Academy of Diagnostic & Osteopathic Medicine
The Journal of
Diagnostic Medicine
The Journal of Diagnostic Medicine is an open-access research journal dedicated to advancing diagnostic thinking in medicine. The journal publishes original research, observational analyses, and interdisciplinary scholarship focused on early disease detection, diagnostic innovation, medical imaging, and the biological and systemic processes that precede clinical pathology.
The journal is focused on diagnosis, emphasizing how disease is identified, interpreted, and understood, particularly through imaging-based observation, systems biology, and real-world diagnostic patterns. Contributions may include exploratory research, hypothesis-generating frameworks, and integrative models that examine environmental, metabolic, and structural contributors to disease development.
The Journal of Diagnostic Medicine serves as a platform for practical, real-life diagnostic research that expands clinical insight, supports preventive approaches, and encourages rigorous inquiry into emerging diagnostic concepts, while remaining distinct from established clinical practice guidelines.
Disclaimer
Content published in The Journal of Diagnostic Medicine is intended for educational and research purposes only. It does not constitute medical advice, diagnosis, or clinical guidance and should not be used to make individual health decisions.
Articles may present observational findings, diagnostic frameworks, and emerging hypotheses that are not part of established clinical standards or consensus guidelines. These contributions are intended to expand diagnostic understanding and scientific inquiry, not to replace current standards of care or inform direct clinical decision-making.
Clinical decisions should always be made in consultation with a licensed healthcare professional. The views expressed in published content are those of the authors and do not necessarily reflect the views of the journal or its affiliates.
Nussbaumer, K. (2025). Validation of the Breast Ultrasound Lesion Location (B.U.L.L.): A Structured Anatomical System to Improve Reproducibility Over Clock-Based Localization. Journal of Diagnostic Medicine, 1(1), e008.
Validation of the Breast Ultrasound Lesion Locator (B.U.L.L.): A Structured Anatomical System to Improve Reproducibility Over Clock-Based Localization
From the Author
The Breast Ultrasound Lesion Locator (B.U.L.L.) was developed in response to repeated clinical and educational observations that lesion localization in breast ultrasound can be difficult to reproduce reliably across examinations. In practice, lesions identified on an initial study are not always confidently re-identified on follow-up, contributing to diagnostic uncertainty, additional imaging, procedural delays, and patient discomfort.
B.U.L.L. was designed as a non-diagnostic, anatomy-based localization framework intended to improve reproducibility without altering interpretive criteria or existing reporting standards. The system emphasizes fixed anatomical landmarks, bounded regions, and depth-based organization to support consistent lesion re-localization across operators and care settings.
Recognizing the importance of compatibility with established clinical workflows, B.U.L.L. was intentionally designed to function alongside traditional clock-face localization rather than replace it. This parallel approach allows clinicians to retain familiar descriptive language while benefiting from a structured anatomical reference that may reduce ambiguity and improve continuity of care.
The intent of this work is to contribute to ongoing efforts to improve reproducibility in diagnostic imaging and to encourage further investigation into standardized, anatomy-based localization systems that prioritize clinical accuracy, usability, and patient experience.
Validation of the Breast Ultrasound Lesion Locator (B.U.L.L.): A Structured Anatomical System to Improve Reproducibility Over Clock-Based Localization
Background:
Accurate and reproducible lesion localization is essential in breast ultrasound for follow-up imaging, image-guided procedures, and surgical planning. The conventional clock-face method relies on imaginary reference lines and variable distance measurements that are sensitive to operator technique, patient positioning, and tissue mobility, which can limit reproducibility across examinations.
Purpose:
To describe and validate the Breast Ultrasound Lesion Locator (B.U.L.L.), a structured, anatomy-based localization system designed to improve reproducibility while functioning alongside traditional clock-face localization.
Methods:
B.U.L.L. defines the nipple and areola as fixed central anatomical landmarks, divides the breast into three concentric depth rings (R1–R3), and segments the breast surface into twelve numbered segments. Lesion location is recorded using a combined segment and depth descriptor, defining a bounded anatomical area rather than a single radial line. Optional system components include optical projection to scale across breast sizes, photographic documentation with non-diagnostic lesion markers, and an ultrasound-scannable stabilization device (Echo Band). A Phase 2 comparative validation study evaluated lesion localization using B.U.L.L. versus clock-based methods, assessing interobserver agreement, repeatability, localization time, and user confidence.
Results:
B.U.L.L. demonstrated improved localization agreement and repeatability compared with clock-face localization. Use of bounded anatomical segments reduced ambiguity for lesions located between traditional clock positions, while depth-ring organization supported consistent re-identification of posterior and small lesions. Users reported improved efficiency and confidence during follow-up and procedural applications.
Conclusion:
The Breast Ultrasound Lesion Locator (B.U.L.L.) is a non-diagnostic, anatomy-based localization system that improves reproducibility of lesion localization in breast ultrasound. Designed for immediate implementation as an adjunct to existing workflows, B.U.L.L. enhances localization clarity without replacing established reporting standards.
Keywords:
Breast ultrasound; lesion localization; reproducibility; anatomical segmentation; diagnostic imaging; clock-face method
Full Manuscript
2. Introduction
Accurate lesion localization is a critical component of breast ultrasound imaging, influencing follow-up examinations, image-guided procedures, surgical planning, and longitudinal research. When a lesion is identified, the ability to reliably re-localize that finding on subsequent examinations is essential for distinguishing true interval change from technical or positional variation. Inconsistent localization can introduce diagnostic uncertainty, contribute to additional imaging or procedures, and increase patient discomfort and healthcare utilization.
In routine clinical practice, lesion location in breast ultrasound is most commonly documented using the clock-face method. This approach conceptualizes the breast as a clock dial when viewed face-on and describes findings by clock position (e.g., “2 o’clock”), often combined with distance from the nipple and quadrant descriptors. The clock-face method is intuitive, widely adopted, and compliant with existing reporting standards, providing a familiar framework for communicating laterality and approximate lesion location.
Despite its widespread use, clock-face localization has notable limitations. The method relies on imaginary reference lines and free-text descriptions that are sensitive to probe orientation, patient positioning, tissue compression, and operator technique. As a result, lesion location may be described differently across examinations or observers. Lesions near the nipple, for example, may be labeled as “12 o’clock” or “6 o’clock” depending on probe orientation, underscoring the inherent ambiguity of the system. In addition, depth information is not inherently encoded and is often inconsistently documented, even when distance from the nipple is recorded. These factors may complicate reliable lesion re-identification on follow-up imaging or during image-guided interventions.
To address these challenges, structured anatomical localization approaches have been introduced in breast imaging. Techniques such as extended field-of-view ultrasound with nipple-to-lesion distance measurement, transducer-tracking platforms, and interactive breast mapping software have demonstrated improved reproducibility by anchoring lesion location to fixed anatomical reference points. These approaches reflect a broader trend in medical imaging toward standardized, anatomically grounded localization frameworks designed to reduce subjectivity and improve consistency across examinations, operators, and care settings.
The Breast Ultrasound Lesion Locator (B.U.L.L.) was developed within this context as a simplified, anatomy-based localization framework designed to improve reproducibility while remaining compatible with routine clinical workflows. B.U.L.L. defines the nipple and areola as central anatomical landmarks, divides the breast into bounded surface segments, and incorporates depth-based organization to describe lesion location as a reproducible anatomical area rather than a single radial line. The anatomical structure, segmentation, and depth-ring organization of the B.U.L.L. system are illustrated in Figure 1.
Figure 2 presents example applications of the B.U.L.L. framework, demonstrating how lesion locations are recorded using simple segment and depth descriptors across multiple findings. These examples illustrate the practical simplicity of the system when applied in clinical and educational settings.
Importantly, B.U.L.L. is intentionally non-diagnostic and was designed to function alongside traditional clock-face localization rather than replace it. This parallel approach allows clinicians to retain familiar descriptive language while benefiting from a structured anatomical reference that may improve localization consistency and confidence.
The purpose of this study is to describe the design and structure of the Breast Ultrasound Lesion Locator and to present Phase 2 validation of its reproducibility, usability, and clinical applicability compared with traditional clock-based localization.
Figure 1. Schematic representation of the Breast Ultrasound Lesion Locator (B.U.L.L.). The system defines the nipple (N) and areola (A) as central anatomical landmarks, divides the breast into three concentric depth rings (R1–R3), and segments the breast surface into twelve numbered regions. Lesion location is documented using a combined regional and depth descriptor to define a bounded anatomical area rather than a single radial line.
Figure 2. Example application of B.U.L.L., illustrating straightforward documentation of lesion locations using segment and ring identifiers Larger Circle R3-1, Medium Circle R2-2, Smaller Circle R1-8).
Figure 3. BULL breast segmentation diagram. The circular map shows 12 clock positions and three concentric rings surrounding the nipple and areola. Clicking a segment highlights the region and reports its identifier.
Lesion location is documented as a combined regional and depth descriptor (e.g., “Ring 2, Segment 7 = R2-7”), thereby describing a bounded anatomical area rather than a single imaginary radial line. This structure reduces ambiguity for lesions located between traditional clock positions and provides consistent depth encoding across examinations.
B.U.L.L. further incorporates optional tools intended to support practical implementation across a range of breast sizes and clinical contexts. An optical projection–based approach allows the region-and-ring framework to be scaled to individual anatomy without altering the underlying relationships between segments and depth rings. Photographic documentation with non-diagnostic circular lesion markers provides a persistent visual reference for follow-up imaging and procedural planning. In addition, an optional ultrasound-scannable stabilization device (the Echo Band) is designed to reduce tissue mobility and gravitational shift, particularly in medium to larger breasts, while preserving ultrasound visibility and supporting patient comfort.
Importantly, B.U.L.L. is intentionally non-diagnostic and does not alter interpretive criteria or replace established reporting standards. It was designed to function alongside traditional clock-face localization as an adjunct that enhances localization clarity while respecting existing workflows and professional judgment.
The purpose of this study is to describe the design and structure of the Breast Ultrasound Lesion Locator and to present Phase 2 validation of its reproducibility and usability compared with traditional clock-based localization.
3. Methods
System Design and Anatomical Framework
The Breast Ultrasound Lesion Locator (B.U.L.L.) is a structured anatomical localization system designed for breast ultrasound imaging. The system defines the nipple (N) and areola (A) as fixed central anatomical landmarks and divides the breast into three concentric depth rings: R1 (inner breast), R2 (mid-breast), and R3 (posterior breast, closest to the chest wall). The breast surface is further divided into twelve numbered segments, which function as location identifiers rather than clock positions.
Lesions are localized using a combination of segment number and depth ring. This approach describes lesion location as a bounded anatomical area rather than a single imaginary radial line.
Optical Projection and Scaling
B.U.L.L. incorporates an optical projection–based approach to scale the localization framework across varying breast sizes. The projected reference functions similarly to a flashlight or projector. When positioned closer to the breast surface, the projected image corresponds to smaller breast volumes. As the projection source is moved farther away, the image expands proportionally to accommodate larger breast sizes.
This method allows a single standardized locator to be used across a range of breast sizes without altering the underlying anatomical relationships between segments and depth rings.
Image Capture and Lesion Marking
Once the projected image is aligned with the breast anatomy, the image may be captured photographically. When a lesion is identified on ultrasound, its corresponding location is marked on the captured image. A circular outline is placed over the lesion location to indicate relative size and to confirm segment and depth ring assignment.
These markers are non-diagnostic and are used solely to support localization and repeatability.
Echo Band Stabilization
To further improve reproducibility and patient comfort, the system incorporates an ultrasound-scannable breast stabilization device known as the Echo Band. The Echo Band is a flexible band approximately four inches in width, designed primarily for use in patients with medium to larger breast sizes.
When applied circumferentially, the Echo Band gently stabilizes breast tissue without compressing or distorting anatomy. Because the material is fully scannable, ultrasound imaging can be performed directly through the band without artifact. When patient weight does not vary significantly between examinations, breast position relative to the chest wall remains highly reproducible.
The Echo Band also covers the nipple during examination, which may reduce feelings of exposure and improve patient comfort, particularly during prolonged imaging or procedures.
Procedural Applications
The Echo Band may also be used during image-guided procedures such as biopsies. Stabilization of breast tissue helps reduce gravitational movement and tissue displacement, supporting precise targeting and needle placement without interfering with ultrasound visualization.
4. Results
Initial application of the B.U.L.L. system demonstrated feasibility, usability, and improved reproducibility in educational and pilot research settings. Users were able to consistently identify and re-identify lesion locations using combined segment and depth ring descriptors. Use of bounded anatomical segments reduced ambiguity associated with clock-face boundaries, particularly for lesions located between traditional clock positions.
Photographic documentation with non-diagnostic circular lesion markers supported clear confirmation of lesion location and facilitated repeat localization. Use of the Echo Band improved consistency of breast positioning and enhanced confidence during follow-up imaging and procedural planning.
Localization Reproducibility
Use of the B.U.L.L. system resulted in more consistent lesion localization compared with traditional clock-face descriptions. Localization using combined segment and depth ring identifiers allowed users to re-identify lesion locations with greater confidence across repeat examinations.
Bounded anatomical segments reduced ambiguity for lesions located between traditional clock positions, while depth ring assignment supported consistent localization of posterior and small lesions that are often challenging to reproduce using clock-based descriptors alone.
Interobserver and Intraobserver Agreement
Users demonstrated improved agreement when documenting lesion location with B.U.L.L. compared with clock-face localization. The structured segment-and-ring framework reduced variability in location description between users and across repeated examinations by the same user.
Workflow Efficiency and Usability
Application of B.U.L.L. did not disrupt standard scanning workflows. Users reported efficient localization and ease of use, particularly during follow-up examinations where prior lesion location documentation was available. Photographic documentation supported rapid confirmation of lesion location and reduced uncertainty during repeat imaging.
Effect of Stabilization on Localization
Use of the Echo Band was associated with improved consistency of breast positioning, particularly in patients with medium to larger breast sizes. Reduced tissue mobility facilitated repeat localization and improved user confidence during both diagnostic imaging and procedural applications.
User Confidence
Users reported greater confidence in lesion re-localization when using B.U.L.L. compared with clock-face descriptors alone, particularly in cases involving multiple lesions or subtle findings.
Discussion
Accurate and reproducible lesion localization is fundamental to breast ultrasound, influencing follow-up imaging, image-guided procedures, surgical planning, and longitudinal research. The traditional clock-face method remains widely used because it is intuitive and compatible with existing reporting standards. However, clock-based localization relies on imaginary reference lines and free-text descriptions that are sensitive to probe orientation, patient positioning, tissue mobility, and operator technique. As a result, lesion localization using the clock method may vary between observers and across examinations, particularly for retroareolar, posterior, small, or subtle lesions.
The findings of this study demonstrate that the Breast Ultrasound Lesion Locator (B.U.L.L.) addresses these limitations by providing a structured, anatomy-based localization framework. By defining fixed anatomical landmarks, dividing the breast into bounded surface segments, and incorporating depth-based organization, B.U.L.L. reduces ambiguity inherent in clock-face descriptions and supports more consistent lesion re-localization across examinations and operators.
Structured anatomical localization has shown similar benefits in other breast imaging contexts and across imaging specialties. Extended field-of-view ultrasound techniques that document nipple-to-lesion distance, digital breast mapping platforms that track transducer position, and interactive reporting templates have all demonstrated improved interobserver agreement and localization consistency compared with free-text clock-based descriptions. These approaches share a common goal: replacing subjective localization with reproducible, anatomically grounded mapping. B.U.L.L. aligns with this broader trend while remaining low-cost, non-diagnostic, and compatible with routine clinical workflows.
Depth-based organization represents a particular advantage of the B.U.L.L. system. While clock-face localization may include distance measurements, depth information is often inconsistently recorded or omitted. Assignment of lesions to concentric depth rings provides a consistent framework for encoding anterior, mid-breast, and posterior lesion location, supporting reliable re-identification during follow-up and procedural planning.
Optional system components further enhance reproducibility. Photographic documentation with non-diagnostic circular lesion markers provides a persistent visual reference that facilitates repeat localization and reduces uncertainty during follow-up imaging. Use of the Echo Band improves consistency of breast positioning by reducing tissue mobility, particularly in patients with medium to larger breast sizes, and enhances user confidence during both diagnostic and interventional applications.
Importantly, B.U.L.L. was designed to function as an adjunct, not a replacement, to clock-face localization. Parallel use allows clinicians to retain familiar descriptive language while benefiting from a structured anatomical reference. This approach supports incremental adoption and minimizes disruption to established workflows, a key consideration for clinical implementation.
This study has limitations. Validation was conducted in educational and pilot research settings, and outcomes were primarily qualitative. Larger, multi-center studies with quantitative measures of interobserver agreement, time-to-localization, and procedural outcomes are needed to further evaluate the system’s clinical impact and comparative performance relative to other structured localization technologies.
Despite these limitations, the results support the potential of B.U.L.L. as a practical and effective tool for improving reproducibility in breast ultrasound localization. By emphasizing anatomical structure, bounded segmentation, and depth-based organization, B.U.L.L. reflects a broader movement toward standardized anatomical mapping that has improved accuracy and communication in other imaging disciplines.
Conclusion
The Breast Ultrasound Lesion Locator (B.U.L.L.) is a novel, anatomy-based localization framework designed to improve reproducibility and consistency in breast ultrasound imaging. By emphasizing fixed anatomical landmarks, bounded surface segments, and depth-based organization, the system addresses limitations inherent in traditional clock-based localization.
B.U.L.L. is non-diagnostic and can be implemented immediately as an adjunct without disrupting existing clinical workflows or reporting standards. Its design allows parallel use with traditional clock descriptors, supporting incremental adoption while enhancing confidence in lesion re-localization, procedural planning, and follow-up.
Integration of optical projection, photographic documentation, and optional stabilization through the Echo Band further strengthens the system’s ability to maintain consistent breast positioning across imaging sessions while improving patient comfort. As adoption expands, B.U.L.L. provides a structured foundation for improving localization consistency across breast imaging, image-guided procedures, and research applications.