Beyond single cut-off values in ultrasound: limitations and implications for context-aware radiology reporting.

Quantitative ultrasound frequently relies on single cut-off values to dichotomize continuous measurements into "normal" and "abnormal." Although embedded in workflows and guidelines, their biological plausibility and their external validity may be limited in heterogeneous clinical populations and across different technical settings. This review evaluates the conceptual foundations, clinical implications, and relevance of single cut-off values for contemporary radiology reporting. A critical review of studies, consensus statements, and international guidelines published between 1991 and February 2026 was conducted, predominantly via PubMed/MEDLINE, with emphasis on recent and clinically relevant evidence. Research on diagnostic accuracy, population-based studies, and methodological investigations was qualitatively synthesized to assess the biological, technical, and clinical limitations of fixed cut-off values in ultrasound. As this article was not designed as a systematic review, no formal meta-analysis or PRISMA flowchart was included. Most quantitative ultrasound parameters reflect continuous biological processes influenced by patient characteristics, technical factors, and operator variability. Dichotomization may lead to information loss, misclassification, and reduced generalizability, particularly near decision boundaries ("gray zones"). Evidence from vascular ultrasound, elastography, and organ volumetry supports continuous risk gradients rather than discrete biological thresholds. Reliance on single cut-off values in ultrasound largely reflects historical and methodological convention rather than biological discontinuities. Context-aware interpretation strategies, including percentile-based references, multivariable risk models, probabilistic reporting, and longitudinal assessment, may better reflect biological variability and diagnostic uncertainty. Thresholds may therefore evolve from rigid decision boundaries toward context-sensitive reference points within modern reporting frameworks, thereby helping radiologists communicate diagnostic uncertainty more transparently. CRITICAL RELEVANCE: This review critically assesses fixed ultrasound cut-offs and supports context-aware reporting to reduce misclassification near decision boundaries and improve individualized, clinically meaningful radiology interpretation. KEY POINTS: Single cut-off values remain widely used in quantitative ultrasound, despite uncertainty about their biological validity, diagnostic reliability, and generalizability in clinical practice. Fixed ultrasound thresholds remain clinically useful but may lead to misclassification when biological variability, technical factors, and clinical context are not accounted for.