No abstract

A new method of three-dimensional (3-D) reconstruction of 2-D ultrasound images of the kidney is described. It is based on a coordinated spatial reconstruction of sequential cross-sectional images. The ultrasound head is moved longitudinally between two rails (parallel sections) and rotated. With a suitable computer program and contouring of each cross-section (so that the organ limits are defined for the computer) these cross-sectional pictures can be reconstructed into 3-D organ images. The kidney can then be presented spatially either as a binary picture or with closed surface. Ultrasound investigators are still unaccustomed to colour reproduction of 3-D reconstructed organs. It remains to be seen whether the method is valuable in routine clinical use.

This is a report on the clinical use of sonographic imaging. Experimental studies have shown that parallel sonographic sections are available only in vitro, which means no in-vivo three-dimensional reconstruction is possible as it is with magnetic resonance and computed tomography. The idea that a coordinated sequence of sections can be obtained by spatial rotation of the plane of sound so that the individual sections differ from one another by defined angular distances, enables three-dimensional reconstruction of sonographic in-vivo sections. A transducer was constructed that enables the production of sonographic sections rotating around a fixed center of rotation. Its clinical usefulness was tried and confirmed in the imaging of early pregnancies, benign and malignant carcinomas of the breast, and in imaging a gallbladder with a solitary gallstone. Three-dimensional imaging can be achieved either as a ring-shaped structure or with a continuous surface. This points to the possibility of diagnosing malformations early in pregnancy if the number of sections is sufficiently high. In tumour imaging the malignant tumour seems to be clearly distinguishable from the benign one; three-dimensional diagnosis is likely to furnish important additional criteria in diagnosis. Further clinical studies will have to verify this.

This is the first report in literature on three-dimensional imaging of organs via sonography. The relevant experiments were performed in vitro. Whereas MRI and CT can produce three-dimensional images of bodies by means of appropriate computer programmes, we had to search for special techniques in sonography that would communicate to the computer the exact positioning and arrangement of the individual segments to be reconstructed to supply a three-dimensional image. In MRI and CT the individual segments are arranged parallel to one another; the distance between the individual segments is known; all the computer has to do is to add up these segments to produce a spatial image. In contrast to this, conventional sonography cannot supply parallel segments or sections due to the unevenness of the human skin. Hence, it was not possible to use the computer programmes compiled for the three-dimensional reconstruction of MRI and CT images, in sonography; special transducer guides had to be constructed before this could be realised. One of our special constructions enabled parallel shifting of the transducer to obtain parallel segments or sections, and another construction enabled rotation of the transducer to obtain segments or sections differing from one another by a known angle of displacement. In this manner the computer was able to reconstruct an organ to supply a three-dimensional image--a first-time achievement. Using these devices, we examined a kidney in a water-bath. By means of outlining of the individual sonographic segments, only their surfaces are depicted, and these are reconstructed to produce a three-dimensional body by means of newly developed computer programmes.(ABSTRACT TRUNCATED AT 250 WORDS)

ZusammenfassungIn der vorliegenden Arbeit wird ein Verfahren vorgestellt, mit dem räumliche Ultraschallbildsequenzen aufgenommen und die Organschnitte zu einem 3D Körper rekonstruiert werden können. Für die folgende Auswertung wurden Tumore der weiblichen Brust aufgenommen, in ihrer texturellen Gewebecharakteristik gekennzeichnet und 3D rekonstruiert. Erste Ergebnisse zeigen, daß sich repräsentative Meßfenster normalen Brustgewebes, von Fenstern innnerhalb des Fibroadenoms und Carcinoms durch ihre textureile Gewebecharakteristik eindeutig diskriminieren lassen, so daß eine Klassifikation des Brustgewebes in Gewebeklassen eine Bildsegmentierung und 3D Rekonstruktion ermöglicht.