What primarily separates Minimal Residual Disease (MRD) from general residual disease?

The extreme sensitivity required for identification, implying microscopic persistence

The key differentiator between general residual disease and Minimal Residual Disease (MRD) lies in the quantity and the required level of detection sensitivity. General residual disease might describe a remaining focus of pathology that could potentially be visible or measurable using standard diagnostic approaches, perhaps a microscopic trace left after a surgeon excises a tumor nodule. In contrast, MRD refers to disease levels so minute—often microscopic—that they fall below the reliable threshold of standard clinical and imaging assessments. Identifying MRD necessitates highly sensitive, specialized molecular techniques capable of detecting persistence at levels where one malignant cell might exist among a million normal cells.