An ultrasonic imaging speckle-suppression and contrast-enhancement technique by means of frequency compounding and coded excitation

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 56; no. 7; pp. 1327 - 1339
• Main Authors: Sanchez, J., Oelze, M.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-07-2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic signal processing; Acoustics; Algorithms; Bandwidth; Biological and medical sciences; Compounding; Computer Simulation; Exact sciences and technology; Frequency measurement; Fundamental areas of phenomenology (including applications); Image coding; Image contrast; Image Processing, Computer-Assisted - methods; Image resolution; Imaging; Impulse response; Investigative techniques, diagnostic techniques (general aspects); Lesions; Medical sciences; Miscellaneous. Technology; Noise; Phantoms, Imaging; Physics; Pulse compression methods; Reproducibility of Results; Signal to noise ratio; Simulation; Speckle; Transducers; Ultrasonic imaging; Ultrasonic investigative techniques; Ultrasonography - methods; B scan; Acoustic interferometry; Ultrasound imaging; Detectability; Speckle; Experimental study; Pulse compression; Pulse code modulation; Modeling; Image quality; Pulse response; Medical imagery; Model test; Lesion; Acoustic image; Frequency mixing; Image contrast; Signal to noise ratio
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2009.1189

A method for improving the contrast resolution of B-mode images is proposed by combining the speckle-reduction technique of frequency compounding (FC) and the coded-excitation and pulse-compression technique called resolution enhancement compression (REC). FC suppresses speckle but at the expense of a reduction in axial resolution. Using REC, the axial resolution and bandwidth of the imaging system was doubled. Therefore, by combining REC with FC (REC-FC), the tradeoff between axial resolution and contrast enhancement was extended significantly. Simulations and experimental measurements were conducted with a single-element transducer (f/2.66) having a center frequency of 2.25 MHz and a -3-dB bandwidth of 50%. Simulations and measurements of hyperechoic (+6 dB) tissue-mimicking targets were imaged. Four FC cases were evaluated: full-, half-, third-, and fourth-width of the true impulse response bandwidth. The image quality metrics used to compare REC-FC to conventional pulsing (CP) and CP-FC were contrast-to-noise ratio (CNR), speckle signal-to- noise ratio, histogram pixel intensity, and lesion signal-to-noise ratio. Increases in CNR of 121%, 231%, 302%, and 391% were obtained in experiments when comparing REC-FC for the full-, half-, third-, and fourth-width cases to CP. Furthermore, smaller increases in CNR of 112%, 233%, and 309% were obtained in experiments when comparing CP-FC for the half-, third-, and fourth-width cases to CP. Improved lesion detectability was observed by using REC-FC.