System for analyzing high-resolution three-dimensional coronary angiograms.

Three-dimensional (3-D) high-resolution coronary angiograms offer a means for visualizing the entire coronary arterial tree from any orientation and for detecting and quantitating coronary arterial stenoses. Previously, a skilled operator had to perform several hours of tedious manual analysis using an interactive graphical user-interface (GUI) system (Tree Trace) to analyze a 3-D angiogram. The authors have devised an improved GUI system, consisting of three tools for analyzing 3-D angiograms. The Artery Extractor first performs automatic image-analysis operations to extract the central axes of the arterial tree. Next, using the Artery Display tool and results from the Artery Extractor, the operator can visualize structures in the angiogram and compute various measurements. Finally, the aforementioned Tree Trace tool can be used to manually correct irregularities in the automatically generated results of the Artery Extractor. The system greatly reduces operator analysis time, gives exactly reproducible results, uses true 3-D image-processing operations, and provides a comprehensive interface for visualizing and quantifying features of the 3-D coronary arteries.

Shape-based interpolation of tree-like structures in three-dimensional images.

Many three-dimensional (3-D) medical images have lower resolution in the z direction than in the x or y directions. Before extracting and displaying objects in such images, an interpolated 3-D gray-scale image is usually generated via a technique such as linear interpolation to fill in the missing slices. Unfortunately, when objects are extracted and displayed from the interpolated image, they often exhibit a blocky and generally unsatisfactory appearance, a problem that is particularly acute for thin treelike structures such as the coronary arteries. Two methods for shape-based interpolation that offer an improvement to linear interpolation are presented. In shape-based interpolation, the object of interest is first segmented (extracted) from the initial 3-D image to produce a low-z-resolution binary-valued image, and the segmented image is interpolated to produce a high-resolution binary-valued 3-D image. The first method incorporates geometrical constraints and takes as input a segmented version of the original 3-D image. The second method builds on the first in that it also uses the original gray-scale image as a second input. Tests with 3-D images of the coronary arterial tree demonstrate the efficacy of the methods.

Extraction of left-ventricular chamber from 3-D CT images of the heart.

A semiautomatic method is described for extracting the volume and shape of the left ventricular (LV) chamber from a dynamic spatial reconstructor cardiac volume. For a given volume, the operator first performs some simple manual edits. Then, an automated stage, which incorporates concepts from 3-D mathematical morphology and technology, the maximum-homogeneity filter, and an adaptive 3-D thresholder, extracts the LV chamber. The method gives more consistent measurements and demands considerably less operator time than manual slice-editing.

Regional wall thickening dynamics as an index of regional myocardial function

Angiogramas roentgen biplanares de ventrículos esquerdos caninos, isolados e mantidos funcionando metabolicamente, foram analisados em termos da taxa de aumento de espessura da parede durante a fase sistólica do ciclo cardíaco. A pressäo de enchimento de átrio esquerdo, a resistência à saída de fluxo na aorta, a frequência cardíaca e o fluxo coronariano foram controlados independentemente. Valores para o pico da taxa de aumento de espessura da parede, normalizado para valores instantâneos de espessuras de paredes, foram similares para paredes livres nas partes anterior e lateral de todos os ventrículos sob condiçöes hemodinâmicas similares. A taxa de aumento de espessura de parede variou linearmente e com a frequência cardíaca de estado permanante e fluxo arterial de coronária. Pouca mudança ocorreu na taxa de aumento da expessura da parede para uma faixa considerável de pressöes de enchimento mas houve uma consistente, porém pequena, diminuiçäo nesta taxa para valores elevados da resistência ao fluxo de saída da aorta. Os resultados levam a concluir que a taxa de aumento da espessura da parede ventricular é um bom indicador do estado inotrópico e/ou perfusäo regional do miocárdio