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by
  • Benjamin C. Kreager 1,
  • Wei-Yi Chang 2 and
  • Xiaoning Jiang 1,*
  • et al.

Reviewer 1: Anonymous Reviewer 2: Anonymous Reviewer 3: Anonymous

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors
  1. The study uses static gelatin-cellulose phantoms with bovine blood, which lack physiological flow dynamics, tissue motion, and biological complexity. This limits the clinical relevance of the findings, as real surgical conditions involve pulsatile blood flow, tissue deformation, and heterogeneous acoustic properties. Include validation under dynamic conditions (e.g., flow phantoms with pulsatile pumps) or preliminary in vivo testing to demonstrate performance in biologically relevant environments. Address how factors like flow velocity and tissue motion might affect MFSR contrast.
  2. While the manuscript mentions limitations of external ultrasound and Doppler, it provides limited quantitative comparison with other minimally invasive imaging modalities in terms of resolution, contrast, or clinical practicality. Claims of superiority need stronger benchmarking. Add a comparative table contrasting ROSUS with existing technologies across key metrics: resolution, penetration depth, contrast mechanism, integration complexity, and real-time capability. Explicitly state advantages over side-looking OCT needles or photoacoustic approaches.
  3. The mechanical scanning protocol is slow, making real-time imaging impractical for clinical use. The manuscript mentions future work on faster acquisition but does not quantify current limitations or propose concrete solutions for real-time guidance. Provide data on current acquisition time per volume and discuss technical pathways to real-time operation. Include a feasibility analysis of integrating ROSUS into clinical workflow without procedural delays.
  4. The discussion briefly mentions limitations but does not critically address key issues: the impact of high-frequency attenuation in real tissues, potential fragility of the 45° transducer mounting under needle insertion forces, or electrical interference in clinical environments.
  5. The study lacks rigorous statistical analysis. CNR and area measurement errors are reported without standard deviations, confidence intervals, or sample size justification. The single-experiment approach limits assessment of reproducibility.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study addresses the complication of hemorrhage caused by accidental blood vessel puncture during biopsy procedures by developing a biopsy needle system integrated with Rotational Oblique Spectral Ultrasound (ROSUS) imaging. By utilizing a transducer mounted at a fixed angle, combined with synchronized rotational-axial scanning and Multifrequency Signal-Ratio (MFSR) processing technology, the system achieves simultaneous forward- and side-looking imaging capabilities. Phantom experiments validate the system's performance, demonstrating its effectiveness in distinguishing blood vessels from surrounding tissues and providing safer, more accurate guidance for biopsy procedures. Targeting critical clinical needs, this research features both innovation and practicality, holding significant academic value.

Recommendations：

  1. In Section 2.1, the filtering parameters for MFSR signals are presented without sufficient justification, merely based on empirical conclusions. It is recommended to supplement the rationale and selection criteria for these filtering parameters.
  2. The study claims that the ROSUS method overcomes the bottleneck of insufficient blood-tissue contrast compared to traditional B-mode imaging. However, it lacks an analysis of its limitations relative to other state-of-the-art techniques in the same field. Relevant discussions should be added to provide a comprehensive evaluation.
  3. Key experiments, such as resolution measurements and phantom imaging tests, do not include explicit descriptions of experimental repeatability (e.g., number of repetitions, statistical analysis of results). It is suggested to supplement this information to enhance the reliability and rigor of the findings.
  4. Format inconsistencies are present in the manuscript. For example, the unit of acoustic impedance in Table 1 is written as both "MRayl" and "Mrayl". It is recommended to review all formatting elements and correct such inconsistencies to ensure standardization.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors
  1. Explain clearly in the introduction section what is new compared to Doppler, IVUS, OCT, and photoacoustic needles rather than your combination. Furthermore, add some sentences about the layout of the paper at the end of the introduction section.
  2. Add one figure (or a block-diagram) to the section of materials and methods before the subsection, that shows (needle, transducer, signal, MFSR and finally 3D image) with some sentences showing the overall process in brief.
  3. Add a short paragraph in section 2.1 that explains MFSR in simple language not technical rather than the equation. 
  4. All the 3 equations are correct and there are no mathematical errors.
  5. Add a new short subsection between section 2 and section 3 (results), showing step by step how a doctor would use ROSUS in a real hospital. Please describe the steps of; before insertion, during insertion, vessel detection, taking the biopsy, after biopsy. In addition, explain how a radiologist or surgeon would actually use this in practice? This will make the paper more engineering-focused.
  6. Add statistical analysis to the results, showing (mean plus minus standard deviation) of CNR for each case. 
  7. Discuss how your system will work when the blood is flowing.
  8. Add a table to the results comparing your system (ROSUS) with Doppler and contrast-enhanced ultrasound.
  9. Add a limitation that this study is phantom and not yet used in patient, and explain how long it takes for one 3D scan (scanning time).
  10. Add more recent references (2024-2025) to the paper.
< !--a=1-->< !--a=1--> Comments on the Quality of English Language

There are many long sentences in the introduction and discussion, as well as there are minor grammatical errors, therefore one more language editing is required.

 

 

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Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors
  1. The current system requires approximately 50 minutes​ to acquire a full 3D volumetric dataset, which is clinically impractical for real-time biopsy guidance. While the authors note that continuous rotation could improve speed, the manuscript lacks a concrete technical roadmap or quantitative analysis of the hardware/software bottlenecks. A detailed discussion of achievable frame rates and engineering trade-offs would better contextualize the translational potential.
  2. Real tissues exhibit varying attenuation and scattering properties, which could affect the reliability of frequency-dependent backscatter ratios. The absence of perfused phantom or animal model testing leaves open questions about performance under clinical conditions.
  3. The oblique transducer is fixed with epoxy, but the manuscript does not evaluate mechanical durability under simulated insertion forces or cyclic fatigue. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have answered all my questions.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf