Wideband harmonic imaging: A novel contrast ultrasound imaging technique

Abstract

A novel ultrasonic imaging method, wideband harmonic imaging, for nonlinear imaging of microbubble contrast agents is evaluated. In wideband harmonic mode, two pulses of alternate phase are send out. The image is then processed from the sum of both pulses, resulting in an image of nonlinear scatterers such as microbubbles. A prototype ultrasound system, Siemens Elegra, was evaluated with in vitro investigations and animal trials, using conventional, harmonic and wideband harmonic settings with the galactose based ultrasound contrast agent Levovist. Wideband harmonic imaging offers superior sensitivity for ultrasound contrast agents compared to conventional imaging and harmonic imaging. At low transmit power settings (MI 0. 1-0.5) the nonlinear response is already sufficient to generate a image of the blood pool distribution of Levovist in the rabbit kidney including the microvasculature, with clear delineation of vessels and perfused parenchyma. At high transmit amplitudes, nonlinear tissue response reduced the apparent image contrast between contrast agent and tissue. The results suggest that wideband harmonic imaging is currently the most sensitive contrast imaging technique, maintaining highest spatial resolution. This may add to image quality and offer new clinical potential for the use of ultrasound contrast agents such as Levovist.

Detection of Cardiac Right-to-Left Shunts by Contrast-Enhanced Harmonic Carotid Duplex Sonography

“…We made use of pulse inversion-based contrast-enhanced harmonic imaging, which enables the visualization of single UCA microbubbles in the vessel lumen because of their nonlinear backscatter. 16,17 Pulse inversion imaging differs from conventional second-harmonic imaging techniques, which use long pulses and filter the second-harmonic signal, because it transmits and receives 2 broadband ultrasound pulses, with the second being inverted. This results in near complete cancellation of the fundamental frequency and, because tissue emits few second harmonics, provides greater contrast of the microbubbles and higher spatial resolution.…”

“…The technique of extracranial sonography (ECS) using harmonic frequencies enables the visualization of even single UCA microbubbles because of their oscillation by the ultrasound beam. 16,17 This novel technique recently showed the ability to improve the detection of RLS in transthoracic and transesophageal echocardiography.…”

Management of hepatocellular carcinoma: The role of contrast-enhanced ultrasound

“…Among these new techniques, contrast enhanced ultrasound (CEUS) plays increasingly important roles in the management of HCC [2,[5][6][7][8] . Since the advent of the second generation microbubble contrast agents (such as SonoVue, Definity and Luminity) and nonlinear harmonic contrast imaging technique, CEUS has been applied to HCC management for more than ten years, including HCC surveillance, diagnosis, CEUS-guided treatment, treatment response evaluation and follow-up [9] . A series of CEUS application modes, such as 2D or 3D transabdominal CEUS and intraoperative CEUS (IO-CEUS), are developed and applied clinically for management of HCC [8] .…”

Liver-specific imaging with SHU 563A: Diagnostic potential of a new class of ultrasound contrast media

“…The signals originating form microbubbles due to stimulated acoustic emission can be used for specific detection of the ultrasound contrast agent with different techniques: conventional color Doppler and more complex pulse sequences such as wideband harmonic [5,6] in new high-end ultrasound equipment.…”