In-vivo evaluation of convex array synthetic aperture imaging

Pedersen, Morten Høgholm; Gammelmark, Kim; Jensen, Jørgen Arendt

doi:10.1016/j.ultrasmedbio.2006.07.041

Cited by 36 publications

(34 citation statements)

References 9 publications

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“…The HRI is dynamically focused in both transmit and receive yielding an improvement in resolution [6]. This has been confirmed with side-by-side comparisons with conventional ultrasound imaging in pre-clinical trials by Pedersen et al [7]. This imaging technique sets high demands on processing capabilities, data transport, and storage and makes implementation of a full SA system very challenging and costly.…”

Section: Introductionmentioning

confidence: 73%

Sequential beamforming for synthetic aperture imaging

2013

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a b s t r a c tSynthetic aperture sequential beamforming (SASB) is a novel technique which allows to implement synthetic aperture beamforming on a system with a restricted complexity, and without storing RF-data. The objective is to improve lateral resolution and obtain a more depth independent resolution compared to conventional ultrasound imaging. SASB is a two-stage procedure using two separate beamformers. The initial step is to construct and store a set of B-mode image lines using a single focal point in both transmit and receive. The focal points are considered virtual sources and virtual receivers making up a virtual array. The second stage applies the focused image lines from the first stage as input data, and take advantage of the virtual array in the delay and sum beamforming. The size of the virtual array is dynamically expanded and the image is dynamically focused in both transmit and receive and a range independent lateral resolution is obtained. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The lateral resolution increases with a decreasing F#. Grating lobes appear if F# 6 2 for a linear array with k-pitch. The performance of SASB with the virtual source at 20 mm and F# = 1.5 is compared with conventional dynamic receive focusing (DRF). The axial resolution is the same for the two methods. For the lateral resolution there is improvement in FWHM of at least a factor of 2 and the improvement at À40 dB is at least a factor of 3. With SASB the resolution is almost constant throughout the range. For DRF the FWHM increases almost linearly with range and the resolution at À40 dB is fluctuating with range. The theoretical potential improvement in SNR of SASB over DRF has been estimated. An improvement is attained at the entire range, and at a depth of 80 mm the improvement is 8 dB.

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Section: Introductionmentioning

confidence: 73%

Sequential beamforming for synthetic aperture imaging

2013

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“…A disadvantage of synthetic aperture imaging systems is tissue motion artifacts, although these artifacts have been found to have a minor impact on image quality (Jensen et al 2006;Pedersen et al 2007). Requesting patients to hold their breath and lie still most likely reduced these artifacts.…”

Section: Discussionmentioning

confidence: 99%

Clinical Evaluation of Synthetic Aperture Harmonic Imaging for Scanning Focal Malignant Liver Lesions

Brandt

Hemmsen

Hansen

et al. 2015

Ultrasound in Medicine & Biology

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Abstract-The purpose of the study was to perform a clinical comparison of synthetic aperture sequential beamforming tissue harmonic imaging (SASB-THI) sequences with a conventional imaging technique, dynamic receive focusing with THI (DRF-THI). Both techniques used pulse inversion and were recorded interleaved using a commercial ultrasound system (UltraView 800, BK Medical, Herlev, Denmark). Thirty-one patients with malignant focal liver lesions (confirmed by biopsy or computed tomography/magnetic resonance) were scanned. Detection of malignant focal liver lesions and preference of image quality were evaluated blinded off-line by eight radiologists. In total, 2,032 evaluations of 127 image sequences were completed. The sensitivity (77% SASB-THI, 76% DRF-THI, p 5 0.54) and specificity (71% SASB-THI, 72% DRF-THI, p 5 0.67) of detection of liver lesions and the evaluation of image quality (p 5 0.63) did not differ between SASB-THI and DRF-THI. This study indicates the ability of SASB-THI in a true clinical setting.

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“…Based on earlier publications of studies of clinical evaluation between pairs of sequences 6 and recommended testing procedurs according to recommendation 500 from ITU-R 7 for subjective quality assessment, we propose a methodology for the assessment of subjective image quality and penetration depth of medical ultrasound imaging.…”

Section: Discussionmentioning

confidence: 99%

Ultrasound image quality assessment: a framework for evaluation of clinical image quality

Hemmsen

Petersen

Nikolov³

et al. 2010

SPIE Proceedings

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Improvement of ultrasound images should be guided by their diagnostic value. Evaluation of clinical image quality is generally performed subjectively, because objective criteria have not yet been fully developed and accepted for the evaluation of clinical image quality. Based on recommendation 500 from the International Telecommunication Union -Radiocommunication (ITU-R) for such subjective quality assessment, this work presents equipment and a methodology for clinical image quality evaluation for guiding the development of new and improved imaging. The system is based on a BK-Medical 2202 ProFocus scanner equipped with a UA2227 research interface, connected to a PC through X64-CL Express camera link. Data acquisition features subject data recording, loading/saving of exact scanner settings (for later experiment reproducibility), free access to all system parameters for beamformation and is applicable for clinical use. The free access to all system parameters enables the ability to capture standardized images as found in the clinic and experimental data from new processing or beamformation methods. The length of the data sequences is only restricted by the memory of the external PC. Data may be captured interleaved, switching between multiple setups, to maintain identical transducer, scanner, region of interest and recording time on both the experimental-and standardized images. Data storage is approximately 15.1 seconds pr. 3 sec sequence including complete scanner settings and patient information, which is fast enough to get sufficient number of scans under realistic operating conditions, so that statistical evaluation is valid and reliable.

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In-vivo evaluation of convex array synthetic aperture imaging

Cited by 36 publications

References 9 publications

Sequential beamforming for synthetic aperture imaging

Sequential beamforming for synthetic aperture imaging

Clinical Evaluation of Synthetic Aperture Harmonic Imaging for Scanning Focal Malignant Liver Lesions

Ultrasound image quality assessment: a framework for evaluation of clinical image quality

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