ARTMA (Advanced Real Time Motion Analysis)

Announced at Den Haag 1991


In several areas of medicine, such as orthopaedics and rehabilitation, but also maxillofacial and plastic surgery, it is often important for the physician to acquire exact information on the location and movements of bones and other parts of the human body. For example, in the case of a knee injury it is important for the physician to find out whether it consists of a lesion of the cross ligaments. Because of muscular compensation, such a lesion can go unnoticed. But by recording knee movements over a long time, the physician can determine the nature of the lesion - and treat it properly.

Most systems for the study of motion now available to the physician rely on mechanical recording devices or on post processing of stereophotometric data of various imaging systems. To get a complete picture, the physician has to analyze separately images from different imaging devices, including video recordings, x-ray images, computed tomography (CT) and magnetic-resonance imaging (MRI). None of the current systems are capable of displaying motion in real time, and require computer processing after completion of the recording of data.

EUREKA Project EU 662, ARTMA, developed by Artma Medizintechnik GmbH in Vienna, is taking motion analysis a step further. By integrating various imaging systems with information from sensors attached to the body, the project will equip hospitals around Europe with better diagnostic abilities.

Exact coordinates in three dimensions

"Our approach is completely different to current methods," explains Dr. Michael Truppe from Artma Medizintechnik. "We do use video images - but only for visualization, not for data acquisition. We get 3-dimensional data from a network of sensors attached to the body parts we are interested in, and then combine this with other types of images and video recordings using specially developed software. Because no post processing is required, we have the first and only real-time display of motion."

The sensors are either used to pinpoint certain points on the body to record their location, or can be attached to a part of the body to study motion in detail. Usually four sensors are connected to the computer, and work by recording changes in magnetic reference fields caused by motion. However several other methods for creating 3D data are available. One of them, a sonic digitizer, uses three or more microphones to locate the position of tiny "sparkers" that emit sound. As the body moves, the sensors supply data on their position to a three-dimensional digitizer, which converts the signals into data usable by the computer program. This software calculates, in real time, the coordinates of the sensors in relationship to a reference point, which can be attached to the body.

This data is then integrated with images obtained by photography, x-ray radiography and, in some cases, CT scans. The images are scanned and stored in the computer, or are retrieved from the computerised data-storage systems used in the hospital. By combining 3D data with existing video recordings or scanned images, the physician can avoid subjecting the patient to prolonged x-rays and tests.

The location of the sensors are then superimposed on a video recording. Alternatively, the computer can display a stick figure in which the position of the actual bone structure is displayed rather than the position of the sensors. By updating the coordinates sixty times per second, ARTMA allows the study of motion in real time. For example, by attaching sensors to the shoulder, elbow, wrist and palm of a patient with an arm injury, and recording the motions of the arm, such as wrist flexions and rotations, at regular intervals, a physician can monitor progress in such a patient undergoing physiotherapy.

Better Diagnosis Through Synergy

Because of the high level of accuracy of the coordinates supplied by the 3D digitizer, the system allows a more precise study of motion and diagnosis. "In itself this is a new type of information available to the physician, with new diagnostic value," says Dr. Truppe. An important aspect of the system is that it operates on a second level by enhancing existing information. One type of information gives us a certain amount of diagnostic help. When there are several different types of information available, then their combination can supply new diagnostic information, not available from any of the information types singly."

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© Copyright 1996 Artma. All rights reserved. Last modified May 6, 1996.