Motion-compensated noninvasive periodontal health monitoring using handheld and motor-based photoacoustic-ultrasound imaging systems

Simultaneous visualization of the teeth and periodontium is of significant clinical interest for image-based monitoring of periodontal health. We recently reported the application of a dual-modality photoacoustic-ultrasound (PA-US) imaging system for resolving periodontal anatomy and periodontal pocket depths in humans. This work utilized a linear array transducer attached to a stepper motor to generate 3D images via maximum intensity projection. This prior work also used a medical head immobilizer to reduce artifacts during volume rendering caused by motion from the subject (e.g., breathing, minor head movements). However, this solution does not completely eliminate motion artifacts while also complicating the imaging procedure and causing patient discomfort. To address this issue, we report the implementation of an image registration technique to correctly align B-mode PA-US images and generate artifact-free 2D cross-sections. Application of the deshaking technique to PA phantoms revealed 80% similarity to the ground truth when shaking was intentionally applied during stepper motor scans. Images from handheld sweeps could also be deshaken using an LED PA-US scanner. In ex vivo porcine mandibles, pigmentation of the enamel was well-estimated within 0.1 mm error. The pocket depth measured in a healthy human subject was also in good agreement with our prior study. This report demonstrates that a modality-independent registration technique can be applied to clinically relevant PA-US scans of the periodontium to reduce operator burden of skill and subject discomfort while showing pot

Brown adipose tissue does not seem to mediate metabolic adaptation to overfeeding in men

Objective: Brown adipose tissue (BAT) generates heat in response to cold, and low BAT activity has been linked to obesity. However, recent studies were inconclusive as to whether BAT is involved in diet-induced thermogenesis and mitigates weight gain from prolonged overeating. Therefore, this study investigated whether BAT activity is related to metabolic adaptation arising from 8 weeks of overfeeding in humans. Methods: Fourteen men (aged 24 ± 3 years, BMI 24.5 ± 1.6 kg/m2) were overfed by 40% for 8 weeks. Before and after, energy expenditure and metabolic adaptation were measured by whole-room respiratory calorimetry. A marker of BAT activity was measured using infrared imaging of the supraclavicular BAT depot. Results: At the end of 8 weeks of overfeeding, metabolic adaptation—defined as the percent increase in sleeping energy expenditure beyond that expected from weight gain—rose from −0.9 ± 3.9% to 4.7 ± 5.6% (P = 0.001). However, BAT thermal activity was unchanged (P = 0.81). Moreover, BAT thermal activity did not correlate with the degree of metabolic adaptation (P = 0.32) or with the change in body weight (P = 0.51). Conclusions: BAT thermal activity does not change in response to overfeeding, nor does it correlate with adaptive thermogenesis. Our data suggest that BAT does not mediate metabolic adaptation to overeating in humans

Regularized Capon Beamformer Using ℓ1-Norm Applied to Photoacoustic Imaging

Delay-and-Sum (DAS), as a non-adaptive beamforming method, is one of the most common algorithms used in Photoacoustic imaging due to its simple implementation. The results obtained from this algorithm suffer from low resolution and high sidelobes. The adaptive Minimum variance (MV) method improves the image quality compared to DAS in terms of resolution and contrast. In this paper, it is proposed to add a ℓ1-norm regularization term to the conventional MV minimization problem and create a new sparse beamforming method, named Modified-Sparse-Mv (ms-Mv)algorithm. In fact, the sparsity of the output is forced to the beampattern by adding this new sparse added term, which results in more noise reduction and sidelobe suppression compared to MV. The minimization problem is convex, and therefore, it can be solved using an iterative algorithm. The results show that the proposed MS-MV method improves the signal-to-noise-ratio for about 5.36 dB and 6.44 dB compared to DAS and MV, respectively, for the designed wire phantom.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Acoustical Wavefield Imagin