The ACR Medical Image Quality Assessment System (MIQAS): A Unified Approach to Image Quality Assessment in Radiology

Image quality is central to the accurate interpretation of medical imaging, yet it remains inconsistently defined and assessed across clinical practice. To address this, the ACR has developed the Medical Image Quality Assessment System (MIQAS), a standardized, descriptive framework that characterizes image quality based on its alignment with relevant clinical task requirements. This framework will serve as the image quality assessment standard for all relevant ACR programs, including the ACR Accreditation Program, the Reporting and Data Systems programs, Practice Parameters and Technical Standards, and the ACR Learning Network. In this framework, image quality is defined as the degree to which an image approximates an exact representation of its subject in ways that matter for a specific clinical task. Image quality assessments may be quantitative, semiquantitative, or categorical, but should be reproducible and valid. Under this framework, key image quality elements of an imaging examination are individually scored and aggregated into a composite score on a 5-point scale: 0 (out of standard), 1 (nondiagnostic), 2 (limited), 3 (adequate), and 4 (excellent). For "bounded" image quality factors that involve trade-offs with cost or risk-such as radiation dose in CT-the goal is "adequate" image quality. For unbounded factors without such trade-offs-such as positioning or labeling-the goal is "excellent" image quality. Individual scoring systems will be developed under this overarching framework for specific modalities, organ systems, and diagnostic tasks. Once published, each scoring system becomes an ACR-supported standard, updated periodically based on emerging evidence. In this way, the MIQAS framework is designed to unify image quality assessment across ACR programs, guide local quality improvement efforts, and serve as a unified image quality assessment standard for research, education, and technology development.