3D Printed Calibration Micro-phantoms for Validation of Super-Resolution Ultrasound Imaging

Ommen, Martin Lind; Schou, Mikkel; Beers, Christopher; Jensen, Jørgen Arendt; Larsen, Niels Bent; Thomsen, Erik Vilain

doi:10.1109/ultsym.2019.8926292

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…This was beamformed with a F-number of 0.7 and a Hanning apodization for both transmit and receive. Imaging was conducted on a 3-D printed point spread function (PSF) phantom [52] with scattering cavities in a 6 × 4 × 4 grid with a 2.05 mm spacing in all three directions. The scatterers are 205 µm wide along the x − y axes, but only 80 µm in the z direction.…”

Section: A B-mode Performance Of Row-column Arraysmentioning

confidence: 99%

Anatomic and Functional Imaging Using Row–Column Arrays

Jensen

Schou

Jorgensen

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Row-column (RC) arrays have the potential to yield full three-dimensional ultrasound imaging with a greatly reduced number of elements compared to fully populated arrays. They, however, have several challenges due to their special geometry. This review paper summarizes the current literature for RC imaging and demonstrate that full anatomic and functional imaging can attain a high quality using synthetic aperture (SA) sequences and modified delay-and-sum beamforming. Resolution can approach the diffraction limit with an isotropic resolution of half a wavelength with low side-lobe levels, and the field-ofview can be expanded by using convex or lensed RC probes. GPU beamforming allows for 3 orthogonal planes to be beamformed at 30 Hz, providing near real time imaging ideal for positioning the probe and improving the operator's workflow. Functional imaging is also attainable using transverse oscillation and dedicated SA sequence for tensor velocity imaging for revealing the full 3-D velocity vector as a function of spatial position and time for both blood velocity and tissue motion estimation. Using RC arrays with commercial contrast agents can reveal super resolution imaging with isotropic resolution below 20 µm. RC arrays can, thus, yield full 3-D imaging at high resolution, contrast, and volumetric rates for both anatomic and functional imaging with the same number of receive channels as current commercial 1-D arrays.

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Section: A B-mode Performance Of Row-column Arraysmentioning

confidence: 99%

Anatomic and Functional Imaging Using Row–Column Arrays

Jensen

Schou

Jorgensen

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

Self Cite

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“…The imaging capabilities of the probe was evaluated using the SARUS system by scanning a wire phantom, a cyst phantom, and a stereolithography 3D printed hydrogel phantom with isolated 205×205×80 µm 3 embedded cavities, which function as point scatter targets [76]. The scatterers were placed in a 6 × 4 × 4 grid with a spacing of 2.05 mm.…”

Section: Imagingmentioning

confidence: 99%

A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging

Grass

Engholm

Havreland

et al. 2022

IEEE Open J. Ultrason., Ferroelect., Freq. Contr.

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This paper presents the design, fabrication, and characterization of a 190+190 row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) array integrated in a custom hand-held probe handle. The array has a designed 4.5 MHz center frequency in immersion and a pitch of 95 µm which corresponds to ≈ λ/4. The array has a 2.14 × 2.14 cm 2 footprint including an integrated apodization scheme to reduce ghost echoes when performing ultrasound imaging. The array was fabricated using a combination of fusion and anodic bonding, and a deposit, remove, etch, multistep (DREM) etch to reduce substrate coupling and improve electrode conductivity. The transducer array was wire-bonded to a rigid-flex printed circuit board (PCB), encapsulated in room temperature vulcanizing (RTV) silicone polymer, electromagnetic interference (EMI) shielded, and mounted in a 3D-milled PPSU probe handle. The probe was characterized using the SARUS experimental scanner and 3D volumetric imaging was demonstrated on scatter and wire phantoms. The imaging depth was derived from tissue mimicking phantom measurements (0.5 dB MHz −1 cm −1 attenuation) by estimating the SNR at varying depths. For a synthetic aperture imaging sequence with 96+96 emissions the imaging depth was 3.6 cm. The center frequency measured from the impulse response spectra in transmit and pulse-echo was 6.0 ± 0.9 MHz and 5.3 ± 0.4 MHz, and the corresponding relative bandwidths were 62.8 ± 4.5 % and 86.2 ± 10.4 %. The fabrication process showed clear improvement in relative receive sensitivity and transmit pressure uniformity compared to earlier silicon-on-insulator (SOI) based designs. However, at the same time it presented yield problems resulting in only around 55 % elements with a good response.

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“…Imaging was conducted on a 3-D printed point spread function (PSF) phantom [23] with scattering cavities in a 6 × 4 × 4 grid with a 2.05 mm spacing in all three directions. The scatterers are 205 µm wide along the x − y axes, but only 80 µm in the z direction.…”

Section: Data Acquisition and Beamformingmentioning

confidence: 99%

Synthetic Aperture High Quality B-mode Imaging with a Row-Column Array Compared to Linear Array Imaging

Jensen

Schou

Ommen

et al. 2022

2022 IEEE International Ultrasonics Symposium (IUS)

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Row-column (RC) matrix probes can yield 3-D volumetric imaging using a number of receiving elements similar to traditional linear arrays for commercial scanners. Some doubts have, however, been raised on the B-mode image quality of RC probes. It is hypothesized that synthetic aperture (SA) RC imaging can yield a better volumetric resolution than commercial spatially translated linear arrays, and at the same time attain volume rates similar to frame rates for single slice linear array scanning. A Vermon 6 MHz 128 × 128 elements RC array with λ pitch was used on a Verasonics Vantage 256 scanner. A SA sequence with 2 × 96 emissions on the rows and columns and reception on all 128 orthogonal elements were employed giving a 62.5 Hz volume rate for a pulse repetition frequency of 12 kHz. The resolution and contrast were compared to an optimized SA sequence for a 256-elements GE L3-12D 6 MHz linear array probe, where the volume was acquired using a linear probe translation in the elevation direction. Imaging was conducted on a 3-D printed point spread function (PSF) phantom with scattering voids in a 6 × 4 × 4 grid with a 2.05 mm spacing in all three directions. The exposed kidney of a Sprague-Dawley rat was also scanned in vivo with the RC probe. B-mode images of the 3-D printed PSF phantom were shown with a 40 dB dynamic range along with the linear array scans. An isotropic resolution of (1.05λ , 1.10λ , 0.62λ ) = (x, y, z) was obtained for the row-column probe. The linear array probe had an elevation resolution determined by the geometric elevation focus of the array, and therefore the four rows of point scatterers could not be differentiated in the elevation direction due to the fixed elevation focus. The data rates were identical for the two arrays, but the RC array yielded an isotropic PSF with an improved contrast, and a 62.5 Hz volume rate comparable to normal linear array imaging. In vivo kidney images for the three orthogonal planes were shown with a 60 dB dynamic range demonstrating the isotropic speckle pattern in all three directions for all depths. The SA imaging RC sequence thus yielded a PSF independent of orientation and depth. Any slice plane in the volume therefore had a uniform speckle pattern, contrast, and resolution, demonstrating that RC arrays can yield higher quality B-mode images than linear arrays. The penetration depth of the probe and sequence was also measured to be 550λ corresponding to 141 mm.

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3D Printed Calibration Micro-phantoms for Validation of Super-Resolution Ultrasound Imaging

Cited by 5 publications

References 15 publications

Anatomic and Functional Imaging Using Row–Column Arrays

Anatomic and Functional Imaging Using Row–Column Arrays

A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging

Synthetic Aperture High Quality B-mode Imaging with a Row-Column Array Compared to Linear Array Imaging

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