THE SENSITIVITY OF NEW COLOR SYSTEMS IN BLOOD-FLOW DIAGNOSIS - THE MAXIMUM-ENTROPY METHOD AND ANGIO-COLOR-COMPARATIVE IN-VITRO FLOW MEASUREMENTS TO DETERMINE SENSITIVITY

Background: Two new blood-flow-diagnosis techniques have recently been developed as supplements to the established color techniques: the MEM (maximum entropy method) technique and color flow amplitude (power Do ppler). These are capable of representing blood flow in distinctly mor e slowly flowing areas than is possible with the conventional Doppler technique. Methods: Both methods make use of the Doppler technique in part, yet analyze the reflected signal in a different manner, in so do ing optimizing the relation between the noise and the signal. Measurem ents were obtained on two anatomic flow models to test the sensitivity of both techniques under slow flow conditions. Results: The slowest f low the MEM technique was capable of recording was 0.5 mm/s, whereas t he angiotechnique was able to detect 0.4 mm/s, albeit utilizing a 5-MH z transducer for the MEM technique and a 10-MHz transducer for the ang io technique. One may thus assume that the MEM technique would be stil l more sensitive when utilizing a 10-MHz transducer. The advantage of the MEM technique is its real-time flow representation: The angio tech nique requires a few seconds of acquisition time. This could have seri ous consequences during clinical utilization. Doppler sonography was m erely capable of detecting a minimum flow velocity of 15 mm/s. The ang io technique is less dependent on the angle during flow representation than the MEM technique. Conclusions: The distinctly higher sensitivit y of these two new color techniques offers new possibilities in the cl inical sector as far as the perfusion diagnosis of organs and tumors i s concerned.