A method for synthetic aperture tissue harmonic imaging is investigated. It combines synthetic aperture sequential beamforming (SASB) with tissue harmonic imaging (THI) to produce an increased and more uniform spatial resolution and improved side lobe reduction compared to conventional B-mode imaging. Synthetic aperture sequential beamforming tissue harmonic imaging (SASB-THI) was implemented on a commercially available BK 2202 Pro Focus UltraView ultrasound system and compared to dynamic receive focused tissue harmonic imaging (DRF-THI) in clinical scans. The scan sequence that was implemented on the UltraView system acquires both SASB-THI and DRF-THI simultaneously. Twenty-four simultaneously acquired video sequences of in-vivo abdominal SASB-THI and DRF-THI scans on 3 volunteers of 4 different sections of liver and kidney tissues were created. Videos of the in-vivo scans were presented in double blinded studies to two radiologists for image quality performance scoring. Limitations to the systems transmit stage prevented user defined transmit apodization to be applied. Field II simulations showed that side lobes in SASB could be improved by using Hanning transmit apodization. Results from the image quality study show, that in the current configuration on the UltraView system, where no transmit apodization was applied, SASB-THI and DRF-THI produced equally good images. It is expected that given the use of transmit apodization, SASB-THI could be further improved.

Objective: To explore the possible association between weight class and prevalence of caries among children born 2005-2007, living in Nuuk, Greenland, at time of school entry.Design: A cross-sectional register study based on data from electronic medical records(EMR) and oral health data from public health and dental care facilities.Methods: Data from routine examinations of children at time of primary school entry, including height and weight, were obtained from the EMRs. Dental charts recording oral health and caries were collected from public dental healthcare service. The prevalence of caries was calculated as the proportion of included children with dft score (decayed and/or filled non-permanent teeth) ≥1.Results: 55%(373/681) had relevant data recorded in EMRs and dental charts, and could be included in the study. The prevalence of dental caries was 57.1%(213/373). The prevalence of caries increased with higher weight class,but no statistically significant trend was observed(p=0.063).Conclusions: Increasing prevalence of caries with increasing weight class was observed in this study. A linear trend could not be confirmed statistically. The high prevalence of caries and overweight indicate the need for continued focus on preventative initiatives and monitoring. A combined strategy targeting both caries and overweight may be considered.

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.

This paper presents an imaging technique for synthetic aperture (SAI) tissue harmonic imaging (THI) on a commercial ultrasound system. Synthetic aperture sequential beamforming (SASB) is combined with a pulse inversion (PI) technique on a commercial BK 2202 UltraView system. An interleaved scan sequence that performs dynamic receive focused (DRF) imaging and SASB, both using PI, is implemented. From each acquisition four images can be created: DRF image, SASB image, tissue harmonic DRF image (DRF-THI), and tissue harmonic SASB image (SASB-THI). For SASB imaging, a fixed transmit and receive focus at 80 mm and an F# of 3 is applied. For DRF imaging, default scanner settings are used, which are a focus at 85 mm and F# of 5.7 in transmit and a dynamic receive aperture with an F# of 0.8. In all cases a 2.14 MHz one-and-ahalf cycle excitation transmit waveform is used. A BK 8820e 192 element convex array transducer is used to conduct scans of wire phantoms. The-6 dB and-20 dB lateral resolution is measured for each wire in the phantom. Results show that the-6 dB lateral resolution for SASB-THI is as good as for DRF-THI except at the point of the virtual source. SASB-THI even shows 7% reduction in-6 dB lateral resolution for the deepest wire at 100 mm. The-20 dB resolution for SASB-THI at [25, 50, 75, 100] mm was reduced by [5, 0-34, 11] % compared to DRF-THI, which shows, that except for the point of the virtual source, the lateral resolution was improved by SASB-THI. A successful implementation of SASB-THI was achieved on a commercial system, which can be used for future pre-clinical trials.