Characterization of the Ultrasound Localization Microscopy Resolution Limit in the Presence of Image Degradation

McCall, Jacob R.; Dayton, Paul A.; Pinton, Gianmarco

doi:10.1109/tuffc.2021.3112074

Cited by 7 publications

(8 citation statements)

References 59 publications

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“…Finally, because we used a clinical ultrasound scanner with a low frame rate, a high prazosin dose was used to ensure a measurable response in the intrarenal vessels, especially the medullary microcirculation with a slow flow. For detection of subtler velocity alterations, optimization of SRUS acquisition or post-processing parameters such as increased frame rate or improved tracking algorithms that can cope with overlapping MBs are necessary [61], especially since transcutaneous scanning needed for longitudinal studies will introduce additional challenges for MB tracking [62].…”

Section: Discussionmentioning

confidence: 99%

Super-Resolution Ultrasound Imaging Can Quantify Alterations in Microbubble Velocities in the Renal Vasculature of Rats

et al. 2022

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Super-resolution ultrasound imaging, based on the localization and tracking of single intravascular microbubbles, makes it possible to map vessels below 100 µm. Microbubble velocities can be estimated as a surrogate for blood velocity, but their clinical potential is unclear. We investigated if a decrease in microbubble velocity in the arterial and venous beds of the renal cortex, outer medulla, and inner medulla was detectable after intravenous administration of the α1-adrenoceptor antagonist prazosin. The left kidneys of seven rats were scanned with super-resolution ultrasound for 10 min before, during, and after prazosin administration using a bk5000 ultrasound scanner and hockey-stick probe. The super-resolution images were manually segmented, separating cortex, outer medulla, and inner medulla. Microbubble tracks from arteries/arterioles were separated from vein/venule tracks using the arterial blood flow direction. The mean microbubble velocities from each scan were compared. This showed a significant prazosin-induced velocity decrease only in the cortical arteries/arterioles (from 1.59 ± 0.38 to 1.14 ± 0.31 to 1.18 ± 0.33 mm/s, p = 0.013) and outer medulla descending vasa recta (from 0.70 ± 0.05 to 0.66 ± 0.04 to 0.69 ± 0.06 mm/s, p = 0.026). Conclusively, super-resolution ultrasound imaging makes it possible to detect and differentiate microbubble velocity responses to prazosin simultaneously in the renal cortical and medullary vascular beds.

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Section: Discussionmentioning

confidence: 99%

Super-Resolution Ultrasound Imaging Can Quantify Alterations in Microbubble Velocities in the Renal Vasculature of Rats

et al. 2022

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“…The behavior of NDs (extravasation) and resulting MBs (persistence, flow) within the tumor microenvironment and its impact on the localization precision of ULM and P-ULM should be investigated. ND confinement in vessels might affect the amplitude and shape of the vaporization signals [54], while the attenuation and speed of sound variations introduced by different tissue compositions might impact the localization performances of both techniques [55]. Lastly, this study was conducted above physiological temperature, at 50°C.…”

Section: Phantommentioning

confidence: 99%

Passive Ultrasound Localization Microscopy of Nanodroplet Vaporizations During Proton Irradiation

Heymans

Collado-Lara

Rovituso³

et al. 2022

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

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Superheated nanodroplets (NDs) were recently proposed for in vivo proton range verification, owing to their ability to vaporize into echogenic microbubbles (MBs) upon exposure to ionizing radiation. In a previous publication, vaporization events were detected with 2D Ultrasound Localization Microscopy (ULM) based on a pulse-echo method. Here, we introduce P-ULM, a passive version of ULM, based on the detection of acoustic signatures emitted by vaporizing NDs, without actively transmitting ultrasound. Due to the lack of a time reference for the trigger of the ND vaporization, the time differences of arrival to each transducer element are used to retrieve the position of vaporizing NDs. P-ULM, compared to ULM, can continuously detect and super-localize sparse radiation-induced vaporization events with inherent specificity against already existing microbubbles, which otherwise would hinder range verification in the presence of vascular flow. We evaluated the localization performances of both methods theoretically and experimentally, by interleaving active and passive acquisitions on ND-phantoms irradiated with protons. P-ULM offered a higher sensitivity to vaporizations, as it detected twice as many events as ULM. Both methods retrieved, in the acoustic lateral direction, the proton range and range dispersion with sub-millimeter accuracy. In the acoustic axial direction, despite a degraded theoretical resolution limit, P-ULM retrieved the proton spot size with an accuracy similar to ULM. Importantly, P-ULM detected vaporization events with high specificity in the presence of flowing MBs, which makes the technique a candidate for in vivo proton range verification in the presence of flow.

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“…The primary strength of this probe lies in its ability to reconstruct volumetric images over a large region without the requirement of extra hardware. This, however, does come at the cost of image resolution, which will only be further degraded from the phase aberration and reverberation clutter introduced by imaging through the skull [33]. As far as we are aware, there have been no demonstrations of the use of this probe for human transcranial applications to-date.…”

Section: Introductionmentioning

confidence: 99%

“…There are also significant sources of degradation, such as reverberation and phase aberration, when imaging through the skull. McCall et al demonstrated that the these sources of image degradation could impact the resolution in ULM up to 150 µm [33]. Therefore, to achieve high-quality ultrasonic human transcranial imaging, it is important to design a transducer capable of high-SNR acquisition to overcome the reverberation clutter, for example.…”

Section: Introductionmentioning

confidence: 99%

The development of a 1.25 MHz 1024-channel sparse array for human transcranial imaging: in vitro characterization

McCall,

Jones,

Santibanez

et al. 2023

Meas. Sci. Technol.

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Ultrasound imaging is overwhelmingly used as 2D modality even though 3D imaging capabilities have existed for decades. Recent generational shifts toward super-resolution ultrasound imaging and functional ultrasound imaging, especially in the brain, have generated renewed and sustained interest in acquiring truly volumetric, 4D data. However, volumetric imaging approaches are currently limited to small animals, due in part to the difficulty of imaging transcranially in humans and due to a lack of imaging arrays designed for this purpose. Clinical translation of these recent techniques as well as conventional diagnostic B-mode imaging may thus benefit from array designs that capitalize on large channel count imaging systems. We have designed and developed a 1024-channel sparse array with a 65 mm circular aperture and a 1–2 MHz bandwidth. This unique transducer achieves an aperture that is far larger than conventional matrix probes using a sparse arrangement of elements ordered in a density-tapered spiral design. This design has significantly decreased grating lobes compared to a matrix array probe. The large aperture of this probe also enables acquisition over a large field of view with a significant depth of more than 100 mm. Simulations, acoustic characterization, and in vitro tests demonstrate that this transducer achieves a high focal gain that enables ultrasonic visualization beneath the human skull and at large depths due to its low F-number capabilities. Furthermore, we show that this transducer is capable of high point target contrast and high soft tissue contrast, with contrast-to-noise ratios up to 1.9 when imaging transcranially through a 3 mm thick section of human skull. Because of the large surface area of this probe, it can capture over 3 coherence lengths in each dimension and is, therefore, able to able to ‘average out’ the aberration over a large surface area. This transducer is poised to have a significant clinical impact in transcranial human imaging.

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Characterization of the Ultrasound Localization Microscopy Resolution Limit in the Presence of Image Degradation

Cited by 7 publications

References 59 publications

Super-Resolution Ultrasound Imaging Can Quantify Alterations in Microbubble Velocities in the Renal Vasculature of Rats

Super-Resolution Ultrasound Imaging Can Quantify Alterations in Microbubble Velocities in the Renal Vasculature of Rats

Passive Ultrasound Localization Microscopy of Nanodroplet Vaporizations During Proton Irradiation

The development of a 1.25 MHz 1024-channel sparse array for human transcranial imaging: in vitro characterization

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