Method of identifying tissue with intravascular ultrasound

摘要

The method involves replacing a metal guide wire with an acoustically transparent wire (1), pref. of thermoplastic material, to prevent artefacts in the ultrasonic signal. The transparent guide wire is given one or more x-ray proof markers without affecting the acoustic sensor (3). The tissue's mechanical properties are determined from its acoustic properties by subjecting scattered or reflected ultrasonic signals to special signal analysis in a conventional IVUS catheter system. The transducer stimulation is specified for increased penetration depth wrt. frequency, pulse duration and pulse power. The transmission pulse is also fine structure modulated to improve signal-to-noise ratio and superimposed with a frequency spectrum suitable for signal analysis. The backscatter signal is digitised without prior demodulation using a sufficiently high sampling frequency. The time and spectral parameters are associated with each backscatter pulse origin with high accuracy using a frequency analysis method with high time resolution.