space, whereas N2O and C2H2, with moderate lambda's, are distributed to lung air space, blood, and perfused tissues. Computer modeling of the cardiopulmonary and body perfusion gas transport permitted calculation of alveolar ventilation, VA/VA disparity, pulmonary blood-tissue volume, pulmonary blood flow, VAQc, and perfused body volume in the canine experiments. In experimental shock settings and in a variety of control situations over an eightfold range of flows the pulmonary blood flow calculated from the N2O and C2H2 washout was generally within +/- 15% of the cardiac output determined by the cardiogreen technique.

Early and long-term effects on direct myocardial revascularization on cardiac function: a prospective study using multivariable physiological analysis.

Perioperative and late follow-up hemodynamic cardiovascular studies to assess the effects of direct myocardial revascularization on cardiac function objectively have been completed on 51 patients. Analysis of the data delineated three distinct groups basedon the patterns of their early postoperative recovery. Group I patients (12) had a hyperdynamic cardiovascular response to operation and returned to a normal physiological range of cardiac function within 24 hours. Group II patients (24) initially had moderate to severe myocardial decompensation postoperatively but responded to inotropic support and moved into the normal physiological range within 24 to 48 hours. Group III patients (15) had severe, prolonged myocardial decompensation with little response to inotropic support. There were no early deaths in Group I, 1 early iatrogenic death in Group II, and 2 deaths from sepsis, 1 in Group I and 1 in Group II. All 7 cardiogenic deaths occurred in Group III patients. Late follow-up studies 4 to 23 months postoperatively have been completed on 29 patients. These showed cardiovascular stability in the mean values in Groups I and II. Significant improvement in mean cardiac function was seen in surviving Group III patients.

Estimation of blood gas contents from expired air under normal and pathologic conditions.

Methods of estimating arterial-venous O2 content difference, mixed venous CO2 content and tension, and average arterial CO2 content are presented. They are based on the continuous gas analysis of expired air during a prolonged expiration. The influence of CO2 storage in lung tissue and certain pathophysiologic conditions on the accuracy of these methods was systematically investigated with a comprehensive multi-chamber computer simulation of the lung. For normal levels of CO2 storage capacity, satisfactory estimates of arterial-venous O2 content difference are feasible for differences less than 8 volumes percent; with high levels of CO2 storage capacity, large errors can occur. Storage of CO2 in lung tissue causes large errors in the estimates of mixed venous CO2 content and tension, and average arterial CO2 content; reliable estimates do not appear to be feasible from analysis of expired gas. Simulated pathophysiologic conditions of interstitial pulmonary edema or atelectasis also introduce large errors. This analysis delineates the theoretic limitations of an estimation technique in clinical applications where acute respiratory dysfunctions occur.