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Introduction/Aims Quantitative muscle ultrasound offers biomarkers that aid in the diagnosis, detection, and follow‐up of neuromuscular disorders. At present, quantitative muscle ultrasound methods are 2D and are often operator and device dependent. The aim of this study was to combine an existing device independent method with an automated ultrasound machine and perform 3D quantitative muscle ultrasound, providing new normative data of healthy controls. Methods In total, 123 healthy volunteers were included. After physical examination, 3D ultrasound scans of the tibialis anterior muscle were acquired using an automated ultrasound scanner. Image postprocessing was performed to obtain calibrated echo intensity values based on a phantom reference. Results Tibialis anterior muscle volumes of 61.2 ± 24.1 mL and 53.7 ± 22.7 mL were scanned in males and females, respectively. Echo intensity correlated with gender**, age**, fat fraction*, histogram kurtosis**, skewness* and standard deviation** (*P < .05, **P < .01). Outcome measures did not differ significantly for different acquisition presets. The 3D quantitative muscle ultrasound revealed the non‐uniformity of echo intensity values over the length of the tibialis anterior muscle. Discussion Our method extended 2D measurements and confirmed previous findings. Our method and reported normative data of (potential) biomarkers can be used to study neuromuscular disorders.

Photoacoustic imaging (PAI) enables the visualization of optical contrast with ultrasonic imaging. It is a field of intense research, with great promise for clinical application. Understanding the principles of PAI is important for engineering research and image interpretation.Aim: In this tutorial review, we lay out the imaging physics, instrumentation requirements, standardization, and some practical examples for (junior) researchers, who have an interest in developing PAI systems and applications for clinical translation or applying PAI in clinical research.Approach: We discuss PAI principles and implementation in a shared context, emphasizing technical solutions that are amenable to broad clinical deployment, considering factors such as robustness, mobility, and cost in addition to image quality and quantification.Results: Photoacoustics, capitalizing on endogenous contrast or administered contrast agents that are approved for human use, yields highly informative images in clinical settings, which can support diagnosis and interventions in the future.Conclusion: PAI offers unique image contrast that has been demonstrated in a broad set of clinical scenarios. The transition of PAI from a "nice-to-have" to a "need-to-have" modality will require dedicated clinical studies that evaluate therapeutic decision-making based on PAI and consideration of the actual value for patients and clinicians, compared with the associated cost.

Adding volumetric ultrasound (3DUS) to MRI

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Fusion-based ultrasound (US)-guided biopsy in breast is challenging due to the high deformability of the tissue combined with the fact that the breast is usually differently deformed in CT, MR, and US acquisition which makes registration difficult. With this phantom study, we demonstrate the feasibility of a fusion-based ultrasound-guided method for breast biopsy. 3D US and 3D CT data were acquired using dedicated imaging setups of a breast phantom freely hanging in prone position with lesions. The 3D breast CT set up was provided by Koning (Koning Corp., West Henrietta, NY). For US imaging, a dedicated breast scanning set up was developed consisting of a cone-shaped revolving water tank with a 152-mmsized US transducer mounted in its wall and an aperture for needle insertion. With this setup, volumetric breast US data (0.5x0.5x0.5 mm 3 voxel size) can be collected and reconstructed within 2 minutes. The position of the lesion as detected with breast CT was localized in the US data by rigid registration. After lesion localization, the tank rotates the transducer until the lesion is in the US plane. Since the lesion was visible on ultrasound, the performance of the registration was validated. To facilitate guided biopsy, the lesion motion, induced by needle insertion, is estimated using cross-correlation-based speckle tracking and the tracked lesion visualized in the US image at an update frequency of 10 Hz. Thus, in conclusion a fusion-based ultrasound-guided method was introduced which enables ultrasound-guided biopsy in breast that is applicable also for ultrasound occult lesions.

Photoacoustic (PA) signals are typically broadband in nature. The bandwidth of PA signals depends on the size distribution of the underlying chromophores. Typically, conventional ultrasound (US) transducers, designed for pulse-echo imaging, have limited bandwidth, which reduces their sensitivity to the broadband PA signal. The rejection of out-of-band signals impairs image reconstruction, leading to the loss of image details. Visualization of biological structures, in particular deep targets with a range of sizes requires large acquisition bandwidth. In this work, we combine PA data acquired with two conventional US array probes with complementary frequency bands in order to widen the bandwidth. However, the two conventional transducers also differ in sensitivity and combining the data results in misrepresentation of PA signal strengths. Therefore, in this article we report a novel PA-based method to calibrate the relative sensitivities of the transducers. The proposed method was applied in various scenarios, including imaging vascular structures in vivo. Results revealed that it is feasible to visualize targets varying widely in sizes while combining complementary information acquired with dual US transducers. In addition, the application of sensitivity compensation ratios avoids misrepresentation in the imaging scheme by accounting for sensitivity differences of both transducers during image acquisition.

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