High frequency harmonic imaging in presence of intravascular stents

High frequency second harmonic imaging was compared with fundamental imaging when highly reflective stents were present in the near field of a spherically focused PVDF transducer. Hydrophone measurements of the harmonic beam at 40 MHz showed a relative lower signal strength in the near field compared to the fundamental modes at 20 and 40 MHz. The beam width (-3dB) of the fundamental 40 MHz and the harmonic 40 MHz, measured in the focal plane were both 80 microns. It was found that harmonic 40 MHz imaging mode suppressed reverberations from the stent by up to 14 dB compared to fundamental 20 MHz imaging.