title: Intravascular ultrasound tissue harmonic imaging in vivo.
abstract: Tissue harmonic imaging (THI) has been shown to increase image quality of medical ultrasound in the frequency range from 2 to 10 MHz and might, therefore, also be used to improve image quality in intravascular ultrasound (IVUS). In this study we constructed a prototype IVUS system that could operate in both fundamental frequency and second harmonic imaging modes. This system uses a conventional, continuously rotating, single-element IVUS catheter and was operated in fundamental 20 MHz, fundamental 40 MHz, and harmonic 40 MHz modes (transmit 20 MHz, receive 40 MHz). Hydrophone beam characterization measurements demonstrated the build-up of a second harmonic signal as a function of increasing pressure. Imaging experiments were conducted in both a tissue-mimicking phantom and in an atherosclerotic animal model in vivo. Acquisitions of fundamental 20 and 40 MHz and second harmonic acquisitions resulted in cross sections of the phantom and a rabbit aorta. The harmonic results of the imaging experiments showed the feasibility of intravascular THI with a conventional IVUS catheter both in a phantom and in vivo. The harmonic acquisitions also showed the potential of THI to reduce image artifacts compared to fundamental imaging.
authors.affiliation: Biomedical Engineering, Erasmus MC, University Medical Center, Rotterdam, The Netherlands. m.frijlink@erasmusmc.nl
authors.forename: Martijn E
authors.initials: ME
authors.lastname: Frijlink
authors.forename: David E
authors.initials: DE
authors.lastname: Goertz
authors.forename: Luc C A
authors.initials: LC
authors.lastname: van Damme
authors.forename: Rob
authors.initials: R
authors.lastname: Krams
authors.forename: Antonius F W
authors.initials: AF
authors.lastname: van der Steen
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000000981:diagnostic imaging*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018084:Ultrasonography, Interventional / Q000295:instrumentation* / Q000379:methods